SAFE public projects git trees. - safe/jmp/linux-2.6/blob - fs/exofs/ios.c

   1 /*
   2  * Copyright (C) 2005, 2006
   3  * Avishay Traeger (avishay@gmail.com)
   4  * Copyright (C) 2008, 2009
   5  * Boaz Harrosh <bharrosh@panasas.com>
   6  *
   7  * This file is part of exofs.
   8  *
   9  * exofs is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation.  Since it is based on ext2, and the only
  12  * valid version of GPL for the Linux kernel is version 2, the only valid
  13  * version of GPL for exofs is version 2.
  14  *
  15  * exofs is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with exofs; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  23  */
  24
  25 #include <scsi/scsi_device.h>
  26 #include <asm/div64.h>
  27
  28 #include "exofs.h"
  29
  30 #define EXOFS_DBGMSG2(M...) do {} while (0)
  31 /* #define EXOFS_DBGMSG2 EXOFS_DBGMSG */
  32
  33 void exofs_make_credential(u8 cred_a[OSD_CAP_LEN], const struct osd_obj_id *obj)
  34 {
  35         osd_sec_init_nosec_doall_caps(cred_a, obj, false, true);
  36 }
  37
  38 int exofs_read_kern(struct osd_dev *od, u8 *cred, struct osd_obj_id *obj,
  39                     u64 offset, void *p, unsigned length)
  40 {
  41         struct osd_request *or = osd_start_request(od, GFP_KERNEL);
  42 /*      struct osd_sense_info osi = {.key = 0};*/
  43         int ret;
  44
  45         if (unlikely(!or)) {
  46                 EXOFS_DBGMSG("%s: osd_start_request failed.\n", __func__);
  47                 return -ENOMEM;
  48         }
  49         ret = osd_req_read_kern(or, obj, offset, p, length);
  50         if (unlikely(ret)) {
  51                 EXOFS_DBGMSG("%s: osd_req_read_kern failed.\n", __func__);
  52                 goto out;
  53         }
  54
  55         ret = osd_finalize_request(or, 0, cred, NULL);
  56         if (unlikely(ret)) {
  57                 EXOFS_DBGMSG("Faild to osd_finalize_request() => %d\n", ret);
  58                 goto out;
  59         }
  60
  61         ret = osd_execute_request(or);
  62         if (unlikely(ret))
  63                 EXOFS_DBGMSG("osd_execute_request() => %d\n", ret);
  64         /* osd_req_decode_sense(or, ret); */
  65
  66 out:
  67         osd_end_request(or);
  68         return ret;
  69 }
  70
  71 int exofs_get_io_state(struct exofs_layout *layout,
  72                        struct exofs_io_state **pios)
  73 {
  74         struct exofs_io_state *ios;
  75
  76         /*TODO: Maybe use kmem_cach per sbi of size
  77          * exofs_io_state_size(layout->s_numdevs)
  78          */
  79         ios = kzalloc(exofs_io_state_size(layout->s_numdevs), GFP_KERNEL);
  80         if (unlikely(!ios)) {
  81                 EXOFS_DBGMSG("Faild kzalloc bytes=%d\n",
  82                              exofs_io_state_size(layout->s_numdevs));
  83                 *pios = NULL;
  84                 return -ENOMEM;
  85         }
  86
  87         ios->layout = layout;
  88         ios->obj.partition = layout->s_pid;
  89         *pios = ios;
  90         return 0;
  91 }
  92
  93 void exofs_put_io_state(struct exofs_io_state *ios)
  94 {
  95         if (ios) {
  96                 unsigned i;
  97
  98                 for (i = 0; i < ios->numdevs; i++) {
  99                         struct exofs_per_dev_state *per_dev = &ios->per_dev[i];
 100
 101                         if (per_dev->or)
 102                                 osd_end_request(per_dev->or);
 103                         if (per_dev->bio)
 104                                 bio_put(per_dev->bio);
 105                 }
 106
 107                 kfree(ios);
 108         }
 109 }
 110
 111 unsigned exofs_layout_od_id(struct exofs_layout *layout,
 112                             osd_id obj_no, unsigned layout_index)
 113 {
 114 /*      switch (layout->lay_func) {
 115         case LAYOUT_MOVING_WINDOW:
 116         {*/
