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authorChristoph Hellwig <hch@lst.de>2022-03-30 08:29:07 +0300
committerJens Axboe <axboe@kernel.dk>2022-04-18 15:54:09 +0300
commit9acf381f3e8f715175c29f4b6d722f6b6797d139 (patch)
tree9f0a39c15820a6772d4cd0b60f458010b5ac6c64 /block/bdev.c
parentdbdc1be32591af023db2812706f01e6cd2f42bfc (diff)
downloadlinux-9acf381f3e8f715175c29f4b6d722f6b6797d139.tar.xz
block: turn bdev->bd_openers into an atomic_t
All manipulation of bd_openers is under disk->open_mutex and will remain so for the foreseeable future. But at least one place reads it without the lock (blkdev_get) and there are more to be added. So make sure the compiler does not do turn the increments and decrements into non-atomic sequences by using an atomic_t. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20220330052917.2566582-6-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/bdev.c')
-rw-r--r--block/bdev.c16
1 files changed, 8 insertions, 8 deletions
diff --git a/block/bdev.c b/block/bdev.c
index 13de871fa816..7bf88e591aaf 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -673,17 +673,17 @@ static int blkdev_get_whole(struct block_device *bdev, fmode_t mode)
}
}
- if (!bdev->bd_openers)
+ if (!atomic_read(&bdev->bd_openers))
set_init_blocksize(bdev);
if (test_bit(GD_NEED_PART_SCAN, &disk->state))
bdev_disk_changed(disk, false);
- bdev->bd_openers++;
+ atomic_inc(&bdev->bd_openers);
return 0;
}
static void blkdev_put_whole(struct block_device *bdev, fmode_t mode)
{
- if (!--bdev->bd_openers)
+ 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);
@@ -694,7 +694,7 @@ static int blkdev_get_part(struct block_device *part, fmode_t mode)
struct gendisk *disk = part->bd_disk;
int ret;
- if (part->bd_openers)
+ if (atomic_read(&part->bd_openers))
goto done;
ret = blkdev_get_whole(bdev_whole(part), mode);
@@ -708,7 +708,7 @@ static int blkdev_get_part(struct block_device *part, fmode_t mode)
disk->open_partitions++;
set_init_blocksize(part);
done:
- part->bd_openers++;
+ atomic_inc(&part->bd_openers);
return 0;
out_blkdev_put:
@@ -720,7 +720,7 @@ static void blkdev_put_part(struct block_device *part, fmode_t mode)
{
struct block_device *whole = bdev_whole(part);
- if (--part->bd_openers)
+ if (!atomic_dec_and_test(&part->bd_openers))
return;
blkdev_flush_mapping(part);
whole->bd_disk->open_partitions--;
@@ -899,7 +899,7 @@ void blkdev_put(struct block_device *bdev, fmode_t mode)
* of the world and we want to avoid long (could be several minute)
* syncs while holding the mutex.
*/
- if (bdev->bd_openers == 1)
+ if (atomic_read(&bdev->bd_openers) == 1)
sync_blockdev(bdev);
mutex_lock(&disk->open_mutex);
@@ -1044,7 +1044,7 @@ void sync_bdevs(bool wait)
bdev = I_BDEV(inode);
mutex_lock(&bdev->bd_disk->open_mutex);
- if (!bdev->bd_openers) {
+ if (!atomic_read(&bdev->bd_openers)) {
; /* skip */
} else if (wait) {
/*