Btrfs: Use a mutex in the extent buffer for tree block locking
This replaces the use of the page cache lock bit for locking, which wasn't
suitable for block size < page size and couldn't be used recursively.
The mutexes alone don't fix either problem, but they are the first step.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 058a506..01a9ac2 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -29,32 +29,31 @@
{
int i;
- if (!TestSetPageLocked(eb->first_page))
+ if (mutex_trylock(&eb->mutex))
return 0;
for (i = 0; i < 512; i++) {
cpu_relax();
- if (!TestSetPageLocked(eb->first_page))
+ if (mutex_trylock(&eb->mutex))
return 0;
}
cpu_relax();
- lock_page(eb->first_page);
+ mutex_lock(&eb->mutex);
return 0;
}
int btrfs_try_tree_lock(struct extent_buffer *eb)
{
- return TestSetPageLocked(eb->first_page);
+ return mutex_trylock(&eb->mutex);
}
int btrfs_tree_unlock(struct extent_buffer *eb)
{
- WARN_ON(!PageLocked(eb->first_page));
- unlock_page(eb->first_page);
+ mutex_unlock(&eb->mutex);
return 0;
}
int btrfs_tree_locked(struct extent_buffer *eb)
{
- return PageLocked(eb->first_page);
+ return mutex_is_locked(&eb->mutex);
}