staging: add Lustre file system client support

Lustre is the most deployed distributed file system
in the HPC (High Performance Computing) world. The patch
adds its client side support.

The code is not very clean and needs to live in drivers/staging
for some time for continuing cleanup work. See
drivers/staging/lustre/TODO for details.

The code is based on Lustre master commit faefbfc04

commit faefbfc0460bc00f2ee4c1c1c86aa1e39b9eea49
Author: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Date:   Tue Apr 30 23:05:21 2013 +0400

    LU-3244 utils: tunefs.lustre should preserve virgin label

Plus a few under-review patches on Whamcloud gerrit:
3.8 kernel support:
http://review.whamcloud.com/#change,5973
http://review.whamcloud.com/#change,5974
http://review.whamcloud.com/#change,5768
http://review.whamcloud.com/#change,5781
http://review.whamcloud.com/#change,5763
http://review.whamcloud.com/#change,5613
http://review.whamcloud.com/#change,5655

3.9 kernel support:
http://review.whamcloud.com/#change,5898
http://review.whamcloud.com/#change,5899

Kconfig/Kbuild:
http://review.whamcloud.com/#change,4646
http://review.whamcloud.com/#change,4644

libcfs cleanup:
http://review.whamcloud.com/#change,2831
http://review.whamcloud.com/#change,4775
http://review.whamcloud.com/#change,4776
http://review.whamcloud.com/#change,4777
http://review.whamcloud.com/#change,4778
http://review.whamcloud.com/#change,4779
http://review.whamcloud.com/#change,4780

All starting/trailing whitespaces are removed, to match kernel
coding style. Also ran scripts/cleanfile on all lustre source files.

[maked the Kconfig depend on BROKEN as the recent procfs changes causes
this to fail - gregkh]

Signed-off-by: Peng Tao <tao.peng@emc.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 938 insertions, 0 deletions

diff --git a/drivers/staging/lustre/lnet/lnet/lib-ptl.c b/drivers/staging/lustre/lnet/lnet/lib-ptl.c
new file mode 100644
index 000000000000..9b9e7d3139b0
--- /dev/null
+++ b/drivers/staging/lustre/lnet/lnet/lib-ptl.c
@@ -0,0 +1,938 @@
+/*
+ * GPL HEADER START
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License version 2 for more details (a copy is included
+ * in the LICENSE file that accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA
+ *
+ * GPL HEADER END
+ */
+/*
+ * Copyright (c) 2012, Intel Corporation.
+ */
+/*
+ * This file is part of Lustre, http://www.lustre.org/
+ * Lustre is a trademark of Sun Microsystems, Inc.
+ *
+ * lnet/lnet/lib-ptl.c
+ *
+ * portal & match routines
+ *
+ * Author: liang@whamcloud.com
+ */
+
+#define DEBUG_SUBSYSTEM S_LNET
+
+#include <linux/lnet/lib-lnet.h>
+
+/* NB: add /proc interfaces in upcoming patches */
+int	portal_rotor	= LNET_PTL_ROTOR_HASH_RT;
+CFS_MODULE_PARM(portal_rotor, "i", int, 0644,
+		"redirect PUTs to different cpu-partitions");
+
+static int
+lnet_ptl_match_type(unsigned int index, lnet_process_id_t match_id,
+		    __u64 mbits, __u64 ignore_bits)
+{
+	struct lnet_portal	*ptl = the_lnet.ln_portals[index];
+	int			unique;
+
+	unique = ignore_bits == 0 &&
+		 match_id.nid != LNET_NID_ANY &&
+		 match_id.pid != LNET_PID_ANY;
+
+	LASSERT(!lnet_ptl_is_unique(ptl) || !lnet_ptl_is_wildcard(ptl));
+
+	/* prefer to check w/o any lock */
+	if (likely(lnet_ptl_is_unique(ptl) || lnet_ptl_is_wildcard(ptl)))
+		goto match;
+
+	/* unset, new portal */
+	lnet_ptl_lock(ptl);
+	/* check again with lock */
+	if (unlikely(lnet_ptl_is_unique(ptl) || lnet_ptl_is_wildcard(ptl))) {
+		lnet_ptl_unlock(ptl);
+		goto match;
+	}
+
+	/* still not set */
+	if (unique)
+		lnet_ptl_setopt(ptl, LNET_PTL_MATCH_UNIQUE);
+	else
+		lnet_ptl_setopt(ptl, LNET_PTL_MATCH_WILDCARD);
+
