Whamcloud - gitweb
LU-769 ptlrpc: Do not miss pending signals in ptlrpc_set wait
[fs/lustre-release.git] / lustre / ptlrpc / client.c
index a26f440..e9979df 100644 (file)
  * GPL HEADER END
  */
 /*
- * Copyright  2008 Sun Microsystems, Inc. All rights reserved
+ * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
+ *
+ * Copyright (c) 2011 Whamcloud, Inc.
+ *
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
  * Lustre is a trademark of Sun Microsystems, Inc.
  */
 
+/** Implementation of client-side PortalRPC interfaces */
+
 #define DEBUG_SUBSYSTEM S_RPC
 #ifndef __KERNEL__
 #include <errno.h>
@@ -50,6 +55,9 @@
 
 #include "ptlrpc_internal.h"
 
+/**
+ * Initialize passed in client structure \a cl.
+ */
 void ptlrpc_init_client(int req_portal, int rep_portal, char *name,
                         struct ptlrpc_client *cl)
 {
@@ -58,6 +66,9 @@ void ptlrpc_init_client(int req_portal, int rep_portal, char *name,
         cl->cli_name           = name;
 }
 
+/**
+ * Return PortalRPC connection for remore uud \a uuid
+ */
 struct ptlrpc_connection *ptlrpc_uuid_to_connection(struct obd_uuid *uuid)
 {
         struct ptlrpc_connection *c;
@@ -67,7 +78,7 @@ struct ptlrpc_connection *ptlrpc_uuid_to_connection(struct obd_uuid *uuid)
 
         err = ptlrpc_uuid_to_peer(uuid, &peer, &self);
         if (err != 0) {
-                CERROR("cannot find peer %s!\n", uuid->uuid);
+                CNETERR("cannot find peer %s!\n", uuid->uuid);
                 return NULL;
         }
 
@@ -82,6 +93,10 @@ struct ptlrpc_connection *ptlrpc_uuid_to_connection(struct obd_uuid *uuid)
         return c;
 }
 
+/**
+ * Allocate and initialize new bulk descriptor
+ * Returns pointer to the descriptor or NULL on error.
+ */
 static inline struct ptlrpc_bulk_desc *new_bulk(int npages, int type, int portal)
 {
         struct ptlrpc_bulk_desc *desc;
@@ -101,6 +116,13 @@ static inline struct ptlrpc_bulk_desc *new_bulk(int npages, int type, int portal
         return desc;
 }
 
+/**
+ * Prepare bulk descriptor for specified outgoing request \a req that
+ * can fit \a npages * pages. \a type is bulk type. \a portal is where
+ * the bulk to be sent. 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,
                                               int npages, int type, int portal)
 {
@@ -126,6 +148,14 @@ struct ptlrpc_bulk_desc *ptlrpc_prep_bulk_imp(struct ptlrpc_request *req,
         return desc;
 }
 
+/**
+ * Prepare bulk descriptor for specified incoming request \a req that
+ * can fit \a npages * pages. \a type is bulk type. \a portal is where
+ * the bulk to be sent. Used on server-side after request was already
+ * received.
+ * Returns pointer to newly allocatrd initialized bulk descriptor or NULL on
+ * error.
+ */
 struct ptlrpc_bulk_desc *ptlrpc_prep_bulk_exp(struct ptlrpc_request *req,
                                               int npages, int type, int portal)
 {
@@ -151,6 +181,11 @@ struct ptlrpc_bulk_desc *ptlrpc_prep_bulk_exp(struct ptlrpc_request *req,
         return desc;
 }
 
+/**
+ * Add a page \a page to the bulk descriptor \a desc.
+ * Data to transfer in the page starts at offset \a pageoffset and
+ * amount of data to transfer from the page is \a len
+ */
 void ptlrpc_prep_bulk_page(struct ptlrpc_bulk_desc *desc,
                            cfs_page_t *page, int pageoffset, int len)
 {
@@ -162,11 +197,17 @@ void ptlrpc_prep_bulk_page(struct ptlrpc_bulk_desc *desc,
 
         desc->bd_nob += len;
 
+        cfs_page_pin(page);
         ptlrpc_add_bulk_page(desc, page, pageoffset, len);
 }
 
+/**
+ * Uninitialize and free bulk descriptor \a desc.
+ * Works on bulk descriptors both from server and client side.
+ */
 void ptlrpc_free_bulk(struct ptlrpc_bulk_desc *desc)
 {
+        int i;
         ENTRY;
 
         LASSERT(desc != NULL);
@@ -181,12 +222,18 @@ void ptlrpc_free_bulk(struct ptlrpc_bulk_desc *desc)
         else
                 class_import_put(desc->bd_import);
 
+        for (i = 0; i < desc->bd_iov_count ; i++)
+                cfs_page_unpin(desc->bd_iov[i].kiov_page);
+
         OBD_FREE(desc, offsetof(struct ptlrpc_bulk_desc,
                                 bd_iov[desc->bd_max_iov]));
         EXIT;
 }
 
-/* Set server timelimit for this req */
+/**
+ * Set server timelimit for this req, i.e. how long are we willing to wait
+ * for reply before timing out this request.
+ */
 void ptlrpc_at_set_req_timeout(struct ptlrpc_request *req)
 {
         __u32 serv_est;
@@ -197,6 +244,13 @@ void ptlrpc_at_set_req_timeout(struct ptlrpc_request *req)
 
         if (AT_OFF) {
                 /* 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 {
@@ -228,7 +282,7 @@ static void ptlrpc_at_adj_service(struct ptlrpc_request *req,
         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 = at_add(&at->iat_service_estimate[idx], serv_est);
+        oldse = at_measured(&at->iat_service_estimate[idx], serv_est);
         if (oldse != 0)
                 CDEBUG(D_ADAPTTO, "The RPC service estimate for %s ptl %d "
                        "has changed from %d to %d\n",
@@ -260,7 +314,7 @@ static void ptlrpc_at_adj_net_latency(struct ptlrpc_request *req,
                       CFS_DURATION_T"\n", service_time,
                       cfs_time_sub(now, req->rq_sent));
 
