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 = NFS_DEF_TCP_RETRANS;
  21 static unsigned int dataserver_retrans;
  22
  23 static bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg);
  24
  25 void nfs4_ff_layout_put_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
  26 {
  27         if (!IS_ERR_OR_NULL(mirror_ds))
  28                 nfs4_put_deviceid_node(&mirror_ds->id_node);
  29 }
  30
  31 void nfs4_ff_layout_free_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
  32 {
  33         nfs4_print_deviceid(&mirror_ds->id_node.deviceid);
  34         nfs4_pnfs_ds_put(mirror_ds->ds);
  35         kfree_rcu(mirror_ds, id_node.rcu);
  36 }
  37
  38 /* Decode opaque device data and construct new_ds using it */
  39 struct nfs4_ff_layout_ds *
  40 nfs4_ff_alloc_deviceid_node(struct nfs_server *server, struct pnfs_device *pdev,
  41                             gfp_t gfp_flags)
  42 {
  43         struct xdr_stream stream;
  44         struct xdr_buf buf;
  45         struct page *scratch;
  46         struct list_head dsaddrs;
  47         struct nfs4_pnfs_ds_addr *da;
  48         struct nfs4_ff_layout_ds *new_ds = NULL;
  49         struct nfs4_ff_ds_version *ds_versions = NULL;
  50         u32 mp_count;
  51         u32 version_count;
  52         __be32 *p;
  53         int i, ret = -ENOMEM;
  54
  55         /* set up xdr stream */
  56         scratch = alloc_page(gfp_flags);
  57         if (!scratch)
  58                 goto out_err;
  59
  60         new_ds = kzalloc(sizeof(struct nfs4_ff_layout_ds), gfp_flags);
  61         if (!new_ds)
  62                 goto out_scratch;
  63
  64         nfs4_init_deviceid_node(&new_ds->id_node,
  65                                 server,
  66                                 &pdev->dev_id);
  67         INIT_LIST_HEAD(&dsaddrs);
  68
  69         xdr_init_decode_pages(&stream, &buf, pdev->pages, pdev->pglen);
  70         xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE);
  71
  72         /* multipath count */
  73         p = xdr_inline_decode(&stream, 4);
  74         if (unlikely(!p))
  75                 goto out_err_drain_dsaddrs;
  76         mp_count = be32_to_cpup(p);
  77         dprintk("%s: multipath ds count %d\n", __func__, mp_count);
  78
  79         for (i = 0; i < mp_count; i++) {
  80                 /* multipath ds */
  81                 da = nfs4_decode_mp_ds_addr(server->nfs_client->cl_net,
  82                                             &stream, gfp_flags);
  83                 if (da)
  84                         list_add_tail(&da->da_node, &dsaddrs);
  85         }
  86         if (list_empty(&dsaddrs)) {
  87                 dprintk("%s: no suitable DS addresses found\n",
  88                         __func__);
  89                 ret = -ENOMEDIUM;
  90                 goto out_err_drain_dsaddrs;
  91         }
  92
  93         /* version count */
  94         p = xdr_inline_decode(&stream, 4);
  95         if (unlikely(!p))
  96                 goto out_err_drain_dsaddrs;
  97         version_count = be32_to_cpup(p);
  98         dprintk("%s: version count %d\n", __func__, version_count);
  99
 100         ds_versions = kzalloc(version_count * sizeof(struct nfs4_ff_ds_version),
 101                               gfp_flags);
 102         if (!ds_versions)
 103                 goto out_scratch;
 104
 105         for (i = 0; i < version_count; i++) {
 106                 /* 20 = version(4) + minor_version(4) + rsize(4) + wsize(4) +
 107                  * tightly_coupled(4) */
 108                 p = xdr_inline_decode(&stream, 20);
 109                 if (unlikely(!p))
 110                         goto out_err_drain_dsaddrs;
 111                 ds_versions[i].version = be32_to_cpup(p++);
 112                 ds_versions[i].minor_version = be32_to_cpup(p++);
 113                 ds_versions[i].rsize = nfs_block_size(be32_to_cpup(p++), NULL);
 114                 ds_versions[i].wsize = nfs_block_size(be32_to_cpup(p++), NULL);
