Btrfs: Fix failure cleanups when allocating extent buffers fail

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index b0677c8..c976615 100644 (file)
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -2106,25 +2106,17 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_map_tree *tree,
 
        spin_lock(&tree->lru_lock);
        eb = find_lru(tree, start, len);
-       if (eb) {
-               goto lru_add;
-       }
        spin_unlock(&tree->lru_lock);
-
        if (eb) {
-               memset(eb, 0, sizeof(*eb));
-       } else {
-               eb = kmem_cache_zalloc(extent_buffer_cache, mask);
+               return eb;
        }
+
+       eb = kmem_cache_zalloc(extent_buffer_cache, mask);
        INIT_LIST_HEAD(&eb->lru);
        eb->start = start;
        eb->len = len;
        atomic_set(&eb->refs, 1);
 
-       spin_lock(&tree->lru_lock);
-lru_add:
-       add_lru(tree, eb);
-       spin_unlock(&tree->lru_lock);
        return eb;
 }
 
@@ -2151,7 +2143,7 @@ struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
                return NULL;
 
        if (eb->flags & EXTENT_BUFFER_FILLED)
-               return eb;
+               goto lru_add;
 
        if (page0) {
                eb->first_page = page0;
@@ -2169,11 +2161,6 @@ struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
                p = find_or_create_page(mapping, index, mask | __GFP_HIGHMEM);
                if (!p) {
                        WARN_ON(1);
-                       /* make sure the free only frees the pages we've
-                        * grabbed a reference on
-                        */
-                       eb->len = i << PAGE_CACHE_SHIFT;
-                       eb->start &= ~((u64)PAGE_CACHE_SIZE - 1);
                        goto fail;
                }
                set_page_extent_mapped(p);
@@ -2192,9 +2179,20 @@ struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
        if (uptodate)
                eb->flags |= EXTENT_UPTODATE;
        eb->flags |= EXTENT_BUFFER_FILLED;
+
+lru_add:
+       spin_lock(&tree->lru_lock);
+       add_lru(tree, eb);
+       spin_unlock(&tree->lru_lock);
        return eb;
+
 fail:
-       free_extent_buffer(eb);
+       if (!atomic_dec_and_test(&eb->refs))
+               return NULL;
+       for (index = 0; index < i; index++) {
+               page_cache_release(extent_buffer_page(eb, index));
+       }
+       __free_extent_buffer(eb);
        return NULL;
 }
 EXPORT_SYMBOL(alloc_extent_buffer);
@@ -2204,7 +2202,8 @@ struct extent_buffer *find_extent_buffer(struct extent_map_tree *tree,
                                          gfp_t mask)
 {
        unsigned long num_pages = num_extent_pages(start, len);
-       unsigned long i; unsigned long index = start >> PAGE_CACHE_SHIFT;
+       unsigned long i;
+       unsigned long index = start >> PAGE_CACHE_SHIFT;
        struct extent_buffer *eb;
        struct page *p;
        struct address_space *mapping = tree->mapping;
@@ -2215,16 +2214,11 @@ struct extent_buffer *find_extent_buffer(struct extent_map_tree *tree,
                return NULL;
 
        if (eb->flags & EXTENT_BUFFER_FILLED)
-               return eb;
+               goto lru_add;
 
        for (i = 0; i < num_pages; i++, index++) {
                p = find_lock_page(mapping, index);
                if (!p) {
-                       /* make sure the free only frees the pages we've
-                        * grabbed a reference on
-                        */
-                       eb->len = i << PAGE_CACHE_SHIFT;
-                       eb->start &= ~((u64)PAGE_CACHE_SIZE - 1);
                        goto fail;
                }
                set_page_extent_mapped(p);
@@ -2245,9 +2239,19 @@ struct extent_buffer *find_extent_buffer(struct extent_map_tree *tree,
        if (uptodate)
                eb->flags |= EXTENT_UPTODATE;
        eb->flags |= EXTENT_BUFFER_FILLED;
+
+lru_add:
+       spin_lock(&tree->lru_lock);
+       add_lru(tree, eb);
+       spin_unlock(&tree->lru_lock);
        return eb;
 fail:
-       free_extent_buffer(eb);
+       if (!atomic_dec_and_test(&eb->refs))
+               return NULL;
+       for (index = 0; index < i; index++) {
+               page_cache_release(extent_buffer_page(eb, index));
+       }
+       __free_extent_buffer(eb);
        return NULL;
 }
 EXPORT_SYMBOL(find_extent_buffer);