// SPDX-License-Identifier: GPL-2.0

/*
 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2017, Intel Corporation.
 */

/*
 * This file is part of Lustre, http://www.lustre.org/
 *
 * Implementation of client-side PortalRPC interfaces
 */

#define DEBUG_SUBSYSTEM S_RPC

#include <linux/delay.h>
#include <linux/random.h>

#include <lnet/lib-lnet.h>
#include <obd_support.h>
#include <obd_class.h>
#include <lustre_lib.h>
#include <lustre_ha.h>
#include <lustre_import.h>
#include <lustre_req_layout.h>

#include "ptlrpc_internal.h"

static void ptlrpc_prep_bulk_page_pin(struct ptlrpc_bulk_desc *desc,
				      struct page *page, int pageoffset,
				      int len)
{
	__ptlrpc_prep_bulk_page(desc, page, pageoffset, len, 1);
}

static void ptlrpc_prep_bulk_page_nopin(struct ptlrpc_bulk_desc *desc,
					struct page *page, int pageoffset,
					int len)
{
	__ptlrpc_prep_bulk_page(desc, page, pageoffset, len, 0);
}

static void ptlrpc_release_bulk_page_pin(struct ptlrpc_bulk_desc *desc)
{
	int i;

	for (i = 0; i < desc->bd_iov_count ; i++)
		put_page(desc->bd_vec[i].bv_page);
}

static int ptlrpc_prep_bulk_frag_pages(struct ptlrpc_bulk_desc *desc,
				       void *frag, int len)
{
	unsigned int offset = (unsigned long)frag & ~PAGE_MASK;

	ENTRY;
	while (len > 0) {
		int page_len = min_t(unsigned int, PAGE_SIZE - offset,
				     len);
		struct page *p;

		if (!is_vmalloc_addr(frag))
			p = virt_to_page((unsigned long)frag);
		else
			p = vmalloc_to_page(frag);
		ptlrpc_prep_bulk_page_nopin(desc, p, offset, page_len);
		offset = 0;
		len -= page_len;
		frag += page_len;
	}

	RETURN(desc->bd_nob);
}

const struct ptlrpc_bulk_frag_ops ptlrpc_bulk_kiov_pin_ops = {
	.add_kiov_frag	= ptlrpc_prep_bulk_page_pin,
	.release_frags	= ptlrpc_release_bulk_page_pin,
};
EXPORT_SYMBOL(ptlrpc_bulk_kiov_pin_ops);

const struct ptlrpc_bulk_frag_ops ptlrpc_bulk_kiov_nopin_ops = {
	.add_kiov_frag	= ptlrpc_prep_bulk_page_nopin,
	.release_frags	= ptlrpc_release_bulk_noop,
	.add_iov_frag	= ptlrpc_prep_bulk_frag_pages,
};
EXPORT_SYMBOL(ptlrpc_bulk_kiov_nopin_ops);

static int ptlrpc_send_new_req(struct ptlrpc_request *req);
static int ptlrpc_unregister_reply(struct ptlrpc_request *request, int async);

/**
 * ptlrpc_init_client() - Initialize passed in client structure @cl
 * @req_portal: request portal(sending request) number
 * @rep_portal: reply portal(receiving request) number
 * @name: name of the client
 * @cl: struct pltrpc_client which is being initilize [out]
 */
void ptlrpc_init_client(int req_portal, int rep_portal, const char *name,
			struct ptlrpc_client *cl)
{
	cl->cli_request_portal = req_portal;
	cl->cli_reply_portal   = rep_portal;
	cl->cli_name           = name;
}
EXPORT_SYMBOL(ptlrpc_init_client);

/**
 * ptlrpc_uuid_to_connection() - Return PortalRPC connection for remote uuid
 * @uuid
 * @uuid: remote @uuid to connect
 * @refnet: reference network
 *
 * Return struct ptlrpc_connection on success and error pointer on failure
 */
struct ptlrpc_connection *ptlrpc_uuid_to_connection(struct obd_uuid *uuid,
						    u32 refnet)
{
	struct ptlrpc_connection *c;
	struct lnet_nid self;
	struct lnet_processid peer;
	int err;

	/*
	 * ptlrpc_uuid_to_peer() initializes its 2nd parameter
	 * before accessing its values.
	 */
	err = ptlrpc_uuid_to_peer(uuid, &peer, &self, refnet);
	if (err != 0) {
		CNETERR("cannot find peer %s!\n", uuid->uuid);
		return ERR_PTR(err);
	}

	c = ptlrpc_connection_get(&peer, &self, uuid);

	CDEBUG(D_INFO, "%s -> %p\n", uuid->uuid, c);

	return c ? c : ERR_PTR(-ENOENT);
}

/**
 * ptlrpc_new_bulk() - Allocate and initialize new bulk descriptor on the sender
 * @nfrags: (nfrags * pages) done during this bulk transfer
 * @max_brw: maximum read/write which can be done during this bulk transfer
 * @type: type of bulk transfer (PTLRPC_BULK_*)
 * @portal: Endpoint to do bulk transfer
 * @ops: callbacks function for this bulk routine
 *
 * Returns pointer to the descriptor or NULL on error.
 */
struct ptlrpc_bulk_desc *ptlrpc_new_bulk(unsigned int nfrags,
					 unsigned int max_brw,
					 enum ptlrpc_bulk_op_type type,
					 unsigned int portal,
					 const struct ptlrpc_bulk_frag_ops *ops)
{
	struct ptlrpc_bulk_desc *desc;
	int i;

	LASSERT(ops->add_kiov_frag != NULL);

	if (max_brw > PTLRPC_BULK_OPS_COUNT)
		RETURN(NULL);

	if (nfrags > LNET_MAX_IOV * max_brw)
		RETURN(NULL);

	OBD_ALLOC_PTR(desc);
	if (!desc)
		return NULL;

	OBD_ALLOC_LARGE(desc->bd_vec,
			nfrags * sizeof(*desc->bd_vec));
	if (!desc->bd_vec)
		goto out;

	spin_lock_init(&desc->bd_lock);
	init_waitqueue_head(&desc->bd_waitq);
	desc->bd_max_iov = nfrags;
	desc->bd_iov_count = 0;
	desc->bd_portal = portal;
	desc->bd_type = type;
	desc->bd_md_count = 0;
	desc->bd_iop_len = 0;
	desc->bd_frag_ops = ops;
	LASSERT(max_brw > 0);
	desc->bd_md_max_brw = min(max_brw, PTLRPC_BULK_OPS_COUNT);
	/*
	 * PTLRPC_BULK_OPS_COUNT is the compile-time transfer limit for this
	 * node. Negotiated ocd_brw_size will always be <= this number.
	 */
	for (i = 0; i < PTLRPC_BULK_OPS_LIMIT; i++)
		LNetInvalidateMDHandle(&desc->bd_mds[i]);

	return desc;
out:
	OBD_FREE_PTR(desc);
	return NULL;
}

/*
 * ptlrpc_prep_bulk_imp() - Prepare bulk descriptor(wrapper to @ptlrpc_new_bulk)
 * @req: outgoint request
 * @nfrags: (nfrags * pages) done during this bulk transfer
 * @max_brw: maximum read/write which can be done during this bulk transfer
 * @type: type of bulk transfer (PTLRPC_BULK_*)
 * @portal: Endpoint to do bulk transfer
 * @ops: callbacks function for this bulk routine
 *
 * This is used on client side.
 *
 * Returns pointer to newly allocatrd initialized bulk descriptor or NULL on
 * error.
 */
struct ptlrpc_bulk_desc *ptlrpc_prep_bulk_imp(struct ptlrpc_request *req,
					      unsigned int nfrags,
					      unsigned int max_brw,
					      unsigned int type,
					      unsigned int portal,
					      const struct ptlrpc_bulk_frag_ops
						*ops)
{
	struct obd_import *imp = req->rq_import;
	struct ptlrpc_bulk_desc *desc;

	ENTRY;
	LASSERT(ptlrpc_is_bulk_op_passive(type));

	desc = ptlrpc_new_bulk(nfrags, max_brw, type, portal, ops);
	if (!desc)
		RETURN(NULL);

	desc->bd_import = class_import_get(imp);
	desc->bd_req = req;

	desc->bd_cbid.cbid_fn  = client_bulk_callback;
	desc->bd_cbid.cbid_arg = desc;

	/* This makes req own desc, and free it when she frees herself */
	req->rq_bulk = desc;

	return desc;
}
EXPORT_SYMBOL(ptlrpc_prep_bulk_imp);

#define IOP_MASK	(~(PTLRPC_BULK_INTEROP_PAGE_SIZE - 1))
#define IOP_LEN(len)	((len + PTLRPC_BULK_INTEROP_PAGE_SIZE - 1) & IOP_MASK)

static void __ptlrpc_add_bulk_chunk(struct ptlrpc_bulk_desc *desc,
			     struct page *page, int pageoffset, int len,
			     int pin)
{
	struct bio_vec *kiov;

	kiov = &desc->bd_vec[desc->bd_iov_count];

	desc->bd_iop_len += IOP_LEN(len);
	desc->bd_nob += len;

	if (pin)
		get_page(page);

	kiov->bv_page = page;
	kiov->bv_offset = pageoffset;
	kiov->bv_len = len;

	desc->bd_iov_count++;
	LASSERT(desc->bd_iov_count <= desc->bd_max_iov);
}

/* add one page to desc->bd_vec bio_vec array and advance */
void __ptlrpc_prep_bulk_page(struct ptlrpc_bulk_desc *desc,
			     struct page *page, int pageoffset, int len,
			     int pin)
{
	LASSERT(page != NULL);
	LASSERT(pageoffset >= 0);
	LASSERT(len > 0);
	LASSERT(pageoffset + len <= PAGE_SIZE);

restart:
	if (((desc->bd_iov_count % LNET_MAX_IOV) == 0) ||
	    ((desc->bd_iop_len + PTLRPC_BULK_INTEROP_PAGE_SIZE) > LNET_MTU)) {
		/* no free for align chunk */
		desc->bd_mds_off[desc->bd_md_count] = desc->bd_iov_count;
		desc->bd_md_count++;
		desc->bd_iop_len = 0;
		LASSERT(desc->bd_md_count <= PTLRPC_BULK_OPS_LIMIT);
		if (desc->bd_md_count > desc->bd_md_max_brw &&
		   (desc->bd_md_max_brw << 1) <= PTLRPC_BULK_OPS_COUNT)
			desc->bd_md_max_brw = (desc->bd_md_max_brw << 1);
	} else if ((desc->bd_iop_len + len) > LNET_MTU) {
		/* can't fit full chunk but should have some aligned chunks */
		/* lets find how much align chunks can fit in current md */
		unsigned int ch = LNET_MTU - desc->bd_iop_len;
		unsigned int sz = ch & ~(PTLRPC_BULK_INTEROP_PAGE_SIZE - 1);

		__ptlrpc_add_bulk_chunk(desc, page, pageoffset, sz, pin);

		/* create a new, different kiov chunk mapped to the same page */
		pageoffset += sz;
		len -= sz;
		goto restart;
	}
	__ptlrpc_add_bulk_chunk(desc, page, pageoffset, len, pin);
}
EXPORT_SYMBOL(__ptlrpc_prep_bulk_page);

void ptlrpc_free_bulk(struct ptlrpc_bulk_desc *desc)
{
	ENTRY;

	if (!desc)
		return;

	LASSERT(desc->bd_iov_count != LI_POISON); /* not freed already */
	LASSERT(desc->bd_refs == 0);         /* network hands off */
	LASSERT((desc->bd_export != NULL) ^ (desc->bd_import != NULL));
	LASSERT(desc->bd_frag_ops != NULL);

	obd_pool_put_desc_pages(desc);

	if (desc->bd_is_srv)
		class_export_put(desc->bd_export);
	else
		class_import_put(desc->bd_import);

	if (desc->bd_frag_ops->release_frags != NULL)
		desc->bd_frag_ops->release_frags(desc);

	OBD_FREE_LARGE(desc->bd_vec,
		       desc->bd_max_iov * sizeof(*desc->bd_vec));
	OBD_FREE_PTR(desc);
	EXIT;
}
EXPORT_SYMBOL(ptlrpc_free_bulk);

/**
 * ptlrpc_at_set_req_timeout() - Set server timelimit for this req
 * @req: Request for which timeout is being set
 *
 * How long are we willing to wait for reply before timing out this request.
 */
void ptlrpc_at_set_req_timeout(struct ptlrpc_request *req)
{
	struct obd_device *obd;

	LASSERT(req->rq_import);
	obd = req->rq_import->imp_obd;

	if (obd_at_off(obd)) {
		/* non-AT settings */
		/**
		 * \a imp_server_timeout means this is reverse import and
		 * we send (currently only) ASTs to the client and cannot afford
		 * to wait too long for the reply, otherwise the other client
		 * (because of which we are sending this request) would
		 * timeout waiting for us
		 */
		req->rq_timeout = req->rq_import->imp_server_timeout ?
				  obd_timeout / 2 : obd_timeout;
	} else {
		struct imp_at *at = &req->rq_import->imp_at;
		timeout_t serv_est;
		int idx;

		idx = import_at_get_index(req->rq_import,
					  req->rq_request_portal);
		serv_est = obd_at_get(obd, &at->iat_service_estimate[idx]);
		/*
		 * Currently a 32 bit value is sent over the
		 * wire for rq_timeout so please don't change this
		 * to time64_t. The work for LU-1158 will in time
		 * replace rq_timeout with a 64 bit nanosecond value
		 */
		req->rq_timeout = at_est2timeout(serv_est);
	}
	/*
	 * We could get even fancier here, using history to predict increased
	 * loading...
	 *
	 * Let the server know what this RPC timeout is by putting it in the
	 * reqmsg
	 */
	lustre_msg_set_timeout(req->rq_reqmsg, req->rq_timeout);
}
EXPORT_SYMBOL(ptlrpc_at_set_req_timeout);

/* Adjust max service estimate based on server value */
static void ptlrpc_at_adj_service(struct ptlrpc_request *req,
				  timeout_t serv_est)
{
	int idx;
	timeout_t oldse;
	struct imp_at *at;
	struct obd_device *obd;

	LASSERT(req->rq_import);
	obd = req->rq_import->imp_obd;
	at = &req->rq_import->imp_at;

	idx = import_at_get_index(req->rq_import, req->rq_request_portal);
	/*
	 * max service estimates are tracked on the server side,
	 * so just keep minimal history here
	 */
	oldse = obd_at_measure(obd, &at->iat_service_estimate[idx], serv_est);
	if (oldse != 0) {
		unsigned int at_est = obd_at_get(obd,
						&at->iat_service_estimate[idx]);
		CDEBUG(D_ADAPTTO,
		       "The RPC service estimate for %s ptl %d has changed from %d to %d\n",
		       req->rq_import->imp_obd->obd_name,
		       req->rq_request_portal,
		       oldse, at_est);
	}
}

/**
 * ptlrpc_at_get_net_latency() - Returns Expected network latency per remote
 * node (secs)
 * @req: ptlrpc request
 *
 * Return:
 * * %0 if AT(Adaptive Timeout) is off
 * * %>0 (iat_net_latency) latency per node
 */
int ptlrpc_at_get_net_latency(struct ptlrpc_request *req)
{
	struct obd_device *obd = req->rq_import->imp_obd;

	return obd_at_off(obd) ?
	       0 : obd_at_get(obd, &req->rq_import->imp_at.iat_net_latency);
}

/* Adjust expected network latency */
void ptlrpc_at_adj_net_latency(struct ptlrpc_request *req,
			       timeout_t service_timeout)
{
	time64_t now = ktime_get_real_seconds();
	struct imp_at *at;
	timeout_t oldnl;
	timeout_t nl;
	struct obd_device *obd;

	LASSERT(req->rq_import);
	obd = req->rq_import->imp_obd;

	if (service_timeout > now - req->rq_sent + 3) {
		/*
		 * b=16408, however, this can also happen if early reply
		 * is lost and client RPC is expired and resent, early reply
		 * or reply of original RPC can still be fit in reply buffer
		 * of resent RPC, now client is measuring time from the
		 * resent time, but server sent back service time of original
		 * RPC.
		 */
		CDEBUG_LIMIT((lustre_msg_get_flags(req->rq_reqmsg) &
			      MSG_RESENT) ?  D_ADAPTTO : D_WARNING,
			     "Reported service time %u > total measured time %lld\n",
			     service_timeout, now - req->rq_sent);
		return;
	}

