btrfs-progs: check: lowmem: Fix false alert about orphan inode

Btrfs can delay inode deletion and in that case btrfs will unlink the
victim inode from its parent dir, and insert a marker to info btrfs to
delete it later.

In that case, such victim inode will have nlinks == 0, but is still
completely valid.
Original mode won't report such problem, but lowmem mode doesn't check
the ORPHAN_ITEM key for such inode, and can report false alert like:
------
ERROR: root 257 INODE[28891726] is orphan item
------

Fix such false alert by checking orphan item for inode whose nlink is 0.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Su Yue <suy.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/check/mode-lowmem.c b/check/mode-lowmem.c
index 6f1ea8d..077e61d 100644 (file)
--- a/check/mode-lowmem.c
+++ b/check/mode-lowmem.c
@@ -1861,6 +1861,24 @@ out:
        return ret;
 }
 
+static bool has_orphan_item(struct btrfs_root *root, u64 ino)
+{
+       struct btrfs_path path;
+       struct btrfs_key key;
+       int ret;
+
+       btrfs_init_path(&path);
+       key.objectid = BTRFS_ORPHAN_OBJECTID;
+       key.type = BTRFS_ORPHAN_ITEM_KEY;
+       key.offset = ino;
+
+       ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
+       btrfs_release_path(&path);
+       if (ret == 0)
+               return true;
+       return false;
+}
+
 /*
  * Check INODE_ITEM and related ITEMs (the same inode number)
  * 1. check link count
@@ -1890,6 +1908,7 @@ static int check_inode_item(struct btrfs_root *root, struct btrfs_path *path,
        u64 extent_size = 0;
        unsigned int dir;
        unsigned int nodatasum;
+       bool is_orphan = false;
        int slot;
        int ret;
        int err = 0;
@@ -2040,10 +2059,11 @@ out:
                                      root->objectid, inode_id, nlink, refs);
                        }
                } else if (!nlink) {
-                       if (repair)
+                       is_orphan = has_orphan_item(root, inode_id);
+                       if (!is_orphan && repair)
                                ret = repair_inode_orphan_item_lowmem(root,
                                                              path, inode_id);
-                       if (!repair || ret) {
+                       if (!is_orphan && (!repair || ret)) {
                                err |= ORPHAN_ITEM;
                                error("root %llu INODE[%llu] is orphan item",
                                      root->objectid, inode_id);