ceph: eliminate session->s_gen_ttl_lock

Turn s_cap_gen field into an atomic_t, and just rely on the fact that we
hold the s_mutex when changing the s_cap_ttl field.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Luis Henriques <lhenriques@suse.de>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index a5e93b1..919eada 100644 (file)
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -645,9 +645,7 @@ void ceph_add_cap(struct inode *inode,
        dout("add_cap %p mds%d cap %llx %s seq %d\n", inode,
             session->s_mds, cap_id, ceph_cap_string(issued), seq);
 
-       spin_lock(&session->s_gen_ttl_lock);
-       gen = session->s_cap_gen;
-       spin_unlock(&session->s_gen_ttl_lock);
+       gen = atomic_read(&session->s_cap_gen);
 
        cap = __get_cap_for_mds(ci, mds);
        if (!cap) {
@@ -785,10 +783,8 @@ static int __cap_is_valid(struct ceph_cap *cap)
        unsigned long ttl;
        u32 gen;
 
-       spin_lock(&cap->session->s_gen_ttl_lock);
-       gen = cap->session->s_cap_gen;
+       gen = atomic_read(&cap->session->s_cap_gen);
        ttl = cap->session->s_cap_ttl;
-       spin_unlock(&cap->session->s_gen_ttl_lock);
 
        if (cap->cap_gen < gen || time_after_eq(jiffies, ttl)) {
                dout("__cap_is_valid %p cap %p issued %s "
@@ -1182,7 +1178,8 @@ void __ceph_remove_cap(struct ceph_cap *cap, bool queue_release)
         * s_cap_gen while session is in the reconnect state.
         */
        if (queue_release &&
-           (!session->s_cap_reconnect || cap->cap_gen == session->s_cap_gen)) {
+           (!session->s_cap_reconnect ||
+            cap->cap_gen == atomic_read(&session->s_cap_gen))) {
                cap->queue_release = 1;
                if (removed) {
                        __ceph_queue_cap_release(session, cap);
@@ -3288,7 +3285,7 @@ static void handle_cap_grant(struct inode *inode,
        u64 size = le64_to_cpu(grant->size);
        u64 max_size = le64_to_cpu(grant->max_size);
        unsigned char check_caps = 0;
-       bool was_stale = cap->cap_gen < session->s_cap_gen;
+       bool was_stale = cap->cap_gen < atomic_read(&session->s_cap_gen);
        bool wake = false;
        bool writeback = false;
        bool queue_trunc = false;
@@ -3340,7 +3337,7 @@ static void handle_cap_grant(struct inode *inode,
        }
 
        /* side effects now are allowed */
-       cap->cap_gen = session->s_cap_gen;
+       cap->cap_gen = atomic_read(&session->s_cap_gen);
        cap->seq = seq;
 
        __check_cap_issue(ci, cap, newcaps);

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 973489d..6bd2ad3 100644 (file)
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1548,10 +1548,8 @@ static bool __dentry_lease_is_valid(struct ceph_dentry_info *di)
                u32 gen;
                unsigned long ttl;
 
-               spin_lock(&session->s_gen_ttl_lock);
-               gen = session->s_cap_gen;
+               gen = atomic_read(&session->s_cap_gen);
                ttl = session->s_cap_ttl;
-               spin_unlock(&session->s_gen_ttl_lock);
 
                if (di->lease_gen == gen &&
                    time_before(jiffies, ttl) &&

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 6f43542..6034821 100644 (file)
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -1124,7 +1124,7 @@ static void __update_dentry_lease(struct inode *dir, struct dentry *dentry,
                return;
        }
 
-       if (di->lease_gen == session->s_cap_gen &&
+       if (di->lease_gen == atomic_read(&session->s_cap_gen) &&
            time_before(ttl, di->time))
                return;  /* we already have a newer lease. */
 
