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btrfs: remove btrfs_dev_replace::read_locks

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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>
This commit is contained in:
David Sterba
2018-08-24 17:32:29 +02:00
parent f556faa46e
commit 3280f87457
3 changed files with 0 additions and 7 deletions
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5
fs/btrfs/dev-replace.c
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@@ -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 */