kernel/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_rcu(mirror_ds, id_node.rcu);
  34 }
  35
  36 /* Decode opaque device data and construct new_ds using it */
  37 struct nfs4_ff_layout_ds *
  38 nfs4_ff_alloc_deviceid_node(struct nfs_server *server, struct pnfs_device *pdev,
  39                             gfp_t gfp_flags)
  40 {
  41         struct xdr_stream stream;
  42         struct xdr_buf buf;
  43         struct page *scratch;
  44         struct list_head dsaddrs;
  45         struct nfs4_pnfs_ds_addr *da;
  46         struct nfs4_ff_layout_ds *new_ds = NULL;
  47         struct nfs4_ff_ds_version *ds_versions = NULL;
  48         u32 mp_count;
  49         u32 version_count;
  50         __be32 *p;
  51         int i, ret = -ENOMEM;
  52
  53         /* set up xdr stream */
  54         scratch = alloc_page(gfp_flags);
  55         if (!scratch)
  56                 goto out_err;
  57
  58         new_ds = kzalloc(sizeof(struct nfs4_ff_layout_ds), gfp_flags);
  59         if (!new_ds)
  60                 goto out_scratch;
  61
  62         nfs4_init_deviceid_node(&new_ds->id_node,
  63                                 server,
  64                                 &pdev->dev_id);
  65         INIT_LIST_HEAD(&dsaddrs);
  66
  67         xdr_init_decode_pages(&stream, &buf, pdev->pages, pdev->pglen);
  68         xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE);
  69
  70         /* multipath count */
  71         p = xdr_inline_decode(&stream, 4);
  72         if (unlikely(!p))
  73                 goto out_err_drain_dsaddrs;
  74         mp_count = be32_to_cpup(p);
  75         dprintk("%s: multipath ds count %d\n", __func__, mp_count);
  76
  77         for (i = 0; i < mp_count; i++) {
  78                 /* multipath ds */
  79                 da = nfs4_decode_mp_ds_addr(server->nfs_client->cl_net,
  80                                             &stream, gfp_flags);
  81                 if (da)
  82                         list_add_tail(&da->da_node, &dsaddrs);
  83         }
  84         if (list_empty(&dsaddrs)) {
  85                 dprintk("%s: no suitable DS addresses found\n",
  86                         __func__);
  87                 ret = -ENOMEDIUM;
  88                 goto out_err_drain_dsaddrs;
  89         }
  90
  91         /* version count */
  92         p = xdr_inline_decode(&stream, 4);
  93         if (unlikely(!p))
  94                 goto out_err_drain_dsaddrs;
  95         version_count = be32_to_cpup(p);
  96         dprintk("%s: version count %d\n", __func__, version_count);
  97
  98         ds_versions = kzalloc(version_count * sizeof(struct nfs4_ff_ds_version),
  99                               gfp_flags);
 100         if (!ds_versions)
 101                 goto out_scratch;
 102
 103         for (i = 0; i < version_count; i++) {
 104                 /* 20 = version(4) + minor_version(4) + rsize(4) + wsize(4) +
 105                  * tightly_coupled(4) */
 106                 p = xdr_inline_decode(&stream, 20);
 107                 if (unlikely(!p))
 108                         goto out_err_drain_dsaddrs;
 109                 ds_versions[i].version = be32_to_cpup(p++);
 110                 ds_versions[i].minor_version = be32_to_cpup(p++);
 111                 ds_versions[i].rsize = nfs_block_size(be32_to_cpup(p++), NULL);
 112                 ds_versions[i].wsize = nfs_block_size(be32_to_cpup(p++), NULL);
 113                 ds_versions[i].tightly_coupled = be32_to_cpup(p);
 114
 115                 if (ds_versions[i].rsize > NFS_MAX_FILE_IO_SIZE)
 116                         ds_versions[i].rsize = NFS_MAX_FILE_IO_SIZE;
 117                 if (ds_versions[i].wsize > NFS_MAX_FILE_IO_SIZE)
 118                         ds_versions[i].wsize = NFS_MAX_FILE_IO_SIZE;
 119
 120                 if (ds_versions[i].version != 3 || ds_versions[i].minor_version != 0) {
