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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Device operations for the pnfs nfs4 file layout driver.
4 *
5 * Copyright (c) 2014, Primary Data, Inc. All rights reserved.
6 *
7 * Tao Peng <[email protected]>
8 */
9
10#include <linux/nfs_fs.h>
11#include <linux/vmalloc.h>
12#include <linux/module.h>
13#include <linux/sunrpc/addr.h>
14
15#include "../internal.h"
16#include "../nfs4session.h"
17#include "flexfilelayout.h"
18
19#define NFSDBG_FACILITY NFSDBG_PNFS_LD
20
21static unsigned int dataserver_timeo = NFS_DEF_TCP_TIMEO;
22static unsigned int dataserver_retrans;
23
24static bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg);
25
26void nfs4_ff_layout_put_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
27{
28 if (!IS_ERR_OR_NULL(mirror_ds))
29 nfs4_put_deviceid_node(&mirror_ds->id_node);
30}
31
32void nfs4_ff_layout_free_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
33{
34 nfs4_print_deviceid(&mirror_ds->id_node.deviceid);
35 nfs4_pnfs_ds_put(mirror_ds->ds);
36 kfree(mirror_ds->ds_versions);
37 kfree_rcu(mirror_ds, id_node.rcu);
38}
39
40/* Decode opaque device data and construct new_ds using it */
41struct nfs4_ff_layout_ds *
42nfs4_ff_alloc_deviceid_node(struct nfs_server *server, struct pnfs_device *pdev,
43 gfp_t gfp_flags)
44{
45 struct xdr_stream stream;
46 struct xdr_buf buf;
47 struct folio *scratch;
48 struct list_head dsaddrs;
49 struct nfs4_pnfs_ds_addr *da;
50 struct nfs4_ff_layout_ds *new_ds = NULL;
51 struct nfs4_ff_ds_version *ds_versions = NULL;
52 struct net *net = server->nfs_client->cl_net;
53 u32 mp_count;
54 u32 version_count;
55 __be32 *p;
56 int i, ret = -ENOMEM;
57
58 /* set up xdr stream */
59 scratch = folio_alloc(gfp_flags, 0);
60 if (!scratch)
61 goto out_err;
62
63 new_ds = kzalloc_obj(struct nfs4_ff_layout_ds, gfp_flags);
64 if (!new_ds)
65 goto out_scratch;
66
67 nfs4_init_deviceid_node(&new_ds->id_node,
68 server,
69 &pdev->dev_id);
70 INIT_LIST_HEAD(&dsaddrs);
71
72 xdr_init_decode_pages(&stream, &buf, pdev->pages, pdev->pglen);
73 xdr_set_scratch_folio(&stream, scratch);
74
75 /* multipath count */
76 p = xdr_inline_decode(&stream, 4);
77 if (unlikely(!p))
78 goto out_err_drain_dsaddrs;
79 mp_count = be32_to_cpup(p);
80 dprintk("%s: multipath ds count %d\n", __func__, mp_count);
81
82 for (i = 0; i < mp_count; i++) {
83 /* multipath ds */
84 da = nfs4_decode_mp_ds_addr(net, &stream, gfp_flags);
85 if (da)
86 list_add_tail(&da->da_node, &dsaddrs);
87 }
88 if (list_empty(&dsaddrs)) {
89 dprintk("%s: no suitable DS addresses found\n",
90 __func__);
91 ret = -ENOMEDIUM;
92 goto out_err_drain_dsaddrs;
93 }
94
95 /* version count */
96 p = xdr_inline_decode(&stream, 4);
97 if (unlikely(!p))
98 goto out_err_drain_dsaddrs;
99 version_count = be32_to_cpup(p);
100
101 if (version_count == 0) {
102 ret = -EINVAL;
103 goto out_err_drain_dsaddrs;
104 }
105 dprintk("%s: version count %d\n", __func__, version_count);
106
107 ds_versions = kzalloc_objs(struct nfs4_ff_ds_version, version_count,
108 gfp_flags);
109 if (!ds_versions)
110 goto out_err_drain_dsaddrs;
111
112 for (i = 0; i < version_count; i++) {
113 /* 20 = version(4) + minor_version(4) + rsize(4) + wsize(4) +
114 * tightly_coupled(4) */
115 p = xdr_inline_decode(&stream, 20);
116 if (unlikely(!p))
117 goto out_err_drain_dsaddrs;
118 ds_versions[i].version = be32_to_cpup(p++);
119 ds_versions[i].minor_version = be32_to_cpup(p++);
120 ds_versions[i].rsize = nfs_io_size(be32_to_cpup(p++),
121 server->nfs_client->cl_proto);
122 ds_versions[i].wsize = nfs_io_size(be32_to_cpup(p++),
123 server->nfs_client->cl_proto);
124 ds_versions[i].tightly_coupled = be32_to_cpup(p);
125
126 if (ds_versions[i].rsize > NFS_MAX_FILE_IO_SIZE)
127 ds_versions[i].rsize = NFS_MAX_FILE_IO_SIZE;
128 if (ds_versions[i].wsize > NFS_MAX_FILE_IO_SIZE)
129 ds_versions[i].wsize = NFS_MAX_FILE_IO_SIZE;
130
131 /*
132 * check for valid major/minor combination.
