| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Mikulas Patocka | 6862 | 88.67% | 32 | 46.38% |
| Joe Thornber | 506 | 6.54% | 3 | 4.35% |
| David Chinner | 84 | 1.09% | 1 | 1.45% |
| Aliaksei Karaliou | 53 | 0.68% | 2 | 2.90% |
| Suren Baghdasaryan | 41 | 0.53% | 1 | 1.45% |
| Christoph Hellwig | 29 | 0.37% | 4 | 5.80% |
| Darrick J. Wong | 23 | 0.30% | 1 | 1.45% |
| Eric Biggers | 22 | 0.28% | 1 | 1.45% |
| Michael Christie | 21 | 0.27% | 2 | 2.90% |
| Arnd Bergmann | 21 | 0.27% | 1 | 1.45% |
| Peter Zijlstra | 13 | 0.17% | 2 | 2.90% |
| Neil Brown | 9 | 0.12% | 1 | 1.45% |
| Asaf Vertz | 8 | 0.10% | 1 | 1.45% |
| Mark Rutland | 6 | 0.08% | 1 | 1.45% |
| Wang Sheng-Hui | 6 | 0.08% | 1 | 1.45% |
| Bhaktipriya Shridhar | 5 | 0.06% | 1 | 1.45% |
| Mike Snitzer | 4 | 0.05% | 1 | 1.45% |
| Anup Limbu | 3 | 0.04% | 1 | 1.45% |
| Lei Ming | 3 | 0.04% | 1 | 1.45% |
| Ingo Molnar | 3 | 0.04% | 1 | 1.45% |
| Stephen Rothwell | 3 | 0.04% | 1 | 1.45% |
| Jan Kara | 2 | 0.03% | 1 | 1.45% |
| Kent Overstreet | 2 | 0.03% | 1 | 1.45% |
| Doug Anderson | 2 | 0.03% | 1 | 1.45% |
| Arun K S | 2 | 0.03% | 1 | 1.45% |
| Dan Carpenter | 2 | 0.03% | 1 | 1.45% |
| Greg Thelen | 1 | 0.01% | 1 | 1.45% |
| Davidlohr Bueso A | 1 | 0.01% | 1 | 1.45% |
| Al Viro | 1 | 0.01% | 1 | 1.45% |
| Wei Yongjun | 1 | 0.01% | 1 | 1.45% |
| Total | 7739 | 69 |
/* * Copyright (C) 2009-2011 Red Hat, Inc. * * Author: Mikulas Patocka <mpatocka@redhat.com> * * This file is released under the GPL. */ #include <linux/dm-bufio.h> #include <linux/device-mapper.h> #include <linux/dm-io.h> #include <linux/slab.h> #include <linux/sched/mm.h> #include <linux/jiffies.h> #include <linux/vmalloc.h> #include <linux/shrinker.h> #include <linux/module.h> #include <linux/rbtree.h> #include <linux/stacktrace.h> #define DM_MSG_PREFIX "bufio" /* * Memory management policy: * Limit the number of buffers to DM_BUFIO_MEMORY_PERCENT of main memory * or DM_BUFIO_VMALLOC_PERCENT of vmalloc memory (whichever is lower). * Always allocate at least DM_BUFIO_MIN_BUFFERS buffers. * Start background writeback when there are DM_BUFIO_WRITEBACK_PERCENT * dirty buffers. */ #define DM_BUFIO_MIN_BUFFERS 8 #define DM_BUFIO_MEMORY_PERCENT 2 #define DM_BUFIO_VMALLOC_PERCENT 25 #define DM_BUFIO_WRITEBACK_PERCENT 75 /* * Check buffer ages in this interval (seconds) */ #define DM_BUFIO_WORK_TIMER_SECS 30 /* * Free buffers when they are older than this (seconds) */ #define DM_BUFIO_DEFAULT_AGE_SECS 300 /* * The nr of bytes of cached data to keep around. */ #define DM_BUFIO_DEFAULT_RETAIN_BYTES (256 * 1024) /* * Align buffer writes to this boundary. * Tests show that SSDs have the highest IOPS when using 4k writes. */ #define DM_BUFIO_WRITE_ALIGN 4096 /* * dm_buffer->list_mode */ #define LIST_CLEAN 0 #define LIST_DIRTY 1 #define LIST_SIZE 2 /* * Linking of buffers: * All buffers are linked to buffer_tree with their node field. * * Clean buffers that are not being written (B_WRITING not set) * are linked to lru[LIST_CLEAN] with their lru_list field. * * Dirty and clean buffers that are being written are linked to * lru[LIST_DIRTY] with their lru_list field. When the write * finishes, the buffer cannot be relinked immediately (because we * are in an interrupt context and relinking requires process * context), so some clean-not-writing buffers can be held on * dirty_lru too. They are later added to lru in the process * context. */ struct dm_bufio_client { struct mutex lock; struct list_head lru[LIST_SIZE]; unsigned long n_buffers[LIST_SIZE]; struct block_device *bdev; unsigned block_size; s8 sectors_per_block_bits; void (*alloc_callback)(struct dm_buffer *); void (*write_callback)(struct dm_buffer *); struct kmem_cache *slab_buffer; struct kmem_cache *slab_cache; struct dm_io_client *dm_io; struct list_head reserved_buffers; unsigned need_reserved_buffers; unsigned minimum_buffers; struct rb_root buffer_tree; wait_queue_head_t free_buffer_wait; sector_t start; int async_write_error; struct list_head client_list; struct shrinker shrinker; }; /* * Buffer state bits. */ #define B_READING 0 #define B_WRITING 1 #define B_DIRTY 2 /* * Describes how the block was allocated: * kmem_cache_alloc(), __get_free_pages() or vmalloc(). * See the comment at alloc_buffer_data. */ enum data_mode { DATA_MODE_SLAB = 0, DATA_MODE_GET_FREE_PAGES = 1, DATA_MODE_VMALLOC = 2, DATA_MODE_LIMIT = 3 }; struct dm_buffer { struct rb_node node; struct list_head lru_list; sector_t block; void *data; unsigned char data_mode; /* DATA_MODE_* */ unsigned char list_mode; /* LIST_* */ blk_status_t read_error; blk_status_t write_error; unsigned hold_count; unsigned long state; unsigned long last_accessed; unsigned dirty_start; unsigned dirty_end; unsigned write_start; unsigned write_end; struct dm_bufio_client *c; struct list_head write_list; void (*end_io)(struct dm_buffer *, blk_status_t); #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING #define MAX_STACK 10 struct stack_trace stack_trace; unsigned long stack_entries[MAX_STACK]; #endif }; /*----------------------------------------------------------------*/ #define dm_bufio_in_request() (!!current->bio_list) static void dm_bufio_lock(struct dm_bufio_client *c) { mutex_lock_nested(&c->lock, dm_bufio_in_request()); } static int dm_bufio_trylock(struct dm_bufio_client *c) { return mutex_trylock(&c->lock); } static void dm_bufio_unlock(struct dm_bufio_client *c) { mutex_unlock(&c->lock); } /*----------------------------------------------------------------*/ /* * Default cache size: available memory divided by the ratio. */ static unsigned long dm_bufio_default_cache_size; /* * Total cache size set by the user. */ static unsigned long dm_bufio_cache_size; /* * A copy of dm_bufio_cache_size because dm_bufio_cache_size can change * at any time. If it disagrees, the user has changed cache size. */ static unsigned long dm_bufio_cache_size_latch; static DEFINE_SPINLOCK(param_spinlock); /* * Buffers are freed after this timeout */ static unsigned