rds: Use RCU for the bind lookup searches
[linux-2.6.git] / net / rds / ib_rdma.c
1 /*
2  * Copyright (c) 2006 Oracle.  All rights reserved.
3  *
4  * This software is available to you under a choice of one of two
5  * licenses.  You may choose to be licensed under the terms of the GNU
6  * General Public License (GPL) Version 2, available from the file
7  * COPYING in the main directory of this source tree, or the
8  * OpenIB.org BSD license below:
9  *
10  *     Redistribution and use in source and binary forms, with or
11  *     without modification, are permitted provided that the following
12  *     conditions are met:
13  *
14  *      - Redistributions of source code must retain the above
15  *        copyright notice, this list of conditions and the following
16  *        disclaimer.
17  *
18  *      - Redistributions in binary form must reproduce the above
19  *        copyright notice, this list of conditions and the following
20  *        disclaimer in the documentation and/or other materials
21  *        provided with the distribution.
22  *
23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30  * SOFTWARE.
31  *
32  */
33 #include <linux/kernel.h>
34 #include <linux/slab.h>
35 #include <linux/rculist.h>
36
37 #include "rds.h"
38 #include "ib.h"
39
40
41 /*
42  * This is stored as mr->r_trans_private.
43  */
44 struct rds_ib_mr {
45         struct rds_ib_device    *device;
46         struct rds_ib_mr_pool   *pool;
47         struct ib_fmr           *fmr;
48         struct list_head        list;
49         unsigned int            remap_count;
50
51         struct scatterlist      *sg;
52         unsigned int            sg_len;
53         u64                     *dma;
54         int                     sg_dma_len;
55 };
56
57 /*
58  * Our own little FMR pool
59  */
60 struct rds_ib_mr_pool {
61         struct mutex            flush_lock;             /* serialize fmr invalidate */
62         struct work_struct      flush_worker;           /* flush worker */
63
64         spinlock_t              list_lock;              /* protect variables below */
65         atomic_t                item_count;             /* total # of MRs */
66         atomic_t                dirty_count;            /* # dirty of MRs */
67         struct list_head        drop_list;              /* MRs that have reached their max_maps limit */
68         struct list_head        free_list;              /* unused MRs */
69         struct list_head        clean_list;             /* unused & unamapped MRs */
70         atomic_t                free_pinned;            /* memory pinned by free MRs */
71         unsigned long           max_items;
72         unsigned long           max_items_soft;
73         unsigned long           max_free_pinned;
74         struct ib_fmr_attr      fmr_attr;
75 };
76
77 static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all);
78 static void rds_ib_teardown_mr(struct rds_ib_mr *ibmr);
79 static void rds_ib_mr_pool_flush_worker(struct work_struct *work);
80
81 static struct rds_ib_device *rds_ib_get_device(__be32 ipaddr)
82 {
83         struct rds_ib_device *rds_ibdev;
84         struct rds_ib_ipaddr *i_ipaddr;
85
86         list_for_each_entry(rds_ibdev, &rds_ib_devices, list) {
87                 rcu_read_lock();
88                 list_for_each_entry_rcu(i_ipaddr, &rds_ibdev->ipaddr_list, list) {
89                         if (i_ipaddr->ipaddr == ipaddr) {
90                                 rcu_read_unlock();
91                                 return rds_ibdev;
92                         }
93                 }
94                 rcu_read_unlock();
95         }
96
97         return NULL;
98 }
99
100 static int rds_ib_add_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
101 {
102         struct rds_ib_ipaddr *i_ipaddr;
103
104         i_ipaddr = kmalloc(sizeof *i_ipaddr, GFP_KERNEL);
105         if (!i_ipaddr)
106                 return -ENOMEM;
107
108         i_ipaddr->ipaddr = ipaddr;
