Re: [PATCH 2/5] ceph: export iterate_sessions

[Jeff Layton <jlayton@kernel.org>]

On Tue, 2021-06-29 at 12:42 +0800, xiubli@redhat.com wrote:
> From: Xiubo Li <xiubli@redhat.com>
> 
> Signed-off-by: Xiubo Li <xiubli@redhat.com>
> ---
>  fs/ceph/caps.c       | 26 +-----------------------
>  fs/ceph/mds_client.c | 47 +++++++++++++++++++++++++++++---------------
>  fs/ceph/mds_client.h |  3 +++
>  3 files changed, 35 insertions(+), 41 deletions(-)
> 
> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index e712826ea3f1..c6a3352a4d52 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -4280,33 +4280,9 @@ static void flush_dirty_session_caps(struct ceph_mds_session *s)
>  	dout("flush_dirty_caps done\n");
>  }
>  
> -static void iterate_sessions(struct ceph_mds_client *mdsc,
> -			     void (*cb)(struct ceph_mds_session *))
> -{
> -	int mds;
> -
> -	mutex_lock(&mdsc->mutex);
> -	for (mds = 0; mds < mdsc->max_sessions; ++mds) {
> -		struct ceph_mds_session *s;
> -
> -		if (!mdsc->sessions[mds])
> -			continue;
> -
> -		s = ceph_get_mds_session(mdsc->sessions[mds]);
> -		if (!s)
> -			continue;
> -
> -		mutex_unlock(&mdsc->mutex);
> -		cb(s);
> -		ceph_put_mds_session(s);
> -		mutex_lock(&mdsc->mutex);
> -	}
> -	mutex_unlock(&mdsc->mutex);
> -}
> -
>  void ceph_flush_dirty_caps(struct ceph_mds_client *mdsc)
>  {
> -	iterate_sessions(mdsc, flush_dirty_session_caps);
> +	ceph_mdsc_iterate_sessions(mdsc, flush_dirty_session_caps, true);
>  }
>  
>  void __ceph_touch_fmode(struct ceph_inode_info *ci,
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index e49d3e230712..96bef289f58f 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -802,6 +802,33 @@ static void put_request_session(struct ceph_mds_request *req)
>  	}
>  }
>  
> +void ceph_mdsc_iterate_sessions(struct ceph_mds_client *mdsc,
> +			       void (*cb)(struct ceph_mds_session *),
> +			       bool check_state)
> +{
> +	int mds;
> +
> +	mutex_lock(&mdsc->mutex);
> +	for (mds = 0; mds < mdsc->max_sessions; ++mds) {
> +		struct ceph_mds_session *s;
> +
> +		s = __ceph_lookup_mds_session(mdsc, mds);
> +		if (!s)
> +			continue;
> +
> +		if (check_state && !check_session_state(s)) {
> +			ceph_put_mds_session(s);
> +			continue;
> +		}
> +
> +		mutex_unlock(&mdsc->mutex);
> +		cb(s);
> +		ceph_put_mds_session(s);
> +		mutex_lock(&mdsc->mutex);
> +	}
> +	mutex_unlock(&mdsc->mutex);
> +}
> +
>  void ceph_mdsc_release_request(struct kref *kref)
>  {
>  	struct ceph_mds_request *req = container_of(kref,
> @@ -4416,22 +4443,10 @@ void ceph_mdsc_lease_send_msg(struct ceph_mds_session *session,
>  /*
>   * lock unlock sessions, to wait ongoing session activities
>   */
> -static void lock_unlock_sessions(struct ceph_mds_client *mdsc)
> +static void lock_unlock_session(struct ceph_mds_session *s)
>  {
> -	int i;
> -
> -	mutex_lock(&mdsc->mutex);
> -	for (i = 0; i < mdsc->max_sessions; i++) {
> -		struct ceph_mds_session *s = __ceph_lookup_mds_session(mdsc, i);
> -		if (!s)
> -			continue;
> -		mutex_unlock(&mdsc->mutex);
> -		mutex_lock(&s->s_mutex);
> -		mutex_unlock(&s->s_mutex);
> -		ceph_put_mds_session(s);
> -		mutex_lock(&mdsc->mutex);
> -	}
> -	mutex_unlock(&mdsc->mutex);
> +	mutex_lock(&s->s_mutex);
> +	mutex_unlock(&s->s_mutex);
>  }
>  

Your patch doesn't materially change this, but it sure would be nice to
know what purpose this lock/unlock garbage serves. Barf.

>  static void maybe_recover_session(struct ceph_mds_client *mdsc)
> @@ -4683,7 +4698,7 @@ void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc)
>  	dout("pre_umount\n");
>  	mdsc->stopping = 1;
>  
> -	lock_unlock_sessions(mdsc);
> +	ceph_mdsc_iterate_sessions(mdsc, lock_unlock_session, false);
>  	ceph_flush_dirty_caps(mdsc);
>  	wait_requests(mdsc);
>  
> diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
> index bf2683f0ba43..fca2cf427eaf 100644
> --- a/fs/ceph/mds_client.h
> +++ b/fs/ceph/mds_client.h
> @@ -523,6 +523,9 @@ static inline void ceph_mdsc_put_request(struct ceph_mds_request *req)
>  	kref_put(&req->r_kref, ceph_mdsc_release_request);
>  }
>  
> +extern void ceph_mdsc_iterate_sessions(struct ceph_mds_client *mdsc,
> +				       void (*cb)(struct ceph_mds_session *),
> +				       bool check_state);
>  extern struct ceph_msg *ceph_create_session_msg(u32 op, u64 seq);
>  extern void __ceph_queue_cap_release(struct ceph_mds_session *session,
>  				    struct ceph_cap *cap);

Again, not really exporting this function, so maybe reword the subject
line?

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