+	lnet_ptl_unlock(ptl);
+
+	return 1;
+
+ match:
+	if ((lnet_ptl_is_unique(ptl) && !unique) ||
+	    (lnet_ptl_is_wildcard(ptl) && unique))
+		return 0;
+	return 1;
+}
+
+static void
+lnet_ptl_enable_mt(struct lnet_portal *ptl, int cpt)
+{
+	struct lnet_match_table	*mtable = ptl->ptl_mtables[cpt];
+	int			i;
+
+	/* with hold of both lnet_res_lock(cpt) and lnet_ptl_lock */
+	LASSERT(lnet_ptl_is_wildcard(ptl));
+
+	mtable->mt_enabled = 1;
+
+	ptl->ptl_mt_maps[ptl->ptl_mt_nmaps] = cpt;
+	for (i = ptl->ptl_mt_nmaps - 1; i >= 0; i--) {
+		LASSERT(ptl->ptl_mt_maps[i] != cpt);
+		if (ptl->ptl_mt_maps[i] < cpt)
+			break;
+
+		/* swap to order */
+		ptl->ptl_mt_maps[i + 1] = ptl->ptl_mt_maps[i];
+		ptl->ptl_mt_maps[i] = cpt;
+	}
+
+	ptl->ptl_mt_nmaps++;
+}
+
+static void
+lnet_ptl_disable_mt(struct lnet_portal *ptl, int cpt)
+{
+	struct lnet_match_table	*mtable = ptl->ptl_mtables[cpt];
+	int			i;
+
+	/* with hold of both lnet_res_lock(cpt) and lnet_ptl_lock */
+	LASSERT(lnet_ptl_is_wildcard(ptl));
+
+	if (LNET_CPT_NUMBER == 1)
+		return; /* never disable the only match-table */
+
+	mtable->mt_enabled = 0;
+
+	LASSERT(ptl->ptl_mt_nmaps > 0 &&
+		ptl->ptl_mt_nmaps <= LNET_CPT_NUMBER);
+
+	/* remove it from mt_maps */
+	ptl->ptl_mt_nmaps--;
+	for (i = 0; i < ptl->ptl_mt_nmaps; i++) {
+		if (ptl->ptl_mt_maps[i] >= cpt) /* overwrite it */
+			ptl->ptl_mt_maps[i] = ptl->ptl_mt_maps[i + 1];
+	}
+}
+
+static int
+lnet_try_match_md(lnet_libmd_t *md,
+		  struct lnet_match_info *info, struct lnet_msg *msg)
+{
+	/* ALWAYS called holding the lnet_res_lock, and can't lnet_res_unlock;
+	 * lnet_match_blocked_msg() relies on this to avoid races */
+	unsigned int	offset;
+	unsigned int	mlength;
+	lnet_me_t	*me = md->md_me;
+
+	/* MD exhausted */
+	if (lnet_md_exhausted(md))
+		return LNET_MATCHMD_NONE | LNET_MATCHMD_EXHAUSTED;
+
+	/* mismatched MD op */
+	if ((md->md_options & info->mi_opc) == 0)
+		return LNET_MATCHMD_NONE;
+
+	/* mismatched ME nid/pid? */
+	if (me->me_match_id.nid != LNET_NID_ANY &&
+	    me->me_match_id.nid != info->mi_id.nid)
+		return LNET_MATCHMD_NONE;
+
+	if (me->me_match_id.pid != LNET_PID_ANY &&
+	    me->me_match_id.pid != info->mi_id.pid)
+		return LNET_MATCHMD_NONE;
+
+	/* mismatched ME matchbits? */
+	if (((me->me_match_bits ^ info->mi_mbits) & ~me->me_ignore_bits) != 0)
+		return LNET_MATCHMD_NONE;
+
+	/* Hurrah! This _is_ a match; check it out... */
+
+	if ((md->md_options & LNET_MD_MANAGE_REMOTE) == 0)
+		offset = md->md_offset;
+	else
+		offset = info->mi_roffset;
+
+	if ((md->md_options & LNET_MD_MAX_SIZE) != 0) {
+		mlength = md->md_max_size;
+		LASSERT(md->md_offset + mlength <= md->md_length);
+	} else {
+		mlength = md->md_length - offset;
+	}
+
+	if (info->mi_rlength <= mlength) {	/* fits in allowed space */
+		mlength = info->mi_rlength;
+	} else if ((md->md_options & LNET_MD_TRUNCATE) == 0) {
+		/* this packet _really_ is too big */
+		CERROR("Matching packet from %s, match "LPU64
+		       " length %d too big: %d left, %d allowed\n",
+		       libcfs_id2str(info->mi_id), info->mi_mbits,
+		       info->mi_rlength, md->md_length - offset, mlength);
+
+		return LNET_MATCHMD_DROP;
+	}
+
+	/* Commit to this ME/MD */
+	CDEBUG(D_NET, "Incoming %s index %x from %s of "
+	       "length %d/%d into md "LPX64" [%d] + %d\n",
+	       (info->mi_opc == LNET_MD_OP_PUT) ? "put" : "get",
+	       info->mi_portal, libcfs_id2str(info->mi_id), mlength,
+	       info->mi_rlength, md->md_lh.lh_cookie, md->md_niov, offset);
+
+	lnet_msg_attach_md(msg, md, offset, mlength);
+	md->md_offset = offset + mlength;
+
+	if (!lnet_md_exhausted(md))
+		return LNET_MATCHMD_OK;
+
+	/* Auto-unlink NOW, so the ME gets unlinked if required.