dm_bufio_max_age = DM_BUFIO_DEFAULT_AGE_SECS; static unsigned long dm_bufio_retain_bytes = DM_BUFIO_DEFAULT_RETAIN_BYTES; static unsigned long dm_bufio_peak_allocated; static unsigned long dm_bufio_allocated_kmem_cache; static unsigned long dm_bufio_allocated_get_free_pages; static unsigned long dm_bufio_allocated_vmalloc; static unsigned long dm_bufio_current_allocated; /*----------------------------------------------------------------*/ /* * Per-client cache: dm_bufio_cache_size / dm_bufio_client_count */ static unsigned long dm_bufio_cache_size_per_client; /* * The current number of clients. */ static int dm_bufio_client_count; /* * The list of all clients. */ static LIST_HEAD(dm_bufio_all_clients); /* * This mutex protects dm_bufio_cache_size_latch, * dm_bufio_cache_size_per_client and dm_bufio_client_count */ static DEFINE_MUTEX(dm_bufio_clients_lock); #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING static void buffer_record_stack(struct dm_buffer *b) { b->stack_trace.nr_entries = 0; b->stack_trace.max_entries = MAX_STACK; b->stack_trace.entries = b->stack_entries; b->stack_trace.skip = 2; save_stack_trace(&b->stack_trace); } #endif /*---------------------------------------------------------------- * A red/black tree acts as an index for all the buffers. *--------------------------------------------------------------*/ static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block) { struct rb_node *n = c->buffer_tree.rb_node; struct dm_buffer *b; while (n) { b = container_of(n, struct dm_buffer, node); if (b->block == block) return b; n = (b->block < block) ? n->rb_left : n->rb_right; } return NULL; } static void __insert(struct dm_bufio_client *c, struct dm_buffer *b) { struct rb_node **new = &c->buffer_tree.rb_node, *parent = NULL; struct dm_buffer *found; while (*new) { found = container_of(*new, struct dm_buffer, node); if (found->block == b->block) { BUG_ON(found != b); return; } parent = *new; new = (found->block < b->block) ? &((*new)->rb_left) : &((*new)->rb_right); } rb_link_node(&b->node, parent, new); rb_insert_color(&b->node, &c->buffer_tree); } static void __remove(struct dm_bufio_client *c, struct dm_buffer *b) { rb_erase(&b->node, &c->buffer_tree); } /*----------------------------------------------------------------*/ static void adjust_total_allocated(unsigned char data_mode, long diff) { static unsigned long * const class_ptr[DATA_MODE_LIMIT] = { &dm_bufio_allocated_kmem_cache, &dm_bufio_allocated_get_free_pages, &dm_bufio_allocated_vmalloc, }; spin_lock(¶m_spinlock); *class_ptr[data_mode] += diff; dm_bufio_current_allocated += diff; if (dm_bufio_current_allocated > dm_bufio_peak_allocated) dm_bufio_peak_allocated = dm_bufio_current_allocated; spin_unlock(¶m_spinlock); } /* * Change the number of clients and recalculate per-client limit. */ static void __cache_size_refresh(void) { BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock)); BUG_ON(dm_bufio_client_count < 0); dm_bufio_cache_size_latch = READ_ONCE(dm_bufio_cache_size); /* * Use default if set to 0 and report the actual cache size used. */ if (!dm_bufio_cache_size_latch) { (void)cmpxchg(&dm_bufio_cache_size, 0, dm_bufio_default_cache_size); dm_bufio_cache_size_latch = dm_bufio_default_cache_size; } dm_bufio_cache_size_per_client = dm_bufio_cache_size_latch / (dm_bufio_client_count ? : 1); } /* * Allocating buffer data. * * Small buffers are allocated with kmem_cache, to use space optimally. * * For large buffers, we choose between get_free_pages and vmalloc. * Each has advantages and disadvantages. * * __get_free_pages can randomly fail if the memory is fragmented. * __vmalloc won't randomly fail, but vmalloc space is limited (it may be * as low as 128M) so using it for caching is not appropriate. * * If the allocation may fail we use __get_free_pages. Memory fragmentation * won't have a fatal effect here, but it just causes flushes of some other * buffers and more I/O will be performed. Don't use __get_free_pages if it * always fails (i.e. order >= MAX_ORDER). * * If the allocation shouldn't fail we use __vmalloc. This is only for the * initial reserve allocation, so there's no risk of wasting all vmalloc * space. */ static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask, unsigned char *data_mode) { if (unlikely(c->slab_cache != NULL)) { *data_mode = DATA_MODE_SLAB; return kmem_cache_alloc(c->slab_cache, gfp_mask); } if (c->block_size <= KMALLOC_MAX_SIZE && gfp_mask & __GFP_NORETRY) { *data_mode = DATA_MODE_GET_FREE_PAGES; return (void *)__get_free_pages(gfp_mask, c->sectors_per_block_bits - (PAGE_SHIFT - SECTOR_SHIFT)); } *data_mode = DATA_MODE_VMALLOC; /* * __vmalloc allocates the data pages and auxiliary structures with * gfp_flags that were specified, but pagetables are always allocated * with GFP_KERNEL, no matter what was specified as gfp_mask. * * Consequently, we must set per-process flag PF_MEMALLOC_NOIO so that * all allocations done by this process (including pagetables) are done * as if GFP_NOIO was specified. */ if (gfp_mask & __GFP_NORETRY) { unsigned noio_flag = memalloc_noio_save(); void *ptr = __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL); memalloc_noio_restore(noio_flag); return ptr; } return __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL); } /* * Free buffer's data. */ static void free_buffer_data(struct dm_bufio_client *c, void *data, unsigned char data_mode) { switch (data_mode) { case DATA_MODE_SLAB: kmem_cache_free(c->slab_cache, data); break; case DATA_MODE_GET_FREE_PAGES: free_pages((unsigned long)data, c->sectors_per_block_bits - (PAGE_SHIFT - SECTOR_SHIFT)); break; case DATA_MODE_VMALLOC: vfree(data); break; default: DMCRIT("dm_bufio_free_buffer_data: bad data mode: %d", data_mode); BUG(); } } /* * Allocate buffer and its data. */ static struct dm_buffer *alloc_buffer(struct dm_bufio_client *c, gfp_t gfp_mask) { struct dm_buffer *b = kmem_cache_alloc(c->slab_buffer, gfp_mask); if (!b) return NULL; b->c = c; b->data = alloc_buffer_data(c, gfp_mask, &b->data_mode); if (!b->data) { kmem_cache_free(c->slab_buffer, b); return NULL; } adjust_total_allocated(b->data_mode, (long)c->block_size); #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING memset(&b->stack_trace, 0, sizeof(b->stack_trace)); #endif return b; } /* * Free buffer and its data. */ static void free_buffer(struct dm_buffer *b) { struct dm_bufio_client *c = b->c; adjust_total_allocated(b->data_mode, -(long)c->block_size); free_buffer_data(c, b->data, b->data_mode); kmem_cache_free(c->slab_buffer, b); } /* * Link buffer to the buffer tree and clean or dirty queue. */ static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty) { struct dm_bufio_client *c = b->c; c->n_buffers[dirty]++; b->block = block; b->list_mode = dirty; list_add(&b->lru_list, &c->lru[dirty]); __insert(b->c, b); b->last_accessed = jiffies; } /* * Unlink buffer from the buffer tree and dirty or clean queue. */ static void __unlink_buffer(struct dm_buffer *b) { struct dm_bufio_client *c = b->c; BUG_ON(!c->n_buffers[b->list_mode]); c->n_buffers[b->list_mode]--; __remove(b->c, b); list_del(&b->lru_list); } /* * Place the buffer to the head of dirty or clean LRU queue. */ static void __relink_lru(struct dm_buffer *b, int dirty) { struct dm_bufio_client *c = b->c; BUG_ON(!c->n_buffers[b->list_mode]); c->n_buffers[b->list_mode]--; c->n_buffers[dirty]++; b->list_mode = dirty; list_move(&b->lru_list, &c->lru[dirty]); b->last_accessed = jiffies; } /*---------------------------------------------------------------- * Submit I/O on the buffer. * * Bio interface is faster but it has some problems: * the vector list is limited (increasing this limit increases * memory-consumption per buffer, so it is not viable); * * the memory must be direct-mapped, not vmalloced; * * If the buffer is small enough (up to DM_BUFIO_INLINE_VECS pages) and * it is not vmalloced, try using the bio interface. * * If the buffer is big, if it is vmalloced or if the underlying device * rejects the bio because it is too large, use dm-io layer to do the I/O. * The dm-io layer splits the I/O into multiple requests, avoiding the above * shortcomings. *--------------------------------------------------------------*/ /* * dm-io completion routine. It just calls b->bio.bi_end_io, pretending * that the request was handled directly with bio interface. */ static void dmio_complete(unsigned long error, void *context) { struct dm_buffer *b = context; b->end_io(b, unlikely(error != 0) ? BLK_STS_IOERR : 0); } static void use_dmio(struct dm_buffer *b, int rw, sector_t sector, unsigned n_sectors, unsigned offset) { int r; struct dm_io_request io_req = { .bi_op = rw, .bi_op_flags = 0, .notify.fn = dmio_complete, .notify.context = b, .client = b->c->dm_io, }; struct dm_io_region region = { .bdev = b->c->bdev, .sector = sector, .count = n_sectors, }; if (b->data_mode != DATA_MODE_VMALLOC) { io_req.mem.type = DM_IO_KMEM; io_req.mem.ptr.addr = (char *)b->data + offset; } else { io_req.mem.type = DM_IO_VMA; io_req.mem.ptr.vma = (char *)b->data + offset; } r = dm_io(&io_req, 1, ®ion, NULL); if (unlikely(r)) b->end_io(b, errno_to_blk_status(r)); } static void bio_complete(struct bio *bio) { struct dm_buffer *b = bio->bi_private; blk_status_t status = bio->bi_status; bio_put(bio); b->end_io(b, status); } static void use_bio(struct dm_buffer *b, int rw, sector_t sector, unsigned n_sectors, unsigned offset) { struct bio *bio; char *ptr; unsigned vec_size, len; vec_size = b->c->block_size >> PAGE_SHIFT; if (unlikely(b->c->sectors_per_block_bits < PAGE_SHIFT - SECTOR_SHIFT)) vec_size += 2; bio = bio_kmalloc(GFP_NOWAIT | __GFP_NORETRY | __GFP_NOWARN, vec_size); if (!bio) { dmio: use_dmio(b, rw, sector, n_sectors, offset); return; } bio->bi_iter.bi_sector = sector; bio_set_dev(bio, b->c->bdev); bio_set_op_attrs(bio, rw, 0); bio->bi_end_io = bio_complete; bio->bi_private = b; ptr = (char *)b->data + offset; len = n_sectors << SECTOR_SHIFT; do { unsigned this_step = min((unsigned)(PAGE_SIZE - offset_in_page(ptr)), len); if (!bio_add_page(bio, virt_to_page(ptr), this_step, offset_in_page(ptr))) { bio_put(bio); goto dmio; } len -= this_step; ptr += this_step; } while (len > 0); submit_bio(bio); } static void submit_io(struct dm_buffer *b, int rw, void (*end_io)(struct dm_buffer *, blk_status_t)) { unsigned n_sectors; sector_t sector; unsigned offset, end; b->end_io = end_io; if (likely(b->c->sectors_per_block_bits >= 0)) sector = b->block << b->c->sectors_per_block_bits; else sector = b->block * (b->c->block_size >> SECTOR_SHIFT); sector += b->c->start; if (rw != REQ_OP_WRITE) { n_sectors = b->c->block_size >> SECTOR_SHIFT; offset = 0; } else { if (b->c->write_callback) b->c->write_callback(b); offset = b->write_start; end = b->write_end; offset &= -DM_BUFIO_WRITE_ALIGN; end += DM_BUFIO_WRITE_ALIGN - 1; end &= -DM_BUFIO_WRITE_ALIGN; if (unlikely(end > b->c->block_size)) end = b->c->block_size; sector += offset >> SECTOR_SHIFT; n_sectors = (end - offset) >> SECTOR_SHIFT; } if (b->data_mode != DATA_MODE_VMALLOC) use_bio(b, rw, sector, n_sectors, offset); else use_dmio(b, rw, sector, n_sectors, offset); } /*---------------------------------------------------------------- * Writing dirty buffers *--------------------------------------------------------------*/ /* * The endio routine for write. * * Set the error, clear B_WRITING bit and wake anyone who was waiting on * it. */ static void write_endio(struct dm_buffer *b, blk_status_t status) { b->write_error = status; if (unlikely(status)) { struct dm_bufio_client *c = b->c; (void)cmpxchg(&c->async_write_error, 0, blk_status_to_errno(status)); } BUG_ON(!test_bit(B_WRITING, &b->state)); smp_mb__before_atomic(); clear_bit(B_WRITING, &b->state); smp_mb__after_atomic(); wake_up_bit(&b->state, B_WRITING); } /* * Initiate a write on a dirty buffer, but don't wait for it. * * - If the buffer is not dirty, exit. * - If there some previous write going on, wait for it to finish (we can't * have two writes on the