Commit 4d7ace02 authored by Xiubo Li's avatar Xiubo Li Committed by Ilya Dryomov
Browse files

ceph: fix mdsmap cluster available check based on laggy number 



In case the max_mds > 1 in MDS cluster and there is no any standby
MDS and all the max_mds MDSs are in up:active state, if one of the
up:active MDSs is dead, the m->m_num_laggy in kclient will be 1.
Then the mount will fail without considering other healthy MDSs.

There manybe some MDSs still "in" the cluster but not in up:active
state, we will ignore them. Only when all the up:active MDSs in
the cluster are laggy will treat the cluster as not be available.

In case decreasing the max_mds, the cluster will not stop the extra
up:active MDSs immediately and there will be a latency. During it
the up:active MDS number will be larger than the max_mds, so later
the m_info memories will 100% be reallocated.

Here will pick out the up:active MDSs as the m_num_mds and allocate
the needed memories once.

Signed-off-by: default avatarXiubo Li <xiubli@redhat.com>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent d80865bf

fs/ceph/mdsmap.c

+27 −21
Original line number Diff line number Diff line
@@ -113,6 +113,7 @@ struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end) 
	int err;

	u8 mdsmap_v, mdsmap_cv;

	u16 mdsmap_ev;

	u32 possible_max_rank;



	m = kzalloc(sizeof(*m), GFP_NOFS);

	if (!m)
@@ -138,14 +139,30 @@ 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;



	/*

	 * pick out the active nodes as the m_num_mds, the m_num_mds

	 * maybe larger than m_max_mds when decreasing the max_mds in

	 * cluster side, in other case it should less than or equal

	 * to m_max_mds.

	 */

	m->m_num_mds = n = ceph_decode_32(p);

	m->m_num_active_mds = m->m_num_mds;



	/*

	 * the possible max rank, it maybe larger than the m->m_num_mds,

	 * for example if the mds_max == 2 in the cluster, when the MDS(0)

	 * was laggy and being replaced by a new MDS, we will temporarily

	 * receive a new mds map with n_num_mds == 1 and the active MDS(1),

	 * and the mds rank >= m->m_num_mds.

	 */

	possible_max_rank = max((u32)m->m_num_mds, m->m_max_mds);



	m->m_info = kcalloc(m->m_num_mds, sizeof(*m->m_info), GFP_NOFS);

	if (!m->m_info)

		goto nomem;



	/* pick out active nodes from mds_info (state > 0) */

	n = ceph_decode_32(p);

	for (i = 0; i < n; i++) {

		u64 global_id;

		u32 namelen;
@@ -215,18 +232,15 @@ struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end) 
		     ceph_mds_state_name(state),

		     laggy ? "(laggy)" : "");



		if (mds < 0 || state <= 0)

		if (mds < 0 || mds >= possible_max_rank) {

			pr_warn("mdsmap_decode got incorrect mds(%d)\n", mds);

			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;

		if (state <= 0) {

			pr_warn("mdsmap_decode got incorrect state(%s)\n",

				ceph_mds_state_name(state));

			continue;

		}



		info = &m->m_info[mds];
@@ -247,14 +261,6 @@ 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);
@@ -396,7 +402,7 @@ bool ceph_mdsmap_is_cluster_available(struct ceph_mdsmap *m) 
		return false;

	if (m->m_damaged)

		return false;

	if (m->m_num_laggy > 0)

	if (m->m_num_laggy == m->m_num_active_mds)

		return false;

	for (i = 0; i < m->m_num_mds; i++) {

		if (m->m_info[i].state == CEPH_MDS_STATE_ACTIVE)

include/linux/ceph/mdsmap.h

+3 −2
Original line number Diff line number Diff line
@@ -25,8 +25,9 @@ struct ceph_mdsmap { 
	u32 m_session_timeout;          /* seconds */

	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;

	u32 m_max_mds;			/* expected up:active mds number */

	int m_num_active_mds;		/* actual up:active mds number */

	int m_num_mds;                  /* size of m_info array */

	struct ceph_mds_info *m_info;



	/* which object pools file data can be stored in */

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