cc341cd70c87fd7de8bb58c96ee0d701a2366169
[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         ibmr->fmr = ib_alloc_fmr(rds_ibdev->pd,
307                         (IB_ACCESS_LOCAL_WRITE |
308                          IB_ACCESS_REMOTE_READ |
309                          IB_ACCESS_REMOTE_WRITE|
310                          IB_ACCESS_REMOTE_ATOMIC),
311
312                         &pool->fmr_attr);
313         if (IS_ERR(ibmr->fmr)) {
314                 err = PTR_ERR(ibmr->fmr);
315                 ibmr->fmr = NULL;
316                 printk(KERN_WARNING "RDS/IB: ib_alloc_fmr failed (err=%d)\n", err);
317                 goto out_no_cigar;
318         }
319
320         rds_ib_stats_inc(s_ib_rdma_mr_alloc);
321         return ibmr;
322
323 out_no_cigar:
324         if (ibmr) {
325                 if (ibmr->fmr)
326                         ib_dealloc_fmr(ibmr->fmr);
327                 kfree(ibmr);
328         }
329         atomic_dec(&pool->item_count);
330         return ERR_PTR(err);
331 }
332
333 static int rds_ib_map_fmr(struct rds_ib_device *rds_ibdev, struct rds_ib_mr *ibmr,
334                struct scatterlist *sg, unsigned int nents)
335 {
336         struct ib_device *dev = rds_ibdev->dev;
337         struct scatterlist *scat = sg;
338         u64 io_addr = 0;
339         u64 *dma_pages;
340         u32 len;
341         int page_cnt, sg_dma_len;
342         int i, j;
343         int ret;
344
345         sg_dma_len = ib_dma_map_sg(dev, sg, nents,
346                                  DMA_BIDIRECTIONAL);
347         if (unlikely(!sg_dma_len)) {
348                 printk(KERN_WARNING "RDS/IB: dma_map_sg failed!\n");
349                 return -EBUSY;
350         }
351
352         len = 0;
353         page_cnt = 0;
354
355         for (i = 0; i < sg_dma_len; ++i) {
356                 unsigned int dma_len = ib_sg_dma_len(dev, &scat[i]);
357                 u64 dma_addr = ib_sg_dma_address(dev, &scat[i]);
358
359                 if (dma_addr & ~PAGE_MASK) {
360                         if (i > 0)
361                                 return -EINVAL;
362                         else
363                                 ++page_cnt;
364                 }
365                 if ((dma_addr + dma_len) & ~PAGE_MASK) {
366                         if (i < sg_dma_len - 1)
367                                 return -EINVAL;
368                         else
369                                 ++page_cnt;
370                 }
371
372                 len += dma_len;
373         }
374
375         page_cnt += len >> PAGE_SHIFT;
376         if (page_cnt > fmr_message_size)
377                 return -EINVAL;
378
379         dma_pages = kmalloc_node(sizeof(u64) * page_cnt, GFP_ATOMIC,
380                                  rdsibdev_to_node(rds_ibdev));
381         if (!dma_pages)
382                 return -ENOMEM;
383
384         page_cnt = 0;
385         for (i = 0; i < sg_dma_len; ++i) {
386                 unsigned int dma_len = ib_sg_dma_len(dev, &scat[i]);
387                 u64 dma_addr = ib_sg_dma_address(dev, &scat[i]);
388
389                 for (j = 0; j < dma_len; j += PAGE_SIZE)
390                         dma_pages[page_cnt++] =
391                                 (dma_addr & PAGE_MASK) + j;
392         }
393
394         ret = ib_map_phys_fmr(ibmr->fmr,
395                                    dma_pages, page_cnt, io_addr);
396         if (ret)
397                 goto out;
398
399         /* Success - we successfully remapped the MR, so we can
400          * safely tear down the old mapping. */
401         rds_ib_teardown_mr(ibmr);
402
403         ibmr->sg = scat;
404         ibmr->sg_len = nents;
405         ibmr->sg_dma_len = sg_dma_len;
406         ibmr->remap_count++;
407
408         rds_ib_stats_inc(s_ib_rdma_mr_used);
409         ret = 0;
410
411 out:
412         kfree(dma_pages);
413
414         return ret;
415 }
416
417 void rds_ib_sync_mr(void *trans_private, int direction)
418 {
419         struct rds_ib_mr *ibmr = trans_private;
420         struct rds_ib_device *rds_ibdev = ibmr->device;
421
422         switch (direction) {
