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Btrfs: Use a mutex in the extent buffer for tree block locking

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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>
This commit is contained in:
Chris Mason
2008-07-22 11:18:08 -04:00
parent 6af118ce51
commit a61e6f29dc
4 changed files with 17 additions and 13 deletions
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13
fs/btrfs/locking.c
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@@ -29,32 +29,31 @@ int btrfs_tree_lock(struct extent_buffer *eb)
{
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);
}