 121                         dprintk("%s: [%d] unsupported ds version %d-%d\n", __func__,
 122                                 i, ds_versions[i].version,
 123                                 ds_versions[i].minor_version);
 124                         ret = -EPROTONOSUPPORT;
 125                         goto out_err_drain_dsaddrs;
 126                 }
 127
 128                 dprintk("%s: [%d] vers %u minor_ver %u rsize %u wsize %u coupled %d\n",
 129                         __func__, i, ds_versions[i].version,
 130                         ds_versions[i].minor_version,
 131                         ds_versions[i].rsize,
 132                         ds_versions[i].wsize,
 133                         ds_versions[i].tightly_coupled);
 134         }
 135
 136         new_ds->ds_versions = ds_versions;
 137         new_ds->ds_versions_cnt = version_count;
 138
 139         new_ds->ds = nfs4_pnfs_ds_add(&dsaddrs, gfp_flags);
 140         if (!new_ds->ds)
 141                 goto out_err_drain_dsaddrs;
 142
 143         /* If DS was already in cache, free ds addrs */
 144         while (!list_empty(&dsaddrs)) {
 145                 da = list_first_entry(&dsaddrs,
 146                                       struct nfs4_pnfs_ds_addr,
 147                                       da_node);
 148                 list_del_init(&da->da_node);
 149                 kfree(da->da_remotestr);
 150                 kfree(da);
 151         }
 152
 153         __free_page(scratch);
 154         return new_ds;
 155
 156 out_err_drain_dsaddrs:
 157         while (!list_empty(&dsaddrs)) {
 158                 da = list_first_entry(&dsaddrs, struct nfs4_pnfs_ds_addr,
 159                                       da_node);
 160                 list_del_init(&da->da_node);
 161                 kfree(da->da_remotestr);
 162                 kfree(da);
 163         }
 164
 165         kfree(ds_versions);
 166 out_scratch:
 167         __free_page(scratch);
 168 out_err:
 169         kfree(new_ds);
 170
 171         dprintk("%s ERROR: returning %d\n", __func__, ret);
 172         return NULL;
 173 }
 174
 175 static void ff_layout_mark_devid_invalid(struct pnfs_layout_segment *lseg,
 176                 struct nfs4_deviceid_node *devid)
 177 {
 178         nfs4_mark_deviceid_unavailable(devid);
 179         if (!ff_layout_has_available_ds(lseg))
 180                 pnfs_error_mark_layout_for_return(lseg->pls_layout->plh_inode,
 181                                 lseg);
 182 }
 183
 184 static bool ff_layout_mirror_valid(struct pnfs_layout_segment *lseg,
 185                 struct nfs4_ff_layout_mirror *mirror)
 186 {
 187         if (mirror == NULL || mirror->mirror_ds == NULL) {
 188                 pnfs_error_mark_layout_for_return(lseg->pls_layout->plh_inode,
 189                                         lseg);
 190                 return false;
 191         }
 192         if (mirror->mirror_ds->ds == NULL) {
 193                 struct nfs4_deviceid_node *devid;
 194                 devid = &mirror->mirror_ds->id_node;
 195                 ff_layout_mark_devid_invalid(lseg, devid);
 196                 return false;
 197         }
 198         return true;
 199 }
 200
 201 static u64
 202 end_offset(u64 start, u64 len)
 203 {
 204         u64 end;
 205
 206         end = start + len;
 207         return end >= start ? end : NFS4_MAX_UINT64;
 208 }
 209
 210 static void extend_ds_error(struct nfs4_ff_layout_ds_err *err,
 211                             u64 offset, u64 length)
 212 {
 213         u64 end;
 214
 215         end = max_t(u64, end_offset(err->offset, err->length),
 216                     end_offset(offset, length));
 217         err->offset = min_t(u64, err->offset, offset);
 218         err->length = end - err->offset;
 219 }
 220
 221 static bool ds_error_can_merge(struct nfs4_ff_layout_ds_err *err,  u64 offset,