	/* Network latency is total time less server processing time,
	 * st rounding
	 */
	nl = max_t(timeout_t, now - req->rq_sent - service_timeout, 0) + 1;
	at = &req->rq_import->imp_at;

	oldnl = obd_at_measure(obd, &at->iat_net_latency, nl);
	if (oldnl != 0) {
		timeout_t timeout = obd_at_get(obd, &at->iat_net_latency);

		CDEBUG(D_ADAPTTO,
		       "The network latency for %s (nid %s) has changed from %d to %d\n",
		       req->rq_import->imp_obd->obd_name,
		       libcfs_nidstr(&req->rq_import->imp_connection->c_peer.nid),
		       oldnl, timeout);
	}
}

static int unpack_reply(struct ptlrpc_request *req)
{
	int rc;

	if (SPTLRPC_FLVR_POLICY(req->rq_flvr.sf_rpc) != SPTLRPC_POLICY_NULL) {
		rc = ptlrpc_unpack_rep_msg(req, req->rq_replen);
		if (rc) {
			DEBUG_REQ(D_ERROR, req, "unpack_rep failed: rc = %d",
				  rc);
			return -EPROTO;
		}
	}

	rc = lustre_unpack_rep_ptlrpc_body(req, MSG_PTLRPC_BODY_OFF);
	if (rc) {
		DEBUG_REQ(D_ERROR, req, "unpack ptlrpc body failed: rc = %d",
			  rc);
		return -EPROTO;
	}
	return 0;
}

/*
 * Handle an early reply message, called with the rq_lock held.
 * If anything goes wrong just ignore it - same as if it never happened
 */
static int ptlrpc_at_recv_early_reply(struct ptlrpc_request *req)
__must_hold(&req->rq_lock)
{
	struct ptlrpc_request *early_req;
	timeout_t service_timeout;
	time64_t olddl;
	int rc;

	ENTRY;
	req->rq_early = 0;
	spin_unlock(&req->rq_lock);

	rc = sptlrpc_cli_unwrap_early_reply(req, &early_req);
	if (rc) {
		spin_lock(&req->rq_lock);
		RETURN(rc);
	}

	rc = unpack_reply(early_req);
	if (rc != 0) {
		sptlrpc_cli_finish_early_reply(early_req);
		spin_lock(&req->rq_lock);
		RETURN(rc);
	}

	/*
	 * Use new timeout value just to adjust the local value for this
	 * request, don't include it into at_history. It is unclear yet why
	 * service time increased and should it be counted or skipped, e.g.
	 * that can be recovery case or some error or server, the real reply
	 * will add all new data if it is worth to add.
	 */
	req->rq_timeout = lustre_msg_get_timeout(early_req->rq_repmsg);
	lustre_msg_set_timeout(req->rq_reqmsg, req->rq_timeout);

	/* Network latency can be adjusted, it is pure network delays */
	service_timeout = lustre_msg_get_service_timeout(early_req->rq_repmsg);
	ptlrpc_at_adj_net_latency(req, service_timeout);

	sptlrpc_cli_finish_early_reply(early_req);

	spin_lock(&req->rq_lock);
	olddl = req->rq_deadline;
	/*
	 * server assumes it now has rq_timeout from when the request
	 * arrived, so the client should give it at least that long.
	 * since we don't know the arrival time we'll use the original
	 * sent time
	 */
	req->rq_deadline = req->rq_sent + req->rq_timeout +
			   ptlrpc_at_get_net_latency(req);

	/* The below message is checked in replay-single.sh test_65{a,b} */
	/* The below message is checked in sanity-{gss,krb5} test_8 */
	DEBUG_REQ(D_ADAPTTO, req,
		  "Early reply #%d, new deadline in %llds (%llds)",
		  req->rq_early_count,
		  req->rq_deadline - ktime_get_real_seconds(),
		  req->rq_deadline - olddl);

	RETURN(rc);
}

static struct kmem_cache *request_cache;

int ptlrpc_request_cache_init(void)
{
	request_cache = kmem_cache_create("ptlrpc_cache",
					  sizeof(struct ptlrpc_request),
					  0, SLAB_HWCACHE_ALIGN, NULL);
	return request_cache ? 0 : -ENOMEM;
}

void ptlrpc_request_cache_fini(void)
{
	kmem_cache_destroy(request_cache);
}

struct ptlrpc_request *ptlrpc_request_cache_alloc(gfp_t flags)
{
	struct ptlrpc_request *req;

	OBD_SLAB_ALLOC_PTR_GFP(req, request_cache, flags);
	return req;
}

void ptlrpc_request_cache_free(struct ptlrpc_request *req)
{
	OBD_SLAB_FREE_PTR(req, request_cache);
}

/**
 * ptlrpc_free_rq_pool() - Frees all requests from the pool.
 * @pool: struct ptlrpc_request_pool (empty preallocated requests)
 *
 * Also, Wind down request pool @pool
 */
void ptlrpc_free_rq_pool(struct ptlrpc_request_pool *pool)
{
	struct ptlrpc_request *req;

	LASSERT(pool != NULL);

	spin_lock(&pool->prp_lock);
	while ((req = list_first_entry_or_null(&pool->prp_req_list,
					       struct ptlrpc_request,
					       rq_list))) {
		list_del(&req->rq_list);
		LASSERT(req->rq_reqbuf);
		LASSERT(req->rq_reqbuf_len == pool->prp_rq_size);
		OBD_FREE_LARGE(req->rq_reqbuf, pool->prp_rq_size);
		ptlrpc_request_cache_free(req);
	}
	spin_unlock(&pool->prp_lock);
	OBD_FREE(pool, sizeof(*pool));
}
EXPORT_SYMBOL(ptlrpc_free_rq_pool);

/**
 * ptlrpc_add_rqs_to_pool() - Allocates, initializes & adds @num_rq requests
 * to the pool @pool
 * @pool: pool where request should be added
 * @num_rq: count of request to add to @pool
 *
 * Return total number of requests successfully added to the pool.
 */
int ptlrpc_add_rqs_to_pool(struct ptlrpc_request_pool *pool, int num_rq)
{
	int i;
	int size = 1;

	while (size < pool->prp_rq_size)
		size <<= 1;

	LASSERTF(list_empty(&pool->prp_req_list) ||
		 size == pool->prp_rq_size,
		 "Trying to change pool size with nonempty pool from %d to %d bytes\n",
		 pool->prp_rq_size, size);

	pool->prp_rq_size = size;
	for (i = 0; i < num_rq; i++) {
		struct ptlrpc_request *req;
		struct lustre_msg *msg;

		req = ptlrpc_request_cache_alloc(GFP_NOFS);
		if (!req)
			return i;
		OBD_ALLOC_LARGE(msg, size);
		if (!msg) {
			ptlrpc_request_cache_free(req);
			return i;
		}
		req->rq_reqbuf = msg;
		req->rq_reqbuf_len = size;
		req->rq_pool = pool;
		spin_lock(&pool->prp_lock);
		list_add_tail(&req->rq_list, &pool->prp_req_list);
		spin_unlock(&pool->prp_lock);
	}
	return num_rq;
}
EXPORT_SYMBOL(ptlrpc_add_rqs_to_pool);

/**
 * ptlrpc_init_rq_pool() - Create and initialize new request pool with given
 * attributes
 * @num_rq: initial number of requests to create for the pool
 * @msgsize: maximum message size possible for requests in thid pool
 * @populate_pool: function to be called when more requests need to be added
 * to the pool
 *
 * Returns pointer to newly created pool or NULL on error.
 */
struct ptlrpc_request_pool *
ptlrpc_init_rq_pool(int num_rq, int msgsize,
		    int (*populate_pool)(struct ptlrpc_request_pool *, int))
{
	struct ptlrpc_request_pool *pool;

	OBD_ALLOC_PTR(pool);
	if (!pool)
		return NULL;

	/*
	 * Request next power of two for the allocation, because internally
	 * kernel would do exactly this
	 */
	spin_lock_init(&pool->prp_lock);
	INIT_LIST_HEAD(&pool->prp_req_list);
	pool->prp_rq_size = msgsize + SPTLRPC_MAX_PAYLOAD;
	pool->prp_populate = populate_pool;

	populate_pool(pool, num_rq);

	return pool;
}
EXPORT_SYMBOL(ptlrpc_init_rq_pool);

/*
 * Fetches one request from pool @pool.
 * Called from ptlrpc_request_alloc_internal
 */
static struct ptlrpc_request *
ptlrpc_prep_req_from_pool(struct ptlrpc_request_pool *pool)
{
	struct ptlrpc_request *request;
	struct lustre_msg *reqbuf;

	if (!pool)
		return NULL;

	spin_lock(&pool->prp_lock);

	/*
	 * See if we have anything in a pool, and bail out if nothing,
	 * in writeout path, where this matters, this is safe to do, because
	 * nothing is lost in this case, and when some in-flight requests
	 * complete, this code will be called again.
	 */
	if (unlikely(list_empty(&pool->prp_req_list))) {
		spin_unlock(&pool->prp_lock);
		return NULL;
	}

	request = list_first_entry(&pool->prp_req_list, struct ptlrpc_request,
				   rq_list);
	list_del_init(&request->rq_list);
	spin_unlock(&pool->prp_lock);

	LASSERT(request->rq_reqbuf);
	LASSERT(request->rq_pool);

	reqbuf = request->rq_reqbuf;
	memset(request, 0, sizeof(*request));
	request->rq_reqbuf = reqbuf;
	request->rq_reqbuf_len = pool->prp_rq_size;
	request->rq_pool = pool;

	return request;
}

/*
 * Returns freed @request to pool.
 */
static void __ptlrpc_free_req_to_pool(struct ptlrpc_request *request)
{
	struct ptlrpc_request_pool *pool = request->rq_pool;

	spin_lock(&pool->prp_lock);
	LASSERT(list_empty(&request->rq_list));
	LASSERT(!request->rq_receiving_reply);
	list_add_tail(&request->rq_list, &pool->prp_req_list);
	spin_unlock(&pool->prp_lock);
}

void ptlrpc_add_unreplied(struct ptlrpc_request *req)
{
	struct obd_import *imp = req->rq_import;
	struct ptlrpc_request *iter;

	assert_spin_locked(&imp->imp_lock);
	LASSERT(list_empty(&req->rq_unreplied_list));

	/* unreplied list is sorted by xid in ascending order */
	list_for_each_entry_reverse(iter, &imp->imp_unreplied_list,
				    rq_unreplied_list) {
		LASSERT(req->rq_xid != iter->rq_xid);
		if (req->rq_xid < iter->rq_xid)
			continue;
		list_add(&req->rq_unreplied_list, &iter->rq_unreplied_list);
		return;
	}
	list_add(&req->rq_unreplied_list, &imp->imp_unreplied_list);
}

void ptlrpc_assign_next_xid_nolock(struct ptlrpc_request *req)
{
	req->rq_xid = ptlrpc_next_xid();
	ptlrpc_add_unreplied(req);
}

static inline void ptlrpc_assign_next_xid(struct ptlrpc_request *req)
{
	spin_lock(&req->rq_import->imp_lock);
	ptlrpc_assign_next_xid_nolock(req);
	spin_unlock(&req->rq_import->imp_lock);
}

static atomic64_t ptlrpc_last_xid;

static void ptlrpc_reassign_next_xid(struct ptlrpc_request *req)
{
	spin_lock(&req->rq_import->imp_lock);
	list_del_init(&req->rq_unreplied_list);
	ptlrpc_assign_next_xid_nolock(req);
	spin_unlock(&req->rq_import->imp_lock);
	DEBUG_REQ(D_RPCTRACE, req, "reassign xid");
}

void ptlrpc_get_mod_rpc_slot(struct ptlrpc_request *req)
{
	struct client_obd *cli = &req->rq_import->imp_obd->u.cli;
	__u32 opc;
	__u16 tag;

	opc = lustre_msg_get_opc(req->rq_reqmsg);
	tag = obd_get_mod_rpc_slot(cli, opc);
	lustre_msg_set_tag(req->rq_reqmsg, tag);
	ptlrpc_reassign_next_xid(req);
}
EXPORT_SYMBOL(ptlrpc_get_mod_rpc_slot);

void ptlrpc_put_mod_rpc_slot(struct ptlrpc_request *req)
{
	__u16 tag = lustre_msg_get_tag(req->rq_reqmsg);

	if (tag != 0) {
		struct client_obd *cli = &req->rq_import->imp_obd->u.cli;
		__u32 opc = lustre_msg_get_opc(req->rq_reqmsg);

		obd_put_mod_rpc_slot(cli, opc, tag);
	}
}
EXPORT_SYMBOL(ptlrpc_put_mod_rpc_slot);

int ptlrpc_request_bufs_pack(struct ptlrpc_request *request,
			     __u32 version, int opcode, char **bufs,
			     struct ptlrpc_cli_ctx *ctx)
{
	int count;
	struct obd_import *imp;
	__u32 *lengths;
	int rc;

	ENTRY;

	count = req_capsule_filled_sizes(&request->rq_pill, RCL_CLIENT);
	imp = request->rq_import;
	lengths = request->rq_pill.rc_area[RCL_CLIENT];

	if (ctx) {
		request->rq_cli_ctx = sptlrpc_cli_ctx_get(ctx);
	} else {
		rc = sptlrpc_req_get_ctx(request);
		if (rc)
			GOTO(out_free, rc);
	}
	sptlrpc_req_set_flavor(request, opcode);

	rc = lustre_pack_request(request, imp->imp_msg_magic, count,
				 lengths, bufs);
	if (rc)
		GOTO(out_ctx, rc);

	lustre_msg_add_version(request->rq_reqmsg, version);
	request->rq_send_state = LUSTRE_IMP_FULL;
	request->rq_type = PTL_RPC_MSG_REQUEST;

	request->rq_req_cbid.cbid_fn  = request_out_callback;
	request->rq_req_cbid.cbid_arg = request;

	request->rq_reply_cbid.cbid_fn  = reply_in_callback;
	request->rq_reply_cbid.cbid_arg = request;

	request->rq_reply_deadline = 0;
	request->rq_bulk_deadline = 0;
	request->rq_req_deadline = 0;
	request->rq_phase = RQ_PHASE_NEW;
	request->rq_next_phase = RQ_PHASE_UNDEFINED;

	request->rq_request_portal = imp->imp_client->cli_request_portal;
	request->rq_reply_portal = imp->imp_client->cli_reply_portal;

	ptlrpc_at_set_req_timeout(request);

	lustre_msg_set_opc(request->rq_reqmsg, opcode);

	/* Let's setup deadline for req/reply/bulk unlink for opcode. */
	if (cfs_fail_val == opcode) {
		time64_t *fail_t = NULL, *fail2_t = NULL;

		if (CFS_FAIL_CHECK(OBD_FAIL_PTLRPC_LONG_BULK_UNLINK)) {
			fail_t = &request->rq_bulk_deadline;
		} else if (CFS_FAIL_CHECK(OBD_FAIL_PTLRPC_LONG_REPL_UNLINK)) {
			fail_t = &request->rq_reply_deadline;
		} else if (CFS_FAIL_CHECK(OBD_FAIL_PTLRPC_LONG_REQ_UNLINK)) {
			fail_t = &request->rq_req_deadline;
		} else if (CFS_FAIL_CHECK(OBD_FAIL_PTLRPC_LONG_BOTH_UNLINK)) {
			fail_t = &request->rq_reply_deadline;
			fail2_t = &request->rq_bulk_deadline;
		} else if (CFS_FAIL_CHECK(OBD_FAIL_PTLRPC_ROUND_XID)) {
			time64_t now = ktime_get_real_seconds();
			u64 xid = ((u64)now >> 4) << 24;

			atomic64_set(&ptlrpc_last_xid, xid);
		}

		if (fail_t) {
			*fail_t = ktime_get_real_seconds() +
				  PTLRPC_REQ_LONG_UNLINK;

			if (fail2_t)
				*fail2_t = ktime_get_real_seconds() +
					   PTLRPC_REQ_LONG_UNLINK;

			/*
			 * The RPC is infected, let the test to change the
			 * fail_loc
			 */
			msleep(4 * MSEC_PER_SEC);
		}
	}
	ptlrpc_assign_next_xid(request);

	RETURN(0);

out_ctx:
	LASSERT(!request->rq_pool);
	sptlrpc_cli_ctx_put(request->rq_cli_ctx, 1);
out_free:
	atomic_dec(&imp->imp_reqs);
	class_import_put(imp);

	return rc;
}
EXPORT_SYMBOL(ptlrpc_request_bufs_pack);

