fs/nfs/flexfilelayout/flexfilelayoutdev.c

   1 /*
   2  * Device operations for the pnfs nfs4 file layout driver.
   3  *
   4  * Copyright (c) 2014, Primary Data, Inc. All rights reserved.
   5  *
   6  * Tao Peng <bergwolf@primarydata.com>
   7  */
   8
   9 #include <linux/nfs_fs.h>
  10 #include <linux/vmalloc.h>
  11 #include <linux/module.h>
  12 #include <linux/sunrpc/addr.h>
  13
  14 #include "../internal.h"
  15 #include "../nfs4session.h"
  16 #include "flexfilelayout.h"
  17
  18 #define NFSDBG_FACILITY         NFSDBG_PNFS_LD
  19
  20 static unsigned int dataserver_timeo = NFS4_DEF_DS_TIMEO;
  21 static unsigned int dataserver_retrans = NFS4_DEF_DS_RETRANS;
  22
  23 void nfs4_ff_layout_put_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
  24 {
  25         if (mirror_ds)
  26                 nfs4_put_deviceid_node(&mirror_ds->id_node);
  27 }
  28
  29 void nfs4_ff_layout_free_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
  30 {
  31         nfs4_print_deviceid(&mirror_ds->id_node.deviceid);
  32         nfs4_pnfs_ds_put(mirror_ds->ds);
  33         kfree(mirror_ds->ds_versions);
  34         kfree_rcu(mirror_ds, id_node.rcu);
  35 }
  36
  37 /* Decode opaque device data and construct new_ds using it */
  38 struct nfs4_ff_layout_ds *
  39 nfs4_ff_alloc_deviceid_node(struct nfs_server *server, struct pnfs_device *pdev,
  40                             gfp_t gfp_flags)
  41 {
  42         struct xdr_stream stream;
  43         struct xdr_buf buf;
  44         struct page *scratch;
  45         struct list_head dsaddrs;
  46         struct nfs4_pnfs_ds_addr *da;
  47         struct nfs4_ff_layout_ds *new_ds = NULL;
  48         struct nfs4_ff_ds_version *ds_versions = NULL;
  49         u32 mp_count;
  50         u32 version_count;
  51         __be32 *p;
  52         int i, ret = -ENOMEM;
  53
  54         /* set up xdr stream */
  55         scratch = alloc_page(gfp_flags);
  56         if (!scratch)
  57                 goto out_err;
  58
  59         new_ds = kzalloc(sizeof(struct nfs4_ff_layout_ds), gfp_flags);
  60         if (!new_ds)
  61                 goto out_scratch;
  62
  63         nfs4_init_deviceid_node(&new_ds->id_node,
  64                                 server,
  65                                 &pdev->dev_id);
  66         INIT_LIST_HEAD(&dsaddrs);
  67
  68         xdr_init_decode_pages(&stream, &buf, pdev->pages, pdev->pglen);
  69         xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE);
  70
  71         /* multipath count */
  72         p = xdr_inline_decode(&stream, 4);
  73         if (unlikely(!p))
  74                 goto out_err_drain_dsaddrs;
  75         mp_count = be32_to_cpup(p);
  76         dprintk("%s: multipath ds count %d\n", __func__, mp_count);
  77
  78         for (i = 0; i < mp_count; i++) {
  79                 /* multipath ds */
  80                 da = nfs4_decode_mp_ds_addr(server->nfs_client->cl_net,
  81                                             &stream, gfp_flags);
  82                 if (da)
  83                         list_add_tail(&da->da_node, &dsaddrs);
  84         }
  85         if (list_empty(&dsaddrs)) {
  86                 dprintk("%s: no suitable DS addresses found\n",
  87                         __func__);
  88                 ret = -ENOMEDIUM;
  89                 goto out_err_drain_dsaddrs;
  90         }
  91
  92         /* version count */
  93         p = xdr_inline_decode(&stream, 4);
  94         if (unlikely(!p))
  95                 goto out_err_drain_dsaddrs;
  96         version_count = be32_to_cpup(p);
  97         dprintk("%s: version count %d\n", __func__, version_count);
  98
  99         ds_versions = kzalloc(version_count * sizeof(struct nfs4_ff_ds_version),
 100                               gfp_flags);
 101         if (!ds_versions)
 102                 goto out_scratch;
 103
 104         for (i = 0; i < version_count; i++) {
 105                 /* 20 = version(4) + minor_version(4) + rsize(4) + wsize(4) +
 106                  * tightly_coupled(4) */
 107                 p = xdr_inline_decode(&stream, 20);
