linux/block/bdev.c
Christoph Hellwig 3222d8c2a7 block: remove ->rw_page
The ->rw_page method is a special purpose bypass of the usual bio handling
path that is limited to single-page reads and writes and synchronous which
causes a lot of extra code in the drivers, callers and the block layer.

The only remaining user is the MM swap code.  Switch that swap code to
simply submit a single-vec on-stack bio an synchronously wait on it based
on a newly added QUEUE_FLAG_SYNCHRONOUS flag set by the drivers that
currently implement ->rw_page instead.  While this touches one extra cache
line and executes extra code, it simplifies the block layer and drivers
and ensures that all feastures are properly supported by all drivers, e.g.
right now ->rw_page bypassed cgroup writeback entirely.

[akpm@linux-foundation.org: fix comment typo, per Dan]
Link: https://lkml.kernel.org/r/20230125133436.447864-8-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Keith Busch <kbusch@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-02 22:33:34 -08:00

1017 lines
25 KiB
C

// 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"
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, fmode_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 & FMODE_EXCL)) {
int err = bd_prepare_to_claim(bdev, truncate_bdev_range);
if (err)
goto invalidate;
}
truncate_inode_pages_range(bdev->bd_inode->i_mapping, lstart, lend);
if (!(mode & FMODE_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);
/*
* Write out and wait upon all dirty data associated with this
* device. Filesystem data as well as the underlying block
* device. Takes the superblock lock.
*/
int fsync_bdev(struct block_device *bdev)
{
struct super_block *sb = get_super(bdev);
if (sb) {
int res = sync_filesystem(sb);
drop_super(sb);
return res;
}
return sync_blockdev(bdev);
}
EXPORT_SYMBOL(fsync_bdev);
/**
* freeze_bdev - 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 freeze_bdev() and
* count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
* actually.
*/
int freeze_bdev(struct block_device *bdev)
{
struct super_block *sb;
int error = 0;
mutex_lock(&bdev->bd_fsfreeze_mutex);
if (++bdev->bd_fsfreeze_count > 1)
goto done;
sb = get_active_super(bdev);
if (!sb)
goto sync;
if (sb->s_op->freeze_super)
error = sb->s_op->freeze_super(sb);
else
error = freeze_super(sb);
deactivate_super(sb);
if (error) {
bdev->bd_fsfreeze_count--;
goto done;
}
bdev->bd_fsfreeze_sb = sb;
sync:
sync_blockdev(bdev);
done:
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return error;
}
EXPORT_SYMBOL(freeze_bdev);
/**
* thaw_bdev - unlock filesystem
* @bdev: blockdevice to unlock
*
* Unlocks the filesystem and marks it writeable again after freeze_bdev().
*/
int thaw_bdev(struct block_device *bdev)
{
struct super_block *sb;
int error = -EINVAL;
mutex_lock(&bdev->bd_fsfreeze_mutex);
if (!bdev->bd_fsfreeze_count)
goto out;
error = 0;
if (--bdev->bd_fsfreeze_count > 0)
goto out;
sb = bdev->bd_fsfreeze_sb;
if (!sb)
goto out;
if (sb->s_op->thaw_super)
error = sb->s_op->thaw_super(sb);
else
error = thaw_super(sb);
if (error)
bdev->bd_fsfreeze_count++;
else
bdev->bd_fsfreeze_sb = NULL;
out:
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return error;
}
EXPORT_SYMBOL(thaw_bdev);
/*
* pseudo-fs
*/
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
static struct kmem_cache * bdev_cachep __read_mostly;
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 __read_mostly;
EXPORT_SYMBOL_GPL(blockdev_superblock);
void __init bdev_cache_init(void)
{
int err;
static struct vfsmount *bd_mnt;
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);
bdev->bd_partno = partno;
bdev->bd_inode = inode;
bdev->bd_queue = disk->queue;
bdev->bd_stats = alloc_percpu(struct disk_stats);
if (!bdev->bd_stats) {
iput(inode);
return NULL;
}
bdev->bd_disk = disk;
return bdev;
}
void bdev_add(struct block_device *bdev, dev_t dev)
{
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
* @whole: whole block device containing @bdev, may equal @bdev
* @holder: holder trying to claim @bdev
*
* Test whether @bdev can be claimed by @holder.