109
110         spin_lock_irq(&rds_ibdev->spinlock);
111         list_add_tail_rcu(&i_ipaddr->list, &rds_ibdev->ipaddr_list);
112         spin_unlock_irq(&rds_ibdev->spinlock);
113
114         return 0;
115 }
116
117 static void rds_ib_remove_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
118 {
119         struct rds_ib_ipaddr *i_ipaddr;
120         struct rds_ib_ipaddr *to_free = NULL;
121
122
123         spin_lock_irq(&rds_ibdev->spinlock);
124         list_for_each_entry_rcu(i_ipaddr, &rds_ibdev->ipaddr_list, list) {
125                 if (i_ipaddr->ipaddr == ipaddr) {
126                         list_del_rcu(&i_ipaddr->list);
127                         to_free = i_ipaddr;
128                         break;
129                 }
130         }
131         spin_unlock_irq(&rds_ibdev->spinlock);
132
133         if (to_free) {
134                 synchronize_rcu();
135                 kfree(to_free);
136         }
137 }
138
139 int rds_ib_update_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
140 {
141         struct rds_ib_device *rds_ibdev_old;
142
143         rds_ibdev_old = rds_ib_get_device(ipaddr);
144         if (rds_ibdev_old)
145                 rds_ib_remove_ipaddr(rds_ibdev_old, ipaddr);
146
147         return rds_ib_add_ipaddr(rds_ibdev, ipaddr);
148 }
149
150 void rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)
151 {
152         struct rds_ib_connection *ic = conn->c_transport_data;
153
154         /* conn was previously on the nodev_conns_list */
155         spin_lock_irq(&ib_nodev_conns_lock);
156         BUG_ON(list_empty(&ib_nodev_conns));
157         BUG_ON(list_empty(&ic->ib_node));
158         list_del(&ic->ib_node);
159
160         spin_lock_irq(&rds_ibdev->spinlock);
161         list_add_tail(&ic->ib_node, &rds_ibdev->conn_list);
162         spin_unlock_irq(&rds_ibdev->spinlock);
163         spin_unlock_irq(&ib_nodev_conns_lock);
164
165         ic->rds_ibdev = rds_ibdev;
166 }
167
168 void rds_ib_remove_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)
169 {
170         struct rds_ib_connection *ic = conn->c_transport_data;
171
172         /* place conn on nodev_conns_list */
173         spin_lock(&ib_nodev_conns_lock);
174
175         spin_lock_irq(&rds_ibdev->spinlock);
176         BUG_ON(list_empty(&ic->ib_node));
177         list_del(&ic->ib_node);
178         spin_unlock_irq(&rds_ibdev->spinlock);
179
180         list_add_tail(&ic->ib_node, &ib_nodev_conns);
181
182         spin_unlock(&ib_nodev_conns_lock);
183
184         ic->rds_ibdev = NULL;
185 }
186
187 void __rds_ib_destroy_conns(struct list_head *list, spinlock_t *list_lock)
188 {
189         struct rds_ib_connection *ic, *_ic;
190         LIST_HEAD(tmp_list);
191
192         /* avoid calling conn_destroy with irqs off */
193         spin_lock_irq(list_lock);
194         list_splice(list, &tmp_list);
195         INIT_LIST_HEAD(list);
196         spin_unlock_irq(list_lock);
197
198         list_for_each_entry_safe(ic, _ic, &tmp_list, ib_node)
199                 rds_conn_destroy(ic->conn);
200 }
201
202 struct rds_ib_mr_pool *rds_ib_create_mr_pool(struct rds_ib_device *rds_ibdev)
203 {
204         struct rds_ib_mr_pool *pool;
205
206         pool = kzalloc(sizeof(*pool), GFP_KERNEL);
207         if (!pool)
208                 return ERR_PTR(-ENOMEM);
209
210         INIT_LIST_HEAD(&pool->free_list);
211         INIT_LIST_HEAD(&pool->drop_list);
212         INIT_LIST_HEAD(&pool->clean_list);
213         mutex_init(&pool->flush_lock);
214         spin_lock_init(&pool->list_lock);
215         INIT_WORK(&pool->flush_worker, rds_ib_mr_pool_flush_worker);
216
217         pool->fmr_attr.max_pages = fmr_message_size;
218         pool->fmr_attr.max_maps = rds_ibdev->fmr_max_remaps;
219         pool->fmr_attr.page_shift = PAGE_SHIFT;
220         pool->max_free_pinned = rds_ibdev->max_fmrs * fmr_message_size / 4;
221
222         /* We never allow more than max_items MRs to be allocated.
