ceph: allow connecting to mds whose rank >= mdsmap::m_max_mds

mdsmap::m_max_mds is the expected count of active mds. It's not the
max rank of active mds. User can decrease mdsmap::m_max_mds, but does
not stop mds whose rank >= mdsmap::m_max_mds.
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/debugfs.c

@@ -22,20 +22,19 @@ static int mdsmap_show(struct seq_file *s, void *p)
 {
 	int i;
 	struct ceph_fs_client *fsc = s->private;
+	struct ceph_mdsmap *mdsmap;
 
 	if (fsc->mdsc == NULL || fsc->mdsc->mdsmap == NULL)
 		return 0;
-	seq_printf(s, "epoch %d\n", fsc->mdsc->mdsmap->m_epoch);
-	seq_printf(s, "root %d\n", fsc->mdsc->mdsmap->m_root);
-	seq_printf(s, "session_timeout %d\n",
-		       fsc->mdsc->mdsmap->m_session_timeout);
-	seq_printf(s, "session_autoclose %d\n",
-		       fsc->mdsc->mdsmap->m_session_autoclose);
-	for (i = 0; i < fsc->mdsc->mdsmap->m_max_mds; i++) {
-		struct ceph_entity_addr *addr =
-			&fsc->mdsc->mdsmap->m_info[i].addr;
-		int state = fsc->mdsc->mdsmap->m_info[i].state;
-
+	mdsmap = fsc->mdsc->mdsmap;
+	seq_printf(s, "epoch %d\n", mdsmap->m_epoch);
+	seq_printf(s, "root %d\n", mdsmap->m_root);
+	seq_printf(s, "max_mds %d\n", mdsmap->m_max_mds);
+	seq_printf(s, "session_timeout %d\n", mdsmap->m_session_timeout);
+	seq_printf(s, "session_autoclose %d\n", mdsmap->m_session_autoclose);
+	for (i = 0; i < mdsmap->m_num_mds; i++) {
+		struct ceph_entity_addr *addr = &mdsmap->m_info[i].addr;
+		int state = mdsmap->m_info[i].state;
 		seq_printf(s, "\tmds%d\t%s\t(%s)\n", i,
 			       ceph_pr_addr(&addr->in_addr),
 			       ceph_mds_state_name(state));

fs/ceph/mds_client.c

@@ -441,7 +441,7 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
 {
 	struct ceph_mds_session *s;
 
-	if (mds >= mdsc->mdsmap->m_max_mds)
+	if (mds >= mdsc->mdsmap->m_num_mds)
 		return ERR_PTR(-EINVAL);
 
 	s = kzalloc(sizeof(*s), GFP_NOFS);
@@ -1004,7 +1004,7 @@ static void __open_export_target_sessions(struct ceph_mds_client *mdsc,
 	struct ceph_mds_session *ts;
 	int i, mds = session->s_mds;
 
-	if (mds >= mdsc->mdsmap->m_max_mds)
+	if (mds >= mdsc->mdsmap->m_num_mds)
 		return;
 
 	mi = &mdsc->mdsmap->m_info[mds];
@@ -3107,7 +3107,7 @@ static void check_new_map(struct ceph_mds_client *mdsc,
 	dout("check_new_map new %u old %u\n",
 	     newmap->m_epoch, oldmap->m_epoch);
 
-	for (i = 0; i < oldmap->m_max_mds && i < mdsc->max_sessions; i++) {
+	for (i = 0; i < oldmap->m_num_mds && i < mdsc->max_sessions; i++) {
 		if (mdsc->sessions[i] == NULL)
 			continue;
 		s = mdsc->sessions[i];
@@ -3121,7 +3121,7 @@ static void check_new_map(struct ceph_mds_client *mdsc,
 		     ceph_mdsmap_is_laggy(newmap, i) ? " (laggy)" : "",
 		     ceph_session_state_name(s->s_state));
 
-		if (i >= newmap->m_max_mds ||
+		if (i >= newmap->m_num_mds ||
 		    memcmp(ceph_mdsmap_get_addr(oldmap, i),
 			   ceph_mdsmap_get_addr(newmap, i),
 			   sizeof(struct ceph_entity_addr))) {
@@ -3167,7 +3167,7 @@ static void check_new_map(struct ceph_mds_client *mdsc,
 		}
 	}
 
-	for (i = 0; i < newmap->m_max_mds && i < mdsc->max_sessions; i++) {
+	for (i = 0; i < newmap->m_num_mds && i < mdsc->max_sessions; i++) {
 		s = mdsc->sessions[i];
 		if (!s)
 			continue;

fs/ceph/mdsmap.c

@@ -22,11 +22,11 @@ int ceph_mdsmap_get_random_mds(struct ceph_mdsmap *m)
 	int i;
 
 	/* special case for one mds */
-	if (1 == m->m_max_mds && m->m_info[0].state > 0)
+	if (1 == m->m_num_mds && m->m_info[0].state > 0)
 		return 0;
 