 108                 if (unlikely(!p))
 109                         goto out_err_drain_dsaddrs;
 110                 ds_versions[i].version = be32_to_cpup(p++);
 111                 ds_versions[i].minor_version = be32_to_cpup(p++);
 112                 ds_versions[i].rsize = nfs_block_size(be32_to_cpup(p++), NULL);
 113                 ds_versions[i].wsize = nfs_block_size(be32_to_cpup(p++), NULL);
 114                 ds_versions[i].tightly_coupled = be32_to_cpup(p);
 115
 116                 if (ds_versions[i].rsize > NFS_MAX_FILE_IO_SIZE)
 117                         ds_versions[i].rsize = NFS_MAX_FILE_IO_SIZE;
 118                 if (ds_versions[i].wsize > NFS_MAX_FILE_IO_SIZE)
 119                         ds_versions[i].wsize = NFS_MAX_FILE_IO_SIZE;
 120
 121                 if (ds_versions[i].version != 3 || ds_versions[i].minor_version != 0) {
 122                         dprintk("%s: [%d] unsupported ds version %d-%d\n", __func__,
 123                                 i, ds_versions[i].version,
 124                                 ds_versions[i].minor_version);
 125                         ret = -EPROTONOSUPPORT;
 126                         goto out_err_drain_dsaddrs;
 127                 }
 128
 129                 dprintk("%s: [%d] vers %u minor_ver %u rsize %u wsize %u coupled %d\n",
 130                         __func__, i, ds_versions[i].version,
 131                         ds_versions[i].minor_version,
 132                         ds_versions[i].rsize,
 133                         ds_versions[i].wsize,
 134                         ds_versions[i].tightly_coupled);
 135         }
 136
 137         new_ds->ds_versions = ds_versions;
 138         new_ds->ds_versions_cnt = version_count;
 139
 140         new_ds->ds = nfs4_pnfs_ds_add(&dsaddrs, gfp_flags);
 141         if (!new_ds->ds)
 142                 goto out_err_drain_dsaddrs;
 143
 144         /* If DS was already in cache, free ds addrs */
 145         while (!list_empty(&dsaddrs)) {
 146                 da = list_first_entry(&dsaddrs,
 147                                       struct nfs4_pnfs_ds_addr,
 148                                       da_node);
 149                 list_del_init(&da->da_node);
 150                 kfree(da->da_remotestr);
 151                 kfree(da);
 152         }
 153
 154         __free_page(scratch);
 155         return new_ds;
 156
 157 out_err_drain_dsaddrs:
 158         while (!list_empty(&dsaddrs)) {
 159                 da = list_first_entry(&dsaddrs, 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         kfree(ds_versions);
 167 out_scratch:
 168         __free_page(scratch);
 169 out_err:
 170         kfree(new_ds);
 171
 172         dprintk("%s ERROR: returning %d\n", __func__, ret);
 173         return NULL;
 174 }
 175
 176 static void ff_layout_mark_devid_invalid(struct pnfs_layout_segment *lseg,
 177                 struct nfs4_deviceid_node *devid)
 178 {
 179         nfs4_mark_deviceid_unavailable(devid);
 180         if (!ff_layout_has_available_ds(lseg))
 181                 pnfs_error_mark_layout_for_return(lseg->pls_layout->plh_inode,
 182                                 lseg);
 183 }
 184
 185 static bool ff_layout_mirror_valid(struct pnfs_layout_segment *lseg,
 186                 struct nfs4_ff_layout_mirror *mirror)
 187 {
 188         if (mirror == NULL || mirror->mirror_ds == NULL) {
 189                 pnfs_error_mark_layout_for_return(lseg->pls_layout->plh_inode,
 190                                         lseg);
 191                 return false;
 192         }
 193         if (mirror->mirror_ds->ds == NULL) {
 194                 struct nfs4_deviceid_node *devid;
 195                 devid = &mirror->mirror_ds->id_node;
 196                 ff_layout_mark_devid_invalid(lseg, devid);
 197                 return false;
 198         }
 199         return true;
 200 }
 201
 202 static u64
 203 end_offset(u64 start, u64 len)
 204 {
 205         u64 end;
 206
 207         end = start + len;
 208         return end >= start ? end : NFS4_MAX_UINT64;
 209 }
