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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: Jeff Layton <jlayton@redhat.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Jeff Layton 2017-10-19 08:53:58 -04:00 committed by Ilya Dryomov
parent 9568c93eca
commit c8a96a31cb
1 changed files with 22 additions and 14 deletions
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36
fs/ceph/mds_client.c
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@ -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);
session->s_num_cap_releases = 0;
spin_unlock(&session->s_cap_lock);
lockdep_assert_held(&session->s_cap_lock);
dout("cleanup_cap_releases mds%d\n", session->s_mds);
while (!list_empty(&tmp_list)) {
list_splice_init(&session->s_cap_releases, target);
session->s_num_cap_releases = 0;
dout("dispose_cap_releases mds%d\n", session->s_mds);
}
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)