diff options
Diffstat (limited to 'drivers/block/loop.c')
| -rw-r--r-- | drivers/block/loop.c | 2355 |
1 files changed, 2355 insertions, 0 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c new file mode 100644 index 000000000..6f1297603 --- /dev/null +++ b/drivers/block/loop.c @@ -0,0 +1,2355 @@ +// 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_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; + unsigned int lo_min_dio_size; + unsigned int lo_dio_mem_align; + 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 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 lo_calculate_size(struct loop_device *lo, struct file *file) +{ + loff_t loopsize; + int ret; + + if (S_ISBLK(file_inode(file)->i_mode)) { + loopsize = i_size_read(file->f_mapping->host); + } else { + struct kstat stat; + + /* + * Get the accurate file size. This provides better results than + * cached inode data, particularly for network filesystems where + * metadata may be stale. + */ + ret = vfs_getattr_nosec(&file->f_path, &stat, STATX_SIZE, 0); + if (ret) + return 0; + + loopsize = stat.size; + } + + if (lo->lo_offset > 0) + loopsize -= lo->lo_offset; + /* offset is beyond i_size, weird but possible */ + if (loopsize < 0) + return 0; + if (lo->lo_sizelimit > 0 && lo->lo_sizelimit < loopsize) + loopsize = lo->lo_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; +} + +/* + * 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 that of + * the backing device. + */ +static bool lo_can_use_dio(struct loop_device *lo) +{ + if (!(lo->lo_backing_file->f_mode & FMODE_CAN_ODIRECT)) + return false; + if (queue_logical_block_size(lo->lo_queue) < lo->lo_min_dio_size) + return false; + if (lo->lo_offset & (lo->lo_min_dio_size - 1)) + return false; + return true; +} + +/* + * Direct I/O can be enabled either by using an O_DIRECT file descriptor, or by + * passing in the LO_FLAGS_DIRECT_IO flag from userspace. It will be silently + * disabled when the device block size is too small or the offset is unaligned. + * + * loop_get_status will always report the effective LO_FLAGS_DIRECT_IO flag and + * not the originally passed in one. + */ +static inline void loop_update_dio(struct loop_device *lo) +{ + lockdep_assert_held(&lo->lo_mutex); + WARN_ON_ONCE(lo->lo_state == Lo_bound && + lo->lo_queue->mq_freeze_depth == 0); + + if ((lo->lo_flags & LO_FLAGS_DIRECT_IO) && !lo_can_use_dio(lo)) + lo->lo_flags &= ~LO_FLAGS_DIRECT_IO; +} + +/** + * 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 void loop_clear_limits(struct loop_device *lo, int mode) +{ + struct queue_limits lim = queue_limits_start_update(lo->lo_queue); + + if (mode & FALLOC_FL_ZERO_RANGE) + lim.max_write_zeroes_sectors = 0; + + if (mode & FALLOC_FL_PUNCH_HOLE) { + lim.max_hw_discard_sectors = 0; + lim.discard_granularity = 0; + } + + /* + * XXX: this updates the queue limits without freezing the queue, which + * is against the locking protocol and dangerous. But we can't just + * freeze the queue as we're inside the ->queue_rq method here. So this + * should move out into a workqueue unless we get the file operations to + * advertise if they support specific fallocate operations. + */ + queue_limits_commit_update(lo->lo_queue, &lim); +} + +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; + + /* + * We initially configure the limits in a hope that fallocate is + * supported and clear them here if that turns out not to be true. + */ + if (unlikely(ret == -EOPNOTSUPP)) + loop_clear_limits(lo, mode); + + 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->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 { + 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 (req_op(rq) == REQ_OP_WRITE) + kiocb_end_write(&cmd->iocb); + 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 request *rq = blk_mq_rq_from_pdu(cmd); + struct file *file = lo->lo_backing_file; + unsigned int nr_bvec; + int ret; + + nr_bvec = blk_rq_nr_bvec(rq); + + if (rq->bio != rq->biotail) { + struct bio_vec tmp, *bvec; + + cmd->bvec = kmalloc_objs(*cmd->bvec, nr_bvec, GFP_NOIO); + if (!cmd->bvec) + return -EIO; + + /* + * 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. + */ + bvec = cmd->bvec; + rq_for_each_bvec(tmp, rq, rq_iter) { + *bvec = tmp; + bvec++; + } + iov_iter_bvec(&iter, rw, cmd->bvec, nr_bvec, blk_rq_bytes(rq)); + iter.iov_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 + */ + iov_iter_bvec(&iter, rw, + __bvec_iter_bvec(rq->bio->bi_io_vec, rq->bio->bi_iter), + nr_bvec, blk_rq_bytes(rq)); + iter.iov_offset = rq->bio->bi_iter.bi_offset; + } + atomic_set(&cmd->ref, 2); + + cmd->iocb.ki_pos = pos; + cmd->iocb.ki_filp = file; + cmd->iocb.ki_ioprio = req_get_ioprio(rq); + if (cmd->use_aio) { + cmd->iocb.ki_complete = lo_rw_aio_complete; + cmd->iocb.ki_flags = IOCB_DIRECT; + } else { + cmd->iocb.ki_complete = NULL; + cmd->iocb.ki_flags = 0; + } + + if (rw == ITER_SOURCE) { + kiocb_start_write(&cmd->iocb); + ret = file->f_op->write_iter(&cmd->iocb, &iter); + } else + ret = file->f_op->read_iter(&cmd->iocb, &iter); + + lo_rw_aio_do_completion(cmd); + + if (ret != -EIOCBQUEUED) + lo_rw_aio_complete(&cmd->iocb, ret); + return -EIOCBQUEUED; +} + +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; + + 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: + return lo_rw_aio(lo, cmd, pos, ITER_SOURCE); + case REQ_OP_READ: + return lo_rw_aio(lo, cmd, pos, ITER_DEST); + default: + WARN_ON_ONCE(1); + return -EIO; + } +} + +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 void loop_update_dio_alignment(struct loop_device *lo) +{ + struct file *file = lo->lo_backing_file; + struct block_device *sb_bdev = file->f_mapping->host->i_sb->s_bdev; + struct kstat st; + + /* + * Use the dio alignment of the file system if provided. The incomoing + * request's bio_vec is forwarded to the backing file unchanged, so its + * required memory alignment becomes the device's dma_alignment when + * used for direct-io. + */ + if (!vfs_getattr(&file->f_path, &st, STATX_DIOALIGN, 0) && + (st.result_mask & STATX_DIOALIGN)) { + lo->lo_min_dio_size = st.dio_offset_align; + lo->lo_dio_mem_align = st.dio_mem_align - 1; + return; + } + + /* + * In a perfect world this wouldn't be needed, but as of Linux 6.13 only + * a handful of file systems support the STATX_DIOALIGN flag. + */ + if (sb_bdev) { + lo->lo_min_dio_size = bdev_logical_block_size(sb_bdev); + lo->lo_dio_mem_align = bdev_dma_alignment(sb_bdev); + return; + } + + lo->lo_min_dio_size = SECTOR_SIZE; + lo->lo_dio_mem_align = SECTOR_SIZE - 1; +} + +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; +} + +static void loop_assign_backing_file(struct loop_device *lo, struct file *file) +{ + 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)); + if (lo->lo_backing_file->f_flags & O_DIRECT) + lo->lo_flags |= LO_FLAGS_DIRECT_IO; + loop_update_dio_alignment(lo); +} + +static int loop_check_backing_file(struct file *file) +{ + if (!file->f_op->read_iter) + return -EINVAL; + + if ((file->f_mode & FMODE_WRITE) && !file->f_op->write_iter) + 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; + unsigned int memflags; + int error; + bool partscan; + bool is_loop; + + if (!file) + return -EBADF; + + error = loop_check_backing_file(file); + if (error) { + fput(file); + return error; + } + + /* 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 (lo_calculate_size(lo, file) != lo_calculate_size(lo, old_file)) + goto out_err; + + /* + * We might switch to direct I/O mode for the loop device, write back + * all dirty data the page cache now that so that the individual I/O + * operations don't have to do that. + */ + vfs_fsync(file, 0); + + /* and ... switch */ + disk_force_media_change(lo->lo_disk); + memflags = blk_mq_freeze_queue(lo->lo_queue); + mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask); + loop_assign_backing_file(lo, file); + loop_update_dio(lo); + blk_mq_unfreeze_queue(lo->lo_queue, memflags); + 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); + dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0); + if (partscan) + loop_reread_partitions(lo); + + error = 0; +done: + kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE); + return error; + +out_err: + loop_global_unlock(lo, is_loop); +out_putf: + fput(file); + dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0); + 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_get_discard_config(struct loop_device *lo, + u32 *granularity, u32 *max_discard_sectors) +{ + struct file *file = lo->lo_backing_file; + struct inode *inode = file->f_mapping->host; + struct kstatfs sbuf; + + /* + * 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 block_device *bdev = I_BDEV(inode); + + *max_discard_sectors = bdev_write_zeroes_sectors(bdev); + *granularity = bdev_discard_granularity(bdev); + + /* + * We use punch hole to reclaim the free space used by the + * image a.k.a. discard. + */ + } else if (file->f_op->fallocate && !vfs_statfs(&file->f_path, &sbuf)) { + *max_discard_sectors = UINT_MAX >> 9; + *granularity = sbuf.f_bsize; + } +} + +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_obj(struct loop_worker, GFP_NOWAIT); + /* + * 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); +} + +/** + * 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; + return 0; +} + +static unsigned int loop_default_blocksize(struct loop_device *lo) +{ + /* In case of direct I/O, match underlying minimum I/O size */ + if (lo->lo_flags & LO_FLAGS_DIRECT_IO) + return lo->lo_min_dio_size; + return SECTOR_SIZE; +} + +static void loop_set_dma_limit(struct loop_device *lo, struct queue_limits *lim) +{ + /* + * Direct I/O forwards the user pages to the backing file unchanged, so + * track the backing's DMA alignment requirement as the mode is toggled. + */ + if (lo->lo_flags & LO_FLAGS_DIRECT_IO) + lim->dma_alignment = max_t(unsigned int, lo->lo_dio_mem_align, + SECTOR_SIZE - 1); + else + lim->dma_alignment = SECTOR_SIZE - 1; +} + +static void loop_update_limits(struct loop_device *lo, struct queue_limits *lim, + unsigned int bsize) +{ + struct file *file = lo->lo_backing_file; + struct inode *inode = file->f_mapping->host; + struct block_device *backing_bdev = NULL; + u32 granularity = 0, max_discard_sectors = 0; + + if (S_ISBLK(inode->i_mode)) + backing_bdev = I_BDEV(inode); + else if (inode->i_sb->s_bdev) + backing_bdev = inode->i_sb->s_bdev; + + if (!bsize) + bsize = loop_default_blocksize(lo); + + loop_get_discard_config(lo, &granularity, &max_discard_sectors); + + lim->logical_block_size = bsize; + lim->physical_block_size = bsize; + lim->io_min = bsize; + loop_set_dma_limit(lo, lim); + lim->features &= ~(BLK_FEAT_WRITE_CACHE | BLK_FEAT_ROTATIONAL); + if (file->f_op->fsync && !(lo->lo_flags & LO_FLAGS_READ_ONLY)) + lim->features |= BLK_FEAT_WRITE_CACHE; + if (backing_bdev && bdev_rot(backing_bdev)) + lim->features |= BLK_FEAT_ROTATIONAL; + lim->max_hw_discard_sectors = max_discard_sectors; + lim->max_write_zeroes_sectors = max_discard_sectors; + if (max_discard_sectors) + lim->discard_granularity = granularity; + else + lim->discard_granularity = 0; +} + +static int loop_configure(struct loop_device *lo, blk_mode_t mode, + struct block_device *bdev, + const struct loop_config *config) +{ + struct file *file = fget(config->fd); + struct queue_limits lim; + int error; + loff_t size; + bool partscan; + bool is_loop; + + if (!file) + return -EBADF; + + error = loop_check_backing_file(file); + if (error) { + fput(file); + return error; + } + + 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 & BLK_OPEN_EXCL)) { + error = bd_prepare_to_claim(bdev, loop_configure, NULL); + 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; + + if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) { + error = -EINVAL; + goto out_unlock; + } + + error = loop_set_status_from_info(lo, &config->info); + if (error) + goto out_unlock; + lo->lo_flags = config->info.lo_flags; + + if (!(file->f_mode & FMODE_WRITE) || !(mode & BLK_OPEN_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); + set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0); + + lo->lo_device = bdev; + loop_assign_backing_file(lo, file); + + lim = queue_limits_start_update(lo->lo_queue); + loop_update_limits(lo, &lim, config->block_size); + /* No need to freeze the queue as the device isn't bound yet. */ + error = queue_limits_commit_update(lo->lo_queue, &lim); + if (error) + goto out_unlock; + + /* + * We might switch to direct I/O mode for the loop device, write back + * all dirty data the page cache now that so that the individual I/O + * operations don't have to do that. + */ + vfs_fsync(file, 0); + + loop_update_dio(lo); + loop_sysfs_init(lo); + + size = lo_calculate_size(lo, file); + loop_set_size(lo, size); + + /* Order wrt reading lo_state in loop_validate_file(). */ + wmb(); + + WRITE_ONCE(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); + + dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0); + kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE); + + loop_global_unlock(lo, is_loop); + if (partscan) + loop_reread_partitions(lo); + + if (!(mode & BLK_OPEN_EXCL)) + bd_abort_claiming(bdev, loop_configure); + + return 0; + +out_unlock: + loop_global_unlock(lo, is_loop); +out_bdev: + if (!