[PATCH V2] fs/ceph:fix double unlock in handle_cap_export()

From: Wu Bo
Date: Tue Apr 28 2020 - 09:14:53 EST


if the ceph_mdsc_open_export_target_session() return fails,
should add a lock to avoid twice unlocking.
Because the lock will be released at the retry or out_unlock tag.

--
v1 -> v2:
add spin_lock(&ci->i_ceph_lock) before goto out_unlock tag.

Signed-off-by: Wu Bo <wubo40@xxxxxxxxxx>
---
fs/ceph/caps.c | 27 +++++++++++++++------------
1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 185db76..414c0e2 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -3731,22 +3731,25 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,

/* open target session */
tsession = ceph_mdsc_open_export_target_session(mdsc, target);
- if (!IS_ERR(tsession)) {
- if (mds > target) {
- mutex_lock(&session->s_mutex);
- mutex_lock_nested(&tsession->s_mutex,
- SINGLE_DEPTH_NESTING);
- } else {
- mutex_lock(&tsession->s_mutex);
- mutex_lock_nested(&session->s_mutex,
- SINGLE_DEPTH_NESTING);
- }
- new_cap = ceph_get_cap(mdsc, NULL);
- } else {
+ if (IS_ERR(tsession)) {
WARN_ON(1);
tsession = NULL;
target = -1;
+ mutex_lock(&session->s_mutex);
+ spin_lock(&ci->i_ceph_lock);
+ goto out_unlock;
+ }
+
+ if (mds > target) {
+ mutex_lock(&session->s_mutex);
+ mutex_lock_nested(&tsession->s_mutex,
+ SINGLE_DEPTH_NESTING);
+ } else {
+ mutex_lock(&tsession->s_mutex);
+ mutex_lock_nested(&session->s_mutex,
+ SINGLE_DEPTH_NESTING);
}
+ new_cap = ceph_get_cap(mdsc, NULL);
goto retry;

out_unlock:
--
1.8.3.1