[PATCH 05/13] 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>
---
block/bdev.c | 16 ++++++++--------
block/partitions/core.c | 2 +-
include/linux/blk_types.h | 2 +-
include/linux/blkdev.h | 2 +-
4 files changed, 11 insertions(+), 11 deletions(-)
diff --git a/block/bdev.c b/block/bdev.c
index 13de871fa8169..7bf88e591aaf3 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) {
/*
diff --git a/block/partitions/core.c b/block/partitions/core.c
index 2ef8dfa1e5c85..373ed748dcf26 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -486,7 +486,7 @@ int bdev_del_partition(struct gendisk *disk, int partno)
goto out_unlock;
ret = -EBUSY;
- if (part->bd_openers)
+ if (atomic_read(&part->bd_openers))
goto out_unlock;
delete_partition(part);
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 0c3563b45fe90..b1ced43ed0d3f 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -44,7 +44,7 @@ struct block_device {
unsigned long bd_stamp;
bool bd_read_only; /* read-only policy */
dev_t bd_dev;
- int bd_openers;
+ atomic_t bd_openers;
struct inode * bd_inode; /* will die */
struct super_block * bd_super;
void * bd_claiming;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 9824ebc9b4d31..6b7c5af1d01df 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -188,7 +188,7 @@ static inline bool disk_live(struct gendisk *disk)
*/
static inline unsigned int disk_openers(struct gendisk *disk)
{
- return disk->part0->bd_openers;
+ return atomic_read(&disk->part0->bd_openers);
}
/*
--
2.30.2
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