diff options
Diffstat (limited to 'block/bdev.c')
| -rw-r--r-- | block/bdev.c | 1148 |
1 files changed, 1148 insertions, 0 deletions
diff --git a/block/bdev.c b/block/bdev.c new file mode 100644 index 000000000000..e9f1b12bd75c --- /dev/null +++ b/block/bdev.c @@ -0,0 +1,1148 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 1991, 1992 Linus Torvalds + * Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE + * Copyright (C) 2016 - 2020 Christoph Hellwig + */ + +#include <linux/init.h> +#include <linux/mm.h> +#include <linux/slab.h> +#include <linux/kmod.h> +#include <linux/major.h> +#include <linux/device_cgroup.h> +#include <linux/blkdev.h> +#include <linux/blk-integrity.h> +#include <linux/backing-dev.h> +#include <linux/module.h> +#include <linux/blkpg.h> +#include <linux/magic.h> +#include <linux/buffer_head.h> +#include <linux/swap.h> +#include <linux/writeback.h> +#include <linux/mount.h> +#include <linux/pseudo_fs.h> +#include <linux/uio.h> +#include <linux/namei.h> +#include <linux/part_stat.h> +#include <linux/uaccess.h> +#include <linux/stat.h> +#include "../fs/internal.h" +#include "blk.h" + +/* Should we allow writing to mounted block devices? */ +static bool bdev_allow_write_mounted = IS_ENABLED(CONFIG_BLK_DEV_WRITE_MOUNTED); + +struct bdev_inode { + struct block_device bdev; + struct inode vfs_inode; +}; + +static inline struct bdev_inode *BDEV_I(struct inode *inode) +{ + return container_of(inode, struct bdev_inode, vfs_inode); +} + +struct block_device *I_BDEV(struct inode *inode) +{ + return &BDEV_I(inode)->bdev; +} +EXPORT_SYMBOL(I_BDEV); + +static void bdev_write_inode(struct block_device *bdev) +{ + struct inode *inode = bdev->bd_inode; + int ret; + + spin_lock(&inode->i_lock); + while (inode->i_state & I_DIRTY) { + spin_unlock(&inode->i_lock); + ret = write_inode_now(inode, true); + if (ret) + pr_warn_ratelimited( + "VFS: Dirty inode writeback failed for block device %pg (err=%d).\n", + bdev, ret); + spin_lock(&inode->i_lock); + } + spin_unlock(&inode->i_lock); +} + +/* Kill _all_ buffers and pagecache , dirty or not.. */ +static void kill_bdev(struct block_device *bdev) +{ + struct address_space *mapping = bdev->bd_inode->i_mapping; + + if (mapping_empty(mapping)) + return; + + invalidate_bh_lrus(); + truncate_inode_pages(mapping, 0); +} + +/* Invalidate clean unused buffers and pagecache. */ +void invalidate_bdev(struct block_device *bdev) +{ + struct address_space *mapping = bdev->bd_inode->i_mapping; + + if (mapping->nrpages) { + invalidate_bh_lrus(); + lru_add_drain_all(); /* make sure all lru add caches are flushed */ + invalidate_mapping_pages(mapping, 0, -1); + } +} +EXPORT_SYMBOL(invalidate_bdev); + +/* + * Drop all buffers & page cache for given bdev range. This function bails + * with error if bdev has other exclusive owner (such as filesystem). + */ +int truncate_bdev_range(struct block_device *bdev, blk_mode_t mode, + loff_t lstart, loff_t lend) +{ + /* + * If we don't hold exclusive handle for the device, upgrade to it + * while we discard the buffer cache to avoid discarding buffers + * under live filesystem. + */ + if (!(mode & BLK_OPEN_EXCL)) { + int err = bd_prepare_to_claim(bdev, truncate_bdev_range, NULL); + if (err) + goto invalidate; + } + + truncate_inode_pages_range(bdev->bd_inode->i_mapping, lstart, lend); + if (!