[PATCH 34/44] btrfs: hold a ref on the root in get_subvol_name_from_objectid

Josef Bacik
2019-12-06T14:46:43Z

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 <josef@toxicpanda.com>
---
fs/btrfs/super.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index e387ca1ac0e5..9c50bee71de9 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1082,6 +1082,10 @@ 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
@@ -1094,13 +1098,16 @@ 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;
}
@@ -1117,6 +1124,7 @@ 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,
@@ -1124,6 +1132,7 @@ 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);
--
2.23.0