 222                                u64 length, int status, enum nfs_opnum4 opnum,
 223                                nfs4_stateid *stateid,
 224                                struct nfs4_deviceid *deviceid)
 225 {
 226         return err->status == status && err->opnum == opnum &&
 227                nfs4_stateid_match(&err->stateid, stateid) &&
 228                !memcmp(&err->deviceid, deviceid, sizeof(*deviceid)) &&
 229                end_offset(err->offset, err->length) >= offset &&
 230                err->offset <= end_offset(offset, length);
 231 }
 232
 233 static bool merge_ds_error(struct nfs4_ff_layout_ds_err *old,
 234                            struct nfs4_ff_layout_ds_err *new)
 235 {
 236         if (!ds_error_can_merge(old, new->offset, new->length, new->status,
 237                                 new->opnum, &new->stateid, &new->deviceid))
 238                 return false;
 239
 240         extend_ds_error(old, new->offset, new->length);
 241         return true;
 242 }
 243
 244 static bool
 245 ff_layout_add_ds_error_locked(struct nfs4_flexfile_layout *flo,
 246                               struct nfs4_ff_layout_ds_err *dserr)
 247 {
 248         struct nfs4_ff_layout_ds_err *err;
 249
 250         list_for_each_entry(err, &flo->error_list, list) {
 251                 if (merge_ds_error(err, dserr)) {
 252                         return true;
 253                 }
 254         }
 255
 256         list_add(&dserr->list, &flo->error_list);
 257         return false;
 258 }
 259
 260 static bool
 261 ff_layout_update_ds_error(struct nfs4_flexfile_layout *flo, u64 offset,
 262                           u64 length, int status, enum nfs_opnum4 opnum,
 263                           nfs4_stateid *stateid, struct nfs4_deviceid *deviceid)
 264 {
 265         bool found = false;
 266         struct nfs4_ff_layout_ds_err *err;
 267
 268         list_for_each_entry(err, &flo->error_list, list) {
 269                 if (ds_error_can_merge(err, offset, length, status, opnum,
 270                                        stateid, deviceid)) {
 271                         found = true;
 272                         extend_ds_error(err, offset, length);
 273                         break;
 274                 }
 275         }
 276
 277         return found;
 278 }
 279
 280 int ff_layout_track_ds_error(struct nfs4_flexfile_layout *flo,
 281                              struct nfs4_ff_layout_mirror *mirror, u64 offset,
 282                              u64 length, int status, enum nfs_opnum4 opnum,
 283                              gfp_t gfp_flags)
 284 {
 285         struct nfs4_ff_layout_ds_err *dserr;
 286         bool needfree;
 287
 288         if (status == 0)
 289                 return 0;
 290
 291         if (mirror->mirror_ds == NULL)
 292                 return -EINVAL;
 293
 294         spin_lock(&flo->generic_hdr.plh_inode->i_lock);
 295         if (ff_layout_update_ds_error(flo, offset, length, status, opnum,
 296                                       &mirror->stateid,
 297                                       &mirror->mirror_ds->id_node.deviceid)) {
 298                 spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
 299                 return 0;
 300         }
 301         spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
 302         dserr = kmalloc(sizeof(*dserr), gfp_flags);
 303         if (!dserr)
 304                 return -ENOMEM;
 305
 306         INIT_LIST_HEAD(&dserr->list);
 307         dserr->offset = offset;
 308         dserr->length = length;
 309         dserr->status = status;
 310         dserr->opnum = opnum;
 311         nfs4_stateid_copy(&dserr->stateid, &mirror->stateid);
 312         memcpy(&dserr->deviceid, &mirror->mirror_ds->id_node.deviceid,
 313                NFS4_DEVICEID4_SIZE);
 314
