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block: introduce holder ops

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Add a new blk_holder_ops structure, which is passed to blkdev_get_by_* and
installed in the block_device for exclusive claims.  It will be used to
allow the block layer to call back into the user of the block device for
thing like notification of a removed device or a device resize.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20230601094459.1350643-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig
2023-06-01 11:44:52 +02:00
committed by Jens Axboe
parent 00080f7fb7
commit 0718afd47f
34 changed files with 90 additions and 56 deletions
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41
block/bdev.c
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@@ -102,7 +102,7 @@ int truncate_bdev_range(struct block_device *bdev, fmode_t mode,
* under live filesystem.
*/
if (!(mode & FMODE_EXCL)) {
int err = bd_prepare_to_claim(bdev, truncate_bdev_range);
int err = bd_prepare_to_claim(bdev, truncate_bdev_range, NULL);
if (err)
goto invalidate;
}
@@ -415,6 +415,7 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
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;
@@ -464,13 +465,15 @@ long nr_blockdev_pages(void)
* 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)
static bool bd_may_claim(struct block_device *bdev, void *holder,
const struct blk_holder_ops *hops)
{
struct block_device *whole = bdev_whole(bdev);
@@ -480,8 +483,11 @@ static bool bd_may_claim(struct block_device *bdev, void *holder)
/*
* The same holder can always re-claim.
*/
if (bdev->bd_holder == holder)
if (bdev->bd_holder == holder) {
if (WARN_ON_ONCE(bdev->bd_holder_ops != hops))
return false;
return true;
}
return false;
}
@@ -499,6 +505,7 @@ static bool bd_may_claim(struct block_device *bdev, void *holder)
* 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
@@ -507,7 +514,8 @@ static bool bd_may_claim(struct block_device *bdev, void *holder)
* RETURNS:
* 0 if @bdev can be claimed, -EBUSY otherwise.
*/
int bd_prepare_to_claim(struct block_device *bdev, void *holder)
int bd_prepare_to_claim(struct block_device *bdev, void *holder,
const struct blk_holder_ops *hops)
{
struct block_device *whole = bdev_whole(bdev);
@@ -516,7 +524,7 @@ int bd_prepare_to_claim(struct block_device *bdev, void *holder)
retry:
mutex_lock(&bdev_lock);
/* if someone else claimed, fail */
if (!bd_may_claim(bdev, holder)) {
if (!bd_may_claim(bdev, holder, hops)) {
mutex_unlock(&bdev_lock);
return -EBUSY;
}
@@ -557,12 +565,13 @@ static void bd_clear_claiming(struct block_device *whole, void *holder)
* 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)
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));
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
@@ -570,7 +579,10 @@ static void bd_finish_claiming(struct block_device *bdev, void *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);
}
@@ -605,7 +617,10 @@ static void bd_end_claim(struct block_device *bdev)
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;
}
@@ -735,6 +750,7 @@ void blkdev_put_no_open(struct block_device *bdev)
* @dev: device number of block device to open
* @mode: FMODE_* mask
* @holder: exclusive holder identifier
* @hops: holder operations
*
* Open the block device described by device number @dev. If @mode includes
* %FMODE_EXCL, the block device is opened with exclusive access. Specifying
@@ -751,7 +767,8 @@ void blkdev_put_no_open(struct block_device *bdev)
* 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)
struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder,
const struct blk_holder_ops *hops)
{
bool unblock_events = true;
struct block_device *bdev;
@@ -771,7 +788,7 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
disk = bdev->bd_disk;
if (mode & FMODE_EXCL) {
ret = bd_prepare_to_claim(bdev, holder);
ret = bd_prepare_to_claim(bdev, holder, hops);
if (ret)
goto put_blkdev;
}
@@ -791,7 +808,7 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
if (ret)
goto put_module;
if (mode & FMODE_EXCL) {
bd_finish_claiming(bdev, holder);
bd_finish_claiming(bdev, holder, hops);
/*
* Block event polling for write claims if requested. Any write
@@ -842,7 +859,7 @@ EXPORT_SYMBOL(blkdev_get_by_dev);
* 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)
void *holder, const struct blk_holder_ops *hops)
{
struct block_device *bdev;
dev_t dev;
@@ -852,7 +869,7 @@ struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
if (error)
return ERR_PTR(error);
bdev = blkdev_get_by_dev(dev, mode, holder);
bdev = blkdev_get_by_dev(dev, mode, holder, hops);
if (!IS_ERR(bdev) && (mode & FMODE_WRITE) && bdev_read_only(bdev)) {
blkdev_put(bdev, mode);
return ERR_PTR(-EACCES);