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_TIMEO; 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 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, gfp_flags); 157 if (!new_ds->ds) 158 goto out_err_drain_dsaddrs; 159 160 /* If DS was already in cache, free ds addrs */ 161 while (!list_empty(&dsaddrs)) { 162 da = list_first_entry(&dsaddrs, 163 struct nfs4_pnfs_ds_addr, 164 da_node); 165 list_del_init(&da->da_node); 166 kfree(da->da_remotestr); 167 kfree(da); 168 } 169 170 folio_put(scratch); 171 return new_ds; 172 173 out_err_drain_dsaddrs: 174 while (!list_empty(&dsaddrs)) { 175 da = list_first_entry(&dsaddrs, struct nfs4_pnfs_ds_addr, 176 da_node); 177 list_del_init(&da->da_node); 178 kfree(da->da_remotestr); 179 kfree(da); 180 } 181 182 kfree(ds_versions); 183 out_scratch: 184 folio_put(scratch); 185 out_err: 186 kfree(new_ds); 187 188 dprintk("%s ERROR: returning %d\n", __func__, ret); 189 return NULL; 190 } 191 192 static void extend_ds_error(struct nfs4_ff_layout_ds_err *err, 193 u64 offset, u64 length) 194 { 195 u64 end; 196 197 end = max_t(u64, pnfs_end_offset(err->offset, err->length), 198 pnfs_end_offset(offset, length)); 199 err->offset = min_t(u64, err->offset, offset); 200 err->length = end - err->offset; 201 } 202 203 static int 204 ff_ds_error_match(const struct nfs4_ff_layout_ds_err *e1, 205 const struct nfs4_ff_layout_ds_err *e2) 206 { 207 int ret; 208 209 if (e1->opnum != e2->opnum) 210 return e1->opnum < e2->opnum ? -1 : 1; 211 if (e1->status != e2->status) 212 return e1->status < e2->status ? -1 : 1; 213 ret = memcmp(e1->stateid.data, e2->stateid.data, 214 sizeof(e1->stateid.data)); 215 if (ret != 0) 216 return ret; 217 ret = memcmp(&e1->deviceid, &e2->deviceid, sizeof(e1->deviceid)); 218 if (ret != 0) 219 return ret; 220 if (pnfs_end_offset(e1->offset, e1->length) < e2->offset) 221 return -1; 222 if (e1->offset > pnfs_end_offset(e2->offset, e2->length)) 223 return 1; 224 /* If ranges overlap or are contiguous, they are the same */ 225 return 0; 226 } 227 228 static void 229 ff_layout_add_ds_error_locked(struct nfs4_flexfile_layout *flo, 230 struct nfs4_ff_layout_ds_err *dserr) 231 { 232 struct nfs4_ff_layout_ds_err *err, *tmp; 233 struct list_head *head = &flo->error_list; 234 int match; 235 236 /* Do insertion sort w/ merges */ 237 list_for_each_entry_safe(err, tmp, &flo->error_list, list) { 238 match = ff_ds_error_match(err, dserr); 239 if (match < 0) 240 continue; 241 if (match > 0) { 242 /* Add entry "dserr" _before_ entry "err" */ 243 head = &err->list; 244 break; 245 } 246 /* Entries match, so merge "err" into "dserr" */ 247 extend_ds_error(dserr, err->offset, err->length); 248 list_replace(&err->list, &dserr->list); 249 kfree(err); 250 return; 251 } 252 253 list_add_tail(&dserr->list, head); 254 } 255 256 int ff_layout_track_ds_error(struct nfs4_flexfile_layout *flo, 257 struct nfs4_ff_layout_mirror *mirror, 258 u32 dss_id, u64 offset, u64 length, int status, 259 enum nfs_opnum4 opnum, gfp_t gfp_flags) 260 { 261 struct nfs4_ff_layout_ds_err *dserr; 262 263 if (status == 0) 264 return 0; 265 266 if (IS_ERR_OR_NULL(mirror->dss[dss_id].mirror_ds)) 267 return -EINVAL; 268 269 dserr = kmalloc_obj(*dserr, gfp_flags); 270 if (!dserr) 271 return -ENOMEM; 272 273 INIT_LIST_HEAD(&dserr->list); 274 dserr->offset = offset; 275 dserr->length = length; 276 dserr->status = status; 277 dserr->opnum = opnum; 278 nfs4_stateid_copy(&dserr->stateid, &mirror->dss[dss_id].stateid); 279 memcpy(&dserr->deviceid, &mirror->dss[dss_id].mirror_ds->id_node.deviceid, 280 NFS4_DEVICEID4_SIZE); 281 282 spin_lock(&flo->generic_hdr.plh_inode->i_lock); 283 ff_layout_add_ds_error_locked(flo, dserr); 284 spin_unlock(&flo->generic_hdr.plh_inode->i_lock); 