(mode & BLK_OPEN_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) +{ + struct queue_limits lim; + struct file *filp; + gfp_t gfp = lo->old_gfp_mask; + int err; + + 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); + + /* + * Reset the block size to the default. + * + * No queue freezing needed because this is called from the final + * ->release call only, so there can't be any outstanding I/O. + */ + lim = queue_limits_start_update(lo->lo_queue); + lim.logical_block_size = SECTOR_SIZE; + lim.physical_block_size = SECTOR_SIZE; + lim.io_min = SECTOR_SIZE; + queue_limits_commit_update(lo->lo_queue, &lim); + + 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); + + disk_force_media_change(lo->lo_disk); + + /* + * Remove all partitions, including partitions added manually with + * BLKPG, which may exist even if LO_FLAGS_PARTSCAN is not set. + * + * open_mutex has been held already in release path, so don't acquire + * it here. + */ + err = bdev_disk_changed(lo->lo_disk, false); + 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 removing partitions 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); + WRITE_ONCE(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; + } + /* + * Mark the device for removing the backing device on last close. + * If we are the only opener, also switch the state to roundown here to + * prevent new openers from coming in. + */ + + lo->lo_flags |= LO_FLAGS_AUTOCLEAR; + if (disk_openers(lo->lo_disk) == 1) + WRITE_ONCE(lo->lo_state, Lo_rundown); + loop_global_unlock(lo, true); + + return 0; +} + +static int +loop_set_status(struct loop_device *lo, const struct loop_info64 *info) +{ + int err; + bool partscan = false; + bool size_changed = false; + unsigned int memflags; + + 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 needs to be drained before changing lo_offset or lo_sizelimit */ + memflags = blk_mq_freeze_queue(lo->lo_queue); + + err = loop_set_status_from_info(lo, info); + if (err) + goto out_unfreeze; + + partscan = !(lo->lo_flags & LO_FLAGS_PARTSCAN) && + (info->lo_flags & LO_FLAGS_PARTSCAN); + + lo->lo_flags &= ~LOOP_SET_STATUS_CLEARABLE_FLAGS; + lo->lo_flags |= (info->lo_flags & LOOP_SET_STATUS_SETTABLE_FLAGS); + + /* update the direct I/O flag if lo_offset changed */ + loop_update_dio(lo); + +out_unfreeze: + blk_mq_unfreeze_queue(lo->lo_queue, memflags); + if (partscan) + clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state); + if (!err && size_changed) { + loff_t new_size = lo_calculate_size(lo, lo->lo_backing_file); + loop_set_size(lo, new_size); + } +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 = lo_calculate_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) +{ + bool use_dio = !!arg; + unsigned int memflags; + struct queue_limits lim; + + if (lo->lo_state != Lo_bound) + return -ENXIO; + if (use_dio == !!(lo->lo_flags & LO_FLAGS_DIRECT_IO)) + return 0; + + if (use_dio) { + if (!lo_can_use_dio(lo)) + return -EINVAL; + /* flush dirty pages before starting to use direct I/O */ + vfs_fsync(lo->lo_backing_file, 0); + } + + lim = queue_limits_start_update(lo->lo_queue); + memflags = blk_mq_freeze_queue(lo->lo_queue); + if (use_dio) + lo->lo_flags |= LO_FLAGS_DIRECT_IO; + else + lo->lo_flags &= ~LO_FLAGS_DIRECT_IO; + loop_set_dma_limit(lo, &lim); + queue_limits_commit_update(lo->lo_queue, &lim); + blk_mq_unfreeze_queue(lo->lo_queue, memflags); + return 0; +} + +static int loop_set_block_size(struct loop_device *lo, blk_mode_t mode, + struct block_device *bdev, unsigned long arg) +{ + struct queue_limits lim; + unsigned int memflags; + int err = 0; + + /* + * If we don't hold exclusive handle for the device, upgrade to it + * here to avoid changing device under exclusive owner. + */ + if (!(mode & BLK_OPEN_EXCL)) { + err = bd_prepare_to_claim(bdev, loop_set_block_size, NULL); + if (err) + return err; + } + + err = mutex_lock_killable(&lo->lo_mutex); + if (err) + goto abort_claim; + + if (lo->lo_state != Lo_bound) { + err = -ENXIO; + goto unlock; + } + + if (lo->lo_queue->limits.logical_block_size == arg) + goto unlock; + + sync_blockdev(lo->lo_device); + invalidate_bdev(lo->lo_device); + + lim = queue_limits_start_update(lo->lo_queue); + loop_update_limits(lo, &lim, arg); + + memflags = blk_mq_freeze_queue(lo->lo_queue); + err = queue_limits_commit_update(lo->lo_queue, &lim); + loop_update_dio(lo); + blk_mq_unfreeze_queue(lo->lo_queue, memflags); + +unlock: + mutex_unlock(&lo->lo_mutex); +abort_claim: + if (!