423         case DMA_FROM_DEVICE:
424                 ib_dma_sync_sg_for_cpu(rds_ibdev->dev, ibmr->sg,
425                         ibmr->sg_dma_len, DMA_BIDIRECTIONAL);
426                 break;
427         case DMA_TO_DEVICE:
428                 ib_dma_sync_sg_for_device(rds_ibdev->dev, ibmr->sg,
429                         ibmr->sg_dma_len, DMA_BIDIRECTIONAL);
430                 break;
431         }
432 }
433
434 static void __rds_ib_teardown_mr(struct rds_ib_mr *ibmr)
435 {
436         struct rds_ib_device *rds_ibdev = ibmr->device;
437
438         if (ibmr->sg_dma_len) {
439                 ib_dma_unmap_sg(rds_ibdev->dev,
440                                 ibmr->sg, ibmr->sg_len,
441                                 DMA_BIDIRECTIONAL);
442                 ibmr->sg_dma_len = 0;
443         }
444
445         /* Release the s/g list */
446         if (ibmr->sg_len) {
447                 unsigned int i;
448
449                 for (i = 0; i < ibmr->sg_len; ++i) {
450                         struct page *page = sg_page(&ibmr->sg[i]);
451
452                         /* FIXME we need a way to tell a r/w MR
453                          * from a r/o MR */
454                         BUG_ON(irqs_disabled());
455                         set_page_dirty(page);
456                         put_page(page);
457                 }
458                 kfree(ibmr->sg);
459
460                 ibmr->sg = NULL;
461                 ibmr->sg_len = 0;
462         }
463 }
464
465 static void rds_ib_teardown_mr(struct rds_ib_mr *ibmr)
466 {
467         unsigned int pinned = ibmr->sg_len;
468
469         __rds_ib_teardown_mr(ibmr);
470         if (pinned) {
471                 struct rds_ib_device *rds_ibdev = ibmr->device;
472                 struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
473
474                 atomic_sub(pinned, &pool->free_pinned);
475         }
476 }
477
478 static inline unsigned int rds_ib_flush_goal(struct rds_ib_mr_pool *pool, int free_all)
479 {
480         unsigned int item_count;
481
482         item_count = atomic_read(&pool->item_count);
483         if (free_all)
484                 return item_count;
485
486         return 0;
487 }
488
489 /*
490  * Flush our pool of MRs.
491  * At a minimum, all currently unused MRs are unmapped.
492  * If the number of MRs allocated exceeds the limit, we also try
493  * to free as many MRs as needed to get back to this limit.
494  */
495 static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all)
496 {
497         struct rds_ib_mr *ibmr, *next;
498         LIST_HEAD(unmap_list);
499         LIST_HEAD(fmr_list);
500         unsigned long unpinned = 0;
501         unsigned long flags;
502         unsigned int nfreed = 0, ncleaned = 0, free_goal;
503         int ret = 0;
504
505         rds_ib_stats_inc(s_ib_rdma_mr_pool_flush);
506
507         mutex_lock(&pool->flush_lock);
508
509         spin_lock_irqsave(&pool->list_lock, flags);
510         /* Get the list of all MRs to be dropped. Ordering matters -
511          * we want to put drop_list ahead of free_list. */
512         list_splice_init(&pool->free_list, &unmap_list);
513         list_splice_init(&pool->drop_list, &unmap_list);
514         if (free_all)
515                 list_splice_init(&pool->clean_list, &unmap_list);
516         spin_unlock_irqrestore(&pool->list_lock, flags);
517
518         free_goal = rds_ib_flush_goal(pool, free_all);
519
520         if (list_empty(&unmap_list))
521                 goto out;
522
523         /* String all ib_mr's onto one list and hand them to ib_unmap_fmr */
524         list_for_each_entry(ibmr, &unmap_list, list)
525                 list_add(&ibmr->fmr->list, &fmr_list);
526         ret = ib_unmap_fmr(&fmr_list);
527         if (ret)
528                 printk(KERN_WARNING "RDS/IB: ib_unmap_fmr failed (err=%d)\n", ret);
529
530         /* Now we can destroy the DMA mapping and unpin any pages */
531         list_for_each_entry_safe(ibmr, next, &unmap_list, list) {
532                 unpinned += ibmr->sg_len;
533                 __rds_ib_teardown_mr(ibmr);
