| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Ming Lei | 1651 | 16.83% | 16 | 4.75% |
| Christoph Hellwig | 956 | 9.74% | 48 | 14.24% |
| Dan Schatzberg | 893 | 9.10% | 2 | 0.59% |
| Linus Torvalds (pre-git) | 722 | 7.36% | 46 | 13.65% |
| Andries E. Brouwer | 588 | 5.99% | 5 | 1.48% |
| Martijn Coenen | 471 | 4.80% | 15 | 4.45% |
| Jan Kara | 433 | 4.41% | 16 | 4.75% |
| Kay Sievers | 400 | 4.08% | 5 | 1.48% |
| Tetsuo Handa | 352 | 3.59% | 10 | 2.97% |
| David Howells | 307 | 3.13% | 2 | 0.59% |
| Omar Sandoval | 279 | 2.84% | 7 | 2.08% |
| Andrew Morton | 230 | 2.34% | 19 | 5.64% |
| Shaohua Li | 215 | 2.19% | 6 | 1.78% |
| Theodore Y. Ts'o | 183 | 1.87% | 2 | 0.59% |
| Milan Broz | 173 | 1.76% | 3 | 0.89% |
| Al Viro | 156 | 1.59% | 19 | 5.64% |
| Kenneth W Chen | 150 | 1.53% | 2 | 0.59% |
| Linus Torvalds | 148 | 1.51% | 11 | 3.26% |
| Jens Axboe | 142 | 1.45% | 9 | 2.67% |
| Lukas Czerner | 137 | 1.40% | 3 | 0.89% |
| Pavel Tatashin | 106 | 1.08% | 1 | 0.30% |
| Anton Altaparmakov | 100 | 1.02% | 1 | 0.30% |
| Chaitanya Kulkarni | 91 | 0.93% | 4 | 1.19% |
| Bart Van Assche | 73 | 0.74% | 5 | 1.48% |
| Dmitriy Monakhov | 73 | 0.74% | 1 | 0.30% |
| Jaegeuk Kim | 61 | 0.62% | 1 | 0.30% |
| Guo Chao | 45 | 0.46% | 3 | 0.89% |
| Matteo Croce | 39 | 0.40% | 1 | 0.30% |
| Evan Green | 36 | 0.37% | 3 | 0.89% |
| Darrick J. Wong | 36 | 0.37% | 1 | 0.30% |
| Holger Hoffstätte | 35 | 0.36% | 1 | 0.30% |
| Laurent Vivier | 34 | 0.35% | 1 | 0.30% |
| Dongli Zhang | 33 | 0.34% | 3 | 0.89% |
| Petr Vorel | 32 | 0.33% | 1 | 0.30% |
| Namhyung Kim | 30 | 0.31% | 3 | 0.89% |
| Junjiro R. Okajima | 25 | 0.25% | 1 | 0.30% |
| Nikanth Karthikesan | 25 | 0.25% | 2 | 0.59% |
| Mauricio Faria de Oliveira | 23 | 0.23% | 1 | 0.30% |
| Tejun Heo | 21 | 0.21% | 1 | 0.30% |
| Mikulas Patocka | 20 | 0.20% | 2 | 0.59% |
| Zhong Jinghua | 19 | 0.19% | 1 | 0.30% |
| Michael Christie | 19 | 0.19% | 3 | 0.89% |
| Luis R. Rodriguez | 19 | 0.19% | 2 | 0.59% |
| Neil Brown | 19 | 0.19% | 3 | 0.89% |
| David Woodhouse | 18 | 0.18% | 1 | 0.30% |
| David Zeuthen | 18 | 0.18% | 1 | 0.30% |
| Adam Manzanares | 16 | 0.16% | 1 | 0.30% |
| Alyssa Ross | 12 | 0.12% | 1 | 0.30% |
| Ira Weiny | 12 | 0.12% | 1 | 0.30% |
| Serge E. Hallyn | 11 | 0.11% | 1 | 0.30% |
| Lennart Poettering | 9 | 0.09% | 1 | 0.30% |
| Kent Overstreet | 9 | 0.09% | 1 | 0.30% |
| Anton Volkov | 7 | 0.07% | 1 | 0.30% |
| Miklos Szeredi | 7 | 0.07% | 2 | 0.59% |
| Rusty Russell | 6 | 0.06% | 1 | 0.30% |
| Stephen Hemminger | 6 | 0.06% | 1 | 0.30% |
| Dave Young | 6 | 0.06% | 1 | 0.30% |
| Arnd Bergmann | 6 | 0.06% | 3 | 0.89% |
| Xie Yongji | 5 | 0.05% | 3 | 0.89% |
| Kristian Klausen | 5 | 0.05% | 1 | 0.30% |
| Silva Paulo | 5 | 0.05% | 1 | 0.30% |
| Carlos Llamas | 4 | 0.04% | 1 | 0.30% |
| Lei Ming | 4 | 0.04% | 1 | 0.30% |
| Gustavo A. R. Silva | 4 | 0.04% | 1 | 0.30% |
| Isaac Manjarres | 4 | 0.04% | 1 | 0.30% |
| Nicholas Piggin | 4 | 0.04% | 1 | 0.30% |
| Franz Pletz | 4 | 0.04% | 1 | 0.30% |
| Alessio Balsini | 3 | 0.03% | 1 | 0.30% |
| Pavel Machek | 3 | 0.03% | 1 | 0.30% |
| Ingo Molnar | 3 | 0.03% | 1 | 0.30% |
| Joe Perches | 3 | 0.03% | 1 | 0.30% |
| zhengbin | 2 | 0.02% | 1 | 0.30% |
| Phillip Susi | 2 | 0.02% | 1 | 0.30% |
| Kees Cook | 2 | 0.02% | 1 | 0.30% |
| Adrian Bunk | 2 | 0.02% | 1 | 0.30% |
| Dennis Zhou | 2 | 0.02% | 1 | 0.30% |
| Alexey Dobriyan | 1 | 0.01% | 1 | 0.30% |
| Mike Galbraith | 1 | 0.01% | 1 | 0.30% |
| Greg Kroah-Hartman | 1 | 0.01% | 1 | 0.30% |
| Chengguang Xu | 1 | 0.01% | 1 | 0.30% |
| Steven Rostedt | 1 | 0.01% | 1 | 0.30% |
| Alexander Beregalov | 1 | 0.01% | 1 | 0.30% |
| David Chinner | 1 | 0.01% | 1 | 0.30% |
| Eric Biggers | 1 | 0.01% | 1 | 0.30% |
| Total | 9812 | 337 |
// SPDX-License-Identifier: GPL-2.0-only /* * Copyright 1993 by Theodore Ts'o. */ #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/sched.h> #include <linux/fs.h> #include <linux/pagemap.h> #include <linux/file.h> #include <linux/stat.h> #include <linux/errno.h> #include <linux/major.h> #include <linux/wait.h> #include <linux/blkpg.h> #include <linux/init.h> #include <linux/swap.h> #include <linux/slab.h> #include <linux/compat.h> #include <linux/suspend.h> #include <linux/freezer.h> #include <linux/mutex.h> #include <linux/writeback.h> #include <linux/completion.h> #include <linux/highmem.h> #include <linux/splice.h> #include <linux/sysfs.h> #include <linux/miscdevice.h> #include <linux/falloc.h> #include <linux/uio.h> #include <linux/ioprio.h> #include <linux/blk-cgroup.h> #include <linux/sched/mm.h> #include <linux/statfs.h> #include <linux/uaccess.h> #include <linux/blk-mq.h> #include <linux/spinlock.h> #include <uapi/linux/loop.h> /* Possible states of device */ enum { Lo_unbound, Lo_bound, Lo_rundown, Lo_deleting, }; struct loop_func_table; struct loop_device { int lo_number; loff_t lo_offset; loff_t lo_sizelimit; int lo_flags; char lo_file_name[LO_NAME_SIZE]; struct file * lo_backing_file; struct block_device *lo_device; gfp_t old_gfp_mask; spinlock_t lo_lock; int lo_state; spinlock_t lo_work_lock; struct workqueue_struct *workqueue; struct work_struct rootcg_work; struct list_head rootcg_cmd_list; struct list_head idle_worker_list; struct rb_root worker_tree; struct timer_list timer; bool use_dio; bool sysfs_inited; struct request_queue *lo_queue; struct blk_mq_tag_set tag_set; struct gendisk *lo_disk; struct mutex lo_mutex; bool idr_visible; }; struct loop_cmd { struct list_head list_entry; bool use_aio; /* use AIO interface to handle I/O */ atomic_t ref; /* only for aio */ long ret; struct kiocb iocb; struct bio_vec *bvec; struct cgroup_subsys_state *blkcg_css; struct cgroup_subsys_state *memcg_css; }; #define LOOP_IDLE_WORKER_TIMEOUT (60 * HZ) #define LOOP_DEFAULT_HW_Q_DEPTH 128 static DEFINE_IDR(loop_index_idr); static DEFINE_MUTEX(loop_ctl_mutex); static DEFINE_MUTEX(loop_validate_mutex); /** * loop_global_lock_killable() - take locks for safe loop_validate_file() test * * @lo: struct loop_device * @global: true if @lo is about to bind another "struct loop_device", false otherwise * * Returns 0 on success, -EINTR otherwise. * * Since loop_validate_file() traverses on other "struct loop_device" if * is_loop_device() is true, we need a global lock for serializing concurrent * loop_configure()/loop_change_fd()/__loop_clr_fd() calls. */ static int loop_global_lock_killable(struct loop_device *lo, bool global) { int err; if (global) { err = mutex_lock_killable(&loop_validate_mutex); if (err) return err; } err = mutex_lock_killable(&lo->lo_mutex); if (err && global) mutex_unlock(&loop_validate_mutex); return err; } /** * loop_global_unlock() - release locks taken by loop_global_lock_killable() * * @lo: struct loop_device * @global: true if @lo was about to bind another "struct loop_device", false otherwise */ static void loop_global_unlock(struct loop_device *lo, bool global) { mutex_unlock(&lo->lo_mutex); if (global) mutex_unlock(&loop_validate_mutex); } static int max_part; static int part_shift; static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file) { loff_t loopsize; /* Compute loopsize in bytes */ loopsize = i_size_read(file->f_mapping->host); if (offset > 0) loopsize -= offset; /* offset is beyond i_size, weird but possible */ if (loopsize < 0) return 0; if (sizelimit > 0 && sizelimit < loopsize) loopsize = sizelimit; /* * Unfortunately, if we want to do I/O on the device, * the number of 512-byte sectors has to fit into a sector_t. */ return loopsize >> 9; } static loff_t get_loop_size(struct loop_device *lo, struct file *file) { return get_size(lo->lo_offset, lo->lo_sizelimit, file); } static void __loop_update_dio(struct loop_device *lo, bool dio) { struct file *file = lo->lo_backing_file; struct address_space *mapping = file->f_mapping; struct inode *inode = mapping->host; unsigned short sb_bsize = 0; unsigned dio_align = 0; bool use_dio; if (inode->i_sb->s_bdev) { sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev); dio_align = sb_bsize - 1; } /* * We support direct I/O only if lo_offset is aligned with the * logical I/O size of backing device, and the logical block * size of loop is bigger than the backing device's. * * TODO: the above condition may be loosed in the future, and * direct I/O may be switched runtime at that time because most * of requests in sane applications should be PAGE_SIZE aligned */ if (dio) { if (queue_logical_block_size(lo->lo_queue) >= sb_bsize && !