[PATCH v2 1/2] btrfs-progs: mkfs/rootdir: copy missing attributes for the rootdir inode

[Qu Wenruo <wqu@suse.com>]

[BUG]
When using "mkfs.btrfs" with "--rootdir" option, the top level inode
(rootdir) will not get the same xattr from the source dir:

  mkdir -p source_dir/
  touch source_dir/file
  setfattr -n user.rootdir_xattr source_dir/
  setfattr -n user.regular_xattr source_dir/file
  mkfs.btrfs -f --rootdir source_dir $dev
  mount $dev $mnt
  getfattr $mnt
  # Nothing <<<
  getfattr $mnt/file
  # file: $mnt/file
  user.regular_xattr <<<

[CAUSE]
In function traverse_directory(), we only call add_xattr_item() for all
the child inodes, not really for the rootdir inode itself, leading to
the missing xattr items.

Not only xattr, in fact we also miss the uid/gid/timestamps/mode for the
rootdir inode.

[FIX]
Extract a dedicated function, copy_rootdir_inode(), to handle every
needed attributes for the rootdir inode, including:

- xattr
- uid
- gid
- mode
- timestamps

Issue: #688
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 mkfs/rootdir.c | 88 ++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 67 insertions(+), 21 deletions(-)

diff --git a/mkfs/rootdir.c b/mkfs/rootdir.c
index a413a31eb2d6..fde5efdebe8b 100644
--- a/mkfs/rootdir.c
+++ b/mkfs/rootdir.c
@@ -429,6 +429,69 @@ end:
 	return ret;
 }
 
+static int copy_rootdir_inode(struct btrfs_trans_handle *trans,
+			      struct btrfs_root *root, const char *dir_name)
+{
+	u64 root_dir_inode_size;
+	struct btrfs_inode_item *inode_item;
+	struct btrfs_path path = { 0 };
+	struct btrfs_key key;
+	struct extent_buffer *leaf;
+	struct stat st;
+	int ret;
+
+	ret = lstat(dir_name, &st);
+	if (ret < 0) {
+		ret = -errno;
+		error("lstat failed for direcotry %s: $m", dir_name);
+		return ret;
+	}
+
+	ret = add_xattr_item(trans, root, btrfs_root_dirid(&root->root_item),
+			     dir_name);
+	if (ret < 0) {
+		errno = -ret;
+		error("failed to add xattr item for the top level inode: %m");
+		return ret;
+	}
+
+	key.objectid = btrfs_root_dirid(&root->root_item);
+	key.offset = 0;
+	key.type = BTRFS_INODE_ITEM_KEY;
+	ret = btrfs_lookup_inode(trans, root, &path, &key, 1);
+	if (ret > 0)
+		ret = -ENOENT;
+	if (ret) {
+		error("failed to lookup root dir: %d", ret);
+		goto error;
+	}
+
+	leaf = path.nodes[0];
+	inode_item = btrfs_item_ptr(leaf, path.slots[0],
+				    struct btrfs_inode_item);
+
+	root_dir_inode_size = calculate_dir_inode_size(dir_name);
+	btrfs_set_inode_size(leaf, inode_item, root_dir_inode_size);
+
+	/* Unlike fill_inode_item, we only need to copy part of the attributes. */
+	btrfs_set_inode_uid(leaf, inode_item, st.st_uid);
+	btrfs_set_inode_gid(leaf, inode_item, st.st_gid);
+	btrfs_set_inode_mode(leaf, inode_item, st.st_mode);
+	btrfs_set_timespec_sec(leaf, &inode_item->atime, st.st_atime);
+	btrfs_set_timespec_nsec(leaf, &inode_item->atime, 0);
+	btrfs_set_timespec_sec(leaf, &inode_item->ctime, st.st_ctime);
+	btrfs_set_timespec_nsec(leaf, &inode_item->ctime, 0);
+	btrfs_set_timespec_sec(leaf, &inode_item->mtime, st.st_mtime);
+	btrfs_set_timespec_nsec(leaf, &inode_item->mtime, 0);
+	btrfs_set_timespec_sec(leaf, &inode_item->otime, 0);
+	btrfs_set_timespec_nsec(leaf, &inode_item->otime, 0);
+	btrfs_mark_buffer_dirty(leaf);
+
+error:
+	btrfs_release_path(&path);
+	return ret;
+}
+
 static int traverse_directory(struct btrfs_trans_handle *trans,
 			      struct btrfs_root *root, const char *dir_name,
 			      struct directory_name_entry *dir_head)
@@ -436,7 +499,6 @@ static int traverse_directory(struct btrfs_trans_handle *trans,
 	int ret = 0;
 
 	struct btrfs_inode_item cur_inode;
-	struct btrfs_inode_item *inode_item;
 	int count, i, dir_index_cnt;
 	struct dirent **files;
 	struct stat st;
@@ -445,10 +507,6 @@ static int traverse_directory(struct btrfs_trans_handle *trans,
 	ino_t parent_inum, cur_inum;
 	ino_t highest_inum = 0;
 	const char *parent_dir_name;
-	struct btrfs_path path = { 0 };
-	struct extent_buffer *leaf;
-	struct btrfs_key root_dir_key;
-	u64 root_dir_inode_size = 0;
 
 	/* Add list for source directory */
 	dir_entry = malloc(sizeof(struct directory_name_entry));
@@ -466,25 +524,13 @@ static int traverse_directory(struct btrfs_trans_handle *trans,
 	dir_entry->inum = parent_inum;
 	list_add_tail(&dir_entry->list, &dir_head->list);
 
-	root_dir_key.objectid = btrfs_root_dirid(&root->root_item);
-	root_dir_key.offset = 0;
-	root_dir_key.type = BTRFS_INODE_ITEM_KEY;
-	ret = btrfs_lookup_inode(trans, root, &path, &root_dir_key, 1);
-	if (ret) {
-		error("failed to lookup root dir: %d", ret);
+	ret = copy_rootdir_inode(trans, root, dir_name);
+	if (ret < 0) {
+		errno = -ret;
+		error("failed to copy rootdir inode: %m");
 		goto fail_no_dir;
 	}
 
-	leaf = path.nodes[0];
-	inode_item = btrfs_item_ptr(leaf, path.slots[0],
-				    struct btrfs_inode_item);
-
-	root_dir_inode_size = calculate_dir_inode_size(dir_name);
-	btrfs_set_inode_size(leaf, inode_item, root_dir_inode_size);
-	btrfs_mark_buffer_dirty(leaf);
-
-	btrfs_release_path(&path);
-
 	do {
 		parent_dir_entry = list_entry(dir_head->list.next,
 					      struct directory_name_entry,
-- 
2.42.0