Commit 0718afd4 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

block: introduce holder ops 



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: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Acked-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Link: https://lore.kernel.org/r/20230601094459.1350643-10-hch@lst.de


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 00080f7f

block/bdev.c

+29 −12
Original line number Diff line number Diff line
@@ -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);

block/fops.c

+1 −1
Original line number Diff line number Diff line
@@ -490,7 +490,7 @@ static int blkdev_open(struct inode *inode, struct file *filp) 
	if ((filp->f_flags & O_ACCMODE) == 3)

		filp->f_mode |= FMODE_WRITE_IOCTL;



	bdev = blkdev_get_by_dev(inode->i_rdev, filp->f_mode, filp);

	bdev = blkdev_get_by_dev(inode->i_rdev, filp->f_mode, filp, NULL);

	if (IS_ERR(bdev))

		return PTR_ERR(bdev);

block/genhd.c

+4 −2
Original line number Diff line number Diff line
@@ -370,13 +370,15 @@ int disk_scan_partitions(struct gendisk *disk, fmode_t mode) 
	 * scanners.

	 */

	if (!(mode & FMODE_EXCL)) {

		ret = bd_prepare_to_claim(disk->part0, disk_scan_partitions);

		ret = bd_prepare_to_claim(disk->part0, disk_scan_partitions,

					  NULL);

		if (ret)

			return ret;

	}



	set_bit(GD_NEED_PART_SCAN, &disk->state);

	bdev = blkdev_get_by_dev(disk_devt(disk), mode & ~FMODE_EXCL, NULL);

	bdev = blkdev_get_by_dev(disk_devt(disk), mode & ~FMODE_EXCL, NULL,

				 NULL);

	if (IS_ERR(bdev))

		ret =  PTR_ERR(bdev);

	else

block/ioctl.c

+2 −1
Original line number Diff line number Diff line
@@ -454,7 +454,8 @@ static int blkdev_bszset(struct block_device *bdev, fmode_t mode, 
	if (mode & FMODE_EXCL)

		return set_blocksize(bdev, n);



	if (IS_ERR(blkdev_get_by_dev(bdev->bd_dev, mode | FMODE_EXCL, &bdev)))

	if (IS_ERR(blkdev_get_by_dev(bdev->bd_dev, mode | FMODE_EXCL, &bdev,

			NULL)))

		return -EBUSY;

	ret = set_blocksize(bdev, n);

	blkdev_put(bdev, mode | FMODE_EXCL);

drivers/block/drbd/drbd_nl.c

+2 −1
Original line number Diff line number Diff line
@@ -1641,7 +1641,8 @@ static struct block_device *open_backing_dev(struct drbd_device *device, 
	int err = 0;



	bdev = blkdev_get_by_path(bdev_path,

				  FMODE_READ | FMODE_WRITE | FMODE_EXCL, claim_ptr);

				  FMODE_READ | FMODE_WRITE | FMODE_EXCL,

				  claim_ptr, NULL);

	if (IS_ERR(bdev)) {

		drbd_err(device, "open(\"%s\") failed with %ld\n",

				bdev_path, PTR_ERR(bdev));