 117                 unsigned dev_mod = obj_no;
 118
 119                 return (layout_index + dev_mod * layout->mirrors_p1) %
 120                                                               layout->s_numdevs;
 121 /*      }
 122         case LAYOUT_FUNC_IMPLICT:
 123                 return layout->devs[layout_index];
 124         }*/
 125 }
 126
 127 static inline struct osd_dev *exofs_ios_od(struct exofs_io_state *ios,
 128                                            unsigned layout_index)
 129 {
 130         return ios->layout->s_ods[
 131                 exofs_layout_od_id(ios->layout, ios->obj.id, layout_index)];
 132 }
 133
 134 static void _sync_done(struct exofs_io_state *ios, void *p)
 135 {
 136         struct completion *waiting = p;
 137
 138         complete(waiting);
 139 }
 140
 141 static void _last_io(struct kref *kref)
 142 {
 143         struct exofs_io_state *ios = container_of(
 144                                         kref, struct exofs_io_state, kref);
 145
 146         ios->done(ios, ios->private);
 147 }
 148
 149 static void _done_io(struct osd_request *or, void *p)
 150 {
 151         struct exofs_io_state *ios = p;
 152
 153         kref_put(&ios->kref, _last_io);
 154 }
 155
 156 static int exofs_io_execute(struct exofs_io_state *ios)
 157 {
 158         DECLARE_COMPLETION_ONSTACK(wait);
 159         bool sync = (ios->done == NULL);
 160         int i, ret;
 161
 162         if (sync) {
 163                 ios->done = _sync_done;
 164                 ios->private = &wait;
 165         }
 166
 167         for (i = 0; i < ios->numdevs; i++) {
 168                 struct osd_request *or = ios->per_dev[i].or;
 169                 if (unlikely(!or))
 170                         continue;
 171
 172                 ret = osd_finalize_request(or, 0, ios->cred, NULL);
 173                 if (unlikely(ret)) {
 174                         EXOFS_DBGMSG("Faild to osd_finalize_request() => %d\n",
 175                                      ret);
 176                         return ret;
 177                 }
 178         }
 179
 180         kref_init(&ios->kref);
 181
 182         for (i = 0; i < ios->numdevs; i++) {
 183                 struct osd_request *or = ios->per_dev[i].or;
 184                 if (unlikely(!or))
 185                         continue;
 186
 187                 kref_get(&ios->kref);
 188                 osd_execute_request_async(or, _done_io, ios);
 189         }
 190
 191         kref_put(&ios->kref, _last_io);
 192         ret = 0;
 193
 194         if (sync) {
 195                 wait_for_completion(&wait);
 196                 ret = exofs_check_io(ios, NULL);
 197         }
 198         return ret;
 199 }
 200
 201 static void _clear_bio(struct bio *bio)
 202 {
 203         struct bio_vec *bv;
 204         unsigned i;
 205
 206         __bio_for_each_segment(bv, bio, i, 0) {
 207                 unsigned this_count = bv->bv_len;
 208
 209                 if (likely(PAGE_SIZE == this_count))
 210                         clear_highpage(bv->bv_page);
 211                 else
 212                         zero_user(bv->bv_page, bv->bv_offset, this_count);
 213         }
 214 }
 215
 216 int exofs_check_io(struct exofs_io_state *ios, u64 *resid)
 217 {
 218         enum osd_err_priority acumulated_osd_err = 0;
 219         int acumulated_lin_err = 0;
 220         int i;
 221
 222         for (i = 0; i < ios->numdevs; i++) {
 223                 struct osd_sense_info osi;
 224                 struct osd_request *or = ios->per_dev[i].or;
 225                 int ret;
 226
 227                 if (unlikely(!or))
 228                         continue;
 229
 230                 ret = osd_req_decode_sense(or, &osi);
 231                 if (likely(!ret))
 232                         continue;
 233
 234                 if (OSD_ERR_PRI_CLEAR_PAGES == osi.osd_err_pri) {