285 return 0; 286 } 287 288 static const struct cred * 289 ff_layout_get_mirror_cred(struct nfs4_ff_layout_mirror *mirror, u32 iomode, u32 dss_id) 290 { 291 const struct cred *cred, __rcu **pcred; 292 293 if (iomode == IOMODE_READ) 294 pcred = &mirror->dss[dss_id].ro_cred; 295 else 296 pcred = &mirror->dss[dss_id].rw_cred; 297 298 rcu_read_lock(); 299 do { 300 cred = rcu_dereference(*pcred); 301 if (!cred) 302 break; 303 304 cred = get_cred_rcu(cred); 305 } while(!cred); 306 rcu_read_unlock(); 307 return cred; 308 } 309 310 struct nfs_fh * 311 nfs4_ff_layout_select_ds_fh(struct nfs4_ff_layout_mirror *mirror, u32 dss_id) 312 { 313 /* FIXME: For now assume there is only 1 version available for the DS */ 314 return &mirror->dss[dss_id].fh_versions[0]; 315 } 316 317 void 318 nfs4_ff_layout_select_ds_stateid(const struct nfs4_ff_layout_mirror *mirror, 319 u32 dss_id, 320 nfs4_stateid *stateid) 321 { 322 if (nfs4_ff_layout_ds_version(mirror, dss_id) == 4) 323 nfs4_stateid_copy(stateid, &mirror->dss[dss_id].stateid); 324 } 325 326 static bool 327 ff_layout_init_mirror_ds(struct pnfs_layout_hdr *lo, 328 struct nfs4_ff_layout_mirror *mirror, 329 u32 dss_id) 330 { 331 if (mirror == NULL) 332 goto outerr; 333 if (mirror->dss[dss_id].mirror_ds == NULL) { 334 struct nfs4_deviceid_node *node; 335 struct nfs4_ff_layout_ds *mirror_ds = ERR_PTR(-ENODEV); 336 337 node = nfs4_find_get_deviceid(NFS_SERVER(lo->plh_inode), 338 &mirror->dss[dss_id].devid, lo->plh_lc_cred, 339 GFP_KERNEL); 340 if (node) 341 mirror_ds = FF_LAYOUT_MIRROR_DS(node); 342 343 /* check for race with another call to this function */ 344 if (cmpxchg(&mirror->dss[dss_id].mirror_ds, NULL, mirror_ds) && 345 mirror_ds != ERR_PTR(-ENODEV)) 346 nfs4_put_deviceid_node(node); 347 } 348 349 if (IS_ERR(mirror->dss[dss_id].mirror_ds)) 350 goto outerr; 351 352 return true; 353 outerr: 354 return false; 355 } 356 357 /** 358 * nfs4_ff_layout_prepare_ds - prepare a DS connection for an RPC call 359 * @lseg: the layout segment we're operating on 360 * @mirror: layout mirror describing the DS to use 361 * @dss_id: DS stripe id to select stripe to use 362 * @fail_return: return layout on connect failure? 363 * 364 * Try to prepare a DS connection to accept an RPC call. This involves 365 * selecting a mirror to use and connecting the client to it if it's not 366 * already connected. 367 * 368 * Since we only need a single functioning mirror to satisfy a read, we don't 369 * want to return the layout if there is one. For writes though, any down 370 * mirror should result in a LAYOUTRETURN. @fail_return is how we distinguish 371 * between the two cases. 372 * 373 * Returns a pointer to a connected DS object on success or NULL on failure. 374 */ 375 struct nfs4_pnfs_ds * 376 nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, 377 struct nfs4_ff_layout_mirror *mirror, 378 u32 dss_id, 379 bool fail_return) 380 { 381 struct nfs4_pnfs_ds *ds; 382 struct inode *ino = lseg->pls_layout->plh_inode; 383 struct nfs_server *s = NFS_SERVER(ino); 384 unsigned int max_payload; 385 int status = -EAGAIN; 386 387 if (!ff_layout_init_mirror_ds(lseg->pls_layout, mirror, dss_id)) 388 goto noconnect; 389 390 ds = mirror->dss[dss_id].mirror_ds->ds; 391 if (READ_ONCE(ds->ds_clp)) 392 goto out; 393 /* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */ 394 smp_rmb(); 395 396 /* FIXME: For now we assume the server sent only one version of NFS 397 * to use for the DS. 398 */ 399 status = nfs4_pnfs_ds_connect(s, ds, &mirror->dss[dss_id].mirror_ds->id_node, 400 dataserver_timeo, dataserver_retrans, 401 mirror->dss[dss_id].mirror_ds->ds_versions[0].version, 402 mirror->dss[dss_id].mirror_ds->ds_versions[0].minor_version); 403 404 /* connect success, check rsize/wsize limit */ 405 if (!status) { 406 /* 407 * ds_clp is put in destroy_ds(). 