534                 if (nfreed < free_goal || ibmr->remap_count >= pool->fmr_attr.max_maps) {
535                         rds_ib_stats_inc(s_ib_rdma_mr_free);
536                         list_del(&ibmr->list);
537                         ib_dealloc_fmr(ibmr->fmr);
538                         kfree(ibmr);
539                         nfreed++;
540                 }
541                 ncleaned++;
542         }
543
544         spin_lock_irqsave(&pool->list_lock, flags);
545         list_splice(&unmap_list, &pool->clean_list);
546         spin_unlock_irqrestore(&pool->list_lock, flags);
547
548         atomic_sub(unpinned, &pool->free_pinned);
549         atomic_sub(ncleaned, &pool->dirty_count);
550         atomic_sub(nfreed, &pool->item_count);
551
552 out:
553         mutex_unlock(&pool->flush_lock);
554         return ret;
555 }
556
557 static void rds_ib_mr_pool_flush_worker(struct work_struct *work)
558 {
559         struct rds_ib_mr_pool *pool = container_of(work, struct rds_ib_mr_pool, flush_worker);
560
561         rds_ib_flush_mr_pool(pool, 0);
562 }
563
564 void rds_ib_free_mr(void *trans_private, int invalidate)
565 {
566         struct rds_ib_mr *ibmr = trans_private;
567         struct rds_ib_device *rds_ibdev = ibmr->device;
568         struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
569         unsigned long flags;
570
571         rdsdebug("RDS/IB: free_mr nents %u\n", ibmr->sg_len);
572
573         /* Return it to the pool's free list */
574         spin_lock_irqsave(&pool->list_lock, flags);
575         if (ibmr->remap_count >= pool->fmr_attr.max_maps)
576                 list_add(&ibmr->list, &pool->drop_list);
577         else
578                 list_add(&ibmr->list, &pool->free_list);
579
580         atomic_add(ibmr->sg_len, &pool->free_pinned);
581         atomic_inc(&pool->dirty_count);
582         spin_unlock_irqrestore(&pool->list_lock, flags);
583
584         /* If we've pinned too many pages, request a flush */
585         if (atomic_read(&pool->free_pinned) >= pool->max_free_pinned ||
586             atomic_read(&pool->dirty_count) >= pool->max_items / 10)
587                 queue_work(rds_wq, &pool->flush_worker);
588
589         if (invalidate) {
590                 if (likely(!in_interrupt())) {
591                         rds_ib_flush_mr_pool(pool, 0);
592                 } else {
593                         /* We get here if the user created a MR marked
594                          * as use_once and invalidate at the same time. */
595                         queue_work(rds_wq, &pool->flush_worker);
596                 }
597         }
598 }
599
600 void rds_ib_flush_mrs(void)
601 {
602         struct rds_ib_device *rds_ibdev;
603
604         list_for_each_entry(rds_ibdev, &rds_ib_devices, list) {
605                 struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
606
607                 if (pool)
608                         rds_ib_flush_mr_pool(pool, 0);
609         }
610 }
611
612 void *rds_ib_get_mr(struct scatterlist *sg, unsigned long nents,
613                     struct rds_sock *rs, u32 *key_ret)
614 {
615         struct rds_ib_device *rds_ibdev;
616         struct rds_ib_mr *ibmr = NULL;
617         int ret;
618
619         rds_ibdev = rds_ib_get_device(rs->rs_bound_addr);
620         if (!rds_ibdev) {
621                 ret = -ENODEV;
622                 goto out;
623         }
624
625         if (!rds_ibdev->mr_pool) {
626                 ret = -ENODEV;
627                 goto out;
628         }
629
630         ibmr = rds_ib_alloc_fmr(rds_ibdev);
631         if (IS_ERR(ibmr))
632                 return ibmr;
633
634         ret = rds_ib_map_fmr(rds_ibdev, ibmr, sg, nents);
635         if (ret == 0)
636                 *key_ret = ibmr->fmr->rkey;
637         else
638                 printk(KERN_WARNING "RDS/IB: map_fmr failed (errno=%d)\n", ret);
639
640         ibmr->device = rds_ibdev;
641
642  out:
643         if (ret) {
644                 if (ibmr)
645                         rds_ib_free_mr(ibmr, 0);
646                 ibmr = ERR_PTR(ret);
647         }
648         return ibmr;
649 }