 235                         /* start read offset passed endof file */
 236                         _clear_bio(ios->per_dev[i].bio);
 237                         EXOFS_DBGMSG("start read offset passed end of file "
 238                                 "offset=0x%llx, length=0x%llx\n",
 239                                 _LLU(ios->per_dev[i].offset),
 240                                 _LLU(ios->per_dev[i].length));
 241
 242                         continue; /* we recovered */
 243                 }
 244
 245                 if (osi.osd_err_pri >= acumulated_osd_err) {
 246                         acumulated_osd_err = osi.osd_err_pri;
 247                         acumulated_lin_err = ret;
 248                 }
 249         }
 250
 251         /* TODO: raid specific residual calculations */
 252         if (resid) {
 253                 if (likely(!acumulated_lin_err))
 254                         *resid = 0;
 255                 else
 256                         *resid = ios->length;
 257         }
 258
 259         return acumulated_lin_err;
 260 }
 261
 262 /* REMOVEME: After review
 263    Some quoteing from the standard
 264
 265    L = logical offset into the file
 266    W = number of data components in a stripe
 267    S = W * stripe_unit (S is Stripe length)
 268    N = L / S (N is the stripe Number)
 269    C = (L-(N*S)) / stripe_unit (C is the component)
 270    O = (N*stripe_unit)+(L%stripe_unit) (O is the object's offset)
 271 */
 272
 273 static void _offset_dev_unit_off(struct exofs_io_state *ios, u64 file_offset,
 274                         u64 *obj_offset, unsigned *dev, unsigned *unit_off)
 275 {
 276         unsigned stripe_unit = ios->layout->stripe_unit;
 277         unsigned stripe_length = stripe_unit * ios->layout->group_width;
 278         u64 stripe_no = file_offset;
 279         unsigned stripe_mod = do_div(stripe_no, stripe_length);
 280
 281         *unit_off = stripe_mod % stripe_unit;
 282         *obj_offset = stripe_no * stripe_unit + *unit_off;
 283         *dev = stripe_mod / stripe_unit * ios->layout->mirrors_p1;
 284 }
 285
 286 static int _add_stripe_unit(struct exofs_io_state *ios,  unsigned *cur_pg,
 287                 unsigned pgbase, struct exofs_per_dev_state *per_dev,
 288                 int cur_len)
 289 {
 290         unsigned pg = *cur_pg;
 291         struct request_queue *q =
 292                         osd_request_queue(exofs_ios_od(ios, per_dev->dev));
 293
 294         per_dev->length += cur_len;
 295
 296         if (per_dev->bio == NULL) {
 297                 unsigned pages_in_stripe = ios->layout->group_width *
 298                                         (ios->layout->stripe_unit / PAGE_SIZE);
 299                 unsigned bio_size = (ios->nr_pages + pages_in_stripe) /
 300                                                 ios->layout->group_width;
 301
 302                 per_dev->bio = bio_kmalloc(GFP_KERNEL, bio_size);
 303                 if (unlikely(!per_dev->bio)) {
 304                         EXOFS_DBGMSG("Faild to allocate BIO size=%u\n",
 305                                      bio_size);
 306                         return -ENOMEM;
 307                 }
 308         }
 309
 310         while (cur_len > 0) {
 311                 unsigned pglen = min_t(unsigned, PAGE_SIZE - pgbase, cur_len);
 312                 unsigned added_len;
 313
 314                 BUG_ON(ios->nr_pages <= pg);
 315                 cur_len -= pglen;
 316
 317                 added_len = bio_add_pc_page(q, per_dev->bio, ios->pages[pg],
 318                                             pglen, pgbase);
 319                 if (unlikely(pglen != added_len))
 320                         return -ENOMEM;
 321                 pgbase = 0;
 322                 ++pg;
 323         }
 324         BUG_ON(cur_len);
 325
 326         *cur_pg = pg;
 327         return 0;