 115                 ds_versions[i].tightly_coupled = be32_to_cpup(p);
 116
 117                 if (ds_versions[i].rsize > NFS_MAX_FILE_IO_SIZE)
 118                         ds_versions[i].rsize = NFS_MAX_FILE_IO_SIZE;
 119                 if (ds_versions[i].wsize > NFS_MAX_FILE_IO_SIZE)
 120                         ds_versions[i].wsize = NFS_MAX_FILE_IO_SIZE;
 121
 122                 if (ds_versions[i].version != 3 || ds_versions[i].minor_version != 0) {
 123                         dprintk("%s: [%d] unsupported ds version %d-%d\n", __func__,
 124                                 i, ds_versions[i].version,
 125                                 ds_versions[i].minor_version);
 126                         ret = -EPROTONOSUPPORT;
 127                         goto out_err_drain_dsaddrs;
 128                 }
 129
 130                 dprintk("%s: [%d] vers %u minor_ver %u rsize %u wsize %u coupled %d\n",
 131                         __func__, i, ds_versions[i].version,
 132                         ds_versions[i].minor_version,
 133                         ds_versions[i].rsize,
 134                         ds_versions[i].wsize,
 135                         ds_versions[i].tightly_coupled);
 136         }
 137
 138         new_ds->ds_versions = ds_versions;
 139         new_ds->ds_versions_cnt = version_count;
 140
 141         new_ds->ds = nfs4_pnfs_ds_add(&dsaddrs, gfp_flags);
 142         if (!new_ds->ds)
 143                 goto out_err_drain_dsaddrs;
 144
 145         /* If DS was already in cache, free ds addrs */
 146         while (!list_empty(&dsaddrs)) {
 147                 da = list_first_entry(&dsaddrs,
 148                                       struct nfs4_pnfs_ds_addr,
 149                                       da_node);
 150                 list_del_init(&da->da_node);
 151                 kfree(da->da_remotestr);
 152                 kfree(da);
 153         }
 154
 155         __free_page(scratch);
 156         return new_ds;
 157
 158 out_err_drain_dsaddrs:
 159         while (!list_empty(&dsaddrs)) {
 160                 da = list_first_entry(&dsaddrs, struct nfs4_pnfs_ds_addr,
 161                                       da_node);
 162                 list_del_init(&da->da_node);
 163                 kfree(da->da_remotestr);
 164                 kfree(da);
 165         }
 166
 167         kfree(ds_versions);
 168 out_scratch:
 169         __free_page(scratch);
 170 out_err:
 171         kfree(new_ds);
 172
 173         dprintk("%s ERROR: returning %d\n", __func__, ret);
 174         return NULL;
 175 }
 176
 177 static void ff_layout_mark_devid_invalid(struct pnfs_layout_segment *lseg,
 178                 struct nfs4_deviceid_node *devid)
 179 {
 180         nfs4_delete_deviceid(devid->ld, devid->nfs_client, &devid->deviceid);
 181         if (!ff_layout_has_available_ds(lseg))
 182                 pnfs_error_mark_layout_for_return(lseg->pls_layout->plh_inode,
 183                                 lseg);
 184 }
 185
 186 static bool ff_layout_mirror_valid(struct pnfs_layout_segment *lseg,
 187                                    struct nfs4_ff_layout_mirror *mirror,
 188                                    bool create)
 189 {
 190         if (mirror == NULL || IS_ERR(mirror->mirror_ds))
 191                 goto outerr;
 192         if (mirror->mirror_ds == NULL) {
 193                 if (create) {
 194                         struct nfs4_deviceid_node *node;
 195                         struct pnfs_layout_hdr *lh = lseg->pls_layout;
 196                         struct nfs4_ff_layout_ds *mirror_ds = ERR_PTR(-ENODEV);
 197
 198                         node = nfs4_find_get_deviceid(NFS_SERVER(lh->plh_inode),
 199                                         &mirror->devid, lh->plh_lc_cred,
 200                                         GFP_KERNEL);
 201                         if (node)
 202                                 mirror_ds = FF_LAYOUT_MIRROR_DS(node);
