fs/nfs/flexfilelayout/flexfilelayoutdev.c

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