/**
 * ptlrpc_request_pack() - Pack request buffers for network transfer, performing
 * necessary encryption steps if necessary.
 * @request: request that needs to be packed
 * @version: protocol version
 * @opcode: operation type
 *
 * Return:
 * * %0 on success
 * * %negative value on failure
 */
int ptlrpc_request_pack(struct ptlrpc_request *request,
			__u32 version, int opcode)
{
	return ptlrpc_request_bufs_pack(request, version, opcode, NULL, NULL);
}
EXPORT_SYMBOL(ptlrpc_request_pack);

/*
 * __ptlrpc_request_alloc() - Helper function to allocate new request on import.
 * @imp: request allocated for this import
 * @pool: struct ptlrpc_request_pool (empty preallocated requests). NULL if no
 *
 * Returns allocated request structure with import field filled or
 * NULL on error.
 */
static inline
struct ptlrpc_request *__ptlrpc_request_alloc(struct obd_import *imp,
					      struct ptlrpc_request_pool *pool)
{
	struct ptlrpc_request *request = NULL;

	request = ptlrpc_request_cache_alloc(GFP_NOFS);

	if (!request && pool)
		request = ptlrpc_prep_req_from_pool(pool);

	if (request) {
		ptlrpc_cli_req_init(request);

		LASSERTF((unsigned long)imp > 0x1000, "%px\n", imp);
		LASSERT(imp != LP_POISON);
		LASSERTF((unsigned long)imp->imp_client > 0x1000, "%px\n",
			 imp->imp_client);
		LASSERT(imp->imp_client != LP_POISON);

		request->rq_import = class_import_get(imp);
		atomic_inc(&imp->imp_reqs);
	} else {
		CERROR("request allocation out of memory\n");
	}

	return request;
}

static int ptlrpc_reconnect_if_idle(struct obd_import *imp)
{
	int rc;

	/*
	 * initiate connection if needed when the import has been
	 * referenced by the new request to avoid races with disconnect.
	 * serialize this check against conditional state=IDLE
	 * in ptlrpc_disconnect_idle_interpret()
	 */
	spin_lock(&imp->imp_lock);
	if (imp->imp_state == LUSTRE_IMP_IDLE) {
		imp->imp_generation++;
		imp->imp_initiated_at = imp->imp_generation;
		imp->imp_state = LUSTRE_IMP_NEW;

		/* connect_import_locked releases imp_lock */
		rc = ptlrpc_connect_import_locked(imp);
		if (rc)
			return rc;
		ptlrpc_pinger_add_import(imp);
	} else {
		spin_unlock(&imp->imp_lock);
	}
	return 0;
}

/**
 * ptlrpc_request_alloc_internal() - Helper function for creating a request.
 * @imp: request allocated for this import
 * @pool: struct ptlrpc_request_pool (empty preallocated requests). NULL if no
 * pool should be used
 * @format: pointer to struct req_format
 *
 * Calls __ptlrpc_request_alloc to allocate new request sturcture and inits
 * buffer structures according to capsule template @format
 *
 * Returns allocated request structure pointer or NULL on error.
 */
static struct ptlrpc_request *
ptlrpc_request_alloc_internal(struct obd_import *imp,
			      struct ptlrpc_request_pool *pool,
			      const struct req_format *format)
{
	struct ptlrpc_request *request;

	request = __ptlrpc_request_alloc(imp, pool);
	if (!request)
		return NULL;

	/* don't make expensive check for idling connection
	 * if it's already connected */
	if (unlikely(imp->imp_state != LUSTRE_IMP_FULL)) {
		if (ptlrpc_reconnect_if_idle(imp) < 0) {
			atomic_dec(&imp->imp_reqs);
			ptlrpc_request_free(request);
			return NULL;
		}
	}

	req_capsule_init(&request->rq_pill, request, RCL_CLIENT);
	req_capsule_set(&request->rq_pill, format);
	return request;
}

/**
 * ptlrpc_request_alloc() - Allocate new request structure for import @imp
 * @imp: pointer to struct obd_import
 * @format: pointer to struct req_format
 *
 * Also, initialize its buffer structure according to capsule template @format.
 *
 * Returns allocated request on success, and -errno on failure.
 */
struct ptlrpc_request *ptlrpc_request_alloc(struct obd_import *imp,
					    const struct req_format *format)
{
	return ptlrpc_request_alloc_internal(imp, NULL, format);
}
EXPORT_SYMBOL(ptlrpc_request_alloc);

/**
 * ptlrpc_request_alloc_pool() - Allocate new request struct for import
 * @imp: request allocated for this import
 * @pool: struct ptlrpc_request_pool (empty preallocated requests). NULL if no
 * pool should be used
 * @format: pointer to struct req_format
 *
 * Allocate new request structure for import @imp from pool @pool and
 * initialize its buffer structure according to capsule template @format.
 *
 * Returns allocated request structure pointer or NULL on error.
 */
struct ptlrpc_request *
ptlrpc_request_alloc_pool(struct obd_import *imp,
			  struct ptlrpc_request_pool *pool,
			  const struct req_format *format)
{
	return ptlrpc_request_alloc_internal(imp, pool, format);
}
EXPORT_SYMBOL(ptlrpc_request_alloc_pool);

/**
 * ptlrpc_request_free() - Free mem of the request struct
 * @request: Lustre request(RPC)
 *
 * For requests not from pool, free memory of the request structure. For
 * requests obtained from a pool earlier, return request back to pool.
 */
void ptlrpc_request_free(struct ptlrpc_request *request)
{
	if (request->rq_pool)
		__ptlrpc_free_req_to_pool(request);
	else
		ptlrpc_request_cache_free(request);
}
EXPORT_SYMBOL(ptlrpc_request_free);

/**
 * ptlrpc_request_alloc_pack() - Allocate new rquest for operation
 * @imp: request to allocate for this import
 * @format: pointer to struct req_format
 * @version: protocol version
 * @opcode: operation type
 *
 * Allocate new request for operation @opcode and immediatelly pack it for
 * network transfer. Only used for simple requests like OBD_PING where the only
 * important part of the request is operation itself.
 *
 * Returns allocated request on success, and -errno on failure.
 */
struct ptlrpc_request *ptlrpc_request_alloc_pack(struct obd_import *imp,
						 const struct req_format *format,
						 __u32 version, int opcode)
{
	struct ptlrpc_request *req;
	int rc;

	req = ptlrpc_request_alloc(imp, format);
	if (!req)
		return ERR_PTR(-ENOMEM);

	rc = ptlrpc_request_pack(req, version, opcode);
	if (rc) {
		ptlrpc_request_free(req);
		return ERR_PTR(rc);
	}

	return req;
}
EXPORT_SYMBOL(ptlrpc_request_alloc_pack);

/**
 * ptlrpc_prep_set() - Allocate and initialize new request structure
 *
 * Allocate and initialize new request set structure on the current CPT.
 * Returns a pointer to the newly allocated set structure or NULL on error.
 */
struct ptlrpc_request_set *ptlrpc_prep_set(void)
{
	struct ptlrpc_request_set *set;
	int cpt;

	ENTRY;
	cpt = cfs_cpt_current(cfs_cpt_tab, 0);
	OBD_CPT_ALLOC(set, cfs_cpt_tab, cpt, sizeof(*set));
	if (!set)
		RETURN(NULL);
	kref_init(&set->set_refcount);
	INIT_LIST_HEAD(&set->set_requests);
	init_waitqueue_head(&set->set_waitq);
	atomic_set(&set->set_new_count, 0);
	atomic_set(&set->set_remaining, 0);
	spin_lock_init(&set->set_new_req_lock);
	INIT_LIST_HEAD(&set->set_new_requests);
	set->set_max_inflight = UINT_MAX;
	set->set_producer     = NULL;
	set->set_producer_arg = NULL;
	set->set_rc           = 0;

	RETURN(set);
}
EXPORT_SYMBOL(ptlrpc_prep_set);

/**
 * ptlrpc_prep_fcset() - Allocate and initialize new request set
 * @max: max in-flight request
 * @func: Function to add more request
 * @arg: Additional arguments
 *
 * Allocate and initialize new request set structure with flow control
 * extension. This extension allows to control the number of requests in-flight
 * for the whole set. A callback function to generate requests must be provided
 * and the request set will keep the number of requests sent over the wire to
 * @max_inflight.
 *
 * Returns a pointer to the newly allocated set structure or NULL on error.
 */
struct ptlrpc_request_set *ptlrpc_prep_fcset(int max, set_producer_func func,
					     void *arg)

{
	struct ptlrpc_request_set *set;

	set = ptlrpc_prep_set();
	if (!set)
		RETURN(NULL);

	set->set_max_inflight  = max;
	set->set_producer      = func;
	set->set_producer_arg  = arg;

	RETURN(set);
}

/**
 * ptlrpc_set_destroy() - Free request set structure
 * @set: ptlrpc_request_set to be destroyed
 *
 * Wind down and free request set structure previously allocated with
 * ptlrpc_prep_set. Ensures that all requests on the set have completed and
 * removes all requests from the request list in a set. If any unsent request
 * happen to be on the list, pretends that they got an error in flight and calls
 * their completion handler.
 */
void ptlrpc_set_destroy(struct ptlrpc_request_set *set)
{
	struct ptlrpc_request *req;
	int expected_phase;
	int n = 0;

	ENTRY;

	/* Requests on the set should either all be completed, or all be new */
	expected_phase = (atomic_read(&set->set_remaining) == 0) ?
			 RQ_PHASE_COMPLETE : RQ_PHASE_NEW;
	list_for_each_entry(req, &set->set_requests, rq_set_chain) {
		LASSERT(req->rq_phase == expected_phase);
		n++;
	}

	LASSERTF(atomic_read(&set->set_remaining) == 0 ||
		 atomic_read(&set->set_remaining) == n, "%d / %d\n",
		 atomic_read(&set->set_remaining), n);

	while ((req = list_first_entry_or_null(&set->set_requests,
					       struct ptlrpc_request,
					       rq_set_chain))) {
		list_del_init(&req->rq_set_chain);

		LASSERT(req->rq_phase == expected_phase);

		if (req->rq_phase == RQ_PHASE_NEW) {
			ptlrpc_req_interpret(NULL, req, -EBADR);
			atomic_dec(&set->set_remaining);
		}

		spin_lock(&req->rq_lock);
		req->rq_set = NULL;
		req->rq_invalid_rqset = 0;
		spin_unlock(&req->rq_lock);

		ptlrpc_req_put(req);
	}

	LASSERT(atomic_read(&set->set_remaining) == 0);

	kref_put(&set->set_refcount, ptlrpc_reqset_free);
	EXIT;
}
EXPORT_SYMBOL(ptlrpc_set_destroy);

/**
 * ptlrpc_set_add_req() - Add a new request to the general purpose request set.
 * Assumes request reference from the caller.
 * @set: request set(group of multiple RPCs) where request will be added
 * @req: Request to be added
 */
void ptlrpc_set_add_req(struct ptlrpc_request_set *set,
			struct ptlrpc_request *req)
{
	if (set == PTLRPCD_SET) {
		ptlrpcd_add_req(req);
		return;
	}

	LASSERT(req->rq_import->imp_state != LUSTRE_IMP_IDLE);
	LASSERT(list_empty(&req->rq_set_chain));

	if (req->rq_allow_intr)
		set->set_allow_intr = 1;

	/* The set takes over the caller's request reference */
	list_add_tail(&req->rq_set_chain, &set->set_requests);
	req->rq_set = set;
	atomic_inc(&set->set_remaining);
	req->rq_queued_time_ns = ktime_get_real();

	if (req->rq_reqmsg)
		lustre_msg_set_jobinfo(req->rq_reqmsg, NULL);

	if (set->set_producer)
		/*
		 * If the request set has a producer callback, the RPC must be
		 * sent straight away
		 */
		ptlrpc_send_new_req(req);
}
EXPORT_SYMBOL(ptlrpc_set_add_req);

/**
 * ptlrpc_set_add_new_req() - Add a request to a request set
 * @pc: pointer to ptlrpcd_ctl (dedicated server thread, ie ptlrpcd)
 * @req: request to get added
 *
 * Add a request to a request with dedicated server thread (ptlrpcd) and wake
 * the thread to make any necessary processing. Currently only used for ptlrpcd.
 */
void ptlrpc_set_add_new_req(struct ptlrpcd_ctl *pc,
			    struct ptlrpc_request *req)
{
	struct ptlrpc_request_set *set = pc->pc_set;
	int count, i;

	LASSERT(req->rq_set == NULL);
	LASSERT(test_bit(LIOD_STOP, &pc->pc_flags) == 0);

	spin_lock(&set->set_new_req_lock);
	/*
	 * The set takes over the caller's request reference.
	 */
	req->rq_set = set;
	req->rq_queued_time_ns = ktime_get_real();
	list_add_tail(&req->rq_set_chain, &set->set_new_requests);
	count = atomic_inc_return(&set->set_new_count);
	spin_unlock(&set->set_new_req_lock);

	/* Only need to call wakeup once for the first entry. */
	if (count == 1) {
		wake_up(&set->set_waitq);

		/*
		 * XXX: It maybe unnecessary to wakeup all the partners. But to
		 *      guarantee the async RPC can be processed ASAP, we have
		 *      no other better choice. It maybe fixed in future.
		 */
		for (i = 0; i < pc->pc_npartners; i++)
			wake_up(&pc->pc_partners[i]->pc_set->set_waitq);
	}
}

/**
 * ptlrpc_import_delay_req() - Determine if the request can be sent
 * @imp: import this request is tied to
 * @req: request to be sent
 * @status: error code [out]
 *
 * Based on the current state of the import, determine if the request
 * can be sent, is an error, or should be delayed.
 * Note: The imp->imp_lock must be held.
 *
 * Return
 * * %1 if this request should be delayed
 * * %0 request cannot be send and status is non-zoro(holds error code)
 * * %0 request can be send and status is 0
 */
static int ptlrpc_import_delay_req(struct obd_import *imp,
				   struct ptlrpc_request *req, int *status)
{
	int delay = 0;

	ENTRY;
	LASSERT(status);
	*status = 0;

	if (req->rq_ctx_init || req->rq_ctx_fini) {
		/* always allow ctx init/fini rpc go through */
	} else if (imp->imp_state == LUSTRE_IMP_NEW) {
		DEBUG_REQ(D_ERROR, req, "Uninitialized import");
		*status = -EIO;
	} else if (imp->imp_state == LUSTRE_IMP_CLOSED) {
		unsigned int opc = lustre_msg_get_opc(req->rq_reqmsg);

		/*
		 * pings or MDS-equivalent STATFS may safely
		 * race with umount
		 */
		DEBUG_REQ((opc == OBD_PING || opc == OST_STATFS) ?
			  D_HA : D_ERROR, req, "IMP_CLOSED");
		*status = -EIO;
	} else if (ptlrpc_send_limit_expired(req)) {
		/* probably doesn't need to be a D_ERROR afterinitial testing */
		DEBUG_REQ(D_HA, req, "send limit expired");
		*status = -ETIMEDOUT;
	} else if (req->rq_send_state == LUSTRE_IMP_CONNECTING &&
		   imp->imp_state == LUSTRE_IMP_CONNECTING) {
		;/* allow CONNECT even if import is invalid */
		if (atomic_read(&imp->imp_inval_count) != 0) {
			DEBUG_REQ(D_ERROR, req, "invalidate in flight");
			*status = -EIO;
		}
	} else if (imp->imp_invalid || imp->imp_obd->obd_no_recov) {
		if (!imp->imp_deactive)
			DEBUG_REQ(D_NET, req, "IMP_INVALID");
		*status = -ESHUTDOWN; /* b=12940 */
	} else if (req->rq_import_generation != imp->imp_generation) {
		DEBUG_REQ(req->rq_no_resend ? D_INFO : D_ERROR,
			  req, "req wrong generation:");
		*status = -EIO;
	} else if (req->rq_send_state != imp->imp_state) {
		/* invalidate in progress - any requests should be drop */
		if (atomic_read(&imp->imp_inval_count) != 0) {
			DEBUG_REQ(D_ERROR, req, "invalidate in flight");
			*status = -EIO;
		} else if (req->rq_no_delay &&
			   imp->imp_generation != imp->imp_initiated_at) {
			/* ignore nodelay for requests initiating connections */
			*status = -EAGAIN;
		} else if (req->rq_allow_replay &&
			   (imp->imp_state == LUSTRE_IMP_REPLAY ||
			    imp->imp_state == LUSTRE_IMP_REPLAY_LOCKS ||
			    imp->imp_state == LUSTRE_IMP_REPLAY_WAIT ||
			    imp->imp_state == LUSTRE_IMP_RECOVER)) {
			DEBUG_REQ(D_HA, req, "allow during recovery");
		} else {
			delay = 1;
		}
	}