-        oldnl = at_add(&at->iat_net_latency, nl);
+        oldnl = at_measured(&at->iat_net_latency, nl);
         if (oldnl != 0)
                 CDEBUG(D_ADAPTTO, "The network latency for %s (nid %s) "
                        "has changed from %d to %d\n",
@@ -290,7 +344,7 @@ static int unpack_reply(struct ptlrpc_request *req)
         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
  */
@@ -344,6 +398,10 @@ static int ptlrpc_at_recv_early_reply(struct ptlrpc_request *req)
         RETURN(rc);
 }
 
+/**
+ * Wind down request pool \a pool.
+ * Frees all requests from the pool too
+ */
 void ptlrpc_free_rq_pool(struct ptlrpc_request_pool *pool)
 {
         cfs_list_t *l, *tmp;
@@ -357,19 +415,22 @@ void ptlrpc_free_rq_pool(struct ptlrpc_request_pool *pool)
                 cfs_list_del(&req->rq_list);
                 LASSERT(req->rq_reqbuf);
                 LASSERT(req->rq_reqbuf_len == pool->prp_rq_size);
-                OBD_FREE(req->rq_reqbuf, pool->prp_rq_size);
+                OBD_FREE_LARGE(req->rq_reqbuf, pool->prp_rq_size);
                 OBD_FREE(req, sizeof(*req));
         }
         cfs_spin_unlock(&pool->prp_lock);
         OBD_FREE(pool, sizeof(*pool));
 }
 
+/**
+ * Allocates, initializes and adds \a num_rq requests to the pool \a pool
+ */
 void ptlrpc_add_rqs_to_pool(struct ptlrpc_request_pool *pool, int num_rq)
 {
         int i;
         int size = 1;
 
-        while (size < pool->prp_rq_size + SPTLRPC_MAX_PAYLOAD)
+        while (size < pool->prp_rq_size)
                 size <<= 1;
 
         LASSERTF(cfs_list_empty(&pool->prp_req_list) ||
@@ -387,7 +448,7 @@ void ptlrpc_add_rqs_to_pool(struct ptlrpc_request_pool *pool, int num_rq)
                 OBD_ALLOC(req, sizeof(struct ptlrpc_request));
                 if (!req)
                         return;
-                OBD_ALLOC_GFP(msg, size, CFS_ALLOC_STD);
+                OBD_ALLOC_LARGE(msg, size);
                 if (!msg) {
                         OBD_FREE(req, sizeof(struct ptlrpc_request));
                         return;
@@ -402,6 +463,14 @@ void ptlrpc_add_rqs_to_pool(struct ptlrpc_request_pool *pool, int num_rq)
         return;
 }
 
+/**
+ * Create and initialize new request pool with given attributes:
+ * \a num_rq - initial number of requests to create for the pool
+ * \a msgsize - maximum message size possible for requests in thid pool
+ * \a 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,
                     void (*populate_pool)(struct ptlrpc_request_pool *, int))
@@ -417,7 +486,7 @@ ptlrpc_init_rq_pool(int num_rq, int msgsize,
 
         cfs_spin_lock_init(&pool->prp_lock);
         CFS_INIT_LIST_HEAD(&pool->prp_req_list);
-        pool->prp_rq_size = msgsize;
+        pool->prp_rq_size = msgsize + SPTLRPC_MAX_PAYLOAD;
         pool->prp_populate = populate_pool;
 
         populate_pool(pool, num_rq);
@@ -430,6 +499,9 @@ ptlrpc_init_rq_pool(int num_rq, int msgsize,
         return pool;
 }
 
+/**
+ * Fetches one request from pool \a pool
+ */
 static struct ptlrpc_request *
 ptlrpc_prep_req_from_pool(struct ptlrpc_request_pool *pool)
 {
@@ -467,6 +539,9 @@ ptlrpc_prep_req_from_pool(struct ptlrpc_request_pool *pool)
         return request;
 }
 
+/**
+ * Returns freed \a request to pool.
+ */
 static void __ptlrpc_free_req_to_pool(struct ptlrpc_request *request)
 {
         struct ptlrpc_request_pool *pool = request->rq_pool;
@@ -533,6 +608,7 @@ static int __ptlrpc_request_bufs_pack(struct ptlrpc_request *request,
         CFS_INIT_LIST_HEAD(&request->rq_history_list);
         CFS_INIT_LIST_HEAD(&request->rq_exp_list);
         cfs_waitq_init(&request->rq_reply_waitq);
+        cfs_waitq_init(&request->rq_set_waitq);
         request->rq_xid = ptlrpc_next_xid();
         cfs_atomic_set(&request->rq_refcount, 1);
 
@@ -559,12 +635,22 @@ int ptlrpc_request_bufs_pack(struct ptlrpc_request *request,
 }
 EXPORT_SYMBOL(ptlrpc_request_bufs_pack);
 
+/**
+ * Pack request buffers for network transfer, performing necessary encryption
+ * steps if necessary.
+ */
 int ptlrpc_request_pack(struct ptlrpc_request *request,
                         __u32 version, int opcode)
 {
         return ptlrpc_request_bufs_pack(request, version, opcode, NULL, NULL);
 }
 
+/**
+ * Helper function to allocate new request on import \a imp
+ * and possibly using existing request from pool \a pool if provided.
+ * 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)
@@ -592,6 +678,12 @@ struct ptlrpc_request *__ptlrpc_request_alloc(struct obd_import *imp,
         return request;
 }
 
+/**
+ * Helper function for creating a request.
+ * Calls __ptlrpc_request_alloc to allocate new request sturcture and inits
+ * buffer structures according to capsule template \a 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,
@@ -608,12 +700,20 @@ ptlrpc_request_alloc_internal(struct obd_import *imp,
         return request;
 }
 
+/**
+ * Allocate new request structure for import \a imp and initialize its
+ * buffer structure according to capsule template \a format.
+ */
 struct ptlrpc_request *ptlrpc_request_alloc(struct obd_import *imp,
                                             const struct req_format *format)
 {
         return ptlrpc_request_alloc_internal(imp, NULL, format);
 }
 
