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>

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 3bed6a7e4b22..aeaec84ebed8 100644
--- 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);