133 * currently we support dataserver which talk:
134 * v3, v4.0, v4.1, v4.2
135 */
136 if (!((ds_versions[i].version == 3 && ds_versions[i].minor_version == 0) ||
137 (ds_versions[i].version == 4 && ds_versions[i].minor_version < 3))) {
138 dprintk("%s: [%d] unsupported ds version %d-%d\n", __func__,
139 i, ds_versions[i].version,
140 ds_versions[i].minor_version);
141 ret = -EPROTONOSUPPORT;
142 goto out_err_drain_dsaddrs;
143 }
144
145 dprintk("%s: [%d] vers %u minor_ver %u rsize %u wsize %u coupled %d\n",
146 __func__, i, ds_versions[i].version,
147 ds_versions[i].minor_version,
148 ds_versions[i].rsize,
149 ds_versions[i].wsize,
150 ds_versions[i].tightly_coupled);
151 }
152
153 new_ds->ds_versions = ds_versions;
154 new_ds->ds_versions_cnt = version_count;
155
156 new_ds->ds = nfs4_pnfs_ds_add(net, &dsaddrs, ds_versions[0].version,
157 gfp_flags);
158 if (!new_ds->ds)
159 goto out_err_drain_dsaddrs;
160
161 /* If DS was already in cache, free ds addrs */
162 while (!list_empty(&dsaddrs)) {
163 da = list_first_entry(&dsaddrs,
164 struct nfs4_pnfs_ds_addr,
165 da_node);
166 list_del_init(&da->da_node);
167 kfree(da->da_remotestr);
168 kfree(da);
169 }
170
171 folio_put(scratch);
172 return new_ds;
173
174out_err_drain_dsaddrs:
175 while (!list_empty(&dsaddrs)) {
176 da = list_first_entry(&dsaddrs, struct nfs4_pnfs_ds_addr,
177 da_node);
178 list_del_init(&da->da_node);
179 kfree(da->da_remotestr);
180 kfree(da);
181 }
182
183 kfree(ds_versions);
184out_scratch:
185 folio_put(scratch);
186out_err:
187 kfree(new_ds);
188
189 dprintk("%s ERROR: returning %d\n", __func__, ret);
190 return NULL;
191}
192
193static void extend_ds_error(struct nfs4_ff_layout_ds_err *err,
194 u64 offset, u64 length)
195{
196 u64 end;
197
198 end = max_t(u64, pnfs_end_offset(err->offset, err->length),
199 pnfs_end_offset(offset, length));
200 err->offset = min_t(u64, err->offset, offset);
201 err->length = end - err->offset;
202}
203
204static int
205ff_ds_error_match(const struct nfs4_ff_layout_ds_err *e1,
206 const struct nfs4_ff_layout_ds_err *e2)
207{
208 int ret;
209
210 if (e1->opnum != e2->opnum)
211 return e1->opnum < e2->opnum ? -1 : 1;
212 if (e1->status != e2->status)
213 return e1->status < e2->status ? -1 : 1;
214 ret = memcmp(e1->stateid.data, e2->stateid.data,
215 sizeof(e1->stateid.data));
216 if (ret != 0)
217 return ret;
218 ret = memcmp(&e1->deviceid, &e2->deviceid, sizeof(e1->deviceid));
219 if (ret != 0)
220 return ret;
221 if (pnfs_end_offset(e1->offset, e1->length) < e2->offset)
222 return -1;
223 if (e1->offset > pnfs_end_offset(e2->offset, e2->length))
224 return 1;
225 /* If ranges overlap or are contiguous, they are the same */
226 return 0;
227}
228
229static void
230ff_layout_add_ds_error_locked(struct nfs4_flexfile_layout *flo,
