btrfs: Refactor loop in btrfs_release_extent_buffer_page

The purpose of the function is to free all the pages comprising an
extent buffer. This can be achieved with a simple for loop rather than
the slightly more involved 'do {} while' construct. So rewrite the
loop using a 'for' construct. Additionally we can never have an
extent_buffer that has 0 pages so remove the check for index == 0. No
functional changes.

The reversed order used to have a meaning in the past where the first
page served as a blocking point for several callers. See eg
4f2de97acee6532b36dd6e99 ("Btrfs: set page->private to the eb").

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 96039dd56c72e01061ae08e8e60b7fe3d14ffce8..66b5272bbaab331eec9492785f8b369a1f3de0ae 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4647,19 +4647,16 @@ int extent_buffer_under_io(struct extent_buffer *eb)
  */
 static void btrfs_release_extent_buffer_page(struct extent_buffer *eb)
 {
-       int index;
-       struct page *page;
+       int i;
+       int num_pages;
        int mapped = !test_bit(EXTENT_BUFFER_DUMMY, &eb->bflags);
 
        BUG_ON(extent_buffer_under_io(eb));
 
-       index = num_extent_pages(eb);
-       if (index == 0)
-               return;
+       num_pages = num_extent_pages(eb);
+       for (i = 0; i < num_pages; i++) {
+               struct page *page = eb->pages[i];
 
-       do {
-               index--;
-               page = eb->pages[index];
                if (!page)
                        continue;
                if (mapped)
@@ -4691,7 +4688,7 @@ static void btrfs_release_extent_buffer_page(struct extent_buffer *eb)
 
                /* One for when we allocated the page */
                put_page(page);
-       } while (index != 0);
+       }
 }
 
 /*