[PATCH 27/45] block: simplify the block device claiming interface

Christoph Hellwig
2020-11-28T22:11:08Z

Stop passing the whole device as a separate argument given that it
can be trivially deducted and cleanup the !holder debug check.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
---
drivers/block/loop.c | 12 +++++-----
fs/block_dev.c | 51 +++++++++++++++---------------------------
include/linux/blkdev.h | 6 ++---
3 files changed, 25 insertions(+), 44 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index c0df88b3300c41..d643c67be6acea 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1069,7 +1069,6 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
struct file *file;
struct inode *inode;
struct address_space *mapping;
- struct block_device *claimed_bdev = NULL;
int error;
loff_t size;
bool partscan;
@@ -1088,8 +1087,7 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
* here to avoid changing device under exclusive owner.
*/
if (!(mode & FMODE_EXCL)) {
- claimed_bdev = bdev_whole(bdev);
- error = bd_prepare_to_claim(bdev, claimed_bdev, loop_configure);
+ error = bd_prepare_to_claim(bdev, loop_configure);
if (error)
goto out_putf;
}
@@ -1176,15 +1174,15 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
mutex_unlock(&loop_ctl_mutex);
if (partscan)
loop_reread_partitions(lo, bdev);
- if (claimed_bdev)
- bd_abort_claiming(bdev, claimed_bdev, loop_configure);
+ if (!(mode & FMODE_EXCL))
+ bd_abort_claiming(bdev, loop_configure);
return 0;

out_unlock:
mutex_unlock(&loop_ctl_mutex);
out_bdev:
- if (claimed_bdev)
- bd_abort_claiming(bdev, claimed_bdev, loop_configure);
+ if (!(mode & FMODE_EXCL))
+ bd_abort_claiming(bdev, loop_configure);
out_putf:
fput(file);
out:
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 94baee369d26e5..0569f5ebeb6fd0 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -110,24 +110,20 @@ EXPORT_SYMBOL(invalidate_bdev);
int truncate_bdev_range(struct block_device *bdev, fmode_t mode,
loff_t lstart, loff_t lend)
{
- struct block_device *claimed_bdev = NULL;
- int err;
-
/*
* 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)) {
- claimed_bdev = bdev_whole(bdev);
- err = bd_prepare_to_claim(bdev, claimed_bdev,
- truncate_bdev_range);
+ int err = bd_prepare_to_claim(bdev, truncate_bdev_range);
if (err)
return err;
}
+
truncate_inode_pages_range(bdev->bd_inode->i_mapping, lstart, lend);
- if (claimed_bdev)
- bd_abort_claiming(bdev, claimed_bdev, truncate_bdev_range);
+ if (!(mode & FMODE_EXCL))
+ bd_abort_claiming(bdev, truncate_bdev_range);
return 0;
}
EXPORT_SYMBOL(truncate_bdev_range);
@@ -978,7 +974,6 @@ static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
/**
* bd_prepare_to_claim - claim a block device
* @bdev: block device of interest
- * @whole: the whole device containing @bdev, may equal @bdev
* @holder: holder trying to claim @bdev
*
* Claim @bdev. This function fails if @bdev is already claimed by another
@@ -988,9 +983,12 @@ static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
* RETURNS:
* 0 if @bdev can be claimed, -EBUSY otherwise.
*/
-int bd_prepare_to_claim(struct block_device *bdev, struct block_device *whole,
- void *holder)
+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 */
@@ -1030,15 +1028,15 @@ static void bd_clear_claiming(struct block_device *whole, void *holder)
/**
* bd_finish_claiming - finish claiming of a block device
* @bdev: block device of interest
- * @whole: whole block device
* @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,
- struct block_device *whole, void *holder)
+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));
/*
@@ -1063,11 +1061,10 @@ static void bd_finish_claiming(struct block_device *bdev,
* 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, struct block_device *whole,
- void *holder)
+void bd_abort_claiming(struct block_device *bdev, void *holder)
{
spin_lock(&bdev_lock);
- bd_clear_claiming(whole, holder);
+ bd_clear_claiming(bdev_whole(bdev), holder);
spin_unlock(&bdev_lock);
}
EXPORT_SYMBOL(bd_abort_claiming);
@@ -1487,7 +1484,6 @@ void blkdev_put_no_open(struct block_device *bdev)
*/
struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
{
- struct block_device *claiming;
bool unblock_events = true;
struct block_device *bdev;
struct gendisk *disk;
@@ -1510,15 +1506,9 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
disk = bdev->bd_disk;

if (mode & FMODE_EXCL) {
- WARN_ON_ONCE(!holder);
-
- ret = -ENOMEM;
- claiming = bdget_disk(disk, 0);
- if (!claiming)
- goto put_blkdev;
- ret = bd_prepare_to_claim(bdev, claiming, holder);
+ ret = bd_prepare_to_claim(bdev, holder);
if (ret)
- goto put_claiming;
+ goto put_blkdev;
}

disk_block_events(disk);
@@ -1528,7 +1518,7 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
if (ret)
goto abort_claiming;
if (mode & FMODE_EXCL) {
- bd_finish_claiming(bdev, claiming, holder);
+ bd_finish_claiming(bdev, holder);

/*
* Block event polling for write claims if requested. Any write
@@ -1547,18 +1537,13 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)

if (unblock_events)
disk_unblock_events(disk);
- if (mode & FMODE_EXCL)
- bdput(claiming);
return bdev;

abort_claiming:
if (mode & FMODE_EXCL)
- bd_abort_claiming(bdev, claiming, holder);
+ bd_abort_claiming(bdev, holder);
mutex_unlock(&bdev->bd_mutex);
disk_unblock_events(disk);
-put_claiming:
- if (mode & FMODE_EXCL)
- bdput(claiming);
put_blkdev:
blkdev_put_no_open(bdev);
if (ret == -ERESTARTSYS)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 5d48b92f5e4348..43a25d855e049a 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1988,10 +1988,8 @@ void blkdev_show(struct seq_file *seqf, off_t offset);
struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
void *holder);
struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder);
-int bd_prepare_to_claim(struct block_device *bdev, struct block_device *whole,
- void *holder);
-void bd_abort_claiming(struct block_device *bdev, struct block_device *whole,
- void *holder);
+int bd_prepare_to_claim(struct block_device *bdev, void *holder);
+void bd_abort_claiming(struct block_device *bdev, void *holder);
void blkdev_put(struct block_device *bdev, fmode_t mode);

/* just for blk-cgroup, don't use elsewhere */
--
2.29.2