223          * When we exceed more than max_items_soft, we start freeing
224          * items more aggressively.
225          * Make sure that max_items > max_items_soft > max_items / 2
226          */
227         pool->max_items_soft = rds_ibdev->max_fmrs * 3 / 4;
228         pool->max_items = rds_ibdev->max_fmrs;
229
230         return pool;
231 }
232
233 void rds_ib_get_mr_info(struct rds_ib_device *rds_ibdev, struct rds_info_rdma_connection *iinfo)
234 {
235         struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
236
237         iinfo->rdma_mr_max = pool->max_items;
238         iinfo->rdma_mr_size = pool->fmr_attr.max_pages;
239 }
240
241 void rds_ib_destroy_mr_pool(struct rds_ib_mr_pool *pool)
242 {
243         flush_workqueue(rds_wq);
244         rds_ib_flush_mr_pool(pool, 1);
245         WARN_ON(atomic_read(&pool->item_count));
246         WARN_ON(atomic_read(&pool->free_pinned));
247         kfree(pool);
248 }
249
250 static inline struct rds_ib_mr *rds_ib_reuse_fmr(struct rds_ib_mr_pool *pool)
251 {
252         struct rds_ib_mr *ibmr = NULL;
253         unsigned long flags;
254
255         spin_lock_irqsave(&pool->list_lock, flags);
256         if (!list_empty(&pool->clean_list)) {
257                 ibmr = list_entry(pool->clean_list.next, struct rds_ib_mr, list);
258                 list_del_init(&ibmr->list);
259         }
260         spin_unlock_irqrestore(&pool->list_lock, flags);
261
262         return ibmr;
263 }
264
265 static struct rds_ib_mr *rds_ib_alloc_fmr(struct rds_ib_device *rds_ibdev)
266 {
267         struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
268         struct rds_ib_mr *ibmr = NULL;
269         int err = 0, iter = 0;
270
271         while (1) {
272                 ibmr = rds_ib_reuse_fmr(pool);
273                 if (ibmr)
274                         return ibmr;
275
276                 /* No clean MRs - now we have the choice of either
277                  * allocating a fresh MR up to the limit imposed by the
278                  * driver, or flush any dirty unused MRs.
279                  * We try to avoid stalling in the send path if possible,
280                  * so we allocate as long as we're allowed to.
281                  *
282                  * We're fussy with enforcing the FMR limit, though. If the driver
283                  * tells us we can't use more than N fmrs, we shouldn't start
284                  * arguing with it */
285                 if (atomic_inc_return(&pool->item_count) <= pool->max_items)
286                         break;
287
288                 atomic_dec(&pool->item_count);
289
290                 if (++iter > 2) {
291                         rds_ib_stats_inc(s_ib_rdma_mr_pool_depleted);
292                         return ERR_PTR(-EAGAIN);
293                 }
294
295                 /* We do have some empty MRs. Flush them out. */
296                 rds_ib_stats_inc(s_ib_rdma_mr_pool_wait);
297                 rds_ib_flush_mr_pool(pool, 0);
298         }
299
300         ibmr = kzalloc_node(sizeof(*ibmr), GFP_KERNEL, rdsibdev_to_node(rds_ibdev));
301         if (!ibmr) {
302                 err = -ENOMEM;
303                 goto out_no_cigar;
304         }
305
306         memset(ibmr, 0, sizeof(*ibmr));
307
308         ibmr->fmr = ib_alloc_fmr(rds_ibdev->pd,
309                         (IB_ACCESS_LOCAL_WRITE |
310                          IB_ACCESS_REMOTE_READ |
311                          IB_ACCESS_REMOTE_WRITE|
312                          IB_ACCESS_REMOTE_ATOMIC),
313
314                         &pool->fmr_attr);
315         if (IS_ERR(ibmr->fmr)) {
316                 err = PTR_ERR(ibmr->fmr);
317                 ibmr->fmr = NULL;
318                 printk(KERN_WARNING "RDS/IB: ib_alloc_fmr failed (err=%d)\n", err);
319                 goto out_no_cigar;
320         }
321
322         rds_ib_stats_inc(s_ib_rdma_mr_alloc);