+	 * We bumped md->md_refcount above so the MD just gets flagged
+	 * for unlink when it is finalized. */
+	if ((md->md_flags & LNET_MD_FLAG_AUTO_UNLINK) != 0)
+		lnet_md_unlink(md);
+
+	return LNET_MATCHMD_OK | LNET_MATCHMD_EXHAUSTED;
+}
+
+static struct lnet_match_table *
+lnet_match2mt(struct lnet_portal *ptl, lnet_process_id_t id, __u64 mbits)
+{
+	if (LNET_CPT_NUMBER == 1)
+		return ptl->ptl_mtables[0]; /* the only one */
+
+	/* if it's a unique portal, return match-table hashed by NID */
+	return lnet_ptl_is_unique(ptl) ?
+	       ptl->ptl_mtables[lnet_cpt_of_nid(id.nid)] : NULL;
+}
+
+struct lnet_match_table *
+lnet_mt_of_attach(unsigned int index, lnet_process_id_t id,
+		  __u64 mbits, __u64 ignore_bits, lnet_ins_pos_t pos)
+{
+	struct lnet_portal	*ptl;
+	struct lnet_match_table	*mtable;
+
+	/* NB: called w/o lock */
+	LASSERT(index < the_lnet.ln_nportals);
+
+	if (!lnet_ptl_match_type(index, id, mbits, ignore_bits))
+		return NULL;
+
+	ptl = the_lnet.ln_portals[index];
+
+	mtable = lnet_match2mt(ptl, id, mbits);
+	if (mtable != NULL) /* unique portal or only one match-table */
+		return mtable;
+
+	/* it's a wildcard portal */
+	switch (pos) {
+	default:
+		return NULL;
+	case LNET_INS_BEFORE:
+	case LNET_INS_AFTER:
+		/* posted by no affinity thread, always hash to specific
+		 * match-table to avoid buffer stealing which is heavy */
+		return ptl->ptl_mtables[ptl->ptl_index % LNET_CPT_NUMBER];
+	case LNET_INS_LOCAL:
+		/* posted by cpu-affinity thread */
+		return ptl->ptl_mtables[lnet_cpt_current()];
+	}
+}
+
+static struct lnet_match_table *
+lnet_mt_of_match(struct lnet_match_info *info, struct lnet_msg *msg)
+{
+	struct lnet_match_table	*mtable;
+	struct lnet_portal	*ptl;
+	int			nmaps;
+	int			rotor;
+	int			routed;
+	int			cpt;
+
+	/* NB: called w/o lock */
+	LASSERT(info->mi_portal < the_lnet.ln_nportals);
+	ptl = the_lnet.ln_portals[info->mi_portal];
+
+	LASSERT(lnet_ptl_is_wildcard(ptl) || lnet_ptl_is_unique(ptl));
+
+	mtable = lnet_match2mt(ptl, info->mi_id, info->mi_mbits);
+	if (mtable != NULL)
+		return mtable;
+
+	/* it's a wildcard portal */
+	routed = LNET_NIDNET(msg->msg_hdr.src_nid) !=
+		 LNET_NIDNET(msg->msg_hdr.dest_nid);
+
+	if (portal_rotor == LNET_PTL_ROTOR_OFF ||
+	    (portal_rotor != LNET_PTL_ROTOR_ON && !routed)) {
+		cpt = lnet_cpt_current();
+		if (ptl->ptl_mtables[cpt]->mt_enabled)
+			return ptl->ptl_mtables[cpt];
+	}
+
+	rotor = ptl->ptl_rotor++; /* get round-robin factor */
+	if (portal_rotor == LNET_PTL_ROTOR_HASH_RT && routed)
+		cpt = lnet_cpt_of_nid(msg->msg_hdr.src_nid);
+	else
+		cpt = rotor % LNET_CPT_NUMBER;
+
+	if (!ptl->ptl_mtables[cpt]->mt_enabled) {
+		/* is there any active entry for this portal? */
+		nmaps = ptl->ptl_mt_nmaps;
+		/* map to an active mtable to avoid heavy "stealing" */
+		if (nmaps != 0) {
+			/* NB: there is possibility that ptl_mt_maps is being
+			 * changed because we are not under protection of
+			 * lnet_ptl_lock, but it shouldn't hurt anything */
+			cpt = ptl->ptl_mt_maps[rotor % nmaps];
+		}
+	}
+
+	return ptl->ptl_mtables[cpt];
+}
+
+static int
+lnet_mt_test_exhausted(struct lnet_match_table *mtable, int pos)
+{
+	__u64	*bmap;
+	int	i;
+
+	if (!lnet_ptl_is_wildcard(the_lnet.ln_portals[mtable->mt_portal]))
+		return 0;
+
+	if (pos < 0) { /* check all bits */
+		for (i = 0; i < LNET_MT_EXHAUSTED_BMAP; i++) {