*
* CONTEXT:
* spin_lock(&bdev_lock).
*
* RETURNS:
* %true if @bdev can be claimed, %false otherwise.
*/
static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
void *holder)
{
if (bdev->bd_holder == holder)
return true; /* already a holder */
else if (bdev->bd_holder != NULL)
return false; /* held by someone else */
else if (whole == bdev)
return true; /* is a whole device which isn't held */
else if (whole->bd_holder == bd_may_claim)
return true; /* is a partition of a device that is being partitioned */
else if (whole->bd_holder != NULL)
return false; /* is a partition of a held device */
else
return true; /* is a partition of an un-held device */
}
/**
* bd_prepare_to_claim - claim a block device
* @bdev: block device of interest
* @holder: holder trying to claim @bdev
*
* 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)
{
struct block_device *whole = bdev_whole(bdev);
if (WARN_ON_ONCE(!holder))
return -EINVAL;
retry:
spin_lock(&bdev_lock);
/* if someone else claimed, fail */
if (!bd_may_claim(bdev, whole, holder)) {
spin_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);
spin_unlock(&bdev_lock);
schedule();
finish_wait(wq, &wait);
goto retry;
}
/* yay, all mine */
whole->bd_claiming = holder;
spin_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
*
* 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)
{
struct block_device *whole = bdev_whole(bdev);
spin_lock(&bdev_lock);
BUG_ON(!bd_may_claim(bdev, whole, holder));
/*
* 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++;
bdev->bd_holder = holder;
bd_clear_claiming(whole, holder);
spin_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)
{
spin_lock(&bdev_lock);
bd_clear_claiming(bdev_whole(bdev), holder);
spin_unlock(&bdev_lock);
}
EXPORT_SYMBOL(bd_abort_claiming);
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, fmode_t mode)
{
struct gendisk *disk = bdev->bd_disk;
int ret;
if (disk->fops->open) {
ret = disk->fops->open(bdev, 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, fmode_t mode)
{
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, mode);
}
static int blkdev_get_part(struct block_device *part, fmode_t mode)
{
struct gendisk *disk = part->bd_disk;
int ret;
if (atomic_read(&part->bd_openers))
goto done;
ret = blkdev_get_whole(bdev_whole(part), mode);
if (ret)
return ret;
ret = -ENXIO;
if (!bdev_nr_sectors(part))
goto out_blkdev_put;
disk->open_partitions++;
set_init_blocksize(part);
done:
atomic_inc(&part->bd_openers);
return 0;
out_blkdev_put:
blkdev_put_whole(bdev_whole(part), mode);
return ret;
}
static void blkdev_put_part(struct block_device *part, fmode_t mode)
{
struct block_device *whole = bdev_whole(part);
if (!atomic_dec_and_test(&part->bd_openers))
return;
blkdev_flush_mapping(part);
whole->bd_disk->open_partitions--;
blkdev_put_whole(whole, mode);
}
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);
}
/**
* blkdev_get_by_dev - open a block device by device number
* @dev: device number of block device to open
* @mode: FMODE_* mask
* @holder: exclusive holder identifier
*
* Open the block device described by device number @dev. If @mode includes
* %FMODE_EXCL, the block device is opened with exclusive access. Specifying
* %FMODE_EXCL with a %NULL @holder is invalid. 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 blkdev_get_by_path().
*
* CONTEXT:
* Might sleep.
*
* RETURNS:
* Reference to the block_device on success, ERR_PTR(-errno) on failure.