+/**
+ * Allocate new request structure for import \a imp from pool \a pool and
+ * initialize its buffer structure according to capsule template \a format.
+ */
 struct ptlrpc_request *ptlrpc_request_alloc_pool(struct obd_import *imp,
                                             struct ptlrpc_request_pool * pool,
                                             const struct req_format *format)
@@ -621,6 +721,10 @@ struct ptlrpc_request *ptlrpc_request_alloc_pool(struct obd_import *imp,
         return ptlrpc_request_alloc_internal(imp, pool, format);
 }
 
+/**
+ * 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)
@@ -629,6 +733,13 @@ void ptlrpc_request_free(struct ptlrpc_request *request)
                 OBD_FREE_PTR(request);
 }
 
+/**
+ * Allocate new request for operatione \a 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 or NULL on error.
+ */
 struct ptlrpc_request *ptlrpc_request_alloc_pack(struct obd_import *imp,
                                                 const struct req_format *format,
                                                 __u32 version, int opcode)
@@ -646,6 +757,13 @@ struct ptlrpc_request *ptlrpc_request_alloc_pack(struct obd_import *imp,
         return req;
 }
 
+/**
+ * Prepare request (fetched from pool \a poolif not NULL) on import \a imp
+ * for operation \a opcode. Request would contain \a count buffers.
+ * Sizes of buffers are described in array \a lengths and buffers themselves
+ * are provided by a pointer \a bufs.
+ * Returns prepared request structure pointer or NULL on error.
+ */
 struct ptlrpc_request *
 ptlrpc_prep_req_pool(struct obd_import *imp,
                      __u32 version, int opcode,
@@ -668,6 +786,9 @@ ptlrpc_prep_req_pool(struct obd_import *imp,
         return request;
 }
 
+/**
+ * Same as ptlrpc_prep_req_pool, but without pool
+ */
 struct ptlrpc_request *
 ptlrpc_prep_req(struct obd_import *imp, __u32 version, int opcode, int count,
                 __u32 *lengths, char **bufs)
@@ -676,6 +797,13 @@ ptlrpc_prep_req(struct obd_import *imp, __u32 version, int opcode, int count,
                                     NULL);
 }
 
+/**
+ * Allocate "fake" request that would not be sent anywhere in the end.
+ * Only used as a hack because we have no other way of performing
+ * async actions in lustre between layers.
+ * Used on MDS to request object preallocations from more than one OST at a
+ * time.
+ */
 struct ptlrpc_request *ptlrpc_prep_fakereq(struct obd_import *imp,
                                            unsigned int timeout,
                                            ptlrpc_interpterer_t interpreter)
@@ -715,6 +843,7 @@ struct ptlrpc_request *ptlrpc_prep_fakereq(struct obd_import *imp,
         CFS_INIT_LIST_HEAD(&request->rq_history_list);
         CFS_INIT_LIST_HEAD(&request->rq_exp_list);
         cfs_waitq_init(&request->rq_reply_waitq);
+        cfs_waitq_init(&request->rq_set_waitq);
 
         request->rq_xid = ptlrpc_next_xid();
         cfs_atomic_set(&request->rq_refcount, 1);
@@ -722,21 +851,35 @@ struct ptlrpc_request *ptlrpc_prep_fakereq(struct obd_import *imp,
         RETURN(request);
 }
 
+/**
+ * Indicate that processing of "fake" request is finished.
+ */
 void ptlrpc_fakereq_finished(struct ptlrpc_request *req)
 {
-        /* if we kill request before timeout - need adjust counter */
-        if (req->rq_phase == RQ_PHASE_RPC) {
-                struct ptlrpc_request_set *set = req->rq_set;
+        struct ptlrpc_request_set *set = req->rq_set;
+        int wakeup = 0;
 
-                if (set)
-                        set->set_remaining --;
-        }
+        /* hold ref on the request to prevent others (ptlrpcd) to free it */
+        ptlrpc_request_addref(req);
+        cfs_list_del_init(&req->rq_list);
+
+        /* if we kill request before timeout - need adjust counter */
+        if (req->rq_phase == RQ_PHASE_RPC && set != NULL &&
+            cfs_atomic_dec_and_test(&set->set_remaining))
+                wakeup = 1;
 
         ptlrpc_rqphase_move(req, RQ_PHASE_COMPLETE);
-        cfs_list_del_init(&req->rq_list);
-}
 
+        /* Only need to call wakeup once when to be empty. */
+        if (wakeup)
+                cfs_waitq_signal(&set->set_waitq);
+        ptlrpc_req_finished(req);
+}
 
+/**
+ * Allocate and initialize new request set structure.
+ * 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;
@@ -745,9 +888,11 @@ struct ptlrpc_request_set *ptlrpc_prep_set(void)
         OBD_ALLOC(set, sizeof *set);
         if (!set)
                 RETURN(NULL);
+        cfs_atomic_set(&set->set_refcount, 1);
         CFS_INIT_LIST_HEAD(&set->set_requests);
         cfs_waitq_init(&set->set_waitq);
-        set->set_remaining = 0;
+        cfs_atomic_set(&set->set_new_count, 0);
+        cfs_atomic_set(&set->set_remaining, 0);
         cfs_spin_lock_init(&set->set_new_req_lock);
         CFS_INIT_LIST_HEAD(&set->set_new_requests);
         CFS_INIT_LIST_HEAD(&set->set_cblist);
@@ -755,7 +900,14 @@ struct ptlrpc_request_set *ptlrpc_prep_set(void)
         RETURN(set);
 }
 
-/* Finish with this set; opposite of prep_set. */
+/**
+ * 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)
 {
         cfs_list_t       *tmp;
@@ -765,7 +917,7 @@ void ptlrpc_set_destroy(struct ptlrpc_request_set *set)
         ENTRY;
 
         /* Requests on the set should either all be completed, or all be new */
-        expected_phase = (set->set_remaining == 0) ?
+        expected_phase = (cfs_atomic_read(&set->set_remaining) == 0) ?
                          RQ_PHASE_COMPLETE : RQ_PHASE_NEW;
         cfs_list_for_each (tmp, &set->set_requests) {
                 struct ptlrpc_request *req =
@@ -776,8 +928,9 @@ void ptlrpc_set_destroy(struct ptlrpc_request_set *set)
                 n++;
         }
 