(mode & BLK_OPEN_EXCL)) + bd_abort_claiming(bdev, truncate_bdev_range); + return 0; + +invalidate: + /* + * Someone else has handle exclusively open. Try invalidating instead. + * The 'end' argument is inclusive so the rounding is safe. + */ + return invalidate_inode_pages2_range(bdev->bd_inode->i_mapping, + lstart >> PAGE_SHIFT, + lend >> PAGE_SHIFT); +} + +static void set_init_blocksize(struct block_device *bdev) +{ + unsigned int bsize = bdev_logical_block_size(bdev); + loff_t size = i_size_read(bdev->bd_inode); + + while (bsize < PAGE_SIZE) { + if (size & bsize) + break; + bsize <<= 1; + } + bdev->bd_inode->i_blkbits = blksize_bits(bsize); +} + +int set_blocksize(struct block_device *bdev, int size) +{ + /* Size must be a power of two, and between 512 and PAGE_SIZE */ + if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size)) + return -EINVAL; + + /* Size cannot be smaller than the size supported by the device */ + if (size < bdev_logical_block_size(bdev)) + return -EINVAL; + + /* Don't change the size if it is same as current */ + if (bdev->bd_inode->i_blkbits != blksize_bits(size)) { + sync_blockdev(bdev); + bdev->bd_inode->i_blkbits = blksize_bits(size); + kill_bdev(bdev); + } + return 0; +} + +EXPORT_SYMBOL(set_blocksize); + +int sb_set_blocksize(struct super_block *sb, int size) +{ + if (set_blocksize(sb->s_bdev, size)) + return 0; + /* If we get here, we know size is power of two + * and it's value is between 512 and PAGE_SIZE */ + sb->s_blocksize = size; + sb->s_blocksize_bits = blksize_bits(size); + return sb->s_blocksize; +} + +EXPORT_SYMBOL(sb_set_blocksize); + +int sb_min_blocksize(struct super_block *sb, int size) +{ + int minsize = bdev_logical_block_size(sb->s_bdev); + if (size < minsize) + size = minsize; + return sb_set_blocksize(sb, size); +} + +EXPORT_SYMBOL(sb_min_blocksize); + +int sync_blockdev_nowait(struct block_device *bdev) +{ + if (!bdev) + return 0; + return filemap_flush(bdev->bd_inode->i_mapping); +} +EXPORT_SYMBOL_GPL(sync_blockdev_nowait); + +/* + * Write out and wait upon all the dirty data associated with a block + * device via its mapping. Does not take the superblock lock. + */ +int sync_blockdev(struct block_device *bdev) +{ + if (!bdev) + return 0; + return filemap_write_and_wait(bdev->bd_inode->i_mapping); +} +EXPORT_SYMBOL(sync_blockdev); + +int sync_blockdev_range(struct block_device *bdev, loff_t lstart, loff_t lend) +{ + return filemap_write_and_wait_range(bdev->bd_inode->i_mapping, + lstart, lend); +} +EXPORT_SYMBOL(sync_blockdev_range); + +/** + * bdev_freeze - lock a filesystem and force it into a consistent state + * @bdev: blockdevice to lock + * + * If a superblock is found on this device, we take the s_umount semaphore + * on it to make sure nobody unmounts until the snapshot creation is done. + * The reference counter (bd_fsfreeze_count) guarantees that only the last + * unfreeze process can unfreeze the frozen filesystem actually when multiple + * freeze requests arrive simultaneously. It counts up in bdev_freeze() and + * count down in bdev_thaw(). When it becomes 0, thaw_bdev() will unfreeze + * actually. + * + * Return: On success zero is returned, negative error code on failure. + */ +int bdev_freeze(struct block_device *bdev) +{ + int error = 0; + + mutex_lock(&bdev->bd_fsfreeze_mutex); + + if (atomic_inc_return(&bdev->bd_fsfreeze_count) > 1) { + mutex_unlock(&bdev->bd_fsfreeze_mutex); + return 0; + } + + mutex_lock(&bdev->bd_holder_lock); + if (bdev->bd_holder_ops && bdev->bd_holder_ops->freeze) { + error = bdev->bd_holder_ops->freeze(bdev); + lockdep_assert_not_held(&bdev->bd_holder_lock); + } else { + mutex_unlock(&bdev->bd_holder_lock); + error = sync_blockdev(bdev); + } + + if (error) + atomic_dec(&bdev->bd_fsfreeze_count); + + mutex_unlock(&bdev->bd_fsfreeze_mutex); + return error; +} +EXPORT_SYMBOL(bdev_freeze); + +/** + * bdev_thaw - unlock filesystem + * @bdev: blockdevice to unlock + * + * Unlocks the filesystem and marks it writeable again after bdev_freeze(). + * + * Return: On success zero is returned, negative error code on failure. + */ +int bdev_thaw(struct block_device *bdev) +{ + int error = -EINVAL, nr_freeze; + + mutex_lock(&bdev->bd_fsfreeze_mutex); + + /* + * If this returns < 0 it means that @bd_fsfreeze_count was + * already 0 and no decrement was performed. + */ + nr_freeze = atomic_dec_if_positive(&bdev->bd_fsfreeze_count); + if (nr_freeze < 0) + goto out; + + error = 0; + if (nr_freeze > 0) + goto out; + + mutex_lock(&bdev->bd_holder_lock); + if (bdev->bd_holder_ops && bdev->bd_holder_ops->thaw) { + error = bdev->bd_holder_ops->thaw(bdev); + lockdep_assert_not_held(&bdev->bd_holder_lock); + } else { + mutex_unlock(&bdev->bd_holder_lock); + } + + if (error) + atomic_inc(&bdev->bd_fsfreeze_count); +out: + mutex_unlock(&bdev->bd_fsfreeze_mutex); + return error; +} +EXPORT_SYMBOL(bdev_thaw); + +/* + * pseudo-fs + */ + +static __cacheline_aligned_in_smp DEFINE_MUTEX(bdev_lock); +static struct kmem_cache *bdev_cachep __ro_after_init; + +static struct inode *bdev_alloc_inode(struct super_block *sb) +{ + struct bdev_inode *ei = alloc_inode_sb(sb, bdev_cachep, GFP_KERNEL); + + if (!ei) + return NULL; + memset(&ei->bdev, 0, sizeof(ei->bdev)); + return &ei->vfs_inode; +} + +static void bdev_free_inode(struct inode *inode) +{ + struct block_device *bdev = I_BDEV(inode); + + free_percpu(bdev->bd_stats); + kfree(bdev->bd_meta_info); + + if (!bdev_is_partition(bdev)) { + if (bdev->bd_disk && bdev->bd_disk->bdi) + bdi_put(bdev->bd_disk->bdi); + kfree(bdev->bd_disk); + } + + if (MAJOR(bdev->bd_dev) == BLOCK_EXT_MAJOR) + blk_free_ext_minor(MINOR(bdev->bd_dev)); + + kmem_cache_free(bdev_cachep, BDEV_I(inode)); +} + +static void init_once(void *data) +{ + struct bdev_inode *ei = data; + + inode_init_once(&ei->vfs_inode); +} + +static void bdev_evict_inode(struct inode *inode) +{ + truncate_inode_pages_final(&inode->i_data); + invalidate_inode_buffers(inode); /* is it needed here? */ + clear_inode(inode); +} + +static const struct super_operations bdev_sops = { + .statfs = simple_statfs, + .alloc_inode = bdev_alloc_inode, + .free_inode = bdev_free_inode, + .drop_inode = generic_delete_inode, + .evict_inode = bdev_evict_inode, +}; + +static int bd_init_fs_context(struct fs_context *fc) +{ + struct pseudo_fs_context *ctx = init_pseudo(fc, BDEVFS_MAGIC); + if (!ctx) + return -ENOMEM; + fc->s_iflags |= SB_I_CGROUPWB; + ctx->ops = &bdev_sops; + return 0; +} + +static struct file_system_type bd_type = { + .name = "bdev", + .init_fs_context = bd_init_fs_context, + .kill_sb = kill_anon_super, +}; + +struct super_block *blockdev_superblock __ro_after_init; +EXPORT_SYMBOL_GPL(blockdev_superblock); + +void __init bdev_cache_init(void) +{ + int err; + static struct vfsmount *bd_mnt __ro_after_init; + + bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode), + 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT| + SLAB_MEM_SPREAD|SLAB_ACCOUNT|SLAB_PANIC), + init_once); + err = register_filesystem(&bd_type); + if (err) + panic("Cannot register bdev pseudo-fs"); + bd_mnt = kern_mount(&bd_type); + if (IS_ERR(bd_mnt)) + panic("Cannot create bdev pseudo-fs"); + blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */ +} + +struct block_device *bdev_alloc(struct gendisk *disk, u8 partno) +{ + struct block_device *bdev; + struct inode *inode; + + inode = new_inode(blockdev_superblock); + if (!inode) + return NULL; + inode->i_mode = S_IFBLK; + inode->i_rdev = 0; + inode->i_data.a_ops = &def_blk_aops; + mapping_set_gfp_mask(&inode->i_data, GFP_USER); + + bdev = I_BDEV(inode); + mutex_init(&bdev->bd_fsfreeze_mutex); + spin_lock_init(&bdev->bd_size_lock); + mutex_init(&bdev->bd_holder_lock); + bdev->bd_partno = partno; + bdev->bd_inode = inode; + bdev->bd_queue = disk->queue; + if (partno) + bdev->bd_has_submit_bio = disk->part0->bd_has_submit_bio; + else + bdev->bd_has_submit_bio = false; + bdev->bd_stats = alloc_percpu(struct disk_stats); + if (!bdev->bd_stats) { + iput(inode); + return NULL; + } + bdev->bd_disk = disk; + return bdev; +} + +void bdev_set_nr_sectors(struct block_device *bdev, sector_t sectors) +{ + spin_lock(&bdev->bd_size_lock); + i_size_write(bdev->bd_inode, (loff_t)sectors << SECTOR_SHIFT); + bdev->bd_nr_sectors = sectors; + spin_unlock(&bdev->bd_size_lock); +} + +void