Btrfs: Fix infinite loop in btrfs_extent_post_op

btrfs_extent_post_op calls finish_current_insert and del_pending_extents. They
both may enter infinite loops.

finish_current_insert enters infinite loop if it only finds some backrefs to
update.  The fix is to check for pending backref updates before restarting the
loop.

The infinite loop in del_pending_extents is due to a the skipped variable
not being properly reset before looping around.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 3bed6a7e4b22ad5feeff67d7babf7beba6d59854..aeaec84ebed85b0cbe17d7cedd0edaf6a7860ee3 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2156,7 +2156,8 @@ again:
                ret = find_first_extent_bit(&info->extent_ins, search, &start,
                                            &end, EXTENT_WRITEBACK);
                if (ret) {
-                       if (skipped && all && !num_inserts) {
+                       if (skipped && all && !num_inserts &&
+                           list_empty(&update_list)) {
                                skipped = 0;
                                search = 0;
                                continue;
@@ -2544,6 +2545,7 @@ again:
                if (ret) {
                        if (all && skipped && !nr) {
                                search = 0;
+                               skipped = 0;
                                continue;
                        }
                        mutex_unlock(&info->extent_ins_mutex);