 210
 211 static void extend_ds_error(struct nfs4_ff_layout_ds_err *err,
 212                             u64 offset, u64 length)
 213 {
 214         u64 end;
 215
 216         end = max_t(u64, end_offset(err->offset, err->length),
 217                     end_offset(offset, length));
 218         err->offset = min_t(u64, err->offset, offset);
 219         err->length = end - err->offset;
 220 }
 221
 222 static bool ds_error_can_merge(struct nfs4_ff_layout_ds_err *err,  u64 offset,
 223                                u64 length, int status, enum nfs_opnum4 opnum,
 224                                nfs4_stateid *stateid,
 225                                struct nfs4_deviceid *deviceid)
 226 {
 227         return err->status == status && err->opnum == opnum &&
 228                nfs4_stateid_match(&err->stateid, stateid) &&
 229                !memcmp(&err->deviceid, deviceid, sizeof(*deviceid)) &&
 230                end_offset(err->offset, err->length) >= offset &&
 231                err->offset <= end_offset(offset, length);
 232 }
 233
 234 static bool merge_ds_error(struct nfs4_ff_layout_ds_err *old,
 235                            struct nfs4_ff_layout_ds_err *new)
 236 {
 237         if (!ds_error_can_merge(old, new->offset, new->length, new->status,
 238                                 new->opnum, &new->stateid, &new->deviceid))
 239                 return false;
 240
 241         extend_ds_error(old, new->offset, new->length);
 242         return true;
 243 }
 244
 245 static bool
 246 ff_layout_add_ds_error_locked(struct nfs4_flexfile_layout *flo,
 247                               struct nfs4_ff_layout_ds_err *dserr)
 248 {
 249         struct nfs4_ff_layout_ds_err *err;
 250
 251         list_for_each_entry(err, &flo->error_list, list) {
 252                 if (merge_ds_error(err, dserr)) {
 253                         return true;
 254                 }
 255         }
 256
 257         list_add(&dserr->list, &flo->error_list);
 258         return false;
 259 }
 260
 261 static bool
 262 ff_layout_update_ds_error(struct nfs4_flexfile_layout *flo, u64 offset,
 263                           u64 length, int status, enum nfs_opnum4 opnum,
 264                           nfs4_stateid *stateid, struct nfs4_deviceid *deviceid)
 265 {
 266         bool found = false;
 267         struct nfs4_ff_layout_ds_err *err;
 268
 269         list_for_each_entry(err, &flo->error_list, list) {
 270                 if (ds_error_can_merge(err, offset, length, status, opnum,
 271                                        stateid, deviceid)) {
 272                         found = true;
 273                         extend_ds_error(err, offset, length);
 274                         break;
 275                 }
 276         }
 277
 278         return found;
 279 }
 280
 281 int ff_layout_track_ds_error(struct nfs4_flexfile_layout *flo,
 282                              struct nfs4_ff_layout_mirror *mirror, u64 offset,
 283                              u64 length, int status, enum nfs_opnum4 opnum,
 284                              gfp_t gfp_flags)
 285 {
 286         struct nfs4_ff_layout_ds_err *dserr;
 287         bool needfree;
 288
 289         if (status == 0)
 290                 return 0;
 291
 292         if (mirror->mirror_ds == NULL)
 293                 return -EINVAL;
 294
 295         spin_lock(&flo->generic_hdr.plh_inode->i_lock);
 296         if (ff_layout_update_ds_error(flo, offset, length, status, opnum,
 297                                       &mirror->stateid,
 298                                       &mirror->mirror_ds->id_node.deviceid)) {
 299                 spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
 300                 return 0;
 301         }
 302         spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
 303         dserr = kmalloc(sizeof(*dserr), gfp_flags);
 304         if (!dserr)
 305                 return -ENOMEM;
 306
 307         INIT_LIST_HEAD(&dserr->list);
 308         dserr->offset = offset;
 309         dserr->length = length;
 310         dserr->status = status;
