[32/43] btrfs: hold a ref on the root in get_subvol_name_from_objectid

Commit Message

Josef Bacik Jan. 17, 2020, 9:25 p.m. UTC

We lookup the name of a subvol which means we'll cross into different
roots.  Hold a ref while we're doing the look ups in the fs_root we're
searching.

Signed-off-by: Josef Bacik <[e-mail]>
---
 fs/btrfs/super.c | 9 +++++++++
 1 file changed, 9 insertions(+)

Patch

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 3118bc01321e..5c3a1b7de6ee 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1101,6 +1101,10 @@  static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
 			ret = PTR_ERR(fs_root);
 			goto err;
 		}
+		if (!btrfs_grab_fs_root(fs_root)) {
+			ret = -ENOENT;
+			goto err;
+		}
 
 		/*
 		 * Walk up the filesystem tree by inode refs until we hit the
@@ -1113,13 +1117,16 @@  static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
 
 			ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
 			if (ret < 0) {
+				btrfs_put_fs_root(fs_root);
 				goto err;
 			} else if (ret > 0) {
 				ret = btrfs_previous_item(fs_root, path, dirid,
 							  BTRFS_INODE_REF_KEY);
 				if (ret < 0) {
+					btrfs_put_fs_root(fs_root);
 					goto err;
 				} else if (ret > 0) {
+					btrfs_put_fs_root(fs_root);
 					ret = -ENOENT;
 					goto err;
 				}
@@ -1136,6 +1143,7 @@  static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
 			ptr -= len + 1;
 			if (ptr < name) {
 				ret = -ENAMETOOLONG;
+				btrfs_put_fs_root(fs_root);
 				goto err;
 			}
 			read_extent_buffer(path->nodes[0], ptr + 1,
@@ -1143,6 +1151,7 @@  static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
 			ptr[0] = '/';
 			btrfs_release_path(path);
 		}
+		btrfs_put_fs_root(fs_root);
 	}
 
 	btrfs_free_path(path);