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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 <zheng.z.yan@intel.com>
Reviewed-by: Sage Weil <sage@inktank.com>
This commit is contained in:
Yan, Zheng 2013-09-22 11:08:14 +08:00 committed by Sage Weil
parent 44c99757fa
commit 99a9c273b9
3 changed files with 26 additions and 4 deletions
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8
fs/ceph/caps.c
View File

@ -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);

21
fs/ceph/mds_client.c
View File

@ -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,

1
fs/ceph/mds_client.h
View File

@ -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;