408 * keep ds_clp even if DS is local, so that if local IO cannot 409 * proceed somehow, we can fall back to NFS whenever we want. 410 */ 411 nfs_local_probe_async(ds->ds_clp); 412 max_payload = 413 nfs_block_size(rpc_max_payload(ds->ds_clp->cl_rpcclient), 414 NULL); 415 if (mirror->dss[dss_id].mirror_ds->ds_versions[0].rsize > max_payload) 416 mirror->dss[dss_id].mirror_ds->ds_versions[0].rsize = max_payload; 417 if (mirror->dss[dss_id].mirror_ds->ds_versions[0].wsize > max_payload) 418 mirror->dss[dss_id].mirror_ds->ds_versions[0].wsize = max_payload; 419 goto out; 420 } 421 noconnect: 422 ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout), 423 mirror, dss_id, lseg->pls_range.offset, 424 lseg->pls_range.length, NFS4ERR_NXIO, 425 OP_ILLEGAL, GFP_NOIO); 426 ff_layout_send_layouterror(lseg); 427 if (fail_return || !ff_layout_has_available_ds(lseg)) 428 pnfs_error_mark_layout_for_return(ino, lseg); 429 ds = ERR_PTR(status); 430 out: 431 return ds; 432 } 433 434 const struct cred * 435 ff_layout_get_ds_cred(struct nfs4_ff_layout_mirror *mirror, 436 const struct pnfs_layout_range *range, 437 const struct cred *mdscred, 438 u32 dss_id) 439 { 440 const struct cred *cred; 441 442 if (mirror && !mirror->dss[dss_id].mirror_ds->ds_versions[0].tightly_coupled) { 443 cred = ff_layout_get_mirror_cred(mirror, range->iomode, dss_id); 444 if (!cred) 445 cred = get_cred(mdscred); 446 } else { 447 cred = get_cred(mdscred); 448 } 449 return cred; 450 } 451 452 /** 453 * nfs4_ff_find_or_create_ds_client - Find or create a DS rpc client 454 * @mirror: pointer to the mirror 455 * @ds_clp: nfs_client for the DS 456 * @inode: pointer to inode 457 * @dss_id: DS stripe id 458 * 459 * Find or create a DS rpc client with th MDS server rpc client auth flavor 460 * in the nfs_client cl_ds_clients list. 461 */ 462 struct rpc_clnt * 463 nfs4_ff_find_or_create_ds_client(struct nfs4_ff_layout_mirror *mirror, 464 struct nfs_client *ds_clp, struct inode *inode, 465 u32 dss_id) 466 { 467 switch (mirror->dss[dss_id].mirror_ds->ds_versions[0].version) { 468 case 3: 469 /* For NFSv3 DS, flavor is set when creating DS connections */ 470 return ds_clp->cl_rpcclient; 471 case 4: 472 return nfs4_find_or_create_ds_client(ds_clp, inode); 473 default: 474 BUG(); 475 } 476 } 477 478 void ff_layout_free_ds_ioerr(struct list_head *head) 479 { 480 struct nfs4_ff_layout_ds_err *err; 481 482 while (!list_empty(head)) { 483 err = list_first_entry(head, 484 struct nfs4_ff_layout_ds_err, 485 list); 486 list_del(&err->list); 487 kfree(err); 488 } 489 } 490 491 /* called with inode i_lock held */ 492 int ff_layout_encode_ds_ioerr(struct xdr_stream *xdr, const struct list_head *head) 493 { 494 struct nfs4_ff_layout_ds_err *err; 495 __be32 *p; 496 497 list_for_each_entry(err, head, list) { 498 /* offset(8) + length(8) + stateid(NFS4_STATEID_SIZE) 499 * + array length + deviceid(NFS4_DEVICEID4_SIZE) 500 * + status(4) + opnum(4) 501 */ 502 p = xdr_reserve_space(xdr, 503 28 + NFS4_STATEID_SIZE + NFS4_DEVICEID4_SIZE); 504 if (unlikely(!p)) 505 return -ENOBUFS; 506 p = xdr_encode_hyper(p, err->offset); 507 p = xdr_encode_hyper(p, err->length); 508 p = xdr_encode_opaque_fixed(p, &err->stateid, 509 NFS4_STATEID_SIZE); 510 /* Encode 1 error */ 511 *p++ = cpu_to_be32(1); 512 p = xdr_encode_opaque_fixed(p, &err->deviceid, 513 NFS4_DEVICEID4_SIZE); 514 *p++ = cpu_to_be32(err->status); 515 *p++ = cpu_to_be32(err->opnum); 516 dprintk("%s: offset %llu length %llu status %d op %d\n", 517 __func__, err->offset, err->length, err->status, 518 err->opnum); 519 } 520 521 return 0; 522 } 523 524 static 525 unsigned