bdev_add(struct block_device *bdev, dev_t dev) +{ + if (bdev_stable_writes(bdev)) + mapping_set_stable_writes(bdev->bd_inode->i_mapping); + bdev->bd_dev = dev; + bdev->bd_inode->i_rdev = dev; + bdev->bd_inode->i_ino = dev; + insert_inode_hash(bdev->bd_inode); +} + +long nr_blockdev_pages(void) +{ + struct inode *inode; + long ret = 0; + + spin_lock(&blockdev_superblock->s_inode_list_lock); + list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) + ret += inode->i_mapping->nrpages; + spin_unlock(&blockdev_superblock->s_inode_list_lock); + + return ret; +} + +/** + * bd_may_claim - test whether a block device can be claimed + * @bdev: block device of interest + * @holder: holder trying to claim @bdev + * @hops: holder ops + * + * Test whether @bdev can be claimed by @holder. + * + * RETURNS: + * %true if @bdev can be claimed, %false otherwise. + */ +static bool bd_may_claim(struct block_device *bdev, void *holder, + const struct blk_holder_ops *hops) +{ + struct block_device *whole = bdev_whole(bdev); + + lockdep_assert_held(&bdev_lock); + + if (bdev->bd_holder) { + /* + * The same holder can always re-claim. + */ + if (bdev->bd_holder == holder) { + if (WARN_ON_ONCE(bdev->bd_holder_ops != hops)) + return false; + return true; + } + return false; + } + + /* + * If the whole devices holder is set to bd_may_claim, a partition on + * the device is claimed, but not the whole device. + */ + if (whole != bdev && + whole->bd_holder && whole->bd_holder != bd_may_claim) + return false; + return true; +} + +/** + * bd_prepare_to_claim - claim a block device + * @bdev: block device of interest + * @holder: holder trying to claim @bdev + * @hops: holder ops. + * + * Claim @bdev. This function fails if @bdev is already claimed by another + * holder and waits if another claiming is in progress. return, the caller + * has ownership of bd_claiming and bd_holder[s]. + * + * RETURNS: + * 0 if @bdev can be claimed, -EBUSY otherwise. + */ +int bd_prepare_to_claim(struct block_device *bdev, void *holder, + const struct blk_holder_ops *hops) +{ + struct block_device *whole = bdev_whole(bdev); + + if (WARN_ON_ONCE(!holder)) + return -EINVAL; +retry: + mutex_lock(&bdev_lock); + /* if someone else claimed, fail */ + if (!bd_may_claim(bdev, holder, hops)) { + mutex_unlock(&bdev_lock); + return -EBUSY; + } + + /* if claiming is already in progress, wait for it to finish */ + if (whole->bd_claiming) { + wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0); + DEFINE_WAIT(wait); + + prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE); + mutex_unlock(&bdev_lock); + schedule(); + finish_wait(wq, &wait); + goto retry; + } + + /* yay, all mine */ + whole->bd_claiming = holder; + mutex_unlock(&bdev_lock); + return 0; +} +EXPORT_SYMBOL_GPL(bd_prepare_to_claim); /* only for the loop driver */ + +static void bd_clear_claiming(struct block_device *whole, void *holder) +{ + lockdep_assert_held(&bdev_lock); + /* tell others that we're done */ + BUG_ON(whole->bd_claiming != holder); + whole->bd_claiming = NULL; + wake_up_bit(&whole->bd_claiming, 0); +} + +/** + * bd_finish_claiming - finish claiming of a block device + * @bdev: block device of interest + * @holder: holder that has claimed @bdev + * @hops: block device holder operations + * + * Finish exclusive open of a block device. Mark the device as exlusively + * open by the holder and wake up all waiters for exclusive open to finish. + */ +static void bd_finish_claiming(struct block_device *bdev, void *holder, + const struct blk_holder_ops *hops) +{ + struct block_device *whole = bdev_whole(bdev); + + mutex_lock(&bdev_lock); + BUG_ON(!bd_may_claim(bdev, holder, hops)); + /* + * Note that for a whole device bd_holders will be incremented twice, + * and bd_holder will be set to bd_may_claim before being set to holder + */ + whole->bd_holders++; + whole->bd_holder = bd_may_claim; + bdev->bd_holders++; + mutex_lock(&bdev->bd_holder_lock); + bdev->bd_holder = holder; + bdev->bd_holder_ops = hops; + mutex_unlock(&bdev->bd_holder_lock); + bd_clear_claiming(whole, holder); + mutex_unlock(&bdev_lock); +} + +/** + * bd_abort_claiming - abort claiming of a block device + * @bdev: block device of interest + * @holder: holder that has claimed @bdev + * + * Abort claiming of a block device when the exclusive open failed. This can be + * also used when exclusive open is not actually desired and we just needed + * to block other exclusive openers for a while. + */ +void bd_abort_claiming(struct block_device *bdev, void *holder) +{ + mutex_lock(&bdev_lock); + bd_clear_claiming(bdev_whole(bdev), holder); + mutex_unlock(&bdev_lock); +} +EXPORT_SYMBOL(bd_abort_claiming); + +static void bd_end_claim(struct block_device *bdev, void *holder) +{ + struct block_device *whole = bdev_whole(bdev); + bool unblock = false; + + /* + * Release a claim on the device. The holder fields are protected with + * bdev_lock. open_mutex is used to synchronize disk_holder unlinking. + */ + mutex_lock(&bdev_lock); + WARN_ON_ONCE(bdev->bd_holder != holder); + WARN_ON_ONCE(--bdev->bd_holders < 0); + WARN_ON_ONCE(--whole->bd_holders < 0); + if (!bdev->bd_holders) { + mutex_lock(&bdev->bd_holder_lock); + bdev->bd_holder = NULL; + bdev->bd_holder_ops = NULL; + mutex_unlock(&bdev->bd_holder_lock); + if (bdev->bd_write_holder) + unblock = true; + } + if (!whole->bd_holders) + whole->bd_holder = NULL; + mutex_unlock(&bdev_lock); + + /* + * If this was the last claim, remove holder link and unblock evpoll if + * it was a write holder. + */ + if (unblock) { + disk_unblock_events(bdev->bd_disk); + bdev->bd_write_holder = false; + } +} + +static void blkdev_flush_mapping(struct block_device *bdev) +{ + WARN_ON_ONCE(bdev->bd_holders); + sync_blockdev(bdev); + kill_bdev(bdev); + bdev_write_inode(bdev); +} + +static int blkdev_get_whole(struct block_device *bdev, blk_mode_t mode) +{ + struct gendisk *disk = bdev->bd_disk; + int ret; + + if (disk->fops->open) { + ret = disk->fops->open(disk, mode); + if (ret) { + /* avoid ghost partitions on a removed medium */ + if (ret == -ENOMEDIUM && + test_bit(GD_NEED_PART_SCAN, &disk->state)) + bdev_disk_changed(disk, true); + return ret; + } + } + + if (!atomic_read(&bdev->bd_openers)) + set_init_blocksize(bdev); + if (test_bit(GD_NEED_PART_SCAN, &disk->state)) + bdev_disk_changed(disk, false); + atomic_inc(&bdev->bd_openers); + return 0; +} + +static void blkdev_put_whole(struct block_device *bdev) +{ + if (atomic_dec_and_test(&bdev->bd_openers)) + blkdev_flush_mapping(bdev); + if (bdev->bd_disk->fops->release) + bdev->bd_disk->fops->release(bdev->bd_disk); +} + +static int blkdev_get_part(struct block_device *part, blk_mode_t mode) +{ + struct gendisk *disk = part->bd_disk; + int ret; + + ret = blkdev_get_whole(bdev_whole(part), mode); + if (ret) + return ret; + + ret = -ENXIO; + if (!bdev_nr_sectors(part)) + goto out_blkdev_put; + + if (!atomic_read(&part->bd_openers)) { + disk->open_partitions++; + set_init_blocksize(part); + } + atomic_inc(&part->bd_openers); + return 0; + +out_blkdev_put: + blkdev_put_whole(bdev_whole(part)); + return ret; +} + +static void blkdev_put_part(struct block_device *part) +{ + struct block_device *whole = bdev_whole(part); + + if (atomic_dec_and_test(&part->bd_openers)) { + blkdev_flush_mapping(part); + whole->bd_disk->open_partitions--; + } + blkdev_put_whole(whole); +} + +struct block_device *blkdev_get_no_open(dev_t dev) +{ + struct block_device *bdev; + struct inode *inode; + + inode = ilookup(blockdev_superblock, dev); + if (!inode && IS_ENABLED(CONFIG_BLOCK_LEGACY_AUTOLOAD)) { + blk_request_module(dev); + inode = ilookup(blockdev_superblock, dev); + if (inode) + pr_warn_ratelimited( +"block device autoloading is deprecated and will be removed.