+			if (mtable->mt_exhausted[i] != (__u64)(-1))
+				return 0;
+		}
+		return 1;
+	}
+
+	LASSERT(pos <= LNET_MT_HASH_IGNORE);
+	/* mtable::mt_mhash[pos] is marked as exhausted or not */
+	bmap = &mtable->mt_exhausted[pos >> LNET_MT_BITS_U64];
+	pos &= (1 << LNET_MT_BITS_U64) - 1;
+
+	return ((*bmap) & (1ULL << pos)) != 0;
+}
+
+static void
+lnet_mt_set_exhausted(struct lnet_match_table *mtable, int pos, int exhausted)
+{
+	__u64	*bmap;
+
+	LASSERT(lnet_ptl_is_wildcard(the_lnet.ln_portals[mtable->mt_portal]));
+	LASSERT(pos <= LNET_MT_HASH_IGNORE);
+
+	/* set mtable::mt_mhash[pos] as exhausted/non-exhausted */
+	bmap = &mtable->mt_exhausted[pos >> LNET_MT_BITS_U64];
+	pos &= (1 << LNET_MT_BITS_U64) - 1;
+
+	if (!exhausted)
+		*bmap &= ~(1ULL << pos);
+	else
+		*bmap |= 1ULL << pos;
+}
+
+struct list_head *
+lnet_mt_match_head(struct lnet_match_table *mtable,
+		   lnet_process_id_t id, __u64 mbits)
+{
+	struct lnet_portal *ptl = the_lnet.ln_portals[mtable->mt_portal];
+
+	if (lnet_ptl_is_wildcard(ptl)) {
+		return &mtable->mt_mhash[mbits & LNET_MT_HASH_MASK];
+	} else {
+		unsigned long hash = mbits + id.nid + id.pid;
+
+		LASSERT(lnet_ptl_is_unique(ptl));
+		hash = cfs_hash_long(hash, LNET_MT_HASH_BITS);
+		return &mtable->mt_mhash[hash];
+	}
+}
+
+int
+lnet_mt_match_md(struct lnet_match_table *mtable,
+		 struct lnet_match_info *info, struct lnet_msg *msg)
+{
+	struct list_head		*head;
+	lnet_me_t		*me;
+	lnet_me_t		*tmp;
+	int			exhausted = 0;
+	int			rc;
+
+	/* any ME with ignore bits? */
+	if (!list_empty(&mtable->mt_mhash[LNET_MT_HASH_IGNORE]))
+		head = &mtable->mt_mhash[LNET_MT_HASH_IGNORE];
+	else
+		head = lnet_mt_match_head(mtable, info->mi_id, info->mi_mbits);
+ again:
+	/* NB: only wildcard portal needs to return LNET_MATCHMD_EXHAUSTED */
+	if (lnet_ptl_is_wildcard(the_lnet.ln_portals[mtable->mt_portal]))
+		exhausted = LNET_MATCHMD_EXHAUSTED;
+
+	list_for_each_entry_safe(me, tmp, head, me_list) {
+		/* ME attached but MD not attached yet */
+		if (me->me_md == NULL)
+			continue;
+
+		LASSERT(me == me->me_md->md_me);
+
+		rc = lnet_try_match_md(me->me_md, info, msg);
+		if ((rc & LNET_MATCHMD_EXHAUSTED) == 0)
+			exhausted = 0; /* mlist is not empty */
+
+		if ((rc & LNET_MATCHMD_FINISH) != 0) {
+			/* don't return EXHAUSTED bit because we don't know
+			 * whether the mlist is empty or not */
+			return rc & ~LNET_MATCHMD_EXHAUSTED;
+		}
+	}
+
+	if (exhausted == LNET_MATCHMD_EXHAUSTED) { /* @head is exhausted */
+		lnet_mt_set_exhausted(mtable, head - mtable->mt_mhash, 1);
+		if (!lnet_mt_test_exhausted(mtable, -1))
+			exhausted = 0;
+	}
+
+	if (exhausted == 0 && head == &mtable->mt_mhash[LNET_MT_HASH_IGNORE]) {
+		head = lnet_mt_match_head(mtable, info->mi_id, info->mi_mbits);
+		goto again; /* re-check MEs w/o ignore-bits */
+	}
+
+	if (info->mi_opc == LNET_MD_OP_GET ||
+	    !lnet_ptl_is_lazy(the_lnet.ln_portals[info->mi_portal]))
+		return LNET_MATCHMD_DROP | exhausted;
+
+	return LNET_MATCHMD_NONE | exhausted;
+}
+
+static int
+lnet_ptl_match_early(struct lnet_portal *ptl, struct lnet_msg *msg)
+{
+	int	rc;
+
+	/* message arrived before any buffer posting on this portal,
+	 * simply delay or drop this message */
+	if (likely(lnet_ptl_is_wildcard(ptl) || lnet_ptl_is_unique(ptl)))
+		return 0;
+
+	lnet_ptl_lock(ptl);
+	/* check it again with hold of lock */