@@ -1135,7 +1135,7 @@ static void __update_dentry_lease(struct inode *dir, struct dentry *dentry,
 
        if (!di->lease_session)
                di->lease_session = ceph_get_mds_session(session);
-       di->lease_gen = session->s_cap_gen;
+       di->lease_gen = atomic_read(&session->s_cap_gen);
        di->lease_seq = le32_to_cpu(lease->seq);
        di->lease_renew_after = half_ttl;
        di->lease_renew_from = 0;

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index ec66963..87d3be1 100644 (file)
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -749,8 +749,7 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
 
        ceph_con_init(&s->s_con, s, &mds_con_ops, &mdsc->fsc->client->msgr);
 
-       spin_lock_init(&s->s_gen_ttl_lock);
-       s->s_cap_gen = 1;
+       atomic_set(&s->s_cap_gen, 1);
        s->s_cap_ttl = jiffies - 1;
 
        spin_lock_init(&s->s_cap_lock);
@@ -1763,7 +1762,7 @@ static int wake_up_session_cb(struct inode *inode, struct ceph_cap *cap,
                ci->i_requested_max_size = 0;
                spin_unlock(&ci->i_ceph_lock);
        } else if (ev == RENEWCAPS) {
-               if (cap->cap_gen < cap->session->s_cap_gen) {
+               if (cap->cap_gen < atomic_read(&cap->session->s_cap_gen)) {
                        /* mds did not re-issue stale cap */
                        spin_lock(&ci->i_ceph_lock);
                        cap->issued = cap->implemented = CEPH_CAP_PIN;
@@ -3501,10 +3500,8 @@ static void handle_session(struct ceph_mds_session *session,
        case CEPH_SESSION_STALE:
                pr_info("mds%d caps went stale, renewing\n",
                        session->s_mds);
-               spin_lock(&session->s_gen_ttl_lock);
-               session->s_cap_gen++;
+               atomic_inc(&session->s_cap_gen);
                session->s_cap_ttl = jiffies - 1;
-               spin_unlock(&session->s_gen_ttl_lock);
                send_renew_caps(mdsc, session);
                break;
 
@@ -3773,7 +3770,7 @@ static int reconnect_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;
+       cap->cap_gen = atomic_read(&cap->session->s_cap_gen);
 
        /* These are lost when the session goes away */
        if (S_ISDIR(inode->i_mode)) {
@@ -4013,9 +4010,7 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
        dout("session %p state %s\n", session,
             ceph_session_state_name(session->s_state));
 
-       spin_lock(&session->s_gen_ttl_lock);
-       session->s_cap_gen++;
-       spin_unlock(&session->s_gen_ttl_lock);
+       atomic_inc(&session->s_cap_gen);
 
        spin_lock(&session->s_cap_lock);
        /* don't know if session is readonly */
@@ -4346,7 +4341,7 @@ static void handle_lease(struct ceph_mds_client *mdsc,
 
        case CEPH_MDS_LEASE_RENEW:
                if (di->lease_session == session &&
-                   di->lease_gen == session->s_cap_gen &&
+                   di->lease_gen == atomic_read(&session->s_cap_gen) &&
                    di->lease_renew_from &&
                    di->lease_renew_after == 0) {
                        unsigned long duration =

diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index 15c11a0..20e42d8 100644 (file)
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -186,10 +186,8 @@ struct ceph_mds_session {
 
        struct ceph_auth_handshake s_auth;
 
-       /* protected by s_gen_ttl_lock */
-       spinlock_t        s_gen_ttl_lock;
-       u32               s_cap_gen;  /* inc each time we get mds stale msg */
-       unsigned long     s_cap_ttl;  /* when session caps expire */
+       atomic_t          s_cap_gen;  /* inc each time we get mds stale msg */
+       unsigned long     s_cap_ttl;  /* when session caps expire. protected by s_mutex */
 
        /* protected by s_cap_lock */
        spinlock_t        s_cap_lock;