 315         spin_lock(&flo->generic_hdr.plh_inode->i_lock);
 316         needfree = ff_layout_add_ds_error_locked(flo, dserr);
 317         spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
 318         if (needfree)
 319                 kfree(dserr);
 320
 321         return 0;
 322 }
 323
 324 /* currently we only support AUTH_NONE and AUTH_SYS */
 325 static rpc_authflavor_t
 326 nfs4_ff_layout_choose_authflavor(struct nfs4_ff_layout_mirror *mirror)
 327 {
 328         if (mirror->uid == (u32)-1)
 329                 return RPC_AUTH_NULL;
 330         return RPC_AUTH_UNIX;
 331 }
 332
 333 /* fetch cred for NFSv3 DS */
 334 static int ff_layout_update_mirror_cred(struct nfs4_ff_layout_mirror *mirror,
 335                                       struct nfs4_pnfs_ds *ds)
 336 {
 337         if (ds->ds_clp && !mirror->cred &&
 338             mirror->mirror_ds->ds_versions[0].version == 3) {
 339                 struct rpc_auth *auth = ds->ds_clp->cl_rpcclient->cl_auth;
 340                 struct rpc_cred *cred;
 341                 struct auth_cred acred = {
 342                         .uid = make_kuid(&init_user_ns, mirror->uid),
 343                         .gid = make_kgid(&init_user_ns, mirror->gid),
 344                 };
 345
 346                 /* AUTH_NULL ignores acred */
 347                 cred = auth->au_ops->lookup_cred(auth, &acred, 0);
 348                 if (IS_ERR(cred)) {
 349                         dprintk("%s: lookup_cred failed with %ld\n",
 350                                 __func__, PTR_ERR(cred));
 351                         return PTR_ERR(cred);
 352                 } else {
 353                         if (cmpxchg(&mirror->cred, NULL, cred))
 354                                 put_rpccred(cred);
 355                 }
 356         }
 357         return 0;
 358 }
 359
 360 struct nfs_fh *
 361 nfs4_ff_layout_select_ds_fh(struct pnfs_layout_segment *lseg, u32 mirror_idx)
 362 {
 363         struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, mirror_idx);
 364         struct nfs_fh *fh = NULL;
 365
 366         if (!ff_layout_mirror_valid(lseg, mirror)) {
 367                 pr_err_ratelimited("NFS: %s: No data server for mirror offset index %d\n",
 368                         __func__, mirror_idx);
 369                 goto out;
 370         }
 371
 372         /* FIXME: For now assume there is only 1 version available for the DS */
 373         fh = &mirror->fh_versions[0];
 374 out:
 375         return fh;
 376 }
 377
 378 /* Upon return, either ds is connected, or ds is NULL */
 379 struct nfs4_pnfs_ds *
 380 nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx,
 381                           bool fail_return)
 382 {
 383         struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);
 384         struct nfs4_pnfs_ds *ds = NULL;
 385         struct nfs4_deviceid_node *devid;
 386         struct inode *ino = lseg->pls_layout->plh_inode;
 387         struct nfs_server *s = NFS_SERVER(ino);
 388         unsigned int max_payload;
 389         rpc_authflavor_t flavor;
 390
 391         if (!ff_layout_mirror_valid(lseg, mirror)) {
 392                 pr_err_ratelimited("NFS: %s: No data server for offset index %d\n",
 393                         __func__, ds_idx);
 394                 goto out;
 395         }
 396
 397         devid = &mirror->mirror_ds->id_node;
 398         if (ff_layout_test_devid_unavailable(devid))
 399                 goto out;
 400
 401         ds = mirror->mirror_ds->ds;
 402         /* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */
 403         smp_rmb();
 404         if (ds->ds_clp)
 405                 goto out_update_creds;
 406
 407         flavor = nfs4_ff_layout_choose_authflavor(mirror);
 408
 409         /* FIXME: For now we assume the server sent only one version of NFS
 410          * to use for the DS.