-        LASSERTF(set->set_remaining == 0 || set->set_remaining == n, "%d / %d\n",
-                 set->set_remaining, n);
+        LASSERTF(cfs_atomic_read(&set->set_remaining) == 0 || 
+                 cfs_atomic_read(&set->set_remaining) == n, "%d / %d\n",
+                 cfs_atomic_read(&set->set_remaining), n);
 
         cfs_list_for_each_safe(tmp, next, &set->set_requests) {
                 struct ptlrpc_request *req =
@@ -789,19 +942,28 @@ void ptlrpc_set_destroy(struct ptlrpc_request_set *set)
 
                 if (req->rq_phase == RQ_PHASE_NEW) {
                         ptlrpc_req_interpret(NULL, req, -EBADR);
-                        set->set_remaining--;
+                        cfs_atomic_dec(&set->set_remaining);
                 }
 
+                cfs_spin_lock(&req->rq_lock);
                 req->rq_set = NULL;
+                req->rq_invalid_rqset = 0;
+                cfs_spin_unlock(&req->rq_lock);
+
                 ptlrpc_req_finished (req);
         }
 
-        LASSERT(set->set_remaining == 0);
+        LASSERT(cfs_atomic_read(&set->set_remaining) == 0);
 
-        OBD_FREE(set, sizeof(*set));
+        ptlrpc_reqset_put(set);
         EXIT;
 }
 
+/**
+ * Add a callback function \a fn to the set.
+ * This function would be called when all requests on this set are completed.
+ * The function will be passed \a data argument.
+ */
 int ptlrpc_set_add_cb(struct ptlrpc_request_set *set,
                       set_interpreter_func fn, void *data)
 {
@@ -818,44 +980,59 @@ int ptlrpc_set_add_cb(struct ptlrpc_request_set *set,
         RETURN(0);
 }
 
+/**
+ * Add a new request to the general purpose request set.
+ * Assumes request reference from the caller.
+ */
 void ptlrpc_set_add_req(struct ptlrpc_request_set *set,
                         struct ptlrpc_request *req)
 {
+        LASSERT(cfs_list_empty(&req->rq_set_chain));
+
         /* The set takes over the caller's request reference */
         cfs_list_add_tail(&req->rq_set_chain, &set->set_requests);
         req->rq_set = set;
-        set->set_remaining++;
+        cfs_atomic_inc(&set->set_remaining);
+        req->rq_queued_time = cfs_time_current();
 }
 
 /**
- * Lock so many callers can add things, the context that owns the set
- * is supposed to notice these and move them into the set proper.
+ * Add a request to a request with dedicated server thread
+ * and wake the thread to make any necessary processing.
+ * Currently only used for ptlrpcd.
  */
-int ptlrpc_set_add_new_req(struct ptlrpcd_ctl *pc,
+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;
 
-        /*
-         * Let caller know that we stopped and will not handle this request.
-         * It needs to take care itself of request.
-         */
-        if (cfs_test_bit(LIOD_STOP, &pc->pc_flags))
-                return -EALREADY;
+        LASSERT(req->rq_set == NULL);
+        LASSERT(cfs_test_bit(LIOD_STOP, &pc->pc_flags) == 0);
 
         cfs_spin_lock(&set->set_new_req_lock);
         /*
          * The set takes over the caller's request reference.
          */
-        cfs_list_add_tail(&req->rq_set_chain, &set->set_new_requests);
         req->rq_set = set;
+        req->rq_queued_time = cfs_time_current();
+        cfs_list_add_tail(&req->rq_set_chain, &set->set_new_requests);
+        count = cfs_atomic_inc_return(&set->set_new_count);
         cfs_spin_unlock(&set->set_new_req_lock);
 
-        cfs_waitq_signal(&set->set_waitq);
-        return 0;
+        /* Only need to call wakeup once for the first entry. */
+        if (count == 1) {
+                cfs_waitq_signal(&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++)
+                        cfs_waitq_signal(&pc->pc_partners[i]->pc_set->set_waitq);
+        }
 }
 
-/*
+/**
  * Based on the current state of the import, determine if the request
  * can be sent, is an error, or should be delayed.
  *
@@ -883,6 +1060,10 @@ static int ptlrpc_import_delay_req(struct obd_import *imp,
         } else if (imp->imp_state == LUSTRE_IMP_CLOSED) {
                 DEBUG_REQ(D_ERROR, req, "IMP_CLOSED ");
                 *status = -EIO;
+        } else if (ptlrpc_send_limit_expired(req)) {
+                /* probably doesn't need to be a D_ERROR after initial testing */
+                DEBUG_REQ(D_ERROR, req, "send limit expired ");
+                *status = -EIO;
         } else if (req->rq_send_state == LUSTRE_IMP_CONNECTING &&
                    imp->imp_state == LUSTRE_IMP_CONNECTING) {
                 /* allow CONNECT even if import is invalid */ ;
@@ -890,13 +1071,7 @@ static int ptlrpc_import_delay_req(struct obd_import *imp,
                         DEBUG_REQ(D_ERROR, req, "invalidate in flight");
                         *status = -EIO;
                 }
-        } else if ((imp->imp_invalid && (!imp->imp_recon_bk)) ||
-                                         imp->imp_obd->obd_no_recov) {
-                /* If the import has been invalidated (such as by an OST
-                 * failure), and if the import(MGC) tried all of its connection
-                 * list (Bug 13464), the request must fail with -ESHUTDOWN.
-                 * This indicates the requests should be discarded; an -EIO
-                 * may result in a resend of the request. */
+        } else if (imp->imp_invalid || imp->imp_obd->obd_no_recov) {
                 if (!imp->imp_deactive)
                           DEBUG_REQ(D_ERROR, req, "IMP_INVALID");
                 *status = -ESHUTDOWN; /* bz 12940 */
@@ -918,7 +1093,12 @@ static int ptlrpc_import_delay_req(struct obd_import *imp,
         RETURN(delay);
 }
 
