> On 19 Oct 2017, at 20:53, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
>
> From: Jeff Layton <jlayton@xxxxxxxxxx>
>
> Functions that release a lock taken in a parent frame are notoriously
> hard to follow. Split cleanup_cap_releases into two functions, one to
> detach the cap releases from the session (which should be called with
> the spinlock held), and another to dispose of those caps.
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> fs/ceph/mds_client.c | 34 +++++++++++++++++++++-------------
> 1 file changed, 21 insertions(+), 13 deletions(-)
>
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index f23c820daaed..d58cb17ed491 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -1038,22 +1038,23 @@ void ceph_mdsc_open_export_target_sessions(struct ceph_mds_client *mdsc,
> * session caps
> */
>
> -/* caller holds s_cap_lock, we drop it */
> -static void cleanup_cap_releases(struct ceph_mds_client *mdsc,
> - struct ceph_mds_session *session)
> - __releases(session->s_cap_lock)
> +static void detach_cap_releases(struct ceph_mds_session *session,
> + struct list_head *target)
> {
> - LIST_HEAD(tmp_list);
> - list_splice_init(&session->s_cap_releases, &tmp_list);
> + lockdep_assert_held(&session->s_cap_lock);
> +
> + list_splice_init(&session->s_cap_releases, target);
> session->s_num_cap_releases = 0;
> - spin_unlock(&session->s_cap_lock);
> + dout("dispose_cap_releases mds%d\n", session->s_mds);
> +}
>
> - dout("cleanup_cap_releases mds%d\n", session->s_mds);
> - while (!list_empty(&tmp_list)) {
> +static void dispose_cap_releases(struct ceph_mds_client *mdsc,
> + struct list_head *dispose)
> +{
> + while (!list_empty(dispose)) {
> struct ceph_cap *cap;
> /* zero out the in-progress message */
> - cap = list_first_entry(&tmp_list,
> - struct ceph_cap, session_caps);
> + cap = list_first_entry(dispose, struct ceph_cap, session_caps);
> list_del(&cap->session_caps);
> ceph_put_cap(mdsc, cap);
> }
> @@ -1243,6 +1244,8 @@ static void remove_session_caps(struct ceph_mds_session *session)
> {
> struct ceph_fs_client *fsc = session->s_mdsc->fsc;
> struct super_block *sb = fsc->sb;
> + LIST_HEAD(dispose);
> +
> dout("remove_session_caps on %p\n", session);
> iterate_session_caps(session, remove_session_caps_cb, fsc);
>
> @@ -1277,10 +1280,12 @@ static void remove_session_caps(struct ceph_mds_session *session)
> }
>
> // drop cap expires and unlock s_cap_lock
> - cleanup_cap_releases(session->s_mdsc, session);
> + detach_cap_releases(session, &dispose);
>
> BUG_ON(session->s_nr_caps > 0);
> BUG_ON(!list_empty(&session->s_cap_flushing));
> + spin_unlock(&session->s_cap_lock);
> + dispose_cap_releases(session->s_mdsc, &dispose);
> }
>
> /*
> @@ -2992,6 +2997,7 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
> int s_nr_caps;
> struct ceph_pagelist *pagelist;
> struct ceph_reconnect_state recon_state;
> + LIST_HEAD(dispose);
>
> pr_info("mds%d reconnect start\n", mds);
>
> @@ -3025,7 +3031,9 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
> */
> session->s_cap_reconnect = 1;
> /* drop old cap expires; we're about to reestablish that state */
> - cleanup_cap_releases(mdsc, session);
> + detach_cap_releases(session, &dispose);
> + spin_unlock(&session->s_cap_lock);
> + dispose_cap_releases(mdsc, &dispose);
>
> /* trim unused caps to reduce MDS's cache rejoin time */
> if (mdsc->fsc->sb->s_root)
> --
> 2.13.6
>
Reviewed-by: "Yan, Zheng" <zyan@xxxxxxxxxx>
--
To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