323         return ibmr;
324
325 out_no_cigar:
326         if (ibmr) {
327                 if (ibmr->fmr)
328                         ib_dealloc_fmr(ibmr->fmr);
329                 kfree(ibmr);
330         }
331         atomic_dec(&pool->item_count);
332         return ERR_PTR(err);
333 }
334
335 static int rds_ib_map_fmr(struct rds_ib_device *rds_ibdev, struct rds_ib_mr *ibmr,
336                struct scatterlist *sg, unsigned int nents)
337 {
338         struct ib_device *dev = rds_ibdev->dev;
339         struct scatterlist *scat = sg;
340         u64 io_addr = 0;
341         u64 *dma_pages;
342         u32 len;
343         int page_cnt, sg_dma_len;
344         int i, j;
345         int ret;
346
347         sg_dma_len = ib_dma_map_sg(dev, sg, nents,
348                                  DMA_BIDIRECTIONAL);
349         if (unlikely(!sg_dma_len)) {
350                 printk(KERN_WARNING "RDS/IB: dma_map_sg failed!\n");
351                 return -EBUSY;
352         }
353
354         len = 0;
355         page_cnt = 0;
356
357         for (i = 0; i < sg_dma_len; ++i) {
358                 unsigned int dma_len = ib_sg_dma_len(dev, &scat[i]);
359                 u64 dma_addr = ib_sg_dma_address(dev, &scat[i]);
360
361                 if (dma_addr & ~PAGE_MASK) {
362                         if (i > 0)
363                                 return -EINVAL;
364                         else
365                                 ++page_cnt;
366                 }
367                 if ((dma_addr + dma_len) & ~PAGE_MASK) {
368                         if (i < sg_dma_len - 1)
369                                 return -EINVAL;
370                         else
371                                 ++page_cnt;
372                 }
373
374                 len += dma_len;
375         }
376
377         page_cnt += len >> PAGE_SHIFT;
378         if (page_cnt > fmr_message_size)
379                 return -EINVAL;
380
381         dma_pages = kmalloc_node(sizeof(u64) * page_cnt, GFP_ATOMIC,
382                                  rdsibdev_to_node(rds_ibdev));
383         if (!dma_pages)
384                 return -ENOMEM;
385
386         page_cnt = 0;
387         for (i = 0; i < sg_dma_len; ++i) {
388                 unsigned int dma_len = ib_sg_dma_len(dev, &scat[i]);
389                 u64 dma_addr = ib_sg_dma_address(dev, &scat[i]);
390
391                 for (j = 0; j < dma_len; j += PAGE_SIZE)
392                         dma_pages[page_cnt++] =
393                                 (dma_addr & PAGE_MASK) + j;
394         }
395
396         ret = ib_map_phys_fmr(ibmr->fmr,
397                                    dma_pages, page_cnt, io_addr);
398         if (ret)
399                 goto out;
400
401         /* Success - we successfully remapped the MR, so we can
402          * safely tear down the old mapping. */
403         rds_ib_teardown_mr(ibmr);
404
405         ibmr->sg = scat;
406         ibmr->sg_len = nents;
407         ibmr->sg_dma_len = sg_dma_len;
408         ibmr->remap_count++;
409
410         rds_ib_stats_inc(s_ib_rdma_mr_used);
411         ret = 0;
412
413 out:
414         kfree(dma_pages);
415
416         return ret;
417 }
418
419 void rds_ib_sync_mr(void *trans_private, int direction)
420 {
421         struct rds_ib_mr *ibmr = trans_private;
422         struct rds_ib_device *rds_ibdev = ibmr->device;
423
424         switch (direction) {
425         case DMA_FROM_DEVICE:
426                 ib_dma_sync_sg_for_cpu(rds_ibdev->dev, ibmr->sg,
427                         ibmr->sg_dma_len, DMA_BIDIRECTIONAL);
428                 break;
429         case DMA_TO_DEVICE:
430                 ib_dma_sync_sg_for_device(rds_ibdev->dev, ibmr->sg,
431                         ibmr->sg_dma_len, DMA_BIDIRECTIONAL);
432                 break;
433         }
434 }
435
436 static void __rds_ib_teardown_mr(struct rds_ib_mr *ibmr)