-/* Conditionally suppress specific console messages */
+/**
+ * Decide if the eror message regarding provided request \a req
+ * should be printed to the console or not.
+ * Makes it's decision on request status and other properties.
+ * Returns 1 to print error on the system console or 0 if not.
+ */
 static int ptlrpc_console_allow(struct ptlrpc_request *req)
 {
         __u32 opc = lustre_msg_get_opc(req->rq_reqmsg);
@@ -942,6 +1122,10 @@ static int ptlrpc_console_allow(struct ptlrpc_request *req)
         return 1;
 }
 
+/**
+ * Check request processing status.
+ * Returns the status.
+ */
 static int ptlrpc_check_status(struct ptlrpc_request *req)
 {
         int err;
@@ -984,7 +1168,9 @@ static int ptlrpc_check_status(struct ptlrpc_request *req)
 }
 
 /**
- * save pre-versions for replay
+ * 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)
 {
@@ -1006,6 +1192,10 @@ static void ptlrpc_save_versions(struct ptlrpc_request *req)
 
 /**
  * Callback function called when client receives RPC reply for \a req.
+ * Returns 0 on success or error code.
+ * The return alue 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.
  */
 static int after_reply(struct ptlrpc_request *req)
 {
@@ -1016,14 +1206,26 @@ static int after_reply(struct ptlrpc_request *req)
         long timediff;
         ENTRY;
 
-        LASSERT(!req->rq_receiving_reply);
-        LASSERT(obd);
-        LASSERT(req->rq_nob_received <= req->rq_repbuf_len);
+        LASSERT(obd != NULL);
+        /* repbuf must be unlinked */
+        LASSERT(!req->rq_receiving_reply && !req->rq_must_unlink);
+
+        if (req->rq_reply_truncate) {
+                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);
+                }
 
-        if (req->rq_reply_truncate && !req->rq_no_resend) {
-                req->rq_resend = 1;
                 sptlrpc_cli_free_repbuf(req);
-                req->rq_replen = req->rq_nob_received;
+                /* 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;
+                req->rq_resend       = 1;
                 RETURN(0);
         }
 
@@ -1031,7 +1233,6 @@ static int after_reply(struct ptlrpc_request *req)
          * 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 (%d):", rc);
@@ -1064,7 +1265,7 @@ static int after_reply(struct ptlrpc_request *req)
         }
 
         if (lustre_msg_get_opc(req->rq_reqmsg) != OBD_PING)
-                OBD_FAIL_TIMEOUT(OBD_FAIL_PTLRPC_PAUSE_REP, obd_fail_val);
+                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_time(req->rq_repmsg));
@@ -1129,12 +1330,21 @@ static int after_reply(struct ptlrpc_request *req)
                                 lustre_msg_get_last_committed(req->rq_repmsg);
                 }
                 ptlrpc_free_committed(imp);
+
+                if (req->rq_transno > imp->imp_peer_committed_transno)
+                        ptlrpc_pinger_commit_expected(imp);
+
                 cfs_spin_unlock(&imp->imp_lock);
         }
 
         RETURN(rc);
 }
 
+/**
+ * Helper function to send request \a req over the network for the first time
+ * Also adjusts request phase.
+ * Returns 0 on success or error code.
+ */ 
 static int ptlrpc_send_new_req(struct ptlrpc_request *req)
 {
         struct obd_import     *imp;
@@ -1209,14 +1419,19 @@ static int ptlrpc_send_new_req(struct ptlrpc_request *req)
         RETURN(0);
 }
 
-/* this sends any unsent RPCs in @set and returns TRUE if all are sent */
+/**
+ * this sends any unsent RPCs in \a 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)
+ */
 int ptlrpc_check_set(const struct lu_env *env, struct ptlrpc_request_set *set)
 {
         cfs_list_t *tmp;
         int force_timer_recalc = 0;
         ENTRY;
 
-        if (set->set_remaining == 0)
+        if (cfs_atomic_read(&set->set_remaining) == 0)
                 RETURN(1);
 
         cfs_list_for_each(tmp, &set->set_requests) {
@@ -1224,6 +1439,7 @@ int ptlrpc_check_set(const struct lu_env *env, struct ptlrpc_request_set *set)
                         cfs_list_entry(tmp, struct ptlrpc_request,
                                        rq_set_chain);
                 struct obd_import *imp = req->rq_import;
+                int unregistered = 0;
                 int rc = 0;
 
                 if (req->rq_phase == RQ_PHASE_NEW &&
@@ -1297,10 +1513,21 @@ int ptlrpc_check_set(const struct lu_env *env, struct ptlrpc_request_set *set)
                         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) {
+                        cfs_spin_lock(&req->rq_lock);
                         req->rq_replied = 0;
+                        cfs_spin_unlock(&req->rq_lock);
                         if (req->rq_status == 0)
                                 req->rq_status = -EIO;
                         ptlrpc_rqphase_move(req, RQ_PHASE_INTERPRET);
@@ -1350,7 +1577,7 @@ int ptlrpc_check_set(const struct lu_env *env, struct ptlrpc_request_set *set)
                                         cfs_spin_unlock(&imp->imp_lock);
                                         GOTO(interpret, req->rq_status);
                                 }
-                                if (req->rq_no_resend && !req->rq_wait_ctx) {
+                                if (ptlrpc_no_resend(req) && !req->rq_wait_ctx) {
                                         req->rq_status = -ENOTCONN;
                                         ptlrpc_rqphase_move(req,
                                                 RQ_PHASE_INTERPRET);
@@ -1364,12 +1591,16 @@ int ptlrpc_check_set(const struct lu_env *env, struct ptlrpc_request_set *set)
 
                                 cfs_spin_unlock(&imp->imp_lock);
 
+                                cfs_spin_lock(&req->rq_lock);
                                 req->rq_waiting = 0;
+                                cfs_spin_unlock(&req->rq_lock);
 
-                                if (req->rq_timedout||req->rq_resend) {
+                                if (req->rq_timedout || req->rq_resend) {
                                         /* This is re-sending anyways,
                                          * let's mark req as resend. */
+                                        cfs_spin_lock(&req->rq_lock);
                                         req->rq_resend = 1;
+                                        cfs_spin_unlock(&req->rq_lock);
                                         if (req->rq_bulk) {
                                                 __u64 old_xid;
 
