Btrfs: restructure try_release_extent_buffer()

restructure try_release_extent_buffer() and write a function to release the
extent buffer. It will be used later.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d74e6af..6e3b326 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3104,6 +3104,39 @@ static void __free_extent_buffer(struct extent_buffer *eb)
        kmem_cache_free(extent_buffer_cache, eb);
 }
 
+/*
+ * Helper for releasing extent buffer page.
+ */
+static void btrfs_release_extent_buffer_page(struct extent_buffer *eb,
+                                               unsigned long start_idx)
+{
+       unsigned long index;
+       struct page *page;
+
+       if (!eb->first_page)
+               return;
+
+       index = num_extent_pages(eb->start, eb->len);
+       if (start_idx >= index)
+               return;
+
+       do {
+               index--;
+               page = extent_buffer_page(eb, index);
+               if (page)
+                       page_cache_release(page);
+       } while (index != start_idx);
+}
+
+/*
+ * Helper for releasing the extent buffer.
+ */
+static inline void btrfs_release_extent_buffer(struct extent_buffer *eb)
+{
+       btrfs_release_extent_buffer_page(eb, 0);
+       __free_extent_buffer(eb);
+}
+
 struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
                                          u64 start, unsigned long len,
                                          struct page *page0,
@@ -3181,10 +3214,7 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
 free_eb:
        if (!atomic_dec_and_test(&eb->refs))
                return exists;
-       for (index = 1; index < i; index++)
-               page_cache_release(extent_buffer_page(eb, index));
-       page_cache_release(extent_buffer_page(eb, 0));
-       __free_extent_buffer(eb);
+       btrfs_release_extent_buffer(eb);
        return exists;
 }
 
@@ -3838,8 +3868,6 @@ int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page)
        u64 start = page_offset(page);
        struct extent_buffer *eb;
        int ret = 1;
-       unsigned long i;
-       unsigned long num_pages;
 
        spin_lock(&tree->buffer_lock);
        eb = buffer_search(tree, start);
@@ -3854,12 +3882,10 @@ int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page)
                ret = 0;
                goto out;
        }
-       /* at this point we can safely release the extent buffer */
-       num_pages = num_extent_pages(eb->start, eb->len);
-       for (i = 0; i < num_pages; i++)
-               page_cache_release(extent_buffer_page(eb, i));
+
        rb_erase(&eb->rb_node, &tree->buffer);
-       __free_extent_buffer(eb);
+       /* at this point we can safely release the extent buffer */
+       btrfs_release_extent_buffer(eb);
 out:
        spin_unlock(&tree->buffer_lock);
        return ret;