+	if (lnet_ptl_is_wildcard(ptl) || lnet_ptl_is_unique(ptl)) {
+		lnet_ptl_unlock(ptl);
+		return 0;
+	}
+
+	if (lnet_ptl_is_lazy(ptl)) {
+		if (msg->msg_rx_ready_delay) {
+			msg->msg_rx_delayed = 1;
+			list_add_tail(&msg->msg_list,
+					  &ptl->ptl_msg_delayed);
+		}
+		rc = LNET_MATCHMD_NONE;
+	} else {
+		rc = LNET_MATCHMD_DROP;
+	}
+
+	lnet_ptl_unlock(ptl);
+	return rc;
+}
+
+static int
+lnet_ptl_match_delay(struct lnet_portal *ptl,
+		     struct lnet_match_info *info, struct lnet_msg *msg)
+{
+	int	first = ptl->ptl_mt_maps[0]; /* read w/o lock */
+	int	rc = 0;
+	int	i;
+
+	/* steal buffer from other CPTs, and delay it if nothing to steal,
+	 * this function is more expensive than a regular match, but we
+	 * don't expect it can happen a lot */
+	LASSERT(lnet_ptl_is_wildcard(ptl));
+
+	for (i = 0; i < LNET_CPT_NUMBER; i++) {
+		struct lnet_match_table *mtable;
+		int			cpt;
+
+		cpt = (first + i) % LNET_CPT_NUMBER;
+		mtable = ptl->ptl_mtables[cpt];
+		if (i != 0 && i != LNET_CPT_NUMBER - 1 && !mtable->mt_enabled)
+			continue;
+
+		lnet_res_lock(cpt);
+		lnet_ptl_lock(ptl);
+
+		if (i == 0) { /* the first try, attach on stealing list */
+			list_add_tail(&msg->msg_list,
+					  &ptl->ptl_msg_stealing);
+		}
+
+		if (!list_empty(&msg->msg_list)) { /* on stealing list */
+			rc = lnet_mt_match_md(mtable, info, msg);
+
+			if ((rc & LNET_MATCHMD_EXHAUSTED) != 0 &&
+			    mtable->mt_enabled)
+				lnet_ptl_disable_mt(ptl, cpt);
+
+			if ((rc & LNET_MATCHMD_FINISH) != 0)
+				list_del_init(&msg->msg_list);
+
+		} else {
+			/* could be matched by lnet_ptl_attach_md()
+			 * which is called by another thread */
+			rc = msg->msg_md == NULL ?
+			     LNET_MATCHMD_DROP : LNET_MATCHMD_OK;
+		}
+
+		if (!list_empty(&msg->msg_list) && /* not matched yet */
+		    (i == LNET_CPT_NUMBER - 1 || /* the last CPT */
+		     ptl->ptl_mt_nmaps == 0 ||   /* no active CPT */
+		     (ptl->ptl_mt_nmaps == 1 &&  /* the only active CPT */
+		      ptl->ptl_mt_maps[0] == cpt))) {
+			/* nothing to steal, delay or drop */
+			list_del_init(&msg->msg_list);
+
+			if (lnet_ptl_is_lazy(ptl)) {
+				msg->msg_rx_delayed = 1;
+				list_add_tail(&msg->msg_list,
+						  &ptl->ptl_msg_delayed);
+				rc = LNET_MATCHMD_NONE;
+			} else {
+				rc = LNET_MATCHMD_DROP;
+			}
+		}
+
+		lnet_ptl_unlock(ptl);
+		lnet_res_unlock(cpt);
+
+		if ((rc & LNET_MATCHMD_FINISH) != 0 || msg->msg_rx_delayed)
+			break;
+	}
+
+	return rc;
+}
+
+int
+lnet_ptl_match_md(struct lnet_match_info *info, struct lnet_msg *msg)
+{
+	struct lnet_match_table	*mtable;
+	struct lnet_portal	*ptl;
+	int			rc;
+
+	CDEBUG(D_NET, "Request from %s of length %d into portal %d "
+	       "MB="LPX64"\n", libcfs_id2str(info->mi_id),
+	       info->mi_rlength, info->mi_portal, info->mi_mbits);
+
+	if (info->mi_portal >= the_lnet.ln_nportals) {
+		CERROR("Invalid portal %d not in [0-%d]\n",
+		       info->mi_portal, the_lnet.ln_nportals);
+		return LNET_MATCHMD_DROP;
+	}
+
+	ptl = the_lnet.ln_portals[info->mi_portal];
+	rc = lnet_ptl_match_early(ptl, msg);
+	if (rc != 0) /* matched or delayed early message */
+		return rc;
+
+	mtable = lnet_mt_of_match(info, msg);
+	lnet_res_lock(mtable->mt_cpt);
+
+	if (the_lnet.ln_shutdown) {
+		rc = LNET_MATCHMD_DROP;
+		goto out1;
+	}
+
+	rc = lnet_mt_match_md(mtable, info, msg);
+	if ((rc & LNET_MATCHMD_EXHAUSTED) != 0 && mtable->mt_enabled) {
+		lnet_ptl_lock(ptl);