@@ -1393,15 +1624,21 @@ int ptlrpc_check_set(const struct lu_env *env, struct ptlrpc_request_set *set)
                                 if (status) {
                                         if (req->rq_err) {
                                                 req->rq_status = status;
+                                                cfs_spin_lock(&req->rq_lock);
                                                 req->rq_wait_ctx = 0;
+                                                cfs_spin_unlock(&req->rq_lock);
                                                 force_timer_recalc = 1;
                                         } else {
+                                                cfs_spin_lock(&req->rq_lock);
                                                 req->rq_wait_ctx = 1;
+                                                cfs_spin_unlock(&req->rq_lock);
                                         }
 
                                         continue;
                                 } else {
+                                        cfs_spin_lock(&req->rq_lock);
                                         req->rq_wait_ctx = 0;
+                                        cfs_spin_unlock(&req->rq_lock);
                                 }
 
                                 rc = ptl_send_rpc(req, 0);
@@ -1409,7 +1646,9 @@ int ptlrpc_check_set(const struct lu_env *env, struct ptlrpc_request_set *set)
                                         DEBUG_REQ(D_HA, req, "send failed (%d)",
                                                   rc);
                                         force_timer_recalc = 1;
+                                        cfs_spin_lock(&req->rq_lock);
                                         req->rq_net_err = 1;
+                                        cfs_spin_unlock(&req->rq_lock);
                                 }
                                 /* need to reset the timeout */
                                 force_timer_recalc = 1;
@@ -1437,6 +1676,12 @@ int ptlrpc_check_set(const struct lu_env *env, struct ptlrpc_request_set *set)
 
                         cfs_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)
                                 continue;
@@ -1474,8 +1719,11 @@ int ptlrpc_check_set(const struct lu_env *env, struct ptlrpc_request_set *set)
 
                 /* This moves to "unregistering" phase we need to wait for
                  * reply unlink. */
-                if (!ptlrpc_unregister_reply(req, 1))
+                if (!unregistered && !ptlrpc_unregister_reply(req, 1)) {
+                        /* start async bulk unlink too */
+                        ptlrpc_unregister_bulk(req, 1);
                         continue;
+                }
 
                 if (!ptlrpc_unregister_bulk(req, 1))
                         continue;
@@ -1507,15 +1755,19 @@ int ptlrpc_check_set(const struct lu_env *env, struct ptlrpc_request_set *set)
                 }
                 cfs_spin_unlock(&imp->imp_lock);
 
-                set->set_remaining--;
+                cfs_atomic_dec(&set->set_remaining);
                 cfs_waitq_broadcast(&imp->imp_recovery_waitq);
         }
 
         /* If we hit an error, we want to recover promptly. */
-        RETURN(set->set_remaining == 0 || force_timer_recalc);
+        RETURN(cfs_atomic_read(&set->set_remaining) == 0 || force_timer_recalc);
 }
 
-/* Return 1 if we should give up, else 0 */
+/**
+ * Time out request \a req. is \a async_unlink is set, that means do not 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;
@@ -1526,14 +1778,15 @@ int ptlrpc_expire_one_request(struct ptlrpc_request *req, int async_unlink)
         req->rq_timedout = 1;
         cfs_spin_unlock(&req->rq_lock);
 
-        DEBUG_REQ(req->rq_fake ? D_INFO : D_WARNING, req, 
-                  "Request x"LPU64" sent from %s to NID %s "CFS_DURATION_T"s "
-                  "ago has %s ("CFS_DURATION_T"s prior to deadline).\n",
-                  req->rq_xid, imp ? imp->imp_obd->obd_name : "<?>",
-                  imp ? libcfs_nid2str(imp->imp_connection->c_peer.nid) : "<?>",
-                  cfs_time_sub(cfs_time_current_sec(), req->rq_sent),
-                  req->rq_net_err ? "failed due to network error" : "timed out",
-                  cfs_time_sub(req->rq_deadline, req->rq_sent));
+        DEBUG_REQ(req->rq_fake ? D_INFO : D_WARNING, req, "Request "
+                  " sent has %s: [sent "CFS_DURATION_T"/"
+                  "real "CFS_DURATION_T"]",
+                  req->rq_net_err ? "failed due to network error" :
+                     ((req->rq_real_sent == 0 ||
+                       cfs_time_before(req->rq_real_sent, req->rq_sent) ||
+                       cfs_time_aftereq(req->rq_real_sent, req->rq_deadline)) ?
+                      "timed out for sent delay" : "timed out for slow reply"),
+                  req->rq_sent, req->rq_real_sent);
 
         if (imp != NULL && obd_debug_peer_on_timeout)
                 LNetCtl(IOC_LIBCFS_DEBUG_PEER, &imp->imp_connection->c_peer);
@@ -1575,7 +1828,7 @@ int ptlrpc_expire_one_request(struct ptlrpc_request *req, int async_unlink)
 
         /* if a request can't be resent we can't wait for an answer after
            the timeout */
-        if (req->rq_no_resend) {
+        if (ptlrpc_no_resend(req)) {
                 DEBUG_REQ(D_RPCTRACE, req, "TIMEOUT-NORESEND:");
                 rc = 1;
         }
@@ -1585,6 +1838,11 @@ int ptlrpc_expire_one_request(struct ptlrpc_request *req, int async_unlink)
         RETURN(rc);
 }
 
+/**
+ * Time out all uncompleted requests in request set pointed by \a data
+ * Callback used when waiting on sets with l_wait_event.
+ * Always returns 1.
+ */
 int ptlrpc_expired_set(void *data)
 {
         struct ptlrpc_request_set *set = data;
@@ -1629,6 +1887,9 @@ int ptlrpc_expired_set(void *data)
         RETURN(1);
 }
 
+/**
+ * Sets rq_intr flag in \a req under spinlock.
+ */
 void ptlrpc_mark_interrupted(struct ptlrpc_request *req)
 {
         cfs_spin_lock(&req->rq_lock);
@@ -1636,13 +1897,17 @@ void ptlrpc_mark_interrupted(struct ptlrpc_request *req)
         cfs_spin_unlock(&req->rq_lock);
 }
 
