btrfs-progs: dir-item: Don't do extra filetype validation check for btrfs_match_dir_item_name

verify_dir_item() is called in btrfs_match_dir_item_name() to ensure we
won't search beyond item boundary and does extra filetype check.

However in the following call chain, such extra filetype check can cause
problems:

1) btrfs_add_link()
   |- check_dir_conflict()
      |- btrfs_lookup_dir_index()
         |- btrfs_match_dir_item_name()

   And if we have an offending dir index whose filetype is invalid,
   btrfs_match_dir_item_name() will return NULL, meaning no match dir
   index is found.
   So btrfs_add_link() will still try to insert a dir index, which may
   have same key->offset and leading to duplicated dir index.

2) btrfs_unlink()
   |- btrfs_lookup_dir_index()
      |- btrfs_lookup_dir_index()
         |- btrfs_match_dir_item_name()

   For the same offending dir index with invalid filetype, this will
   return NULL, and btrfs_unlink() will just consider there is no
   existing dir_index and do nothing.
   Leave an orphan and invalid dir_index hanging there forever.

The patch removes the extra filetype check, as "btrfs check" can already
handle invalid filetype correctly for both modes.

And this makes "btrfs check --repair --mode=lowmem" to delete the
offending dir index to repair it correctly.

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

dir-item.c

@@ -294,12 +294,6 @@ static int verify_dir_item(struct btrfs_root *root,
 	u16 namelen = BTRFS_NAME_LEN;
 	u8 type = btrfs_dir_type(leaf, dir_item);
 
-	if (type >= BTRFS_FT_MAX) {
-		fprintf(stderr, "invalid dir item type: %d\n",
-		       (int)type);
-		return 1;
-	}
-
 	if (type == BTRFS_FT_XATTR)
 		namelen = XATTR_NAME_MAX;