*/
struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
{
bool unblock_events = true;
struct block_device *bdev;
struct gendisk *disk;
int ret;
ret = devcgroup_check_permission(DEVCG_DEV_BLOCK,
MAJOR(dev), MINOR(dev),
((mode & FMODE_READ) ? DEVCG_ACC_READ : 0) |
((mode & FMODE_WRITE) ? DEVCG_ACC_WRITE : 0));
if (ret)
return ERR_PTR(ret);
bdev = blkdev_get_no_open(dev);
if (!bdev)
return ERR_PTR(-ENXIO);
disk = bdev->bd_disk;
if (mode & FMODE_EXCL) {
ret = bd_prepare_to_claim(bdev, holder);
if (ret)
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;
if (bdev_is_partition(bdev))
ret = blkdev_get_part(bdev, mode);
else
ret = blkdev_get_whole(bdev, mode);
if (ret)
goto put_module;
if (mode & FMODE_EXCL) {
bd_finish_claiming(bdev, holder);
/*
* 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 & FMODE_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);
return bdev;
put_module:
module_put(disk->fops->owner);
abort_claiming:
if (mode & FMODE_EXCL)
bd_abort_claiming(bdev, holder);
mutex_unlock(&disk->open_mutex);
disk_unblock_events(disk);
put_blkdev:
blkdev_put_no_open(bdev);
return ERR_PTR(ret);
}
EXPORT_SYMBOL(blkdev_get_by_dev);
/**
* blkdev_get_by_path - open a block device by name
* @path: path to the block device to open
* @mode: FMODE_* mask
* @holder: exclusive holder identifier
*
* Open the block device described by the device file at @path. If @mode
* includes %FMODE_EXCL, the block device is opened with exclusive access.
* Specifying %FMODE_EXCL with a %NULL @holder is invalid. Exclusive opens may
* nest for the same @holder.
*
* CONTEXT:
* Might sleep.
*
* RETURNS:
* Reference to the block_device on success, ERR_PTR(-errno) on failure.
*/
struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
void *holder)
{
struct block_device *bdev;
dev_t dev;
int error;
error = lookup_bdev(path, &dev);
if (error)
return ERR_PTR(error);
bdev = blkdev_get_by_dev(dev, mode, holder);
if (!IS_ERR(bdev) && (mode & FMODE_WRITE) && bdev_read_only(bdev)) {
blkdev_put(bdev, mode);
return ERR_PTR(-EACCES);
}
return bdev;
}
EXPORT_SYMBOL(blkdev_get_by_path);
void blkdev_put(struct block_device *bdev, fmode_t mode)
{
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);
if (mode & FMODE_EXCL) {
struct block_device *whole = bdev_whole(bdev);
bool bdev_free;
/*
* Release a claim on the device. The holder fields
* are protected with bdev_lock. open_mutex is to
* synchronize disk_holder unlinking.
*/
spin_lock(&bdev_lock);
WARN_ON_ONCE(--bdev->bd_holders < 0);
WARN_ON_ONCE(--whole->bd_holders < 0);
if ((bdev_free = !bdev->bd_holders))
bdev->bd_holder = NULL;
if (!whole->bd_holders)
whole->bd_holder = NULL;
spin_unlock(&bdev_lock);
/*
* If this was the last claim, remove holder link and
* unblock evpoll if it was a write holder.
*/
if (bdev_free && bdev->bd_write_holder) {
disk_unblock_events(disk);
bdev->bd_write_holder = false;
}
}
/*
* 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, mode);
else
blkdev_put_whole(bdev, mode);
mutex_unlock(&disk->open_mutex);
module_put(disk->fops->owner);
blkdev_put_no_open(bdev);
}
EXPORT_SYMBOL(blkdev_put);
/**
* 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);
int __invalidate_device(struct block_device *bdev, bool kill_dirty)
{
struct super_block *sb = get_super(bdev);
int res = 0;
if (sb) {
/*
* no need to lock the super, get_super holds the
* read mutex so the filesystem cannot go away
* under us (->put_super runs with the write lock
* hold).
*/
shrink_dcache_sb(sb);
res = invalidate_inodes(sb, kill_dirty);
drop_super(sb);
}
invalidate_bdev(bdev);
return res;
}
EXPORT_SYMBOL(__invalidate_device);
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);
}