[PATCH 4.9 155/329] ceph: fix dentry leak when failing to init debugfs

From: Greg Kroah-Hartman
Date: Mon May 28 2018 - 06:34:48 EST


4.9-stable review patch. If anyone has any objections, please let me know.

------------------

From: Chengguang Xu <cgxu519@xxxxxxxxxx>

[ Upstream commit 18106734b512664a8541026519ce4b862498b6c3 ]

When failing from ceph_fs_debugfs_init() in ceph_real_mount(),
there is lack of dput of root_dentry and it causes slab errors,
so change the calling order of ceph_fs_debugfs_init() and
open_root_dentry() and do some cleanups to avoid this issue.

Signed-off-by: Chengguang Xu <cgxu519@xxxxxxxxxx>
Reviewed-by: "Yan, Zheng" <zyan@xxxxxxxxxx>
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ceph/super.c | 16 +++++-----------
1 file changed, 5 insertions(+), 11 deletions(-)

--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -816,7 +816,6 @@ static struct dentry *ceph_real_mount(st
int err;
unsigned long started = jiffies; /* note the start time */
struct dentry *root;
- int first = 0; /* first vfsmount for this super_block */

dout("mount start %p\n", fsc);
mutex_lock(&fsc->client->mount_mutex);
@@ -834,17 +833,17 @@ static struct dentry *ceph_real_mount(st
path = fsc->mount_options->server_path + 1;
dout("mount opening path %s\n", path);
}
+
+ err = ceph_fs_debugfs_init(fsc);
+ if (err < 0)
+ goto out;
+
root = open_root_dentry(fsc, path, started);
if (IS_ERR(root)) {
err = PTR_ERR(root);
goto out;
}
fsc->sb->s_root = dget(root);
- first = 1;
-
- err = ceph_fs_debugfs_init(fsc);
- if (err < 0)
- goto fail;
} else {
root = dget(fsc->sb->s_root);
}
@@ -854,11 +853,6 @@ static struct dentry *ceph_real_mount(st
mutex_unlock(&fsc->client->mount_mutex);
return root;

-fail:
- if (first) {
- dput(fsc->sb->s_root);
- fsc->sb->s_root = NULL;
- }
out:
mutex_unlock(&fsc->client->mount_mutex);
return ERR_PTR(err);