 311         dserr->opnum = opnum;
 312         nfs4_stateid_copy(&dserr->stateid, &mirror->stateid);
 313         memcpy(&dserr->deviceid, &mirror->mirror_ds->id_node.deviceid,
 314                NFS4_DEVICEID4_SIZE);
 315
 316         spin_lock(&flo->generic_hdr.plh_inode->i_lock);
 317         needfree = ff_layout_add_ds_error_locked(flo, dserr);
 318         spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
 319         if (needfree)
 320                 kfree(dserr);
 321
 322         return 0;
 323 }
 324
 325 /* currently we only support AUTH_NONE and AUTH_SYS */
 326 static rpc_authflavor_t
 327 nfs4_ff_layout_choose_authflavor(struct nfs4_ff_layout_mirror *mirror)
 328 {
 329         if (mirror->uid == (u32)-1)
 330                 return RPC_AUTH_NULL;
 331         return RPC_AUTH_UNIX;
 332 }
 333
 334 /* fetch cred for NFSv3 DS */
 335 static int ff_layout_update_mirror_cred(struct nfs4_ff_layout_mirror *mirror,
 336                                       struct nfs4_pnfs_ds *ds)
 337 {
 338         if (ds->ds_clp && !mirror->cred &&
 339             mirror->mirror_ds->ds_versions[0].version == 3) {
 340                 struct rpc_auth *auth = ds->ds_clp->cl_rpcclient->cl_auth;
 341                 struct rpc_cred *cred;
 342                 struct auth_cred acred = {
 343                         .uid = make_kuid(&init_user_ns, mirror->uid),
 344                         .gid = make_kgid(&init_user_ns, mirror->gid),
 345                 };
 346
 347                 /* AUTH_NULL ignores acred */
 348                 cred = auth->au_ops->lookup_cred(auth, &acred, 0);
 349                 if (IS_ERR(cred)) {
 350                         dprintk("%s: lookup_cred failed with %ld\n",
 351                                 __func__, PTR_ERR(cred));
 352                         return PTR_ERR(cred);
 353                 } else {
 354                         if (cmpxchg(&mirror->cred, NULL, cred))
 355                                 put_rpccred(cred);
 356                 }
 357         }
 358         return 0;
 359 }
 360
 361 struct nfs_fh *
 362 nfs4_ff_layout_select_ds_fh(struct pnfs_layout_segment *lseg, u32 mirror_idx)
 363 {
 364         struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, mirror_idx);
 365         struct nfs_fh *fh = NULL;
 366
 367         if (!ff_layout_mirror_valid(lseg, mirror)) {
 368                 pr_err_ratelimited("NFS: %s: No data server for mirror offset index %d\n",
 369                         __func__, mirror_idx);
 370                 goto out;
 371         }
 372
 373         /* FIXME: For now assume there is only 1 version available for the DS */
 374         fh = &mirror->fh_versions[0];
 375 out:
 376         return fh;
 377 }
 378
 379 /* Upon return, either ds is connected, or ds is NULL */
 380 struct nfs4_pnfs_ds *
 381 nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx,
 382                           bool fail_return)
 383 {
 384         struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);
 385         struct nfs4_pnfs_ds *ds = NULL;
 386         struct nfs4_deviceid_node *devid;
 387         struct inode *ino = lseg->pls_layout->plh_inode;
 388         struct nfs_server *s = NFS_SERVER(ino);
 389         unsigned int max_payload;
 390         rpc_authflavor_t flavor;
 391
 392         if (!ff_layout_mirror_valid(lseg, mirror)) {
 393                 pr_err_ratelimited("NFS: %s: No data server for offset index %d\n",
 394                         __func__, ds_idx);
 395                 goto out;
 396         }
 397
 398         devid = &mirror->mirror_ds->id_node;
 399         if (ff_layout_test_devid_unavailable(devid))
 400                 goto out;
 401
 402         ds = mirror->mirror_ds->ds;
 403         /* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */
 404         smp_rmb();
 405         if (ds->ds_clp)
 406                 goto out_update_creds;
 407
 408         flavor = nfs4_ff_layout_choose_authflavor(mirror);
 409
 410         /* FIXME: For now we assume the server sent only one version of NFS
 411          * to use for the DS.