	RETURN(delay);
}

/**
 * ptlrpc_console_allow() - Decide if the error message should be printed to
 * the console or not. Makes its decision based on request type, status, and
 * failure frequency.
 * @req: request that failed and may need a console message
 * @opc: OST requests type
 * @err: Error associated with @req
 *
 * Return:
 * * %false if no message should be printed
 * * %true if console message should be printed
 */
static bool ptlrpc_console_allow(struct ptlrpc_request *req, __u32 opc, int err)
{
	LASSERT(req->rq_reqmsg != NULL);

	/* Suppress particular reconnect errors which are to be expected. */
	if (opc == OST_CONNECT || opc == OST_DISCONNECT ||
	    opc == MDS_CONNECT || opc == MDS_DISCONNECT ||
	    opc == MGS_CONNECT || opc == MGS_DISCONNECT) {
		/* Suppress timed out reconnect/disconnect requests */
		if (lustre_handle_is_used(&req->rq_import->imp_remote_handle) ||
		    req->rq_timedout)
			return false;

		/*
		 * Suppress most unavailable/again reconnect requests, but
		 * print occasionally so it is clear client is trying to
		 * connect to a server where no target is running.
		 */
		if ((err == -ENODEV || err == -EAGAIN) &&
		    req->rq_import->imp_conn_cnt % 30 != 20)
			return false;
	}

	if (opc == LDLM_ENQUEUE && err == -EAGAIN)
		/* -EAGAIN is normal when using POSIX flocks */
		return false;

	if (opc == OBD_PING && (err == -ENODEV || err == -ENOTCONN) &&
	    (req->rq_xid & 0xf) != 10)
		/* Suppress most ping requests, they may fail occasionally */
		return false;

	return true;
}

/*
 * Check request processing status.
 * Returns the status.
 */
static int ptlrpc_check_status(struct ptlrpc_request *req)
{
	struct obd_import *imp = req->rq_import;
	int rc;

	ENTRY;
	rc = lustre_msg_get_status(req->rq_repmsg);
	if (lustre_msg_get_type(req->rq_repmsg) == PTL_RPC_MSG_ERR) {
		struct lnet_nid *nid = &imp->imp_connection->c_peer.nid;
		__u32 opc = lustre_msg_get_opc(req->rq_reqmsg);

		if (ptlrpc_console_allow(req, opc, rc))
			LCONSOLE_ERROR("%s: operation %s to node %s failed: rc = %d\n",
				       imp->imp_obd->obd_name,
				       ll_opcode2str(opc),
				       libcfs_nidstr(nid), rc);
		RETURN(rc < 0 ? rc : -EINVAL);
	}

	if (rc) {
		DEBUG_REQ(D_INFO, req, "check status: rc = %d", rc);
		if (lustre_msg_get_flags(req->rq_repmsg) & MSG_CLIENT_BANNED) {
			static time64_t last_ban_time;
			time64_t current_time;

			current_time = ktime_get_real_seconds();
			if (current_time > last_ban_time + 6 * 3600) {
				char fsname[LUSTRE_MAXFSNAME + 1];

				if (server_name2fsname(imp->imp_obd->obd_name,
						       fsname, NULL))
					strscpy(fsname, imp->imp_obd->obd_name,
						sizeof(fsname));
				last_ban_time = current_time;
				/* The below message is checked in
				 * sanity-sec test_81
				 */
				LCONSOLE_WARN("This client was banned by administrative request for file system %s. All requests will get Operation not permitted.\n",
					      fsname);
			}
		}
	}

	RETURN(rc);
}

/*
 * save pre-versions of objects into request for replay.
 * Versions are obtained from server reply.
 * used for VBR.
 */
static void ptlrpc_save_versions(struct ptlrpc_request *req)
{
	struct lustre_msg *repmsg = req->rq_repmsg;
	struct lustre_msg *reqmsg = req->rq_reqmsg;
	__u64 *versions = lustre_msg_get_versions(repmsg);

	ENTRY;
	if (lustre_msg_get_flags(req->rq_reqmsg) & MSG_REPLAY)
		return;

	LASSERT(versions);
	lustre_msg_set_versions(reqmsg, versions);
	CDEBUG(D_INFO, "Client save versions [%#llx/%#llx]\n",
	       versions[0], versions[1]);

	EXIT;
}

__u64 ptlrpc_known_replied_xid(struct obd_import *imp)
{
	struct ptlrpc_request *req;

	assert_spin_locked(&imp->imp_lock);
	if (list_empty(&imp->imp_unreplied_list))
		return 0;

	req = list_first_entry(&imp->imp_unreplied_list, struct ptlrpc_request,
			       rq_unreplied_list);
	LASSERTF(req->rq_xid >= 1, "XID:%llu\n", req->rq_xid);

	if (imp->imp_known_replied_xid < req->rq_xid - 1)
		imp->imp_known_replied_xid = req->rq_xid - 1;

	return req->rq_xid - 1;
}

/*
 * Callback function called when client receives RPC reply for req.
 * The return value would be assigned to req->rq_status by the caller
 * as request processing status.
 * This function also decides if the request needs to be saved for later replay.
 * Returns 0 on success or error code.
 */
static int after_reply(struct ptlrpc_request *req)
{
	struct obd_import *imp = req->rq_import;
	struct obd_device *obd = req->rq_import->imp_obd;
	ktime_t work_start;
	u64 committed;
	s64 timediff;
	int rc;

	ENTRY;
	LASSERT(obd != NULL);
	/* repbuf must be unlinked */
	LASSERT(!req->rq_receiving_reply && req->rq_reply_unlinked);

	if (req->rq_reply_truncated) {
		if (ptlrpc_no_resend(req)) {
			DEBUG_REQ(D_ERROR, req,
				  "reply buffer overflow, expected=%d, actual size=%d",
				  req->rq_nob_received, req->rq_repbuf_len);
			RETURN(-EOVERFLOW);
		}

		sptlrpc_cli_free_repbuf(req);
		/*
		 * Pass the required reply buffer size (include
		 * space for early reply).
		 * NB: no need to roundup because alloc_repbuf
		 * will roundup it
		 */
		req->rq_replen = req->rq_nob_received;
		req->rq_nob_received = 0;
		spin_lock(&req->rq_lock);
		req->rq_resend       = 1;
		spin_unlock(&req->rq_lock);
		RETURN(0);
	}

	work_start = ktime_get_real();
	timediff = ktime_us_delta(work_start, req->rq_sent_ns);
	if (unlikely(timediff < 0))
		timediff = 1;

	/*
	 * NB Until this point, the whole of the incoming message,
	 * including buflens, status etc is in the sender's byte order.
	 */
	rc = sptlrpc_cli_unwrap_reply(req);
	if (rc) {
		DEBUG_REQ(D_ERROR, req, "unwrap reply failed: rc = %d", rc);
		RETURN(rc);
	}

	/*
	 * Security layer unwrap might ask resend this request.
	 */
	if (req->rq_resend)
		RETURN(0);

	rc = unpack_reply(req);
	if (rc)
		RETURN(rc);

	/* retry indefinitely on EINPROGRESS */
	if (lustre_msg_get_status(req->rq_repmsg) == -EINPROGRESS &&
	    ptlrpc_no_resend(req) == 0 && !req->rq_no_retry_einprogress) {
		time64_t now = ktime_get_real_seconds();

		DEBUG_REQ((req->rq_nr_resend % 8 == 1 ? D_WARNING : 0) |
			  D_RPCTRACE, req, "resending request on EINPROGRESS");
		spin_lock(&req->rq_lock);
		req->rq_resend = 1;
		spin_unlock(&req->rq_lock);
		req->rq_nr_resend++;

		/* Readjust the timeout for current conditions */
		ptlrpc_at_set_req_timeout(req);
		/*
		 * delay resend to give a chance to the server to get ready.
		 * The delay is increased by 1s on every resend and is capped to
		 * the current request timeout (i.e. obd_timeout if AT is off,
		 * or AT service time x 125% + 5s, see at_est2timeout)
		 */
		if (req->rq_nr_resend > req->rq_timeout)
			req->rq_sent = now + req->rq_timeout;
		else
			req->rq_sent = now + req->rq_nr_resend;

		/* Resend for EINPROGRESS will use a new XID */
		spin_lock(&imp->imp_lock);
		list_del_init(&req->rq_unreplied_list);
		spin_unlock(&imp->imp_lock);

		RETURN(0);
	}

	if (obd->obd_svc_stats) {
		s64 qtime = ktime_us_delta(work_start, req->rq_queued_time_ns);
		lprocfs_counter_add(obd->obd_svc_stats, PTLRPC_REQWAIT_CNTR,
				    qtime);
		ptlrpc_lprocfs_rpc_sent(req, timediff);
	}

	if (lustre_msg_get_type(req->rq_repmsg) != PTL_RPC_MSG_REPLY &&
	    lustre_msg_get_type(req->rq_repmsg) != PTL_RPC_MSG_ERR) {
		DEBUG_REQ(D_ERROR, req, "invalid packet received (type=%u)",
			  lustre_msg_get_type(req->rq_repmsg));
		RETURN(-EPROTO);
	}

	if (lustre_msg_get_opc(req->rq_reqmsg) != OBD_PING)
		CFS_FAIL_TIMEOUT(OBD_FAIL_PTLRPC_PAUSE_REP, cfs_fail_val);
	ptlrpc_at_adj_service(req, lustre_msg_get_timeout(req->rq_repmsg));
	ptlrpc_at_adj_net_latency(req,
				  lustre_msg_get_service_timeout(req->rq_repmsg));

	rc = ptlrpc_check_status(req);

	if (rc) {
		/*
		 * Either we've been evicted, or the server has failed for
		 * some reason. Try to reconnect, and if that fails, punt to
		 * the upcall.
		 */
		if (ptlrpc_recoverable_error(rc)) {
			if (req->rq_send_state != LUSTRE_IMP_FULL ||
			    imp->imp_obd->obd_no_recov || imp->imp_dlm_fake) {
				RETURN(rc);
			}
			ptlrpc_request_handle_notconn(req);
			RETURN(rc);
		}
	} else {
		/*
		 * Let's look if server sent slv. Do it only for RPC with
		 * rc == 0.
		 */
		ldlm_cli_update_pool(req);
	}

	/*
	 * Store transno in reqmsg for replay.
	 */
	if (!(lustre_msg_get_flags(req->rq_reqmsg) & MSG_REPLAY)) {
		req->rq_transno = lustre_msg_get_transno(req->rq_repmsg);
		lustre_msg_set_transno(req->rq_reqmsg, req->rq_transno);
	}

	if (lustre_msg_get_transno(req->rq_repmsg) ||
	    lustre_msg_get_opc(req->rq_reqmsg) == LDLM_ENQUEUE)
		imp->imp_no_cached_data = 0;

	if (imp->imp_replayable) {
		/* if other threads are waiting for ptlrpc_free_committed()
		 * they could continue the work of freeing RPCs. That reduces
		 * lock hold times, and distributes work more fairly across
		 * waiting threads.  We can't use spin_is_contended() since
		 * there are many other places where imp_lock is held.
		 */
		atomic_inc(&imp->imp_waiting);
		spin_lock(&imp->imp_lock);
		atomic_dec(&imp->imp_waiting);
		/*
		 * No point in adding already-committed requests to the replay
		 * list, we will just remove them immediately. b=9829
		 */
		if (req->rq_transno != 0 &&
		    (req->rq_transno >
		     lustre_msg_get_last_committed(req->rq_repmsg) ||
		     req->rq_replay)) {
			/** version recovery */
			ptlrpc_save_versions(req);
			ptlrpc_retain_replayable_request(req, imp);
		} else if (req->rq_commit_cb &&
			   list_empty(&req->rq_replay_list)) {
			/*
			 * NB: don't call rq_commit_cb if it's already on
			 * rq_replay_list, ptlrpc_free_committed() will call
			 * it later, see LU-3618 for details
			 */
			spin_unlock(&imp->imp_lock);
			req->rq_commit_cb(req);
			atomic_inc(&imp->imp_waiting);
			spin_lock(&imp->imp_lock);
			atomic_dec(&imp->imp_waiting);
		}

		/*
		 * Replay-enabled imports return commit-status information.
		 */
		committed = lustre_msg_get_last_committed(req->rq_repmsg);
		if (likely(committed > imp->imp_peer_committed_transno))
			imp->imp_peer_committed_transno = committed;

		ptlrpc_free_committed(imp);

		if (!list_empty(&imp->imp_replay_list)) {
			struct ptlrpc_request *last;

			last = list_entry(imp->imp_replay_list.prev,
					  struct ptlrpc_request,
					  rq_replay_list);
			/*
			 * Requests with rq_replay stay on the list even if no
			 * commit is expected.
			 */
			if (last->rq_transno > imp->imp_peer_committed_transno)
				ptlrpc_pinger_commit_expected(imp);
		}

		spin_unlock(&imp->imp_lock);
	}

	RETURN(rc);
}

/**
 * ptlrpc_send_new_req() - Helper function to send request @req over the network
 * for the first time. Also adjusts request phase.
 * @req: request to be added
 *
 * Returns 0 on success or error code on failure
 */
static int ptlrpc_send_new_req(struct ptlrpc_request *req)
{
	struct obd_import *imp = req->rq_import;
	__u64 min_xid = 0;
	int rc;

	ENTRY;
	LASSERT(req->rq_phase == RQ_PHASE_NEW);

	/* do not try to go further if there is not enough memory in pool */
	if (req->rq_sent && req->rq_bulk)
		if (req->rq_bulk->bd_iov_count >
		    obd_pool_get_free_objects(0) &&
		    pool_is_at_full_capacity(0))
			RETURN(-ENOMEM);

	if (req->rq_sent && (req->rq_sent > ktime_get_real_seconds()) &&
	    (!req->rq_generation_set ||
	     req->rq_import_generation == imp->imp_generation))
		RETURN(0);

	ptlrpc_rqphase_move(req, RQ_PHASE_RPC);

	spin_lock(&imp->imp_lock);

	LASSERT(req->rq_xid != 0);
	LASSERT(!list_empty(&req->rq_unreplied_list));

	if (!req->rq_generation_set)
		req->rq_import_generation = imp->imp_generation;

	if (ptlrpc_import_delay_req(imp, req, &rc)) {
		spin_lock(&req->rq_lock);
		req->rq_waiting = 1;
		spin_unlock(&req->rq_lock);

		DEBUG_REQ(D_HA, req, "req waiting for recovery: (%s != %s)",
			  ptlrpc_import_state_name(req->rq_send_state),
			  ptlrpc_import_state_name(imp->imp_state));
		LASSERT(list_empty(&req->rq_list));
		list_add_tail(&req->rq_list, &imp->imp_delayed_list);
		atomic_inc(&req->rq_import->imp_inflight);
		spin_unlock(&imp->imp_lock);
		RETURN(0);
	}

	if (rc != 0) {
		spin_unlock(&imp->imp_lock);
		req->rq_status = rc;
		ptlrpc_rqphase_move(req, RQ_PHASE_INTERPRET);
		RETURN(rc);
	}

	LASSERT(list_empty(&req->rq_list));
	list_add_tail(&req->rq_list, &imp->imp_sending_list);
	atomic_inc(&req->rq_import->imp_inflight);

	/*
	 * find the known replied XID from the unreplied list, CONNECT
	 * and DISCONNECT requests are skipped to make the sanity check
	 * on server side happy. see process_req_last_xid().
	 *
	 * For CONNECT: Because replay requests have lower XID, it'll
	 * break the sanity check if CONNECT bump the exp_last_xid on
	 * server.
	 *
	 * For DISCONNECT: Since client will abort inflight RPC before
	 * sending DISCONNECT, DISCONNECT may carry an XID which higher
	 * than the inflight RPC.
	 */
	if (!ptlrpc_req_is_connect(req) && !ptlrpc_req_is_disconnect(req))
		min_xid = ptlrpc_known_replied_xid(imp);
	spin_unlock(&imp->imp_lock);

	lustre_msg_set_last_xid(req->rq_reqmsg, min_xid);

	lustre_msg_set_status(req->rq_reqmsg, current->pid);