same buffer simultaneously). * - Submit our write and don't wait on it. We set B_WRITING indicating * that there is a write in progress. */ static void __write_dirty_buffer(struct dm_buffer *b, struct list_head *write_list) { if (!test_bit(B_DIRTY, &b->state)) return; clear_bit(B_DIRTY, &b->state); wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); b->write_start = b->dirty_start; b->write_end = b->dirty_end; if (!write_list) submit_io(b, REQ_OP_WRITE, write_endio); else list_add_tail(&b->write_list, write_list); } static void __flush_write_list(struct list_head *write_list) { struct blk_plug plug; blk_start_plug(&plug); while (!list_empty(write_list)) { struct dm_buffer *b = list_entry(write_list->next, struct dm_buffer, write_list); list_del(&b->write_list); submit_io(b, REQ_OP_WRITE, write_endio); cond_resched(); } blk_finish_plug(&plug); } /* * Wait until any activity on the buffer finishes. Possibly write the * buffer if it is dirty. When this function finishes, there is no I/O * running on the buffer and the buffer is not dirty. */ static void __make_buffer_clean(struct dm_buffer *b) { BUG_ON(b->hold_count); if (!b->state) /* fast case */ return; wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE); __write_dirty_buffer(b, NULL); wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); } /* * Find some buffer that is not held by anybody, clean it, unlink it and * return it. */ static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c) { struct dm_buffer *b; list_for_each_entry_reverse(b, &c->lru[LIST_CLEAN], lru_list) { BUG_ON(test_bit(B_WRITING, &b->state)); BUG_ON(test_bit(B_DIRTY, &b->state)); if (!b->hold_count) { __make_buffer_clean(b); __unlink_buffer(b); return b; } cond_resched(); } list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) { BUG_ON(test_bit(B_READING, &b->state)); if (!b->hold_count) { __make_buffer_clean(b); __unlink_buffer(b); return b; } cond_resched(); } return NULL; } /* * Wait until some other threads free some buffer or release hold count on * some buffer. * * This function is entered with c->lock held, drops it and regains it * before exiting. */ static void __wait_for_free_buffer(struct dm_bufio_client *c) { DECLARE_WAITQUEUE(wait, current); add_wait_queue(&c->free_buffer_wait, &wait); set_current_state(TASK_UNINTERRUPTIBLE); dm_bufio_unlock(c); io_schedule(); remove_wait_queue(&c->free_buffer_wait, &wait); dm_bufio_lock(c); } enum new_flag { NF_FRESH = 0, NF_READ = 1, NF_GET = 2, NF_PREFETCH = 3 }; /* * Allocate a new buffer. If the allocation is not possible, wait until * some other thread frees a buffer. * * May drop the lock and regain it. */ static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf) { struct dm_buffer *b; bool tried_noio_alloc = false; /* * dm-bufio is resistant to allocation failures (it just keeps * one buffer reserved in cases all the allocations fail). * So set flags to not try too hard: * GFP_NOWAIT: don't wait; if we need to sleep we'll release our * mutex and wait ourselves. * __GFP_NORETRY: don't retry and rather return failure * __GFP_NOMEMALLOC: don't use emergency reserves * __GFP_NOWARN: don't print a warning in case of failure * * For debugging, if we set the cache size to 1, no new buffers will * be allocated. */ while (1) { if (dm_bufio_cache_size_latch != 1) { b = alloc_buffer(c, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); if (b) return b; } if (nf == NF_PREFETCH) return NULL; if (dm_bufio_cache_size_latch != 1 && !tried_noio_alloc) { dm_bufio_unlock(c); b = alloc_buffer(c, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); dm_bufio_lock(c); if (b) return b; tried_noio_alloc = true; } if (!list_empty(&c->reserved_buffers)) { b = list_entry(c->reserved_buffers.next, struct dm_buffer, lru_list); list_del(&b->lru_list); c->need_reserved_buffers++; return b; } b = __get_unclaimed_buffer(c); if (b) return b; __wait_for_free_buffer(c); } } static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c, enum new_flag nf) { struct dm_buffer *b = __alloc_buffer_wait_no_callback(c, nf); if (!b) return NULL; if (c->alloc_callback) c->alloc_callback(b); return b; } /* * Free a buffer and wake other threads waiting for free buffers. */ static void __free_buffer_wake(struct dm_buffer *b) { struct dm_bufio_client *c = b->c; if (!c->need_reserved_buffers) free_buffer(b); else { list_add(&b->lru_list, &c->reserved_buffers); c->need_reserved_buffers--; } wake_up(&c->free_buffer_wait); } static void __write_dirty_buffers_async(struct dm_bufio_client *c, int no_wait, struct list_head *write_list) { struct dm_buffer *b, *tmp; list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) { BUG_ON(test_bit(B_READING, &b->state)); if (!test_bit(B_DIRTY, &b->state) && !test_bit(B_WRITING, &b->state)) { __relink_lru(b, LIST_CLEAN); continue; } if (no_wait && test_bit(B_WRITING, &b->state)) return; __write_dirty_buffer(b, write_list); cond_resched(); } } /* * Get writeback threshold and buffer limit for a given client. */ static void __get_memory_limit(struct dm_bufio_client *c, unsigned long *threshold_buffers, unsigned long *limit_buffers) { unsigned long buffers; if (unlikely(READ_ONCE(dm_bufio_cache_size) != dm_bufio_cache_size_latch)) { if (mutex_trylock(&dm_bufio_clients_lock)) { __cache_size_refresh(); mutex_unlock(&dm_bufio_clients_lock); } } buffers = dm_bufio_cache_size_per_client; if (likely(c->sectors_per_block_bits >= 0)) buffers >>= c->sectors_per_block_bits + SECTOR_SHIFT; else buffers /= c->block_size; if (buffers < c->minimum_buffers) buffers = c->minimum_buffers; *limit_buffers = buffers; *threshold_buffers = mult_frac(buffers, DM_BUFIO_WRITEBACK_PERCENT, 100); } /* * Check if we're over watermark. * If we are over threshold_buffers, start freeing buffers. * If we're over "limit_buffers", block until we get under the limit. */ static void __check_watermark(struct dm_bufio_client *c, struct list_head *write_list) { unsigned long threshold_buffers, limit_buffers; __get_memory_limit(c, &threshold_buffers, &limit_buffers); while (c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY] > limit_buffers) { struct dm_buffer *b = __get_unclaimed_buffer(c); if (!b) return; __free_buffer_wake(b); cond_resched(); } if (c->n_buffers[LIST_DIRTY] > threshold_buffers) __write_dirty_buffers_async(c, 1, write_list); } /*---------------------------------------------------------------- * Getting a buffer *--------------------------------------------------------------*/ static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block, enum new_flag nf, int *need_submit, struct list_head *write_list) { struct dm_buffer *b, *new_b = NULL; *need_submit = 0; b = __find(c, block); if (b) goto found_buffer; if (nf == NF_GET) return NULL; new_b = __alloc_buffer_wait(c, nf); if (!new_b) return NULL; /* * We've had a period where the mutex was unlocked, so need to * recheck the buffer tree. */ b = __find(c, block); if (b) { __free_buffer_wake(new_b); goto found_buffer; } __check_watermark(c, write_list); b = new_b; b->hold_count = 1; b->read_error = 0; b->write_error = 0; __link_buffer(b, block, LIST_CLEAN); if (nf == NF_FRESH) { b->state = 0; return b; } b->state = 1 << B_READING; *need_submit = 1; return b; found_buffer: if (nf == NF_PREFETCH) return NULL; /* * Note: it is essential that we don't wait for the buffer to be * read if dm_bufio_get function is used. Both dm_bufio_get and * dm_bufio_prefetch can be used in the driver request routine. * If the user called both dm_bufio_prefetch and dm_bufio_get on * the same buffer, it would deadlock if we waited. */ if (nf == NF_GET && unlikely(test_bit(B_READING, &b->state))) return NULL; b->hold_count++; __relink_lru(b, test_bit(B_DIRTY, &b->state) || test_bit(B_WRITING, &b->state)); return b; } /* * The endio routine for reading: set the error, clear the bit and wake up * anyone waiting on the buffer. */ static void read_endio(struct dm_buffer *b, blk_status_t status) { b->read_error = status; BUG_ON(!test_bit(B_READING, &b->state)); smp_mb__before_atomic(); clear_bit(B_READING, &b->state); smp_mb__after_atomic(); wake_up_bit(&b->state, B_READING); } /* * A common routine for dm_bufio_new and dm_bufio_read. Operation of these * functions is similar except that dm_bufio_new doesn't read the * buffer from the disk (assuming that the caller overwrites all the data * and uses dm_bufio_mark_buffer_dirty to write new data back). */ static void *new_read(struct dm_bufio_client *c, sector_t block, enum new_flag nf, struct dm_buffer **bp) { int need_submit; struct dm_buffer *b; LIST_HEAD(write_list); dm_bufio_lock(c); b = __bufio_new(c, block, nf, &need_submit, &write_list); #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING if (b && b->hold_count == 1) buffer_record_stack(b); #endif dm_bufio_unlock(c); __flush_write_list(&write_list); if (!b) return NULL; if (need_submit) submit_io(b, REQ_OP_READ, read_endio); wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE); if (b->read_error) { int error = blk_status_to_errno(b->read_error); dm_bufio_release(b); return ERR_PTR(error); } *bp = b; return b->data; } void *dm_bufio_get(struct dm_bufio_client *c, sector_t block, struct dm_buffer **bp) { return new_read(c, block, NF_GET, bp); } EXPORT_SYMBOL_GPL(dm_bufio_get); void *dm_bufio_read(struct dm_bufio_client *c, sector_t block, struct dm_buffer **bp) { BUG_ON(dm_bufio_in_request()); return new_read(c, block, NF_READ, bp); } EXPORT_SYMBOL_GPL(dm_bufio_read); void *dm_bufio_new(struct dm_bufio_client *c, sector_t block, struct dm_buffer **bp) { BUG_ON(dm_bufio_in_request()); return new_read(c, block, NF_FRESH, bp); } EXPORT_SYMBOL_GPL(dm_bufio_new); void dm_bufio_prefetch(struct dm_bufio_client *c, sector_t block, unsigned n_blocks) { struct blk_plug plug; LIST_HEAD(write_list); BUG_ON(dm_bufio_in_request()); blk_start_plug(&plug); dm_bufio_lock(c); for (; n_blocks--; block++) { int need_submit; struct dm_buffer *b; b = __bufio_new(c, block, NF_PREFETCH, &need_submit, &write_list); if (unlikely(!list_empty(&write_list))) { dm_bufio_unlock(c); blk_finish_plug(&plug); __flush_write_list(&write_list); blk_start_plug(&plug); dm_bufio_lock(c); } if (unlikely(b != NULL)) { dm_bufio_unlock(c); if (need_submit) submit_io(b, REQ_OP_READ, read_endio); dm_bufio_release(b); cond_resched(); if (!n_blocks) goto flush_plug; dm_bufio_lock(c); } } dm_bufio_unlock(c); flush_plug: blk_finish_plug(&plug); } EXPORT_SYMBOL_GPL(dm_bufio_prefetch); void dm_bufio_release(struct dm_buffer *b) { struct dm_bufio_client *c = b->c; dm_bufio_lock(c); BUG_ON(!b->hold_count); b->hold_count--; if (!b->hold_count) { wake_up(&c->free_buffer_wait); /* * If there were errors on the buffer, and the buffer is not * to be written, free the buffer. There is no point in caching * invalid buffer. */ if ((b->read_error || b->write_error) && !test_bit(B_READING, &b->state) && !test_bit(B_WRITING, &b->state) && !test_bit(B_DIRTY, &b->state)) { __unlink_buffer(b); __free_buffer_wake(b); } } dm_bufio_unlock(c); } EXPORT_SYMBOL_GPL(dm_bufio_release); void dm_bufio_mark_partial_buffer_dirty(struct dm_buffer *b, unsigned start, unsigned end) { struct dm_bufio_client *c = b->c; BUG_ON(start >= end); BUG_ON(end > b->c->block_size); dm_bufio_lock(c); BUG_ON(test_bit(B_READING, &b->state)); if (!test_and_set_bit(B_DIRTY, &b->state)) { b->dirty_start = start; b->dirty_end = end; __relink_lru(b, LIST_DIRTY); } else { if (start < b->dirty_start) b->dirty_start = start; if (end > b->dirty_end) b->dirty_end = end; } dm_bufio_unlock(c); } EXPORT_SYMBOL_GPL(dm_bufio_mark_partial_buffer_dirty); void dm_bufio_mark_buffer_dirty(struct dm_buffer *b) { dm_bufio_mark_partial_buffer_dirty(b, 0, b->c->block_size); } EXPORT_SYMBOL_GPL(dm_bufio_mark_buffer_dirty); void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c) { LIST_HEAD(write_list); BUG_ON(dm_bufio_in_request()); dm_bufio_lock(c); __write_dirty_buffers_async(c, 0, &write_list); dm_bufio_unlock(c); __flush_write_list(&write_list); } EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers_async); /* * For