\n"); + } + if (!inode) + return NULL; + + /* switch from the inode reference to a device mode one: */ + bdev = &BDEV_I(inode)->bdev; + if (!kobject_get_unless_zero(&bdev->bd_device.kobj)) + bdev = NULL; + iput(inode); + return bdev; +} + +void blkdev_put_no_open(struct block_device *bdev) +{ + put_device(&bdev->bd_device); +} + +static bool bdev_writes_blocked(struct block_device *bdev) +{ + return bdev->bd_writers == -1; +} + +static void bdev_block_writes(struct block_device *bdev) +{ + bdev->bd_writers = -1; +} + +static void bdev_unblock_writes(struct block_device *bdev) +{ + bdev->bd_writers = 0; +} + +static bool bdev_may_open(struct block_device *bdev, blk_mode_t mode) +{ + if (bdev_allow_write_mounted) + return true; + /* Writes blocked? */ + if (mode & BLK_OPEN_WRITE && bdev_writes_blocked(bdev)) + return false; + if (mode & BLK_OPEN_RESTRICT_WRITES && bdev->bd_writers > 0) + return false; + return true; +} + +static void bdev_claim_write_access(struct block_device *bdev, blk_mode_t mode) +{ + if (bdev_allow_write_mounted) + return; + + /* Claim exclusive or shared write access. */ + if (mode & BLK_OPEN_RESTRICT_WRITES) + bdev_block_writes(bdev); + else if (mode & BLK_OPEN_WRITE) + bdev->bd_writers++; +} + +static void bdev_yield_write_access(struct block_device *bdev, blk_mode_t mode) +{ + if (bdev_allow_write_mounted) + return; + + /* Yield exclusive or shared write access. */ + if (mode & BLK_OPEN_RESTRICT_WRITES) + bdev_unblock_writes(bdev); + else if (mode & BLK_OPEN_WRITE) + bdev->bd_writers--; +} + +/** + * bdev_open_by_dev - open a block device by device number + * @dev: device number of block device to open + * @mode: open mode (BLK_OPEN_*) + * @holder: exclusive holder identifier + * @hops: holder operations + * + * Open the block device described by device number @dev. If @holder is not + * %NULL, the block device is opened with exclusive access. Exclusive opens may + * nest for the same @holder. + * + * Use this interface ONLY if you really do not have anything better - i.e. when + * you are behind a truly sucky interface and all you are given is a device + * number. Everything else should use bdev_open_by_path(). + * + * CONTEXT: + * Might sleep. + * + * RETURNS: + * Handle with a reference to the block_device on success, ERR_PTR(-errno) on + * failure. + */ +struct bdev_handle *bdev_open_by_dev(dev_t dev, blk_mode_t mode, void *holder, + const struct blk_holder_ops *hops) +{ + struct bdev_handle *handle = kmalloc(sizeof(struct bdev_handle), + GFP_KERNEL); + struct block_device *bdev; + bool unblock_events = true; + struct gendisk *disk; + int ret; + + if (!handle) + return ERR_PTR(-ENOMEM); + + ret = devcgroup_check_permission(DEVCG_DEV_BLOCK, + MAJOR(dev), MINOR(dev), + ((mode & BLK_OPEN_READ) ? DEVCG_ACC_READ : 0) | + ((mode & BLK_OPEN_WRITE) ? DEVCG_ACC_WRITE : 0)); + if (ret) + goto free_handle; + + /* Blocking writes requires exclusive opener */ + if (mode & BLK_OPEN_RESTRICT_WRITES && !holder) { + ret = -EINVAL; + goto free_handle; + } + + bdev = blkdev_get_no_open(dev); + if (!bdev) { + ret = -ENXIO; + goto free_handle; + } + disk = bdev->bd_disk; + + if (holder) { + mode |= BLK_OPEN_EXCL; + ret = bd_prepare_to_claim(bdev, holder, hops); + if (ret) + goto put_blkdev; + } else { + if (WARN_ON_ONCE(mode & BLK_OPEN_EXCL)) { + ret = -EIO; + goto put_blkdev; + } + } + + disk_block_events(disk); + + mutex_lock(&disk->open_mutex); + ret = -ENXIO; + if (!disk_live(disk)) + goto abort_claiming; + if (!try_module_get(disk->fops->owner)) + goto abort_claiming; + ret = -EBUSY; + if (!bdev_may_open(bdev, mode)) + goto abort_claiming; + if (bdev_is_partition(bdev)) + ret = blkdev_get_part(bdev, mode); + else + ret = blkdev_get_whole(bdev, mode); + if (ret) + goto put_module; + bdev_claim_write_access(bdev, mode); + if (holder) { + bd_finish_claiming(bdev, holder, hops); + + /* + * Block event polling for write claims