 412          */
 413         nfs4_pnfs_ds_connect(s, ds, devid, dataserver_timeo,
 414                              dataserver_retrans,
 415                              mirror->mirror_ds->ds_versions[0].version,
 416                              mirror->mirror_ds->ds_versions[0].minor_version,
 417                              flavor);
 418
 419         /* connect success, check rsize/wsize limit */
 420         if (ds->ds_clp) {
 421                 max_payload =
 422                         nfs_block_size(rpc_max_payload(ds->ds_clp->cl_rpcclient),
 423                                        NULL);
 424                 if (mirror->mirror_ds->ds_versions[0].rsize > max_payload)
 425                         mirror->mirror_ds->ds_versions[0].rsize = max_payload;
 426                 if (mirror->mirror_ds->ds_versions[0].wsize > max_payload)
 427                         mirror->mirror_ds->ds_versions[0].wsize = max_payload;
 428         } else {
 429                 ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout),
 430                                          mirror, lseg->pls_range.offset,
 431                                          lseg->pls_range.length, NFS4ERR_NXIO,
 432                                          OP_ILLEGAL, GFP_NOIO);
 433                 if (fail_return) {
 434                         pnfs_error_mark_layout_for_return(ino, lseg);
 435                         if (ff_layout_has_available_ds(lseg))
 436                                 pnfs_set_retry_layoutget(lseg->pls_layout);
 437                         else
 438                                 pnfs_clear_retry_layoutget(lseg->pls_layout);
 439
 440                 } else {
 441                         if (ff_layout_has_available_ds(lseg))
 442                                 set_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE,
 443                                         &lseg->pls_layout->plh_flags);
 444                         else {
 445                                 pnfs_error_mark_layout_for_return(ino, lseg);
 446                                 pnfs_clear_retry_layoutget(lseg->pls_layout);
 447                         }
 448                 }
 449         }
 450 out_update_creds:
 451         if (ff_layout_update_mirror_cred(mirror, ds))
 452                 ds = NULL;
 453 out:
 454         return ds;
 455 }
 456
 457 struct rpc_cred *
 458 ff_layout_get_ds_cred(struct pnfs_layout_segment *lseg, u32 ds_idx,
 459                       struct rpc_cred *mdscred)
 460 {
 461         struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);
 462         struct rpc_cred *cred = ERR_PTR(-EINVAL);
 463
 464         if (!nfs4_ff_layout_prepare_ds(lseg, ds_idx, true))
 465                 goto out;
 466
 467         if (mirror && mirror->cred)
 468                 cred = mirror->cred;
 469         else
 470                 cred = mdscred;
 471 out:
 472         return cred;
 473 }
 474
 475 /**
 476 * Find or create a DS rpc client with th MDS server rpc client auth flavor
 477 * in the nfs_client cl_ds_clients list.