(lo->lo_offset & dio_align) && (file->f_mode & FMODE_CAN_ODIRECT)) use_dio = true; else use_dio = false; } else { use_dio = false; } if (lo->use_dio == use_dio) return; /* flush dirty pages before changing direct IO */ vfs_fsync(file, 0); /* * The flag of LO_FLAGS_DIRECT_IO is handled similarly with * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup * will get updated by ioctl(LOOP_GET_STATUS) */ if (lo->lo_state == Lo_bound) blk_mq_freeze_queue(lo->lo_queue); lo->use_dio = use_dio; if (use_dio) { blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue); lo->lo_flags |= LO_FLAGS_DIRECT_IO; } else { blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue); lo->lo_flags &= ~LO_FLAGS_DIRECT_IO; } if (lo->lo_state == Lo_bound) blk_mq_unfreeze_queue(lo->lo_queue); } /** * loop_set_size() - sets device size and notifies userspace * @lo: struct loop_device to set the size for * @size: new size of the loop device * * Callers must validate that the size passed into this function fits into * a sector_t, eg using loop_validate_size() */ static void loop_set_size(struct loop_device *lo, loff_t size) { if (!set_capacity_and_notify(lo->lo_disk, size)) kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE); } static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos) { struct iov_iter i; ssize_t bw; iov_iter_bvec(&i, ITER_SOURCE, bvec, 1, bvec->bv_len); file_start_write(file); bw = vfs_iter_write(file, &i, ppos, 0); file_end_write(file); if (likely(bw == bvec->bv_len)) return 0; printk_ratelimited(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n", (unsigned long long)*ppos, bvec->bv_len); if (bw >= 0) bw = -EIO; return bw; } static int lo_write_simple(struct loop_device *lo, struct request *rq, loff_t pos) { struct bio_vec bvec; struct req_iterator iter; int ret = 0; rq_for_each_segment(bvec, rq, iter) { ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos); if (ret < 0) break; cond_resched(); } return ret; } static int lo_read_simple(struct loop_device *lo, struct request *rq, loff_t pos) { struct bio_vec bvec; struct req_iterator iter; struct iov_iter i; ssize_t len; rq_for_each_segment(bvec, rq, iter) { iov_iter_bvec(&i, ITER_DEST, &bvec, 1, bvec.bv_len); len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0); if (len < 0) return len; flush_dcache_page(bvec.bv_page); if (len != bvec.bv_len) { struct bio *bio; __rq_for_each_bio(bio, rq) zero_fill_bio(bio); break; } cond_resched(); } return 0; } static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos, int mode) { /* * We use fallocate to manipulate the space mappings used by the image * a.k.a. discard/zerorange. */ struct file *file = lo->lo_backing_file; int ret; mode |= FALLOC_FL_KEEP_SIZE; if (!bdev_max_discard_sectors(lo->lo_device)) return -EOPNOTSUPP; ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq)); if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP)) return -EIO; return ret; } static int lo_req_flush(struct loop_device *lo, struct request *rq) { int ret = vfs_fsync(lo->lo_backing_file, 0); if (unlikely(ret && ret != -EINVAL)) ret = -EIO; return ret; } static void lo_complete_rq(struct request *rq) { struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); blk_status_t ret = BLK_STS_OK; if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) || req_op(rq) != REQ_OP_READ) { if (cmd->ret < 0) ret = errno_to_blk_status(cmd->ret); goto end_io; } /* * Short READ - if we got some data, advance our request and * retry it. If we got no data, end the rest with EIO. */ if (cmd->ret) { blk_update_request(rq, BLK_STS_OK, cmd->ret); cmd->ret = 0; blk_mq_requeue_request(rq, true); } else { if (cmd->use_aio) { struct bio *bio = rq->bio; while (bio) { zero_fill_bio(bio); bio = bio->bi_next; } } ret = BLK_STS_IOERR; end_io: blk_mq_end_request(rq, ret); } } static void lo_rw_aio_do_completion(struct loop_cmd *cmd) { struct request *rq = blk_mq_rq_from_pdu(cmd); if (!atomic_dec_and_test(&cmd->ref)) return; kfree(cmd->bvec); cmd->bvec = NULL; if (likely(!blk_should_fake_timeout(rq->q))) blk_mq_complete_request(rq); } static void lo_rw_aio_complete(struct kiocb *iocb, long ret) { struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb); cmd->ret = ret; lo_rw_aio_do_completion(cmd); } static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, loff_t pos, int rw) { struct iov_iter iter; struct req_iterator rq_iter; struct bio_vec *bvec; struct request *rq = blk_mq_rq_from_pdu(cmd); struct bio *bio = rq->bio; struct file *file = lo->lo_backing_file; struct bio_vec tmp; unsigned int offset; int nr_bvec = 0; int ret; rq_for_each_bvec(tmp, rq, rq_iter) nr_bvec++; if (rq->bio != rq->biotail) { bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec), GFP_NOIO); if (!bvec) return -EIO; cmd->bvec = bvec; /* * The bios of the request may be started from the middle of * the 'bvec' because of bio splitting, so we can't directly * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec * API will take care of all details for us. */ rq_for_each_bvec(tmp, rq, rq_iter) { *bvec = tmp; bvec++; } bvec = cmd->bvec; offset = 0; } else { /* * Same here, this bio may be started from the middle of the * 'bvec' because of bio splitting, so offset from the bvec * must be passed to iov iterator */ offset = bio->bi_iter.bi_bvec_done; bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); } atomic_set(&cmd->ref, 2); iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq)); iter.iov_offset = offset; cmd->iocb.ki_pos = pos; cmd->iocb.ki_filp = file; cmd->iocb.ki_complete = lo_rw_aio_complete; cmd->iocb.ki_flags = IOCB_DIRECT; cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0); if (rw == ITER_SOURCE) ret = call_write_iter(file, &cmd->iocb, &iter); else ret = call_read_iter(file, &cmd->iocb, &iter); lo_rw_aio_do_completion(cmd); if (ret != -EIOCBQUEUED) lo_rw_aio_complete(&cmd->iocb, ret); return 0; } static int do_req_filebacked(struct loop_device *lo, struct request *rq) { struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset; /* * lo_write_simple and lo_read_simple should have been covered * by io submit style function like lo_rw_aio(), one blocker * is that lo_read_simple() need to call flush_dcache_page after * the page is written from kernel, and it isn't easy to handle * this in io submit style function which submits all