| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Qu Wenruo | 6709 | 32.78% | 119 | 18.77% |
| Chris Mason | 3819 | 18.66% | 85 | 13.41% |
| Filipe David Borba Manana | 2517 | 12.30% | 35 | 5.52% |
| Christoph Hellwig | 1800 | 8.80% | 67 | 10.57% |
| Josef Bacik | 1476 | 7.21% | 39 | 6.15% |
| Josef Whiter | 757 | 3.70% | 45 | 7.10% |
| Miao Xie | 542 | 2.65% | 10 | 1.58% |
| David Sterba | 525 | 2.57% | 53 | 8.36% |
| Omar Sandoval | 309 | 1.51% | 9 | 1.42% |
| Liu Bo | 265 | 1.29% | 19 | 3.00% |
| Naohiro Aota | 211 | 1.03% | 17 | 2.68% |
| Jan Schmidt | 204 | 1.00% | 3 | 0.47% |
| Nikolay Borisov | 136 | 0.66% | 30 | 4.73% |
| Matthew Wilcox | 126 | 0.62% | 13 | 2.05% |
| Sweet Tea Dorminy | 114 | 0.56% | 3 | 0.47% |
| Yehuda Sadeh Weinraub | 107 | 0.52% | 1 | 0.16% |
| Johannes Thumshirn | 98 | 0.48% | 6 | 0.95% |
| Gerhard Heift | 76 | 0.37% | 1 | 0.16% |
| Jeff Mahoney | 65 | 0.32% | 7 | 1.10% |
| Vishal Moola (Oracle) | 62 | 0.30% | 2 | 0.32% |
| Sergei Trofimovich | 43 | 0.21% | 1 | 0.16% |
| Ethan Lien | 39 | 0.19% | 2 | 0.32% |
| Zheng Yan | 38 | 0.19% | 6 | 0.95% |
| Frank Holton | 36 | 0.18% | 1 | 0.16% |
| Linus Torvalds | 34 | 0.17% | 3 | 0.47% |
| Eric Sandeen | 28 | 0.14% | 3 | 0.47% |
| Chandra Seetharaman | 26 | 0.13% | 1 | 0.16% |
| Tavian Barnes | 26 | 0.13% | 1 | 0.16% |
| Goldwyn Rodrigues | 23 | 0.11% | 3 | 0.47% |
| Kirill A. Shutemov | 23 | 0.11% | 2 | 0.32% |
| David Woodhouse | 17 | 0.08% | 1 | 0.16% |
| Andrew Morton | 16 | 0.08% | 1 | 0.16% |
| Kent Overstreet | 15 | 0.07% | 3 | 0.47% |
| Dan Carpenter | 14 | 0.07% | 1 | 0.16% |
| Alexandre Oliva | 14 | 0.07% | 1 | 0.16% |
| Boris Burkov | 14 | 0.07% | 2 | 0.32% |
| Yan Zheng | 12 | 0.06% | 1 | 0.16% |
| Uros Bizjak | 9 | 0.04% | 1 | 0.16% |
| Stefan Behrens | 8 | 0.04% | 1 | 0.16% |
| Ira Weiny | 8 | 0.04% | 1 | 0.16% |
| Arne Jansen | 8 | 0.04% | 1 | 0.16% |
| Forrest Liu | 8 | 0.04% | 1 | 0.16% |
| Shilong Wang | 7 | 0.03% | 1 | 0.16% |
| Chengyu Song | 7 | 0.03% | 1 | 0.16% |
| Li Zefan | 6 | 0.03% | 3 | 0.47% |
| Anand Jain | 6 | 0.03% | 2 | 0.32% |
| Colin Ian King | 5 | 0.02% | 1 | 0.16% |
| Dennis Zhou | 5 | 0.02% | 1 | 0.16% |
| Dan Magenheimer | 5 | 0.02% | 1 | 0.16% |
| Xiao Jiang | 4 | 0.02% | 1 | 0.16% |
| Heiko Carstens | 4 | 0.02% | 1 | 0.16% |
| Jens Axboe | 4 | 0.02% | 1 | 0.16% |
| Irenge Jules Bashizi | 4 | 0.02% | 1 | 0.16% |
| Paul E. McKenney | 4 | 0.02% | 1 | 0.16% |
| Mel Gorman | 3 | 0.01% | 1 | 0.16% |
| Sven Wegener | 3 | 0.01% | 1 | 0.16% |
| Michal Hocko | 3 | 0.01% | 1 | 0.16% |
| Andi Kleen | 3 | 0.01% | 1 | 0.16% |
| Jan Kara | 2 | 0.01% | 1 | 0.16% |
| Elena Reshetova | 2 | 0.01% | 1 | 0.16% |
| Ming Lei | 1 | 0.00% | 1 | 0.16% |
| Randy Dunlap | 1 | 0.00% | 1 | 0.16% |
| Lu Fengqi | 1 | 0.00% | 1 | 0.16% |
| Nigel Christian | 1 | 0.00% | 1 | 0.16% |
| Tsutomu Itoh | 1 | 0.00% | 1 | 0.16% |
| Fanjun Kong | 1 | 0.00% | 1 | 0.16% |
| Minjie Du | 1 | 0.00% | 1 | 0.16% |
| Gabriel Niebler | 1 | 0.00% | 1 | 0.16% |
| Greg Kroah-Hartman | 1 | 0.00% | 1 | 0.16% |
| Neil Brown | 1 | 0.00% | 1 | 0.16% |
| Chengming Zhou | 1 | 0.00% | 1 | 0.16% |
| Total | 20465 | 634 |
// SPDX-License-Identifier: GPL-2.0 #include <linux/bitops.h> #include <linux/slab.h> #include <linux/bio.h> #include <linux/mm.h> #include <linux/pagemap.h> #include <linux/page-flags.h> #include <linux/sched/mm.h> #include <linux/spinlock.h> #include <linux/blkdev.h> #include <linux/swap.h> #include <linux/writeback.h> #include <linux/pagevec.h> #include <linux/prefetch.h> #include <linux/fsverity.h> #include "extent_io.h" #include "extent-io-tree.h" #include "extent_map.h" #include "ctree.h" #include "btrfs_inode.h" #include "bio.h" #include "locking.h" #include "backref.h" #include "disk-io.h" #include "subpage.h" #include "zoned.h" #include "block-group.h" #include "compression.h" #include "fs.h" #include "accessors.h" #include "file-item.h" #include "file.h" #include "dev-replace.h" #include "super.h" #include "transaction.h" static struct kmem_cache *extent_buffer_cache; #ifdef CONFIG_BTRFS_DEBUG static inline void btrfs_leak_debug_add_eb(struct extent_buffer *eb) { struct btrfs_fs_info *fs_info = eb->fs_info; unsigned long flags; spin_lock_irqsave(&fs_info->eb_leak_lock, flags); list_add(&eb->leak_list, &fs_info->allocated_ebs); spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags); } static inline void btrfs_leak_debug_del_eb(struct extent_buffer *eb) { struct btrfs_fs_info *fs_info = eb->fs_info; unsigned long flags; spin_lock_irqsave(&fs_info->eb_leak_lock, flags); list_del(&eb->leak_list); spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags); } void btrfs_extent_buffer_leak_debug_check(struct btrfs_fs_info *fs_info) { struct extent_buffer *eb; unsigned long flags; /* * If we didn't get into open_ctree our allocated_ebs will not be * initialized, so just skip this. */ if (!fs_info->allocated_ebs.next) return; WARN_ON(!list_empty(&fs_info->allocated_ebs)); spin_lock_irqsave(&fs_info->eb_leak_lock, flags); while (!list_empty(&fs_info->allocated_ebs)) { eb = list_first_entry(&fs_info->allocated_ebs, struct extent_buffer, leak_list); pr_err( "BTRFS: buffer leak start %llu len %u refs %d bflags %lu owner %llu\n", eb->start, eb->len, atomic_read(&eb->refs), eb->bflags, btrfs_header_owner(eb)); list_del(&eb->leak_list); WARN_ON_ONCE(1); kmem_cache_free(extent_buffer_cache, eb); } spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags); } #else #define btrfs_leak_debug_add_eb(eb) do {} while (0) #define btrfs_leak_debug_del_eb(eb) do {} while (0) #endif /* * Structure to record info about the bio being assembled, and other info like * how many bytes are there before stripe/ordered extent boundary. */ struct btrfs_bio_ctrl { struct btrfs_bio *bbio; enum btrfs_compression_type compress_type; u32 len_to_oe_boundary; blk_opf_t opf; btrfs_bio_end_io_t end_io_func; struct writeback_control *wbc; }; static void submit_one_bio(struct btrfs_bio_ctrl *bio_ctrl) { struct btrfs_bio *bbio = bio_ctrl->bbio; if (!bbio) return; /* Caller should ensure the bio has at least some range added */ ASSERT(bbio->bio.bi_iter.bi_size); if (btrfs_op(&bbio->bio) == BTRFS_MAP_READ && bio_ctrl->compress_type != BTRFS_COMPRESS_NONE) btrfs_submit_compressed_read(bbio); else btrfs_submit_bio(bbio, 0); /* The bbio is owned by the end_io handler now */ bio_ctrl->bbio = NULL; } /* * Submit or fail the current bio in the bio_ctrl structure. */ static void submit_write_bio(struct btrfs_bio_ctrl *bio_ctrl, int ret) { struct btrfs_bio *bbio = bio_ctrl->bbio; if (!bbio) return; if (ret) { ASSERT(ret < 0); btrfs_bio_end_io(bbio, errno_to_blk_status(ret)); /* The bio is owned by the end_io handler now */ bio_ctrl->bbio = NULL; } else { submit_one_bio(bio_ctrl); } } int __init extent_buffer_init_cachep(void) { extent_buffer_cache = kmem_cache_create("btrfs_extent_buffer", sizeof(struct extent_buffer), 0, 0, NULL); if (!extent_buffer_cache) return -ENOMEM; return 0; } void __cold extent_buffer_free_cachep(void) { /* * Make sure all delayed rcu free are flushed before we * destroy caches. */ rcu_barrier(); kmem_cache_destroy(extent_buffer_cache); } void extent_range_clear_dirty_for_io(struct inode *inode, u64 start, u64 end) { unsigned long index = start >> PAGE_SHIFT; unsigned long end_index = end >> PAGE_SHIFT; struct page *page; while (index <= end_index) { page = find_get_page(inode->i_mapping, index); BUG_ON(!page); /* Pages should be in the extent_io_tree */ clear_page_dirty_for_io(page); put_page(page); index++; } } static void process_one_page(struct btrfs_fs_info *fs_info, struct page *page, struct page *locked_page, unsigned long page_ops, u64 start, u64 end) { struct folio *folio = page_folio(page); u32 len; ASSERT(end + 1 - start != 0 && end + 1 - start < U32_MAX); len = end + 1 - start; if (page_ops & PAGE_SET_ORDERED) btrfs_folio_clamp_set_ordered(fs_info, folio, start, len); if (page_ops & PAGE_START_WRITEBACK) { btrfs_folio_clamp_clear_dirty(fs_info, folio, start, len); btrfs_folio_clamp_set_writeback(fs_info, folio, start, len); } if (page_ops & PAGE_END_WRITEBACK) btrfs_folio_clamp_clear_writeback(fs_info, folio, start, len); if (page != locked_page && (page_ops & PAGE_UNLOCK)) btrfs_folio_end_writer_lock(fs_info, folio, start, len); } static void __process_pages_contig(struct address_space *mapping, struct page *locked_page, u64 start, u64 end, unsigned long page_ops) { struct btrfs_fs_info *fs_info = inode_to_fs_info(mapping->host); pgoff_t start_index = start >> PAGE_SHIFT; pgoff_t end_index = end >> PAGE_SHIFT; pgoff_t index = start_index; struct folio_batch fbatch; int i; folio_batch_init(&fbatch); while (index <= end_index) { int found_folios; found_folios = filemap_get_folios_contig(mapping, &index, end_index, &fbatch); for (i = 0; i < found_folios; i++) { struct folio *folio = fbatch.folios[i]; process_one_page(fs_info, &folio->page, locked_page, page_ops, start, end); } folio_batch_release(&fbatch); cond_resched(); } } static noinline void __unlock_for_delalloc(struct inode *inode, struct page *locked_page, u64 start, u64 end) { unsigned long index = start >> PAGE_SHIFT; unsigned long end_index = end >> PAGE_SHIFT; ASSERT(locked_page); if (index == locked_page->index && end_index == index) return; __process_pages_contig(inode->i_mapping, locked_page, start, end, PAGE_UNLOCK); } static noinline int lock_delalloc_pages(struct inode *inode, struct page *locked_page, u64 start, u64 end) { struct btrfs_fs_info *fs_info = inode_to_fs_info(inode); struct address_space *mapping = inode->i_mapping; pgoff_t start_index = start >> PAGE_SHIFT; pgoff_t end_index = end >> PAGE_SHIFT; pgoff_t index = start_index; u64 processed_end = start; struct folio_batch fbatch; if (index == locked_page->index && index == end_index) return 0; folio_batch_init(&fbatch); while (index <= end_index) { unsigned int found_folios, i; found_folios = filemap_get_folios_contig(mapping, &index, end_index, &fbatch); if (found_folios == 0) goto out; for (i = 0; i < found_folios; i++) { struct folio *folio = fbatch.folios[i]; struct page *page = folio_page(folio, 0); u32 len = end + 1 - start; if (page == locked_page) continue; if (btrfs_folio_start_writer_lock(fs_info, folio, start, len)) goto out; if (!PageDirty(page) || page->mapping != mapping) { btrfs_folio_end_writer_lock(fs_info, folio, start, len); goto out; } processed_end = page_offset(page) + PAGE_SIZE - 1; } folio_batch_release(&fbatch); cond_resched(); } return 0; out: folio_batch_release(&fbatch); if (processed_end > start) __unlock_for_delalloc(inode, locked_page, start, processed_end); return -EAGAIN; } /* * Find and lock a contiguous range of bytes in the file marked as delalloc, no * more than @max_bytes. * * @start: The original start bytenr to search. * Will store the extent range start bytenr. * @end: The original end bytenr of the search range * Will store the extent range end bytenr. * * Return true if we find a delalloc range which starts inside the original * range, and @start/@end will store the delalloc range start/end. * * Return false if we can't find any delalloc range which starts inside the * original range, and @start/@end will be the non-delalloc range start/end. */ EXPORT_FOR_TESTS noinline_for_stack bool find_lock_delalloc_range(struct inode *inode, struct page *locked_page, u64 *start, u64 *end) { struct btrfs_fs_info *fs_info = inode_to_fs_info(inode); struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree; const u64 orig_start = *start; const u64 orig_end = *end; /* The sanity tests may not set a valid fs_info. */ u64 max_bytes = fs_info ? fs_info->max_extent_size : BTRFS_MAX_EXTENT_SIZE; u64 delalloc_start; u64 delalloc_end; bool found; struct extent_state *cached_state = NULL; int ret; int loops = 0; /* Caller should pass a valid @end to indicate the search range end */ ASSERT(orig_end > orig_start); /* The range should at least cover part of the page */ ASSERT(!(orig_start >= page_offset(locked_page) + PAGE_SIZE || orig_end <= page_offset(locked_page))); again: /* step one, find a bunch of delalloc bytes starting at start */ delalloc_start = *start; delalloc_end = 0; found = btrfs_find_delalloc_range(tree, &delalloc_start, &delalloc_end, max_bytes, &cached_state); if (!found || delalloc_end <= *start || delalloc_start > orig_end) { *start = delalloc_start; /* @delalloc_end can be -1, never go beyond @orig_end */ *end = min(delalloc_end, orig_end); free_extent_state(cached_state); return false; } /* * start comes from the offset of locked_page. We have to lock * pages in order, so we can't process delalloc bytes before * locked_page */ if (delalloc_start < *start) delalloc_start = *start; /* * make sure to limit the number of pages we try to lock down */ if (delalloc_end + 1 - delalloc_start > max_bytes) delalloc_end = delalloc_start + max_bytes - 1; /* step two, lock all the pages after the page that has start */ ret = lock_delalloc_pages(inode, locked_page, delalloc_start, delalloc_end); ASSERT(!ret || ret == -EAGAIN); if (ret == -EAGAIN) { /* some of the pages are gone, lets avoid looping by * shortening the size of the delalloc range we're searching */ free_extent_state(cached_state); cached_state = NULL; if (!loops) { max_bytes = PAGE_SIZE; loops = 1; goto again; } else { found = false; goto out_failed; } } /* step three, lock the state bits for the whole range */ lock_extent(tree, delalloc_start, delalloc_end, &cached_state); /* then test to make sure it is all still delalloc */ ret = test_range_bit(tree, delalloc_start, delalloc_end, EXTENT_DELALLOC, cached_state); if (!ret) { unlock_extent(tree, delalloc_start, delalloc_end, &cached_state); __unlock_for_delalloc(inode, locked_page, delalloc_start, delalloc_end); cond_resched(); goto again; } free_extent_state(cached_state); *start = delalloc_start; *end = delalloc_end; out_failed: return found; } void extent_clear_unlock_delalloc(struct btrfs_inode *inode, u64 start, u64 end, struct page *locked_page, u32 clear_bits, unsigned long page_ops) { clear_extent_bit(&inode->io_tree, start, end, clear_bits, NULL); __process_pages_contig(inode->vfs_inode.i_mapping, locked_page, start, end, page_ops); } static bool btrfs_verify_page(struct page *page, u64 start) { if (!fsverity_active(page->mapping->host) || PageUptodate(page) || start >= i_size_read(page->mapping->host)) return true; return fsverity_verify_page(page); } static void end_page_read(struct page *page, bool uptodate, u64 start, u32 len) { struct btrfs_fs_info *fs_info = page_to_fs_info(page); struct folio *folio = page_folio(page); ASSERT(page_offset(page) <= start && start + len <= page_offset(page) + PAGE_SIZE); if (uptodate && btrfs_verify_page(page, start)) btrfs_folio_set_uptodate(fs_info, folio, start, len); else btrfs_folio_clear_uptodate(fs_info, folio, start, len); if (!btrfs_is_subpage(fs_info, page->mapping)) unlock_page(page); else btrfs_subpage_end_reader(fs_info, folio, start, len); } /* * After a write IO is done, we need to: * * - clear the uptodate bits on error * - clear the writeback bits in the extent tree for the range * - filio_end_writeback() if there is no more pending io for the folio * * Scheduling is not allowed, so the extent state tree is expected * to have one and only one object corresponding to this IO. */ static void end_bbio_data_write(struct btrfs_bio *bbio) { struct btrfs_fs_info *fs_info = bbio->fs_info; struct bio *bio = &bbio->bio; int error = blk_status_to_errno(bio->bi_status); struct folio_iter fi; const u32 sectorsize = fs_info->sectorsize; ASSERT(!bio_flagged(bio, BIO_CLONED)); bio_for_each_folio_all(fi, bio) { struct folio *folio = fi.folio; u64 start = folio_pos(folio) + fi.offset; u32 len = fi.length; /* Only order 0 (single page) folios are allowed for data. */ ASSERT(folio_order(folio) == 0); /* Our read/write should always be sector aligned. */ if (!IS_ALIGNED(fi.offset, sectorsize)) btrfs_err(fs_info, "partial page write in btrfs with offset %zu and length %zu", fi.offset, fi.length); else if (!IS_ALIGNED(fi.length, sectorsize)) btrfs_info(fs_info, "incomplete page write with offset %zu and length %zu", fi.offset, fi.length); btrfs_finish_ordered_extent(bbio->ordered, folio_page(folio, 0), start, len, !error); if (error) mapping_set_error(folio->mapping, error); btrfs_folio_clear_writeback(fs_info, folio, start, len); } bio_put(bio); } /* * Record previously processed extent range * * For endio_readpage_release_extent() to handle a full extent range, reducing * the extent io operations. */ struct processed_extent { struct btrfs_inode *inode; /* Start of the range in @inode */ u64 start; /* End of the range in @inode */ u64 end; bool uptodate; }; /* * Try to release processed extent range * * May not release the extent range right now if the current range is * contiguous to processed extent. * * Will release processed extent when any of @inode, @uptodate, the range is * no longer contiguous to the processed range. * * Passing @inode == NULL will force processed extent to be released. */ static void endio_readpage_release_extent(struct processed_extent *processed, struct btrfs_inode *inode, u64 start, u64 end, bool uptodate) { struct extent_state *cached = NULL; struct extent_io_tree *tree; /* The first extent, initialize @processed */ if (!processed->inode) goto update; /* * Contiguous to processed extent, just uptodate the end. * * Several things to notice: * * - bio can be merged as long as on-disk bytenr is contiguous * This means we can have page belonging to other inodes, thus need to * check if the inode still matches. * - bvec can contain range beyond current page for multi-page bvec * Thus we need to do processed->end + 1 >= start check */ if (processed->inode == inode && processed->uptodate == uptodate && processed->end + 1 >= start && end >= processed->end) { processed->end = end; return; } tree = &processed->inode->io_tree; /* * Now we don't have range contiguous to the processed range, release * the processed range now. */ unlock_extent(tree, processed->start, processed->end, &cached); update: /* Update processed to current range */ processed->inode = inode; processed->start = start; processed->end = end; processed->uptodate = uptodate; } static void begin_page_read(struct btrfs_fs_info *fs_info, struct page *page) { struct folio *folio = page_folio(page); ASSERT(folio_test_locked(folio)); if (!btrfs_is_subpage(fs_info, folio->mapping)) return; ASSERT(folio_test_private(folio)); btrfs_subpage_start_reader(fs_info, folio, page_offset(page), PAGE_SIZE); } /* * After a data read IO is done, we need to: * * - clear the uptodate bits on error * - set the uptodate bits if things worked * - set the folio up to date if all extents in the tree are uptodate * - clear the lock bit in the extent tree * - unlock the folio if there are no other extents locked for it * * Scheduling is not allowed, so the extent state tree is expected * to have one and only one object corresponding to this IO. */ static void end_bbio_data_read(struct btrfs_bio *bbio) { struct btrfs_fs_info *fs_info = bbio->fs_info; struct bio *bio = &bbio->bio; struct processed_extent processed = { 0 }; struct folio_iter fi; const u32 sectorsize = fs_info->sectorsize; ASSERT(!bio_flagged(bio, BIO_CLONED)); bio_for_each_folio_all(fi, &bbio->bio) { bool uptodate = !bio->bi_status; struct folio *folio = fi.folio; struct inode *inode = folio->mapping->host; u64 start; u64 end; u32 len; /* For now only order 0 folios are supported for data. */ ASSERT(folio_order(folio) == 0); btrfs_debug(fs_info, "%s: bi_sector=%llu, err=%d, mirror=%u", __func__, bio->bi_iter.bi_sector, bio->bi_status, bbio->mirror_num); /* * We always issue full-sector reads, but if some block in a * folio fails to read, blk_update_request() will advance * bv_offset and adjust bv_len to compensate. Print a warning * for unaligned offsets, and an error if they don't add up to * a full sector. */ if (!IS_ALIGNED(fi.offset, sectorsize)) btrfs_err(fs_info, "partial page read in btrfs with offset %zu and length %zu", fi.offset, fi.length); else if (!IS_ALIGNED(fi.offset + fi.length, sectorsize)) btrfs_info(fs_info, "incomplete page read with offset %zu and length %zu", fi.offset, fi.length); start = folio_pos(folio) + fi.offset; end = start + fi.length - 1; len = fi.length; if (likely(uptodate)) { loff_t i_size = i_size_read(inode); pgoff_t end_index = i_size >> folio_shift(folio); /* * Zero out the remaining part if this range straddles * i_size. * * Here we should only zero the range inside the folio, * not touch anything else. * * NOTE: i_size is exclusive while end is inclusive. */ if (folio_index(folio) == end_index && i_size <= end) { u32 zero_start = max(offset_in_folio(folio, i_size), offset_in_folio(folio, start)); u32 zero_len = offset_in_folio(folio, end) + 1 - zero_start; folio_zero_range(folio, zero_start, zero_len); } } /* Update page status and unlock. */ end_page_read(folio_page(folio, 0), uptodate, start, len); endio_readpage_release_extent(&processed, BTRFS_I(inode), start, end, uptodate); } /* Release the last extent */ endio_readpage_release_extent(&processed, NULL, 0, 0, false); bio_put(bio); } /* * Populate every free slot in a provided array with pages. * * @nr_pages: number of pages to allocate * @page_array: the array to fill with pages; any existing non-null entries in * the array will be skipped * @extra_gfp: the extra GFP flags for the allocation. * * Return: 0 if all pages were able to be allocated; * -ENOMEM otherwise, the partially allocated pages would be freed and * the array slots zeroed */ int btrfs_alloc_page_array(unsigned int nr_pages, struct page **page_array, gfp_t extra_gfp) { const gfp_t gfp = GFP_NOFS | extra_gfp; unsigned int allocated; for (allocated = 0; allocated < nr_pages;) { unsigned int last = allocated; allocated = alloc_pages_bulk_array(gfp, nr_pages, page_array); if (unlikely(allocated == last)) { /* No progress, fail and do cleanup. */ for (int i = 0; i < allocated; i++) { __free_page(page_array[i]); page_array[i] = NULL; } return -ENOMEM; } } return 0; } /* * Populate needed folios for the extent buffer. * * For now, the folios populated are always in order 0 (aka, single page). */ static int alloc_eb_folio_array(struct extent_buffer *eb, gfp_t extra_gfp) { struct page *page_array[INLINE_EXTENT_BUFFER_PAGES] = { 0 }; int num_pages = num_extent_pages(eb); int ret; ret = btrfs_alloc_page_array(num_pages, page_array, extra_gfp); if (ret < 0) return ret; for (int i = 0; i < num_pages; i++) eb->folios[i] = page_folio(page_array[i]); eb->folio_size = PAGE_SIZE; eb->folio_shift = PAGE_SHIFT; return 0; } static bool btrfs_bio_is_contig(struct btrfs_bio_ctrl *bio_ctrl, struct page *page, u64 disk_bytenr, unsigned int pg_offset) { struct bio *bio = &bio_ctrl->bbio->bio; struct bio_vec *bvec = bio_last_bvec_all(bio); const sector_t sector = disk_bytenr >> SECTOR_SHIFT; if (bio_ctrl->compress_type != BTRFS_COMPRESS_NONE) { /* * For compression, all IO should have its logical bytenr set * to the starting bytenr of the compressed extent. */ return bio->bi_iter.bi_sector == sector; } /* * The contig check requires the following conditions to be met: * * 1) The pages are belonging to the same inode * This is implied by the call chain. * * 2) The range has adjacent logical bytenr * * 3) The range has adjacent file offset * This is required for the usage of btrfs_bio->file_offset. */ return bio_end_sector(bio) == sector && page_offset(bvec->bv_page) + bvec->bv_offset + bvec->bv_len == page_offset(page) + pg_offset; } static void alloc_new_bio(struct btrfs_inode *inode, struct btrfs_bio_ctrl *bio_ctrl, u64 disk_bytenr, u64 file_offset) { struct btrfs_fs_info *fs_info = inode->root->fs_info; struct btrfs_bio *bbio; bbio = btrfs_bio_alloc(BIO_MAX_VECS, bio_ctrl->opf, fs_info, bio_ctrl->end_io_func, NULL); bbio->bio.bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT; bbio->inode = inode; bbio->file_offset = file_offset; bio_ctrl->bbio = bbio; bio_ctrl->len_to_oe_boundary = U32_MAX; /* Limit data write bios to the ordered boundary. */ if (bio_ctrl->wbc) { struct btrfs_ordered_extent *ordered; ordered = btrfs_lookup_ordered_extent(inode, file_offset); if (ordered) { bio_ctrl->len_to_oe_boundary = min_t(u32, U32_MAX, ordered->file_offset + ordered->disk_num_bytes - file_offset); bbio->ordered = ordered; } /* * Pick the last added device to support cgroup writeback. For * multi-device file systems this means blk-cgroup policies have * to always be set on the last added/replaced device. * This is a bit odd but has been like that for a long time. */ bio_set_dev(&bbio->bio, fs_info->fs_devices->latest_dev->bdev); wbc_init_bio(bio_ctrl->wbc, &bbio->bio); } } /* * @disk_bytenr: logical bytenr where the write will be * @page: page to add to the bio * @size: portion of page that we want to write to * @pg_offset: offset of the new bio or to check whether we are adding * a contiguous page to the previous one * * The will either add the page into the existing @bio_ctrl->bbio, or allocate a * new one in @bio_ctrl->bbio. * The mirror number for this IO should already be initizlied in * @bio_ctrl->mirror_num. */ static void submit_extent_page(struct btrfs_bio_ctrl *bio_ctrl, u64 disk_bytenr, struct page *page, size_t size, unsigned long pg_offset) { struct btrfs_inode *inode = page_to_inode(page); ASSERT(pg_offset + size <= PAGE_SIZE); ASSERT(bio_ctrl->end_io_func); if (bio_ctrl->bbio && !btrfs_bio_is_contig(bio_ctrl, page, disk_bytenr, pg_offset)) submit_one_bio(bio_ctrl); do { u32 len = size; /* Allocate new bio if needed */ if (!bio_ctrl->bbio) { alloc_new_bio(inode, bio_ctrl, disk_bytenr, page_offset(page) + pg_offset); } /* Cap to the current ordered extent boundary if there is one. */ if (len > bio_ctrl->len_to_oe_boundary) { ASSERT(bio_ctrl->compress_type == BTRFS_COMPRESS_NONE); ASSERT(is_data_inode(&inode->vfs_inode)); len = bio_ctrl->len_to_oe_boundary; } if (bio_add_page(&bio_ctrl->bbio->bio, page, len, pg_offset) != len) { /* bio full: move on to a new one */ submit_one_bio(bio_ctrl); continue; } if (bio_ctrl->wbc) wbc_account_cgroup_owner(bio_ctrl->wbc, page, len); size -= len; pg_offset += len; disk_bytenr += len; /* * len_to_oe_boundary defaults to U32_MAX, which isn't page or * sector aligned. alloc_new_bio() then sets it to the end of * our ordered extent for writes into zoned devices. * * When len_to_oe_boundary is tracking an ordered extent, we * trust the ordered extent code to align things properly, and * the check above to cap our write to the ordered extent * boundary is correct. * * When len_to_oe_boundary is U32_MAX, the cap above would * result in a 4095 byte IO for the last page right before * we hit the bio limit of UINT_MAX. bio_add_page() has all * the checks required to make sure we don't overflow the bio, * and we should just ignore len_to_oe_boundary completely * unless we're using it to track an ordered extent. * * It's pretty hard to make a bio sized U32_MAX, but it can * happen when the page cache is able to feed us contiguous * pages for large extents. */ if (bio_ctrl->len_to_oe_boundary != U32_MAX) bio_ctrl->len_to_oe_boundary -= len; /* Ordered extent boundary: move on to a new bio. */ if (bio_ctrl->len_to_oe_boundary == 0) submit_one_bio(bio_ctrl); } while (size); } static int attach_extent_buffer_folio(struct extent_buffer *eb, struct folio *folio, struct btrfs_subpage *prealloc) { struct btrfs_fs_info *fs_info = eb->fs_info; int ret = 0; /* * If the page is mapped to btree inode, we should hold the private * lock to prevent race. * For cloned or dummy extent buffers, their pages are not mapped and * will not race with any other ebs. */ if (folio->mapping) lockdep_assert_held(&folio->mapping->i_private_lock); if (fs_info->nodesize >= PAGE_SIZE) { if (!folio_test_private(folio)) folio_attach_private(folio, eb); else WARN_ON(folio_get_private(folio) != eb); return 0; } /* Already mapped, just free prealloc */ if (folio_test_private(folio)) { btrfs_free_subpage(prealloc); return 0; } if (prealloc) /* Has preallocated memory for subpage */ folio_attach_private(folio, prealloc); else /* Do new allocation to attach subpage */ ret = btrfs_attach_subpage(fs_info, folio, BTRFS_SUBPAGE_METADATA); return ret; } int set_page_extent_mapped(struct page *page) { return set_folio_extent_mapped(page_folio(page)); } int set_folio_extent_mapped(struct folio *folio) { struct btrfs_fs_info *fs_info; ASSERT(folio->mapping); if (folio_test_private(folio)) return 0; fs_info = folio_to_fs_info(folio); if (btrfs_is_subpage(fs_info, folio->mapping)) return btrfs_attach_subpage(fs_info, folio, BTRFS_SUBPAGE_DATA); folio_attach_private(folio, (void *)EXTENT_FOLIO_PRIVATE); return 0; } void clear_page_extent_mapped(struct page *page) { struct folio *folio = page_folio(page); struct btrfs_fs_info *fs_info; ASSERT(page->mapping); if (!folio_test_private(folio)) return; fs_info = page_to_fs_info(page); if (btrfs_is_subpage(fs_info, page->mapping)) return btrfs_detach_subpage(fs_info, folio); folio_detach_private(folio); } static struct extent_map *__get_extent_map(struct inode *inode, struct page *page, u64 start, u64 len, struct extent_map **em_cached) { struct extent_map *em; ASSERT(em_cached); if (*em_cached) { em = *em_cached; if (extent_map_in_tree(em) && start >= em->start && start < extent_map_end(em)) { refcount_inc(&em->refs); return em; } free_extent_map(em); *em_cached = NULL; } em = btrfs_get_extent(BTRFS_I(inode), page, start, len); if (!IS_ERR(em)) { BUG_ON(*em_cached); refcount_inc(&em->refs); *em_cached = em; } return em; } /* * basic readpage implementation. Locked extent state structs are inserted * into the tree that are removed when the IO is done (by the end_io * handlers) * XXX JDM: This needs looking at to ensure proper page locking * return 0 on success, otherwise return error */ static int btrfs_do_readpage(struct page *page, struct extent_map **em_cached, struct btrfs_bio_ctrl *bio_ctrl, u64 *prev_em_start) { struct inode *inode = page->mapping->host; struct btrfs_fs_info *fs_info = inode_to_fs_info(inode); u64 start = page_offset(page); const u64 end = start + PAGE_SIZE - 1; u64 cur = start; u64 extent_offset; u64 last_byte = i_size_read(inode); u64 block_start; struct extent_map *em; int ret = 0; size_t pg_offset = 0; size_t iosize; size_t blocksize = fs_info->sectorsize; struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree; ret = set_page_extent_mapped(page); if (ret < 0) { unlock_extent(tree, start, end, NULL); unlock_page(page); return ret; } if (page->index == last_byte >> PAGE_SHIFT) { size_t zero_offset = offset_in_page(last_byte); if (zero_offset) { iosize = PAGE_SIZE - zero_offset; memzero_page(page, zero_offset, iosize); } } bio_ctrl->end_io_func = end_bbio_data_read; begin_page_read(fs_info, page); while (cur <= end) { enum btrfs_compression_type compress_type = BTRFS_COMPRESS_NONE; bool force_bio_submit = false; u64 disk_bytenr; ASSERT(IS_ALIGNED(cur, fs_info->sectorsize)); if (cur >= last_byte) { iosize = PAGE_SIZE - pg_offset; memzero_page(page, pg_offset, iosize); unlock_extent(tree, cur, cur + iosize - 1, NULL); end_page_read(page, true, cur, iosize); break; } em = __get_extent_map(inode, page, cur, end - cur + 1, em_cached); if (IS_ERR(em)) { unlock_extent(tree, cur, end, NULL); end_page_read(page, false, cur, end + 1 - cur); return PTR_ERR(em); } extent_offset = cur - em->start; BUG_ON(extent_map_end(em) <= cur); BUG_ON(end < cur); compress_type = extent_map_compression(em); iosize = min(extent_map_end(em) - cur, end - cur + 1); iosize = ALIGN(iosize, blocksize); if (compress_type != BTRFS_COMPRESS_NONE) disk_bytenr = em->block_start; else disk_bytenr = em->block_start + extent_offset; block_start = em->block_start; if (em->flags & EXTENT_FLAG_PREALLOC) block_start = EXTENT_MAP_HOLE; /* * If we have a file range that points to a compressed extent * and it's followed by a consecutive file range that points * to the same compressed extent (possibly with a different * offset and/or length, so it either points to the whole extent * or only part of it), we must make sure we do not submit a * single bio to populate the pages for the 2 ranges because * this makes the compressed extent read zero out the pages * belonging to the 2nd range. Imagine the following scenario: * * File layout * [0 - 8K] [8K - 24K] * | | * | | * points to extent X, points to extent X, * offset 4K, length of 8K offset 0, length 16K * * [extent X, compressed length = 4K uncompressed length = 16K] * * If the bio to read the compressed extent covers both ranges, * it will decompress extent X into the pages belonging to the * first range and then it will stop, zeroing out the remaining * pages that belong to the other range that points to extent X. * So here we make sure we submit 2 bios, one for the first * range and another one for the third range. Both will target * the same physical extent from disk, but we can't currently * make the compressed bio endio callback populate the pages * for both ranges because each compressed bio is tightly * coupled with a single extent map, and each range can have * an extent map with a different offset value relative to the * uncompressed data of our extent and different lengths. This * is a corner case so we prioritize correctness over * non-optimal behavior (submitting 2 bios for the same extent). */ if (compress_type != BTRFS_COMPRESS_NONE && prev_em_start && *prev_em_start != (u64)-1 && *prev_em_start != em->start) force_bio_submit = true; if (prev_em_start) *prev_em_start = em->start; free_extent_map(em); em = NULL; /* we've found a hole, just zero and go on */ if (block_start == EXTENT_MAP_HOLE) { memzero_page(page, pg_offset, iosize); unlock_extent(tree, cur, cur + iosize - 1, NULL); end_page_read(page, true, cur, iosize); cur = cur + iosize; pg_offset += iosize; continue; } /* the get_extent function already copied into the page */ if (block_start == EXTENT_MAP_INLINE) { unlock_extent(tree, cur, cur + iosize - 1, NULL); end_page_read(page, true, cur, iosize); cur = cur + iosize; pg_offset += iosize; continue; } if (bio_ctrl->compress_type != compress_type) { submit_one_bio(bio_ctrl); bio_ctrl->compress_type = compress_type; } if (force_bio_submit) submit_one_bio(bio_ctrl); submit_extent_page(bio_ctrl, disk_bytenr, page, iosize, pg_offset); cur = cur + iosize; pg_offset += iosize; } return 0; } int btrfs_read_folio(struct file *file, struct folio *folio) { struct page *page = &folio->page; struct btrfs_inode *inode = page_to_inode(page); u64 start = page_offset(page); u64 end = start + PAGE_SIZE - 1; struct btrfs_bio_ctrl bio_ctrl = { .opf = REQ_OP_READ }; struct extent_map *em_cached = NULL; int ret; btrfs_lock_and_flush_ordered_range(inode, start, end, NULL); ret = btrfs_do_readpage(page, &em_cached, &bio_ctrl, NULL); free_extent_map(em_cached); /* * If btrfs_do_readpage() failed we will want to submit the assembled * bio to do the cleanup. */ submit_one_bio(&bio_ctrl); return ret; } static inline void contiguous_readpages(struct page *pages[], int nr_pages, u64 start, u64 end, struct extent_map **em_cached, struct btrfs_bio_ctrl *bio_ctrl, u64 *prev_em_start) { struct btrfs_inode *inode = page_to_inode(pages[0]); int index; ASSERT(em_cached); btrfs_lock_and_flush_ordered_range(inode, start, end, NULL); for (index = 0; index < nr_pages; index++) { btrfs_do_readpage(pages[index], em_cached, bio_ctrl, prev_em_start); put_page(pages[index]); } } /* * helper