From 99a9c273b94a087f8feaec6c5ffbe3205a2dbe51 Mon Sep 17 00:00:00 2001 From: "Yan, Zheng" Date: Sun, 22 Sep 2013 11:08:14 +0800 Subject: [PATCH] ceph: handle race between cap reconnect and cap release When a cap get released while composing the cap reconnect message. We should skip queuing the release message if the cap hasn't been added to the cap reconnect message. Signed-off-by: Yan, Zheng Reviewed-by: Sage Weil --- fs/ceph/caps.c | 8 +++++++- fs/ceph/mds_client.c | 21 ++++++++++++++++++--- fs/ceph/mds_client.h | 1 + 3 files changed, 26 insertions(+), 4 deletions(-) diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index d2d6e40e7345..3c0a4bd74996 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -909,7 +909,13 @@ void __ceph_remove_cap(struct ceph_cap *cap, bool queue_release) /* remove from session list */ spin_lock(&session->s_cap_lock); - if (queue_release) + /* + * s_cap_reconnect is protected by s_cap_lock. no one changes + * s_cap_gen while session is in the reconnect state. + */ + if (queue_release && + (!session->s_cap_reconnect || + cap->cap_gen == session->s_cap_gen)) __queue_cap_release(session, ci->i_vino.ino, cap->cap_id, cap->mseq, cap->issue_seq); diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 4a93d69abc8b..6d953ab0ac06 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -444,6 +444,7 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc, INIT_LIST_HEAD(&s->s_waiting); INIT_LIST_HEAD(&s->s_unsafe); s->s_num_cap_releases = 0; + s->s_cap_reconnect = 0; s->s_cap_iterator = NULL; INIT_LIST_HEAD(&s->s_cap_releases); INIT_LIST_HEAD(&s->s_cap_releases_done); @@ -1415,7 +1416,6 @@ static void discard_cap_releases(struct ceph_mds_client *mdsc, unsigned num; dout("discard_cap_releases mds%d\n", session->s_mds); - spin_lock(&session->s_cap_lock); /* zero out the in-progress message */ msg = list_first_entry(&session->s_cap_releases, @@ -1442,8 +1442,6 @@ static void discard_cap_releases(struct ceph_mds_client *mdsc, msg->front.iov_len = sizeof(*head); list_add(&msg->list_head, &session->s_cap_releases); } - - spin_unlock(&session->s_cap_lock); } /* @@ -2488,6 +2486,7 @@ static int encode_caps_cb(struct inode *inode, struct ceph_cap *cap, cap->seq = 0; /* reset cap seq */ cap->issue_seq = 0; /* and issue_seq */ cap->mseq = 0; /* and migrate_seq */ + cap->cap_gen = cap->session->s_cap_gen; if (recon_state->flock) { rec.v2.cap_id = cpu_to_le64(cap->cap_id); @@ -2611,8 +2610,20 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc, dout("session %p state %s\n", session, session_state_name(session->s_state)); + spin_lock(&session->s_gen_ttl_lock); + session->s_cap_gen++; + spin_unlock(&session->s_gen_ttl_lock); + + spin_lock(&session->s_cap_lock); + /* + * notify __ceph_remove_cap() that we are composing cap reconnect. + * If a cap get released before being added to the cap reconnect, + * __ceph_remove_cap() should skip queuing cap release. + */ + session->s_cap_reconnect = 1; /* drop old cap expires; we're about to reestablish that state */ discard_cap_releases(mdsc, session); + spin_unlock(&session->s_cap_lock); /* traverse this session's caps */ s_nr_caps = session->s_nr_caps; @@ -2627,6 +2638,10 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc, if (err < 0) goto fail; + spin_lock(&session->s_cap_lock); + session->s_cap_reconnect = 0; + spin_unlock(&session->s_cap_lock); + /* * snaprealms. we provide mds with the ino, seq (version), and * parent for all of our realms. If the mds has any newer info, diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h index c2a19fbbe517..4c053d099ae4 100644 --- a/fs/ceph/mds_client.h +++ b/fs/ceph/mds_client.h @@ -132,6 +132,7 @@ struct ceph_mds_session { struct list_head s_caps; /* all caps issued by this session */ int s_nr_caps, s_trim_caps; int s_num_cap_releases; + int s_cap_reconnect; struct list_head s_cap_releases; /* waiting cap_release messages */ struct list_head s_cap_releases_done; /* ready to send */ struct ceph_cap *s_cap_iterator; -- 2.20.1