 411          */
 412         nfs4_pnfs_ds_connect(s, ds, devid, dataserver_timeo,
 413                              dataserver_retrans,
 414                              mirror->mirror_ds->ds_versions[0].version,
 415                              mirror->mirror_ds->ds_versions[0].minor_version,
 416                              flavor);
 417
 418         /* connect success, check rsize/wsize limit */
 419         if (ds->ds_clp) {
 420                 max_payload =
 421                         nfs_block_size(rpc_max_payload(ds->ds_clp->cl_rpcclient),
 422                                        NULL);
 423                 if (mirror->mirror_ds->ds_versions[0].rsize > max_payload)
 424                         mirror->mirror_ds->ds_versions[0].rsize = max_payload;
 425                 if (mirror->mirror_ds->ds_versions[0].wsize > max_payload)
 426                         mirror->mirror_ds->ds_versions[0].wsize = max_payload;
 427         } else {
 428                 ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout),
 429                                          mirror, lseg->pls_range.offset,
 430                                          lseg->pls_range.length, NFS4ERR_NXIO,
 431                                          OP_ILLEGAL, GFP_NOIO);
 432                 if (fail_return) {
 433                         pnfs_error_mark_layout_for_return(ino, lseg);
 434                         if (ff_layout_has_available_ds(lseg))
 435                                 pnfs_set_retry_layoutget(lseg->pls_layout);
 436                         else
 437                                 pnfs_clear_retry_layoutget(lseg->pls_layout);
 438
 439                 } else {
 440                         if (ff_layout_has_available_ds(lseg))
 441                                 set_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE,
 442                                         &lseg->pls_layout->plh_flags);
 443                         else {
 444                                 pnfs_error_mark_layout_for_return(ino, lseg);
 445                                 pnfs_clear_retry_layoutget(lseg->pls_layout);
 446                         }
 447                 }
 448         }
 449 out_update_creds:
 450         if (ff_layout_update_mirror_cred(mirror, ds))
 451                 ds = NULL;
 452 out:
 453         return ds;
 454 }
 455
 456 struct rpc_cred *
 457 ff_layout_get_ds_cred(struct pnfs_layout_segment *lseg, u32 ds_idx,
 458                       struct rpc_cred *mdscred)
 459 {
 460         struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);
 461         struct rpc_cred *cred = ERR_PTR(-EINVAL);
 462
 463         if (!nfs4_ff_layout_prepare_ds(lseg, ds_idx, true))
 464                 goto out;
 465
 466         if (mirror && mirror->cred)
 467                 cred = mirror->cred;
 468         else
 469                 cred = mdscred;
 470 out:
 471         return cred;
 472 }
 473
 474 /**
 475 * Find or create a DS rpc client with th MDS server rpc client auth flavor
 476 * in the nfs_client cl_ds_clients list.
 477 */
 478 struct rpc_clnt *
 479 nfs4_ff_find_or_create_ds_client(struct pnfs_layout_segment *lseg, u32 ds_idx,
 480                                  struct nfs_client *ds_clp, struct inode *inode)
 481 {
 482         struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);
 483
 484         switch (mirror->mirror_ds->ds_versions[0].version) {
 485         case 3:
 486                 /* For NFSv3 DS, flavor is set when creating DS connections */
 487                 return ds_clp->cl_rpcclient;
 488         case 4:
 489                 return nfs4_find_or_create_ds_client(ds_clp, inode);
 490         default:
 491                 BUG();
 492         }
 493 }
 494
 495 static bool is_range_intersecting(u64 offset1, u64 length1,
 496                                   u64 offset2, u64 length2)
 497 {
 498         u64 end1 = end_offset(offset1, length1);
 499         u64 end2 = end_offset(offset2, length2);
 500
 501         return (end1 == NFS4_MAX_UINT64 || end1 > offset2) &&
 502                (end2 == NFS4_MAX_UINT64 || end2 > offset1);
 503 }
 504
 505 /* called with inode i_lock held */