if requested. Any write + * holder makes the write_holder state stick until all are + * released. This is good enough and tracking individual + * writeable reference is too fragile given the way @mode is + * used in blkdev_get/put(). + */ + if ((mode & BLK_OPEN_WRITE) && !bdev->bd_write_holder && + (disk->event_flags & DISK_EVENT_FLAG_BLOCK_ON_EXCL_WRITE)) { + bdev->bd_write_holder = true; + unblock_events = false; + } + } + mutex_unlock(&disk->open_mutex); + + if (unblock_events) + disk_unblock_events(disk); + handle->bdev = bdev; + handle->holder = holder; + handle->mode = mode; + return handle; +put_module: + module_put(disk->fops->owner); +abort_claiming: + if (holder) + bd_abort_claiming(bdev, holder); + mutex_unlock(&disk->open_mutex); + disk_unblock_events(disk); +put_blkdev: + blkdev_put_no_open(bdev); +free_handle: + kfree(handle); + return ERR_PTR(ret); +} +EXPORT_SYMBOL(bdev_open_by_dev); + +/** + * bdev_open_by_path - open a block device by name + * @path: path to the block device to open + * @mode: open mode (BLK_OPEN_*) + * @holder: exclusive holder identifier + * @hops: holder operations + * + * Open the block device described by the device file at @path. If @holder is + * not %NULL, the block device is opened with exclusive access. Exclusive opens + * may nest for the same @holder. + * + * CONTEXT: + * Might sleep. + * + * RETURNS: + * Handle with a reference to the block_device on success, ERR_PTR(-errno) on + * failure. + */ +struct bdev_handle *bdev_open_by_path(const char *path, blk_mode_t mode, + void *holder, const struct blk_holder_ops *hops) +{ + struct bdev_handle *handle; + dev_t dev; + int error; + + error = lookup_bdev(path, &dev); + if (error) + return ERR_PTR(error); + + handle = bdev_open_by_dev(dev, mode, holder, hops); + if (!IS_ERR(handle) && (mode & BLK_OPEN_WRITE) && + bdev_read_only(handle->bdev)) { + bdev_release(handle); + return ERR_PTR(-EACCES); + } + + return handle; +} +EXPORT_SYMBOL(bdev_open_by_path); + +void bdev_release(struct bdev_handle *handle) +{ + struct block_device *bdev = handle->bdev; + struct gendisk *disk = bdev->bd_disk; + + /* + * Sync early if it looks like we're the last one. If someone else + * opens the block device between now and the decrement of bd_openers + * then we did a sync that we didn't need to, but that's not the end + * of the world and we want to avoid long (could be several minute) + * syncs while holding the mutex. + */ + if (atomic_read(&bdev->bd_openers) == 1) + sync_blockdev(bdev); + + mutex_lock(&disk->open_mutex); + bdev_yield_write_access(bdev, handle->mode); + + if (handle->holder) + bd_end_claim(bdev, handle->holder); + + /* + * Trigger event checking and tell drivers to flush MEDIA_CHANGE + * event. This is to ensure detection of media removal commanded + * from userland - e.g. eject(1). + */ + disk_flush_events(disk, DISK_EVENT_MEDIA_CHANGE); + + if (bdev_is_partition(bdev)) + blkdev_put_part(bdev); + else + blkdev_put_whole(bdev); + mutex_unlock(&disk->open_mutex); + + module_put(disk->fops->owner); + blkdev_put_no_open(bdev); + kfree(handle); +} +EXPORT_SYMBOL(bdev_release); + +/** + * lookup_bdev() - Look up a struct block_device by name. + * @pathname: Name of the block device in the filesystem. + * @dev: Pointer to the block device's dev_t, if found. + * + * Lookup the block device's dev_t at @pathname in the current + * namespace if possible and return it in @dev. + * + * Context: May sleep. + * Return: 0 if succeeded, negative errno otherwise. + */ +int lookup_bdev(const char *pathname, dev_t *dev) +{ + struct inode *inode; + struct path path; + int error; + + if (!pathname || !