+		lnet_ptl_disable_mt(ptl, mtable->mt_cpt);
+		lnet_ptl_unlock(ptl);
+	}
+
+	if ((rc & LNET_MATCHMD_FINISH) != 0)	/* matched or dropping */
+		goto out1;
+
+	if (!msg->msg_rx_ready_delay)
+		goto out1;
+
+	LASSERT(lnet_ptl_is_lazy(ptl));
+	LASSERT(!msg->msg_rx_delayed);
+
+	/* NB: we don't expect "delay" can happen a lot */
+	if (lnet_ptl_is_unique(ptl) || LNET_CPT_NUMBER == 1) {
+		lnet_ptl_lock(ptl);
+
+		msg->msg_rx_delayed = 1;
+		list_add_tail(&msg->msg_list, &ptl->ptl_msg_delayed);
+
+		lnet_ptl_unlock(ptl);
+		lnet_res_unlock(mtable->mt_cpt);
+
+	} else  {
+		lnet_res_unlock(mtable->mt_cpt);
+		rc = lnet_ptl_match_delay(ptl, info, msg);
+	}
+
+	if (msg->msg_rx_delayed) {
+		CDEBUG(D_NET,
+		       "Delaying %s from %s ptl %d MB "LPX64" off %d len %d\n",
+		       info->mi_opc == LNET_MD_OP_PUT ? "PUT" : "GET",
+		       libcfs_id2str(info->mi_id), info->mi_portal,
+		       info->mi_mbits, info->mi_roffset, info->mi_rlength);
+	}
+	goto out0;
+ out1:
+	lnet_res_unlock(mtable->mt_cpt);
+ out0:
+	/* EXHAUSTED bit is only meaningful for internal functions */
+	return rc & ~LNET_MATCHMD_EXHAUSTED;
+}
+
+void
+lnet_ptl_detach_md(lnet_me_t *me, lnet_libmd_t *md)
+{
+	LASSERT(me->me_md == md && md->md_me == me);
+
+	me->me_md = NULL;
+	md->md_me = NULL;
+}
+
+/* called with lnet_res_lock held */
+void
+lnet_ptl_attach_md(lnet_me_t *me, lnet_libmd_t *md,
+		   struct list_head *matches, struct list_head *drops)
+{
+	struct lnet_portal	*ptl = the_lnet.ln_portals[me->me_portal];
+	struct lnet_match_table	*mtable;
+	struct list_head		*head;
+	lnet_msg_t		*tmp;
+	lnet_msg_t		*msg;
+	int			exhausted = 0;
+	int			cpt;
+
+	LASSERT(md->md_refcount == 0); /* a brand new MD */
+
+	me->me_md = md;
+	md->md_me = me;
+
+	cpt = lnet_cpt_of_cookie(md->md_lh.lh_cookie);
+	mtable = ptl->ptl_mtables[cpt];
+
+	if (list_empty(&ptl->ptl_msg_stealing) &&
+	    list_empty(&ptl->ptl_msg_delayed) &&
+	    !lnet_mt_test_exhausted(mtable, me->me_pos))
+		return;
+
+	lnet_ptl_lock(ptl);
+	head = &ptl->ptl_msg_stealing;
+ again:
+	list_for_each_entry_safe(msg, tmp, head, msg_list) {
+		struct lnet_match_info	info;
+		lnet_hdr_t		*hdr;
+		int			rc;
+
+		LASSERT(msg->msg_rx_delayed || head == &ptl->ptl_msg_stealing);
+
+		hdr   = &msg->msg_hdr;
+		info.mi_id.nid	= hdr->src_nid;
+		info.mi_id.pid	= hdr->src_pid;
+		info.mi_opc	= LNET_MD_OP_PUT;
+		info.mi_portal	= hdr->msg.put.ptl_index;
+		info.mi_rlength	= hdr->payload_length;
+		info.mi_roffset	= hdr->msg.put.offset;
+		info.mi_mbits	= hdr->msg.put.match_bits;
+
+		rc = lnet_try_match_md(md, &info, msg);
+
+		exhausted = (rc & LNET_MATCHMD_EXHAUSTED) != 0;
+		if ((rc & LNET_MATCHMD_NONE) != 0) {
+			if (exhausted)
+				break;
+			continue;
+		}
+
+		/* Hurrah! This _is_ a match */
+		LASSERT((rc & LNET_MATCHMD_FINISH) != 0);
+		list_del_init(&msg->msg_list);
+
+		if (head == &ptl->ptl_msg_stealing) {
+			if (exhausted)
+				break;
+			/* stealing thread will handle the message */
+			continue;
+		}
+
+		if ((rc & LNET_MATCHMD_OK) != 0) {
+			list_add_tail(&msg->msg_list, matches);
+
+			CDEBUG(D_NET, "Resuming delayed PUT from %s portal %d "
+			       "match "LPU64" offset %d length %d.\n",
+			       libcfs_id2str(info.mi_id),
+			       info.mi_portal, info.mi_mbits,
+			       info.mi_roffset, info.mi_rlength);
+		} else {
+			list_add_tail(&msg->msg_list, drops);
