btrfs: use list_last_entry in add_falloc_range

Instead of calling list_entry with head->prev simply call
list_last_entry which makes it obvious which member of the list is
being referred. This allows to remove the extra 'prev' pointer.

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/file.c b/fs/btrfs/file.c
index 55f68422061d1aac01d38a5c459f69c5d13d1fc6..a56a13999bd66e9be3f1649045585e785efb606a 100644 (file)
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3034,7 +3034,6 @@ struct falloc_range {
  */
 static int add_falloc_range(struct list_head *head, u64 start, u64 len)
 {
-       struct falloc_range *prev = NULL;
        struct falloc_range *range = NULL;
 
        if (list_empty(head))
@@ -3044,9 +3043,9 @@ static int add_falloc_range(struct list_head *head, u64 start, u64 len)
         * As fallocate iterate by bytenr order, we only need to check
         * the last range.
         */
-       prev = list_entry(head->prev, struct falloc_range, list);
-       if (prev->start + prev->len == start) {
-               prev->len += len;
+       range = list_last_entry(head, struct falloc_range, list);
+       if (range->start + range->len == start) {
+               range->len += len;
                return 0;
        }
 insert: