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authorDavid Sterba <dsterba@suse.com>2018-08-24 17:32:29 +0200
committerDavid Sterba <dsterba@suse.com>2018-10-15 17:23:37 +0200
commit3280f874576d31b03fe19cbcc23585d96feb4ceb (patch)
treef94ff5ae016c6ca99f75c5ae2de455c065d75730
parentf556faa46eb4e96d0d0772e74ecf66781e132f72 (diff)
btrfs: remove btrfs_dev_replace::read_locks
This member seems to be copied from the extent_buffer locking scheme and is at least used to assert that the read lock/unlock is properly nested. In some way. While the _inc/_dec are called inside the read lock section, the asserts are both inside and outside, so the ordering is not guaranteed and we can see read/inc/dec ordered in any way (theoretically). A missing call of btrfs_dev_replace_clear_lock_blocking could cause unexpected read_locks count, so this at least looks like a valid assertion, but this will become unnecessary with later updates. Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
-rw-r--r--fs/btrfs/ctree.h1
-rw-r--r--fs/btrfs/dev-replace.c5
-rw-r--r--fs/btrfs/disk-io.c1
3 files changed, 0 insertions, 7 deletions
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 36ade217e462..daa273c7e150 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -361,7 +361,6 @@ struct btrfs_dev_replace {
struct mutex lock_finishing_cancel_unmount;
rwlock_t lock;
- atomic_t read_locks;
atomic_t blocking_readers;
wait_queue_head_t read_lock_wq;
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index ff01740158aa..702fe6a65075 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -964,13 +964,10 @@ int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
void btrfs_dev_replace_read_lock(struct btrfs_dev_replace *dev_replace)
{
read_lock(&dev_replace->lock);
- atomic_inc(&dev_replace->read_locks);
}
void btrfs_dev_replace_read_unlock(struct btrfs_dev_replace *dev_replace)
{
- ASSERT(atomic_read(&dev_replace->read_locks) > 0);
- atomic_dec(&dev_replace->read_locks);
read_unlock(&dev_replace->lock);
}
@@ -997,7 +994,6 @@ void btrfs_dev_replace_set_lock_blocking(
struct btrfs_dev_replace *dev_replace)
{
/* only set blocking for read lock */
- ASSERT(atomic_read(&dev_replace->read_locks) > 0);
atomic_inc(&dev_replace->blocking_readers);
read_unlock(&dev_replace->lock);
}
@@ -1007,7 +1003,6 @@ void btrfs_dev_replace_clear_lock_blocking(
struct btrfs_dev_replace *dev_replace)
{
/* only set blocking for read lock */
- ASSERT(atomic_read(&dev_replace->read_locks) > 0);
ASSERT(atomic_read(&dev_replace->blocking_readers) > 0);
read_lock(&dev_replace->lock);
/* Barrier implied by atomic_dec_and_test */
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 517484ecad96..79903243877b 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2155,7 +2155,6 @@ static void btrfs_init_dev_replace_locks(struct btrfs_fs_info *fs_info)
{
mutex_init(&fs_info->dev_replace.lock_finishing_cancel_unmount);
rwlock_init(&fs_info->dev_replace.lock);
- atomic_set(&fs_info->dev_replace.read_locks, 0);
atomic_set(&fs_info->dev_replace.blocking_readers, 0);
init_waitqueue_head(&fs_info->replace_wait);
init_waitqueue_head(&fs_info->dev_replace.read_lock_wq);