	/* If the request to be sent is an LDLM callback, do not try to
	 * refresh context.
	 * An LDLM callback is sent by a server to a client in order to make
	 * it release a lock, on a communication channel that uses a reverse
	 * context. It cannot be refreshed on its own, as it is the 'reverse'
	 * (server-side) representation of a client context.
	 * We do not care if the reverse context is expired, and want to send
	 * the LDLM callback anyway. Once the client receives the AST, it is
	 * its job to refresh its own context if it has expired, hence
	 * refreshing the associated reverse context on server side, before
	 * being able to send the LDLM_CANCEL requested by the server.
	 */
	if (lustre_msg_get_opc(req->rq_reqmsg) != LDLM_BL_CALLBACK &&
	    lustre_msg_get_opc(req->rq_reqmsg) != LDLM_CP_CALLBACK &&
	    lustre_msg_get_opc(req->rq_reqmsg) != LDLM_GL_CALLBACK)
		rc = sptlrpc_req_refresh_ctx(req, 0);
	if (rc) {
		if (req->rq_err) {
			req->rq_status = rc;
			RETURN(1);
		} else {
			spin_lock(&req->rq_lock);
			req->rq_wait_ctx = 1;
			spin_unlock(&req->rq_lock);
			RETURN(0);
		}
	}

	CDEBUG(D_RPCTRACE,
	       "Sending RPC req@%p pname:cluuid:pid:xid:nid:opc:job %s:%s:%d:%llu:%s:%d:%s\n",
	       req, current->comm,
	       imp->imp_obd->obd_uuid.uuid,
	       lustre_msg_get_status(req->rq_reqmsg), req->rq_xid,
	       obd_import_nid2str(imp), lustre_msg_get_opc(req->rq_reqmsg),
	       lustre_msg_get_jobid(req->rq_reqmsg) ?: "");

	rc = ptl_send_rpc(req, 0);
	if (rc == -ENOMEM) {
		spin_lock(&imp->imp_lock);
		if (!list_empty(&req->rq_list)) {
			list_del_init(&req->rq_list);
			if (atomic_dec_and_test(&req->rq_import->imp_inflight))
				wake_up(&req->rq_import->imp_recovery_waitq);
		}
		spin_unlock(&imp->imp_lock);
		ptlrpc_rqphase_move(req, RQ_PHASE_NEW);
		RETURN(rc);
	}
	if (rc) {
		DEBUG_REQ(D_HA, req, "send failed, expect timeout: rc = %d",
			  rc);
		spin_lock(&req->rq_lock);
		req->rq_net_err = 1;
		spin_unlock(&req->rq_lock);
		RETURN(rc);
	}
	RETURN(0);
}

static inline int ptlrpc_set_producer(struct ptlrpc_request_set *set)
{
	int remaining, rc;

	ENTRY;
	LASSERT(set->set_producer != NULL);

	remaining = atomic_read(&set->set_remaining);

	/*
	 * populate the ->set_requests list with requests until we
	 * reach the maximum number of RPCs in flight for this set
	 */
	while (atomic_read(&set->set_remaining) < set->set_max_inflight) {
		rc = set->set_producer(set, set->set_producer_arg);
		if (rc == -ENOENT) {
			/* no more RPC to produce */
			set->set_producer     = NULL;
			set->set_producer_arg = NULL;
			RETURN(0);
		}
	}

	RETURN((atomic_read(&set->set_remaining) - remaining));
}

/**
 * ptlrpc_check_set() - sends any unsent RPCs in set
 * @env: execution environment
 * @set: ptlrpc_request_set all request in a set
 *
 * This sends any unsent RPCs in @set and returns 1 if all are sent
 * and no more replies are expected. (it is possible to get less replies than
 * requests sent e.g. due to timed out requests or requests that we had trouble
 * to send out)
 *
 * NOTE: This function contains a potential schedule point (cond_resched()).
 *
 * Returns 0 on success or error code otherwise.
 */
int ptlrpc_check_set(const struct lu_env *env, struct ptlrpc_request_set *set)
{
	struct ptlrpc_request *req, *next;
	LIST_HEAD(comp_reqs);
	int force_timer_recalc = 0;

	ENTRY;
	if (atomic_read(&set->set_remaining) == 0)
		RETURN(1);

	list_for_each_entry_safe(req, next, &set->set_requests,
				 rq_set_chain) {
		struct obd_import *imp = req->rq_import;
		int unregistered = 0;
		int async = 1;
		int rc = 0;

		if (req->rq_phase == RQ_PHASE_COMPLETE) {
			list_move_tail(&req->rq_set_chain, &comp_reqs);
			continue;
		}

		/*
		 * This schedule point is mainly for the ptlrpcd caller of this
		 * function.  Most ptlrpc sets are not long-lived and unbounded
		 * in length, but at the least the set used by the ptlrpcd is.
		 * Since the processing time is unbounded, we need to insert an
		 * explicit schedule point to make the thread well-behaved.
		 */
		cond_resched();

		/*
		 * If the caller requires to allow to be interpreted by force
		 * and it has really been interpreted, then move the request
		 * to RQ_PHASE_INTERPRET phase in spite of what the current
		 * phase is.
		 */
		if (unlikely(req->rq_allow_intr && req->rq_intr)) {
			req->rq_status = -EINTR;
			ptlrpc_rqphase_move(req, RQ_PHASE_INTERPRET);

			/*
			 * Since it is interpreted and we have to wait for
			 * the reply to be unlinked, then use sync mode.
			 */
			async = 0;

			GOTO(interpret, req->rq_status);
		}

		if (req->rq_phase == RQ_PHASE_NEW && ptlrpc_send_new_req(req))
			force_timer_recalc = 1;

		/* delayed send - skip */
		if (req->rq_phase == RQ_PHASE_NEW && req->rq_sent)
			continue;

		/* delayed resend - skip */
		if (req->rq_phase == RQ_PHASE_RPC && req->rq_resend &&
		    req->rq_sent > ktime_get_real_seconds())
			continue;

		if (!(req->rq_phase == RQ_PHASE_RPC ||
		      req->rq_phase == RQ_PHASE_BULK ||
		      req->rq_phase == RQ_PHASE_INTERPRET ||
		      req->rq_phase == RQ_PHASE_UNREG_RPC ||
		      req->rq_phase == RQ_PHASE_UNREG_BULK)) {
			DEBUG_REQ(D_ERROR, req, "bad phase %x", req->rq_phase);
			LBUG();
		}

		if (req->rq_phase == RQ_PHASE_UNREG_RPC ||
		    req->rq_phase == RQ_PHASE_UNREG_BULK) {
			LASSERT(req->rq_next_phase != req->rq_phase);
			LASSERT(req->rq_next_phase != RQ_PHASE_UNDEFINED);

			if (req->rq_req_deadline &&
			    !CFS_FAIL_CHECK(OBD_FAIL_PTLRPC_LONG_REQ_UNLINK))
				req->rq_req_deadline = 0;
			if (req->rq_reply_deadline &&
			    !CFS_FAIL_CHECK(OBD_FAIL_PTLRPC_LONG_REPL_UNLINK))
				req->rq_reply_deadline = 0;
			if (req->rq_bulk_deadline &&
			    !CFS_FAIL_CHECK(OBD_FAIL_PTLRPC_LONG_BULK_UNLINK))
				req->rq_bulk_deadline = 0;

			/*
			 * Skip processing until reply is unlinked. We
			 * can't return to pool before that and we can't
			 * call interpret before that. We need to make
			 * sure that all rdma transfers finished and will
			 * not corrupt any data.
			 */
			if (req->rq_phase == RQ_PHASE_UNREG_RPC &&
			    ptlrpc_client_recv_or_unlink(req))
				continue;
			if (req->rq_phase == RQ_PHASE_UNREG_BULK &&
			    ptlrpc_client_bulk_active(req))
				continue;

			/*
			 * Turn fail_loc off to prevent it from looping
			 * forever.
			 */
			if (CFS_FAIL_CHECK(OBD_FAIL_PTLRPC_LONG_REPL_UNLINK)) {
				CFS_FAIL_CHECK_ORSET(OBD_FAIL_PTLRPC_LONG_REPL_UNLINK,
						     CFS_FAIL_ONCE);
			}
			if (CFS_FAIL_CHECK(OBD_FAIL_PTLRPC_LONG_BULK_UNLINK)) {
				CFS_FAIL_CHECK_ORSET(OBD_FAIL_PTLRPC_LONG_BULK_UNLINK,
						     CFS_FAIL_ONCE);
			}

			/*
			 * Move to next phase if reply was successfully
			 * unlinked.
			 */
			ptlrpc_rqphase_move(req, req->rq_next_phase);
		}

		if (req->rq_phase == RQ_PHASE_INTERPRET)
			GOTO(interpret, req->rq_status);

		/*
		 * Note that this also will start async reply unlink.
		 */
		if (req->rq_net_err && !req->rq_timedout) {
			ptlrpc_expire_one_request(req, 1);

			/*
			 * Check if we still need to wait for unlink.
			 */
			if (ptlrpc_client_recv_or_unlink(req) ||
			    ptlrpc_client_bulk_active(req))
				continue;
			/* If there is no need to resend, fail it now. */
			if (req->rq_no_resend) {
				if (req->rq_status == 0)
					req->rq_status = -EIO;
				ptlrpc_rqphase_move(req, RQ_PHASE_INTERPRET);
				GOTO(interpret, req->rq_status);
			} else {
				continue;
			}
		}

		if (req->rq_err) {
			if (!ptlrpc_unregister_reply(req, 1)) {
				ptlrpc_unregister_bulk(req, 1);
				continue;
			}

			spin_lock(&req->rq_lock);
			req->rq_replied = 0;
			spin_unlock(&req->rq_lock);
			if (req->rq_status == 0)
				req->rq_status = -EIO;
			ptlrpc_rqphase_move(req, RQ_PHASE_INTERPRET);
			GOTO(interpret, req->rq_status);
		}

		/*
		 * ptlrpc_set_wait uses wait_woken()
		 * so it sets rq_intr regardless of individual rpc
		 * timeouts. The synchronous IO waiting path sets
		 * rq_intr irrespective of whether ptlrpcd
		 * has seen a timeout.  Our policy is to only interpret
		 * interrupted rpcs after they have timed out, so we
		 * need to enforce that here.
		 */

		if (req->rq_intr && (req->rq_timedout || req->rq_waiting ||
				     req->rq_wait_ctx)) {
			req->rq_status = -EINTR;
			ptlrpc_rqphase_move(req, RQ_PHASE_INTERPRET);
			GOTO(interpret, req->rq_status);
		}

		if (req->rq_phase == RQ_PHASE_RPC) {
			if (req->rq_timedout || req->rq_resend ||
			    req->rq_waiting || req->rq_wait_ctx) {
				int status;

				if (!ptlrpc_unregister_reply(req, 1)) {
					ptlrpc_unregister_bulk(req, 1);
					continue;
				}

				spin_lock(&imp->imp_lock);
				if (ptlrpc_import_delay_req(imp, req,
							    &status)) {
					/*
					 * put on delay list - only if we wait
					 * recovery finished - before send
					 */
					list_move_tail(&req->rq_list,
						       &imp->imp_delayed_list);
					spin_unlock(&imp->imp_lock);
					continue;
				}

				if (status != 0)  {
					req->rq_status = status;
					ptlrpc_rqphase_move(req,
							    RQ_PHASE_INTERPRET);
					spin_unlock(&imp->imp_lock);
					GOTO(interpret, req->rq_status);
				}
				/* ignore on just initiated connections */
				if (ptlrpc_no_resend(req) &&
				    !req->rq_wait_ctx &&
				    imp->imp_generation !=
				    imp->imp_initiated_at) {
					req->rq_status = -ENOTCONN;
					ptlrpc_rqphase_move(req,
							    RQ_PHASE_INTERPRET);
					spin_unlock(&imp->imp_lock);
					GOTO(interpret, req->rq_status);
				}

				/* don't resend too fast in case of network
				 * errors.
				 */
				if (ktime_get_real_seconds() < (req->rq_sent + 1)
				    && req->rq_net_err && req->rq_timedout) {

					DEBUG_REQ(D_INFO, req,
						  "throttle request");
					/* Don't try to resend RPC right away
					 * as it is likely it will fail again
					 * and ptlrpc_check_set() will be
					 * called again, keeping this thread
					 * busy. Instead, wait for the next
					 * timeout. Flag it as resend to
					 * ensure we don't wait to long.
					 */
					req->rq_resend = 1;
					spin_unlock(&imp->imp_lock);
					continue;
				}

				list_move_tail(&req->rq_list,
					       &imp->imp_sending_list);

				spin_unlock(&imp->imp_lock);

				spin_lock(&req->rq_lock);
				req->rq_waiting = 0;
				spin_unlock(&req->rq_lock);

				if (req->rq_timedout || req->rq_resend) {
					/*
					 * This is re-sending anyways,
					 * let's mark req as resend.
					 */
					spin_lock(&req->rq_lock);
					req->rq_resend = 1;
					spin_unlock(&req->rq_lock);
				}
				/*
				 * rq_wait_ctx is only touched by ptlrpcd,
				 * so no lock is needed here.
				 */
				status = sptlrpc_req_refresh_ctx(req, 0);
				if (status) {
					if (req->rq_err) {
						req->rq_status = status;
						spin_lock(&req->rq_lock);
						req->rq_wait_ctx = 0;
						spin_unlock(&req->rq_lock);
						force_timer_recalc = 1;
					} else {
						spin_lock(&req->rq_lock);
						req->rq_wait_ctx = 1;
						spin_unlock(&req->rq_lock);
					}

					continue;
				} else {
					spin_lock(&req->rq_lock);
					req->rq_wait_ctx = 0;
					spin_unlock(&req->rq_lock);
				}

				/*
				 * In any case, the previous bulk should be
				 * cleaned up to prepare for the new sending
				 */
				if (req->rq_bulk &&
				    !ptlrpc_unregister_bulk(req, 1))
					continue;

				rc = ptl_send_rpc(req, 0);
				if (rc == -ENOMEM) {
					spin_lock(&imp->imp_lock);
					if (!list_empty(&req->rq_list)) {
						list_del_init(&req->rq_list);
						if (atomic_dec_and_test(&imp->imp_inflight))
							wake_up(&imp->imp_recovery_waitq);
					}
					spin_unlock(&imp->imp_lock);
					ptlrpc_rqphase_move(req, RQ_PHASE_NEW);
					continue;
				}
				if (rc) {
					DEBUG_REQ(D_HA, req,
						  "send failed: rc = %d", rc);
					force_timer_recalc = 1;
					spin_lock(&req->rq_lock);
					req->rq_net_err = 1;
					spin_unlock(&req->rq_lock);
					continue;
				}
				/* need to reset the timeout */
				force_timer_recalc = 1;
			}

			spin_lock(&req->rq_lock);

			if (ptlrpc_client_early(req)) {
				ptlrpc_at_recv_early_reply(req);
				spin_unlock(&req->rq_lock);
				continue;
			}

			/* Still waiting for a reply? */
			if (ptlrpc_client_recv(req)) {
				spin_unlock(&req->rq_lock);
				continue;
			}

			/* Did we actually receive a reply? */
			if (!ptlrpc_client_replied(req)) {
				spin_unlock(&req->rq_lock);
				continue;
			}

			spin_unlock(&req->rq_lock);

			/*
			 * unlink from net because we are going to
			 * swab in-place of reply buffer
			 */
			unregistered = ptlrpc_unregister_reply(req, 1);
			if (!unregistered)
				continue;

			req->rq_status = after_reply(req);
			if (req->rq_resend) {
				force_timer_recalc = 1;
				continue;
			}

