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 <bergwolf@primarydata.com> 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 21 static unsigned int dataserver_timeo = NFS_DEF_TCP_RETRANS; 22 static unsigned int dataserver_retrans; 23 24 static bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg); 25 26 void 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 32 void 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 */ 41 struct nfs4_ff_layout_ds * 42 nfs4_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 page *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 u32 mp_count; 53 u32 version_count; 54 __be32 *p; 55 int i, ret = -ENOMEM; 56 57 /* set up xdr stream */ 58 scratch = alloc_page(gfp_flags); 59 if (!scratch) 60 goto out_err; 61 62 new_ds = kzalloc(sizeof(struct nfs4_ff_layout_ds), gfp_flags); 63 if (!new_ds) 64 goto out_scratch; 65 66 nfs4_init_deviceid_node(&new_ds->id_node, 67 server, 68 &pdev->dev_id); 69 INIT_LIST_HEAD(&dsaddrs); 70 71 xdr_init_decode_pages(&stream, &buf, pdev->pages, pdev->pglen); 72 xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE); 73 74 /* multipath count */ 75 p = xdr_inline_decode(&stream, 4); 76 if (unlikely(!p)) 77 goto out_err_drain_dsaddrs; 78 mp_count = be32_to_cpup(p); 79 dprintk("%s: multipath ds count %d\n", __func__, mp_count); 80 81 for (i = 0; i < mp_count; i++) { 82 /* multipath ds */ 83 da = nfs4_decode_mp_ds_addr(server->nfs_client->cl_net, 84 &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 dprintk("%s: version count %d\n", __func__, version_count); 101 102 ds_versions = kzalloc(version_count * sizeof(struct nfs4_ff_ds_version), 103 gfp_flags); 104 if (!ds_versions) 105 goto out_scratch; 106 107 for (i = 0; i < version_count; i++) { 108 /* 20 = version(4) + minor_version(4) + rsize(4) + wsize(4) + 109 * tightly_coupled(4) */ 110 p = xdr_inline_decode(&stream, 20); 111 if (unlikely(!p)) 112 goto out_err_drain_dsaddrs; 113 ds_versions[i].version = be32_to_cpup(p++); 114 ds_versions[i].minor_version = be32_to_cpup(p++); 115 ds_versions[i].rsize = nfs_block_size(be32_to_cpup(p++), NULL); 116 ds_versions[i].wsize = nfs_block_size(be32_to_cpup(p++), NULL); 117 ds_versions[i].tightly_coupled = be32_to_cpup(p); 118 119 if (ds_versions[i].rsize > NFS_MAX_FILE_IO_SIZE) 120 ds_versions[i].rsize = NFS_MAX_FILE_IO_SIZE; 121 if (ds_versions[i].wsize > NFS_MAX_FILE_IO_SIZE) 122 ds_versions[i].wsize = NFS_MAX_FILE_IO_SIZE; 123 124 /* 125 * check for valid major/minor combination. 126 * currently we support dataserver which talk: 127 * v3, v4.0, v4.1, v4.2 128 */ 129 if (!((ds_versions[i].version == 3 && ds_versions[i].minor_version == 0) || 130 (ds_versions[i].version == 4 && ds_versions[i].minor_version < 3))) { 131 dprintk("%s: [%d] unsupported ds version %d-%d\n", __func__, 132 i, ds_versions[i].version, 133 ds_versions[i].minor_version); 134 ret = -EPROTONOSUPPORT; 135 goto out_err_drain_dsaddrs; 136 } 137 138 dprintk("%s: [%d] vers %u minor_ver %u rsize %u wsize %u coupled %d\n", 139 __func__, i, ds_versions[i].version, 140 ds_versions[i].minor_version, 141 ds_versions[i].rsize, 142 ds_versions[i].wsize, 143 ds_versions[i].tightly_coupled); 144 } 145 146 new_ds->ds_versions = ds_versions; 147 new_ds->ds_versions_cnt = version_count; 148 149 new_ds->ds = nfs4_pnfs_ds_add(&dsaddrs, gfp_flags); 150 if (!new_ds->ds) 151 goto out_err_drain_dsaddrs; 152 153 /* If DS was already in cache, free ds addrs */ 154 while (!list_empty(&dsaddrs)) { 155 da = list_first_entry(&dsaddrs, 156 struct nfs4_pnfs_ds_addr, 157 da_node); 158 list_del_init(&da->da_node); 159 kfree(da->da_remotestr); 160 kfree(da); 161 } 162 163 __free_page(scratch); 164 return new_ds; 165 166 out_err_drain_dsaddrs: 167 while (!list_empty(&dsaddrs)) { 168 da = list_first_entry(&dsaddrs, struct nfs4_pnfs_ds_addr, 169 da_node); 170 list_del_init(&da->da_node); 171 kfree(da->da_remotestr); 172 kfree(da); 173 } 174 175 kfree(ds_versions); 176 out_scratch: 177 __free_page(scratch); 178 out_err: 179 kfree(new_ds); 180 181 dprintk("%s ERROR: returning %d\n", __func__, ret); 182 return NULL; 183 } 184 185 static void ff_layout_mark_devid_invalid(struct pnfs_layout_segment *lseg, 186 struct nfs4_deviceid_node *devid) 187 { 188 nfs4_delete_deviceid(devid->ld, devid->nfs_client, &devid->deviceid); 189 if (!ff_layout_has_available_ds(lseg)) 190 pnfs_error_mark_layout_for_return(lseg->pls_layout->plh_inode, 191 lseg); 192 } 193 194 static bool ff_layout_mirror_valid(struct pnfs_layout_segment *lseg, 195 struct nfs4_ff_layout_mirror *mirror, 196 bool create) 197 { 198 if (mirror == NULL || IS_ERR(mirror->mirror_ds)) 199 goto outerr; 200 if (mirror->mirror_ds == NULL) { 201 if (create) { 202 struct nfs4_deviceid_node *node; 203 struct pnfs_layout_hdr *lh = lseg->pls_layout; 204 struct nfs4_ff_layout_ds *mirror_ds = ERR_PTR(-ENODEV); 205 206 node = nfs4_find_get_deviceid(NFS_SERVER(lh->plh_inode), 207 &mirror->devid, lh->plh_lc_cred, 208 GFP_KERNEL); 209 if (node) 210 mirror_ds = FF_LAYOUT_MIRROR_DS(node); 211 212 /* check for race with another call to this function */ 213 if (cmpxchg(&mirror->mirror_ds, NULL, mirror_ds) && 214 mirror_ds != ERR_PTR(-ENODEV)) 215 nfs4_put_deviceid_node(node); 216 } else 217 goto outerr; 218 } 219 220 if (IS_ERR(mirror->mirror_ds)) 221 goto outerr; 222 223 if (mirror->mirror_ds->ds == NULL) { 224 struct nfs4_deviceid_node *devid; 225 devid = &mirror->mirror_ds->id_node; 226 ff_layout_mark_devid_invalid(lseg, devid); 227 return false; 228 } 229 return true; 230 outerr: 231 pnfs_error_mark_layout_for_return(lseg->pls_layout->plh_inode, lseg); 232 return false; 233 } 234 235 static void extend_ds_error(struct nfs4_ff_layout_ds_err *err, 236 u64 offset, u64 length) 237 { 238 u64 end; 239 240 end = max_t(u64, pnfs_end_offset(err->offset, err->length), 241 pnfs_end_offset(offset, length)); 242 err->offset = min_t(u64, err->offset, offset); 243 err->length = end - err->offset; 244 } 245 246 static int 247 ff_ds_error_match(const struct nfs4_ff_layout_ds_err *e1, 248 const struct nfs4_ff_layout_ds_err *e2) 249 { 250 int ret; 251 252 if (e1->opnum != e2->opnum) 253 return e1->opnum < e2->opnum ? -1 : 1; 254 if (e1->status != e2->status) 255 return e1->status < e2->status ? -1 : 1; 256 ret = memcmp(e1->stateid.data, e2->stateid.data, 257 sizeof(e1->stateid.data)); 258 if (ret != 0) 259 return ret; 260 ret = memcmp(&e1->deviceid, &e2->deviceid, sizeof(e1->deviceid)); 261 if (ret != 0) 262 return ret; 263 if (pnfs_end_offset(e1->offset, e1->length) < e2->offset) 264 return -1; 265 if (e1->offset > pnfs_end_offset(e2->offset, e2->length)) 266 return 1; 267 /* If ranges overlap or are contiguous, they are the same */ 268 return 0; 269 } 270 271 static void 272 ff_layout_add_ds_error_locked(struct nfs4_flexfile_layout *flo, 273 struct nfs4_ff_layout_ds_err *dserr) 274 { 275 struct nfs4_ff_layout_ds_err *err, *tmp; 276 struct list_head *head = &flo->error_list; 277 int match; 278 279 /* Do insertion