int do_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo, 526 const struct pnfs_layout_range *range, 527 struct list_head *head, 528 unsigned int maxnum) 529 { 530 struct nfs4_flexfile_layout *flo = FF_LAYOUT_FROM_HDR(lo); 531 struct inode *inode = lo->plh_inode; 532 struct nfs4_ff_layout_ds_err *err, *n; 533 unsigned int ret = 0; 534 535 spin_lock(&inode->i_lock); 536 list_for_each_entry_safe(err, n, &flo->error_list, list) { 537 if (!pnfs_is_range_intersecting(err->offset, 538 pnfs_end_offset(err->offset, err->length), 539 range->offset, 540 pnfs_end_offset(range->offset, range->length))) 541 continue; 542 if (!maxnum) 543 break; 544 list_move(&err->list, head); 545 maxnum--; 546 ret++; 547 } 548 spin_unlock(&inode->i_lock); 549 return ret; 550 } 551 552 unsigned int ff_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo, 553 const struct pnfs_layout_range *range, 554 struct list_head *head, 555 unsigned int maxnum) 556 { 557 unsigned int ret; 558 559 ret = do_layout_fetch_ds_ioerr(lo, range, head, maxnum); 560 /* If we're over the max, discard all remaining entries */ 561 if (ret == maxnum) { 562 LIST_HEAD(discard); 563 do_layout_fetch_ds_ioerr(lo, range, &discard, -1); 564 ff_layout_free_ds_ioerr(&discard); 565 } 566 return ret; 567 } 568 569 static bool ff_read_layout_has_available_ds(struct pnfs_layout_segment *lseg) 570 { 571 struct nfs4_ff_layout_mirror *mirror; 572 struct nfs4_deviceid_node *devid; 573 u32 idx, dss_id; 574 575 for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) { 576 mirror = FF_LAYOUT_COMP(lseg, idx); 577 if (!mirror) 578 continue; 579 for (dss_id = 0; dss_id < mirror->dss_count; dss_id++) { 580 if (!mirror->dss[dss_id].mirror_ds) 581 return true; 582 if (IS_ERR(mirror->dss[dss_id].mirror_ds)) 583 continue; 584 devid = &mirror->dss[dss_id].mirror_ds->id_node; 585 if (!nfs4_test_deviceid_unavailable(devid)) 586 return true; 587 } 588 } 589 590 return false; 591 } 592 593 static bool ff_rw_layout_has_available_ds(struct pnfs_layout_segment *lseg) 594 { 595 struct nfs4_ff_layout_mirror *mirror; 596 struct nfs4_deviceid_node *devid; 597 u32 idx, dss_id; 598 599 for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) { 600 mirror = FF_LAYOUT_COMP(lseg, idx); 601 if (!mirror) 602 return false; 603 for (dss_id = 0; dss_id < mirror->dss_count; dss_id++) { 604 if (IS_ERR(mirror->dss[dss_id].mirror_ds)) 605 return false; 606 if (!mirror->dss[dss_id].mirror_ds) 607 continue; 608 devid = &mirror->dss[dss_id].mirror_ds->id_node; 609 if (nfs4_test_deviceid_unavailable(devid)) 610 return false; 611 } 612 } 613 614 return FF_LAYOUT_MIRROR_COUNT(lseg) != 0; 615 } 616 617 static bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg) 618 { 619 if (lseg->pls_range.iomode == IOMODE_READ) 620 return ff_read_layout_has_available_ds(lseg); 621 /* Note: RW layout needs all mirrors available */ 622 return ff_rw_layout_has_available_ds(lseg); 623 } 624 625 bool ff_layout_avoid_mds_available_ds(struct pnfs_layout_segment *lseg) 626 { 627 return ff_layout_no_fallback_to_mds(lseg) || 628 ff_layout_has_available_ds(lseg); 629 } 630 631 bool ff_layout_avoid_read_on_rw(struct pnfs_layout_segment *lseg) 632 { 633 return lseg->pls_range.iomode == IOMODE_RW && 634 ff_layout_no_read_on_rw(lseg); 635 } 636 637 module_param(dataserver_retrans, uint, 0644); 638 MODULE_PARM_DESC(dataserver_retrans, "The number of times the NFSv4.1 client " 639 "retries a request before it attempts further " 640 " recovery action."); 641 module_param(dataserver_timeo, uint, 0644); 642 MODULE_PARM_DESC(dataserver_timeo, "The time (in tenths of a second) the " 643 "NFSv4.1 client waits for a response from a " 644 " data server before it retries an NFS request."); 645