performance, it is essential that the buffers are written asynchronously * and simultaneously (so that the block layer can merge the writes) and then * waited upon. * * Finally, we flush hardware disk cache. */ int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c) { int a, f; unsigned long buffers_processed = 0; struct dm_buffer *b, *tmp; LIST_HEAD(write_list); dm_bufio_lock(c); __write_dirty_buffers_async(c, 0, &write_list); dm_bufio_unlock(c); __flush_write_list(&write_list); dm_bufio_lock(c); again: list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_DIRTY], lru_list) { int dropped_lock = 0; if (buffers_processed < c->n_buffers[LIST_DIRTY]) buffers_processed++; BUG_ON(test_bit(B_READING, &b->state)); if (test_bit(B_WRITING, &b->state)) { if (buffers_processed < c->n_buffers[LIST_DIRTY]) { dropped_lock = 1; b->hold_count++; dm_bufio_unlock(c); wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); dm_bufio_lock(c); b->hold_count--; } else wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); } if (!test_bit(B_DIRTY, &b->state) && !test_bit(B_WRITING, &b->state)) __relink_lru(b, LIST_CLEAN); cond_resched(); /* * If we dropped the lock, the list is no longer consistent, * so we must restart the search. * * In the most common case, the buffer just processed is * relinked to the clean list, so we won't loop scanning the * same buffer again and again. * * This may livelock if there is another thread simultaneously * dirtying buffers, so we count the number of buffers walked * and if it exceeds the total number of buffers, it means that * someone is doing some writes simultaneously with us. In * this case, stop, dropping the lock. */ if (dropped_lock) goto again; } wake_up(&c->free_buffer_wait); dm_bufio_unlock(c); a = xchg(&c->async_write_error, 0); f = dm_bufio_issue_flush(c); if (a) return a; return f; } EXPORT_SYMBOL_GPL(dm_bufio_write_dirty_buffers); /* * Use dm-io to send an empty barrier to flush the device. */ int dm_bufio_issue_flush(struct dm_bufio_client *c) { struct dm_io_request io_req = { .bi_op = REQ_OP_WRITE, .bi_op_flags = REQ_PREFLUSH | REQ_SYNC, .mem.type = DM_IO_KMEM, .mem.ptr.addr = NULL, .client = c->dm_io, }; struct dm_io_region io_reg = { .bdev = c->bdev, .sector = 0, .count = 0, }; BUG_ON(dm_bufio_in_request()); return dm_io(&io_req, 1, &io_reg, NULL); } EXPORT_SYMBOL_GPL(dm_bufio_issue_flush); /* * We first delete any other buffer that may be at that new location. * * Then, we write the buffer to the original location if it was dirty. * * Then, if we are the only one who is holding the buffer, relink the buffer * in the buffer tree for the new location. * * If there was someone else holding the buffer, we write it to the new * location but not relink it, because that other user needs to have the buffer * at the same place. */ void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block) { struct dm_bufio_client *c = b->c; struct dm_buffer *new; BUG_ON(dm_bufio_in_request()); dm_bufio_lock(c); retry: new = __find(c, new_block); if (new) { if (new->hold_count) { __wait_for_free_buffer(c); goto retry; } /* * FIXME: Is there any point waiting for a write that's going * to be overwritten in a bit? */ __make_buffer_clean(new); __unlink_buffer(new); __free_buffer_wake(new); } BUG_ON(!b->hold_count); BUG_ON(test_bit(B_READING, &b->state)); __write_dirty_buffer(b, NULL); if (b->hold_count == 1) { wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); set_bit(B_DIRTY, &b->state); b->dirty_start = 0; b->dirty_end = c->block_size; __unlink_buffer(b); __link_buffer(b, new_block, LIST_DIRTY); } else { sector_t old_block; wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); /* * Relink buffer to "new_block" so that write_callback * sees "new_block" as a block number. * After the write, link the buffer back to old_block. * All this must be done in bufio lock, so that block number * change isn't visible to other threads. */ old_block = b->block; __unlink_buffer(b); __link_buffer(b, new_block, b->list_mode); submit_io(b, REQ_OP_WRITE, write_endio); wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE); __unlink_buffer(b); __link_buffer(b, old_block, b->list_mode); } dm_bufio_unlock(c); dm_bufio_release(b); } EXPORT_SYMBOL_GPL(dm_bufio_release_move); /* * Free the given buffer. * * This is just a hint, if the buffer is in use or dirty, this function * does nothing. */ void dm_bufio_forget(struct dm_bufio_client *c, sector_t block) { struct dm_buffer *b; dm_bufio_lock(c); b = __find(c, block); if (b && likely(!b->hold_count) && likely(!b->state)) { __unlink_buffer(b); __free_buffer_wake(b); } dm_bufio_unlock(c); } EXPORT_SYMBOL_GPL(dm_bufio_forget); void dm_bufio_set_minimum_buffers(struct dm_bufio_client *c, unsigned n) { c->minimum_buffers = n; } EXPORT_SYMBOL_GPL(dm_bufio_set_minimum_buffers); unsigned dm_bufio_get_block_size(struct dm_bufio_client *c) { return c->block_size; } EXPORT_SYMBOL_GPL(dm_bufio_get_block_size); sector_t dm_bufio_get_device_size(struct dm_bufio_client *c) { sector_t s = i_size_read(c->bdev->bd_inode) >> SECTOR_SHIFT; if (likely(c->sectors_per_block_bits >= 0)) s >>= c->sectors_per_block_bits; else sector_div(s, c->block_size >> SECTOR_SHIFT); return s; } EXPORT_SYMBOL_GPL(dm_bufio_get_device_size); sector_t dm_bufio_get_block_number(struct dm_buffer *b) { return b->block; } EXPORT_SYMBOL_GPL(dm_bufio_get_block_number); void *dm_bufio_get_block_data(struct dm_buffer *b) { return b->data; } EXPORT_SYMBOL_GPL(dm_bufio_get_block_data); void *dm_bufio_get_aux_data(struct dm_buffer *b) { return b + 1; } EXPORT_SYMBOL_GPL(dm_bufio_get_aux_data); struct dm_bufio_client *dm_bufio_get_client(struct dm_buffer *b) { return b->c; } EXPORT_SYMBOL_GPL(dm_bufio_get_client); static void drop_buffers(struct dm_bufio_client *c) { struct dm_buffer *b; int i; bool warned = false; BUG_ON(dm_bufio_in_request()); /* * An optimization so that the buffers are not written one-by-one. */ dm_bufio_write_dirty_buffers_async(c); dm_bufio_lock(c); while ((b = __get_unclaimed_buffer(c))) __free_buffer_wake(b); for (i = 0; i < LIST_SIZE; i++) list_for_each_entry(b, &c->lru[i], lru_list) { WARN_ON(!warned); warned = true; DMERR("leaked buffer %llx, hold count %u, list %d", (unsigned long long)b->block, b->hold_count, i); #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING print_stack_trace(&b->stack_trace, 1); b->hold_count = 0; /* mark unclaimed to avoid BUG_ON below */ #endif } #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING while ((b = __get_unclaimed_buffer(c))) __free_buffer_wake(b); #endif for (i = 0; i < LIST_SIZE; i++) BUG_ON(!list_empty(&c->lru[i])); dm_bufio_unlock(c); } /* * We may not be able to evict this buffer if IO pending or the client * is still using it. Caller is expected to know buffer is too old. * * And if GFP_NOFS is used, we must not do any I/O because we hold * dm_bufio_clients_lock and we would risk deadlock if the I/O gets * rerouted to different bufio client. */ static bool __try_evict_buffer(struct dm_buffer *b, gfp_t gfp) { if (!(gfp & __GFP_FS)) { if (test_bit(B_READING, &b->state) || test_bit(B_WRITING, &b->state) || test_bit(B_DIRTY, &b->state)) return false; } if (b->hold_count) return false; __make_buffer_clean(b); __unlink_buffer(b); __free_buffer_wake(b); return true; } static unsigned long get_retain_buffers(struct dm_bufio_client *c) { unsigned long retain_bytes = READ_ONCE(dm_bufio_retain_bytes); if (likely(c->sectors_per_block_bits >= 0)) retain_bytes >>= c->sectors_per_block_bits + SECTOR_SHIFT; else retain_bytes /= c->block_size; return retain_bytes; } static unsigned long __scan(struct dm_bufio_client *c, unsigned long nr_to_scan, gfp_t gfp_mask) { int l; struct dm_buffer *b, *tmp; unsigned long freed = 0; unsigned long count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY]; unsigned long retain_target = get_retain_buffers(c); for (l = 0; l < LIST_SIZE; l++) { list_for_each_entry_safe_reverse(b, tmp, &c->lru[l], lru_list) { if (__try_evict_buffer(b, gfp_mask)) freed++; if (!--nr_to_scan || ((count - freed) <= retain_target)) return freed; cond_resched(); } } return freed; } static unsigned long dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) { struct dm_bufio_client *c; unsigned long freed; c = container_of(shrink, struct dm_bufio_client, shrinker); if (sc->gfp_mask & __GFP_FS) dm_bufio_lock(c); else if (!dm_bufio_trylock(c)) return SHRINK_STOP; freed = __scan(c, sc->nr_to_scan, sc->gfp_mask); dm_bufio_unlock(c); return freed; } static unsigned long dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc) { struct dm_bufio_client *c = container_of(shrink, struct dm_bufio_client, shrinker); unsigned long count = READ_ONCE(c->n_buffers[LIST_CLEAN]) + READ_ONCE(c->n_buffers[LIST_DIRTY]); unsigned long retain_target = get_retain_buffers(c); return (count < retain_target) ? 0 : (count - retain_target); } /* * Create the buffering interface */ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsigned block_size, unsigned reserved_buffers, unsigned aux_size, void (*alloc_callback)(struct dm_buffer *), void (*write_callback)(struct dm_buffer *)) { int r; struct dm_bufio_client *c; unsigned i; char slab_name[27]; if (!block_size || block_size & ((1 << SECTOR_SHIFT) - 1)) { DMERR("%s: block size not specified or is not multiple of 512b", __func__); r = -EINVAL; goto bad_client; } c = kzalloc(sizeof(*c), GFP_KERNEL); if (!c) { r = -ENOMEM; goto bad_client; } c->buffer_tree = RB_ROOT; c->bdev = bdev; c->block_size = block_size; if (is_power_of_2(block_size)) c->sectors_per_block_bits = __ffs(block_size) - SECTOR_SHIFT; else c->sectors_per_block_bits = -1; c->alloc_callback = alloc_callback; c->write_callback = write_callback; for (i = 0; i < LIST_SIZE; i++) { INIT_LIST_HEAD(&c->lru[i]); c->n_buffers[i] = 0; } mutex_init(&c->lock); INIT_LIST_HEAD(&c->reserved_buffers); c->need_reserved_buffers = reserved_buffers; dm_bufio_set_minimum_buffers(c, DM_BUFIO_MIN_BUFFERS); init_waitqueue_head(&c->free_buffer_wait); c->async_write_error = 0; c->dm_io = dm_io_client_create(); if (IS_ERR(c->dm_io)) { r = PTR_ERR(c->dm_io); goto bad_dm_io; } if (block_size <= KMALLOC_MAX_SIZE && (block_size < PAGE_SIZE || !is_power_of_2(block_size))) { unsigned align = min(1U << __ffs(block_size), (unsigned)PAGE_SIZE); snprintf(slab_name, sizeof slab_name, "dm_bufio_cache-%u", block_size); c->slab_cache = kmem_cache_create(slab_name, block_size, align, SLAB_RECLAIM_ACCOUNT, NULL); if (!c->slab_cache) { r = -ENOMEM; goto bad; } } if (aux_size) snprintf(slab_name, sizeof slab_name, "dm_bufio_buffer-%u", aux_size); else snprintf(slab_name, sizeof slab_name, "dm_bufio_buffer"); c->slab_buffer = kmem_cache_create(slab_name, sizeof(struct dm_buffer) + aux_size, 0, SLAB_RECLAIM_ACCOUNT, NULL); if (!c->slab_buffer) { r = -ENOMEM; goto bad; } while (c->need_reserved_buffers) { struct dm_buffer *b = alloc_buffer(c, GFP_KERNEL); if (!b) { r = -ENOMEM; goto bad; } __free_buffer_wake(b); } c->shrinker.count_objects = dm_bufio_shrink_count; c->shrinker.scan_objects = dm_bufio_shrink_scan; c->shrinker.seeks = 1; c->shrinker.batch = 0; r = register_shrinker(&c->shrinker); if (r) goto bad; mutex_lock(&dm_bufio_clients_lock); dm_bufio_client_count++; list_add(&c->client_list, &dm_bufio_all_clients); __cache_size_refresh(); mutex_unlock(&dm_bufio_clients_lock); return c; bad: while (!list_empty(&c->reserved_buffers)) { struct dm_buffer *b = list_entry(c->reserved_buffers.next, struct dm_buffer, lru_list); list_del(&b->lru_list); free_buffer(b); } kmem_cache_destroy(c->slab_cache); kmem_cache_destroy(c->slab_buffer); dm_io_client_destroy(c->dm_io); bad_dm_io: mutex_destroy(&c->lock); kfree(c); bad_client: return ERR_PTR(r); } EXPORT_SYMBOL_GPL(dm_bufio_client_create); /* * Free the buffering interface. * It is required that there are no references on any buffers. */ void dm_bufio_client_destroy(struct dm_bufio_client *c) { unsigned