for __extent_writepage, doing all of the delayed allocation setup. * * This returns 1 if btrfs_run_delalloc_range function did all the work required * to write the page (copy into inline extent). In this case the IO has * been started and the page is already unlocked. * * This returns 0 if all went well (page still locked) * This returns < 0 if there were errors (page still locked) */ static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode, struct page *page, struct writeback_control *wbc) { const u64 page_start = page_offset(page); const u64 page_end = page_start + PAGE_SIZE - 1; u64 delalloc_start = page_start; u64 delalloc_end = page_end; u64 delalloc_to_write = 0; int ret = 0; while (delalloc_start < page_end) { delalloc_end = page_end; if (!find_lock_delalloc_range(&inode->vfs_inode, page, &delalloc_start, &delalloc_end)) { delalloc_start = delalloc_end + 1; continue; } ret = btrfs_run_delalloc_range(inode, page, delalloc_start, delalloc_end, wbc); if (ret < 0) return ret; delalloc_start = delalloc_end + 1; } /* * delalloc_end is already one less than the total length, so * we don't subtract one from PAGE_SIZE */ delalloc_to_write += DIV_ROUND_UP(delalloc_end + 1 - page_start, PAGE_SIZE); /* * If btrfs_run_dealloc_range() already started I/O and unlocked * the pages, we just need to account for them here. */ if (ret == 1) { wbc->nr_to_write -= delalloc_to_write; return 1; } if (wbc->nr_to_write < delalloc_to_write) { int thresh = 8192; if (delalloc_to_write < thresh * 2) thresh = delalloc_to_write; wbc->nr_to_write = min_t(u64, delalloc_to_write, thresh); } return 0; } /* * Find the first byte we need to write. * * For subpage, one page can contain several sectors, and * __extent_writepage_io() will just grab all extent maps in the page * range and try to submit all non-inline/non-compressed extents. * * This is a big problem for subpage, we shouldn't re-submit already written * data at all. * This function will lookup subpage dirty bit to find which range we really * need to submit. * * Return the next dirty range in [@start, @end). * If no dirty range is found, @start will be page_offset(page) + PAGE_SIZE. */ static void find_next_dirty_byte(struct btrfs_fs_info *fs_info, struct page *page, u64 *start, u64 *end) { struct folio *folio = page_folio(page); struct btrfs_subpage *subpage = folio_get_private(folio); struct btrfs_subpage_info *spi = fs_info->subpage_info; u64 orig_start = *start; /* Declare as unsigned long so we can use bitmap ops */ unsigned long flags; int range_start_bit; int range_end_bit; /* * For regular sector size == page size case, since one page only * contains one sector, we return the page offset directly. */ if (!btrfs_is_subpage(fs_info, page->mapping)) { *start = page_offset(page); *end = page_offset(page) + PAGE_SIZE; return; } range_start_bit = spi->dirty_offset + (offset_in_page(orig_start) >> fs_info->sectorsize_bits); /* We should have the page locked, but just in case */ spin_lock_irqsave(&subpage->lock, flags); bitmap_next_set_region(subpage->bitmaps, &range_start_bit, &range_end_bit, spi->dirty_offset + spi->bitmap_nr_bits); spin_unlock_irqrestore(&subpage->lock, flags); range_start_bit -= spi->dirty_offset; range_end_bit -= spi->dirty_offset; *start = page_offset(page) + range_start_bit * fs_info->sectorsize; *end = page_offset(page) + range_end_bit * fs_info->sectorsize; } /* * helper for __extent_writepage. This calls the writepage start hooks, * and does the loop to map the page into extents and bios. * * We return 1 if the IO is started and the page is unlocked, * 0 if all went well (page still locked) * < 0 if there were errors (page still locked) */ static noinline_for_stack int __extent_writepage_io(struct btrfs_inode *inode, struct page *page, struct btrfs_bio_ctrl *bio_ctrl, loff_t i_size, int *nr_ret) { struct btrfs_fs_info *fs_info = inode->root->fs_info; u64 cur = page_offset(page); u64 end = cur + PAGE_SIZE - 1; u64 extent_offset; u64 block_start; struct extent_map *em; int ret = 0; int nr = 0; ret = btrfs_writepage_cow_fixup(page); if (ret) { /* Fixup worker will requeue */ redirty_page_for_writepage(bio_ctrl->wbc, page); unlock_page(page); return 1; } bio_ctrl->end_io_func = end_bbio_data_write; while (cur <= end) { u32 len = end - cur + 1; u64 disk_bytenr; u64 em_end; u64 dirty_range_start = cur; u64 dirty_range_end; u32 iosize; if (cur >= i_size) { btrfs_mark_ordered_io_finished(inode, page, cur, len, true); /* * This range is beyond i_size, thus we don't need to * bother writing back. * But we still need to clear the dirty subpage bit, or * the next time the page gets dirtied, we will try to * writeback the sectors with subpage dirty bits, * causing writeback without ordered extent. */ btrfs_folio_clear_dirty(fs_info, page_folio(page), cur, len); break; } find_next_dirty_byte(fs_info, page, &dirty_range_start, &dirty_range_end); if (cur < dirty_range_start) { cur = dirty_range_start; continue; } em = btrfs_get_extent(inode, NULL, cur, len); if (IS_ERR(em)) { ret = PTR_ERR_OR_ZERO(em); goto out_error; } extent_offset = cur - em->start; em_end = extent_map_end(em); ASSERT(cur <= em_end); ASSERT(cur < end); ASSERT(IS_ALIGNED(em->start, fs_info->sectorsize)); ASSERT(IS_ALIGNED(em->len, fs_info->sectorsize)); block_start = em->block_start; disk_bytenr = em->block_start + extent_offset; ASSERT(!extent_map_is_compressed(em)); ASSERT(block_start != EXTENT_MAP_HOLE); ASSERT(block_start != EXTENT_MAP_INLINE); /* * Note that em_end from extent_map_end() and dirty_range_end from * find_next_dirty_byte() are all exclusive */ iosize = min(min(em_end, end + 1), dirty_range_end) - cur; free_extent_map(em); em = NULL; btrfs_set_range_writeback(inode, cur, cur + iosize - 1); if (!PageWriteback(page)) { btrfs_err(inode->root->fs_info, "page %lu not writeback, cur %llu end %llu", page->index, cur, end); } /* * Although the PageDirty bit is cleared before entering this * function, subpage dirty bit is not cleared. * So clear subpage dirty bit here so next time we won't submit * page for range already written to disk. */ btrfs_folio_clear_dirty(fs_info, page_folio(page), cur, iosize); submit_extent_page(bio_ctrl, disk_bytenr, page, iosize, cur - page_offset(page)); cur += iosize; nr++; } btrfs_folio_assert_not_dirty(fs_info, page_folio(page)); *nr_ret = nr; return 0; out_error: /* * If we finish without problem, we should not only clear page dirty, * but also empty subpage dirty bits */ *nr_ret = nr; return ret; } /* * the writepage semantics are similar to regular writepage. extent * records are inserted to lock ranges in the tree, and as dirty areas * are found, they are marked writeback. Then the lock bits are removed * and the end_io handler clears the writeback ranges * * Return 0 if everything goes well. * Return <0 for error. */ static int __extent_writepage(struct page *page, struct btrfs_bio_ctrl *bio_ctrl) { struct folio *folio = page_folio(page); struct inode *inode = page->mapping->host; const u64 page_start = page_offset(page); int ret; int nr = 0; size_t pg_offset; loff_t i_size = i_size_read(inode); unsigned long end_index = i_size >> PAGE_SHIFT; trace___extent_writepage(page, inode, bio_ctrl->wbc); WARN_ON(!PageLocked(page)); pg_offset = offset_in_page(i_size); if (page->index > end_index || (page->index == end_index && !pg_offset)) { folio_invalidate(folio, 0, folio_size(folio)); folio_unlock(folio); return 0; } if (page->index == end_index) memzero_page(page, pg_offset, PAGE_SIZE - pg_offset); ret = set_page_extent_mapped(page); if (ret < 0) goto done; ret = writepage_delalloc(BTRFS_I(inode), page, bio_ctrl->wbc); if (ret == 1) return 0; if (ret) goto done; ret = __extent_writepage_io(BTRFS_I(inode), page, bio_ctrl, i_size, &nr); if (ret == 1) return 0; bio_ctrl->wbc->nr_to_write--; done: if (nr == 0) { /* make sure the mapping tag for page dirty gets cleared */ set_page_writeback(page); end_page_writeback(page); } if (ret) { btrfs_mark_ordered_io_finished(BTRFS_I(inode), page, page_start, PAGE_SIZE, !ret); mapping_set_error(page->mapping, ret); } unlock_page(page); ASSERT(ret <= 0); return ret; } void wait_on_extent_buffer_writeback(struct extent_buffer *eb) { wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_WRITEBACK, TASK_UNINTERRUPTIBLE); } /* * Lock extent buffer status and pages for writeback. * * Return %false if the extent buffer doesn't need to be submitted (e.g. the * extent buffer is not dirty) * Return %true is the extent buffer is submitted to bio. */ static noinline_for_stack bool lock_extent_buffer_for_io(struct extent_buffer *eb, struct writeback_control *wbc) { struct btrfs_fs_info *fs_info = eb->fs_info; bool ret = false; btrfs_tree_lock(eb); while (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)) { btrfs_tree_unlock(eb); if (wbc->sync_mode != WB_SYNC_ALL) return false; wait_on_extent_buffer_writeback(eb); btrfs_tree_lock(eb); } /* * We need to do this to prevent races in people who check if the eb is * under IO since we can end up having no IO bits set for a short period * of time. */ spin_lock(&eb->refs_lock); if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) { set_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags); spin_unlock(&eb->refs_lock); btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN); percpu_counter_add_batch(&fs_info->dirty_metadata_bytes, -eb->len, fs_info->dirty_metadata_batch); ret = true; } else { spin_unlock(&eb->refs_lock); } btrfs_tree_unlock(eb); return ret; } static void set_btree_ioerr(struct extent_buffer *eb) { struct btrfs_fs_info *fs_info = eb->fs_info; set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags); /* * A read may stumble upon this buffer later, make sure that it gets an * error and knows there was an error. */ clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); /* * We need to set the mapping with the io error as well because a write * error will flip the file system readonly, and then syncfs() will * return a 0 because we are readonly if we don't modify the err seq for * the superblock. */ mapping_set_error(eb->fs_info->btree_inode->i_mapping, -EIO); /* * If writeback for a btree extent that doesn't belong to a log tree * failed, increment the counter transaction->eb_write_errors. * We do this because while the transaction is running and before it's * committing (when we call filemap_fdata[write|wait]_range against * the btree inode), we might have * btree_inode->i_mapping->a_ops->writepages() called by the VM - if it * returns an error or an error happens during writeback, when we're * committing the transaction we wouldn't know about it, since the pages * can be no longer dirty nor marked anymore for writeback (if a * subsequent modification to the extent buffer didn't happen before the * transaction commit), which makes filemap_fdata[write|wait]_range not * able to find the pages tagged with SetPageError at transaction * commit time. So if this happens we must abort the transaction, * otherwise we commit a super block with btree roots that point to * btree nodes/leafs whose content on disk is invalid - either garbage * or the content of some node/leaf from a past generation that got * cowed or deleted and is no longer valid. * * Note: setting AS_EIO/AS_ENOSPC in the btree inode's i_mapping would * not be enough - we need to distinguish between log tree extents vs * non-log tree extents, and the next filemap_fdatawait_range() call * will catch and clear such errors in the mapping - and that call might * be from a log sync and not from a transaction commit. Also, checking * for the eb flag EXTENT_BUFFER_WRITE_ERR at transaction commit time is * not done and would not be reliable - the eb might have been released * from memory and reading it back again means that flag would not be * set (since it's a runtime flag, not persisted on disk). * * Using the flags below in the btree inode also makes us achieve the * goal of AS_EIO/AS_ENOSPC when writepages() returns success, started * writeback for all dirty pages and before filemap_fdatawait_range() * is called, the writeback for all dirty pages had already finished * with errors - because we were not using AS_EIO/AS_ENOSPC, * filemap_fdatawait_range() would return success, as it could not know * that writeback errors happened (the pages were no longer tagged for * writeback). */ switch (eb->log_index) { case -1: set_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags); break; case 0: set_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags); break; case 1: set_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags); break; default: BUG(); /* unexpected, logic error */ } } /* * The endio specific version which won't touch any unsafe spinlock in endio * context. */ static struct extent_buffer *find_extent_buffer_nolock( struct btrfs_fs_info *fs_info, u64 start) { struct extent_buffer *eb; rcu_read_lock(); eb = radix_tree_lookup(&fs_info->buffer_radix, start >> fs_info->sectorsize_bits); if (eb && atomic_inc_not_zero(&eb->refs)) { rcu_read_unlock(); return eb; } rcu_read_unlock(); return NULL; } static void end_bbio_meta_write(struct btrfs_bio *bbio) { struct extent_buffer *eb = bbio->private; struct btrfs_fs_info *fs_info = eb->fs_info; bool uptodate = !bbio->bio.bi_status; struct folio_iter fi; u32 bio_offset = 0; if (!uptodate) set_btree_ioerr(eb); bio_for_each_folio_all(fi, &bbio->bio) { u64 start = eb->start + bio_offset; struct folio *folio = fi.folio; u32 len = fi.length; btrfs_folio_clear_writeback(fs_info, folio, start, len); bio_offset += len; } clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags); smp_mb__after_atomic(); wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK); bio_put(&bbio->bio); } static void prepare_eb_write(struct extent_buffer *eb) { u32 nritems; unsigned long start; unsigned long end; clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags); /* Set btree blocks beyond nritems with 0 to avoid stale content */ nritems = btrfs_header_nritems(eb); if (btrfs_header_level(eb) > 0) { end = btrfs_node_key_ptr_offset(eb, nritems); memzero_extent_buffer(eb, end, eb->len - end); } else { /* * Leaf: * header 0 1 2 .. N ... data_N .. data_2 data_1 data_0 */ start = btrfs_item_nr_offset(eb, nritems); end = btrfs_item_nr_offset(eb, 0); if (nritems == 0) end += BTRFS_LEAF_DATA_SIZE(eb->fs_info); else end += btrfs_item_offset(eb, nritems - 1); memzero_extent_buffer(eb, start, end - start); } } static noinline_for_stack void write_one_eb(struct extent_buffer *eb, struct writeback_control *wbc) { struct btrfs_fs_info *fs_info = eb->fs_info; struct btrfs_bio *bbio; prepare_eb_write(eb); bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES, REQ_OP_WRITE | REQ_META | wbc_to_write_flags(wbc), eb->fs_info, end_bbio_meta_write, eb); bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT; bio_set_dev(&bbio->bio, fs_info->fs_devices->latest_dev->bdev); wbc_init_bio(wbc, &bbio->bio); bbio->inode = BTRFS_I(eb->fs_info->btree_inode); bbio->file_offset = eb->start; if (fs_info->nodesize < PAGE_SIZE) { struct folio *folio = eb->folios[0]; bool ret; folio_lock(folio); btrfs_subpage_set_writeback(fs_info, folio, eb->start, eb->len); if (btrfs_subpage_clear_and_test_dirty(fs_info, folio, eb->start, eb->len)) { folio_clear_dirty_for_io(folio); wbc->nr_to_write--; } ret = bio_add_folio(&bbio->bio, folio, eb->len, eb->start - folio_pos(folio)); ASSERT(ret); wbc_account_cgroup_owner(wbc, folio_page(folio, 0), eb->len); folio_unlock(folio); } else { int num_folios = num_extent_folios(eb); for (int i = 0; i < num_folios; i++) { struct folio *folio = eb->folios[i]; bool ret; folio_lock(folio); folio_clear_dirty_for_io(folio); folio_start_writeback(folio); ret = bio_add_folio(&bbio->bio, folio, eb->folio_size, 0); ASSERT(ret); wbc_account_cgroup_owner(wbc, folio_page(folio, 0), eb->folio_size); wbc->nr_to_write -= folio_nr_pages(folio); folio_unlock(folio); } } btrfs_submit_bio(bbio, 0); } /* * Submit one subpage btree page. * * The main difference to submit_eb_page() is: * - Page locking * For subpage, we don't rely on page locking at all. * * - Flush write bio * We only flush bio if we may be unable to fit current extent buffers into * current bio. * * Return >=0 for the number of submitted extent buffers. * Return <0 for fatal error. */ static int submit_eb_subpage(struct page *page, struct writeback_control *wbc) { struct btrfs_fs_info *fs_info = page_to_fs_info(page); struct folio *folio = page_folio(page); int submitted = 0; u64 page_start = page_offset(page); int bit_start = 0; int sectors_per_node = fs_info->nodesize >> fs_info->sectorsize_bits; /* Lock and write each dirty extent buffers in the range */ while (bit_start < fs_info->subpage_info->bitmap_nr_bits) { struct btrfs_subpage *subpage = folio_get_private(folio); struct extent_buffer *eb; unsigned long flags; u64 start; /* * Take private lock to ensure the subpage won't be detached * in the meantime. */ spin_lock(&page->mapping->i_private_lock); if (!folio_test_private(folio)) { spin_unlock(&page->mapping->i_private_lock); break; } spin_lock_irqsave(&subpage->lock, flags); if (!test_bit(bit_start + fs_info->subpage_info->dirty_offset, subpage->bitmaps)) { spin_unlock_irqrestore(&subpage->lock, flags); spin_unlock(&page->mapping->i_private_lock); bit_start++; continue; } start = page_start + bit_start * fs_info->sectorsize; bit_start += sectors_per_node; /* * Here we just want to grab the eb without touching extra * spin locks, so call find_extent_buffer_nolock(). */ eb = find_extent_buffer_nolock(fs_info, start); spin_unlock_irqrestore(&subpage->lock, flags); spin_unlock(&page->mapping->i_private_lock); /* * The eb has already reached 0 refs thus find_extent_buffer() * doesn't