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Commit c8a96a31 authored by Jeff Layton's avatar Jeff Layton Committed by Ilya Dryomov
Browse files

ceph: clean up spinlocking and list handling around cleanup_cap_releases() 



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: default avatarJeff Layton <jlayton@redhat.com>
Reviewed-by: default avatar"Yan, Zheng" <zyan@redhat.com>
Reviewed-by: default avatarIlya Dryomov <idryomov@gmail.com>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent 9568c93e

fs/ceph/mds_client.c

+21 −13
Original line number Diff line number Diff line
@@ -1039,22 +1039,23 @@ 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);

	}
@@ -1251,6 +1252,8 @@ 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);
@@ -1285,10 +1288,12 @@ 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);

}



/*
@@ -3015,6 +3020,7 @@ 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);
@@ -3048,7 +3054,9 @@ 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)