 203
 204                         /* check for race with another call to this function */
 205                         if (cmpxchg(&mirror->mirror_ds, NULL, mirror_ds) &&
 206                             mirror_ds != ERR_PTR(-ENODEV))
 207                                 nfs4_put_deviceid_node(node);
 208                 } else
 209                         goto outerr;
 210         }
 211         if (mirror->mirror_ds->ds == NULL) {
 212                 struct nfs4_deviceid_node *devid;
 213                 devid = &mirror->mirror_ds->id_node;
 214                 ff_layout_mark_devid_invalid(lseg, devid);
 215                 return false;
 216         }
 217         return true;
 218 outerr:
 219         pnfs_error_mark_layout_for_return(lseg->pls_layout->plh_inode, lseg);
 220         return false;
 221 }
 222
 223 static void extend_ds_error(struct nfs4_ff_layout_ds_err *err,
 224                             u64 offset, u64 length)
 225 {
 226         u64 end;
 227
 228         end = max_t(u64, pnfs_end_offset(err->offset, err->length),
 229                     pnfs_end_offset(offset, length));
 230         err->offset = min_t(u64, err->offset, offset);
 231         err->length = end - err->offset;
 232 }
 233
 234 static int
 235 ff_ds_error_match(const struct nfs4_ff_layout_ds_err *e1,
 236                 const struct nfs4_ff_layout_ds_err *e2)
 237 {
 238         int ret;
 239
 240         if (e1->opnum != e2->opnum)
 241                 return e1->opnum < e2->opnum ? -1 : 1;
 242         if (e1->status != e2->status)
 243                 return e1->status < e2->status ? -1 : 1;
 244         ret = memcmp(e1->stateid.data, e2->stateid.data,
 245                         sizeof(e1->stateid.data));
 246         if (ret != 0)
 247                 return ret;
 248         ret = memcmp(&e1->deviceid, &e2->deviceid, sizeof(e1->deviceid));
 249         if (ret != 0)
 250                 return ret;
 251         if (pnfs_end_offset(e1->offset, e1->length) < e2->offset)
 252                 return -1;
 253         if (e1->offset > pnfs_end_offset(e2->offset, e2->length))
 254                 return 1;
 255         /* If ranges overlap or are contiguous, they are the same */
 256         return 0;
 257 }
 258
 259 static void
 260 ff_layout_add_ds_error_locked(struct nfs4_flexfile_layout *flo,
 261                               struct nfs4_ff_layout_ds_err *dserr)
 262 {
 263         struct nfs4_ff_layout_ds_err *err, *tmp;
 264         struct list_head *head = &flo->error_list;
 265         int match;
 266
 267         /* Do insertion sort w/ merges */
 268         list_for_each_entry_safe(err, tmp, &flo->error_list, list) {
 269                 match = ff_ds_error_match(err, dserr);
 270                 if (match < 0)
 271                         continue;
 272                 if (match > 0) {
 273                         /* Add entry "dserr" _before_ entry "err" */
 274                         head = &err->list;
 275                         break;
 276                 }
 277                 /* Entries match, so merge "err" into "dserr" */
 278                 extend_ds_error(dserr, err->offset, err->length);
 279                 list_replace(&err->list, &dserr->list);
 280                 kfree(err);
 281                 return;
 282         }
 283
 284         list_add_tail(&dserr->list, head);
 285 }
 286
 287 int ff_layout_track_ds_error(struct nfs4_flexfile_layout *flo,
 288                              struct nfs4_ff_layout_mirror *mirror, u64 offset,
 289                              u64 length, int status, enum nfs_opnum4 opnum,
 290                              gfp_t gfp_flags)
 291 {
 292         struct nfs4_ff_layout_ds_err *dserr;
 293
 294         if (status == 0)
 295                 return 0;
 296
 297         if (mirror->mirror_ds == NULL)
 298                 return -EINVAL;
 299
 300         dserr = kmalloc(sizeof(*dserr), gfp_flags);
 301         if (!dserr)
 302                 return -ENOMEM;