+/**
+ * Interrupts (sets interrupted flag) all uncompleted requests in
+ * a set \a data. Callback for l_wait_event for interruptible waits.
+ */
 void ptlrpc_interrupted_set(void *data)
 {
         struct ptlrpc_request_set *set = data;
         cfs_list_t *tmp;
 
         LASSERT(set != NULL);
-        CERROR("INTERRUPTED SET %p\n", set);
+        CDEBUG(D_RPCTRACE, "INTERRUPTED SET %p\n", set);
 
         cfs_list_for_each(tmp, &set->set_requests) {
                 struct ptlrpc_request *req =
@@ -1707,6 +1972,12 @@ int ptlrpc_set_next_timeout(struct ptlrpc_request_set *set)
         RETURN(timeout);
 }
 
+/**
+ * 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(struct ptlrpc_request_set *set)
 {
         cfs_list_t            *tmp;
@@ -1753,6 +2024,23 @@ int ptlrpc_set_wait(struct ptlrpc_request_set *set)
 
                 rc = l_wait_event(set->set_waitq, ptlrpc_check_set(NULL, set), &lwi);
 
+                /* LU-769 - if we ignored the signal because it was already
+                 * pending when we started, we need to handle it now or we risk
+                 * it being ignored forever */
+                if (rc == -ETIMEDOUT && !lwi.lwi_allow_intr &&
+                    cfs_signal_pending()) {
+                        cfs_sigset_t blocked_sigs =
+                                           cfs_block_sigsinv(LUSTRE_FATAL_SIGS);
+
+                        /* In fact we only interrupt for the "fatal" signals
+                         * like SIGINT or SIGKILL. We still ignore less
+                         * important signals since ptlrpc set is not easily
+                         * reentrant from userspace again */
+                        if (cfs_signal_pending())
+                                ptlrpc_interrupted_set(set);
+                        cfs_block_sigs(blocked_sigs);
+                }
+
                 LASSERT(rc == 0 || rc == -EINTR || rc == -ETIMEDOUT);
 
                 /* -EINTR => all requests have been flagged rq_intr so next
@@ -1762,9 +2050,18 @@ int ptlrpc_set_wait(struct ptlrpc_request_set *set)
                  * EINTR.
                  * I don't really care if we go once more round the loop in
                  * the error cases -eeb. */
-        } while (rc != 0 || set->set_remaining != 0);
+                if (rc == 0 && cfs_atomic_read(&set->set_remaining) == 0) {
+                        cfs_list_for_each(tmp, &set->set_requests) {
+                                req = cfs_list_entry(tmp, struct ptlrpc_request,
+                                                     rq_set_chain);
+                                cfs_spin_lock(&req->rq_lock);
+                                req->rq_invalid_rqset = 1;
+                                cfs_spin_unlock(&req->rq_lock);
+                        }
+                }
+        } while (rc != 0 || cfs_atomic_read(&set->set_remaining) != 0);
 
-        LASSERT(set->set_remaining == 0);
+        LASSERT(cfs_atomic_read(&set->set_remaining) == 0);
 
         rc = 0;
         cfs_list_for_each(tmp, &set->set_requests) {
@@ -1796,6 +2093,14 @@ int ptlrpc_set_wait(struct ptlrpc_request_set *set)
         RETURN(rc);
 }
 
+/**
+ * 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;
@@ -1858,12 +2163,22 @@ static void __ptlrpc_free_req(struct ptlrpc_request *request, int locked)
 }
 
 static int __ptlrpc_req_finished(struct ptlrpc_request *request, int locked);
+/**
+ * Drop one request reference. Must be called with import imp_lock held.
+ * When reference count drops to zero, reuqest is freed.
+ */
 void ptlrpc_req_finished_with_imp_lock(struct ptlrpc_request *request)
 {
         LASSERT_SPIN_LOCKED(&request->rq_import->imp_lock);
         (void)__ptlrpc_req_finished(request, 1);
 }
 
+/**
+ * Helper function
+ * Drops one reference count for request \a request.
+ * \a locked set indicates that caller holds import imp_lock.
+ * Frees the request whe reference count reaches zero.
+ */
 static int __ptlrpc_req_finished(struct ptlrpc_request *request, int locked)
 {
         ENTRY;
@@ -1888,21 +2203,29 @@ static int __ptlrpc_req_finished(struct ptlrpc_request *request, int locked)
         RETURN(0);
 }
 
+/**
+ * Drops one reference count for a request.
+ */
 void ptlrpc_req_finished(struct ptlrpc_request *request)
 {
         __ptlrpc_req_finished(request, 0);
 }
 
+/**
+ * Returns xid of a \a request
+ */
 __u64 ptlrpc_req_xid(struct ptlrpc_request *request)
 {
         return request->rq_xid;
 }
 EXPORT_SYMBOL(ptlrpc_req_xid);
 
-/* Disengage the client's reply buffer from the network
+/**
+ * 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.
  */
 int ptlrpc_unregister_reply(struct ptlrpc_request *request, int async)
 {
@@ -1977,7 +2300,14 @@ int ptlrpc_unregister_reply(struct ptlrpc_request *request, int async)
         RETURN(0);
 }
 
-/* caller must hold imp->imp_lock */
+/**
+ * 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 meetign first
+ * transno bigger than last_committed.
+ * caller must hold imp->imp_lock
+ */
 void ptlrpc_free_committed(struct obd_import *imp)
 {
         cfs_list_t *tmp, *saved;
@@ -1992,7 +2322,7 @@ void ptlrpc_free_committed(struct obd_import *imp)
 
         if (imp->imp_peer_committed_transno == imp->imp_last_transno_checked &&
             imp->imp_generation == imp->imp_last_generation_checked) {
-                CDEBUG(D_RPCTRACE, "%s: skip recheck: last_committed "LPU64"\n",
+                CDEBUG(D_INFO, "%s: skip recheck: last_committed "LPU64"\n",
                        imp->imp_obd->obd_name, imp->imp_peer_committed_transno);
                 EXIT;
                 return;
@@ -2031,7 +2361,7 @@ void ptlrpc_free_committed(struct obd_import *imp)
                         break;
                 }
 