return it. We don't need to write back such eb * anyway. */ if (!eb) continue; if (lock_extent_buffer_for_io(eb, wbc)) { write_one_eb(eb, wbc); submitted++; } free_extent_buffer(eb); } return submitted; } /* * Submit all page(s) of one extent buffer. * * @page: the page of one extent buffer * @eb_context: to determine if we need to submit this page, if current page * belongs to this eb, we don't need to submit * * The caller should pass each page in their bytenr order, and here we use * @eb_context to determine if we have submitted pages of one extent buffer. * * If we have, we just skip until we hit a new page that doesn't belong to * current @eb_context. * * If not, we submit all the page(s) of the extent buffer. * * Return >0 if we have submitted the extent buffer successfully. * Return 0 if we don't need to submit the page, as it's already submitted by * previous call. * Return <0 for fatal error. */ static int submit_eb_page(struct page *page, struct btrfs_eb_write_context *ctx) { struct writeback_control *wbc = ctx->wbc; struct address_space *mapping = page->mapping; struct folio *folio = page_folio(page); struct extent_buffer *eb; int ret; if (!folio_test_private(folio)) return 0; if (page_to_fs_info(page)->nodesize < PAGE_SIZE) return submit_eb_subpage(page, wbc); spin_lock(&mapping->i_private_lock); if (!folio_test_private(folio)) { spin_unlock(&mapping->i_private_lock); return 0; } eb = folio_get_private(folio); /* * Shouldn't happen and normally this would be a BUG_ON but no point * crashing the machine for something we can survive anyway. */ if (WARN_ON(!eb)) { spin_unlock(&mapping->i_private_lock); return 0; } if (eb == ctx->eb) { spin_unlock(&mapping->i_private_lock); return 0; } ret = atomic_inc_not_zero(&eb->refs); spin_unlock(&mapping->i_private_lock); if (!ret) return 0; ctx->eb = eb; ret = btrfs_check_meta_write_pointer(eb->fs_info, ctx); if (ret) { if (ret == -EBUSY) ret = 0; free_extent_buffer(eb); return ret; } if (!lock_extent_buffer_for_io(eb, wbc)) { free_extent_buffer(eb); return 0; } /* Implies write in zoned mode. */ if (ctx->zoned_bg) { /* Mark the last eb in the block group. */ btrfs_schedule_zone_finish_bg(ctx->zoned_bg, eb); ctx->zoned_bg->meta_write_pointer += eb->len; } write_one_eb(eb, wbc); free_extent_buffer(eb); return 1; } int btree_write_cache_pages(struct address_space *mapping, struct writeback_control *wbc) { struct btrfs_eb_write_context ctx = { .wbc = wbc }; struct btrfs_fs_info *fs_info = inode_to_fs_info(mapping->host); int ret = 0; int done = 0; int nr_to_write_done = 0; struct folio_batch fbatch; unsigned int nr_folios; pgoff_t index; pgoff_t end; /* Inclusive */ int scanned = 0; xa_mark_t tag; folio_batch_init(&fbatch); if (wbc->range_cyclic) { index = mapping->writeback_index; /* Start from prev offset */ end = -1; /* * Start from the beginning does not need to cycle over the * range, mark it as scanned. */ scanned = (index == 0); } else { index = wbc->range_start >> PAGE_SHIFT; end = wbc->range_end >> PAGE_SHIFT; scanned = 1; } if (wbc->sync_mode == WB_SYNC_ALL) tag = PAGECACHE_TAG_TOWRITE; else tag = PAGECACHE_TAG_DIRTY; btrfs_zoned_meta_io_lock(fs_info); retry: if (wbc->sync_mode == WB_SYNC_ALL) tag_pages_for_writeback(mapping, index, end); while (!done && !nr_to_write_done && (index <= end) && (nr_folios = filemap_get_folios_tag(mapping, &index, end, tag, &fbatch))) { unsigned i; for (i = 0; i < nr_folios; i++) { struct folio *folio = fbatch.folios[i]; ret = submit_eb_page(&folio->page, &ctx); if (ret == 0) continue; if (ret < 0) { done = 1; break; } /* * the filesystem may choose to bump up nr_to_write. * We have to make sure to honor the new nr_to_write * at any time */ nr_to_write_done = wbc->nr_to_write <= 0; } folio_batch_release(&fbatch); cond_resched(); } if (!scanned && !done) { /* * We hit the last page and there is more work to be done: wrap * back to the start of the file */ scanned = 1; index = 0; goto retry; } /* * If something went wrong, don't allow any metadata write bio to be * submitted. * * This would prevent use-after-free if we had dirty pages not * cleaned up, which can still happen by fuzzed images. * * - Bad extent tree * Allowing existing tree block to be allocated for other trees. * * - Log tree operations * Exiting tree blocks get allocated to log tree, bumps its * generation, then get cleaned in tree re-balance. * Such tree block will not be written back, since it's clean, * thus no WRITTEN flag set. * And after log writes back, this tree block is not traced by * any dirty extent_io_tree. * * - Offending tree block gets re-dirtied from its original owner * Since it has bumped generation, no WRITTEN flag, it can be * reused without COWing. This tree block will not be traced * by btrfs_transaction::dirty_pages. * * Now such dirty tree block will not be cleaned by any dirty * extent io tree. Thus we don't want to submit such wild eb * if the fs already has error. * * We can get ret > 0 from submit_extent_page() indicating how many ebs * were submitted. Reset it to 0 to avoid false alerts for the caller. */ if (ret > 0) ret = 0; if (!ret && BTRFS_FS_ERROR(fs_info)) ret = -EROFS; if (ctx.zoned_bg) btrfs_put_block_group(ctx.zoned_bg); btrfs_zoned_meta_io_unlock(fs_info); return ret; } /* * Walk the list of dirty pages of the given address space and write all of them. * * @mapping: address space structure to write * @wbc: subtract the number of written pages from *@wbc->nr_to_write * @bio_ctrl: holds context for the write, namely the bio * * If a page is already under I/O, write_cache_pages() skips it, even * if it's dirty. This is desirable behaviour for memory-cleaning writeback, * but it is INCORRECT for data-integrity system calls such as fsync(). fsync() * and msync() need to guarantee that all the data which was dirty at the time * the call was made get new I/O started against them. If wbc->sync_mode is * WB_SYNC_ALL then we were called for data integrity and we must wait for * existing IO to complete. */ static int extent_write_cache_pages(struct address_space *mapping, struct btrfs_bio_ctrl *bio_ctrl) { struct writeback_control *wbc = bio_ctrl->wbc; struct inode *inode = mapping->host; int ret = 0; int done = 0; int nr_to_write_done = 0; struct folio_batch fbatch; unsigned int nr_folios; pgoff_t index; pgoff_t end; /* Inclusive */ pgoff_t done_index; int range_whole = 0; int scanned = 0; xa_mark_t tag; /* * We have to hold onto the inode so that ordered extents can do their * work when the IO finishes. The alternative to this is failing to add * an ordered extent if the igrab() fails there and that is a huge pain * to deal with, so instead just hold onto the inode throughout the * writepages operation. If it fails here we are freeing up the inode * anyway and we'd rather not waste our time writing out stuff that is * going to be truncated anyway. */ if (!igrab(inode)) return 0; folio_batch_init(&fbatch); if (wbc->range_cyclic) { index = mapping->writeback_index; /* Start from prev offset */ end = -1; /* * Start from the beginning does not need to cycle over the * range, mark it as scanned. */ scanned = (index == 0); } else { index = wbc->range_start >> PAGE_SHIFT; end = wbc->range_end >> PAGE_SHIFT; if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) range_whole = 1; scanned = 1; } /* * We do the tagged writepage as long as the snapshot flush bit is set * and we are the first one who do the filemap_flush() on this inode. * * The nr_to_write == LONG_MAX is needed to make sure other flushers do * not race in and drop the bit. */ if (range_whole && wbc->nr_to_write == LONG_MAX && test_and_clear_bit(BTRFS_INODE_SNAPSHOT_FLUSH, &BTRFS_I(inode)->runtime_flags)) wbc->tagged_writepages = 1; if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) tag = PAGECACHE_TAG_TOWRITE; else tag = PAGECACHE_TAG_DIRTY; retry: if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) tag_pages_for_writeback(mapping, index, end); done_index = index; while (!done && !nr_to_write_done && (index <= end) && (nr_folios = filemap_get_folios_tag(mapping, &index, end, tag, &fbatch))) { unsigned i; for (i = 0; i < nr_folios; i++) { struct folio *folio = fbatch.folios[i]; done_index = folio_next_index(folio); /* * At this point we hold neither the i_pages lock nor * the page lock: the page may be truncated or * invalidated (changing page->mapping to NULL), * or even swizzled back from swapper_space to * tmpfs file mapping */ if (!folio_trylock(folio)) { submit_write_bio(bio_ctrl, 0); folio_lock(folio); } if (unlikely(folio->mapping != mapping)) { folio_unlock(folio); continue; } if (!folio_test_dirty(folio)) { /* Someone wrote it for us. */ folio_unlock(folio); continue; } if (wbc->sync_mode != WB_SYNC_NONE) { if (folio_test_writeback(folio)) submit_write_bio(bio_ctrl, 0); folio_wait_writeback(folio); } if (folio_test_writeback(folio) || !folio_clear_dirty_for_io(folio)) { folio_unlock(folio); continue; } ret = __extent_writepage(&folio->page, bio_ctrl); if (ret < 0) { done = 1; break; } /* * The filesystem may choose to bump up nr_to_write. * We have to make sure to honor the new nr_to_write * at any time. */ nr_to_write_done = (wbc->sync_mode == WB_SYNC_NONE && wbc->nr_to_write <= 0); } folio_batch_release(&fbatch); cond_resched(); } if (!scanned && !done) { /* * We hit the last page and there is more work to be done: wrap * back to the start of the file */ scanned = 1; index = 0; /* * If we're looping we could run into a page that is locked by a * writer and that writer could be waiting on writeback for a * page in our current bio, and thus deadlock, so flush the * write bio here. */ submit_write_bio(bio_ctrl, 0); goto retry; } if (wbc->range_cyclic || (wbc->nr_to_write > 0 && range_whole)) mapping->writeback_index = done_index; btrfs_add_delayed_iput(BTRFS_I(inode)); return ret; } /* * Submit the pages in the range to bio for call sites which delalloc range has * already been ran (aka, ordered extent inserted) and all pages are still * locked. */ void extent_write_locked_range(struct inode *inode, struct page *locked_page, u64 start, u64 end, struct writeback_control *wbc, bool pages_dirty) { bool found_error = false; int ret = 0; struct address_space *mapping = inode->i_mapping; struct btrfs_fs_info *fs_info = inode_to_fs_info(inode); const u32 sectorsize = fs_info->sectorsize; loff_t i_size = i_size_read(inode); u64 cur = start; struct btrfs_bio_ctrl bio_ctrl = { .wbc = wbc, .opf = REQ_OP_WRITE | wbc_to_write_flags(wbc), }; if (wbc->no_cgroup_owner) bio_ctrl.opf |= REQ_BTRFS_CGROUP_PUNT; ASSERT(IS_ALIGNED(start, sectorsize) && IS_ALIGNED(end + 1, sectorsize)); while (cur <= end) { u64 cur_end = min(round_down(cur, PAGE_SIZE) + PAGE_SIZE - 1, end); u32 cur_len = cur_end + 1 - cur; struct page *page; int nr = 0; page = find_get_page(mapping, cur >> PAGE_SHIFT); ASSERT(PageLocked(page)); if (pages_dirty && page != locked_page) { ASSERT(PageDirty(page)); clear_page_dirty_for_io(page); } ret = __extent_writepage_io(BTRFS_I(inode), page, &bio_ctrl, i_size, &nr); if (ret == 1) goto next_page; /* Make sure the mapping tag for page dirty gets cleared. */ if (nr == 0) { set_page_writeback(page); end_page_writeback(page); } if (ret) { btrfs_mark_ordered_io_finished(BTRFS_I(inode), page, cur, cur_len, !ret); mapping_set_error(page->mapping, ret); } btrfs_folio_unlock_writer(fs_info, page_folio(page), cur, cur_len); if (ret < 0) found_error = true; next_page: put_page(page); cur = cur_end + 1; } submit_write_bio(&bio_ctrl, found_error ? ret : 0); } int extent_writepages(struct address_space *mapping, struct writeback_control *wbc) { struct inode *inode = mapping->host; int ret = 0; struct btrfs_bio_ctrl bio_ctrl = { .wbc = wbc, .opf = REQ_OP_WRITE | wbc_to_write_flags(wbc), }; /* * Allow only a single thread to do the reloc work in zoned mode to * protect the write pointer updates. */ btrfs_zoned_data_reloc_lock(BTRFS_I(inode)); ret = extent_write_cache_pages(mapping, &bio_ctrl); submit_write_bio(&bio_ctrl, ret); btrfs_zoned_data_reloc_unlock(BTRFS_I(inode)); return ret; } void extent_readahead(struct readahead_control *rac) { struct btrfs_bio_ctrl bio_ctrl = { .opf = REQ_OP_READ | REQ_RAHEAD }; struct page *pagepool[16]; struct extent_map *em_cached = NULL; u64 prev_em_start = (u64)-1; int nr; while ((nr = readahead_page_batch(rac, pagepool))) { u64 contig_start = readahead_pos(rac); u64 contig_end = contig_start + readahead_batch_length(rac) - 1; contiguous_readpages(pagepool, nr, contig_start, contig_end, &em_cached, &bio_ctrl, &prev_em_start); } if (em_cached) free_extent_map(em_cached); submit_one_bio(&bio_ctrl); } /* * basic invalidate_folio code, this waits on any locked or writeback * ranges corresponding to the folio, and then deletes any extent state * records from the tree */ int extent_invalidate_folio(struct extent_io_tree *tree, struct folio *folio, size_t offset) { struct extent_state *cached_state = NULL; u64 start = folio_pos(folio); u64 end = start + folio_size(folio) - 1; size_t blocksize = folio_to_fs_info(folio)->sectorsize; /* This function is only called for the btree inode */ ASSERT(tree->owner == IO_TREE_BTREE_INODE_IO); start += ALIGN(offset, blocksize); if (start > end) return 0; lock_extent(tree, start, end, &cached_state); folio_wait_writeback(folio); /* * Currently for btree io tree, only EXTENT_LOCKED is utilized, * so here we only need to unlock the extent range to free any * existing extent state. */ unlock_extent(tree, start, end, &cached_state); return 0; } /* * a helper for release_folio, this tests for areas of the page that * are locked or under IO and drops the related state bits if it is safe * to drop the page. */ static int try_release_extent_state(struct extent_io_tree *tree, struct page *page, gfp_t mask) { u64 start = page_offset(page); u64 end = start + PAGE_SIZE - 1; int ret = 1; if (test_range_bit_exists(tree, start, end, EXTENT_LOCKED)) { ret = 0; } else { u32 clear_bits = ~(EXTENT_LOCKED | EXTENT_NODATASUM | EXTENT_DELALLOC_NEW | EXTENT_CTLBITS | EXTENT_QGROUP_RESERVED); /* * At this point we can safely clear everything except the * locked bit, the nodatasum bit and the delalloc new bit. * The delalloc new bit will be cleared by ordered extent * completion. */ ret = __clear_extent_bit(tree, start, end, clear_bits, NULL, NULL); /* if clear_extent_bit failed for enomem reasons, * we can't allow the release to continue. */ if (ret < 0) ret = 0; else ret = 1; } return ret; } /* * a helper for release_folio. As long as there are no locked extents * in the range corresponding to the page, both state records and extent * map records are removed */ int try_release_extent_mapping(struct page *page, gfp_t mask) { struct extent_map *em; u64 start = page_offset(page); u64 end = start + PAGE_SIZE - 1; struct btrfs_inode *btrfs_inode = page_to_inode(page); struct extent_io_tree *tree = &btrfs_inode->io_tree; struct extent_map_tree *map = &btrfs_inode->extent_tree; if (gfpflags_allow_blocking(mask) && page->mapping->host->i_size > SZ_16M) { u64 len; while (start <= end) { struct btrfs_fs_info *fs_info; u64 cur_gen; len = end - start + 1; write_lock(&map->lock); em = lookup_extent_mapping(map, start, len); if (!em) { write_unlock(&map->lock); break; } if ((em->flags & EXTENT_FLAG_PINNED) || em->start != start) { write_unlock(&map->lock); free_extent_map(em); break; } if (test_range_bit_exists(tree, em->start, extent_map_end(em) - 1, EXTENT_LOCKED)) goto next; /* * If it's not in the list of modified extents, used * by a fast fsync, we can remove it. If it's being * logged we can safely remove it since fsync took an * extra reference on the em. */ if (list_empty(&em->list) || (em->flags & EXTENT_FLAG_LOGGING)) goto remove_em; /* * If it's in the list of modified extents, remove it * only if its generation is older then the current one, * in which case we don't need it for a fast fsync. * Otherwise don't remove it, we could be racing with an * ongoing fast fsync that could miss the new extent. */ fs_info = btrfs_inode->root->fs_info; spin_lock(&fs_info->trans_lock); cur_gen = fs_info->generation; spin_unlock(&fs_info->trans_lock); if (em->generation >= cur_gen) goto next; remove_em: /* * We only remove extent maps that are not in the list of * modified extents or that are in the list but with a * generation lower then the current generation, so there * is no need to set the full fsync flag on the inode (it * hurts the fsync performance for workloads with a data * size that exceeds or is close to the system's memory). */ remove_extent_mapping(map, em); /* once for the rb tree */ free_extent_map(em); next: start = extent_map_end(em); write_unlock(&map->lock); /* once for us */ free_extent_map(em); cond_resched(); /* Allow large-extent preemption. */ } } return try_release_extent_state(tree, page, mask); } struct btrfs_fiemap_entry { u64 offset; u64 phys; u64 len; u32 flags; }; /* * Indicate the caller of emit_fiemap_extent() that it needs to unlock the file * range from the inode's io tree, unlock the subvolume tree search path, flush * the fiemap cache and relock the file range and research the subvolume tree. * The value here is something negative that can't be confused with a valid * errno value and different from 1 because that's also a return value from * fiemap_fill_next_extent() and also it's often used to mean some btree search * did not find a key, so make it some distinct negative value. */ #define BTRFS_FIEMAP_FLUSH_CACHE (-(MAX_ERRNO + 1)) /* * Used to: * * - Cache the next entry to be emitted to the fiemap buffer, so that we can * merge extents that are contiguous and can be grouped as a single one; * * - Store extents ready to be written to the fiemap buffer in an intermediary * buffer. This intermediary buffer is to ensure that in case the fiemap * buffer is memory mapped to the fiemap target file, we don't deadlock * during btrfs_page_mkwrite(). This is because during fiemap we are locking * an extent range in order to prevent races with delalloc flushing and * ordered extent completion, which is needed in order to reliably detect * delalloc in holes and prealloc extents. And this can lead to a deadlock * if the fiemap buffer is memory mapped to the file we are running fiemap * against (a silly, useless in practice scenario, but possible) because * btrfs_page_mkwrite() will try to lock the same extent range. */ struct fiemap_cache { /* An array of ready fiemap entries. */ struct btrfs_fiemap_entry *entries; /* Number of entries in the entries array. */ int entries_size; /* Index of the next entry in the entries array to write to. */ int entries_pos; /* * Once the entries array is full, this indicates what's the offset for * the next file extent item we must search for in the inode's subvolume * tree after unlocking the extent range in the inode's io tree and * releasing the search path. */ u64 next_search_offset; /* * This matches struct fiemap_extent_info::fi_mapped_extents, we use it * to count ourselves emitted extents and stop instead of relying on * fiemap_fill_next_extent() because we buffer ready fiemap entries at * the @entries array, and we want to stop as soon as we hit the max * amount of extents to map, not just to save time but also to make the * logic at extent_fiemap() simpler. */ unsigned int extents_mapped; /* Fields for the cached extent (unsubmitted, not ready, extent). */ u64 offset; u64 phys; u64 len; u32 flags; bool cached; }; static int flush_fiemap_cache(struct fiemap_extent_info *fieinfo, struct fiemap_cache *cache) { for (int i = 0; i < cache->entries_pos; i++) { struct btrfs_fiemap_entry *entry = &cache->entries[i]; int ret; ret = fiemap_fill_next_extent(fieinfo, entry->offset, entry->phys, entry->len, entry->flags); /* * Ignore 1 (reached max entries) because we keep track of that * ourselves in emit_fiemap_extent(). */ if (ret < 0) return ret; } cache->entries_pos = 0; return 0; } /* * Helper to submit fiemap extent. * * Will try to merge current fiemap extent specified by @offset, @phys, * @len and @flags with cached one. * And only when we fails to merge, cached one will be submitted as * fiemap extent. * * Return value is the same as fiemap_fill_next_extent(). */ static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo, struct fiemap_cache *cache, u64 offset, u64 phys, u64 len, u32 flags) { struct btrfs_fiemap_entry *entry; u64 cache_end; /* Set at the end of extent_fiemap(). */ ASSERT((flags & FIEMAP_EXTENT_LAST) == 0); if (!cache->cached) goto assign; /* * When iterating the extents of the inode, at extent_fiemap(), we may * find an extent that starts at an offset behind the end offset of the * previous extent we processed. This happens if fiemap is called * without FIEMAP_FLAG_SYNC and there are ordered extents completing * after we had to unlock the file range, release the search path, emit * the fiemap extents stored in the buffer (cache->entries array) and * the lock the remainder of the range and re-search the btree. * * For example we are in leaf X processing its last item, which is the * file extent item for file range [512K, 1M[, and after * btrfs_next_leaf() releases the path, there's an ordered extent that * completes for the file range [768K, 2M[, and that results in trimming * the file extent item so that it now corresponds to the file range * [512K, 768K[ and a new file extent item is inserted for the file * range [768K, 2M[, which may end up as the last item of leaf X or as * the first item of the next leaf - in either case btrfs_next_leaf() * will leave us with a path pointing to the new extent item, for the * file range [768K, 2M[, since that's the first key that follows the * last one we processed. So in order not to report overlapping extents * to user space, we trim the length of the previously cached extent and * emit it. * * Upon calling btrfs_next_leaf() we may also find an extent with an * offset smaller than or equals to cache->offset, and this happens * when we had a hole or prealloc extent with several delalloc ranges in * it, but after btrfs_next_leaf() released the path, delalloc was * flushed and the resulting ordered extents were completed, so we can * now have found a file extent item for an offset that is smaller than * or equals to what we have in cache->offset. We deal with this as * described below. */ cache_end = cache->offset + cache->len; if (cache_end > offset) { if (offset == cache->offset) { /* * We cached a dealloc range (found in the io tree) for * a hole or prealloc extent and we have now found a * file extent item for the same offset. What we have * now is more recent and up to date, so discard what * we had in the cache and use what we have just found. */ goto assign; } else if (offset > cache->offset) { /* * The extent range we previously found ends after the * offset of the file extent item we found and that * offset falls somewhere in the middle of that previous * extent range. So adjust the range we previously found * to end at the offset of the file extent item we have * just found, since this extent is more up to date. * Emit that adjusted range and cache the file extent * item we have just found. This corresponds to the case * where a previously found file extent item was split * due to an ordered extent completing. */ cache->len = offset - cache->offset; goto emit; } else { const u64 range_end = offset + len; /* * The offset of the file extent item we have just found * is behind the cached offset. This means we were * processing a hole or prealloc extent for which we * have found delalloc ranges (in the io tree), so what * we have in the cache is the last delalloc range we * found while the file extent item we found can be * either for a whole delalloc range we previously * emmitted or only a part of that range. * * We have two cases here: * * 1) The file extent item's range ends at or behind the * cached extent's end. In this case just ignore the * current file extent item because we don't want to * overlap with previous ranges that may have been * emmitted already; * * 2) The file extent item starts behind the currently * cached extent but its end offset goes beyond the * end offset of the cached extent. We don't want to * overlap with a previous range that may have been * emmitted already, so we emit the currently cached * extent and then partially store the current file * extent item's range in the cache, for the subrange * going the cached extent's end to the end of the * file extent item. */ if (range_end <= cache_end) return 0; if (!(flags & (FIEMAP_EXTENT_ENCODED | FIEMAP_EXTENT_DELALLOC))) phys += cache_end - offset; offset = cache_end; len = range_end - cache_end; goto emit; } } /* * Only merges fiemap extents if * 1) Their logical addresses are continuous * * 2) Their physical addresses are continuous * So truly compressed (physical size smaller than logical size) * extents won't get merged with each other * * 3) Share same flags */ if (cache->offset + cache->len == offset && cache->phys + cache->len == phys && cache->flags == flags) { cache->len += len; return 0; } emit: /* Not mergeable, need to submit cached one */ if (cache->entries_pos == cache->entries_size) { /* * We will need to research for the end offset of the last * stored extent and not from the current offset, because after * unlocking the range and releasing the path, if there's a hole * between that end offset and this current offset, a new extent * may have been inserted due to a new write, so we don't want * to miss it. */ entry = &cache->entries[cache->entries_size - 1]; cache->next_search_offset = entry->offset + entry->len; cache->cached = false; return BTRFS_FIEMAP_FLUSH_CACHE; } entry = &cache->entries[cache->entries_pos]; entry->offset = cache->offset; entry->phys = cache->phys; entry->len = cache->len; entry->flags = cache->flags; cache->entries_pos++; cache->extents_mapped++; if (cache->extents_mapped == fieinfo->fi_extents_max) { cache->cached = false; return 1; } assign: cache->cached = true; cache->offset = offset; cache->phys = phys; cache->len = len; cache->flags = flags; return 0; } /* * Emit last fiemap cache * * The last fiemap cache may still be cached in the following case: * 0 4k 8k * |<- Fiemap range ->| * |<------------ First extent ----------->| * * In this case, the first extent range will be cached but not emitted. * So we must emit it before ending extent_fiemap(). */ static int emit_last_fiemap_cache(struct fiemap_extent_info *fieinfo, struct fiemap_cache *cache) { int ret; if (!cache->cached) return 0; ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys, cache->len, cache->flags); cache->cached = false; if (ret > 0) ret = 0; return ret; } static int fiemap_next_leaf_item(struct btrfs_inode *inode, struct btrfs_path *path) { struct extent_buffer *clone = path->nodes[0]; struct btrfs_key key; int slot; int ret; path->slots[0]++; if (path->slots[0] < btrfs_header_nritems(path->nodes[0])) return 0; /* * Add a temporary extra ref to an already cloned extent buffer to * prevent btrfs_next_leaf() freeing it, we want to reuse it to avoid * the cost of allocating a new one. */ ASSERT(test_bit(EXTENT_BUFFER_UNMAPPED, &clone->bflags)); atomic_inc(&clone->refs); ret = btrfs_next_leaf(inode->root, path); if (ret != 0) goto out; /* * Don't bother with cloning if there are no more file extent items for * our inode. */ btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); if (key.objectid != btrfs_ino(inode) || key.type != BTRFS_EXTENT_DATA_KEY) { ret = 1; goto out; } /* See the comment at fiemap_search_slot() about why we clone. */ copy_extent_buffer_full(clone, path->nodes[0]); /* * Important to preserve the start field, for the optimizations when * checking if extents are shared (see extent_fiemap()). */ clone->start = path->nodes[0]->start; slot = path->slots[0]; btrfs_release_path(path); path->nodes[0] = clone; path->slots[0] = slot; out: if (ret) free_extent_buffer(clone); return ret; } /* * Search for the first file extent item that starts at a given file offset or * the one that starts immediately before that offset. * Returns: 0 on success, < 0 on error, 1 if not found. */ static int fiemap_search_slot(struct btrfs_inode *inode, struct btrfs_path *path, u64 file_offset) { const u64 ino = btrfs_ino(inode); struct btrfs_root *root = inode->root; struct extent_buffer *clone; struct btrfs_key key; int slot; int ret; key.objectid = ino; key.type = BTRFS_EXTENT_DATA_KEY; key.offset = file_offset; ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); if (ret < 0) return ret; if (ret > 0 && path->slots[0] > 0) { btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0] - 1); if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY) path->slots[0]--; } if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) { ret = btrfs_next_leaf(root, path); if (ret != 0) return ret; btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY) return 1; } /* * We clone the leaf and use it during fiemap. This is because while * using the leaf we do expensive things like checking if an extent is * shared, which can take a long time. In order to prevent blocking * other tasks for too long, we use a clone of the leaf. We have locked * the file range in the inode's io tree, so we know none of our file * extent items can change. This way we avoid blocking other tasks that * want to insert items for other inodes in the same leaf or b+tree * rebalance operations (triggered for example when someone is trying * to push items into this leaf when trying to insert an item in a * neighbour leaf). * We also need the private clone because holding a read lock on an * extent buffer of the subvolume's b+tree will make lockdep unhappy * when we check if extents are shared, as backref walking may need to * lock the same leaf we are processing. */ clone = btrfs_clone_extent_buffer(path->nodes[0]); if (!clone) return -ENOMEM; slot = path->slots[0]; btrfs_release_path(path); path->nodes[0] = clone; path->slots[0] = slot; return 0; } /* * Process a range which is a hole or a prealloc extent in the inode's subvolume * btree. If @disk_bytenr is 0, we are dealing with a hole, otherwise a prealloc * extent. The end offset (@end) is inclusive. */ static int fiemap_process_hole(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo, struct fiemap_cache *cache, struct extent_state **delalloc_cached_state, struct btrfs_backref_share_check_ctx *backref_ctx, u64 disk_bytenr, u64 extent_offset, u64 extent_gen, u64 start, u64 end) { const u64 i_size = i_size_read(&inode->vfs_inode); u64 cur_offset = start; u64 last_delalloc_end = 0; u32 prealloc_flags = FIEMAP_EXTENT_UNWRITTEN; bool checked_extent_shared = false; int ret; /* * There can be no delalloc past i_size, so don't waste time looking for * it beyond i_size. */ while (cur_offset < end && cur_offset < i_size) { u64 delalloc_start; u64 delalloc_end; u64 prealloc_start; u64 prealloc_len = 0; bool delalloc; delalloc = btrfs_find_delalloc_in_range(inode, cur_offset, end, delalloc_cached_state, &delalloc_start, &delalloc_end); if (!delalloc) break; /* * If this is a prealloc extent we have to report every section * of it that has no delalloc. */ if (disk_bytenr != 0) { if (last_delalloc_end == 0) { prealloc_start = start; prealloc_len = delalloc_start - start; } else { prealloc_start = last_delalloc_end + 1; prealloc_len = delalloc_start - prealloc_start; } } if (prealloc_len > 0) { if (!checked_extent_shared && fieinfo->fi_extents_max) { ret = btrfs_is_data_extent_shared(inode, disk_bytenr, extent_gen, backref_ctx); if (ret < 0) return ret; else if (ret > 0) prealloc_flags |= FIEMAP_EXTENT_SHARED; checked_extent_shared = true; } ret = emit_fiemap_extent(fieinfo, cache, prealloc_start, disk_bytenr + extent_offset, prealloc_len, prealloc_flags); if (ret) return ret; extent_offset += prealloc_len; } ret = emit_fiemap_extent(fieinfo, cache, delalloc_start, 0, delalloc_end + 1 - delalloc_start, FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN); if (ret) return ret; last_delalloc_end = delalloc_end; cur_offset = delalloc_end + 1; extent_offset += cur_offset - delalloc_start; cond_resched(); } /* * Either we found no delalloc for the whole prealloc extent or we have * a prealloc extent that spans i_size or starts at or after i_size. */ if (disk_bytenr != 0 && last_delalloc_end < end) { u64 prealloc_start; u64 prealloc_len; if (last_delalloc_end == 0) { prealloc_start = start; prealloc_len = end + 1 - start; } else { prealloc_start = last_delalloc_end + 1; prealloc_len = end + 1 - prealloc_start; } if (!checked_extent_shared && fieinfo->fi_extents_max) { ret = btrfs_is_data_extent_shared(inode, disk_bytenr, extent_gen, backref_ctx); if (ret < 0) return ret; else if (ret > 0) prealloc_flags |= FIEMAP_EXTENT_SHARED; } ret = emit_fiemap_extent(fieinfo, cache, prealloc_start, disk_bytenr + extent_offset, prealloc_len, prealloc_flags); if (ret) return ret; } return 0; } static int fiemap_find_last_extent_offset(struct btrfs_inode *inode, struct btrfs_path *path, u64 *last_extent_end_ret) { const u64 ino = btrfs_ino(inode); struct btrfs_root *root = inode->root; struct extent_buffer *leaf; struct btrfs_file_extent_item *ei; struct btrfs_key key; u64 disk_bytenr; int ret; /* * Lookup the last file extent. We're not using i_size here because * there might be preallocation past i_size. */ ret = btrfs_lookup_file_extent(NULL, root, path, ino, (u64)-1, 0); /* There can't be a file extent item at offset (u64)-1 */ ASSERT(ret != 0); if (ret < 0) return ret; /* * For a non-existing key, btrfs_search_slot() always leaves us at a * slot > 0, except if the btree is empty, which is impossible because * at least it has the inode item for this inode and all the items for * the root inode 256. */ ASSERT(path->slots[0] > 0); path->slots[0]--; leaf = path->nodes[0]; btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY) { /* No file extent items in the subvolume tree. */ *last_extent_end_ret = 0; return 0; } /* * For an inline extent, the disk_bytenr is where inline data starts at, * so first check if we have an inline extent item before checking if we * have an implicit hole (disk_bytenr == 0). */ ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); if (btrfs_file_extent_type(leaf, ei) == BTRFS_FILE_EXTENT_INLINE) { *last_extent_end_ret = btrfs_file_extent_end(path); return 0; } /* * Find the last file extent item that is not a hole (when NO_HOLES is * not enabled). This should take at most 2 iterations in the worst * case: we have one hole file extent item at slot 0 of a leaf and * another hole file extent item as the last item in the previous leaf. * This is because we merge file extent items that represent holes. */ disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei); while (disk_bytenr == 0) { ret = btrfs_previous_item(root, path, ino, BTRFS_EXTENT_DATA_KEY); if (ret < 0) { return ret; } else if (ret > 0) { /* No file extent items that are not holes. */ *last_extent_end_ret = 0; return 0; } leaf = path->nodes[0]; ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei); } *last_extent_end_ret = btrfs_file_extent_end(path); return 0; } int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo, u64 start, u64 len) { const u64 ino = btrfs_ino(inode); struct extent_state *cached_state = NULL; struct extent_state *delalloc_cached_state = NULL; struct btrfs_path *path; struct fiemap_cache cache = { 0 }; struct btrfs_backref_share_check_ctx *backref_ctx; u64 