231 struct nfs4_ff_layout_ds_err *dserr)
232{
233 struct nfs4_ff_layout_ds_err *err, *tmp;
234 struct list_head *head = &flo->error_list;
235 int match;
236
237 /* Do insertion sort w/ merges */
238 list_for_each_entry_safe(err, tmp, &flo->error_list, list) {
239 match = ff_ds_error_match(err, dserr);
240 if (match < 0)
241 continue;
242 if (match > 0) {
243 /* Add entry "dserr" _before_ entry "err" */
244 head = &err->list;
245 break;
246 }
247 /* Entries match, so merge "err" into "dserr" */
248 extend_ds_error(dserr, err->offset, err->length);
249 list_replace(&err->list, &dserr->list);
250 kfree(err);
251 return;
252 }
253
254 list_add_tail(&dserr->list, head);
255}
256
257int ff_layout_track_ds_error(struct nfs4_flexfile_layout *flo,
258 struct nfs4_ff_layout_mirror *mirror,
259 u32 dss_id, u64 offset, u64 length, int status,
260 enum nfs_opnum4 opnum, gfp_t gfp_flags)
261{
262 struct nfs4_ff_layout_ds_err *dserr;
263
264 if (status == 0)
265 return 0;
266
267 if (IS_ERR_OR_NULL(mirror->dss[dss_id].mirror_ds))
268 return -EINVAL;
269
270 dserr = kmalloc_obj(*dserr, gfp_flags);
271 if (!dserr)
272 return -ENOMEM;
273
274 INIT_LIST_HEAD(&dserr->list);
275 dserr->offset = offset;
276 dserr->length = length;
277 dserr->status = status;
278 dserr->opnum = opnum;
279 nfs4_stateid_copy(&dserr->stateid, &mirror->dss[dss_id].stateid);
280 memcpy(&dserr->deviceid, &mirror->dss[dss_id].mirror_ds->id_node.deviceid,
281 NFS4_DEVICEID4_SIZE);
282
283 spin_lock(&flo->generic_hdr.plh_inode->i_lock);
284 ff_layout_add_ds_error_locked(flo, dserr);
285 spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
286 return 0;
287}
288
289static const struct cred *
290ff_layout_get_mirror_cred(struct nfs4_ff_layout_mirror *mirror, u32 iomode, u32 dss_id)
291{
292 const struct cred *cred, __rcu **pcred;
293
294 if (iomode == IOMODE_READ)
295 pcred = &mirror->dss[dss_id].ro_cred;
296 else
297 pcred = &mirror->dss[dss_id].rw_cred;
298
299 rcu_read_lock();
300 do {
301 cred = rcu_dereference(*pcred);
302 if (!cred)
303 break;
304
305 cred = get_cred_rcu(cred);
306 } while(!cred);
307 rcu_read_unlock();
308 return cred;
309}
310
311struct nfs_fh *
312nfs4_ff_layout_select_ds_fh(struct nfs4_ff_layout_mirror *mirror, u32 dss_id)
313{
314 /* FIXME: For now assume there is only 1 version available for the DS */
315 return &mirror->dss[dss_id].fh_versions[0];
316}
317
318void
319nfs4_ff_layout_select_ds_stateid(const struct nfs4_ff_layout_mirror *mirror,
320 u32 dss_id,
321 nfs4_stateid *stateid)
322{
323 if (nfs4_ff_layout_ds_version(mirror, dss_id) == 4)
324 nfs4_stateid_copy(stateid, &mirror->dss[dss_id].stateid);
325}
326
327static bool
328ff_layout_init_mirror_ds(struct pnfs_layout_hdr *lo,
329 struct nfs4_ff_layout_mirror *mirror,
330 u32 dss_id)
331{
332 if (mirror == NULL)
333 goto outerr;