 328 }
 329
 330 static int _prepare_for_striping(struct exofs_io_state *ios)
 331 {
 332         u64 length = ios->length;
 333         u64 offset = ios->offset;
 334         unsigned stripe_unit = ios->layout->stripe_unit;
 335         unsigned comp = 0;
 336         unsigned stripes = 0;
 337         unsigned cur_pg = 0;
 338         int ret = 0;
 339
 340         if (!ios->pages) {
 341                 if (ios->kern_buff) {
 342                         struct exofs_per_dev_state *per_dev = &ios->per_dev[0];
 343                         unsigned unit_off;
 344
 345                         _offset_dev_unit_off(ios, offset, &per_dev->offset,
 346                                              &per_dev->dev, &unit_off);
 347                         /* no cross device without page array */
 348                         BUG_ON((ios->layout->group_width > 1) &&
 349                                (unit_off + length > stripe_unit));
 350                 }
 351                 ios->numdevs = ios->layout->mirrors_p1;
 352                 return 0;
 353         }
 354
 355         while (length) {
 356                 struct exofs_per_dev_state *per_dev = &ios->per_dev[comp];
 357                 unsigned cur_len, page_off;
 358
 359                 if (!per_dev->length) {
 360                         unsigned unit_off;
 361
 362                         _offset_dev_unit_off(ios, offset, &per_dev->offset,
 363                                              &per_dev->dev, &unit_off);
 364                         stripes++;
 365                         cur_len = min_t(u64, stripe_unit - unit_off, length);
 366                         offset += cur_len;
 367                         page_off = unit_off & ~PAGE_MASK;
 368                         BUG_ON(page_off != ios->pgbase);
 369                 } else {
 370                         cur_len = min_t(u64, stripe_unit, length);
 371                         page_off = 0;
 372                 }
 373
 374                 ret = _add_stripe_unit(ios, &cur_pg, page_off , per_dev,
 375                                        cur_len);
 376                 if (unlikely(ret))
 377                         goto out;
 378
 379                 comp += ios->layout->mirrors_p1;
 380                 comp %= ios->layout->s_numdevs;
 381
 382                 length -= cur_len;
 383         }
 384 out:
 385         ios->numdevs = stripes * ios->layout->mirrors_p1;
 386         return ret;
 387 }
 388
 389 int exofs_sbi_create(struct exofs_io_state *ios)
 390 {
 391         int i, ret;
 392
 393         for (i = 0; i < ios->layout->s_numdevs; i++) {
 394                 struct osd_request *or;
 395
 396                 or = osd_start_request(exofs_ios_od(ios, i), GFP_KERNEL);
 397                 if (unlikely(!or)) {
 398                         EXOFS_ERR("%s: osd_start_request failed\n", __func__);
 399                         ret = -ENOMEM;
 400                         goto out;
 401                 }
 402                 ios->per_dev[i].or = or;
 403                 ios->numdevs++;
 404
 405                 osd_req_create_object(or, &ios->obj);
 406         }
 407         ret = exofs_io_execute(ios);
 408
 409 out:
 410         return ret;
 411 }
 412
 413 int exofs_sbi_remove(struct exofs_io_state *ios)
 414 {
 415         int i, ret;
 416
 417         for (i = 0; i < ios->layout->s_numdevs; i++) {
 418                 struct osd_request *or;
 419
 420                 or = osd_start_request(exofs_ios_od(ios, i), GFP_KERNEL);
 421                 if (unlikely(!or)) {
 422                         EXOFS_ERR("%s: osd_start_request failed\n", __func__);
 423                         ret = -ENOMEM;
 424                         goto out;
 425                 }
 426                 ios->per_dev[i].or = or;
 427                 ios->numdevs++;
 428
 429                 osd_req_remove_object(or, &ios->obj);
