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| author | Josef Bacik <jbacik@fusionio.com> | 2012-07-20 16:05:36 -0400 |
|---|---|---|
| committer | Chris Mason <chris.mason@fusionio.com> | 2012-07-23 16:28:08 -0400 |
| commit | e64860aa05048fa7a8483ca698b17c2caf5625cf (patch) | |
| tree | 3bee3474a00fdbef80414a926c31187865392abe | |
| parent | a98cdb85b990765dbe80a215367ae007320bfeea (diff) | |
| download | linux-3.10-e64860aa05048fa7a8483ca698b17c2caf5625cf.tar.gz linux-3.10-e64860aa05048fa7a8483ca698b17c2caf5625cf.tar.bz2 linux-3.10-e64860aa05048fa7a8483ca698b17c2caf5625cf.zip | |
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>
| -rw-r--r-- | fs/btrfs/extent_io.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index f08206fcfb2..e6243f78743 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); } |