sort w/ merges */ 280 list_for_each_entry_safe(err, tmp, &flo->error_list, list) { 281 match = ff_ds_error_match(err, dserr); 282 if (match < 0) 283 continue; 284 if (match > 0) { 285 /* Add entry "dserr" _before_ entry "err" */ 286 head = &err->list; 287 break; 288 } 289 /* Entries match, so merge "err" into "dserr" */ 290 extend_ds_error(dserr, err->offset, err->length); 291 list_replace(&err->list, &dserr->list); 292 kfree(err); 293 return; 294 } 295 296 list_add_tail(&dserr->list, head); 297 } 298 299 int ff_layout_track_ds_error(struct nfs4_flexfile_layout *flo, 300 struct nfs4_ff_layout_mirror *mirror, u64 offset, 301 u64 length, int status, enum nfs_opnum4 opnum, 302 gfp_t gfp_flags) 303 { 304 struct nfs4_ff_layout_ds_err *dserr; 305 306 if (status == 0) 307 return 0; 308 309 if (mirror->mirror_ds == NULL) 310 return -EINVAL; 311 312 dserr = kmalloc(sizeof(*dserr), gfp_flags); 313 if (!dserr) 314 return -ENOMEM; 315 316 INIT_LIST_HEAD(&dserr->list); 317 dserr->offset = offset; 318 dserr->length = length; 319 dserr->status = status; 320 dserr->opnum = opnum; 321 nfs4_stateid_copy(&dserr->stateid, &mirror->stateid); 322 memcpy(&dserr->deviceid, &mirror->mirror_ds->id_node.deviceid, 323 NFS4_DEVICEID4_SIZE); 324 325 spin_lock(&flo->generic_hdr.plh_inode->i_lock); 326 ff_layout_add_ds_error_locked(flo, dserr); 327 spin_unlock(&flo->generic_hdr.plh_inode->i_lock); 328 329 return 0; 330 } 331 332 static struct rpc_cred * 333 ff_layout_get_mirror_cred(struct nfs4_ff_layout_mirror *mirror, u32 iomode) 334 { 335 struct rpc_cred *cred, __rcu **pcred; 336 337 if (iomode == IOMODE_READ) 338 pcred = &mirror->ro_cred; 339 else 340 pcred = &mirror->rw_cred; 341 342 rcu_read_lock(); 343 do { 344 cred = rcu_dereference(*pcred); 345 if (!cred) 346 break; 347 348 cred = get_rpccred_rcu(cred); 349 } while(!cred); 350 rcu_read_unlock(); 351 return cred; 352 } 353 354 struct nfs_fh * 355 nfs4_ff_layout_select_ds_fh(struct pnfs_layout_segment *lseg, u32 mirror_idx) 356 { 357 struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, mirror_idx); 358 struct nfs_fh *fh = NULL; 359 360 if (!ff_layout_mirror_valid(lseg, mirror, false)) { 361 pr_err_ratelimited("NFS: %s: No data server for mirror offset index %d\n", 362 __func__, mirror_idx); 363 goto out; 364 } 365 366 /* FIXME: For now assume there is only 1 version available for the DS */ 367 fh = &mirror->fh_versions[0]; 368 out: 369 return fh; 370 } 371 372 /** 373 * nfs4_ff_layout_prepare_ds - prepare a DS connection for an RPC call 374 * @lseg: the layout segment we're operating on 375 * @ds_idx: index of the DS to use 376 * @fail_return: return layout on connect failure? 377 * 378 * Try to prepare a DS connection to accept an RPC call. This involves 379 * selecting a mirror to use and connecting the client to it if it's not 380 * already connected. 381 * 382 * Since we only need a single functioning mirror to satisfy a read, we don't 383 * want to return the layout if there is one. For writes though, any down 384 * mirror should result in a LAYOUTRETURN. @fail_return is how we distinguish 385 * between the two cases. 386 * 387 * Returns a pointer to a connected DS object on success or NULL on failure. 