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Commit e64860aa authored by Josef Bacik's avatar Josef Bacik Committed by Chris Mason
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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: default avatarJosef Bacik <jbacik@fusionio.com>
parent a98cdb85

fs/btrfs/extent_io.c

+5 −4
Original line number Diff line number Diff line
@@ -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);

}