			/*
			 * If there is no bulk associated with this request,
			 * then we're done and should let the interpreter
			 * process the reply. Similarly if the RPC returned
			 * an error, and therefore the bulk will never arrive.
			 */
			if (!req->rq_bulk || req->rq_status < 0) {
				ptlrpc_rqphase_move(req, RQ_PHASE_INTERPRET);
				GOTO(interpret, req->rq_status);
			}

			ptlrpc_rqphase_move(req, RQ_PHASE_BULK);
		}

		LASSERT(req->rq_phase == RQ_PHASE_BULK);
		if (ptlrpc_client_bulk_active(req))
			continue;

		if (req->rq_bulk->bd_failure) {
			/*
			 * The RPC reply arrived OK, but the bulk screwed
			 * up!  Dead weird since the server told us the RPC
			 * was good after getting the REPLY for her GET or
			 * the ACK for her PUT.
			 */
			DEBUG_REQ(D_ERROR, req, "bulk transfer failed %d/%d/%d",
				  req->rq_status,
				  req->rq_bulk->bd_nob,
				  req->rq_bulk->bd_nob_transferred);
			req->rq_status = -EIO;
		}

		ptlrpc_rqphase_move(req, RQ_PHASE_INTERPRET);

interpret:
		LASSERT(req->rq_phase == RQ_PHASE_INTERPRET);

		/*
		 * This moves to "unregistering" phase we need to wait for
		 * reply unlink.
		 */
		if (!unregistered && !ptlrpc_unregister_reply(req, async)) {
			/* start async bulk unlink too */
			ptlrpc_unregister_bulk(req, 1);
			continue;
		}

		if (!ptlrpc_unregister_bulk(req, async))
			continue;

		/*
		 * When calling interpret receiving already should be
		 * finished.
		 */
		LASSERT(!req->rq_receiving_reply);

		ptlrpc_req_interpret(env, req, req->rq_status);
		ptlrpc_rqphase_move(req, RQ_PHASE_COMPLETE);

		if (req->rq_reqmsg)
			CDEBUG(D_RPCTRACE,
			       "Completed RPC req@%p pname:cluuid:pid:xid:nid:opc:job %s:%s:%d:%llu:%s:%d:%s\n",
			       req, current->comm,
			       imp->imp_obd->obd_uuid.uuid,
			       lustre_msg_get_status(req->rq_reqmsg),
			       req->rq_xid,
			       obd_import_nid2str(imp),
			       lustre_msg_get_opc(req->rq_reqmsg),
			       lustre_msg_get_jobid(req->rq_reqmsg) ?: "");

		spin_lock(&imp->imp_lock);
		/*
		 * Request already may be not on sending or delaying list. This
		 * may happen in the case of marking it erroneous for the case
		 * ptlrpc_import_delay_req(req, status) find it impossible to
		 * allow sending this rpc and returns *status != 0.
		 */
		if (!list_empty(&req->rq_list)) {
			list_del_init(&req->rq_list);
			if (atomic_dec_and_test(&imp->imp_inflight))
				wake_up(&imp->imp_recovery_waitq);
		}
		list_del_init(&req->rq_unreplied_list);
		spin_unlock(&imp->imp_lock);

		atomic_dec(&set->set_remaining);
		wake_up(&imp->imp_recovery_waitq);

		if (set->set_producer) {
			/* produce a new request if possible */
			if (ptlrpc_set_producer(set) > 0)
				force_timer_recalc = 1;

			/*
			 * free the request that has just been completed
			 * in order not to pollute set->set_requests
			 */
			list_del_init(&req->rq_set_chain);
			spin_lock(&req->rq_lock);
			req->rq_set = NULL;
			req->rq_invalid_rqset = 0;
			spin_unlock(&req->rq_lock);

			/* record rq_status to compute the final status later */
			if (req->rq_status != 0)
				set->set_rc = req->rq_status;
			ptlrpc_req_put(req);
		} else {
			list_move_tail(&req->rq_set_chain, &comp_reqs);
		}
	}

	/*
	 * move completed request at the head of list so it's easier for
	 * caller to find them
	 */
	list_splice(&comp_reqs, &set->set_requests);

	/* If we hit an error, we want to recover promptly. */
	RETURN(atomic_read(&set->set_remaining) == 0 || force_timer_recalc);
}
EXPORT_SYMBOL(ptlrpc_check_set);

/**
 * ptlrpc_expire_one_request() - Time out request
 * @req: request to expire
 * @async_unlink:  if true, that means do not wait. Else if false, wait until
 * LNet actually confirms network buffer unlinking.
 *
 * Return 1 if we should give up further retrying attempts or 0 otherwise.
 */
int ptlrpc_expire_one_request(struct ptlrpc_request *req, int async_unlink)
{
	struct obd_import *imp = req->rq_import;
	unsigned int debug_mask = D_RPCTRACE;
	int rc = 0;
	__u32 opc;
	time64_t real_sent = 0;

	ENTRY;
	spin_lock(&req->rq_lock);
	req->rq_timedout = 1;
	spin_unlock(&req->rq_lock);

	opc = lustre_msg_get_opc(req->rq_reqmsg);
	if (ptlrpc_console_allow(req, opc,
				 lustre_msg_get_status(req->rq_reqmsg)))
		debug_mask = D_WARNING;
	if (req->rq_real_sent_ns)
		real_sent = ktime_divns(req->rq_real_sent_ns, NSEC_PER_SEC);
	/* this message is used in replay-single test_200, DO NOT MODIFY */
	DEBUG_REQ(debug_mask, req, "Request sent has %s: [sent %lld/real %lld]",
		  req->rq_net_err ? "failed due to network error" :
		     ((real_sent == 0 ||
		       real_sent < req->rq_sent ||
		       real_sent >= req->rq_deadline) ?
		      "timed out for sent delay" : "timed out for slow reply"),
		  req->rq_sent, real_sent);

	if (imp && obd_debug_peer_on_timeout)
		LNetDebugPeer(&imp->imp_connection->c_peer);

	ptlrpc_unregister_reply(req, async_unlink);
	ptlrpc_unregister_bulk(req, async_unlink);

	if (obd_dump_on_timeout)
		libcfs_debug_dumplog();

	if (!imp) {
		DEBUG_REQ(D_HA, req, "NULL import: already cleaned up?");
		RETURN(1);
	}

	atomic_inc(&imp->imp_timeouts);

	/* The DLM server doesn't want recovery run on its imports. */
	if (imp->imp_dlm_fake)
		RETURN(1);

	/*
	 * If this request is for recovery or other primordial tasks,
	 * then error it out here.
	 */
	if (req->rq_ctx_init || req->rq_ctx_fini ||
	    req->rq_send_state != LUSTRE_IMP_FULL ||
	    imp->imp_obd->obd_no_recov) {
		DEBUG_REQ(D_RPCTRACE, req, "err -110, sent_state=%s (now=%s)",
			  ptlrpc_import_state_name(req->rq_send_state),
			  ptlrpc_import_state_name(imp->imp_state));
		spin_lock(&req->rq_lock);
		req->rq_status = -ETIMEDOUT;
		req->rq_err = 1;
		spin_unlock(&req->rq_lock);
		RETURN(1);
	}

	/*
	 * if a request can't be resent we can't wait for an answer after
	 * the timeout
	 */
	if (ptlrpc_no_resend(req)) {
		DEBUG_REQ(D_RPCTRACE, req, "TIMEOUT-NORESEND:");
		rc = 1;
	}

	if (opc != OBD_PING || req->rq_xid > imp->imp_highest_replied_xid)
		ptlrpc_fail_import(imp,
				   lustre_msg_get_conn_cnt(req->rq_reqmsg));

	RETURN(rc);
}

/*
 * Time out all uncompleted requests in request set pointed by \a data
 * This is called when a wait times out.
 */
void ptlrpc_expired_set(struct ptlrpc_request_set *set)
{
	struct ptlrpc_request *req;
	time64_t now = ktime_get_real_seconds();

	ENTRY;
	LASSERT(set != NULL);

	/*
	 * A timeout expired. See which reqs it applies to...
	 */
	list_for_each_entry(req, &set->set_requests, rq_set_chain) {
		/* don't expire request waiting for context */
		if (req->rq_wait_ctx)
			continue;

		/* Request in-flight? */
		if (!((req->rq_phase == RQ_PHASE_RPC &&
		       !req->rq_waiting && !req->rq_resend) ||
		      (req->rq_phase == RQ_PHASE_BULK)))
			continue;

		if (req->rq_timedout ||     /* already dealt with */
		    req->rq_deadline > now) /* not expired */
			continue;

		/*
		 * Deal with this guy. Do it asynchronously to not block
		 * ptlrpcd thread.
		 */
		ptlrpc_expire_one_request(req, 1);
		/*
		 * Loops require that we resched once in a while to avoid
		 * RCU stalls and a few other problems.
		 */
		cond_resched();

	}
}

/*
 * Interrupts (sets interrupted flag) all uncompleted requests in
 * a set \a data. This is called when a wait_event is interrupted
 * by a signal.
 */
static void ptlrpc_interrupted_set(struct ptlrpc_request_set *set)
{
	struct ptlrpc_request *req;

	LASSERT(set != NULL);
	CDEBUG(D_RPCTRACE, "INTERRUPTED SET %p\n", set);

	list_for_each_entry(req, &set->set_requests, rq_set_chain) {
		if (req->rq_intr)
			continue;

		if (req->rq_phase != RQ_PHASE_RPC &&
		    req->rq_phase != RQ_PHASE_UNREG_RPC &&
		    !req->rq_allow_intr)
			continue;

		spin_lock(&req->rq_lock);
		req->rq_intr = 1;
		spin_unlock(&req->rq_lock);
	}
}

/*
 * Get the smallest timeout in the set; this does NOT set a timeout.
 */
time64_t ptlrpc_set_next_timeout(struct ptlrpc_request_set *set)
{
	time64_t now = ktime_get_real_seconds();
	int timeout = 0;
	struct ptlrpc_request *req;
	time64_t deadline;

	ENTRY;
	list_for_each_entry(req, &set->set_requests, rq_set_chain) {
		/* Request in-flight? */
		if (!(((req->rq_phase == RQ_PHASE_RPC) && !req->rq_waiting) ||
		      (req->rq_phase == RQ_PHASE_BULK) ||
		      (req->rq_phase == RQ_PHASE_NEW)))
			continue;

		/* Already timed out. */
		if (req->rq_timedout)
			continue;

		/* Waiting for ctx. */
		if (req->rq_wait_ctx)
			continue;

		if (req->rq_phase == RQ_PHASE_NEW)
			deadline = req->rq_sent;
		else if (req->rq_phase == RQ_PHASE_RPC && req->rq_resend)
			deadline = req->rq_sent;
		else
			deadline = req->rq_sent + req->rq_timeout;

		if (deadline <= now)    /* actually expired already */
			timeout = 1;    /* ASAP */
		else if (timeout == 0 || timeout > deadline - now)
			timeout = deadline - now;
	}
	RETURN(timeout);
}

/**
 * ptlrpc_set_wait() - Send all unset request
 * @env: execution environment
 * @set: ptlrpc_request_set all request in a set
 *
 * Send all unset request from the set and then wait untill all
 * requests in the set complete (either get a reply, timeout, get an
 * error or otherwise be interrupted).
 *
 * Returns 0 on success or error code otherwise.
 */
int ptlrpc_set_wait(const struct lu_env *env, struct ptlrpc_request_set *set)
{
	struct ptlrpc_request *req;
	sigset_t oldset, newset;
	time64_t timeout;
	int rc;

	ENTRY;
	if (set->set_producer)
		(void)ptlrpc_set_producer(set);
	else
		list_for_each_entry(req, &set->set_requests, rq_set_chain) {
			if (req->rq_phase == RQ_PHASE_NEW)
				(void)ptlrpc_send_new_req(req);
		}

	if (list_empty(&set->set_requests))
		RETURN(0);

	do {
		DEFINE_WAIT_FUNC(wait, woken_wake_function);
		long remaining;
		unsigned long allow = 0;
		int state = TASK_IDLE;

		rc = 0;
		timeout = ptlrpc_set_next_timeout(set);
		remaining = cfs_time_seconds(timeout ? timeout : 1);

		/*
		 * wait until all complete, interrupted, or an in-flight
		 * req times out
		 */
		CDEBUG(D_RPCTRACE, "set %p going to sleep for %lld seconds\n",
		       set, timeout);

		add_wait_queue(&set->set_waitq, &wait);
		if ((timeout == 0 && !signal_pending(current)) ||
		    set->set_allow_intr) {
			state = TASK_INTERRUPTIBLE;
			allow = LUSTRE_FATAL_SIGS;
		}
		/* block until ready or timeout occurs */
		do {
			if (ptlrpc_check_set(NULL, set))
				break;
			if (allow) {
				siginitsetinv(&newset, allow);
				sigprocmask(SIG_BLOCK, &newset, &oldset);
			}
			remaining = wait_woken(&wait, state, remaining);
			if (allow) {
				if (signal_pending(current))
					remaining = -EINTR;
				sigprocmask(SIG_SETMASK, &oldset, NULL);
			}
		} while (remaining > 0);
		/*
		 * wait_woken* returns the result from schedule_timeout() which
		 * is always a positive number, or 0 on timeout.
		 */
		if (remaining == 0) {
			rc = -ETIMEDOUT;
			ptlrpc_expired_set(set);
		} else if (remaining < 0) {
			rc = -EINTR;
			ptlrpc_interrupted_set(set);
		}
		remove_wait_queue(&set->set_waitq, &wait);

		/*
		 * -EINTR => all requests have been flagged rq_intr so next
		 * check completes.
		 * -ETIMEDOUT => someone timed out.  When all reqs have
		 * timed out, signals are enabled allowing completion with
		 * EINTR.
		 * I don't really care if we go once more round the loop in
		 * the error cases -eeb.
		 */
		if (rc == 0 && atomic_read(&set->set_remaining) == 0) {
			list_for_each_entry(req, &set->set_requests,
					    rq_set_chain) {
				spin_lock(&req->rq_lock);
				req->rq_invalid_rqset = 1;
				spin_unlock(&req->rq_lock);
			}
		}
	} while (rc != 0 || atomic_read(&set->set_remaining) != 0);

	LASSERT(atomic_read(&set->set_remaining) == 0);

	rc = set->set_rc; /* rq_status of already freed requests if any */
	list_for_each_entry(req, &set->set_requests, rq_set_chain) {
		LASSERT(req->rq_phase == RQ_PHASE_COMPLETE);
		if (req->rq_status != 0)
			rc = req->rq_status;
	}

	RETURN(rc);
}
EXPORT_SYMBOL(ptlrpc_set_wait);

/*
 * Helper fuction for request freeing.
 * Called when request count reached zero and request needs to be freed.
 * Removes request from all sorts of sending/replay lists it might be on,
 * frees network buffers if any are present.
 * If \a locked is set, that means caller is already holding import imp_lock
 * and so we no longer need to reobtain it (for certain lists manipulations)
 */
static void __ptlrpc_free_req(struct ptlrpc_request *request, int locked)
{
	ENTRY;

	if (!request)
		RETURN_EXIT;

	LASSERT(!request->rq_srv_req);
	LASSERT(request->rq_export == NULL);
	LASSERTF(!request->rq_receiving_reply, "req %px\n", request);
	LASSERTF(list_empty(&request->rq_list), "req %px\n", request);
	LASSERTF(list_empty(&request->rq_set_chain), "req %px\n", request);
	LASSERTF(!request->rq_replay, "req %px\n", request);

	req_capsule_fini(&request->rq_pill);

	/*
	 * We must take it off the imp_replay_list first.  Otherwise, we'll set
	 * request->rq_reqmsg to NULL while osc_close is dereferencing it.
	 */
	if (request->rq_import) {
		if (!locked)
			spin_lock(&request->rq_import->imp_lock);
		list_del_init(&request->rq_replay_list);
		list_del_init(&request->rq_unreplied_list);
		if (!locked)
			spin_unlock(&request->rq_import->imp_lock);
	}
	LASSERTF(list_empty(&request->rq_replay_list), "req %px\n", request);

	if (atomic_read(&request->rq_refcount) != 0) {
		DEBUG_REQ(D_ERROR, request,
			  "freeing request with nonzero refcount");
		LBUG();
	}

	if (request->rq_repbuf)
		sptlrpc_cli_free_repbuf(request);

	if (request->rq_import) {
		LASSERT(atomic_read(&request->rq_import->imp_reqs) > 0);
		atomic_dec(&request->rq_import->imp_reqs);
		class_import_put(request->rq_import);
		request->rq_import = NULL;
	}
	if (request->rq_bulk)
		ptlrpc_free_bulk(request->rq_bulk);

	if (request->rq_reqbuf || request->rq_clrbuf)
		sptlrpc_cli_free_reqbuf(request);

	if (request->rq_cli_ctx)
		sptlrpc_req_put_ctx(request, !locked);

	if (request->rq_pool)
		__ptlrpc_free_req_to_pool(request);
	else
		ptlrpc_request_cache_free(request);
	EXIT;
}