+		}
+
+		if (exhausted)
+			break;
+	}
+
+	if (!exhausted && head == &ptl->ptl_msg_stealing) {
+		head = &ptl->ptl_msg_delayed;
+		goto again;
+	}
+
+	if (lnet_ptl_is_wildcard(ptl) && !exhausted) {
+		lnet_mt_set_exhausted(mtable, me->me_pos, 0);
+		if (!mtable->mt_enabled)
+			lnet_ptl_enable_mt(ptl, cpt);
+	}
+
+	lnet_ptl_unlock(ptl);
+}
+
+void
+lnet_ptl_cleanup(struct lnet_portal *ptl)
+{
+	struct lnet_match_table	*mtable;
+	int			i;
+
+	if (ptl->ptl_mtables == NULL) /* uninitialized portal */
+		return;
+
+	LASSERT(list_empty(&ptl->ptl_msg_delayed));
+	LASSERT(list_empty(&ptl->ptl_msg_stealing));
+	cfs_percpt_for_each(mtable, i, ptl->ptl_mtables) {
+		struct list_head	*mhash;
+		lnet_me_t	*me;
+		int		j;
+
+		if (mtable->mt_mhash == NULL) /* uninitialized match-table */
+			continue;
+
+		mhash = mtable->mt_mhash;
+		/* cleanup ME */
+		for (j = 0; j < LNET_MT_HASH_SIZE + 1; j++) {
+			while (!list_empty(&mhash[j])) {
+				me = list_entry(mhash[j].next,
+						    lnet_me_t, me_list);
+				CERROR("Active ME %p on exit\n", me);
+				list_del(&me->me_list);
+				lnet_me_free(me);
+			}
+		}
+		/* the extra entry is for MEs with ignore bits */
+		LIBCFS_FREE(mhash, sizeof(*mhash) * (LNET_MT_HASH_SIZE + 1));
+	}
+
+	cfs_percpt_free(ptl->ptl_mtables);
+	ptl->ptl_mtables = NULL;
+}
+
+int
+lnet_ptl_setup(struct lnet_portal *ptl, int index)
+{
+	struct lnet_match_table	*mtable;
+	struct list_head		*mhash;
+	int			i;
+	int			j;
+
+	ptl->ptl_mtables = cfs_percpt_alloc(lnet_cpt_table(),
+					    sizeof(struct lnet_match_table));
+	if (ptl->ptl_mtables == NULL) {
+		CERROR("Failed to create match table for portal %d\n", index);
+		return -ENOMEM;
+	}
+
+	ptl->ptl_index = index;
+	INIT_LIST_HEAD(&ptl->ptl_msg_delayed);
+	INIT_LIST_HEAD(&ptl->ptl_msg_stealing);
+	spin_lock_init(&ptl->ptl_lock);
+	cfs_percpt_for_each(mtable, i, ptl->ptl_mtables) {
+		/* the extra entry is for MEs with ignore bits */
+		LIBCFS_CPT_ALLOC(mhash, lnet_cpt_table(), i,
+				 sizeof(*mhash) * (LNET_MT_HASH_SIZE + 1));
+		if (mhash == NULL) {
+			CERROR("Failed to create match hash for portal %d\n",
+			       index);
+			goto failed;
+		}
+
+		memset(&mtable->mt_exhausted[0], -1,
+		       sizeof(mtable->mt_exhausted[0]) *
+		       LNET_MT_EXHAUSTED_BMAP);
+		mtable->mt_mhash = mhash;
+		for (j = 0; j < LNET_MT_HASH_SIZE + 1; j++)
+			INIT_LIST_HEAD(&mhash[j]);
+
+		mtable->mt_portal = index;
+		mtable->mt_cpt = i;
+	}
+
+	return 0;
+ failed:
+	lnet_ptl_cleanup(ptl);
+	return -ENOMEM;
+}
+
+void
+lnet_portals_destroy(void)
+{
+	int	i;
+
+	if (the_lnet.ln_portals == NULL)
+		return;
+
+	for (i = 0; i < the_lnet.ln_nportals; i++)
+		lnet_ptl_cleanup(the_lnet.ln_portals[i]);
+
+	cfs_array_free(the_lnet.ln_portals);
+	the_lnet.ln_portals = NULL;
+}
+
+int
+lnet_portals_create(void)
+{
+	int	size;
+	int	i;
+
+	size = offsetof(struct lnet_portal, ptl_mt_maps[LNET_CPT_NUMBER]);
+
+	the_lnet.ln_nportals = MAX_PORTALS;
+	the_lnet.ln_portals = cfs_array_alloc(the_lnet.ln_nportals, size);
+	if (the_lnet.ln_portals == NULL) {
+		CERROR("Failed to allocate portals table\n");
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < the_lnet.ln_nportals; i++) {
+		if (lnet_ptl_setup(the_lnet.ln_portals[i], i)) {
+			lnet_portals_destroy();
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * Turn on the lazy portal attribute. Use with caution!