 	/* count */
-	for (i = 0; i < m->m_max_mds; i++)
+	for (i = 0; i < m->m_num_mds; i++)
 		if (m->m_info[i].state > 0)
 			n++;
 	if (n == 0)
@@ -135,8 +135,9 @@ struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end)
 	m->m_session_autoclose = ceph_decode_32(p);
 	m->m_max_file_size = ceph_decode_64(p);
 	m->m_max_mds = ceph_decode_32(p);
+	m->m_num_mds = m->m_max_mds;
 
-	m->m_info = kcalloc(m->m_max_mds, sizeof(*m->m_info), GFP_NOFS);
+	m->m_info = kcalloc(m->m_num_mds, sizeof(*m->m_info), GFP_NOFS);
 	if (m->m_info == NULL)
 		goto nomem;
 
@@ -207,9 +208,20 @@ struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end)
 		     ceph_pr_addr(&addr.in_addr),
 		     ceph_mds_state_name(state));
 
-		if (mds < 0 || mds >= m->m_max_mds || state <= 0)
+		if (mds < 0 || state <= 0)
 			continue;
 
+		if (mds >= m->m_num_mds) {
+			int new_num = max(mds + 1, m->m_num_mds * 2);
+			void *new_m_info = krealloc(m->m_info,
+						new_num * sizeof(*m->m_info),
+						GFP_NOFS | __GFP_ZERO);
+			if (!new_m_info)
+				goto nomem;
+			m->m_info = new_m_info;
+			m->m_num_mds = new_num;
+		}
+
 		info = &m->m_info[mds];
 		info->global_id = global_id;
 		info->state = state;
@@ -229,6 +241,14 @@ struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end)
 			info->export_targets = NULL;
 		}
 	}
+	if (m->m_num_mds > m->m_max_mds) {
+		/* find max up mds */
+		for (i = m->m_num_mds; i >= m->m_max_mds; i--) {
+			if (i == 0 || m->m_info[i-1].state > 0)
+				break;
+		}
+		m->m_num_mds = i;
+	}
 
 	/* pg_pools */
 	ceph_decode_32_safe(p, end, n, bad);
@@ -270,12 +290,22 @@ struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end)
 
 		for (i = 0; i < n; i++) {
 			s32 mds = ceph_decode_32(p);
-			if (mds >= 0 && mds < m->m_max_mds) {
+			if (mds >= 0 && mds < m->m_num_mds) {
 				if (m->m_info[mds].laggy)
 					num_laggy++;
 			}
 		}
 		m->m_num_laggy = num_laggy;
+
+		if (n > m->m_num_mds) {
+			void *new_m_info = krealloc(m->m_info,
+						    n * sizeof(*m->m_info),
+						    GFP_NOFS | __GFP_ZERO);
+			if (!new_m_info)
+				goto nomem;
+			m->m_info = new_m_info;
+		}
+		m->m_num_mds = n;
 	}
 
 	/* inc */
@@ -341,7 +371,7 @@ void ceph_mdsmap_destroy(struct ceph_mdsmap *m)
 {
 	int i;
 
-	for (i = 0; i < m->m_max_mds; i++)
+	for (i = 0; i < m->m_num_mds; i++)
 		kfree(m->m_info[i].export_targets);
 	kfree(m->m_info);
 	kfree(m->m_data_pg_pools);
@@ -357,7 +387,7 @@ bool ceph_mdsmap_is_cluster_available(struct ceph_mdsmap *m)
 		return false;
 	if (m->m_num_laggy > 0)
 		return false;
-	for (i = 0; i < m->m_max_mds; i++) {
+	for (i = 0; i < m->m_num_mds; i++) {
 		if (m->m_info[i].state == CEPH_MDS_STATE_ACTIVE)
 			nr_active++;
 	}

include/linux/ceph/mdsmap.h

@@ -25,6 +25,7 @@ struct ceph_mdsmap {
 	u32 m_session_autoclose;        /* seconds */
 	u64 m_max_file_size;
 	u32 m_max_mds;                  /* size of m_addr, m_state arrays */
+	int m_num_mds;
 	struct ceph_mds_info *m_info;
 
 	/* which object pools file data can be stored in */
@@ -40,7 +41,7 @@ struct ceph_mdsmap {
 static inline struct ceph_entity_addr *
 ceph_mdsmap_get_addr(struct ceph_mdsmap *m, int w)
 {
-	if (w >= m->m_max_mds)
+	if (w >= m->m_num_mds)
 		return NULL;
 	return &m->m_info[w].addr;
 }
@@ -48,14 +49,14 @@ ceph_mdsmap_get_addr(struct ceph_mdsmap *m, int w)
 static inline int ceph_mdsmap_get_state(struct ceph_mdsmap *m, int w)
 {
 	BUG_ON(w < 0);
-	if (w >= m->m_max_mds)
+	if (w >= m->m_num_mds)
 		return CEPH_MDS_STATE_DNE;
 	return m->m_info[w].state;
 }
 
 static inline bool ceph_mdsmap_is_laggy(struct ceph_mdsmap *m, int w)
 {
-	if (w >= 0 && w < m->m_max_mds)
+	if (w >= 0 && w < m->m_num_mds)
 		return m->m_info[w].laggy;
 	return false;
 }