 478 */
 479 struct rpc_clnt *
 480 nfs4_ff_find_or_create_ds_client(struct pnfs_layout_segment *lseg, u32 ds_idx,
 481                                  struct nfs_client *ds_clp, struct inode *inode)
 482 {
 483         struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);
 484
 485         switch (mirror->mirror_ds->ds_versions[0].version) {
 486         case 3:
 487                 /* For NFSv3 DS, flavor is set when creating DS connections */
 488                 return ds_clp->cl_rpcclient;
 489         case 4:
 490                 return nfs4_find_or_create_ds_client(ds_clp, inode);
 491         default:
 492                 BUG();
 493         }
 494 }
 495
 496 static bool is_range_intersecting(u64 offset1, u64 length1,
 497                                   u64 offset2, u64 length2)
 498 {
 499         u64 end1 = end_offset(offset1, length1);
 500         u64 end2 = end_offset(offset2, length2);
 501
 502         return (end1 == NFS4_MAX_UINT64 || end1 > offset2) &&
 503                (end2 == NFS4_MAX_UINT64 || end2 > offset1);
 504 }
 505
 506 /* called with inode i_lock held */
 507 int ff_layout_encode_ds_ioerr(struct nfs4_flexfile_layout *flo,
 508                               struct xdr_stream *xdr, int *count,
 509                               const struct pnfs_layout_range *range)
 510 {
 511         struct nfs4_ff_layout_ds_err *err, *n;
 512         __be32 *p;
 513
 514         list_for_each_entry_safe(err, n, &flo->error_list, list) {
 515                 if (!is_range_intersecting(err->offset, err->length,
 516                                            range->offset, range->length))
 517                         continue;
 518                 /* offset(8) + length(8) + stateid(NFS4_STATEID_SIZE)
 519                  * + array length + deviceid(NFS4_DEVICEID4_SIZE)
 520                  * + status(4) + opnum(4)
 521                  */
 522                 p = xdr_reserve_space(xdr,
 523                                 28 + NFS4_STATEID_SIZE + NFS4_DEVICEID4_SIZE);
 524                 if (unlikely(!p))
 525                         return -ENOBUFS;
 526                 p = xdr_encode_hyper(p, err->offset);
 527                 p = xdr_encode_hyper(p, err->length);
 528                 p = xdr_encode_opaque_fixed(p, &err->stateid,
 529                                             NFS4_STATEID_SIZE);
 530                 /* Encode 1 error */
 531                 *p++ = cpu_to_be32(1);
 532                 p = xdr_encode_opaque_fixed(p, &err->deviceid,
 533                                             NFS4_DEVICEID4_SIZE);
 534                 *p++ = cpu_to_be32(err->status);
 535                 *p++ = cpu_to_be32(err->opnum);
 536                 *count += 1;
 537                 list_del(&err->list);
 538                 dprintk("%s: offset %llu length %llu status %d op %d count %d\n",
 539                         __func__, err->offset, err->length, err->status,
 540                         err->opnum, *count);
 541                 kfree(err);
 542         }
 543
 544         return 0;
 545 }
 546
 547 static bool ff_read_layout_has_available_ds(struct pnfs_layout_segment *lseg)
 548 {
 549         struct nfs4_ff_layout_mirror *mirror;
 550         struct nfs4_deviceid_node *devid;
 551         u32 idx;
 552
 553         for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
 554                 mirror = FF_LAYOUT_COMP(lseg, idx);
 555                 if (mirror && mirror->mirror_ds) {
 556                         devid = &mirror->mirror_ds->id_node;
 557                         if (!ff_layout_test_devid_unavailable(devid))
 558                                 return true;
 559                 }
 560         }
 561
 562         return false;
 563 }
 564
 565 static bool ff_rw_layout_has_available_ds(struct pnfs_layout_segment *lseg)
 566 {
 567         struct nfs4_ff_layout_mirror *mirror;
 568         struct nfs4_deviceid_node *devid;
 569         u32 idx;
 570
 571         for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
 572                 mirror = FF_LAYOUT_COMP(lseg, idx);
 573                 if (!mirror || !mirror->mirror_ds)
 574                         return false;
 575                 devid = &mirror->mirror_ds->id_node;
 576                 if (ff_layout_test_devid_unavailable(devid))
 577                         return false;
 578         }
 579
 580         return FF_LAYOUT_MIRROR_COUNT(lseg) != 0;
 581 }
 582
 583 bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg)
 584 {
 585         if (lseg->pls_range.iomode == IOMODE_READ)
 586                 return  ff_read_layout_has_available_ds(lseg);
 587         /* Note: RW layout needs all mirrors available */
 588         return ff_rw_layout_has_available_ds(lseg);
 589 }
 590
 591 module_param(dataserver_retrans, uint, 0644);
 592 MODULE_PARM_DESC(dataserver_retrans, "The  number of times the NFSv4.1 client "
 593                         "retries a request before it attempts further "
 594                         " recovery  action.");
 595 module_param(dataserver_timeo, uint, 0644);
 596 MODULE_PARM_DESC(dataserver_timeo, "The time (in tenths of a second) the "
 597                         "NFSv4.1  client  waits for a response from a "
 598                         " data server before it retries an NFS request.");