334 if (mirror->dss[dss_id].mirror_ds == NULL) {
335 struct nfs4_deviceid_node *node;
336 struct nfs4_ff_layout_ds *mirror_ds = ERR_PTR(-ENODEV);
337
338 node = nfs4_find_get_deviceid(NFS_SERVER(lo->plh_inode),
339 &mirror->dss[dss_id].devid, lo->plh_lc_cred,
340 GFP_KERNEL);
341 if (node)
342 mirror_ds = FF_LAYOUT_MIRROR_DS(node);
343
344 /* check for race with another call to this function */
345 if (cmpxchg(&mirror->dss[dss_id].mirror_ds, NULL, mirror_ds) &&
346 mirror_ds != ERR_PTR(-ENODEV))
347 nfs4_put_deviceid_node(node);
348 }
349
350 if (IS_ERR(mirror->dss[dss_id].mirror_ds))
351 goto outerr;
352
353 return true;
354outerr:
355 return false;
356}
357
358/**
359 * nfs4_ff_layout_prepare_ds - prepare a DS connection for an RPC call
360 * @lseg: the layout segment we're operating on
361 * @mirror: layout mirror describing the DS to use
362 * @dss_id: DS stripe id to select stripe to use
363 * @fail_return: return layout on connect failure?
364 *
365 * Try to prepare a DS connection to accept an RPC call. This involves
366 * selecting a mirror to use and connecting the client to it if it's not
367 * already connected.
368 *
369 * Since we only need a single functioning mirror to satisfy a read, we don't
370 * want to return the layout if there is one. For writes though, any down
371 * mirror should result in a LAYOUTRETURN. @fail_return is how we distinguish
372 * between the two cases.
373 *
374 * Returns a pointer to a connected DS object on success or NULL on failure.
375 */
376struct nfs4_pnfs_ds *
377nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg,
378 struct nfs4_ff_layout_mirror *mirror,
379 u32 dss_id,
380 bool fail_return)
381{
382 struct nfs4_pnfs_ds *ds;
383 struct inode *ino = lseg->pls_layout->plh_inode;
384 struct nfs_server *s = NFS_SERVER(ino);
385 unsigned int max_payload;
386 int status = -EAGAIN;
387
388 if (!ff_layout_init_mirror_ds(lseg->pls_layout, mirror, dss_id))
389 goto noconnect;
390
391 ds = mirror->dss[dss_id].mirror_ds->ds;
392 if (READ_ONCE(ds->ds_clp))
393 goto out;
394 /* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */
395 smp_rmb();
396
397 /* FIXME: For now we assume the server sent only one version of NFS
398 * to use for the DS.
399 */
400 status = nfs4_pnfs_ds_connect(s, ds, &mirror->dss[dss_id].mirror_ds->id_node,
401 dataserver_timeo, dataserver_retrans,
402 mirror->dss[dss_id].mirror_ds->ds_versions[0].version,
403 mirror->dss[dss_id].mirror_ds->ds_versions[0].minor_version,
404 mirror->dss[dss_id].mirror_ds->ds_versions[0].tightly_coupled);
405
406 /* connect success, check rsize/wsize limit */
407 if (!status) {
408 /*
409 * ds_clp is put in destroy_ds().
410 * keep ds_clp even if DS is local, so that if local IO cannot
411 * proceed somehow, we can fall back to NFS whenever we want.