388 */ 389 struct nfs4_pnfs_ds * 390 nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx, 391 bool fail_return) 392 { 393 struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx); 394 struct nfs4_pnfs_ds *ds = NULL; 395 struct nfs4_deviceid_node *devid; 396 struct inode *ino = lseg->pls_layout->plh_inode; 397 struct nfs_server *s = NFS_SERVER(ino); 398 unsigned int max_payload; 399 int status; 400 401 if (!ff_layout_mirror_valid(lseg, mirror, true)) { 402 pr_err_ratelimited("NFS: %s: No data server for offset index %d\n", 403 __func__, ds_idx); 404 goto out; 405 } 406 407 devid = &mirror->mirror_ds->id_node; 408 if (ff_layout_test_devid_unavailable(devid)) 409 goto out_fail; 410 411 ds = mirror->mirror_ds->ds; 412 /* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */ 413 smp_rmb(); 414 if (ds->ds_clp) 415 goto out; 416 417 /* FIXME: For now we assume the server sent only one version of NFS 418 * to use for the DS. 419 */ 420 status = nfs4_pnfs_ds_connect(s, ds, devid, dataserver_timeo, 421 dataserver_retrans, 422 mirror->mirror_ds->ds_versions[0].version, 423 mirror->mirror_ds->ds_versions[0].minor_version); 424 425 /* connect success, check rsize/wsize limit */ 426 if (!status) { 427 max_payload = 428 nfs_block_size(rpc_max_payload(ds->ds_clp->cl_rpcclient), 429 NULL); 430 if (mirror->mirror_ds->ds_versions[0].rsize > max_payload) 431 mirror->mirror_ds->ds_versions[0].rsize = max_payload; 432 if (mirror->mirror_ds->ds_versions[0].wsize > max_payload) 433 mirror->mirror_ds->ds_versions[0].wsize = max_payload; 434 goto out; 435 } 436 out_fail: 437 ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout), 438 mirror, lseg->pls_range.offset, 439 lseg->pls_range.length, NFS4ERR_NXIO, 440 OP_ILLEGAL, GFP_NOIO); 441 if (fail_return || !ff_layout_has_available_ds(lseg)) 442 pnfs_error_mark_layout_for_return(ino, lseg); 443 ds = NULL; 444 out: 445 return ds; 446 } 447 448 struct rpc_cred * 449 ff_layout_get_ds_cred(struct pnfs_layout_segment *lseg, u32 ds_idx, 450 struct rpc_cred *mdscred) 451 { 452 struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx); 453 struct rpc_cred *cred; 454 455 if (mirror) { 456 cred = ff_layout_get_mirror_cred(mirror, lseg->pls_range.iomode); 457 if (!cred) 458 cred = get_rpccred(mdscred); 459 } else { 460 cred = get_rpccred(mdscred); 461 } 462 return cred; 463 } 464 465 /** 466 * Find or create a DS rpc client with th MDS server rpc client auth flavor 467 * in the nfs_client cl_ds_clients list. 468 */ 469 struct rpc_clnt * 470 nfs4_ff_find_or_create_ds_client(struct pnfs_layout_segment *lseg, u32 ds_idx, 471 struct nfs_client *ds_clp, struct inode *inode) 472 { 473 struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx); 474 475 switch (mirror->mirror_ds->ds_versions[0].version) { 476 case 3: 477 /* For NFSv3 DS, flavor is set when creating DS connections */ 478 return ds_clp->cl_rpcclient; 479 case 4: 480 return nfs4_find_or_create_ds_client(ds_clp, inode); 481 default: 482 BUG(); 483 } 484 } 485 486 void ff_layout_free_ds_ioerr(struct list_head *head) 487 { 488 struct nfs4_ff_layout_ds_err *err; 489 490 while (!list_empty(head)) { 491 err = list_first_entry(head, 492 struct nfs4_ff_layout_ds_err, 493 list); 494 list_del(&err->list); 495 kfree(err); 496 } 497 } 498 499 /* called with inode i_lock held */ 500 int ff_layout_encode_ds_ioerr(struct xdr_stream *xdr, const struct list_head *head) 501 { 502 struct nfs4_ff_layout_ds_err *err; 503 __be32 *p; 504 505 list_for_each_entry(err, head, list) { 506 /* offset(8) + length(8) + stateid(NFS4_STATEID_SIZE) 507 * + array length + deviceid(NFS4_DEVICEID4_SIZE) 508 * + status(4) + opnum(4) 509 */ 510 p = xdr_reserve_space(xdr, 511 28 + NFS4_STATEID_SIZE + NFS4_DEVICEID4_SIZE); 512 if (unlikely(!p)) 513 return -ENOBUFS; 