437 {
438         struct rds_ib_device *rds_ibdev = ibmr->device;
439
440         if (ibmr->sg_dma_len) {
441                 ib_dma_unmap_sg(rds_ibdev->dev,
442                                 ibmr->sg, ibmr->sg_len,
443                                 DMA_BIDIRECTIONAL);
444                 ibmr->sg_dma_len = 0;
445         }
446
447         /* Release the s/g list */
448         if (ibmr->sg_len) {
449                 unsigned int i;
450
451                 for (i = 0; i < ibmr->sg_len; ++i) {
452                         struct page *page = sg_page(&ibmr->sg[i]);
453
454                         /* FIXME we need a way to tell a r/w MR
455                          * from a r/o MR */
456                         BUG_ON(irqs_disabled());
457                         set_page_dirty(page);
458                         put_page(page);
459                 }
460                 kfree(ibmr->sg);
461
462                 ibmr->sg = NULL;
463                 ibmr->sg_len = 0;
464         }
465 }
466
467 static void rds_ib_teardown_mr(struct rds_ib_mr *ibmr)
468 {
469         unsigned int pinned = ibmr->sg_len;
470
471         __rds_ib_teardown_mr(ibmr);
472         if (pinned) {
473                 struct rds_ib_device *rds_ibdev = ibmr->device;
474                 struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
475
476                 atomic_sub(pinned, &pool->free_pinned);
477         }
478 }
479
480 static inline unsigned int rds_ib_flush_goal(struct rds_ib_mr_pool *pool, int free_all)
481 {
482         unsigned int item_count;
483
484         item_count = atomic_read(&pool->item_count);
485         if (free_all)
486                 return item_count;
487
488         return 0;
489 }
490
491 /*
492  * Flush our pool of MRs.
493  * At a minimum, all currently unused MRs are unmapped.
494  * If the number of MRs allocated exceeds the limit, we also try
495  * to free as many MRs as needed to get back to this limit.
496  */
497 static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all)
498 {
499         struct rds_ib_mr *ibmr, *next;
500         LIST_HEAD(unmap_list);
501         LIST_HEAD(fmr_list);
502         unsigned long unpinned = 0;
503         unsigned long flags;
504         unsigned int nfreed = 0, ncleaned = 0, free_goal;
505         int ret = 0;
506
507         rds_ib_stats_inc(s_ib_rdma_mr_pool_flush);
508
509         mutex_lock(&pool->flush_lock);
510
511         spin_lock_irqsave(&pool->list_lock, flags);
512         /* Get the list of all MRs to be dropped. Ordering matters -
513          * we want to put drop_list ahead of free_list. */
514         list_splice_init(&pool->free_list, &unmap_list);
515         list_splice_init(&pool->drop_list, &unmap_list);
516         if (free_all)
517                 list_splice_init(&pool->clean_list, &unmap_list);
518         spin_unlock_irqrestore(&pool->list_lock, flags);
519
520         free_goal = rds_ib_flush_goal(pool, free_all);
521
522         if (list_empty(&unmap_list))
523                 goto out;
524
525         /* String all ib_mr's onto one list and hand them to ib_unmap_fmr */
526         list_for_each_entry(ibmr, &unmap_list, list)
527                 list_add(&ibmr->fmr->list, &fmr_list);
528         ret = ib_unmap_fmr(&fmr_list);
529         if (ret)
530                 printk(KERN_WARNING "RDS/IB: ib_unmap_fmr failed (err=%d)\n", ret);
531
532         /* Now we can destroy the DMA mapping and unpin any pages */
533         list_for_each_entry_safe(ibmr, next, &unmap_list, list) {
534                 unpinned += ibmr->sg_len;
535                 __rds_ib_teardown_mr(ibmr);
536                 if (nfreed < free_goal || ibmr->remap_count >= pool->fmr_attr.max_maps) {
537                         rds_ib_stats_inc(s_ib_rdma_mr_free);
538                         list_del(&ibmr->list);
539                         ib_dealloc_fmr(ibmr->fmr);
