Btrfs: fix a bug in parsing return value in logical resolve

In logical resolve, we parse extent_from_logical()'s 'ret' as a kind of flag.

It is possible to lose our errors because
(-EXXXX & BTRFS_EXTENT_FLAG_TREE_BLOCK) is true.

I'm not sure if it is on purpose, it just looks too hacky if it is.
I'd rather use a real flag and a 'ret' to catch errors.

Acked-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Liu Bo <liub.liubo@gmail.com>

1 files changed, 16 insertions, 8 deletions

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index e600857d3ca4..ab286e5bfe33 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -1193,7 +1193,8 @@ char *btrfs_iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
  * tree blocks and <0 on error.
  */
 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
-                        struct btrfs_path *path, struct btrfs_key *found_key)
+                        struct btrfs_path *path, struct btrfs_key *found_key,
+                        u64 *flags_ret)
 {
         int ret;
         u64 flags;
@@ -1237,10 +1238,17 @@ int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
                  (unsigned long long)found_key->objectid,
                  (unsigned long long)found_key->offset,
                  (unsigned long long)flags, item_size);
-        if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
-                return BTRFS_EXTENT_FLAG_TREE_BLOCK;
-        if (flags & BTRFS_EXTENT_FLAG_DATA)
-                return BTRFS_EXTENT_FLAG_DATA;
+
+        WARN_ON(!flags_ret);
+        if (flags_ret) {
+                if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
+                        *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
+                else if (flags & BTRFS_EXTENT_FLAG_DATA)
+                        *flags_ret = BTRFS_EXTENT_FLAG_DATA;
+                else
+                        BUG_ON(1);
+                return 0;
+        }
 
         return -EIO;
 }
@@ -1433,15 +1441,15 @@ int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
 {
         int ret;
         u64 extent_item_pos;
+        u64 flags = 0;
         struct btrfs_key found_key;
         int search_commit_root = path->search_commit_root;
 
-        ret = extent_from_logical(fs_info, logical, path,
-                                        &found_key);
+        ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
         btrfs_release_path(path);
         if (ret < 0)
                 return ret;
-        if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK)
+        if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
                 return -EINVAL;
 
         extent_item_pos = logical - found_key.objectid;