412 */
413 nfs_local_probe_async(ds->ds_clp);
414 max_payload =
415 nfs_block_size(rpc_max_payload(ds->ds_clp->cl_rpcclient),
416 NULL);
417 if (mirror->dss[dss_id].mirror_ds->ds_versions[0].rsize > max_payload)
418 mirror->dss[dss_id].mirror_ds->ds_versions[0].rsize = max_payload;
419 if (mirror->dss[dss_id].mirror_ds->ds_versions[0].wsize > max_payload)
420 mirror->dss[dss_id].mirror_ds->ds_versions[0].wsize = max_payload;
421 goto out;
422 }
423noconnect:
424 ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout),
425 mirror, dss_id, lseg->pls_range.offset,
426 lseg->pls_range.length, NFS4ERR_NXIO,
427 OP_ILLEGAL, GFP_NOIO);
428 ff_layout_send_layouterror(lseg);
429 if (fail_return || !ff_layout_has_available_ds(lseg))
430 pnfs_error_mark_layout_for_return(ino, lseg);
431 ds = ERR_PTR(status);
432out:
433 return ds;
434}
435
436const struct cred *
437ff_layout_get_ds_cred(struct nfs4_ff_layout_mirror *mirror,
438 const struct pnfs_layout_range *range,
439 const struct cred *mdscred,
440 u32 dss_id)
441{
442 const struct cred *cred;
443
444 if (mirror && !mirror->dss[dss_id].mirror_ds->ds_versions[0].tightly_coupled) {
445 cred = ff_layout_get_mirror_cred(mirror, range->iomode, dss_id);
446 if (!cred)
447 cred = get_cred(mdscred);
448 } else {
449 cred = get_cred(mdscred);
450 }
451 return cred;
452}
453
454/**
455 * nfs4_ff_find_or_create_ds_client - Find or create a DS rpc client
456 * @mirror: pointer to the mirror
457 * @ds_clp: nfs_client for the DS
458 * @inode: pointer to inode
459 * @dss_id: DS stripe id
460 *
461 * Find or create a DS rpc client with th MDS server rpc client auth flavor
462 * in the nfs_client cl_ds_clients list.
463 */
464struct rpc_clnt *
465nfs4_ff_find_or_create_ds_client(struct nfs4_ff_layout_mirror *mirror,
466 struct nfs_client *ds_clp, struct inode *inode,
467 u32 dss_id)
468{
469 switch (mirror->dss[dss_id].mirror_ds->ds_versions[0].version) {
470 case 3:
471 /* For NFSv3 DS, flavor is set when creating DS connections */
472 return ds_clp->cl_rpcclient;
473 case 4:
474 return nfs4_find_or_create_ds_client(ds_clp, inode);
475 default:
476 BUG();
477 }
478}
479
480void ff_layout_free_ds_ioerr(struct list_head *head)
481{
482 struct nfs4_ff_layout_ds_err *err;
483
484 while (!list_empty(head)) {
485 err = list_first_entry(head,
486 struct nfs4_ff_layout_ds_err,
487 list);
488 list_del(&err->list);
489 kfree(err);
490 }
491}
492
493/* called with inode i_lock held */
494int ff_layout_encode_ds_ioerr(struct xdr_stream *xdr, const struct list_head *head)
495{
496 struct nfs4_ff_layout_ds_err *err;
497 __be32 *p;
498
499 list_for_each_entry(err, head, list) {
500 /* offset(8) + length(8) + stateid(NFS4_STATEID_SIZE)
501 * + array length + deviceid(NFS4_DEVICEID4_SIZE)
502 * + status(4) + opnum(4)
503 */
504 p = xdr_reserve_space(xdr,
505 28 + NFS4_STATEID_SIZE + NFS4_DEVICEID4_SIZE);
506 if (unlikely(!p))
507 return -ENOBUFS;
508 p = xdr_encode_hyper(p, err->offset);
509 p = xdr_encode_hyper(p, err->length);
510 p = xdr_encode_opaque_fixed(p, &err->stateid,
511 NFS4_STATEID_SIZE);
512 /* Encode 1 error */
513 *p++ = cpu_to_be32(1);
514 p = xdr_encode_opaque_fixed(p, &err->deviceid,
515 NFS4_DEVICEID4_SIZE);
516 *p++ = cpu_to_be32(err->status);
517 *p++ = cpu_to_be32(err->opnum);
518 dprintk("%s: offset %llu length %llu status %d op %d\n",
519 __func__, err->offset, err->length, err->status,
520 err->opnum);
521 }
522
523 return 0;
524}
525
526static
527unsigned int do_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo,
528 const struct pnfs_layout_range *range,
