btrfs: add missing initialization in btrfs_check_shared

[sfrench/cifs-2.6.git] / fs / btrfs / backref.c

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 7d0dc100a09a816f3c1aec7089ebc7de98339114..26484648d0903298cbb68bff095232873e94673a 100644 (file)
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -216,7 +216,8 @@ static int prelim_ref_compare(struct prelim_ref *ref1,
        return 0;
 }
 
-void update_share_count(struct share_check *sc, int oldcount, int newcount)
+static void update_share_count(struct share_check *sc, int oldcount,
+                              int newcount)
 {
        if ((!sc) || (oldcount == 0 && newcount < 1))
                return;
@@ -1263,7 +1264,16 @@ again:
        while (node) {
                ref = rb_entry(node, struct prelim_ref, rbnode);
                node = rb_next(&ref->rbnode);
-               WARN_ON(ref->count < 0);
+               /*
+                * ref->count < 0 can happen here if there are delayed
+                * refs with a node->action of BTRFS_DROP_DELAYED_REF.
+                * prelim_ref_insert() relies on this when merging
+                * identical refs to keep the overall count correct.
+                * prelim_ref_insert() will merge only those refs
+                * which compare identically.  Any refs having
+                * e.g. different offsets would not be merged,
+                * and would retain their original ref->count < 0.
+                */
                if (roots && ref->count && ref->root_id && ref->parent == 0) {
                        if (sc && sc->root_objectid &&
                            ref->root_id != sc->root_objectid) {
@@ -1509,6 +1519,7 @@ int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
                if (!node)
                        break;
                bytenr = node->val;
+               shared.share_count = 0;
                cond_resched();
        }