last_extent_end; u64 prev_extent_end; u64 range_start; u64 range_end; const u64 sectorsize = inode->root->fs_info->sectorsize; bool stopped = false; int ret; cache.entries_size = PAGE_SIZE / sizeof(struct btrfs_fiemap_entry); cache.entries = kmalloc_array(cache.entries_size, sizeof(struct btrfs_fiemap_entry), GFP_KERNEL); backref_ctx = btrfs_alloc_backref_share_check_ctx(); path = btrfs_alloc_path(); if (!cache.entries || !backref_ctx || !path) { ret = -ENOMEM; goto out; } restart: range_start = round_down(start, sectorsize); range_end = round_up(start + len, sectorsize); prev_extent_end = range_start; lock_extent(&inode->io_tree, range_start, range_end, &cached_state); ret = fiemap_find_last_extent_offset(inode, path, &last_extent_end); if (ret < 0) goto out_unlock; btrfs_release_path(path); path->reada = READA_FORWARD; ret = fiemap_search_slot(inode, path, range_start); if (ret < 0) { goto out_unlock; } else if (ret > 0) { /* * No file extent item found, but we may have delalloc between * the current offset and i_size. So check for that. */ ret = 0; goto check_eof_delalloc; } while (prev_extent_end < range_end) { struct extent_buffer *leaf = path->nodes[0]; struct btrfs_file_extent_item *ei; struct btrfs_key key; u64 extent_end; u64 extent_len; u64 extent_offset = 0; u64 extent_gen; u64 disk_bytenr = 0; u64 flags = 0; int extent_type; u8 compression; btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY) break; extent_end = btrfs_file_extent_end(path); /* * The first iteration can leave us at an extent item that ends * before our range's start. Move to the next item. */ if (extent_end <= range_start) goto next_item; backref_ctx->curr_leaf_bytenr = leaf->start; /* We have in implicit hole (NO_HOLES feature enabled). */ if (prev_extent_end < key.offset) { const u64 hole_end = min(key.offset, range_end) - 1; ret = fiemap_process_hole(inode, fieinfo, &cache, &delalloc_cached_state, backref_ctx, 0, 0, 0, prev_extent_end, hole_end); if (ret < 0) { goto out_unlock; } else if (ret > 0) { /* fiemap_fill_next_extent() told us to stop. */ stopped = true; break; } /* We've reached the end of the fiemap range, stop. */ if (key.offset >= range_end) { stopped = true; break; } } extent_len = extent_end - key.offset; ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); compression = btrfs_file_extent_compression(leaf, ei); extent_type = btrfs_file_extent_type(leaf, ei); extent_gen = btrfs_file_extent_generation(leaf, ei); if (extent_type != BTRFS_FILE_EXTENT_INLINE) { disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei); if (compression == BTRFS_COMPRESS_NONE) extent_offset = btrfs_file_extent_offset(leaf, ei); } if (compression != BTRFS_COMPRESS_NONE) flags |= FIEMAP_EXTENT_ENCODED; if (extent_type == BTRFS_FILE_EXTENT_INLINE) { flags |= FIEMAP_EXTENT_DATA_INLINE; flags |= FIEMAP_EXTENT_NOT_ALIGNED; ret = emit_fiemap_extent(fieinfo, &cache, key.offset, 0, extent_len, flags); } else if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) { ret = fiemap_process_hole(inode, fieinfo, &cache, &delalloc_cached_state, backref_ctx, disk_bytenr, extent_offset, extent_gen, key.offset, extent_end - 1); } else if (disk_bytenr == 0) { /* We have an explicit hole. */ ret = fiemap_process_hole(inode, fieinfo, &cache, &delalloc_cached_state, backref_ctx, 0, 0, 0, key.offset, extent_end - 1); } else { /* We have a regular extent. */ if (fieinfo->fi_extents_max) { ret = btrfs_is_data_extent_shared(inode, disk_bytenr, extent_gen, backref_ctx); if (ret < 0) goto out_unlock; else if (ret > 0) flags |= FIEMAP_EXTENT_SHARED; } ret = emit_fiemap_extent(fieinfo, &cache, key.offset, disk_bytenr + extent_offset, extent_len, flags); } if (ret < 0) { goto out_unlock; } else if (ret > 0) { /* emit_fiemap_extent() told us to stop. */ stopped = true; break; } prev_extent_end = extent_end; next_item: if (fatal_signal_pending(current)) { ret = -EINTR; goto out_unlock; } ret = fiemap_next_leaf_item(inode, path); if (ret < 0) { goto out_unlock; } else if (ret > 0) { /* No more file extent items for this inode. */ break; } cond_resched(); } check_eof_delalloc: if (!stopped && prev_extent_end < range_end) { ret = fiemap_process_hole(inode, fieinfo, &cache, &delalloc_cached_state, backref_ctx, 0, 0, 0, prev_extent_end, range_end - 1); if (ret < 0) goto out_unlock; prev_extent_end = range_end; } if (cache.cached && cache.offset + cache.len >= last_extent_end) { const u64 i_size = i_size_read(&inode->vfs_inode); if (prev_extent_end < i_size) { u64 delalloc_start; u64 delalloc_end; bool delalloc; delalloc = btrfs_find_delalloc_in_range(inode, prev_extent_end, i_size - 1, &delalloc_cached_state, &delalloc_start, &delalloc_end); if (!delalloc) cache.flags |= FIEMAP_EXTENT_LAST; } else { cache.flags |= FIEMAP_EXTENT_LAST; } } out_unlock: unlock_extent(&inode->io_tree, range_start, range_end, &cached_state); if (ret == BTRFS_FIEMAP_FLUSH_CACHE) { btrfs_release_path(path); ret = flush_fiemap_cache(fieinfo, &cache); if (ret) goto out; len -= cache.next_search_offset - start; start = cache.next_search_offset; goto restart; } else if (ret < 0) { goto out; } /* * Must free the path before emitting to the fiemap buffer because we * may have a non-cloned leaf and if the fiemap buffer is memory mapped * to a file, a write into it (through btrfs_page_mkwrite()) may trigger * waiting for an ordered extent that in order to complete needs to * modify that leaf, therefore leading to a deadlock. */ btrfs_free_path(path); path = NULL; ret = flush_fiemap_cache(fieinfo, &cache); if (ret) goto out; ret = emit_last_fiemap_cache(fieinfo, &cache); out: free_extent_state(delalloc_cached_state); kfree(cache.entries); btrfs_free_backref_share_ctx(backref_ctx); btrfs_free_path(path); return ret; } static void __free_extent_buffer(struct extent_buffer *eb) { kmem_cache_free(extent_buffer_cache, eb); } static int extent_buffer_under_io(const struct extent_buffer *eb) { return (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) || test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)); } static bool folio_range_has_eb(struct btrfs_fs_info *fs_info, struct folio *folio) { struct btrfs_subpage *subpage; lockdep_assert_held(&folio->mapping->i_private_lock); if (folio_test_private(folio)) { subpage = folio_get_private(folio); if (atomic_read(&subpage->eb_refs)) return true; /* * Even there is no eb refs here, we may still have * end_page_read() call relying on page::private. */ if (atomic_read(&subpage->readers)) return true; } return false; } static void detach_extent_buffer_folio(struct extent_buffer *eb, struct folio *folio) { struct btrfs_fs_info *fs_info = eb->fs_info; const bool mapped = !test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags); /* * For mapped eb, we're going to change the folio private, which should * be done under the i_private_lock. */ if (mapped) spin_lock(&folio->mapping->i_private_lock); if (!folio_test_private(folio)) { if (mapped) spin_unlock(&folio->mapping->i_private_lock); return; } if (fs_info->nodesize >= PAGE_SIZE) { /* * We do this since we'll remove the pages after we've * removed the eb from the radix tree, so we could race * and have this page now attached to the new eb. So * only clear folio if it's still connected to * this eb. */ if (folio_test_private(folio) && folio_get_private(folio) == eb) { BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)); BUG_ON(folio_test_dirty(folio)); BUG_ON(folio_test_writeback(folio)); /* We need to make sure we haven't be attached to a new eb. */ folio_detach_private(folio); } if (mapped) spin_unlock(&folio->mapping->i_private_lock); return; } /* * For subpage, we can have dummy eb with folio private attached. In * this case, we can directly detach the private as such folio is only * attached to one dummy eb, no sharing. */ if (!mapped) { btrfs_detach_subpage(fs_info, folio); return; } btrfs_folio_dec_eb_refs(fs_info, folio); /* * We can only detach the folio private if there are no other ebs in the * page range and no unfinished IO. */ if (!folio_range_has_eb(fs_info, folio)) btrfs_detach_subpage(fs_info, folio); spin_unlock(&folio->mapping->i_private_lock); } /* Release all pages attached to the extent buffer */ static void btrfs_release_extent_buffer_pages(struct extent_buffer *eb) { ASSERT(!extent_buffer_under_io(eb)); for (int i = 0; i < INLINE_EXTENT_BUFFER_PAGES; i++) { struct folio *folio = eb->folios[i]; if (!folio) continue; detach_extent_buffer_folio(eb, folio); /* One for when we allocated the folio. */ folio_put(folio); } } /* * Helper for releasing the extent buffer. */ static inline void btrfs_release_extent_buffer(struct extent_buffer *eb) { btrfs_release_extent_buffer_pages(eb); btrfs_leak_debug_del_eb(eb); __free_extent_buffer(eb); } static struct extent_buffer * __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start, unsigned long len) { struct extent_buffer *eb = NULL; eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|__GFP_NOFAIL); eb->start = start; eb->len = len; eb->fs_info = fs_info; init_rwsem(&eb->lock); btrfs_leak_debug_add_eb(eb); spin_lock_init(&eb->refs_lock); atomic_set(&eb->refs, 1); ASSERT(len <= BTRFS_MAX_METADATA_BLOCKSIZE); return eb; } struct extent_buffer *btrfs_clone_extent_buffer(const struct extent_buffer *src) { struct extent_buffer *new; int num_folios = num_extent_folios(src); int ret; new = __alloc_extent_buffer(src->fs_info, src->start, src->len); if (new == NULL) return NULL; /* * Set UNMAPPED before calling btrfs_release_extent_buffer(), as * btrfs_release_extent_buffer() have different behavior for * UNMAPPED subpage extent buffer. */ set_bit(EXTENT_BUFFER_UNMAPPED, &new->bflags); ret = alloc_eb_folio_array(new, 0); if (ret) { btrfs_release_extent_buffer(new); return NULL; } for (int i = 0; i < num_folios; i++) { struct folio *folio = new->folios[i]; int ret; ret = attach_extent_buffer_folio(new, folio, NULL); if (ret < 0) { btrfs_release_extent_buffer(new); return NULL; } WARN_ON(folio_test_dirty(folio)); } copy_extent_buffer_full(new, src); set_extent_buffer_uptodate(new); return new; } struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info, u64 start, unsigned long len) { struct extent_buffer *eb; int num_folios = 0; int ret; eb = __alloc_extent_buffer(fs_info, start, len); if (!eb) return NULL; ret = alloc_eb_folio_array(eb, 0); if (ret) goto err; num_folios = num_extent_folios(eb); for (int i = 0; i < num_folios; i++) { ret = attach_extent_buffer_folio(eb, eb->folios[i], NULL); if (ret < 0) goto err; } set_extent_buffer_uptodate(eb); btrfs_set_header_nritems(eb, 0); set_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags); return eb; err: for (int i = 0; i < num_folios; i++) { if (eb->folios[i]) { detach_extent_buffer_folio(eb, eb->folios[i]); __folio_put(eb->folios[i]); } } __free_extent_buffer(eb); return NULL; } struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info, u64 start) { return __alloc_dummy_extent_buffer(fs_info, start, fs_info->nodesize); } static void check_buffer_tree_ref(struct extent_buffer *eb) { int refs; /* * The TREE_REF bit is first set when the extent_buffer is added * to the radix tree. It is also reset, if unset, when a new reference * is created by find_extent_buffer. * * It is only cleared in two cases: freeing the last non-tree * reference to the extent_buffer when its STALE bit is set or * calling release_folio when the tree reference is the only reference. * * In both cases, care is taken to ensure that the extent_buffer's * pages are not under io. However, release_folio can be concurrently * called with creating new references, which is prone to race * conditions between the calls to check_buffer_tree_ref in those * codepaths and clearing TREE_REF in try_release_extent_buffer. * * The actual lifetime of the extent_buffer in the radix tree is * adequately protected by the refcount, but the TREE_REF bit and * its corresponding reference are not. To protect against this * class of races, we call check_buffer_tree_ref from the codepaths * which trigger io. Note that once io is initiated, TREE_REF can no * longer be cleared, so that is the moment at which any such race is * best fixed. */ refs = atomic_read(&eb->refs); if (refs >= 2 && test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) return; spin_lock(&eb->refs_lock); if (!test_and_set_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) atomic_inc(&eb->refs); spin_unlock(&eb->refs_lock); } static void mark_extent_buffer_accessed(struct extent_buffer *eb) { int num_folios= num_extent_folios(eb); check_buffer_tree_ref(eb); for (int i = 0; i < num_folios; i++) folio_mark_accessed(eb->folios[i]); } struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info, u64 start) { struct extent_buffer *eb; eb = find_extent_buffer_nolock(fs_info, start); if (!eb) return NULL; /* * Lock our eb's refs_lock to avoid races with free_extent_buffer(). * When we get our eb it might be flagged with EXTENT_BUFFER_STALE and * another task running free_extent_buffer() might have seen that flag * set, eb->refs == 2, that the buffer isn't under IO (dirty and * writeback flags not set) and it's still in the tree (flag * EXTENT_BUFFER_TREE_REF set), therefore being in the process of * decrementing the extent buffer's reference count twice. So here we * could race and increment the eb's reference count, clear its stale * flag, mark it as dirty and drop our reference before the other task * finishes executing free_extent_buffer, which would later result in * an attempt to free an extent buffer that is dirty. */ if (test_bit(EXTENT_BUFFER_STALE, &eb->bflags)) { spin_lock(&eb->refs_lock); spin_unlock(&eb->refs_lock); } mark_extent_buffer_accessed(eb); return eb; } #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info, u64 start) { struct extent_buffer *eb, *exists = NULL; int ret; eb = find_extent_buffer(fs_info, start); if (eb) return eb; eb = alloc_dummy_extent_buffer(fs_info, start); if (!eb) return ERR_PTR(-ENOMEM); eb->fs_info = fs_info; again: ret = radix_tree_preload(GFP_NOFS); if (ret) { exists = ERR_PTR(ret); goto free_eb; } spin_lock(&fs_info->buffer_lock); ret = radix_tree_insert(&fs_info->buffer_radix, start >> fs_info->sectorsize_bits, eb); spin_unlock(&fs_info->buffer_lock); radix_tree_preload_end(); if (ret == -EEXIST) { exists = find_extent_buffer(fs_info, start); if (exists) goto free_eb; else goto again; } check_buffer_tree_ref(eb); set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags); return eb; free_eb: btrfs_release_extent_buffer(eb); return exists; } #endif static struct extent_buffer *grab_extent_buffer( struct btrfs_fs_info *fs_info, struct page *page) { struct folio *folio = page_folio(page); struct extent_buffer *exists; /* * For subpage case, we completely rely on radix tree to ensure we * don't try to insert two ebs for the same bytenr. So here we always * return NULL and just continue. */ if (fs_info->nodesize < PAGE_SIZE) return NULL; /* Page not yet attached to an extent buffer */ if (!folio_test_private(folio)) return NULL; /* * We could have already allocated an eb for this page and attached one * so lets see if we can get a ref on the existing eb, and if we can we * know it's good and we can just return that one, else we know we can * just overwrite folio private. */ exists = folio_get_private(folio); if (atomic_inc_not_zero(&exists->refs)) return exists; WARN_ON(PageDirty(page)); folio_detach_private(folio); return NULL; } static int check_eb_alignment(struct btrfs_fs_info *fs_info, u64 start) { if (!IS_ALIGNED(start, fs_info->sectorsize)) { btrfs_err(fs_info, "bad tree block start %llu", start); return -EINVAL; } if (fs_info->nodesize < PAGE_SIZE && offset_in_page(start) + fs_info->nodesize > PAGE_SIZE) { btrfs_err(fs_info, "tree block crosses page boundary, start %llu nodesize %u", start, fs_info->nodesize); return -EINVAL; } if (fs_info->nodesize >= PAGE_SIZE && !PAGE_ALIGNED(start)) { btrfs_err(fs_info, "tree block is not page aligned, start %llu nodesize %u", start, fs_info->nodesize); return -EINVAL; } if (!IS_ALIGNED(start, fs_info->nodesize) && !test_and_set_bit(BTRFS_FS_UNALIGNED_TREE_BLOCK, &fs_info->flags)) { btrfs_warn(fs_info, "tree block not nodesize aligned, start %llu nodesize %u, can be resolved by a full metadata balance", start, fs_info->nodesize); } return 0; } /* * Return 0 if eb->folios[i] is attached to btree inode successfully. * Return >0 if there is already another extent buffer for the range, * and @found_eb_ret would be updated. * Return -EAGAIN if the filemap has an existing folio but with different size * than @eb. * The caller needs to free the existing folios and retry using the same order. */ static int attach_eb_folio_to_filemap(struct extent_buffer *eb, int i, struct extent_buffer **found_eb_ret) { struct btrfs_fs_info *fs_info = eb->fs_info; struct address_space *mapping = fs_info->btree_inode->i_mapping; const unsigned long index = eb->start >> PAGE_SHIFT; struct folio *existing_folio; int ret; ASSERT(found_eb_ret); /* Caller should ensure the folio exists. */ ASSERT(eb->folios[i]); retry: ret = filemap_add_folio(mapping, eb->folios[i], index + i, GFP_NOFS | __GFP_NOFAIL); if (!ret) return 0; existing_folio = filemap_lock_folio(mapping, index + i); /* The page cache only exists for a very short time, just retry. */ if (IS_ERR(existing_folio)) goto retry; /* For now, we should only have single-page folios for btree inode. */ ASSERT(folio_nr_pages(existing_folio) == 1); if (folio_size(existing_folio) != eb->folio_size) { folio_unlock(existing_folio); folio_put(existing_folio); return -EAGAIN; } if (fs_info->nodesize < PAGE_SIZE) { /* * We're going to reuse the existing page, can drop our page * and subpage structure now. */ __free_page(folio_page(eb->folios[i], 0)); eb->folios[i] = existing_folio; } else { struct extent_buffer *existing_eb; existing_eb = grab_extent_buffer(fs_info, folio_page(existing_folio, 0)); if (existing_eb) { /* The extent buffer still exists, we can use it directly. */ *found_eb_ret = existing_eb; folio_unlock(existing_folio); folio_put(existing_folio); return 1; } /* The extent buffer no longer exists, we can reuse the folio. */ __free_page(folio_page(eb->folios[i], 0)); eb->folios[i] = existing_folio; } return 0; } struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start, u64 owner_root, int level) { unsigned long len = fs_info->nodesize; int num_folios; int attached = 0; struct extent_buffer *eb; struct extent_buffer *existing_eb = NULL; struct address_space *mapping = fs_info->btree_inode->i_mapping; struct btrfs_subpage *prealloc = NULL; u64 lockdep_owner = owner_root; bool page_contig = true; int uptodate = 1; int ret; if (check_eb_alignment(fs_info, start)) return ERR_PTR(-EINVAL); #if BITS_PER_LONG == 32 if (start >= MAX_LFS_FILESIZE) { btrfs_err_rl(fs_info, "extent buffer %llu is beyond 32bit page cache limit", start); btrfs_err_32bit_limit(fs_info); return ERR_PTR(-EOVERFLOW); } if (start >= BTRFS_32BIT_EARLY_WARN_THRESHOLD) btrfs_warn_32bit_limit(fs_info); #endif eb = find_extent_buffer(fs_info, start); if (eb) return eb; eb = __alloc_extent_buffer(fs_info, start, len); if (!eb) return ERR_PTR(-ENOMEM); /* * The reloc trees are just snapshots, so we need them to appear to be * just like any other fs tree WRT lockdep. */ if (lockdep_owner == BTRFS_TREE_RELOC_OBJECTID) lockdep_owner = BTRFS_FS_TREE_OBJECTID; btrfs_set_buffer_lockdep_class(lockdep_owner, eb, level); /* * Preallocate folio private for subpage case, so that we won't * allocate memory with i_private_lock nor page lock hold. * * The memory will be freed by attach_extent_buffer_page() or freed * manually if we exit earlier. */ if (fs_info->nodesize < PAGE_SIZE) { prealloc = btrfs_alloc_subpage(fs_info, BTRFS_SUBPAGE_METADATA); if (IS_ERR(prealloc)) { ret = PTR_ERR(prealloc); goto out; } } reallocate: /* Allocate all pages first. */ ret = alloc_eb_folio_array(eb, __GFP_NOFAIL); if (ret < 0) { btrfs_free_subpage(prealloc); goto out; } num_folios = num_extent_folios(eb); /* Attach all pages to the filemap. */ for (int i = 0; i < num_folios; i++) { struct folio *folio; ret = attach_eb_folio_to_filemap(eb, i, &existing_eb); if (ret > 0) { ASSERT(existing_eb); goto out; } /* * TODO: Special handling for a corner case where the order of * folios mismatch between the new eb and filemap. * * This happens when: * * - the new eb is using higher order folio * * - the filemap is still using 0-order folios for the range * This can happen at the previous eb allocation, and we don't * have higher order folio for the call. * * - the existing eb has already been freed * * In this case, we have to free the existing folios first, and * re-allocate using the same order. * Thankfully this is not going to happen yet, as we're still * using 0-order folios. */ if (unlikely(ret == -EAGAIN)) { ASSERT(0); goto reallocate; } attached++; /* * Only after attach_eb_folio_to_filemap(), eb->folios[] is * reliable, as we may choose to reuse the existing page cache * and free the allocated page. */ folio = eb->folios[i]; eb->folio_size = folio_size(folio); eb->folio_shift = folio_shift(folio); spin_lock(&mapping->i_private_lock); /* Should not fail, as we have preallocated the memory */ ret = attach_extent_buffer_folio(eb, folio, prealloc); ASSERT(!ret); /* * To inform we have extra eb under allocation, so that * detach_extent_buffer_page() won't release the folio private * when the eb hasn't yet been inserted into radix tree. * * The ref will be decreased when the eb released the page, in * detach_extent_buffer_page(). * Thus needs no special handling in error path. */ btrfs_folio_inc_eb_refs(fs_info, folio); spin_unlock(&mapping->i_private_lock); WARN_ON(btrfs_folio_test_dirty(fs_info, folio, eb->start, eb->len)); /* * Check if the current page is physically contiguous with previous eb * page. * At this stage, either we allocated a large folio, thus @i * would only be 0, or we fall back to per-page allocation. */ if (i && folio_page(eb->folios[i - 1], 0) + 1 != folio_page(folio, 0)) page_contig = false; if (!btrfs_folio_test_uptodate(fs_info, folio, eb->start, eb->len)) uptodate = 0; /* * We can't unlock the pages just yet since the extent buffer * hasn't been properly inserted in the radix tree, this * opens a race with btree_release_folio which can free a page * while we are still filling in all pages for the buffer and * we could crash. */ } if (uptodate) set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); /* All pages are physically contiguous, can skip cross page handling. */ if (page_contig) eb->addr = folio_address(eb->folios[0]) + offset_in_page(eb->start); again: ret = radix_tree_preload(GFP_NOFS); if (ret) goto out; spin_lock(&fs_info->buffer_lock); ret = radix_tree_insert(&fs_info->buffer_radix, start >> fs_info->sectorsize_bits, eb); spin_unlock(&fs_info->buffer_lock); radix_tree_preload_end(); if (ret == -EEXIST) { ret = 0; existing_eb = find_extent_buffer(fs_info, start); if (existing_eb) goto out; else goto again; } /* add one reference for the tree */ check_buffer_tree_ref(eb); set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags); /* * Now it's safe to unlock the pages because any calls to * btree_release_folio will correctly detect that a page belongs to a * live buffer and won't free them prematurely. */ for (int i = 0; i < num_folios; i++) unlock_page(folio_page(eb->folios[i], 0)); return eb; out: WARN_ON(!atomic_dec_and_test(&eb->refs)); /* * Any attached folios need to be detached before we unlock them. This * is because when we're inserting our new folios into the mapping, and * then attaching our eb to that folio. If we fail to insert our folio * we'll lookup the folio for that index, and grab that EB. We do not * want that to grab this eb, as we're getting ready to free it. So we * have to detach it first and then unlock it. * * We have to drop our reference and NULL it out here because in the * subpage case detaching does a btrfs_folio_dec_eb_refs() for our eb. * Below when we call btrfs_release_extent_buffer() we will call * detach_extent_buffer_folio() on our remaining pages in the !subpage * case. If we left eb->folios[i] populated in the subpage case we'd * double put our reference and be super sad. */ for (int i = 0; i < attached; i++) { ASSERT(eb->folios[i]); detach_extent_buffer_folio(eb, eb->folios[i]); unlock_page(folio_page(eb->folios[i], 0)); folio_put(eb->folios[i]); eb->folios[i] = NULL; } /* * Now all pages of that extent buffer is unmapped, set UNMAPPED flag, * so it can be cleaned up without utlizing page->mapping. */ set_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags); btrfs_release_extent_buffer(eb); if (ret < 0) return ERR_PTR(ret); ASSERT(existing_eb); return existing_eb; } static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head) { struct extent_buffer *eb = container_of(head, struct extent_buffer, rcu_head); __free_extent_buffer(eb); } static int release_extent_buffer(struct extent_buffer *eb) __releases(&eb->refs_lock) { lockdep_assert_held(&eb->refs_lock); WARN_ON(atomic_read(&eb->refs) == 0); if (atomic_dec_and_test(&eb->refs)) { if (test_and_clear_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags)) { struct btrfs_fs_info *fs_info = eb->fs_info; spin_unlock(&eb->refs_lock); spin_lock(&fs_info->buffer_lock); radix_tree_delete(&fs_info->buffer_radix, eb->start >> fs_info->sectorsize_bits); spin_unlock(&fs_info->buffer_lock); } else { spin_unlock(&eb->refs_lock); } btrfs_leak_debug_del_eb(eb); /* Should be safe to release our pages at this point */ btrfs_release_extent_buffer_pages(eb); #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS if (unlikely(test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags))) { __free_extent_buffer(eb); return 1; } #endif call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu); return 1; } spin_unlock(&eb->refs_lock); return 0; } void free_extent_buffer(struct extent_buffer *eb) { int refs; if (!eb) return; refs = atomic_read(&eb->refs); while (1) { if ((!test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags) && refs <= 3) || (test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags) && refs == 1)) break; if (atomic_try_cmpxchg(&eb->refs, &refs, refs - 1)) return; } spin_lock(&eb->refs_lock); if (atomic_read(&eb->refs) == 2 && test_bit(EXTENT_BUFFER_STALE, &eb->bflags) && !extent_buffer_under_io(eb) && test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) atomic_dec(&eb->refs); /* * I know this is terrible, but it's temporary until we stop tracking * the uptodate bits and such for the extent buffers. */ release_extent_buffer(eb); } void free_extent_buffer_stale(struct extent_buffer *eb) { if (!eb) return; spin_lock(&eb->refs_lock); set_bit(EXTENT_BUFFER_STALE, &eb->bflags); if (atomic_read(&eb->refs) == 2 && !extent_buffer_under_io(eb) && test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) atomic_dec(&eb->refs); release_extent_buffer(eb); } static void btree_clear_folio_dirty(struct folio *folio) { ASSERT(folio_test_dirty(folio)); ASSERT(folio_test_locked(folio)); folio_clear_dirty_for_io(folio); xa_lock_irq(&folio->mapping->i_pages); if (!folio_test_dirty(folio)) __xa_clear_mark(&folio->mapping->i_pages, folio_index(folio), PAGECACHE_TAG_DIRTY); xa_unlock_irq(&folio->mapping->i_pages); } static void clear_subpage_extent_buffer_dirty(const struct extent_buffer *eb) { struct btrfs_fs_info *fs_info = eb->fs_info; struct folio *folio = eb->folios[0]; bool last; /* btree_clear_folio_dirty() needs page locked. */ folio_lock(folio); last = btrfs_subpage_clear_and_test_dirty(fs_info, folio, eb->start, eb->len); if (last) btree_clear_folio_dirty(folio); folio_unlock(folio); WARN_ON(atomic_read(&eb->refs) == 0); } void btrfs_clear_buffer_dirty(struct btrfs_trans_handle *trans, struct extent_buffer *eb) { struct btrfs_fs_info *fs_info = eb->fs_info; int num_folios; btrfs_assert_tree_write_locked(eb); if (trans && btrfs_header_generation(eb) != trans->transid) return; /* * Instead of clearing the dirty flag off of the buffer, mark it as * EXTENT_BUFFER_ZONED_ZEROOUT. This allows us to preserve * write-ordering in zoned mode, without the need to later re-dirty * the extent_buffer. * * The actual zeroout of the buffer will happen later in * btree_csum_one_bio. */ if (btrfs_is_zoned(fs_info) && test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) { set_bit(EXTENT_BUFFER_ZONED_ZEROOUT, &eb->bflags); return; } if (!test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) return; percpu_counter_add_batch(&fs_info->dirty_metadata_bytes, -eb->len, fs_info->dirty_metadata_batch); if (eb->fs_info->nodesize < PAGE_SIZE) return clear_subpage_extent_buffer_dirty(eb); num_folios = num_extent_folios(eb); for (int i = 0; i < num_folios; i++) { struct folio *folio = eb->folios[i]; if (!folio_test_dirty(folio)) continue; folio_lock(folio); btree_clear_folio_dirty(folio); folio_unlock(folio); } WARN_ON(atomic_read(&eb->refs) == 0); } void set_extent_buffer_dirty(struct extent_buffer *eb) { int num_folios; bool was_dirty; check_buffer_tree_ref(eb); was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags); num_folios = num_extent_folios(eb); WARN_ON(atomic_read(&eb->refs) == 0); WARN_ON(!test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)); WARN_ON(test_bit(EXTENT_BUFFER_ZONED_ZEROOUT, &eb->bflags)); if (!was_dirty) { bool subpage = eb->fs_info->nodesize < PAGE_SIZE; /* * For subpage case, we can have other extent buffers in the * same page, and in clear_subpage_extent_buffer_dirty() we * have to clear page dirty without subpage lock held. * This can cause race where our page gets dirty cleared after * we just set it. * * Thankfully, clear_subpage_extent_buffer_dirty() has locked * its page for other reasons, we can use page lock to prevent * the above race. */ if (subpage) lock_page(folio_page(eb->folios[0], 0)); for (int i = 0; i < num_folios; i++) btrfs_folio_set_dirty(eb->fs_info, eb->folios[i], eb->start, eb->len); if (subpage) unlock_page(folio_page(eb->folios[0], 0)); percpu_counter_add_batch(&eb->fs_info->dirty_metadata_bytes, eb->len, eb->fs_info->dirty_metadata_batch); } #ifdef CONFIG_BTRFS_DEBUG for (int i = 0; i < num_folios; i++) ASSERT(folio_test_dirty(eb->folios[i])); #endif } void clear_extent_buffer_uptodate(struct extent_buffer *eb) { struct btrfs_fs_info *fs_info = eb->fs_info; int num_folios = num_extent_folios(eb); clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); for (int i = 0; i < num_folios; i++) { struct folio *folio = eb->folios[i]; if (!folio) continue; /* * This is special handling for metadata subpage, as regular * btrfs_is_subpage() can not handle cloned/dummy metadata. */ if (fs_info->nodesize >= PAGE_SIZE) folio_clear_uptodate(folio); else btrfs_subpage_clear_uptodate(fs_info, folio, eb->start, eb->len); } } void set_extent_buffer_uptodate(struct extent_buffer *eb) { struct btrfs_fs_info *fs_info = eb->fs_info; int num_folios = num_extent_folios(eb); set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); for (int i = 0; i < num_folios; i++) { struct folio *folio = eb->folios[i]; /* * This is special handling for metadata subpage, as regular * btrfs_is_subpage() can not handle cloned/dummy metadata. */ if (fs_info->nodesize >= PAGE_SIZE) folio_mark_uptodate(folio); else btrfs_subpage_set_uptodate(fs_info, folio, eb->start, eb->len); } } static void end_bbio_meta_read(struct btrfs_bio *bbio) { struct extent_buffer *eb = bbio->private; struct btrfs_fs_info *fs_info = eb->fs_info; bool uptodate = !bbio->bio.bi_status; struct folio_iter fi; u32 bio_offset = 0; eb->read_mirror = bbio->mirror_num; if (uptodate && btrfs_validate_extent_buffer(eb, &bbio->parent_check) < 0) uptodate = false; if (uptodate) { set_extent_buffer_uptodate(eb); } else { clear_extent_buffer_uptodate(eb); set_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags); } bio_for_each_folio_all(fi, &bbio->bio) { struct folio *folio = fi.folio; u64 start = eb->start + bio_offset; u32 len = fi.length; if (uptodate) btrfs_folio_set_uptodate(fs_info, folio, start, len); else btrfs_folio_clear_uptodate(fs_info, folio, start, len); bio_offset += len; } clear_bit(EXTENT_BUFFER_READING, &eb->bflags); smp_mb__after_atomic(); wake_up_bit(&eb->bflags, EXTENT_BUFFER_READING); free_extent_buffer(eb); bio_put(&bbio->bio); } int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num, struct btrfs_tree_parent_check *check) { struct btrfs_bio *bbio; bool ret; if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) return 0; /* * We could have had EXTENT_BUFFER_UPTODATE cleared by the write * operation, which could potentially still be in flight. In this case * we simply want to return an error. */ if (unlikely(test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags))) return -EIO; /* Someone else is already reading the buffer, just wait for it. */ if (test_and_set_bit(EXTENT_BUFFER_READING, &eb->bflags)) goto done; /* * Between the initial test_bit(EXTENT_BUFFER_UPTODATE) and the above * test_and_set_bit(EXTENT_BUFFER_READING), someone else could have * started and finished reading the same eb. In this case, UPTODATE * will now be set, and we shouldn't read it in again. */ if (unlikely(test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))) { clear_bit(EXTENT_BUFFER_READING, &eb->bflags); smp_mb__after_atomic(); wake_up_bit(&eb->bflags, EXTENT_BUFFER_READING); return 0; } clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags); eb->read_mirror = 0; check_buffer_tree_ref(eb); atomic_inc(&eb->refs); bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES, REQ_OP_READ | REQ_META, eb->fs_info, end_bbio_meta_read, eb); bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT; bbio->inode = BTRFS_I(eb->fs_info->btree_inode); bbio->file_offset = eb->start; memcpy(&bbio->parent_check, check, sizeof(*check)); if (eb->fs_info->nodesize < PAGE_SIZE) { ret = bio_add_folio(&bbio->bio, eb->folios[0], eb->len, eb->start - folio_pos(eb->folios[0])); ASSERT(ret); } else { int num_folios = num_extent_folios(eb); for (int i = 0; i < num_folios; i++) { struct folio *folio = eb->folios[i]; ret = bio_add_folio(&bbio->bio, folio, eb->folio_size, 0); ASSERT(ret); } } btrfs_submit_bio(bbio, mirror_num); done: if (wait == WAIT_COMPLETE) { wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_READING, TASK_UNINTERRUPTIBLE); if (!test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) return -EIO; } return 0; } static bool report_eb_range(const struct extent_buffer *eb, unsigned long start, unsigned long len) { btrfs_warn(eb->fs_info, "access to eb bytenr %llu len %u out of range start %lu len %lu", eb->start, eb->len, start, len); WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)); return true; } /* * Check if the [start, start + len) range is valid before reading/writing * the eb. * NOTE: @start and @len are offset inside the eb, not logical address. * * Caller should not touch the dst/src memory if this function returns error. */ static inline int check_eb_range(const struct extent_buffer *eb, unsigned long start, unsigned long len) { unsigned long offset; /* start, start + len should not go beyond eb->len nor overflow */ if (unlikely(check_add_overflow(start, len, &offset) || offset > eb->len)) return report_eb_range(eb, start, len); return false; } void read_extent_buffer(const struct extent_buffer *eb, void *dstv, unsigned long start, unsigned long len) { const int unit_size = eb->folio_size; size_t