-                DEBUG_REQ(D_RPCTRACE, req, "commit (last_committed "LPU64")",
+                DEBUG_REQ(D_INFO, req, "commit (last_committed "LPU64")",
                           imp->imp_peer_committed_transno);
 free_req:
                 cfs_spin_lock(&req->rq_lock);
@@ -2054,6 +2384,12 @@ void ptlrpc_cleanup_client(struct obd_import *imp)
         return;
 }
 
+/**
+ * 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");
@@ -2089,6 +2425,9 @@ void ptlrpc_restart_req(struct ptlrpc_request *req)
         cfs_spin_unlock(&req->rq_lock);
 }
 
+/**
+ * Grab additional reference on a request \a req
+ */
 struct ptlrpc_request *ptlrpc_request_addref(struct ptlrpc_request *req)
 {
         ENTRY;
@@ -2096,6 +2435,10 @@ struct ptlrpc_request *ptlrpc_request_addref(struct ptlrpc_request *req)
         RETURN(req);
 }
 
+/**
+ * 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)
 {
@@ -2148,6 +2491,10 @@ void ptlrpc_retain_replayable_request(struct ptlrpc_request *req,
         cfs_list_add(&req->rq_replay_list, &imp->imp_replay_list);
 }
 
+/**
+ * Send request and wait until it completes.
+ * Returns request processing status.
+ */
 int ptlrpc_queue_wait(struct ptlrpc_request *req)
 {
         struct ptlrpc_request_set *set;
@@ -2180,6 +2527,11 @@ struct ptlrpc_replay_async_args {
         int praa_old_status;
 };
 
+/**
+ * Callback used for replayed requests reply processing.
+ * In case of succesful reply calls registeresd 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 * data, int rc)
@@ -2208,6 +2560,7 @@ static int ptlrpc_replay_interpret(const struct lu_env *env,
                 imp->imp_vbr_failed = 1;
                 imp->imp_no_lock_replay = 1;
                 cfs_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) ==
@@ -2226,6 +2579,15 @@ static int ptlrpc_replay_interpret(const struct lu_env *env,
         cfs_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 "LPU64" is bigger than the "
+                          "replayed one: "LPU64, req->rq_transno,
+                          lustre_msg_get_transno(req->rq_reqmsg));
+                GOTO(out, rc = -EINVAL);
+        }
+
         DEBUG_REQ(D_HA, req, "got rep");
 
         /* let the callback do fixups, possibly including in the request */
@@ -2246,13 +2608,9 @@ static int ptlrpc_replay_interpret(const struct lu_env *env,
          * 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) {
-                cfs_spin_lock(&imp->imp_lock);
-                LASSERT(req->rq_transno <= imp->imp_last_replay_transno);
-                imp->imp_last_replay_transno = req->rq_transno;
-                cfs_spin_unlock(&imp->imp_lock);
-        } else
+        if (req->rq_transno == 0)
                 CERROR("Transno is 0 during replay!\n");
+
         /* continue with recovery */
         rc = ptlrpc_import_recovery_state_machine(imp);
  out:
@@ -2260,19 +2618,22 @@ static int ptlrpc_replay_interpret(const struct lu_env *env,
 
         if (rc != 0)
                 /* this replay failed, so restart recovery */
-                ptlrpc_connect_import(imp, NULL);
+                ptlrpc_connect_import(imp);
 
         RETURN(rc);
 }
 
+/**
+ * Prepares and queues request for replay.
+ * Adds it to ptlrpcd queue for actual sending.
+ * 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);
-        /* Not handling automatic bulk replay yet (or ever?) */
-        LASSERT(req->rq_bulk == NULL);
 
         LASSERT (sizeof (*aa) <= sizeof (req->rq_async_args));
         aa = ptlrpc_req_async_args(req);
@@ -2295,10 +2656,13 @@ int ptlrpc_replay_req(struct ptlrpc_request *req)
         cfs_atomic_inc(&req->rq_import->imp_replay_inflight);
         ptlrpc_request_addref(req); /* ptlrpcd needs a ref */
 
-        ptlrpcd_add_req(req, PSCOPE_OTHER);
+        ptlrpcd_add_req(req, PDL_POLICY_LOCAL, -1);
         RETURN(0);
 }
 
+/**
+ * Aborts all in-flight request on import \a imp sending and delayed lists
+ */
 void ptlrpc_abort_inflight(struct obd_import *imp)
 {
         cfs_list_t *tmp, *n;
@@ -2354,6 +2718,9 @@ void ptlrpc_abort_inflight(struct obd_import *imp)
         EXIT;
 }
 
+/**
+ * Abort all uncompleted requests in request set \a set
+ */
 void ptlrpc_abort_set(struct ptlrpc_request_set *set)
 {
         cfs_list_t *tmp, *pos;
@@ -2381,7 +2748,8 @@ void ptlrpc_abort_set(struct ptlrpc_request_set *set)
 static __u64 ptlrpc_last_xid;
 static cfs_spinlock_t ptlrpc_last_xid_lock;
 
-/* Initialize the XID for the node.  This is common among all requests on
+/**
+ * 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
@@ -2402,7 +2770,7 @@ void ptlrpc_init_xid(void)
 
         cfs_spin_lock_init(&ptlrpc_last_xid_lock);
         if (now < YEAR_2004) {
-                ll_get_random_bytes(&ptlrpc_last_xid, sizeof(ptlrpc_last_xid));
+                cfs_get_random_bytes(&ptlrpc_last_xid, sizeof(ptlrpc_last_xid));
                 ptlrpc_last_xid >>= 2;
                 ptlrpc_last_xid |= (1ULL << 61);
         } else {
@@ -2410,6 +2778,9 @@ void ptlrpc_init_xid(void)
         }
 }
 
+/**
+ * Increase xid and returns resultng new value to the caller.
+ */
 __u64 ptlrpc_next_xid(void)
 {
         __u64 tmp;
@@ -2419,6 +2790,10 @@ __u64 ptlrpc_next_xid(void)
         return tmp;
 }
 
+/**
+ * Get a glimpse at what next xid value might have been.
+ * Returns possible next xid.
+ */
 __u64 ptlrpc_sample_next_xid(void)
 {
 #if BITS_PER_LONG == 32