540                         kfree(ibmr);
541                         nfreed++;
542                 }
543                 ncleaned++;
544         }
545
546         spin_lock_irqsave(&pool->list_lock, flags);
547         list_splice(&unmap_list, &pool->clean_list);
548         spin_unlock_irqrestore(&pool->list_lock, flags);
549
550         atomic_sub(unpinned, &pool->free_pinned);
551         atomic_sub(ncleaned, &pool->dirty_count);
552         atomic_sub(nfreed, &pool->item_count);
553
554 out:
555         mutex_unlock(&pool->flush_lock);
556         return ret;
557 }
558
559 static void rds_ib_mr_pool_flush_worker(struct work_struct *work)
560 {
561         struct rds_ib_mr_pool *pool = container_of(work, struct rds_ib_mr_pool, flush_worker);
562
563         rds_ib_flush_mr_pool(pool, 0);
564 }
565
566 void rds_ib_free_mr(void *trans_private, int invalidate)
567 {
568         struct rds_ib_mr *ibmr = trans_private;
569         struct rds_ib_device *rds_ibdev = ibmr->device;
570         struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
571         unsigned long flags;
572
573         rdsdebug("RDS/IB: free_mr nents %u\n", ibmr->sg_len);
574
575         /* Return it to the pool's free list */
576         spin_lock_irqsave(&pool->list_lock, flags);
577         if (ibmr->remap_count >= pool->fmr_attr.max_maps)
578                 list_add(&ibmr->list, &pool->drop_list);
579         else
580                 list_add(&ibmr->list, &pool->free_list);
581
582         atomic_add(ibmr->sg_len, &pool->free_pinned);
583         atomic_inc(&pool->dirty_count);
584         spin_unlock_irqrestore(&pool->list_lock, flags);
585
586         /* If we've pinned too many pages, request a flush */
587         if (atomic_read(&pool->free_pinned) >= pool->max_free_pinned ||
588             atomic_read(&pool->dirty_count) >= pool->max_items / 10)
589                 queue_work(rds_wq, &pool->flush_worker);
590
591         if (invalidate) {
592                 if (likely(!in_interrupt())) {
593                         rds_ib_flush_mr_pool(pool, 0);
594                 } else {
595                         /* We get here if the user created a MR marked
596                          * as use_once and invalidate at the same time. */
597                         queue_work(rds_wq, &pool->flush_worker);
598                 }
599         }
600 }
601
602 void rds_ib_flush_mrs(void)
603 {
604         struct rds_ib_device *rds_ibdev;
605
606         list_for_each_entry(rds_ibdev, &rds_ib_devices, list) {
607                 struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
608
609                 if (pool)
610                         rds_ib_flush_mr_pool(pool, 0);
611         }
612 }
613
614 void *rds_ib_get_mr(struct scatterlist *sg, unsigned long nents,
615                     struct rds_sock *rs, u32 *key_ret)
616 {
617         struct rds_ib_device *rds_ibdev;
618         struct rds_ib_mr *ibmr = NULL;
619         int ret;
620
621         rds_ibdev = rds_ib_get_device(rs->rs_bound_addr);
622         if (!rds_ibdev) {
623                 ret = -ENODEV;
624                 goto out;
625         }
626
627         if (!rds_ibdev->mr_pool) {
628                 ret = -ENODEV;
629                 goto out;
630         }
631
632         ibmr = rds_ib_alloc_fmr(rds_ibdev);
633         if (IS_ERR(ibmr))
634                 return ibmr;
635
636         ret = rds_ib_map_fmr(rds_ibdev, ibmr, sg, nents);
637         if (ret == 0)
638                 *key_ret = ibmr->fmr->rkey;
639         else
640                 printk(KERN_WARNING "RDS/IB: map_fmr failed (errno=%d)\n", ret);
641
642         ibmr->device = rds_ibdev;
643
644  out:
645         if (ret) {
646                 if (ibmr)
647                         rds_ib_free_mr(ibmr, 0);
648                 ibmr = ERR_PTR(ret);
649         }
650         return ibmr;
651 }