i; drop_buffers(c); unregister_shrinker(&c->shrinker); mutex_lock(&dm_bufio_clients_lock); list_del(&c->client_list); dm_bufio_client_count--; __cache_size_refresh(); mutex_unlock(&dm_bufio_clients_lock); BUG_ON(!RB_EMPTY_ROOT(&c->buffer_tree)); BUG_ON(c->need_reserved_buffers); while (!list_empty(&c->reserved_buffers)) { struct dm_buffer *b = list_entry(c->reserved_buffers.next, struct dm_buffer, lru_list); list_del(&b->lru_list); free_buffer(b); } for (i = 0; i < LIST_SIZE; i++) if (c->n_buffers[i]) DMERR("leaked buffer count %d: %ld", i, c->n_buffers[i]); for (i = 0; i < LIST_SIZE; i++) BUG_ON(c->n_buffers[i]); kmem_cache_destroy(c->slab_cache); kmem_cache_destroy(c->slab_buffer); dm_io_client_destroy(c->dm_io); mutex_destroy(&c->lock); kfree(c); } EXPORT_SYMBOL_GPL(dm_bufio_client_destroy); void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start) { c->start = start; } EXPORT_SYMBOL_GPL(dm_bufio_set_sector_offset); static unsigned get_max_age_hz(void) { unsigned max_age = READ_ONCE(dm_bufio_max_age); if (max_age > UINT_MAX / HZ) max_age = UINT_MAX / HZ; return max_age * HZ; } static bool older_than(struct dm_buffer *b, unsigned long age_hz) { return time_after_eq(jiffies, b->last_accessed + age_hz); } static void __evict_old_buffers(struct dm_bufio_client *c, unsigned long age_hz) { struct dm_buffer *b, *tmp; unsigned long retain_target = get_retain_buffers(c); unsigned long count; LIST_HEAD(write_list); dm_bufio_lock(c); __check_watermark(c, &write_list); if (unlikely(!list_empty(&write_list))) { dm_bufio_unlock(c); __flush_write_list(&write_list); dm_bufio_lock(c); } count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY]; list_for_each_entry_safe_reverse(b, tmp, &c->lru[LIST_CLEAN], lru_list) { if (count <= retain_target) break; if (!older_than(b, age_hz)) break; if (__try_evict_buffer(b, 0)) count--; cond_resched(); } dm_bufio_unlock(c); } static void cleanup_old_buffers(void) { unsigned long max_age_hz = get_max_age_hz(); struct dm_bufio_client *c; mutex_lock(&dm_bufio_clients_lock); __cache_size_refresh(); list_for_each_entry(c, &dm_bufio_all_clients, client_list) __evict_old_buffers(c, max_age_hz); mutex_unlock(&dm_bufio_clients_lock); } static struct workqueue_struct *dm_bufio_wq; static struct delayed_work dm_bufio_work; static void work_fn(struct work_struct *w) { cleanup_old_buffers(); queue_delayed_work(dm_bufio_wq, &dm_bufio_work, DM_BUFIO_WORK_TIMER_SECS * HZ); } /*---------------------------------------------------------------- * Module setup *--------------------------------------------------------------*/ /* * This is called only once for the whole dm_bufio module. * It initializes memory limit. */ static int __init dm_bufio_init(void) { __u64 mem; dm_bufio_allocated_kmem_cache = 0; dm_bufio_allocated_get_free_pages = 0; dm_bufio_allocated_vmalloc = 0; dm_bufio_current_allocated = 0; mem = (__u64)mult_frac(totalram_pages() - totalhigh_pages(), DM_BUFIO_MEMORY_PERCENT, 100) << PAGE_SHIFT; if (mem > ULONG_MAX) mem = ULONG_MAX; #ifdef CONFIG_MMU if (mem > mult_frac(VMALLOC_TOTAL, DM_BUFIO_VMALLOC_PERCENT, 100)) mem = mult_frac(VMALLOC_TOTAL, DM_BUFIO_VMALLOC_PERCENT, 100); #endif dm_bufio_default_cache_size = mem; mutex_lock(&dm_bufio_clients_lock); __cache_size_refresh(); mutex_unlock(&dm_bufio_clients_lock); dm_bufio_wq = alloc_workqueue("dm_bufio_cache", WQ_MEM_RECLAIM, 0); if (!dm_bufio_wq) return -ENOMEM; INIT_DELAYED_WORK(&dm_bufio_work, work_fn); queue_delayed_work(dm_bufio_wq, &dm_bufio_work, DM_BUFIO_WORK_TIMER_SECS * HZ); return 0; } /* * This is called once when unloading the dm_bufio module. */ static void __exit dm_bufio_exit(void) { int bug = 0; cancel_delayed_work_sync(&dm_bufio_work); destroy_workqueue(dm_bufio_wq); if (dm_bufio_client_count) { DMCRIT("%s: dm_bufio_client_count leaked: %d", __func__, dm_bufio_client_count); bug = 1; } if (dm_bufio_current_allocated) { DMCRIT("%s: dm_bufio_current_allocated leaked: %lu", __func__, dm_bufio_current_allocated); bug = 1; } if (dm_bufio_allocated_get_free_pages) { DMCRIT("%s: dm_bufio_allocated_get_free_pages leaked: %lu", __func__, dm_bufio_allocated_get_free_pages); bug = 1; } if (dm_bufio_allocated_vmalloc) { DMCRIT("%s: dm_bufio_vmalloc leaked: %lu", __func__, dm_bufio_allocated_vmalloc); bug = 1; } BUG_ON(bug); } module_init(dm_bufio_init) module_exit(dm_bufio_exit) module_param_named(max_cache_size_bytes, dm_bufio_cache_size, ulong, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(max_cache_size_bytes, "Size of metadata cache"); module_param_named(max_age_seconds, dm_bufio_max_age, uint, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(max_age_seconds, "Max age of a buffer in seconds"); module_param_named(retain_bytes, dm_bufio_retain_bytes, ulong, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(retain_bytes, "Try to keep at least this many bytes cached in memory"); module_param_named(peak_allocated_bytes, dm_bufio_peak_allocated, ulong, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(peak_allocated_bytes, "Tracks the maximum allocated memory"); module_param_named(allocated_kmem_cache_bytes, dm_bufio_allocated_kmem_cache, ulong, S_IRUGO); MODULE_PARM_DESC(allocated_kmem_cache_bytes, "Memory allocated with kmem_cache_alloc"); module_param_named(allocated_get_free_pages_bytes, dm_bufio_allocated_get_free_pages, ulong, S_IRUGO); MODULE_PARM_DESC(allocated_get_free_pages_bytes, "Memory allocated with get_free_pages"); module_param_named(allocated_vmalloc_bytes, dm_bufio_allocated_vmalloc, ulong, S_IRUGO); MODULE_PARM_DESC(allocated_vmalloc_bytes, "Memory allocated with vmalloc"); module_param_named(current_allocated_bytes, dm_bufio_current_allocated, ulong, S_IRUGO); MODULE_PARM_DESC(current_allocated_bytes, "Memory currently used by the cache"); MODULE_AUTHOR("Mikulas Patocka <dm-devel@redhat.com>"); MODULE_DESCRIPTION(DM_NAME " buffered I/O library"); MODULE_LICENSE("GPL");
Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.
Created with Cregit http://github.com/cregit/cregit
Version 2.0-RC1