(mode & BLK_OPEN_EXCL)) + bd_abort_claiming(bdev, loop_set_block_size); + 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; + default: + err = -EINVAL; + } + mutex_unlock(&lo->lo_mutex); + return err; +} + +static int lo_ioctl(struct block_device *bdev, blk_mode_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 & BLK_OPEN_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 & BLK_OPEN_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_BLOCK_SIZE: + if (!(mode & BLK_OPEN_WRITE) && !capable(CAP_SYS_ADMIN)) + return -EPERM; + return loop_set_block_size(lo, mode, bdev, arg); + case LOOP_SET_CAPACITY: + case LOOP_SET_DIRECT_IO: + if (!(mode & BLK_OPEN_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, blk_mode_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 int lo_open(struct gendisk *disk, blk_mode_t mode) +{ + struct loop_device *lo = disk->private_data; + int err; + + err = mutex_lock_killable(&lo->lo_mutex); + if (err) + return err; + + if (lo->lo_state == Lo_deleting || lo->lo_state == Lo_rundown) + err = -ENXIO; + mutex_unlock(&lo->lo_mutex); + return err; +} + +static void lo_release(struct gendisk *disk) +{ + struct loop_device *lo = disk->private_data; + bool need_clear = false; + + if (disk_openers(disk) > 0) + return; + /* + * Clear the backing device information if this is the last close of + * a device that's been marked for auto clear, or on which LOOP_CLR_FD + * has been called. + */ + + mutex_lock(&lo->lo_mutex); + if (lo->lo_state == Lo_bound && (lo->lo_flags & LO_FLAGS_AUTOCLEAR)) + WRITE_ONCE(lo->lo_state, Lo_rundown); + + need_clear = (lo->lo_state == Lo_rundown); + mutex_unlock(&lo->lo_mutex); + + if (need_clear) + __loop_clr_fd(lo); +} + +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, + .open = lo_open, + .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, + * the default isn't a hard limit (as before commit 85c50197716c + * changed the default value from 0 for max_loop=0 reasons), just + * 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; + +#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD +static bool max_loop_specified; + +static int max_loop_param_set_int(const char *val, + const struct kernel_param *kp) +{ + int ret; + + ret = param_set_int(val, kp); + if (ret < 0) + return ret; + + max_loop_specified = true; + return 0; +} + +static const struct kernel_param_ops max_loop_param_ops = { + .set = max_loop_param_set_int, + .get = param_get_int, +}; + +module_param_cb(max_loop, &max_loop_param_ops, &max_loop, 0444); +MODULE_PARM_DESC(max_loop, "Maximum number of loop devices"); +#else +module_param(max_loop, int, 0444); +MODULE_PARM_DESC(max_loop, "Initial number of loop devices"); +#endif + +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_DESCRIPTION("Loopback device support"); +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 (data_race(READ_ONCE(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->lo_flags & LO_FLAGS_DIRECT_IO; + 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; + + if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) { + ret = -EIO; + goto failed; + } + + /* We can block in this context, so ignore REQ_NOWAIT. */ + if (rq->cmd_flags & REQ_NOWAIT) + rq->cmd_flags &= ~REQ_NOWAIT; + + 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 (ret != -EIOCBQUEUED) { + 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 queue_limits lim = { + /* + * Random number picked from the historic block max_sectors cap. + */ + .max_hw_sectors = 2560u, + }; + struct loop_device *lo; + struct gendisk *disk; + int err; + + err = -ENOMEM; + lo = kzalloc_obj(*lo); + 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); + WRITE_ONCE(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_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, &lim, lo); + if (IS_ERR(disk)) { + err = PTR_ERR(disk); + goto out_cleanup_tags; + } + lo->lo_queue = lo->lo_disk->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); +} + +#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD +static void loop_probe(dev_t dev) +{ + int idx = MINOR(dev) >> part_shift; + + if (max_loop_specified && max_loop && idx >= max_loop) + return; + loop_add(idx); +} +#else +#define loop_probe NULL +#endif /* !CONFIG_BLOCK_LEGACY_AUTOLOAD */ + +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 */ + WRITE_ONCE(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(READ_ONCE(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); +#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD + max_loop_specified = true; +#endif + return 1; +} + +__setup("max_loop=", max_loop_setup); +#endif |