 303
 304         INIT_LIST_HEAD(&dserr->list);
 305         dserr->offset = offset;
 306         dserr->length = length;
 307         dserr->status = status;
 308         dserr->opnum = opnum;
 309         nfs4_stateid_copy(&dserr->stateid, &mirror->stateid);
 310         memcpy(&dserr->deviceid, &mirror->mirror_ds->id_node.deviceid,
 311                NFS4_DEVICEID4_SIZE);
 312
 313         spin_lock(&flo->generic_hdr.plh_inode->i_lock);
 314         ff_layout_add_ds_error_locked(flo, dserr);
 315         spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
 316
 317         return 0;
 318 }
 319
 320 static struct rpc_cred *
 321 ff_layout_get_mirror_cred(struct nfs4_ff_layout_mirror *mirror, u32 iomode)
 322 {
 323         struct rpc_cred *cred, __rcu **pcred;
 324
 325         if (iomode == IOMODE_READ)
 326                 pcred = &mirror->ro_cred;
 327         else
 328                 pcred = &mirror->rw_cred;
 329
 330         rcu_read_lock();
 331         do {
 332                 cred = rcu_dereference(*pcred);
 333                 if (!cred)
 334                         break;
 335
 336                 cred = get_rpccred_rcu(cred);
 337         } while(!cred);
 338         rcu_read_unlock();
 339         return cred;
 340 }
 341
 342 struct nfs_fh *
 343 nfs4_ff_layout_select_ds_fh(struct pnfs_layout_segment *lseg, u32 mirror_idx)
 344 {
 345         struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, mirror_idx);
 346         struct nfs_fh *fh = NULL;
 347
 348         if (!ff_layout_mirror_valid(lseg, mirror, false)) {
 349                 pr_err_ratelimited("NFS: %s: No data server for mirror offset index %d\n",
 350                         __func__, mirror_idx);
 351                 goto out;
 352         }
 353
 354         /* FIXME: For now assume there is only 1 version available for the DS */
 355         fh = &mirror->fh_versions[0];
 356 out:
 357         return fh;
 358 }
 359
 360 /**
 361  * nfs4_ff_layout_prepare_ds - prepare a DS connection for an RPC call
 362  * @lseg: the layout segment we're operating on
 363  * @ds_idx: index of the DS to use
 364  * @fail_return: return layout on connect failure?
 365  *
 366  * Try to prepare a DS connection to accept an RPC call. This involves
 367  * selecting a mirror to use and connecting the client to it if it's not
 368  * already connected.
 369  *
 370  * Since we only need a single functioning mirror to satisfy a read, we don't
 371  * want to return the layout if there is one. For writes though, any down
 372  * mirror should result in a LAYOUTRETURN. @fail_return is how we distinguish
 373  * between the two cases.
 374  *
 375  * Returns a pointer to a connected DS object on success or NULL on failure.
 376  */
 377 struct nfs4_pnfs_ds *
 378 nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx,
 379                           bool fail_return)
 380 {
 381         struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);
 382         struct nfs4_pnfs_ds *ds = NULL;
 383         struct nfs4_deviceid_node *devid;
 384         struct inode *ino = lseg->pls_layout->plh_inode;
 385         struct nfs_server *s = NFS_SERVER(ino);
 386         unsigned int max_payload;
 387         int status;
 388
 389         if (!ff_layout_mirror_valid(lseg, mirror, true)) {
 390                 pr_err_ratelimited("NFS: %s: No data server for offset index %d\n",
 391                         __func__, ds_idx);
 392                 goto out;
 393         }
 394
 395         devid = &mirror->mirror_ds->id_node;
 396         if (ff_layout_test_devid_unavailable(devid))
 397                 goto out_fail;
 398
 399         ds = mirror->mirror_ds->ds;
 400         /* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */
 401         smp_rmb();
 402         if (ds->ds_clp)
 403                 goto out;
 404
 405         /* FIXME: For now we assume the server sent only one version of NFS
 406          * to use for the DS.