/**
 * __ptlrpc_req_put() - Drops one reference count for request @request.
 * @request: Lustre request(RPC)
 * @locked: set indicates that caller holds import imp_lock.
 *
 * Frees the request whe reference count reaches zero.
 *
 * Return:
 * * %1 the request is freed
 * * %0 some others still hold references on the request
 */
static int __ptlrpc_req_put(struct ptlrpc_request *request, int locked)
{
	int count;

	ENTRY;
	if (!request)
		RETURN(1);

	LASSERT(request != LP_POISON);
	LASSERT(request->rq_reqmsg != LP_POISON);

	DEBUG_REQ(D_INFO, request, "refcount now %u",
		  atomic_read(&request->rq_refcount) - 1);

	spin_lock(&request->rq_lock);
	count = atomic_dec_return(&request->rq_refcount);
	LASSERTF(count >= 0, "Invalid ref count %d\n", count);

	/*
	 * For open RPC, the client does not know the EA size (LOV, ACL, and
	 * so on) before replied, then the client has to reserve very large
	 * reply buffer. Such buffer will not be released until the RPC freed.
	 * Since The open RPC is replayable, we need to keep it in the replay
	 * list until close. If there are a lot of files opened concurrently,
	 * then the client may be OOM.
	 *
	 * If fact, it is unnecessary to keep reply buffer for open replay,
	 * related EAs have already been saved via mdc_save_lovea() before
	 * coming here. So it is safe to free the reply buffer some earlier
	 * before releasing the RPC to avoid client OOM. LU-9514
	 */
	if (count == 1 && request->rq_early_free_repbuf && request->rq_repbuf) {
		spin_lock(&request->rq_early_free_lock);
		sptlrpc_cli_free_repbuf(request);
		request->rq_repbuf = NULL;
		request->rq_repbuf_len = 0;
		request->rq_repdata = NULL;
		request->rq_reqdata_len = 0;
		spin_unlock(&request->rq_early_free_lock);
	}
	spin_unlock(&request->rq_lock);

	if (!count)
		__ptlrpc_free_req(request, locked);

	RETURN(!count);
}

/*
 * Drop one request reference. Must be called with import imp_lock held.
 * When reference count drops to zero, request is freed.
 */
void ptlrpc_req_put_with_imp_lock(struct ptlrpc_request *request)
{
	assert_spin_locked(&request->rq_import->imp_lock);
	(void)__ptlrpc_req_put(request, 1);
}

/**
 * ptlrpc_req_put() - Drops one reference count for a request.
 * @request: Request to drop reference
 */
void ptlrpc_req_put(struct ptlrpc_request *request)
{
	__ptlrpc_req_put(request, 0);
}
EXPORT_SYMBOL(ptlrpc_req_put);


/**
 * ptlrpc_req_xid() - Returns XID of a @request
 * @request: return XID for this request
 *
 * Returns xid of a @request
 */
__u64 ptlrpc_req_xid(struct ptlrpc_request *request)
{
	return request->rq_xid;
}
EXPORT_SYMBOL(ptlrpc_req_xid);

/**
 * ptlrpc_unregister_reply() - Disengage the client's reply buffer from the
 * network
 * @request: request to unregister
 * @async: If true, do not wait for unregister to finish
 *
 * Disengage the client's reply buffer from the network.
 * NB does _NOT_ unregister any client-side bulk.
 * IDEMPOTENT, but _not_ safe against concurrent callers.
 * The request owner (i.e. the thread doing the I/O) must call...
 *
 * Returns 0 on success or 1 if unregistering cannot be made.
 */
static int ptlrpc_unregister_reply(struct ptlrpc_request *request, int async)
{
	/*
	 * Might sleep.
	 */
	LASSERT(!in_interrupt());

	/* Let's setup deadline for reply unlink. */
	if (CFS_FAIL_CHECK(OBD_FAIL_PTLRPC_LONG_REPL_UNLINK) &&
	    async && request->rq_reply_deadline == 0 && cfs_fail_val == 0)
		request->rq_reply_deadline = ktime_get_real_seconds() +
					     PTLRPC_REQ_LONG_UNLINK;

	/*
	 * Nothing left to do.
	 */
	if (!ptlrpc_client_recv_or_unlink(request))
		RETURN(1);

	LNetMDUnlink(request->rq_reply_md_h);

	/*
	 * Let's check it once again.
	 */
	if (!ptlrpc_client_recv_or_unlink(request))
		RETURN(1);

	/* Move to "Unregistering" phase as reply was not unlinked yet. */
	ptlrpc_rqphase_move(request, RQ_PHASE_UNREG_RPC);

	/*
	 * Do not wait for unlink to finish.
	 */
	if (async)
		RETURN(0);

	/*
	 * We have to wait_event_idle_timeout() whatever the result, to get
	 * a chance to run reply_in_callback(), and to make sure we've
	 * unlinked before returning a req to the pool.
	 */
	for (;;) {
		wait_queue_head_t *wq = (request->rq_set) ?
					&request->rq_set->set_waitq :
					&request->rq_reply_waitq;
		int seconds = PTLRPC_REQ_LONG_UNLINK;
		/*
		 * Network access will complete in finite time but the HUGE
		 * timeout lets us CWARN for visibility of sluggish NALs
		 */
		while (seconds > 0 &&
		       wait_event_idle_timeout(
			       *wq,
			       !ptlrpc_client_recv_or_unlink(request),
			       cfs_time_seconds(1)) == 0)
			seconds -= 1;
		if (seconds > 0) {
			ptlrpc_rqphase_move(request, request->rq_next_phase);
			RETURN(1);
		}

		DEBUG_REQ(D_WARNING, request,
			  "Unexpectedly long timeout receiving_reply=%d req_ulinked=%d reply_unlinked=%d",
			  request->rq_receiving_reply,
			  request->rq_req_unlinked,
			  request->rq_reply_unlinked);
	}
	RETURN(0);
}

static void ptlrpc_free_request(struct ptlrpc_request *req)
{
	spin_lock(&req->rq_lock);
	req->rq_replay = 0;
	spin_unlock(&req->rq_lock);

	if (req->rq_commit_cb)
		req->rq_commit_cb(req);
	list_del_init(&req->rq_replay_list);

	__ptlrpc_req_put(req, 1);
}

/**
 * ptlrpc_request_committed() - Commit request and free
 * @req: request to be committed
 * @force: @req should be forced committed (Not check trans number)
 *
 * The request is committed and dropped from the replay list of its import
 */
void ptlrpc_request_committed(struct ptlrpc_request *req, int force)
{
	struct obd_import *imp = req->rq_import;

	spin_lock(&imp->imp_lock);
	if (list_empty(&req->rq_replay_list)) {
		spin_unlock(&imp->imp_lock);
		return;
	}

	if (force || req->rq_transno <= imp->imp_peer_committed_transno) {
		if (imp->imp_replay_cursor == &req->rq_replay_list)
			imp->imp_replay_cursor = req->rq_replay_list.next;
		ptlrpc_free_request(req);
	}

	spin_unlock(&imp->imp_lock);
}
EXPORT_SYMBOL(ptlrpc_request_committed);

/**
 * ptlrpc_free_committed() - Iterates through replay_list on import and prunes
 * @imp: pointer to obd_import (import where replay list is being processed)
 *
 * Iterates through replay_list on import and prunes all requests have transno
 * smaller than last_committed for the import and don't have rq_replay set.
 * Since requests are sorted in transno order, stops when meeting first
 * transno bigger than last_committed.
 *
 * Note: caller must hold imp->imp_lock
 */
void ptlrpc_free_committed(struct obd_import *imp)
{
	struct ptlrpc_request *req, *saved;
	struct ptlrpc_request *last_req = NULL; /* temporary fire escape */
	bool skip_committed_list = true;
	unsigned int replay_scanned = 0, replay_freed = 0;
	unsigned int commit_scanned = 0, commit_freed = 0;
	unsigned int debug_level = D_INFO;
	__u64 peer_committed_transno;
	int imp_generation;
	time64_t start, now;

	ENTRY;
	LASSERT(imp != NULL);
	assert_spin_locked(&imp->imp_lock);

	start = ktime_get_seconds();
	/* save these here, we can potentially drop imp_lock after checking */
	peer_committed_transno = imp->imp_peer_committed_transno;
	imp_generation = imp->imp_generation;

	if (peer_committed_transno == imp->imp_last_transno_checked &&
	    imp_generation == imp->imp_last_generation_checked) {
		CDEBUG(D_INFO, "%s: skip recheck: last_committed %llu\n",
		       imp->imp_obd->obd_name, peer_committed_transno);
		RETURN_EXIT;
	}
	CDEBUG(D_RPCTRACE, "%s: committing for last_committed %llu gen %d\n",
	       imp->imp_obd->obd_name, peer_committed_transno, imp_generation);

	if (imp_generation != imp->imp_last_generation_checked ||
	    imp->imp_last_transno_checked == 0)
		skip_committed_list = false;
	/* maybe drop imp_lock here, if another lock protected the lists */

	list_for_each_entry_safe(req, saved, &imp->imp_replay_list,
				 rq_replay_list) {
		/* XXX ok to remove when 1357 resolved - rread 05/29/03  */
		LASSERT(req != last_req);
		last_req = req;

		if (req->rq_transno == 0) {
			DEBUG_REQ(D_EMERG, req, "zero transno during replay");
			LBUG();
		}

		/* If other threads are waiting on imp_lock, stop processing
		 * in this thread. Another thread can finish remaining work.
		 * This may happen if there are huge numbers of open files
		 * that are closed suddenly or evicted, or if the server
		 * commit interval is very high vs. RPC rate.
		 */
		if (++replay_scanned % 2048 == 0) {
			now = ktime_get_seconds();
			if (now > start + 5)
				debug_level = D_WARNING;

			if ((replay_freed > 128 && now > start + 3) &&
			    atomic_read(&imp->imp_waiting)) {
				if (debug_level == D_INFO)
					debug_level = D_RPCTRACE;
				break;
			}
		}

		if (req->rq_import_generation < imp_generation) {
			DEBUG_REQ(D_RPCTRACE, req, "free request with old gen");
			GOTO(free_req, 0);
		}

		/* not yet committed */
		if (req->rq_transno > peer_committed_transno) {
			DEBUG_REQ(D_RPCTRACE, req, "stopping search");
			break;
		}

		if (req->rq_replay) {
			DEBUG_REQ(D_RPCTRACE, req, "keeping (FL_REPLAY)");
			list_move_tail(&req->rq_replay_list,
				       &imp->imp_committed_list);
			continue;
		}

		DEBUG_REQ(D_INFO, req, "commit (last_committed %llu)",
			  peer_committed_transno);
free_req:
		replay_freed++;
		ptlrpc_free_request(req);
	}

	if (skip_committed_list)
		GOTO(out, 0);

	list_for_each_entry_safe(req, saved, &imp->imp_committed_list,
				 rq_replay_list) {
		LASSERT(req->rq_transno != 0);

		/* If other threads are waiting on imp_lock, stop processing
		 * in this thread. Another thread can finish remaining work. */
		if (++commit_scanned % 2048 == 0) {
			now = ktime_get_seconds();
			if (now > start + 6)
				debug_level = D_WARNING;

			if ((commit_freed > 128 && now > start + 4) &&
			    atomic_read(&imp->imp_waiting)) {
				if (debug_level == D_INFO)
					debug_level = D_RPCTRACE;
				break;
			}
		}

		if (req->rq_import_generation < imp_generation ||
		    !req->rq_replay) {
			DEBUG_REQ(D_RPCTRACE, req, "free %s open request",
				  req->rq_import_generation <
				  imp_generation ? "stale" : "closed");

			if (imp->imp_replay_cursor == &req->rq_replay_list)
				imp->imp_replay_cursor =
					req->rq_replay_list.next;

			commit_freed++;
			ptlrpc_free_request(req);
		}
	}
out:
	/* if full lists processed without interruption, avoid next scan */
	if (debug_level == D_INFO) {
		imp->imp_last_transno_checked = peer_committed_transno;
		imp->imp_last_generation_checked = imp_generation;
	}

	CDEBUG_LIMIT(debug_level,
		     "%s: %s: skip=%u replay=%u/%u committed=%u/%u\n",
		     imp->imp_obd->obd_name,
		     debug_level == D_INFO ? "normal" : "overloaded",
		     skip_committed_list, replay_freed, replay_scanned,
		     commit_freed, commit_scanned);
	EXIT;
}

/*
 * Schedule previously sent request for resend.
 * For bulk requests we assign new xid (to avoid problems with
 * lost replies and therefore several transfers landing into same buffer
 * from different sending attempts).
 */
void ptlrpc_resend_req(struct ptlrpc_request *req)
{
	DEBUG_REQ(D_HA, req, "going to resend");
	spin_lock(&req->rq_lock);

	/*
	 * Request got reply but linked to the import list still.
	 * Let ptlrpc_check_set() process it.
	 */
	if (ptlrpc_client_replied(req)) {
		spin_unlock(&req->rq_lock);
		DEBUG_REQ(D_HA, req, "it has reply, so skip it");
		return;
	}

	req->rq_status = -EAGAIN;

	req->rq_resend = 1;
	req->rq_net_err = 0;
	req->rq_timedout = 0;

	ptlrpc_client_wake_req(req);
	spin_unlock(&req->rq_lock);
}

/* XXX: this function and rq_status are currently unused */
void ptlrpc_restart_req(struct ptlrpc_request *req)
{
	DEBUG_REQ(D_HA, req, "restarting (possibly-)completed request");
	req->rq_status = -ERESTARTSYS;

	spin_lock(&req->rq_lock);
	req->rq_restart = 1;
	req->rq_timedout = 0;
	ptlrpc_client_wake_req(req);
	spin_unlock(&req->rq_lock);
}

/*
 * Grab additional reference on a request \a req
 */
struct ptlrpc_request *ptlrpc_request_addref(struct ptlrpc_request *req)
{
	ENTRY;
	atomic_inc(&req->rq_refcount);
	RETURN(req);
}
EXPORT_SYMBOL(ptlrpc_request_addref);

/*
 * Add a request to import replay_list.
 * Must be called under imp_lock
 */
void ptlrpc_retain_replayable_request(struct ptlrpc_request *req,
				      struct obd_import *imp)
{
	struct ptlrpc_request *iter;

	assert_spin_locked(&imp->imp_lock);

	if (req->rq_transno == 0) {
		DEBUG_REQ(D_EMERG, req, "saving request with zero transno");
		LBUG();
	}

	/*
	 * clear this for new requests that were resent as well
	 * as resent replayed requests.
	 */
	lustre_msg_clear_flags(req->rq_reqmsg, MSG_RESENT);

	/* don't re-add requests that have been replayed */
	if (!list_empty(&req->rq_replay_list))
		return;

	lustre_msg_add_flags(req->rq_reqmsg, MSG_REPLAY);

	spin_lock(&req->rq_lock);
	req->rq_resend = 0;
	spin_unlock(&req->rq_lock);

	LASSERT(imp->imp_replayable);
	/* Balanced in ptlrpc_free_committed, usually. */
	ptlrpc_request_addref(req);
	list_for_each_entry_reverse(iter, &imp->imp_replay_list,
				    rq_replay_list) {
		/*
		 * We may have duplicate transnos if we create and then
		 * open a file, or for closes retained if to match creating
		 * opens, so use req->rq_xid as a secondary key.
		 * (See bugs 684, 685, and 428.)
		 * XXX no longer needed, but all opens need transnos!
		 */
		if (iter->rq_transno > req->rq_transno)
			continue;

		if (iter->rq_transno == req->rq_transno) {
			LASSERT(iter->rq_xid != req->rq_xid);
			if (iter->rq_xid > req->rq_xid)
				continue;
		}

		list_add(&req->rq_replay_list, &iter->rq_replay_list);
		return;
	}

	list_add(&req->rq_replay_list, &imp->imp_replay_list);
}

/**
 * ptlrpc_queue_wait() - Send request and wait until it completes.
 * @req: request to be sent and waited
 *
 * Return 0 on success or error code otherwise.
 */
int ptlrpc_queue_wait(struct ptlrpc_request *req)
{
	struct ptlrpc_request_set *set;
	int rc;

