[PATCH V3] fs/ceph:fix double unlock in handle_cap_export()

[PATCH V3] fs/ceph:fix double unlock in handle_cap_export()

[Wu Bo]

If the ceph_mdsc_open_export_target_session() return fails,
we should add mutex_lock(&session->s_mutex) on IS_ERR(tsession) block 
to avoid twice unlocking. because the session->s_mutex will be unlock
at the out_unlock lable.

--
v2 -> v3:
  - Rewrite solution, adding a mutex_lock(&session->s_mutex) 
    to the IS_ERR(tsession) block.
  - Modify the comment more clearly.
v1 -> v2:
  - add spin_lock(&ci->i_ceph_lock) before goto out_unlock lable
     

Signed-off-by: Wu Bo <wubo40@huawei.com>
---
 fs/ceph/caps.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 185db76..d27d778 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -3746,6 +3746,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
 		WARN_ON(1);
 		tsession = NULL;
 		target = -1;
+		mutex_lock(&session->s_mutex);
 	}
 	goto retry;
 
-- 
1.8.3.1

Re: [PATCH V3] fs/ceph:fix double unlock in handle_cap_export()

[Yan, Zheng]

On Thu, Apr 30, 2020 at 2:13 PM Wu Bo <wubo40@huawei.com> wrote:
>
> If the ceph_mdsc_open_export_target_session() return fails,
> we should add mutex_lock(&session->s_mutex) on IS_ERR(tsession) block
> to avoid twice unlocking. because the session->s_mutex will be unlock
> at the out_unlock lable.
>
> --
> v2 -> v3:
>   - Rewrite solution, adding a mutex_lock(&session->s_mutex)
>     to the IS_ERR(tsession) block.
>   - Modify the comment more clearly.
> v1 -> v2:
>   - add spin_lock(&ci->i_ceph_lock) before goto out_unlock lable
>
>
> Signed-off-by: Wu Bo <wubo40@huawei.com>
> ---
>  fs/ceph/caps.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index 185db76..d27d778 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -3746,6 +3746,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
>                 WARN_ON(1);
>                 tsession = NULL;
>                 target = -1;
> +               mutex_lock(&session->s_mutex);
>         }
>         goto retry;
>
> --
> 1.8.3.1
>

 Reviewed-by: "Yan, Zheng" <zyan@redhat.com>

Re: [PATCH V3] fs/ceph:fix double unlock in handle_cap_export()

[Jeff Layton]

On Thu, 2020-04-30 at 14:12 +0800, Wu Bo wrote:
> If the ceph_mdsc_open_export_target_session() return fails,
> we should add mutex_lock(&session->s_mutex) on IS_ERR(tsession) block 
> to avoid twice unlocking. because the session->s_mutex will be unlock
> at the out_unlock lable.
> 
> --
> v2 -> v3:
>   - Rewrite solution, adding a mutex_lock(&session->s_mutex) 
>     to the IS_ERR(tsession) block.
>   - Modify the comment more clearly.
> v1 -> v2:
>   - add spin_lock(&ci->i_ceph_lock) before goto out_unlock lable
> 

For future reference, notes like this should go a little lower...

>      
> 
> Signed-off-by: Wu Bo <wubo40@huawei.com>
> ---
>  fs/ceph/caps.c | 1 +
>  1 file changed, 1 insertion(+)
> 

If you put the patch version notes here, they'll be stripped out when we
go to merge the patch with git-am.

> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index 185db76..d27d778 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -3746,6 +3746,7 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
>  		WARN_ON(1);
>  		tsession = NULL;
>  		target = -1;
> +		mutex_lock(&session->s_mutex);
>  	}
>  	goto retry;
>  

Looks good. Merged, but I did clean up the verbiage in the changelog a
bit.

Thanks!
-- 
Jeff Layton <jlayton@kernel.org>