529 struct list_head *head,
530 unsigned int maxnum)
531{
532 struct nfs4_flexfile_layout *flo = FF_LAYOUT_FROM_HDR(lo);
533 struct inode *inode = lo->plh_inode;
534 struct nfs4_ff_layout_ds_err *err, *n;
535 unsigned int ret = 0;
536
537 spin_lock(&inode->i_lock);
538 list_for_each_entry_safe(err, n, &flo->error_list, list) {
539 if (!pnfs_is_range_intersecting(err->offset,
540 pnfs_end_offset(err->offset, err->length),
541 range->offset,
542 pnfs_end_offset(range->offset, range->length)))
543 continue;
544 if (!maxnum)
545 break;
546 list_move(&err->list, head);
547 maxnum--;
548 ret++;
549 }
550 spin_unlock(&inode->i_lock);
551 return ret;
552}
553
554unsigned int ff_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo,
555 const struct pnfs_layout_range *range,
556 struct list_head *head,
557 unsigned int maxnum)
558{
559 unsigned int ret;
560
561 ret = do_layout_fetch_ds_ioerr(lo, range, head, maxnum);
562 /* If we're over the max, discard all remaining entries */
563 if (ret == maxnum) {
564 LIST_HEAD(discard);
565 do_layout_fetch_ds_ioerr(lo, range, &discard, -1);
566 ff_layout_free_ds_ioerr(&discard);
567 }
568 return ret;
569}
570
571static bool ff_read_layout_has_available_ds(struct pnfs_layout_segment *lseg)
572{
573 struct nfs4_ff_layout_mirror *mirror;
574 struct nfs4_deviceid_node *devid;
575 u32 idx, dss_id;
576
577 for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
578 mirror = FF_LAYOUT_COMP(lseg, idx);
579 if (!mirror)
580 continue;
581 for (dss_id = 0; dss_id < mirror->dss_count; dss_id++) {
582 if (!mirror->dss[dss_id].mirror_ds)
583 return true;
584 if (IS_ERR(mirror->dss[dss_id].mirror_ds))
585 continue;
586 devid = &mirror->dss[dss_id].mirror_ds->id_node;
587 if (!nfs4_test_deviceid_unavailable(devid))
588 return true;
589 }
590 }
591
592 return false;
593}
594
595static bool ff_rw_layout_has_available_ds(struct pnfs_layout_segment *lseg)
596{
597 struct nfs4_ff_layout_mirror *mirror;
598 struct nfs4_deviceid_node *devid;
599 u32 idx, dss_id;
600
601 for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
602 mirror = FF_LAYOUT_COMP(lseg, idx);
603 if (!mirror)
604 return false;
605 for (dss_id = 0; dss_id < mirror->dss_count; dss_id++) {
606 if (IS_ERR(mirror->dss[dss_id].mirror_ds))
607 return false;
608 if (!mirror->dss[dss_id].mirror_ds)
609 continue;
610 devid = &mirror->dss[dss_id].mirror_ds->id_node;
611 if (nfs4_test_deviceid_unavailable(devid))
612 return false;
613 }
614 }
615
616 return FF_LAYOUT_MIRROR_COUNT(lseg) != 0;
617}
618
619static bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg)
620{
621 if (lseg->pls_range.iomode == IOMODE_READ)
622 return ff_read_layout_has_available_ds(lseg);
623 /* Note: RW layout needs all mirrors available */
624 return ff_rw_layout_has_available_ds(lseg);
625}
626
627bool ff_layout_avoid_mds_available_ds(struct pnfs_layout_segment *lseg)
628{
629 return ff_layout_no_fallback_to_mds(lseg) ||
630 ff_layout_has_available_ds(lseg);
631}
632
633bool ff_layout_avoid_read_on_rw(struct pnfs_layout_segment *lseg)
634{
635 return lseg->pls_range.iomode == IOMODE_RW &&
636 ff_layout_no_read_on_rw(lseg);
637}
638
639module_param(dataserver_retrans, uint, 0644);
640MODULE_PARM_DESC(dataserver_retrans, "The number of times the NFSv4.1 client "
641 "retries a request before it attempts further "
642 " recovery action.");
643module_param(dataserver_timeo, uint, 0644);
644MODULE_PARM_DESC(dataserver_timeo, "The time (in tenths of a second) the "
645 "NFSv4.1 client waits for a response from a "
646 " data server before it retries an NFS request.");