+ *
+ * This portal attribute only affects incoming PUT requests to the portal,
+ * and is off by default. By default, if there's no matching MD for an
+ * incoming PUT request, it is simply dropped. With the lazy attribute on,
+ * such requests are queued indefinitely until either a matching MD is
+ * posted to the portal or the lazy attribute is turned off.
+ *
+ * It would prevent dropped requests, however it should be regarded as the
+ * last line of defense - i.e. users must keep a close watch on active
+ * buffers on a lazy portal and once it becomes too low post more buffers as
+ * soon as possible. This is because delayed requests usually have detrimental
+ * effects on underlying network connections. A few delayed requests often
+ * suffice to bring an underlying connection to a complete halt, due to flow
+ * control mechanisms.
+ *
+ * There's also a DOS attack risk. If users don't post match-all MDs on a
+ * lazy portal, a malicious peer can easily stop a service by sending some
+ * PUT requests with match bits that won't match any MD. A routed server is
+ * especially vulnerable since the connections to its neighbor routers are
+ * shared among all clients.
+ *
+ * \param portal Index of the portal to enable the lazy attribute on.
+ *
+ * \retval 0       On success.
+ * \retval -EINVAL If \a portal is not a valid index.
+ */
+int
+LNetSetLazyPortal(int portal)
+{
+	struct lnet_portal *ptl;
+
+	if (portal < 0 || portal >= the_lnet.ln_nportals)
+		return -EINVAL;
+
+	CDEBUG(D_NET, "Setting portal %d lazy\n", portal);
+	ptl = the_lnet.ln_portals[portal];
+
+	lnet_res_lock(LNET_LOCK_EX);
+	lnet_ptl_lock(ptl);
+
+	lnet_ptl_setopt(ptl, LNET_PTL_LAZY);
+
+	lnet_ptl_unlock(ptl);
+	lnet_res_unlock(LNET_LOCK_EX);
+
+	return 0;
+}
+EXPORT_SYMBOL(LNetSetLazyPortal);
+
+/**
+ * Turn off the lazy portal attribute. Delayed requests on the portal,
+ * if any, will be all dropped when this function returns.
+ *
+ * \param portal Index of the portal to disable the lazy attribute on.
+ *
+ * \retval 0       On success.
+ * \retval -EINVAL If \a portal is not a valid index.
+ */
+int
+LNetClearLazyPortal(int portal)
+{
+	struct lnet_portal	*ptl;
+	LIST_HEAD		(zombies);
+
+	if (portal < 0 || portal >= the_lnet.ln_nportals)
+		return -EINVAL;
+
+	ptl = the_lnet.ln_portals[portal];
+
+	lnet_res_lock(LNET_LOCK_EX);
+	lnet_ptl_lock(ptl);
+
+	if (!lnet_ptl_is_lazy(ptl)) {
+		lnet_ptl_unlock(ptl);
+		lnet_res_unlock(LNET_LOCK_EX);
+		return 0;
+	}
+
+	if (the_lnet.ln_shutdown)
+		CWARN("Active lazy portal %d on exit\n", portal);
+	else
+		CDEBUG(D_NET, "clearing portal %d lazy\n", portal);
+
+	/* grab all the blocked messages atomically */
+	list_splice_init(&ptl->ptl_msg_delayed, &zombies);
+
+	lnet_ptl_unsetopt(ptl, LNET_PTL_LAZY);
+
+	lnet_ptl_unlock(ptl);
+	lnet_res_unlock(LNET_LOCK_EX);
+
+	lnet_drop_delayed_msg_list(&zombies, "Clearing lazy portal attr");
+
+	return 0;
+}
+EXPORT_SYMBOL(LNetClearLazyPortal);