cur; size_t offset; char *dst = (char *)dstv; unsigned long i = get_eb_folio_index(eb, start); if (check_eb_range(eb, start, len)) { /* * Invalid range hit, reset the memory, so callers won't get * some random garbage for their uninitialized memory. */ memset(dstv, 0, len); return; } if (eb->addr) { memcpy(dstv, eb->addr + start, len); return; } offset = get_eb_offset_in_folio(eb, start); while (len > 0) { char *kaddr; cur = min(len, unit_size - offset); kaddr = folio_address(eb->folios[i]); memcpy(dst, kaddr + offset, cur); dst += cur; len -= cur; offset = 0; i++; } } int read_extent_buffer_to_user_nofault(const struct extent_buffer *eb, void __user *dstv, unsigned long start, unsigned long len) { const int unit_size = eb->folio_size; size_t cur; size_t offset; char __user *dst = (char __user *)dstv; unsigned long i = get_eb_folio_index(eb, start); int ret = 0; WARN_ON(start > eb->len); WARN_ON(start + len > eb->start + eb->len); if (eb->addr) { if (copy_to_user_nofault(dstv, eb->addr + start, len)) ret = -EFAULT; return ret; } offset = get_eb_offset_in_folio(eb, start); while (len > 0) { char *kaddr; cur = min(len, unit_size - offset); kaddr = folio_address(eb->folios[i]); if (copy_to_user_nofault(dst, kaddr + offset, cur)) { ret = -EFAULT; break; } dst += cur; len -= cur; offset = 0; i++; } return ret; } int memcmp_extent_buffer(const struct extent_buffer *eb, const void *ptrv, unsigned long start, unsigned long len) { const int unit_size = eb->folio_size; size_t cur; size_t offset; char *kaddr; char *ptr = (char *)ptrv; unsigned long i = get_eb_folio_index(eb, start); int ret = 0; if (check_eb_range(eb, start, len)) return -EINVAL; if (eb->addr) return memcmp(ptrv, eb->addr + start, len); offset = get_eb_offset_in_folio(eb, start); while (len > 0) { cur = min(len, unit_size - offset); kaddr = folio_address(eb->folios[i]); ret = memcmp(ptr, kaddr + offset, cur); if (ret) break; ptr += cur; len -= cur; offset = 0; i++; } return ret; } /* * Check that the extent buffer is uptodate. * * For regular sector size == PAGE_SIZE case, check if @page is uptodate. * For subpage case, check if the range covered by the eb has EXTENT_UPTODATE. */ static void assert_eb_folio_uptodate(const struct extent_buffer *eb, int i) { struct btrfs_fs_info *fs_info = eb->fs_info; struct folio *folio = eb->folios[i]; ASSERT(folio); /* * If we are using the commit root we could potentially clear a page * Uptodate while we're using the extent buffer that we've previously * looked up. We don't want to complain in this case, as the page was * valid before, we just didn't write it out. Instead we want to catch * the case where we didn't actually read the block properly, which * would have !PageUptodate and !EXTENT_BUFFER_WRITE_ERR. */ if (test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)) return; if (fs_info->nodesize < PAGE_SIZE) { struct folio *folio = eb->folios[0]; ASSERT(i == 0); if (WARN_ON(!btrfs_subpage_test_uptodate(fs_info, folio, eb->start, eb->len))) btrfs_subpage_dump_bitmap(fs_info, folio, eb->start, eb->len); } else { WARN_ON(!folio_test_uptodate(folio)); } } static void __write_extent_buffer(const struct extent_buffer *eb, const void *srcv, unsigned long start, unsigned long len, bool use_memmove) { const int unit_size = eb->folio_size; size_t cur; size_t offset; char *kaddr; char *src = (char *)srcv; unsigned long i = get_eb_folio_index(eb, start); /* For unmapped (dummy) ebs, no need to check their uptodate status. */ const bool check_uptodate = !test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags); if (check_eb_range(eb, start, len)) return; if (eb->addr) { if (use_memmove) memmove(eb->addr + start, srcv, len); else memcpy(eb->addr + start, srcv, len); return; } offset = get_eb_offset_in_folio(eb, start); while (len > 0) { if (check_uptodate) assert_eb_folio_uptodate(eb, i); cur = min(len, unit_size - offset); kaddr = folio_address(eb->folios[i]); if (use_memmove) memmove(kaddr + offset, src, cur); else memcpy(kaddr + offset, src, cur); src += cur; len -= cur; offset = 0; i++; } } void write_extent_buffer(const struct extent_buffer *eb, const void *srcv, unsigned long start, unsigned long len) { return __write_extent_buffer(eb, srcv, start, len, false); } static void memset_extent_buffer(const struct extent_buffer *eb, int c, unsigned long start, unsigned long len) { const int unit_size = eb->folio_size; unsigned long cur = start; if (eb->addr) { memset(eb->addr + start, c, len); return; } while (cur < start + len) { unsigned long index = get_eb_folio_index(eb, cur); unsigned int offset = get_eb_offset_in_folio(eb, cur); unsigned int cur_len = min(start + len - cur, unit_size - offset); assert_eb_folio_uptodate(eb, index); memset(folio_address(eb->folios[index]) + offset, c, cur_len); cur += cur_len; } } void memzero_extent_buffer(const struct extent_buffer *eb, unsigned long start, unsigned long len) { if (check_eb_range(eb, start, len)) return; return memset_extent_buffer(eb, 0, start, len); } void copy_extent_buffer_full(const struct extent_buffer *dst, const struct extent_buffer *src) { const int unit_size = src->folio_size; unsigned long cur = 0; ASSERT(dst->len == src->len); while (cur < src->len) { unsigned long index = get_eb_folio_index(src, cur); unsigned long offset = get_eb_offset_in_folio(src, cur); unsigned long cur_len = min(src->len, unit_size - offset); void *addr = folio_address(src->folios[index]) + offset; write_extent_buffer(dst, addr, cur, cur_len); cur += cur_len; } } void copy_extent_buffer(const struct extent_buffer *dst, const struct extent_buffer *src, unsigned long dst_offset, unsigned long src_offset, unsigned long len) { const int unit_size = dst->folio_size; u64 dst_len = dst->len; size_t cur; size_t offset; char *kaddr; unsigned long i = get_eb_folio_index(dst, dst_offset); if (check_eb_range(dst, dst_offset, len) || check_eb_range(src, src_offset, len)) return; WARN_ON(src->len != dst_len); offset = get_eb_offset_in_folio(dst, dst_offset); while (len > 0) { assert_eb_folio_uptodate(dst, i); cur = min(len, (unsigned long)(unit_size - offset)); kaddr = folio_address(dst->folios[i]); read_extent_buffer(src, kaddr + offset, src_offset, cur); src_offset += cur; len -= cur; offset = 0; i++; } } /* * Calculate the folio and offset of the byte containing the given bit number. * * @eb: the extent buffer * @start: offset of the bitmap item in the extent buffer * @nr: bit number * @folio_index: return index of the folio in the extent buffer that contains * the given bit number * @folio_offset: return offset into the folio given by folio_index * * This helper hides the ugliness of finding the byte in an extent buffer which * contains a given bit. */ static inline void eb_bitmap_offset(const struct extent_buffer *eb, unsigned long start, unsigned long nr, unsigned long *folio_index, size_t *folio_offset) { size_t byte_offset = BIT_BYTE(nr); size_t offset; /* * The byte we want is the offset of the extent buffer + the offset of * the bitmap item in the extent buffer + the offset of the byte in the * bitmap item. */ offset = start + offset_in_eb_folio(eb, eb->start) + byte_offset; *folio_index = offset >> eb->folio_shift; *folio_offset = offset_in_eb_folio(eb, offset); } /* * Determine whether a bit in a bitmap item is set. * * @eb: the extent buffer * @start: offset of the bitmap item in the extent buffer * @nr: bit number to test */ int extent_buffer_test_bit(const struct extent_buffer *eb, unsigned long start, unsigned long nr) { unsigned long i; size_t offset; u8 *kaddr; eb_bitmap_offset(eb, start, nr, &i, &offset); assert_eb_folio_uptodate(eb, i); kaddr = folio_address(eb->folios[i]); return 1U & (kaddr[offset] >> (nr & (BITS_PER_BYTE - 1))); } static u8 *extent_buffer_get_byte(const struct extent_buffer *eb, unsigned long bytenr) { unsigned long index = get_eb_folio_index(eb, bytenr); if (check_eb_range(eb, bytenr, 1)) return NULL; return folio_address(eb->folios[index]) + get_eb_offset_in_folio(eb, bytenr); } /* * Set an area of a bitmap to 1. * * @eb: the extent buffer * @start: offset of the bitmap item in the extent buffer * @pos: bit number of the first bit * @len: number of bits to set */ void extent_buffer_bitmap_set(const struct extent_buffer *eb, unsigned long start, unsigned long pos, unsigned long len) { unsigned int first_byte = start + BIT_BYTE(pos); unsigned int last_byte = start + BIT_BYTE(pos + len - 1); const bool same_byte = (first_byte == last_byte); u8 mask = BITMAP_FIRST_BYTE_MASK(pos); u8 *kaddr; if (same_byte) mask &= BITMAP_LAST_BYTE_MASK(pos + len); /* Handle the first byte. */ kaddr = extent_buffer_get_byte(eb, first_byte); *kaddr |= mask; if (same_byte) return; /* Handle the byte aligned part. */ ASSERT(first_byte + 1 <= last_byte); memset_extent_buffer(eb, 0xff, first_byte + 1, last_byte - first_byte - 1); /* Handle the last byte. */ kaddr = extent_buffer_get_byte(eb, last_byte); *kaddr |= BITMAP_LAST_BYTE_MASK(pos + len); } /* * Clear an area of a bitmap. * * @eb: the extent buffer * @start: offset of the bitmap item in the extent buffer * @pos: bit number of the first bit * @len: number of bits to clear */ void extent_buffer_bitmap_clear(const struct extent_buffer *eb, unsigned long start, unsigned long pos, unsigned long len) { unsigned int first_byte = start + BIT_BYTE(pos); unsigned int last_byte = start + BIT_BYTE(pos + len - 1); const bool same_byte = (first_byte == last_byte); u8 mask = BITMAP_FIRST_BYTE_MASK(pos); u8 *kaddr; if (same_byte) mask &= BITMAP_LAST_BYTE_MASK(pos + len); /* Handle the first byte. */ kaddr = extent_buffer_get_byte(eb, first_byte); *kaddr &= ~mask; if (same_byte) return; /* Handle the byte aligned part. */ ASSERT(first_byte + 1 <= last_byte); memset_extent_buffer(eb, 0, first_byte + 1, last_byte - first_byte - 1); /* Handle the last byte. */ kaddr = extent_buffer_get_byte(eb, last_byte); *kaddr &= ~BITMAP_LAST_BYTE_MASK(pos + len); } static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len) { unsigned long distance = (src > dst) ? src - dst : dst - src; return distance < len; } void memcpy_extent_buffer(const struct extent_buffer *dst, unsigned long dst_offset, unsigned long src_offset, unsigned long len) { const int unit_size = dst->folio_size; unsigned long cur_off = 0; if (check_eb_range(dst, dst_offset, len) || check_eb_range(dst, src_offset, len)) return; if (dst->addr) { const bool use_memmove = areas_overlap(src_offset, dst_offset, len); if (use_memmove) memmove(dst->addr + dst_offset, dst->addr + src_offset, len); else memcpy(dst->addr + dst_offset, dst->addr + src_offset, len); return; } while (cur_off < len) { unsigned long cur_src = cur_off + src_offset; unsigned long folio_index = get_eb_folio_index(dst, cur_src); unsigned long folio_off = get_eb_offset_in_folio(dst, cur_src); unsigned long cur_len = min(src_offset + len - cur_src, unit_size - folio_off); void *src_addr = folio_address(dst->folios[folio_index]) + folio_off; const bool use_memmove = areas_overlap(src_offset + cur_off, dst_offset + cur_off, cur_len); __write_extent_buffer(dst, src_addr, dst_offset + cur_off, cur_len, use_memmove); cur_off += cur_len; } } void memmove_extent_buffer(const struct extent_buffer *dst, unsigned long dst_offset, unsigned long src_offset, unsigned long len) { unsigned long dst_end = dst_offset + len - 1; unsigned long src_end = src_offset + len - 1; if (check_eb_range(dst, dst_offset, len) || check_eb_range(dst, src_offset, len)) return; if (dst_offset < src_offset) { memcpy_extent_buffer(dst, dst_offset, src_offset, len); return; } if (dst->addr) { memmove(dst->addr + dst_offset, dst->addr + src_offset, len); return; } while (len > 0) { unsigned long src_i; size_t cur; size_t dst_off_in_folio; size_t src_off_in_folio; void *src_addr; bool use_memmove; src_i = get_eb_folio_index(dst, src_end); dst_off_in_folio = get_eb_offset_in_folio(dst, dst_end); src_off_in_folio = get_eb_offset_in_folio(dst, src_end); cur = min_t(unsigned long, len, src_off_in_folio + 1); cur = min(cur, dst_off_in_folio + 1); src_addr = folio_address(dst->folios[src_i]) + src_off_in_folio - cur + 1; use_memmove = areas_overlap(src_end - cur + 1, dst_end - cur + 1, cur); __write_extent_buffer(dst, src_addr, dst_end - cur + 1, cur, use_memmove); dst_end -= cur; src_end -= cur; len -= cur; } } #define GANG_LOOKUP_SIZE 16 static struct extent_buffer *get_next_extent_buffer( struct btrfs_fs_info *fs_info, struct page *page, u64 bytenr) { struct extent_buffer *gang[GANG_LOOKUP_SIZE]; struct extent_buffer *found = NULL; u64 page_start = page_offset(page); u64 cur = page_start; ASSERT(in_range(bytenr, page_start, PAGE_SIZE)); lockdep_assert_held(&fs_info->buffer_lock); while (cur < page_start + PAGE_SIZE) { int ret; int i; ret = radix_tree_gang_lookup(&fs_info->buffer_radix, (void **)gang, cur >> fs_info->sectorsize_bits, min_t(unsigned int, GANG_LOOKUP_SIZE, PAGE_SIZE / fs_info->nodesize)); if (ret == 0) goto out; for (i = 0; i < ret; i++) { /* Already beyond page end */ if (gang[i]->start >= page_start + PAGE_SIZE) goto out; /* Found one */ if (gang[i]->start >= bytenr) { found = gang[i]; goto out; } } cur = gang[ret - 1]->start + gang[ret - 1]->len; } out: return found; } static int try_release_subpage_extent_buffer(struct page *page) { struct btrfs_fs_info *fs_info = page_to_fs_info(page); u64 cur = page_offset(page); const u64 end = page_offset(page) + PAGE_SIZE; int ret; while (cur < end) { struct extent_buffer *eb = NULL; /* * Unlike try_release_extent_buffer() which uses folio private * to grab buffer, for subpage case we rely on radix tree, thus * we need to ensure radix tree consistency. * * We also want an atomic snapshot of the radix tree, thus go * with spinlock rather than RCU. */ spin_lock(&fs_info->buffer_lock); eb = get_next_extent_buffer(fs_info, page, cur); if (!eb) { /* No more eb in the page range after or at cur */ spin_unlock(&fs_info->buffer_lock); break; } cur = eb->start + eb->len; /* * The same as try_release_extent_buffer(), to ensure the eb * won't disappear out from under us. */ spin_lock(&eb->refs_lock); if (atomic_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) { spin_unlock(&eb->refs_lock); spin_unlock(&fs_info->buffer_lock); break; } spin_unlock(&fs_info->buffer_lock); /* * If tree ref isn't set then we know the ref on this eb is a * real ref, so just return, this eb will likely be freed soon * anyway. */ if (!test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) { spin_unlock(&eb->refs_lock); break; } /* * Here we don't care about the return value, we will always * check the folio private at the end. And * release_extent_buffer() will release the refs_lock. */ release_extent_buffer(eb); } /* * Finally to check if we have cleared folio private, as if we have * released all ebs in the page, the folio private should be cleared now. */ spin_lock(&page->mapping->i_private_lock); if (!folio_test_private(page_folio(page))) ret = 1; else ret = 0; spin_unlock(&page->mapping->i_private_lock); return ret; } int try_release_extent_buffer(struct page *page) { struct folio *folio = page_folio(page); struct extent_buffer *eb; if (page_to_fs_info(page)->nodesize < PAGE_SIZE) return try_release_subpage_extent_buffer(page); /* * We need to make sure nobody is changing folio private, as we rely on * folio private as the pointer to extent buffer. */ spin_lock(&page->mapping->i_private_lock); if (!folio_test_private(folio)) { spin_unlock(&page->mapping->i_private_lock); return 1; } eb = folio_get_private(folio); BUG_ON(!eb); /* * This is a little awful but should be ok, we need to make sure that * the eb doesn't disappear out from under us while we're looking at * this page. */ spin_lock(&eb->refs_lock); if (atomic_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) { spin_unlock(&eb->refs_lock); spin_unlock(&page->mapping->i_private_lock); return 0; } spin_unlock(&page->mapping->i_private_lock); /* * If tree ref isn't set then we know the ref on this eb is a real ref, * so just return, this page will likely be freed soon anyway. */ if (!test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) { spin_unlock(&eb->refs_lock); return 0; } return release_extent_buffer(eb); } /* * Attempt to readahead a child block. * * @fs_info: the fs_info * @bytenr: bytenr to read * @owner_root: objectid of the root that owns this eb * @gen: generation for the uptodate check, can be 0 * @level: level for the eb * * Attempt to readahead a tree block at @bytenr. If @gen is 0 then we do a * normal uptodate check of the eb, without checking the generation. If we have * to read the block we will not block on anything. */ void btrfs_readahead_tree_block(struct btrfs_fs_info *fs_info, u64 bytenr, u64 owner_root, u64 gen, int level) { struct btrfs_tree_parent_check check = { .has_first_key = 0, .level = level, .transid = gen }; struct extent_buffer *eb; int ret; eb = btrfs_find_create_tree_block(fs_info, bytenr, owner_root, level); if (IS_ERR(eb)) return; if (btrfs_buffer_uptodate(eb, gen, 1)) { free_extent_buffer(eb); return; } ret = read_extent_buffer_pages(eb, WAIT_NONE, 0, &check); if (ret < 0) free_extent_buffer_stale(eb); else free_extent_buffer(eb); } /* * Readahead a node's child block. * * @node: parent node we're reading from * @slot: slot in the parent node for the child we want to read * * A helper for btrfs_readahead_tree_block, we simply read the bytenr pointed at * the slot in the node provided. */ void btrfs_readahead_node_child(struct extent_buffer *node, int slot) { btrfs_readahead_tree_block(node->fs_info, btrfs_node_blockptr(node, slot), btrfs_header_owner(node), btrfs_node_ptr_generation(node, slot), btrfs_header_level(node) - 1); }
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