 506 int ff_layout_encode_ds_ioerr(struct nfs4_flexfile_layout *flo,
 507                               struct xdr_stream *xdr, int *count,
 508                               const struct pnfs_layout_range *range)
 509 {
 510         struct nfs4_ff_layout_ds_err *err, *n;
 511         __be32 *p;
 512
 513         list_for_each_entry_safe(err, n, &flo->error_list, list) {
 514                 if (!is_range_intersecting(err->offset, err->length,
 515                                            range->offset, range->length))
 516                         continue;
 517                 /* offset(8) + length(8) + stateid(NFS4_STATEID_SIZE)
 518                  * + array length + deviceid(NFS4_DEVICEID4_SIZE)
 519                  * + status(4) + opnum(4)
 520                  */
 521                 p = xdr_reserve_space(xdr,
 522                                 28 + NFS4_STATEID_SIZE + NFS4_DEVICEID4_SIZE);
 523                 if (unlikely(!p))
 524                         return -ENOBUFS;
 525                 p = xdr_encode_hyper(p, err->offset);
 526                 p = xdr_encode_hyper(p, err->length);
 527                 p = xdr_encode_opaque_fixed(p, &err->stateid,
 528                                             NFS4_STATEID_SIZE);
 529                 /* Encode 1 error */
 530                 *p++ = cpu_to_be32(1);
 531                 p = xdr_encode_opaque_fixed(p, &err->deviceid,
 532                                             NFS4_DEVICEID4_SIZE);
 533                 *p++ = cpu_to_be32(err->status);
 534                 *p++ = cpu_to_be32(err->opnum);
 535                 *count += 1;
 536                 list_del(&err->list);
 537                 dprintk("%s: offset %llu length %llu status %d op %d count %d\n",
 538                         __func__, err->offset, err->length, err->status,
 539                         err->opnum, *count);
 540                 kfree(err);
 541         }
 542
 543         return 0;
 544 }
 545
 546 static bool ff_read_layout_has_available_ds(struct pnfs_layout_segment *lseg)
 547 {
 548         struct nfs4_ff_layout_mirror *mirror;
 549         struct nfs4_deviceid_node *devid;
 550         u32 idx;
 551
 552         for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
 553                 mirror = FF_LAYOUT_COMP(lseg, idx);
 554                 if (mirror && mirror->mirror_ds) {
 555                         devid = &mirror->mirror_ds->id_node;
 556                         if (!ff_layout_test_devid_unavailable(devid))
 557                                 return true;
 558                 }
 559         }
 560
 561         return false;
 562 }
 563
 564 static bool ff_rw_layout_has_available_ds(struct pnfs_layout_segment *lseg)
 565 {
 566         struct nfs4_ff_layout_mirror *mirror;
 567         struct nfs4_deviceid_node *devid;
 568         u32 idx;
 569
 570         for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
 571                 mirror = FF_LAYOUT_COMP(lseg, idx);
 572                 if (!mirror || !mirror->mirror_ds)
 573                         return false;
 574                 devid = &mirror->mirror_ds->id_node;
 575                 if (ff_layout_test_devid_unavailable(devid))
 576                         return false;
 577         }
 578
 579         return FF_LAYOUT_MIRROR_COUNT(lseg) != 0;
 580 }
 581
 582 bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg)
 583 {
 584         if (lseg->pls_range.iomode == IOMODE_READ)
 585                 return  ff_read_layout_has_available_ds(lseg);
 586         /* Note: RW layout needs all mirrors available */
 587         return ff_rw_layout_has_available_ds(lseg);
 588 }
 589
 590 module_param(dataserver_retrans, uint, 0644);
 591 MODULE_PARM_DESC(dataserver_retrans, "The  number of times the NFSv4.1 client "
 592                         "retries a request before it attempts further "
 593                         " recovery  action.");
 594 module_param(dataserver_timeo, uint, 0644);
 595 MODULE_PARM_DESC(dataserver_timeo, "The time (in tenths of a second) the "
 596                         "NFSv4.1  client  waits for a response from a "
 597                         " data server before it retries an NFS request.");