On Tue, 2020-04-28 at 21:13 +0800, Wu Bo wrote:
> 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.
>
The problem looks real, but...
> --
> 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;
Why did you make this case goto out_unlock instead of retrying as it did
before?
> + }
> +
> + 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:
--
Jeff Layton <jlayton@xxxxxxxxxx>