 407          */
 408         status = nfs4_pnfs_ds_connect(s, ds, devid, dataserver_timeo,
 409                              dataserver_retrans,
 410                              mirror->mirror_ds->ds_versions[0].version,
 411                              mirror->mirror_ds->ds_versions[0].minor_version);
 412
 413         /* connect success, check rsize/wsize limit */
 414         if (ds->ds_clp) {
 415                 max_payload =
 416                         nfs_block_size(rpc_max_payload(ds->ds_clp->cl_rpcclient),
 417                                        NULL);
 418                 if (mirror->mirror_ds->ds_versions[0].rsize > max_payload)
 419                         mirror->mirror_ds->ds_versions[0].rsize = max_payload;
 420                 if (mirror->mirror_ds->ds_versions[0].wsize > max_payload)
 421                         mirror->mirror_ds->ds_versions[0].wsize = max_payload;
 422                 goto out;
 423         }
 424 out_fail:
 425         ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout),
 426                                  mirror, lseg->pls_range.offset,
 427                                  lseg->pls_range.length, NFS4ERR_NXIO,
 428                                  OP_ILLEGAL, GFP_NOIO);
 429         if (fail_return || !ff_layout_has_available_ds(lseg))
 430                 pnfs_error_mark_layout_for_return(ino, lseg);
 431         ds = NULL;
 432 out:
 433         return ds;
 434 }
 435
 436 struct rpc_cred *
 437 ff_layout_get_ds_cred(struct pnfs_layout_segment *lseg, u32 ds_idx,
 438                       struct rpc_cred *mdscred)
 439 {
 440         struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);
 441         struct rpc_cred *cred;
 442
 443         if (mirror) {
 444                 cred = ff_layout_get_mirror_cred(mirror, lseg->pls_range.iomode);
 445                 if (!cred)
 446                         cred = get_rpccred(mdscred);
 447         } else {
 448                 cred = get_rpccred(mdscred);
 449         }
 450         return cred;
 451 }
 452
 453 /**
 454 * Find or create a DS rpc client with th MDS server rpc client auth flavor
 455 * in the nfs_client cl_ds_clients list.
 456 */
 457 struct rpc_clnt *
 458 nfs4_ff_find_or_create_ds_client(struct pnfs_layout_segment *lseg, u32 ds_idx,
 459                                  struct nfs_client *ds_clp, struct inode *inode)
 460 {
 461         struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);
 462
 463         switch (mirror->mirror_ds->ds_versions[0].version) {
 464         case 3:
 465                 /* For NFSv3 DS, flavor is set when creating DS connections */
 466                 return ds_clp->cl_rpcclient;
 467         case 4:
 468                 return nfs4_find_or_create_ds_client(ds_clp, inode);
 469         default:
 470                 BUG();
 471         }
 472 }
 473
 474 void ff_layout_free_ds_ioerr(struct list_head *head)
 475 {
 476         struct nfs4_ff_layout_ds_err *err;
 477
 478         while (!list_empty(head)) {
 479                 err = list_first_entry(head,
 480                                 struct nfs4_ff_layout_ds_err,
 481                                 list);
 482                 list_del(&err->list);
 483                 kfree(err);
 484         }
 485 }
 486
 487 /* called with inode i_lock held */
 488 int ff_layout_encode_ds_ioerr(struct xdr_stream *xdr, const struct list_head *head)
 489 {
 490         struct nfs4_ff_layout_ds_err *err;
 491         __be32 *p;
 492
 493         list_for_each_entry(err, head, list) {
 494                 /* offset(8) + length(8) + stateid(NFS4_STATEID_SIZE)
 495                  * + array length + deviceid(NFS4_DEVICEID4_SIZE)
 496                  * + status(4) + opnum(4)
 497                  */
 498                 p = xdr_reserve_space(xdr,
 499                                 28 + NFS4_STATEID_SIZE + NFS4_DEVICEID4_SIZE);
 500                 if (unlikely(!p))
 501                         return -ENOBUFS;
 502                 p = xdr_encode_hyper(p, err->offset);
 503                 p = xdr_encode_hyper(p, err->length);
 504                 p = xdr_encode_opaque_fixed(p, &err->stateid,
 505                                             NFS4_STATEID_SIZE);
 506                 /* Encode 1 error */
 507                 *p++ = cpu_to_be32(1);
 508                 p = xdr_encode_opaque_fixed(p, &err->deviceid,
 509                                             NFS4_DEVICEID4_SIZE);
 510                 *p++ = cpu_to_be32(err->status);
 511                 *p++ = cpu_to_be32(err->opnum);
 512                 dprintk("%s: offset %llu length %llu status %d op %d\n",
 513                         __func__, err->offset, err->length, err->status,
 514                         err->opnum);
 515         }
 516
 517         return 0;
 518 }
 519
 520 static
 521 unsigned int do_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo,
 522                                       const struct pnfs_layout_range *range,
 523                                       struct list_head *head,
 524                                       unsigned int maxnum)
 525 {
 526         struct nfs4_flexfile_layout *flo = FF_LAYOUT_FROM_HDR(lo);
 527         struct inode *inode = lo->plh_inode;
 528         struct nfs4_ff_layout_ds_err *err, *n;
 529         unsigned int ret = 0;
 530
 531         spin_lock(&inode->i_lock);
 532         list_for_each_entry_safe(err, n, &flo->error_list, list) {
 533                 if (!pnfs_is_range_intersecting(err->offset,
 534                                 pnfs_end_offset(err->offset, err->length),
 535                                 range->offset,
 536                                 pnfs_end_offset(range->offset, range->length)))
 537                         continue;
 538                 if (!maxnum)
 539                         break;
 540                 list_move(&err->list, head);
 541                 maxnum--;
 542                 ret++;
 543         }
 544         spin_unlock(&inode->i_lock);
 545         return ret;
 546 }
 547
 548 unsigned int ff_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo,
 549                                       const struct pnfs_layout_range *range,
 550                                       struct list_head *head,
 551                                       unsigned int maxnum)
 552 {
 553         unsigned int ret;
 554
 555         ret = do_layout_fetch_ds_ioerr(lo, range, head, maxnum);
 556         /* If we're over the max, discard all remaining entries */
 557         if (ret == maxnum) {
 558                 LIST_HEAD(discard);
 559                 do_layout_fetch_ds_ioerr(lo, range, &discard, -1);
 560                 ff_layout_free_ds_ioerr(&discard);
 561         }
 562         return ret;
 563 }
 564
 565 static bool ff_read_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) {
 574                         if (!mirror->mirror_ds)
 575                                 return true;
 576                         if (IS_ERR(mirror->mirror_ds))
 577                                 continue;
 578                         devid = &mirror->mirror_ds->id_node;
 579                         if (!ff_layout_test_devid_unavailable(devid))
 580                                 return true;
 581                 }
 582         }
 583
 584         return false;
 585 }
 586
 587 static bool ff_rw_layout_has_available_ds(struct pnfs_layout_segment *lseg)
 588 {
 589         struct nfs4_ff_layout_mirror *mirror;
 590         struct nfs4_deviceid_node *devid;
 591         u32 idx;
 592
 593         for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
 594                 mirror = FF_LAYOUT_COMP(lseg, idx);
 595                 if (!mirror || IS_ERR(mirror->mirror_ds))
 596                         return false;
 597                 if (!mirror->mirror_ds)
 598                         continue;
 599                 devid = &mirror->mirror_ds->id_node;
 600                 if (ff_layout_test_devid_unavailable(devid))
 601                         return false;
 602         }
 603
 604         return FF_LAYOUT_MIRROR_COUNT(lseg) != 0;
 605 }
 606
 607 static bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg)
 608 {
 609         if (lseg->pls_range.iomode == IOMODE_READ)
 610                 return  ff_read_layout_has_available_ds(lseg);
 611         /* Note: RW layout needs all mirrors available */
 612         return ff_rw_layout_has_available_ds(lseg);
 613 }
 614
 615 bool ff_layout_avoid_mds_available_ds(struct pnfs_layout_segment *lseg)
 616 {
 617         return ff_layout_no_fallback_to_mds(lseg) ||
 618                ff_layout_has_available_ds(lseg);
 619 }
 620
 621 bool ff_layout_avoid_read_on_rw(struct pnfs_layout_segment *lseg)
 622 {
 623         return lseg->pls_range.iomode == IOMODE_RW &&
 624                ff_layout_no_read_on_rw(lseg);
 625 }
 626
 627 module_param(dataserver_retrans, uint, 0644);
 628 MODULE_PARM_DESC(dataserver_retrans, "The  number of times the NFSv4.1 client "
 629                         "retries a request before it attempts further "
 630                         " recovery  action.");
 631 module_param(dataserver_timeo, uint, 0644);
 632 MODULE_PARM_DESC(dataserver_timeo, "The time (in tenths of a second) the "
 633                         "NFSv4.1  client  waits for a response from a "
 634                         " data server before it retries an NFS request.");