segments * of the req at one time. And direct read IO doesn't need to * run flush_dcache_page(). */ switch (req_op(rq)) { case REQ_OP_FLUSH: return lo_req_flush(lo, rq); case REQ_OP_WRITE_ZEROES: /* * If the caller doesn't want deallocation, call zeroout to * write zeroes the range. Otherwise, punch them out. */ return lo_fallocate(lo, rq, pos, (rq->cmd_flags & REQ_NOUNMAP) ? FALLOC_FL_ZERO_RANGE : FALLOC_FL_PUNCH_HOLE); case REQ_OP_DISCARD: return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE); case REQ_OP_WRITE: if (cmd->use_aio) return lo_rw_aio(lo, cmd, pos, ITER_SOURCE); else return lo_write_simple(lo, rq, pos); case REQ_OP_READ: if (cmd->use_aio) return lo_rw_aio(lo, cmd, pos, ITER_DEST); else return lo_read_simple(lo, rq, pos); default: WARN_ON_ONCE(1); return -EIO; } } static inline void loop_update_dio(struct loop_device *lo) { __loop_update_dio(lo, (lo->lo_backing_file->f_flags & O_DIRECT) | lo->use_dio); } static void loop_reread_partitions(struct loop_device *lo) { int rc; mutex_lock(&lo->lo_disk->open_mutex); rc = bdev_disk_changed(lo->lo_disk, false); mutex_unlock(&lo->lo_disk->open_mutex); if (rc) pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n", __func__, lo->lo_number, lo->lo_file_name, rc); } static inline int is_loop_device(struct file *file) { struct inode *i = file->f_mapping->host; return i && S_ISBLK(i->i_mode) && imajor(i) == LOOP_MAJOR; } static int loop_validate_file(struct file *file, struct block_device *bdev) { struct inode *inode = file->f_mapping->host; struct file *f = file; /* Avoid recursion */ while (is_loop_device(f)) { struct loop_device *l; lockdep_assert_held(&loop_validate_mutex); if (f->f_mapping->host->i_rdev == bdev->bd_dev) return -EBADF; l = I_BDEV(f->f_mapping->host)->bd_disk->private_data; if (l->lo_state != Lo_bound) return -EINVAL; /* Order wrt setting lo->lo_backing_file in loop_configure(). */ rmb(); f = l->lo_backing_file; } if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) return -EINVAL; return 0; } /* * loop_change_fd switched the backing store of a loopback device to * a new file. This is useful for operating system installers to free up * the original file and in High Availability environments to switch to * an alternative location for the content in case of server meltdown. * This can only work if the loop device is used read-only, and if the * new backing store is the same size and type as the old backing store. */ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev, unsigned int arg) { struct file *file = fget(arg); struct file *old_file; int error; bool partscan; bool is_loop; if (!file) return -EBADF; /* suppress uevents while reconfiguring the device */ dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1); is_loop = is_loop_device(file); error = loop_global_lock_killable(lo, is_loop); if (error) goto out_putf; error = -ENXIO; if (lo->lo_state != Lo_bound) goto out_err; /* the loop device has to be read-only */ error = -EINVAL; if (!(lo->lo_flags & LO_FLAGS_READ_ONLY)) goto out_err; error = loop_validate_file(file, bdev); if (error) goto out_err; old_file = lo->lo_backing_file; error = -EINVAL; /* size of the new backing store needs to be the same */ if (get_loop_size(lo, file) != get_loop_size(lo, old_file)) goto out_err; /* and ... switch */ disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE); blk_mq_freeze_queue(lo->lo_queue); mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask); lo->lo_backing_file = file; lo->old_gfp_mask = mapping_gfp_mask(file->f_mapping); mapping_set_gfp_mask(file->f_mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); loop_update_dio(lo); blk_mq_unfreeze_queue(lo->lo_queue); partscan = lo->lo_flags & LO_FLAGS_PARTSCAN; loop_global_unlock(lo, is_loop); /* * Flush loop_validate_file() before fput(), for l->lo_backing_file * might be pointing at old_file which might be the last reference. */ if (!is_loop) { mutex_lock(&loop_validate_mutex); mutex_unlock(&loop_validate_mutex); } /* * We must drop file reference outside of lo_mutex as dropping * the file ref can take open_mutex which creates circular locking * dependency. */ fput(old_file); if (partscan) loop_reread_partitions(lo); error = 0; done: /* enable and uncork uevent now that we are done */ dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0); return error; out_err: loop_global_unlock(lo, is_loop); out_putf: fput(file); goto done; } /* loop sysfs attributes */ static ssize_t loop_attr_show(struct device *dev, char *page, ssize_t (*callback)(struct loop_device *, char *)) { struct gendisk *disk = dev_to_disk(dev); struct loop_device *lo = disk->private_data; return callback(lo, page); } #define LOOP_ATTR_RO(_name) \ static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \ static ssize_t loop_attr_do_show_##_name(struct device *d, \ struct device_attribute *attr, char *b) \ { \ return loop_attr_show(d, b, loop_attr_##_name##_show); \ } \ static struct device_attribute loop_attr_##_name = \ __ATTR(_name, 0444, loop_attr_do_show_##_name, NULL); static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf) { ssize_t ret; char *p = NULL; spin_lock_irq(&lo->lo_lock); if (lo->lo_backing_file) p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1); spin_unlock_irq(&lo->lo_lock); if (IS_ERR_OR_NULL(p)) ret = PTR_ERR(p); else { ret = strlen(p); memmove(buf, p, ret); buf[ret++] = '\n'; buf[ret] = 0; } return ret; } static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf) { return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_offset); } static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf) { return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit); } static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf) { int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR); return sysfs_emit(buf, "%s\n", autoclear ? "1" : "0"); } static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf) { int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN); return sysfs_emit(buf, "%s\n", partscan ? "1" : "0"); } static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf) { int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO); return sysfs_emit(buf, "%s\n", dio ? "1" : "0"); } LOOP_ATTR_RO(backing_file); LOOP_ATTR_RO(offset); LOOP_ATTR_RO(sizelimit); LOOP_ATTR_RO(autoclear); LOOP_ATTR_RO(partscan); LOOP_ATTR_RO(dio); static struct attribute *loop_attrs[] = { &loop_attr_backing_file.attr, &loop_attr_offset.attr, &loop_attr_sizelimit.attr, &loop_attr_autoclear.attr, &loop_attr_partscan.attr, &loop_attr_dio.attr, NULL, }; static struct attribute_group loop_attribute_group = { .name = "loop", .attrs= loop_attrs, }; static void loop_sysfs_init(struct loop_device *lo) { lo->sysfs_inited = !sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj, &loop_attribute_group); } static void loop_sysfs_exit(struct loop_device *lo) { if (lo->sysfs_inited) sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj, &loop_attribute_group); } static void loop_config_discard(struct loop_device *lo) { struct file *file = lo->lo_backing_file; struct inode *inode = file->f_mapping->host; struct request_queue *q = lo->lo_queue; u32 granularity, max_discard_sectors; /* * If the backing device is a block device, mirror its zeroing * capability. Set the discard sectors to the block device's zeroing * capabilities because loop discards result in