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authorJosef Bacik <jbacik@fusionio.com>2012-07-20 16:05:36 -0400
committerChris Mason <chris.mason@fusionio.com>2012-07-23 16:28:08 -0400
commite64860aa05048fa7a8483ca698b17c2caf5625cf (patch)
tree3bee3474a00fdbef80414a926c31187865392abe /fs/btrfs
parenta98cdb85b990765dbe80a215367ae007320bfeea (diff)
Btrfs: don't return true in releasepage unless we actually freed the eb
I noticed while looking at an extent_buffer race that we will unconditionally return 1 if we get down to release_extent_buffer after clearing the tree ref. However we can easily race in here and get a ref on the eb and not actually free the eb. So make release_extent_buffer return 1 if it free'd the eb and 0 if not so we can be a little kinder to the vm. Thanks, Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/extent_io.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index f08206fcfb22..e6243f787434 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4300,7 +4300,7 @@ static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head)
}
/* Expects to have eb->eb_lock already held */
-static void release_extent_buffer(struct extent_buffer *eb, gfp_t mask)
+static int release_extent_buffer(struct extent_buffer *eb, gfp_t mask)
{
WARN_ON(atomic_read(&eb->refs) == 0);
if (atomic_dec_and_test(&eb->refs)) {
@@ -4321,9 +4321,11 @@ static void release_extent_buffer(struct extent_buffer *eb, gfp_t mask)
btrfs_release_extent_buffer_page(eb, 0);
call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu);
- return;
+ return 1;
}
spin_unlock(&eb->refs_lock);
+
+ return 0;
}
void free_extent_buffer(struct extent_buffer *eb)
@@ -4962,7 +4964,6 @@ int try_release_extent_buffer(struct page *page, gfp_t mask)
spin_unlock(&eb->refs_lock);
return 0;
}
- release_extent_buffer(eb, mask);
- return 1;
+ return release_extent_buffer(eb, mask);
}