*pathname) + return -EINVAL; + + error = kern_path(pathname, LOOKUP_FOLLOW, &path); + if (error) + return error; + + inode = d_backing_inode(path.dentry); + error = -ENOTBLK; + if (!S_ISBLK(inode->i_mode)) + goto out_path_put; + error = -EACCES; + if (!may_open_dev(&path)) + goto out_path_put; + + *dev = inode->i_rdev; + error = 0; +out_path_put: + path_put(&path); + return error; +} +EXPORT_SYMBOL(lookup_bdev); + +/** + * bdev_mark_dead - mark a block device as dead + * @bdev: block device to operate on + * @surprise: indicate a surprise removal + * + * Tell the file system that this devices or media is dead. If @surprise is set + * to %true the device or media is already gone, if not we are preparing for an + * orderly removal. + * + * This calls into the file system, which then typicall syncs out all dirty data + * and writes back inodes and then invalidates any cached data in the inodes on + * the file system. In addition we also invalidate the block device mapping. + */ +void bdev_mark_dead(struct block_device *bdev, bool surprise) +{ + mutex_lock(&bdev->bd_holder_lock); + if (bdev->bd_holder_ops && bdev->bd_holder_ops->mark_dead) + bdev->bd_holder_ops->mark_dead(bdev, surprise); + else { + mutex_unlock(&bdev->bd_holder_lock); + sync_blockdev(bdev); + } + + invalidate_bdev(bdev); +} +/* + * New drivers should not use this directly. There are some drivers however + * that needs this for historical reasons. For example, the DASD driver has + * historically had a shutdown to offline mode that doesn't actually remove the + * gendisk that otherwise looks a lot like a safe device removal. + */ +EXPORT_SYMBOL_GPL(bdev_mark_dead); + +void sync_bdevs(bool wait) +{ + struct inode *inode, *old_inode = NULL; + + spin_lock(&blockdev_superblock->s_inode_list_lock); + list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) { + struct address_space *mapping = inode->i_mapping; + struct block_device *bdev; + + spin_lock(&inode->i_lock); + if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) || + mapping->nrpages == 0) { + spin_unlock(&inode->i_lock); + continue; + } + __iget(inode); + spin_unlock(&inode->i_lock); + spin_unlock(&blockdev_superblock->s_inode_list_lock); + /* + * We hold a reference to 'inode' so it couldn't have been + * removed from s_inodes list while we dropped the + * s_inode_list_lock We cannot iput the inode now as we can + * be holding the last reference and we cannot iput it under + * s_inode_list_lock. So we keep the reference and iput it + * later. + */ + iput(old_inode); + old_inode = inode; + bdev = I_BDEV(inode); + + mutex_lock(&bdev->bd_disk->open_mutex); + if (!atomic_read(&bdev->bd_openers)) { + ; /* skip */ + } else if (wait) { + /* + * We keep the error status of individual mapping so + * that applications can catch the writeback error using + * fsync(2). See filemap_fdatawait_keep_errors() for + * details. + */ + filemap_fdatawait_keep_errors(inode->i_mapping); + } else { + filemap_fdatawrite(inode->i_mapping); + } + mutex_unlock(&bdev->bd_disk->open_mutex); + + spin_lock(&blockdev_superblock->s_inode_list_lock); + } + spin_unlock(&blockdev_superblock->s_inode_list_lock); + iput(old_inode); +} + +/* + * Handle STATX_DIOALIGN for block devices. + * + * Note that the inode passed to this is the inode of a block device node file, + * not the block device's internal inode. Therefore it is *not* valid to use + * I_BDEV() here; the block device has to be looked up by i_rdev instead. + */ +void bdev_statx_dioalign(struct inode *inode, struct kstat *stat) +{ + struct block_device *bdev; + + bdev = blkdev_get_no_open(inode->i_rdev); + if (!bdev) + return; + + stat->dio_mem_align = bdev_dma_alignment(bdev) + 1; + stat->dio_offset_align = bdev_logical_block_size(bdev); + stat->result_mask |= STATX_DIOALIGN; + + blkdev_put_no_open(bdev); +} + +static int __init setup_bdev_allow_write_mounted(char *str) +{ + if (kstrtobool(str, &bdev_allow_write_mounted)) + pr_warn("Invalid option string for bdev_allow_write_mounted:" + " '%s'\n", str); + return 1; +} +__setup("bdev_allow_write_mounted=", setup_bdev_allow_write_mounted); |