blkdev_issue_zeroout(), * not blkdev_issue_discard(). This maintains consistent behavior with * file-backed loop devices: discarded regions read back as zero. */ if (S_ISBLK(inode->i_mode)) { struct request_queue *backingq = bdev_get_queue(I_BDEV(inode)); max_discard_sectors = backingq->limits.max_write_zeroes_sectors; granularity = bdev_discard_granularity(I_BDEV(inode)) ?: queue_physical_block_size(backingq); /* * We use punch hole to reclaim the free space used by the * image a.k.a. discard. */ } else if (!file->f_op->fallocate) { max_discard_sectors = 0; granularity = 0; } else { struct kstatfs sbuf; max_discard_sectors = UINT_MAX >> 9; if (!vfs_statfs(&file->f_path, &sbuf)) granularity = sbuf.f_bsize; else max_discard_sectors = 0; } if (max_discard_sectors) { q->limits.discard_granularity = granularity; blk_queue_max_discard_sectors(q, max_discard_sectors); blk_queue_max_write_zeroes_sectors(q, max_discard_sectors); } else { q->limits.discard_granularity = 0; blk_queue_max_discard_sectors(q, 0); blk_queue_max_write_zeroes_sectors(q, 0); } } struct loop_worker { struct rb_node rb_node; struct work_struct work; struct list_head cmd_list; struct list_head idle_list; struct loop_device *lo; struct cgroup_subsys_state *blkcg_css; unsigned long last_ran_at; }; static void loop_workfn(struct work_struct *work); #ifdef CONFIG_BLK_CGROUP static inline int queue_on_root_worker(struct cgroup_subsys_state *css) { return !css || css == blkcg_root_css; } #else static inline int queue_on_root_worker(struct cgroup_subsys_state *css) { return !css; } #endif static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd) { struct rb_node **node, *parent = NULL; struct loop_worker *cur_worker, *worker = NULL; struct work_struct *work; struct list_head *cmd_list; spin_lock_irq(&lo->lo_work_lock); if (queue_on_root_worker(cmd->blkcg_css)) goto queue_work; node = &lo->worker_tree.rb_node; while (*node) { parent = *node; cur_worker = container_of(*node, struct loop_worker, rb_node); if (cur_worker->blkcg_css == cmd->blkcg_css) { worker = cur_worker; break; } else if ((long)cur_worker->blkcg_css < (long)cmd->blkcg_css) { node = &(*node)->rb_left; } else { node = &(*node)->rb_right; } } if (worker) goto queue_work; worker = kzalloc(sizeof(struct loop_worker), GFP_NOWAIT | __GFP_NOWARN); /* * In the event we cannot allocate a worker, just queue on the * rootcg worker and issue the I/O as the rootcg */ if (!worker) { cmd->blkcg_css = NULL; if (cmd->memcg_css) css_put(cmd->memcg_css); cmd->memcg_css = NULL; goto queue_work; } worker->blkcg_css = cmd->blkcg_css; css_get(worker->blkcg_css); INIT_WORK(&worker->work, loop_workfn); INIT_LIST_HEAD(&worker->cmd_list); INIT_LIST_HEAD(&worker->idle_list); worker->lo = lo; rb_link_node(&worker->rb_node, parent, node); rb_insert_color(&worker->rb_node, &lo->worker_tree); queue_work: if (worker) { /* * We need to remove from the idle list here while * holding the lock so that the idle timer doesn't * free the worker */ if (!list_empty(&worker->idle_list)) list_del_init(&worker->idle_list); work = &worker->work; cmd_list = &worker->cmd_list; } else { work = &lo->rootcg_work; cmd_list = &lo->rootcg_cmd_list; } list_add_tail(&cmd->list_entry, cmd_list); queue_work(lo->workqueue, work); spin_unlock_irq(&lo->lo_work_lock); } static void loop_set_timer(struct loop_device *lo) { timer_reduce(&lo->timer, jiffies + LOOP_IDLE_WORKER_TIMEOUT); } static void loop_free_idle_workers(struct loop_device *lo, bool delete_all) { struct loop_worker *pos, *worker; spin_lock_irq(&lo->lo_work_lock); list_for_each_entry_safe(worker, pos, &lo->idle_worker_list, idle_list) { if (!delete_all && time_is_after_jiffies(worker->last_ran_at + LOOP_IDLE_WORKER_TIMEOUT)) break; list_del(&worker->idle_list); rb_erase(&worker->rb_node, &lo->worker_tree); css_put(worker->blkcg_css); kfree(worker); } if (!list_empty(&lo->idle_worker_list)) loop_set_timer(lo); spin_unlock_irq(&lo->lo_work_lock); } static void loop_free_idle_workers_timer(struct timer_list *timer) { struct loop_device *lo = container_of(timer, struct loop_device, timer); return loop_free_idle_workers(lo, false); } static void loop_update_rotational(struct loop_device *lo) { struct file *file = lo->lo_backing_file; struct inode *file_inode = file->f_mapping->host; struct block_device *file_bdev = file_inode->i_sb->s_bdev; struct request_queue *q = lo->lo_queue; bool nonrot = true; /* not all filesystems (e.g. tmpfs) have a sb->s_bdev */ if (file_bdev) nonrot = bdev_nonrot(file_bdev); if (nonrot) blk_queue_flag_set(QUEUE_FLAG_NONROT, q); else blk_queue_flag_clear(QUEUE_FLAG_NONROT, q); } /** * loop_set_status_from_info - configure device from loop_info * @lo: struct loop_device to configure * @info: struct loop_info64 to configure the device with * * Configures the loop device parameters according to the passed * in loop_info64 configuration. */ static int loop_set_status_from_info(struct loop_device *lo, const struct loop_info64 *info) { if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE) return -EINVAL; switch (info->lo_encrypt_type) { case LO_CRYPT_NONE: break; case LO_CRYPT_XOR: pr_warn("support for the xor transformation has been removed.\n"); return -EINVAL; case LO_CRYPT_CRYPTOAPI: pr_warn("support for cryptoloop has been removed. Use dm-crypt instead.\n"); return -EINVAL; default: return -EINVAL; } /* Avoid assigning overflow values */ if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX) return -EOVERFLOW; lo->lo_offset = info->lo_offset; lo->lo_sizelimit = info->lo_sizelimit; memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE); lo->lo_file_name[LO_NAME_SIZE-1] = 0; lo->lo_flags = info->lo_flags; return 0; } static int loop_configure(struct loop_device *lo, fmode_t mode, struct block_device *bdev, const struct loop_config *config) { struct file *file = fget(config->fd); struct inode *inode; struct address_space *mapping; int error; loff_t size; bool partscan; unsigned short bsize; bool is_loop; if (!file) return -EBADF; is_loop = is_loop_device(file); /* This is safe, since we have a reference from open(). */ __module_get(THIS_MODULE); /* * If we don't hold exclusive handle for the device, upgrade to it * here to avoid changing device under exclusive owner. */ if (!(mode & FMODE_EXCL)) { error = bd_prepare_to_claim(bdev, loop_configure); if (error) goto out_putf; } error = loop_global_lock_killable(lo, is_loop); if (error) goto out_bdev; error = -EBUSY; if (lo->lo_state != Lo_unbound) goto out_unlock; error = loop_validate_file(file, bdev); if (error) goto out_unlock; mapping = file->f_mapping; inode = mapping->host; if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) { error = -EINVAL; goto out_unlock; } if (config->block_size) { error = blk_validate_block_size(config->block_size); if (error) goto out_unlock; } error = loop_set_status_from_info(lo, &config->info); if (error) goto out_unlock; if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) || !file->f_op->write_iter) lo->lo_flags |= LO_FLAGS_READ_ONLY; if (!lo->workqueue) { lo->workqueue = alloc_workqueue("loop%d", WQ_UNBOUND | WQ_FREEZABLE, 0, lo->lo_number); if (!lo->workqueue) { error = -ENOMEM; goto out_unlock; } } /* suppress uevents while reconfiguring the device */ dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1); disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE); set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0); lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO; lo->lo_device = bdev; lo->lo_backing_file = file; lo->old_gfp_mask = mapping_gfp_mask(mapping); mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync) blk_queue_write_cache(lo->lo_queue, true, false); if (config->block_size) bsize = config->block_size; else if ((lo->lo_backing_file->f_flags & O_DIRECT) && inode->i_sb->s_bdev) /* In case of direct I/O, match underlying block size */ bsize = bdev_logical_block_size(inode->i_sb->s_bdev); else bsize = 512; blk_queue_logical_block_size(lo->lo_queue, bsize); blk_queue_physical_block_size(lo->lo_queue, bsize); blk_queue_io_min(lo->lo_queue, bsize); loop_config_discard(lo); loop_update_rotational(lo); loop_update_dio(lo); loop_sysfs_init(lo); size = get_loop_size(lo, file); loop_set_size(lo, size); /* Order wrt reading lo_state in loop_validate_file(). */ wmb(); lo->lo_state = Lo_bound; if (part_shift) lo->lo_flags |= LO_FLAGS_PARTSCAN; partscan = lo->lo_flags & LO_FLAGS_PARTSCAN; if (partscan) clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state); /* enable and uncork uevent now that we are done */ dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0); loop_global_unlock(lo, is_loop); if (partscan) loop_reread_partitions(lo); if (!(mode & FMODE_EXCL)) bd_abort_claiming(bdev, loop_configure); return 0; out_unlock: loop_global_unlock(lo, is_loop); out_bdev: if (!(mode & FMODE_EXCL)) bd_abort_claiming(bdev, loop_configure); out_putf: fput(file); /* This is safe: open() is still holding a reference. */ module_put(THIS_MODULE); return error; } static void __loop_clr_fd(struct loop_device *lo, bool release) { struct file *filp; gfp_t gfp = lo->old_gfp_mask; if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags)) blk_queue_write_cache(lo->lo_queue, false, false); /* * Freeze the request queue when unbinding on a live file descriptor and * thus an open device. When called from ->release we are guaranteed * that there is no I/O in progress already. */ if (!release) blk_mq_freeze_queue(lo->lo_queue); spin_lock_irq(&lo->lo_lock); filp = lo->lo_backing_file; lo->lo_backing_file = NULL; spin_unlock_irq(&lo->lo_lock); lo->lo_device = NULL; lo->lo_offset = 0; lo->lo_sizelimit = 0; memset(lo->lo_file_name, 0, LO_NAME_SIZE); blk_queue_logical_block_size(lo->lo_queue, 512); blk_queue_physical_block_size(lo->lo_queue, 512); blk_queue_io_min(lo->lo_queue, 512); invalidate_disk(lo->lo_disk); loop_sysfs_exit(lo); /* let user-space know about this change */ kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE); mapping_set_gfp_mask(filp->f_mapping, gfp); /* This is safe: open() is still holding a reference. */ module_put(THIS_MODULE); if (!release) blk_mq_unfreeze_queue(lo->lo_queue); disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE); if (lo->lo_flags & LO_FLAGS_PARTSCAN) { int err; /* * open_mutex has been held already in release path, so don't * acquire it if this function is called in such case. * * If the reread partition isn't from release path, lo_refcnt * must be at least one and it can only become zero when the * current holder is released. */ if (!release) mutex_lock(&lo->lo_disk->open_mutex); err = bdev_disk_changed(lo->lo_disk, false); if (!release) mutex_unlock(&lo->lo_disk->open_mutex); if (err) pr_warn("%s: partition scan of loop%d failed (rc=%d)\n", __func__, lo->lo_number, err); /* Device is gone, no point in returning error */ } /* * lo->lo_state is set to Lo_unbound here after above partscan has * finished. There cannot be anybody else entering __loop_clr_fd() as * Lo_rundown state protects us from all the other places trying to * change the 'lo' device. */ lo->lo_flags = 0; if (!part_shift) set_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state); mutex_lock(&lo->lo_mutex); lo->lo_state = Lo_unbound; mutex_unlock(&lo->lo_mutex); /* * Need not hold lo_mutex to fput backing file. Calling fput holding * lo_mutex triggers a circular lock dependency possibility warning as * fput can take open_mutex which is usually taken before lo_mutex. */ fput(filp); } static int loop_clr_fd(struct loop_device *lo) { int err; /* * Since lo_ioctl() is called without locks held, it is possible that * loop_configure()/loop_change_fd() and loop_clr_fd() run in parallel. * * Therefore, use global lock when setting Lo_rundown state in order to * make sure that loop_validate_file() will fail if the "struct file" * which loop_configure()/loop_change_fd() found via fget() was this * loop device. */ err = loop_global_lock_killable(lo, true); if (err) return err; if (lo->lo_state != Lo_bound) { loop_global_unlock(lo, true); return -ENXIO; } /* * If we've explicitly asked to tear down the loop device, * and it has an elevated reference count, set it for auto-teardown when * the last reference goes away. This stops $!~#$@ udev from * preventing teardown because it decided that it needs to run blkid on * the loopback device whenever they appear. xfstests is notorious for * failing tests because blkid via udev races with a losetup * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d * command to fail with EBUSY. */ if (disk_openers(lo->lo_disk) > 1) { lo->lo_flags |= LO_FLAGS_AUTOCLEAR; loop_global_unlock(lo, true); return 0; } lo->lo_state = Lo_rundown; loop_global_unlock(lo, true); __loop_clr_fd(lo, false); return 0; } static int loop_set_status(struct loop_device *lo, const struct loop_info64 *info) { int err; int prev_lo_flags; bool partscan = false; bool size_changed = false; err = mutex_lock_killable(&lo->lo_mutex); if (err) return err; if (lo->lo_state != Lo_bound) { err = -ENXIO; goto out_unlock; } if (lo->lo_offset != info->lo_offset || lo->lo_sizelimit != info->lo_sizelimit) { size_changed = true; sync_blockdev(lo->lo_device); invalidate_bdev(lo->lo_device); } /* I/O need to be drained during transfer transition */ blk_mq_freeze_queue(lo->lo_queue); prev_lo_flags = lo->lo_flags; err = loop_set_status_from_info(lo, info); if (err) goto out_unfreeze; /* Mask out flags that can't be set using LOOP_SET_STATUS. */ lo->lo_flags &= LOOP_SET_STATUS_SETTABLE_FLAGS; /* For those flags, use the previous values instead */ lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_SETTABLE_FLAGS; /* For flags that can't be cleared, use previous values too */ lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_CLEARABLE_FLAGS; if (size_changed) { loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit, lo->lo_backing_file); loop_set_size(lo, new_size); } loop_config_discard(lo); /* update dio if lo_offset or transfer is changed */ __loop_update_dio(lo, lo->use_dio); out_unfreeze: blk_mq_unfreeze_queue(lo->lo_queue); if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) && !