	ENTRY;
	LASSERT(req->rq_set == NULL);
	LASSERT(!req->rq_receiving_reply);

	set = ptlrpc_prep_set();
	if (!set) {
		CERROR("cannot allocate ptlrpc set: rc = %d\n", -ENOMEM);
		RETURN(-ENOMEM);
	}

	/* for distributed debugging */
	lustre_msg_set_status(req->rq_reqmsg, current->pid);

	/* add a ref for the set (see comment in ptlrpc_set_add_req) */
	ptlrpc_request_addref(req);
	ptlrpc_set_add_req(set, req);
	rc = ptlrpc_set_wait(NULL, set);
	ptlrpc_set_destroy(set);

	RETURN(rc);
}
EXPORT_SYMBOL(ptlrpc_queue_wait);

/*
 * Callback used for replayed requests reply processing.
 * In case of successful reply calls registered request replay callback.
 * In case of error restart replay process.
 */
static int ptlrpc_replay_interpret(const struct lu_env *env,
				   struct ptlrpc_request *req,
				   void *args, int rc)
{
	struct ptlrpc_replay_async_args *aa = args;
	struct obd_import *imp = req->rq_import;

	ENTRY;
	atomic_dec(&imp->imp_replay_inflight);

	/*
	 * Note: if it is bulk replay (MDS-MDS replay), then even if
	 * server got the request, but bulk transfer timeout, let's
	 * replay the bulk req again
	 */
	if (!ptlrpc_client_replied(req) ||
	    (req->rq_bulk &&
	     lustre_msg_get_status(req->rq_repmsg) == -ETIMEDOUT)) {
		DEBUG_REQ(D_ERROR, req, "request replay timed out");
		GOTO(out, rc = -ETIMEDOUT);
	}

	if (lustre_msg_get_type(req->rq_repmsg) == PTL_RPC_MSG_ERR &&
	    (lustre_msg_get_status(req->rq_repmsg) == -ENOTCONN ||
	    lustre_msg_get_status(req->rq_repmsg) == -ENODEV))
		GOTO(out, rc = lustre_msg_get_status(req->rq_repmsg));

	/** VBR: check version failure */
	if (lustre_msg_get_status(req->rq_repmsg) == -EOVERFLOW) {
		/** replay was failed due to version mismatch */
		DEBUG_REQ(D_WARNING, req, "Version mismatch during replay");
		spin_lock(&imp->imp_lock);
		imp->imp_vbr_failed = 1;
		spin_unlock(&imp->imp_lock);
		lustre_msg_set_status(req->rq_repmsg, aa->praa_old_status);
	} else {
		/** The transno had better not change over replay. */
		LASSERTF(lustre_msg_get_transno(req->rq_reqmsg) ==
			 lustre_msg_get_transno(req->rq_repmsg) ||
			 lustre_msg_get_transno(req->rq_repmsg) == 0,
			 "%#llx/%#llx\n",
			 lustre_msg_get_transno(req->rq_reqmsg),
			 lustre_msg_get_transno(req->rq_repmsg));
	}

	spin_lock(&imp->imp_lock);
	imp->imp_last_replay_transno = lustre_msg_get_transno(req->rq_reqmsg);
	spin_unlock(&imp->imp_lock);
	LASSERT(imp->imp_last_replay_transno);

	/* transaction number shouldn't be bigger than the latest replayed */
	if (req->rq_transno > lustre_msg_get_transno(req->rq_reqmsg)) {
		DEBUG_REQ(D_ERROR, req,
			  "Reported transno=%llu is bigger than replayed=%llu",
			  req->rq_transno,
			  lustre_msg_get_transno(req->rq_reqmsg));
		GOTO(out, rc = -EINVAL);
	}

	DEBUG_REQ(D_HA, req, "got reply");

	/* let the callback do fixups, possibly including in the request */
	if (req->rq_replay_cb)
		req->rq_replay_cb(req);

	if (ptlrpc_client_replied(req) &&
	    lustre_msg_get_status(req->rq_repmsg) != aa->praa_old_status) {
		DEBUG_REQ(D_ERROR, req, "status %d, old was %d",
			  lustre_msg_get_status(req->rq_repmsg),
			  aa->praa_old_status);

		/*
		 * Note: If the replay fails for MDT-MDT recovery, let's
		 * abort all of the following requests in the replay
		 * and sending list, because MDT-MDT update requests
		 * are dependent on each other, see LU-7039
		 */
		if (imp->imp_connect_flags_orig & OBD_CONNECT_MDS_MDS) {
			struct ptlrpc_request *free_req;
			struct ptlrpc_request *tmp;

			spin_lock(&imp->imp_lock);
			list_for_each_entry_safe(free_req, tmp,
						 &imp->imp_replay_list,
						 rq_replay_list) {
				ptlrpc_free_request(free_req);
			}

			list_for_each_entry_safe(free_req, tmp,
						 &imp->imp_committed_list,
						 rq_replay_list) {
				ptlrpc_free_request(free_req);
			}

			list_for_each_entry_safe(free_req, tmp,
						 &imp->imp_delayed_list,
						 rq_list) {
				spin_lock(&free_req->rq_lock);
				free_req->rq_err = 1;
				free_req->rq_status = -EIO;
				ptlrpc_client_wake_req(free_req);
				spin_unlock(&free_req->rq_lock);
			}

			list_for_each_entry_safe(free_req, tmp,
						 &imp->imp_sending_list,
						 rq_list) {
				spin_lock(&free_req->rq_lock);
				free_req->rq_err = 1;
				free_req->rq_status = -EIO;
				ptlrpc_client_wake_req(free_req);
				spin_unlock(&free_req->rq_lock);
			}
			spin_unlock(&imp->imp_lock);
		}
	} else {
		/* Put it back for re-replay. */
		lustre_msg_set_status(req->rq_repmsg, aa->praa_old_status);
	}

	/*
	 * Errors while replay can set transno to 0, but
	 * imp_last_replay_transno shouldn't be set to 0 anyway
	 */
	if (req->rq_transno == 0)
		CERROR("Transno is 0 during replay!\n");

	/* continue with recovery */
	rc = ptlrpc_import_recovery_state_machine(imp);
 out:
	req->rq_send_state = aa->praa_old_state;

	if (rc != 0)
		/* this replay failed, so restart recovery */
		ptlrpc_connect_import(imp);

	RETURN(rc);
}

/**
 * ptlrpc_replay_req() - Prepares and queues request for replay. Adds it to
 * ptlrpcd queue for actual sending.
 * @req: request to replay
 *
 * Returns 0 on success.
 */
int ptlrpc_replay_req(struct ptlrpc_request *req)
{
	struct ptlrpc_replay_async_args *aa;

	ENTRY;

	LASSERT(req->rq_import->imp_state == LUSTRE_IMP_REPLAY);

	CFS_FAIL_TIMEOUT(OBD_FAIL_PTLRPC_REPLAY_PAUSE, cfs_fail_val);

	aa = ptlrpc_req_async_args(aa, req);
	memset(aa, 0, sizeof(*aa));

	/* Prepare request to be resent with ptlrpcd */
	aa->praa_old_state = req->rq_send_state;
	req->rq_send_state = LUSTRE_IMP_REPLAY;
	req->rq_phase = RQ_PHASE_NEW;
	req->rq_next_phase = RQ_PHASE_UNDEFINED;
	if (req->rq_repmsg)
		aa->praa_old_status = lustre_msg_get_status(req->rq_repmsg);
	req->rq_status = 0;
	req->rq_interpret_reply = ptlrpc_replay_interpret;
	/* Readjust the timeout for current conditions */
	ptlrpc_at_set_req_timeout(req);

	/* Tell server net_latency to calculate how long to wait for reply. */
	lustre_msg_set_service_timeout(req->rq_reqmsg,
				       ptlrpc_at_get_net_latency(req));
	DEBUG_REQ(D_HA, req, "REPLAY");

	atomic_inc(&req->rq_import->imp_replay_inflight);
	spin_lock(&req->rq_lock);
	req->rq_early_free_repbuf = 0;
	spin_unlock(&req->rq_lock);
	ptlrpc_request_addref(req); /* ptlrpcd needs a ref */

	ptlrpcd_add_req(req);
	RETURN(0);
}

/**
 * ptlrpc_abort_inflight() - Aborts all in-flight request on import.
 * @imp: import where request will be aborted
 *
 * Aborts all in-flight request on import @imp sending and delayed lists
 */
void ptlrpc_abort_inflight(struct obd_import *imp)
{
	struct ptlrpc_request *req;
	ENTRY;

	/*
	 * Make sure that no new requests get processed for this import.
	 * ptlrpc_{queue,set}_wait must (and does) hold imp_lock while testing
	 * this flag and then putting requests on sending_list or delayed_list.
	 */
	assert_spin_locked(&imp->imp_lock);

	/*
	 * XXX locking?  Maybe we should remove each request with the list
	 * locked?  Also, how do we know if the requests on the list are
	 * being freed at this time?
	 */
	list_for_each_entry(req, &imp->imp_sending_list, rq_list) {
		DEBUG_REQ(D_RPCTRACE, req, "inflight");

		spin_lock(&req->rq_lock);
		if (req->rq_import_generation < imp->imp_generation) {
			req->rq_err = 1;
			req->rq_status = -EIO;
			ptlrpc_client_wake_req(req);
		}
		spin_unlock(&req->rq_lock);
	}

	list_for_each_entry(req, &imp->imp_delayed_list, rq_list) {
		DEBUG_REQ(D_RPCTRACE, req, "aborting waiting req");

		spin_lock(&req->rq_lock);
		if (req->rq_import_generation < imp->imp_generation) {
			req->rq_err = 1;
			req->rq_status = -EIO;
			ptlrpc_client_wake_req(req);
		}
		spin_unlock(&req->rq_lock);
	}

	/*
	 * Last chance to free reqs left on the replay list, but we
	 * will still leak reqs that haven't committed.
	 */
	if (imp->imp_replayable)
		ptlrpc_free_committed(imp);

	EXIT;
}

/**
 * ptlrpc_abort_set() - Abort all uncompleted requests in request set @set
 * @set: ptlrpc_request_set to be aborted
 */
void ptlrpc_abort_set(struct ptlrpc_request_set *set)
{
	struct ptlrpc_request *req;

	LASSERT(set != NULL);

	list_for_each_entry(req, &set->set_requests, rq_set_chain) {
		spin_lock(&req->rq_lock);
		if (req->rq_phase != RQ_PHASE_RPC) {
			spin_unlock(&req->rq_lock);
			continue;
		}

		req->rq_err = 1;
		req->rq_status = -EINTR;
		ptlrpc_client_wake_req(req);
		spin_unlock(&req->rq_lock);
	}
}

/*
 * Initialize the XID for the node.  This is common among all requests on
 * this node, and only requires the property that it is monotonically
 * increasing.  It does not need to be sequential.  Since this is also used
 * as the RDMA match bits, it is important that a single client NOT have
 * the same match bits for two different in-flight requests, hence we do
 * NOT want to have an XID per target or similar.
 *
 * To avoid an unlikely collision between match bits after a client reboot
 * (which would deliver old data into the wrong RDMA buffer) initialize
 * the XID based on the current time, assuming a maximum RPC rate of 1M RPC/s.
 * If the time is clearly incorrect, we instead use a 62-bit random number.
 * In the worst case the random number will overflow 1M RPCs per second in
 * 9133 years, or permutations thereof.
 */
#define YEAR_2004 (1ULL << 30)
void ptlrpc_init_xid(void)
{
	time64_t now = ktime_get_real_seconds();
	u64 xid;

	if (now < YEAR_2004) {
		get_random_bytes(&xid, sizeof(xid));
		xid >>= 2;
		xid |= (1ULL << 61);
	} else {
		xid = (u64)now << 20;
	}

	/* Need to always be aligned to a power-of-two for mutli-bulk BRW */
	BUILD_BUG_ON((PTLRPC_BULK_OPS_COUNT & (PTLRPC_BULK_OPS_COUNT - 1)) !=
		     0);
	xid &= PTLRPC_BULK_OPS_MASK;
	atomic64_set(&ptlrpc_last_xid, xid);
}

/*
 * Increase xid and returns resulting new value to the caller.
 *
 * Multi-bulk BRW RPCs consume multiple XIDs for each bulk transfer, starting
 * at the returned xid, up to xid + PTLRPC_BULK_OPS_COUNT - 1. The BRW RPC
 * itself uses the last bulk xid needed, so the server can determine the
 * the number of bulk transfers from the RPC XID and a bitmask.  The starting
 * xid must align to a power-of-two value.
 *
 * This is assumed to be true due to the initial ptlrpc_last_xid
 * value also being initialized to a power-of-two value. LU-1431
 */
__u64 ptlrpc_next_xid(void)
{
	return atomic64_add_return(PTLRPC_BULK_OPS_COUNT, &ptlrpc_last_xid);
}

/*
 * If request has a new allocated XID (new request or EINPROGRESS resend),
 * use this XID as matchbits of bulk, otherwise allocate a new matchbits for
 * request to ensure previous bulk fails and avoid problems with lost replies
 * and therefore several transfers landing into the same buffer from different
 * sending attempts.
 * Also, to avoid previous reply landing to a different sending attempt.
 */
void ptlrpc_set_mbits(struct ptlrpc_request *req)
{
	int md_count = req->rq_bulk ? req->rq_bulk->bd_md_count : 1;

	/*
	 * Generate new matchbits for all resend requests, including
	 * resend replay.
	 */
	if (req->rq_resend) {
		__u64 old_mbits = req->rq_mbits;

		/*
		 * First time resend on -EINPROGRESS will generate new xid,
		 * so we can actually use the rq_xid as rq_mbits in such case,
		 * however, it's bit hard to distinguish such resend with a
		 * 'resend for the -EINPROGRESS resend'. To make it simple,
		 * we opt to generate mbits for all resend cases.
		 */
		if (OCD_HAS_FLAG(&req->rq_import->imp_connect_data,
				 BULK_MBITS)) {
			req->rq_mbits = ptlrpc_next_xid();
		} else {
			/*
			 * Old version transfers rq_xid to peer as
			 * matchbits.
			 */
			spin_lock(&req->rq_import->imp_lock);
			list_del_init(&req->rq_unreplied_list);
			ptlrpc_assign_next_xid_nolock(req);
			spin_unlock(&req->rq_import->imp_lock);
			req->rq_mbits = req->rq_xid;
		}
		CDEBUG(D_HA, "resend with new mbits old x%llu new x%llu\n",
		       old_mbits, req->rq_mbits);
	} else if (!(lustre_msg_get_flags(req->rq_reqmsg) & MSG_REPLAY)) {
		/* Request being sent first time, use xid as matchbits. */
		if (OCD_HAS_FLAG(&req->rq_import->imp_connect_data,
				 BULK_MBITS) || req->rq_mbits == 0)
		{
			req->rq_mbits = req->rq_xid;
		} else {
			req->rq_mbits -= md_count - 1;
		}
	} else {
		/*
		 * Replay request, xid and matchbits have already been
		 * correctly assigned.
		 */
		return;
	}

	/*
	 * For multi-bulk RPCs, rq_mbits is the last mbits needed for bulks so
	 * that server can infer the number of bulks that were prepared,
	 * see LU-1431
	 */
	req->rq_mbits += md_count - 1;

	/*
	 * Set rq_xid as rq_mbits to indicate the final bulk for the old
	 * server which does not support OBD_CONNECT_BULK_MBITS. LU-6808.
	 *
	 * It's ok to directly set the rq_xid here, since this xid bump
	 * won't affect the request position in unreplied list.
	 */
	if (!OCD_HAS_FLAG(&req->rq_import->imp_connect_data, BULK_MBITS))
		req->rq_xid = req->rq_mbits;
}

/**
 * ptlrpc_sample_next_xid() - Get a glimpse at what next xid value might have
 * been.
 *
 * Returns possible next xid.
 */
__u64 ptlrpc_sample_next_xid(void)
{
	return atomic64_read(&ptlrpc_last_xid) + PTLRPC_BULK_OPS_COUNT;
}
EXPORT_SYMBOL(ptlrpc_sample_next_xid);

/**
 * ptlrpc_reqset_free() - Release memory allocated for ptlrpc_request_set
 * @kref: kref when dropped below 1
 *
 * Used as a kref release callback, when the last user of ptlrpc_request_set
 * is released.
 */
void ptlrpc_reqset_free(struct kref *kref)
{
	struct ptlrpc_request_set *set = container_of(kref,
						      struct ptlrpc_request_set,
						      set_refcount);
	OBD_FREE_PTR(set);
}