514 p = xdr_encode_hyper(p, err->offset); 515 p = xdr_encode_hyper(p, err->length); 516 p = xdr_encode_opaque_fixed(p, &err->stateid, 517 NFS4_STATEID_SIZE); 518 /* Encode 1 error */ 519 *p++ = cpu_to_be32(1); 520 p = xdr_encode_opaque_fixed(p, &err->deviceid, 521 NFS4_DEVICEID4_SIZE); 522 *p++ = cpu_to_be32(err->status); 523 *p++ = cpu_to_be32(err->opnum); 524 dprintk("%s: offset %llu length %llu status %d op %d\n", 525 __func__, err->offset, err->length, err->status, 526 err->opnum); 527 } 528 529 return 0; 530 } 531 532 static 533 unsigned int do_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo, 534 const struct pnfs_layout_range *range, 535 struct list_head *head, 536 unsigned int maxnum) 537 { 538 struct nfs4_flexfile_layout *flo = FF_LAYOUT_FROM_HDR(lo); 539 struct inode *inode = lo->plh_inode; 540 struct nfs4_ff_layout_ds_err *err, *n; 541 unsigned int ret = 0; 542 543 spin_lock(&inode->i_lock); 544 list_for_each_entry_safe(err, n, &flo->error_list, list) { 545 if (!pnfs_is_range_intersecting(err->offset, 546 pnfs_end_offset(err->offset, err->length), 547 range->offset, 548 pnfs_end_offset(range->offset, range->length))) 549 continue; 550 if (!maxnum) 551 break; 552 list_move(&err->list, head); 553 maxnum--; 554 ret++; 555 } 556 spin_unlock(&inode->i_lock); 557 return ret; 558 } 559 560 unsigned int ff_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo, 561 const struct pnfs_layout_range *range, 562 struct list_head *head, 563 unsigned int maxnum) 564 { 565 unsigned int ret; 566 567 ret = do_layout_fetch_ds_ioerr(lo, range, head, maxnum); 568 /* If we're over the max, discard all remaining entries */ 569 if (ret == maxnum) { 570 LIST_HEAD(discard); 571 do_layout_fetch_ds_ioerr(lo, range, &discard, -1); 572 ff_layout_free_ds_ioerr(&discard); 573 } 574 return ret; 575 } 576 577 static bool ff_read_layout_has_available_ds(struct pnfs_layout_segment *lseg) 578 { 579 struct nfs4_ff_layout_mirror *mirror; 580 struct nfs4_deviceid_node *devid; 581 u32 idx; 582 583 for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) { 584 mirror = FF_LAYOUT_COMP(lseg, idx); 585 if (mirror) { 586 if (!mirror->mirror_ds) 587 return true; 588 if (IS_ERR(mirror->mirror_ds)) 589 continue; 590 devid = &mirror->mirror_ds->id_node; 591 if (!ff_layout_test_devid_unavailable(devid)) 592 return true; 593 } 594 } 595 596 return false; 597 } 598 599 static bool ff_rw_layout_has_available_ds(struct pnfs_layout_segment *lseg) 600 { 601 struct nfs4_ff_layout_mirror *mirror; 602 struct nfs4_deviceid_node *devid; 603 u32 idx; 604 605 for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) { 606 mirror = FF_LAYOUT_COMP(lseg, idx); 607 if (!mirror || IS_ERR(mirror->mirror_ds)) 608 return false; 609 if (!mirror->mirror_ds) 610 continue; 611 devid = &mirror->mirror_ds->id_node; 612 if (ff_layout_test_devid_unavailable(devid)) 613 return false; 614 } 615 616 return FF_LAYOUT_MIRROR_COUNT(lseg) != 0; 617 } 618 619 static 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 } 626 627 bool 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 } 632 633 bool 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 } 638 639 module_param(dataserver_retrans, uint, 0644); 640 MODULE_PARM_DESC(dataserver_retrans, "The number of times the NFSv4.1 client " 641 "retries a request before it attempts further " 642 " recovery action."); 643 module_param(dataserver_timeo, uint, 0644); 644 MODULE_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."); 647