(prev_lo_flags & LO_FLAGS_PARTSCAN)) { clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state); partscan = true; } out_unlock: mutex_unlock(&lo->lo_mutex); if (partscan) loop_reread_partitions(lo); return err; } static int loop_get_status(struct loop_device *lo, struct loop_info64 *info) { struct path path; struct kstat stat; int ret; ret = mutex_lock_killable(&lo->lo_mutex); if (ret) return ret; if (lo->lo_state != Lo_bound) { mutex_unlock(&lo->lo_mutex); return -ENXIO; } memset(info, 0, sizeof(*info)); info->lo_number = lo->lo_number; info->lo_offset = lo->lo_offset; info->lo_sizelimit = lo->lo_sizelimit; info->lo_flags = lo->lo_flags; memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE); /* Drop lo_mutex while we call into the filesystem. */ path = lo->lo_backing_file->f_path; path_get(&path); mutex_unlock(&lo->lo_mutex); ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT); if (!ret) { info->lo_device = huge_encode_dev(stat.dev); info->lo_inode = stat.ino; info->lo_rdevice = huge_encode_dev(stat.rdev); } path_put(&path); return ret; } static void loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64) { memset(info64, 0, sizeof(*info64)); info64->lo_number = info->lo_number; info64->lo_device = info->lo_device; info64->lo_inode = info->lo_inode; info64->lo_rdevice = info->lo_rdevice; info64->lo_offset = info->lo_offset; info64->lo_sizelimit = 0; info64->lo_flags = info->lo_flags; memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE); } static int loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info) { memset(info, 0, sizeof(*info)); info->lo_number = info64->lo_number; info->lo_device = info64->lo_device; info->lo_inode = info64->lo_inode; info->lo_rdevice = info64->lo_rdevice; info->lo_offset = info64->lo_offset; info->lo_flags = info64->lo_flags; memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE); /* error in case values were truncated */ if (info->lo_device != info64->lo_device || info->lo_rdevice != info64->lo_rdevice || info->lo_inode != info64->lo_inode || info->lo_offset != info64->lo_offset) return -EOVERFLOW; return 0; } static int loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg) { struct loop_info info; struct loop_info64 info64; if (copy_from_user(&info, arg, sizeof (struct loop_info))) return -EFAULT; loop_info64_from_old(&info, &info64); return loop_set_status(lo, &info64); } static int loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg) { struct loop_info64 info64; if (copy_from_user(&info64, arg, sizeof (struct loop_info64))) return -EFAULT; return loop_set_status(lo, &info64); } static int loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) { struct loop_info info; struct loop_info64 info64; int err; if (!arg) return -EINVAL; err = loop_get_status(lo, &info64); if (!err) err = loop_info64_to_old(&info64, &info); if (!err && copy_to_user(arg, &info, sizeof(info))) err = -EFAULT; return err; } static int loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) { struct loop_info64 info64; int err; if (!arg) return -EINVAL; err = loop_get_status(lo, &info64); if (!err && copy_to_user(arg, &info64, sizeof(info64))) err = -EFAULT; return err; } static int loop_set_capacity(struct loop_device *lo) { loff_t size; if (unlikely(lo->lo_state != Lo_bound)) return -ENXIO; size = get_loop_size(lo, lo->lo_backing_file); loop_set_size(lo, size); return 0; } static int loop_set_dio(struct loop_device *lo, unsigned long arg) { int error = -ENXIO; if (lo->lo_state != Lo_bound) goto out; __loop_update_dio(lo, !!arg); if (lo->use_dio == !!arg) return 0; error = -EINVAL; out: return error; } static int loop_set_block_size(struct loop_device *lo, unsigned long arg) { int err = 0; if (lo->lo_state != Lo_bound) return -ENXIO; err = blk_validate_block_size(arg); if (err) return err; if (lo->lo_queue->limits.logical_block_size == arg) return 0; sync_blockdev(lo->lo_device); invalidate_bdev(lo->lo_device); blk_mq_freeze_queue(lo->lo_queue); blk_queue_logical_block_size(lo->lo_queue, arg); blk_queue_physical_block_size(lo->lo_queue, arg); blk_queue_io_min(lo->lo_queue, arg); loop_update_dio(lo); blk_mq_unfreeze_queue(lo->lo_queue); return err; } static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd, unsigned long arg) { int err; err = mutex_lock_killable(&lo->lo_mutex); if (err) return err; switch (cmd) { case LOOP_SET_CAPACITY: err = loop_set_capacity(lo); break; case LOOP_SET_DIRECT_IO: err = loop_set_dio(lo, arg); break; case LOOP_SET_BLOCK_SIZE: err = loop_set_block_size(lo, arg); break; default: err = -EINVAL; } mutex_unlock(&lo->lo_mutex); return err; } static int lo_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg) { struct loop_device *lo = bdev->bd_disk->private_data; void __user *argp = (void __user *) arg; int err; switch (cmd) { case LOOP_SET_FD: { /* * Legacy case - pass in a zeroed out struct loop_config with * only the file descriptor set , which corresponds with the * default parameters we'd have used otherwise. */ struct loop_config config; memset(&config, 0, sizeof(config)); config.fd = arg; return loop_configure(lo, mode, bdev, &config); } case LOOP_CONFIGURE: { struct loop_config config; if (copy_from_user(&config, argp, sizeof(config))) return -EFAULT; return loop_configure(lo, mode, bdev, &config); } case LOOP_CHANGE_FD: return loop_change_fd(lo, bdev, arg); case LOOP_CLR_FD: return loop_clr_fd(lo); case LOOP_SET_STATUS: err = -EPERM; if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) { err = loop_set_status_old(lo, argp); } break; case LOOP_GET_STATUS: return loop_get_status_old(lo, argp); case LOOP_SET_STATUS64: err = -EPERM; if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) { err = loop_set_status64(lo, argp); } break; case LOOP_GET_STATUS64: return loop_get_status64(lo, argp); case LOOP_SET_CAPACITY: case LOOP_SET_DIRECT_IO: case LOOP_SET_BLOCK_SIZE: if (!(mode & FMODE_WRITE) && !capable(CAP_SYS_ADMIN)) return -EPERM; fallthrough; default: err = lo_simple_ioctl(lo, cmd, arg); break; } return err; } #ifdef CONFIG_COMPAT struct compat_loop_info { compat_int_t lo_number; /* ioctl r/o */ compat_dev_t lo_device; /* ioctl r/o */ compat_ulong_t lo_inode; /* ioctl r/o */ compat_dev_t lo_rdevice; /* ioctl r/o */ compat_int_t lo_offset; compat_int_t lo_encrypt_type; /* obsolete, ignored */ compat_int_t lo_encrypt_key_size; /* ioctl w/o */ compat_int_t lo_flags; /* ioctl r/o */ char lo_name[LO_NAME_SIZE]; unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */ compat_ulong_t lo_init[2]; char reserved[4]; }; /* * Transfer 32-bit compatibility structure in userspace to 64-bit loop info * - noinlined to reduce stack space usage in main part of driver */ static noinline int loop_info64_from_compat(const struct compat_loop_info __user *arg, struct loop_info64 *info64) { struct compat_loop_info info; if (copy_from_user(&info, arg, sizeof(info))) return -EFAULT; memset(info64, 0, sizeof(*info64)); info64->lo_number = info.lo_number; info64->lo_device = info.lo_device; info64->lo_inode = info.lo_inode; info64->lo_rdevice = info.lo_rdevice; info64->lo_offset = info.lo_offset; info64->lo_sizelimit = 0; info64->lo_flags = info.lo_flags; memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE); return 0; } /* * Transfer 64-bit loop info to 32-bit compatibility structure in userspace * - noinlined to reduce stack space usage in main part of driver */ static noinline int loop_info64_to_compat(const struct loop_info64 *info64, struct compat_loop_info __user *arg) { struct compat_loop_info info; memset(&info, 0, sizeof(info)); info.lo_number = info64->lo_number; info.lo_device = info64->lo_device; info.lo_inode = info64->lo_inode; info.lo_rdevice = info64->lo_rdevice; info.lo_offset = info64->lo_offset; info.lo_flags = info64->lo_flags; memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE); /* error in case values were truncated */ if (info.lo_device != info64->lo_device || info.lo_rdevice != info64->lo_rdevice || info.lo_inode != info64->lo_inode || info.lo_offset != info64->lo_offset) return -EOVERFLOW; if (copy_to_user(arg, &info, sizeof(info))) return -EFAULT; return 0; } static int loop_set_status_compat(struct loop_device *lo, const struct compat_loop_info __user *arg) { struct loop_info64 info64; int ret; ret = loop_info64_from_compat(arg, &info64); if (ret < 0) return ret; return loop_set_status(lo, &info64); } static int loop_get_status_compat(struct loop_device *lo, struct compat_loop_info __user *arg) { struct loop_info64 info64; int err; if (!arg) return -EINVAL; err = loop_get_status(lo, &info64); if (!err) err = loop_info64_to_compat(&info64, arg); return err; } static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg) { struct loop_device *lo = bdev->bd_disk->private_data; int err; switch(cmd) { case LOOP_SET_STATUS: err = loop_set_status_compat(lo, (const struct compat_loop_info __user *)arg); break; case LOOP_GET_STATUS: err = loop_get_status_compat(lo, (struct compat_loop_info __user *)arg); break; case LOOP_SET_CAPACITY: case LOOP_CLR_FD: case LOOP_GET_STATUS64: case LOOP_SET_STATUS64: case LOOP_CONFIGURE: arg = (unsigned long) compat_ptr(arg); fallthrough; case LOOP_SET_FD: case LOOP_CHANGE_FD: case LOOP_SET_BLOCK_SIZE: case LOOP_SET_DIRECT_IO: err = lo_ioctl(bdev, mode, cmd, arg); break; default: err = -ENOIOCTLCMD; break; } return err; } #endif static void lo_release(struct gendisk *disk, fmode_t mode) { struct loop_device *lo = disk->private_data; if (disk_openers(disk) > 0) return; mutex_lock(&lo->lo_mutex); if (lo->lo_state == Lo_bound && (lo->lo_flags & LO_FLAGS_AUTOCLEAR)) { lo->lo_state = Lo_rundown; mutex_unlock(&lo->lo_mutex); /* * In autoclear mode, stop the loop thread * and remove configuration after last close. */ __loop_clr_fd(lo, true); return; } mutex_unlock(&lo->lo_mutex); } static void lo_free_disk(struct gendisk *disk) { struct loop_device *lo = disk->private_data; if (lo->workqueue) destroy_workqueue(lo->workqueue); loop_free_idle_workers(lo, true); timer_shutdown_sync(&lo->timer); mutex_destroy(&lo->lo_mutex); kfree(lo); } static const struct block_device_operations lo_fops = { .owner = THIS_MODULE, .release = lo_release, .ioctl = lo_ioctl, #ifdef CONFIG_COMPAT .compat_ioctl = lo_compat_ioctl, #endif .free_disk = lo_free_disk, }; /* * And now the modules code and kernel interface. */ /* * If max_loop is specified, create that many devices upfront. * This also becomes a hard limit. If max_loop is not specified, * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module * init time. Loop devices can be requested on-demand with the * /dev/loop-control interface, or be instantiated by accessing * a 'dead' device node. */ static int max_loop = CONFIG_BLK_DEV_LOOP_MIN_COUNT; module_param(max_loop, int, 0444); MODULE_PARM_DESC(max_loop, "Maximum number of loop devices"); module_param(max_part, int, 0444); MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device"); static int hw_queue_depth = LOOP_DEFAULT_HW_Q_DEPTH; static int loop_set_hw_queue_depth(const char *s, const struct kernel_param *p) { int qd, ret; ret = kstrtoint(s, 0, &qd); if (ret < 0) return ret; if (qd < 1) return -EINVAL; hw_queue_depth = qd; return 0; } static const struct kernel_param_ops loop_hw_qdepth_param_ops = { .set = loop_set_hw_queue_depth, .get = param_get_int, }; device_param_cb(hw_queue_depth, &loop_hw_qdepth_param_ops, &hw_queue_depth, 0444); MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: " __stringify(LOOP_DEFAULT_HW_Q_DEPTH)); MODULE_LICENSE("GPL"); MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR); static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx, const struct blk_mq_queue_data *bd) { struct request *rq = bd->rq; struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); struct loop_device *lo = rq->q->queuedata; blk_mq_start_request(rq); if (lo->lo_state != Lo_bound) return BLK_STS_IOERR; switch (req_op(rq)) { case REQ_OP_FLUSH: case REQ_OP_DISCARD: case REQ_OP_WRITE_ZEROES: cmd->use_aio = false; break; default: cmd->use_aio = lo->use_dio; break; } /* always use the first bio's css */ cmd->blkcg_css = NULL; cmd->memcg_css = NULL; #ifdef CONFIG_BLK_CGROUP if (rq->bio) { cmd->blkcg_css = bio_blkcg_css(rq->bio); #ifdef CONFIG_MEMCG if (cmd->blkcg_css) { cmd->memcg_css = cgroup_get_e_css(cmd->blkcg_css->cgroup, &memory_cgrp_subsys); } #endif } #endif loop_queue_work(lo, cmd); return BLK_STS_OK; } static void loop_handle_cmd(struct loop_cmd *cmd) { struct cgroup_subsys_state *cmd_blkcg_css = cmd->blkcg_css; struct cgroup_subsys_state *cmd_memcg_css = cmd->memcg_css; struct request *rq = blk_mq_rq_from_pdu(cmd); const bool write = op_is_write(req_op(rq)); struct loop_device *lo = rq->q->queuedata; int ret = 0; struct mem_cgroup *old_memcg = NULL; const bool use_aio = cmd->use_aio; if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) { ret = -EIO; goto failed; } if (cmd_blkcg_css) kthread_associate_blkcg(cmd_blkcg_css); if (cmd_memcg_css) old_memcg = set_active_memcg( mem_cgroup_from_css(cmd_memcg_css)); /* * do_req_filebacked() may call blk_mq_complete_request() synchronously * or asynchronously if using aio. Hence, do not touch 'cmd' after * do_req_filebacked() has returned unless we are sure that 'cmd' has * not yet been completed. */ ret = do_req_filebacked(lo, rq); if (cmd_blkcg_css) kthread_associate_blkcg(NULL); if (cmd_memcg_css) { set_active_memcg(old_memcg); css_put(cmd_memcg_css); } failed: /* complete non-aio request */ if (!use_aio || ret) { if (ret == -EOPNOTSUPP) cmd->ret = ret; else cmd->ret = ret ? -EIO : 0; if (likely(!blk_should_fake_timeout(rq->q))) blk_mq_complete_request(rq); } } static void loop_process_work(struct loop_worker *worker, struct list_head *cmd_list, struct loop_device *lo) { int orig_flags = current->flags; struct loop_cmd *cmd; current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO; spin_lock_irq(&lo->lo_work_lock); while (!list_empty(cmd_list)) { cmd = container_of( cmd_list->next, struct loop_cmd, list_entry); list_del(cmd_list->next); spin_unlock_irq(&lo->lo_work_lock); loop_handle_cmd(cmd); cond_resched(); spin_lock_irq(&lo->lo_work_lock); } /* * We only add to the idle list if there are no pending cmds * *and* the worker will not run again which ensures that it * is safe to free any worker on the idle list */ if (worker && !work_pending(&worker->work)) { worker->last_ran_at = jiffies; list_add_tail(&worker->idle_list, &lo->idle_worker_list); loop_set_timer(lo); } spin_unlock_irq(&lo->lo_work_lock); current->flags = orig_flags; } static void loop_workfn(struct work_struct *work) { struct loop_worker *worker = container_of(work, struct loop_worker, work); loop_process_work(worker, &worker->cmd_list, worker->lo); } static void loop_rootcg_workfn(struct work_struct *work) { struct loop_device *lo = container_of(work, struct loop_device, rootcg_work); loop_process_work(NULL, &lo->rootcg_cmd_list, lo); } static const struct blk_mq_ops loop_mq_ops = { .queue_rq = loop_queue_rq, .complete = lo_complete_rq, }; static int loop_add(int i) { struct loop_device *lo; struct gendisk *disk; int err; err = -ENOMEM; lo = kzalloc(sizeof(*lo), GFP_KERNEL); if (!lo) goto out; lo->worker_tree = RB_ROOT; INIT_LIST_HEAD(&lo->idle_worker_list); timer_setup(&lo->timer, loop_free_idle_workers_timer, TIMER_DEFERRABLE); lo->lo_state = Lo_unbound; err = mutex_lock_killable(&loop_ctl_mutex); if (err) goto out_free_dev; /* allocate