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>
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a98cdb85b9
Коммит
e64860aa05
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@ -4300,7 +4300,7 @@ static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head)
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}
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/* Expects to have eb->eb_lock already held */
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static void release_extent_buffer(struct extent_buffer *eb, gfp_t mask)
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static int release_extent_buffer(struct extent_buffer *eb, gfp_t mask)
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{
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WARN_ON(atomic_read(&eb->refs) == 0);
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if (atomic_dec_and_test(&eb->refs)) {
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@ -4321,9 +4321,11 @@ static void release_extent_buffer(struct extent_buffer *eb, gfp_t mask)
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btrfs_release_extent_buffer_page(eb, 0);
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call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu);
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return;
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return 1;
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}
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spin_unlock(&eb->refs_lock);
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return 0;
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}
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void free_extent_buffer(struct extent_buffer *eb)
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@ -4962,7 +4964,6 @@ int try_release_extent_buffer(struct page *page, gfp_t mask)
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spin_unlock(&eb->refs_lock);
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return 0;
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}
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release_extent_buffer(eb, mask);
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return 1;
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return release_extent_buffer(eb, mask);
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}
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