ceph: delete stale dentry when last reference is dropped

introduce ceph_d_delete(), which checks if dentry has valid lease.

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

4 files changed, 104 insertions, 32 deletions

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 82928cea0209..f34a57f56c72 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1139,45 +1139,59 @@ void ceph_invalidate_dentry_lease(struct dentry *dentry)
  * Check if dentry lease is valid.  If not, delete the lease.  Try to
  * renew if the least is more than half up.
  */
+static bool __dentry_lease_is_valid(struct ceph_dentry_info *di)
+{
+        struct ceph_mds_session *session;
+
+        if (!di->lease_gen)
+                return false;
+
+        session = di->lease_session;
+        if (session) {
+                u32 gen;
+                unsigned long ttl;
+
+                spin_lock(&session->s_gen_ttl_lock);
+                gen = 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) &&
+                    time_before(jiffies, di->time))
+                        return true;
+        }
+        di->lease_gen = 0;
+        return false;
+}
+
 static int dentry_lease_is_valid(struct dentry *dentry, unsigned int flags,
                                  struct inode *dir)
 {
         struct ceph_dentry_info *di;
-        struct ceph_mds_session *s;
-        int valid = 0;
-        u32 gen;
-        unsigned long ttl;
         struct ceph_mds_session *session = NULL;
         u32 seq = 0;
+        int valid = 0;
 
         spin_lock(&dentry->d_lock);
         di = ceph_dentry(dentry);
-        if (di && di->lease_session) {
-                s = di->lease_session;
-                spin_lock(&s->s_gen_ttl_lock);
-                gen = s->s_cap_gen;
-                ttl = s->s_cap_ttl;
-                spin_unlock(&s->s_gen_ttl_lock);
+        if (di && __dentry_lease_is_valid(di)) {
+                valid = 1;
 
-                if (di->lease_gen == gen &&
-                    time_before(jiffies, di->time) &&
-                    time_before(jiffies, ttl)) {
-                        valid = 1;
-                        if (di->lease_renew_after &&
-                            time_after(jiffies, di->lease_renew_after)) {
-                                /*
-                                 * We should renew. If we're in RCU walk mode
-                                 * though, we can't do that so just return
-                                 * -ECHILD.
-                                 */
-                                if (flags & LOOKUP_RCU) {
-                                        valid = -ECHILD;
-                                } else {
-                                        session = ceph_get_mds_session(s);
-                                        seq = di->lease_seq;
-                                        di->lease_renew_after = 0;
-                                        di->lease_renew_from = jiffies;
-                                }
+                if (di->lease_renew_after &&
+                    time_after(jiffies, di->lease_renew_after)) {
+                        /*
+                         * We should renew. If we're in RCU walk mode
+                         * though, we can't do that so just return
+                         * -ECHILD.
+                         */
+                        if (flags & LOOKUP_RCU) {
+                                valid = -ECHILD;
+                        } else {
+                                session = ceph_get_mds_session(di->lease_session);
+                                seq = di->lease_seq;
+                                di->lease_renew_after = 0;
+                                di->lease_renew_from = jiffies;
                         }
                 }
         }
@@ -1193,6 +1207,38 @@ static int dentry_lease_is_valid(struct dentry *dentry, unsigned int flags,
 }
 
 /*
+ * Called under dentry->d_lock.
+ */
+static int __dir_lease_try_check(const struct dentry *dentry)
+{
+        struct ceph_dentry_info *di = ceph_dentry(dentry);
+        struct inode *dir;
+        struct ceph_inode_info *ci;
+        int valid = 0;
+
+        if (!di->lease_shared_gen)
+                return 0;
+        if (IS_ROOT(dentry))
+                return 0;
+
+        dir = d_inode(dentry->d_parent);
+        ci = ceph_inode(dir);
+
+        if (spin_trylock(&ci->i_ceph_lock)) {
+                if (atomic_read(&ci->i_shared_gen) == di->lease_shared_gen &&
+                    __ceph_caps_issued_mask(ci, CEPH_CAP_FILE_SHARED, 0))
+                        valid = 1;
+                spin_unlock(&ci->i_ceph_lock);
+        } else {
+                valid = -EBUSY;
+        }
+
+        if (!valid)
+                di->lease_shared_gen = 0;
+        return valid;
+}
+
+/*
  * Check if directory-wide content lease/cap is valid.
  */
 static int dir_lease_is_valid(struct inode *dir, struct dentry *dentry)
@@ -1309,6 +1355,31 @@ static int ceph_d_revalidate(struct dentry *dentry, unsigned int flags)
 }
 
 /*
+ * Delete unused dentry that doesn't have valid lease
+ *
+ * Called under dentry->d_lock.
+ */
+static int ceph_d_delete(const struct dentry *dentry)
+{
+        struct ceph_dentry_info *di;
+
+        /* won't release caps */
+        if (d_really_is_negative(dentry))
+                return 0;
+        if (ceph_snap(d_inode(dentry)) != CEPH_NOSNAP)
+                return 0;
+        /* vaild lease? */
+        di = ceph_dentry(dentry);
+        if (di) {
+                if (__dentry_lease_is_valid(di))
+                        return 0;
+                if (__dir_lease_try_check(dentry))
+                        return 0;
+        }
+        return 1;
+}
+
+/*
  * Release our ceph_dentry_info.
  */
 static void ceph_d_release(struct dentry *dentry)
@@ -1531,6 +1602,7 @@ const struct inode_operations ceph_snapdir_iops = {
 
 const struct dentry_operations ceph_dentry_ops = {
         .d_revalidate = ceph_d_revalidate,
+        .d_delete = ceph_d_delete,
         .d_release = ceph_d_release,
         .d_prune = ceph_d_prune,
         .d_init = ceph_d_init,
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index f588b2d7b598..f75476e94d75 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -497,7 +497,7 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
         ci->i_wrbuffer_ref = 0;
         ci->i_wrbuffer_ref_head = 0;
         atomic_set(&ci->i_filelock_ref, 0);
-        atomic_set(&ci->i_shared_gen, 0);
+        atomic_set(&ci->i_shared_gen, 1);
         ci->i_rdcache_gen = 0;
         ci->i_rdcache_revoking = 0;
 
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index c9d4561336fc..99d6e805668c 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -621,7 +621,7 @@ 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 = 0;
+        s->s_cap_gen = 1;
         s->s_cap_ttl = jiffies - 1;
 
         spin_lock_init(&s->s_cap_lock);
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index c4a79eadc55a..c0654e613fc0 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -594,7 +594,7 @@ extern u32 ceph_choose_frag(struct ceph_inode_info *ci, u32 v,
                             struct ceph_inode_frag *pfrag,
                             int *found);
 
-static inline struct ceph_dentry_info *ceph_dentry(struct dentry *dentry)
+static inline struct ceph_dentry_info *ceph_dentry(const struct dentry *dentry)
 {
         return (struct ceph_dentry_info *)dentry->d_fsdata;
 }