id, if @id >= 0, we're requesting that specific id */ if (i >= 0) { err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL); if (err == -ENOSPC) err = -EEXIST; } else { err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL); } mutex_unlock(&loop_ctl_mutex); if (err < 0) goto out_free_dev; i = err; lo->tag_set.ops = &loop_mq_ops; lo->tag_set.nr_hw_queues = 1; lo->tag_set.queue_depth = hw_queue_depth; lo->tag_set.numa_node = NUMA_NO_NODE; lo->tag_set.cmd_size = sizeof(struct loop_cmd); lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING | BLK_MQ_F_NO_SCHED_BY_DEFAULT; lo->tag_set.driver_data = lo; err = blk_mq_alloc_tag_set(&lo->tag_set); if (err) goto out_free_idr; disk = lo->lo_disk = blk_mq_alloc_disk(&lo->tag_set, lo); if (IS_ERR(disk)) { err = PTR_ERR(disk); goto out_cleanup_tags; } lo->lo_queue = lo->lo_disk->queue; blk_queue_max_hw_sectors(lo->lo_queue, BLK_DEF_MAX_SECTORS); /* * By default, we do buffer IO, so it doesn't make sense to enable * merge because the I/O submitted to backing file is handled page by * page. For directio mode, merge does help to dispatch bigger request * to underlayer disk. We will enable merge once directio is enabled. */ blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue); /* * Disable partition scanning by default. The in-kernel partition * scanning can be requested individually per-device during its * setup. Userspace can always add and remove partitions from all * devices. The needed partition minors are allocated from the * extended minor space, the main loop device numbers will continue * to match the loop minors, regardless of the number of partitions * used. * * If max_part is given, partition scanning is globally enabled for * all loop devices. The minors for the main loop devices will be * multiples of max_part. * * Note: Global-for-all-devices, set-only-at-init, read-only module * parameteters like 'max_loop' and 'max_part' make things needlessly * complicated, are too static, inflexible and may surprise * userspace tools. Parameters like this in general should be avoided. */ if (!part_shift) set_bit(GD_SUPPRESS_PART_SCAN, &disk->state); mutex_init(&lo->lo_mutex); lo->lo_number = i; spin_lock_init(&lo->lo_lock); spin_lock_init(&lo->lo_work_lock); INIT_WORK(&lo->rootcg_work, loop_rootcg_workfn); INIT_LIST_HEAD(&lo->rootcg_cmd_list); disk->major = LOOP_MAJOR; disk->first_minor = i << part_shift; disk->minors = 1 << part_shift; disk->fops = &lo_fops; disk->private_data = lo; disk->queue = lo->lo_queue; disk->events = DISK_EVENT_MEDIA_CHANGE; disk->event_flags = DISK_EVENT_FLAG_UEVENT; sprintf(disk->disk_name, "loop%d", i); /* Make this loop device reachable from pathname. */ err = add_disk(disk); if (err) goto out_cleanup_disk; /* Show this loop device. */ mutex_lock(&loop_ctl_mutex); lo->idr_visible = true; mutex_unlock(&loop_ctl_mutex); return i; out_cleanup_disk: put_disk(disk); out_cleanup_tags: blk_mq_free_tag_set(&lo->tag_set); out_free_idr: mutex_lock(&loop_ctl_mutex); idr_remove(&loop_index_idr, i); mutex_unlock(&loop_ctl_mutex); out_free_dev: kfree(lo); out: return err; } static void loop_remove(struct loop_device *lo) { /* Make this loop device unreachable from pathname. */ del_gendisk(lo->lo_disk); blk_mq_free_tag_set(&lo->tag_set); mutex_lock(&loop_ctl_mutex); idr_remove(&loop_index_idr, lo->lo_number); mutex_unlock(&loop_ctl_mutex); put_disk(lo->lo_disk); } static void loop_probe(dev_t dev) { int idx = MINOR(dev) >> part_shift; if (max_loop && idx >= max_loop) return; loop_add(idx); } static int loop_control_remove(int idx) { struct loop_device *lo; int ret; if (idx < 0) { pr_warn_once("deleting an unspecified loop device is not supported.\n"); return -EINVAL; } /* Hide this loop device for serialization. */ ret = mutex_lock_killable(&loop_ctl_mutex); if (ret) return ret; lo = idr_find(&loop_index_idr, idx); if (!lo || !lo->idr_visible) ret = -ENODEV; else lo->idr_visible = false; mutex_unlock(&loop_ctl_mutex); if (ret) return ret; /* Check whether this loop device can be removed. */ ret = mutex_lock_killable(&lo->lo_mutex); if (ret) goto mark_visible; if (lo->lo_state != Lo_unbound || disk_openers(lo->lo_disk) > 0) { mutex_unlock(&lo->lo_mutex); ret = -EBUSY; goto mark_visible; } /* Mark this loop device as no more bound, but not quite unbound yet */ lo->lo_state = Lo_deleting; mutex_unlock(&lo->lo_mutex); loop_remove(lo); return 0; mark_visible: /* Show this loop device again. */ mutex_lock(&loop_ctl_mutex); lo->idr_visible = true; mutex_unlock(&loop_ctl_mutex); return ret; } static int loop_control_get_free(int idx) { struct loop_device *lo; int id, ret; ret = mutex_lock_killable(&loop_ctl_mutex); if (ret) return ret; idr_for_each_entry(&loop_index_idr, lo, id) { /* Hitting a race results in creating a new loop device which is harmless. */ if (lo->idr_visible && data_race(lo->lo_state) == Lo_unbound) goto found; } mutex_unlock(&loop_ctl_mutex); return loop_add(-1); found: mutex_unlock(&loop_ctl_mutex); return id; } static long loop_control_ioctl(struct file *file, unsigned int cmd, unsigned long parm) { switch (cmd) { case LOOP_CTL_ADD: return loop_add(parm); case LOOP_CTL_REMOVE: return loop_control_remove(parm); case LOOP_CTL_GET_FREE: return loop_control_get_free(parm); default: return -ENOSYS; } } static const struct file_operations loop_ctl_fops = { .open = nonseekable_open, .unlocked_ioctl = loop_control_ioctl, .compat_ioctl = loop_control_ioctl, .owner = THIS_MODULE, .llseek = noop_llseek, }; static struct miscdevice loop_misc = { .minor = LOOP_CTRL_MINOR, .name = "loop-control", .fops = &loop_ctl_fops, }; MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR); MODULE_ALIAS("devname:loop-control"); static int __init loop_init(void) { int i; int err; part_shift = 0; if (max_part > 0) { part_shift = fls(max_part); /* * Adjust max_part according to part_shift as it is exported * to user space so that user can decide correct minor number * if [s]he want to create more devices. * * Note that -1 is required because partition 0 is reserved * for the whole disk. */ max_part = (1UL << part_shift) - 1; } if ((1UL << part_shift) > DISK_MAX_PARTS) { err = -EINVAL; goto err_out; } if (max_loop > 1UL << (MINORBITS - part_shift)) { err = -EINVAL; goto err_out; } err = misc_register(&loop_misc); if (err < 0) goto err_out; if (__register_blkdev(LOOP_MAJOR, "loop", loop_probe)) { err = -EIO; goto misc_out; } /* pre-create number of devices given by config or max_loop */ for (i = 0; i < max_loop; i++) loop_add(i); printk(KERN_INFO "loop: module loaded\n"); return 0; misc_out: misc_deregister(&loop_misc); err_out: return err; } static void __exit loop_exit(void) { struct loop_device *lo; int id; unregister_blkdev(LOOP_MAJOR, "loop"); misc_deregister(&loop_misc); /* * There is no need to use loop_ctl_mutex here, for nobody else can * access loop_index_idr when this module is unloading (unless forced * module unloading is requested). If this is not a clean unloading, * we have no means to avoid kernel crash. */ idr_for_each_entry(&loop_index_idr, lo, id) loop_remove(lo); idr_destroy(&loop_index_idr); } module_init(loop_init); module_exit(loop_exit); #ifndef MODULE static int __init max_loop_setup(char *str) { max_loop = simple_strtol(str, NULL, 0); return 1; } __setup("max_loop=", max_loop_setup); #endif
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