 430         }
 431         ret = exofs_io_execute(ios);
 432
 433 out:
 434         return ret;
 435 }
 436
 437 static int _sbi_write_mirror(struct exofs_io_state *ios, int cur_comp)
 438 {
 439         struct exofs_per_dev_state *master_dev = &ios->per_dev[cur_comp];
 440         unsigned dev = ios->per_dev[cur_comp].dev;
 441         unsigned last_comp = cur_comp + ios->layout->mirrors_p1;
 442         int ret = 0;
 443
 444         for (; cur_comp < last_comp; ++cur_comp, ++dev) {
 445                 struct exofs_per_dev_state *per_dev = &ios->per_dev[cur_comp];
 446                 struct osd_request *or;
 447
 448                 or = osd_start_request(exofs_ios_od(ios, dev), GFP_KERNEL);
 449                 if (unlikely(!or)) {
 450                         EXOFS_ERR("%s: osd_start_request failed\n", __func__);
 451                         ret = -ENOMEM;
 452                         goto out;
 453                 }
 454                 per_dev->or = or;
 455                 per_dev->offset = master_dev->offset;
 456
 457                 if (ios->pages) {
 458                         struct bio *bio;
 459
 460                         if (per_dev != master_dev) {
 461                                 bio = bio_kmalloc(GFP_KERNEL,
 462                                                   master_dev->bio->bi_max_vecs);
 463                                 if (unlikely(!bio)) {
 464                                         EXOFS_DBGMSG(
 465                                               "Faild to allocate BIO size=%u\n",
 466                                               master_dev->bio->bi_max_vecs);
 467                                         ret = -ENOMEM;
 468                                         goto out;
 469                                 }
 470
 471                                 __bio_clone(bio, master_dev->bio);
 472                                 bio->bi_bdev = NULL;
 473                                 bio->bi_next = NULL;
 474                                 per_dev->length = master_dev->length;
 475                                 per_dev->bio =  bio;
 476                                 per_dev->dev = dev;
 477                         } else {
 478                                 bio = master_dev->bio;
 479                                 /* FIXME: bio_set_dir() */
 480                                 bio->bi_rw |= (1 << BIO_RW);
 481                         }
 482
 483                         osd_req_write(or, &ios->obj, per_dev->offset, bio,
 484                                       per_dev->length);
 485                         EXOFS_DBGMSG("write(0x%llx) offset=0x%llx "
 486                                       "length=0x%llx dev=%d\n",
 487                                      _LLU(ios->obj.id), _LLU(per_dev->offset),
 488                                      _LLU(per_dev->length), dev);
 489                 } else if (ios->kern_buff) {
 490                         ret = osd_req_write_kern(or, &ios->obj, per_dev->offset,
 491                                            ios->kern_buff, ios->length);
 492                         if (unlikely(ret))
 493                                 goto out;
 494                         EXOFS_DBGMSG2("write_kern(0x%llx) offset=0x%llx "
 495                                       "length=0x%llx dev=%d\n",
 496                                      _LLU(ios->obj.id), _LLU(per_dev->offset),
 497                                      _LLU(ios->length), dev);
 498                 } else {
 499                         osd_req_set_attributes(or, &ios->obj);
 500                         EXOFS_DBGMSG2("obj(0x%llx) set_attributes=%d dev=%d\n",
 501                                      _LLU(ios->obj.id), ios->out_attr_len, dev);
 502                 }
 503
 504                 if (ios->out_attr)
 505                         osd_req_add_set_attr_list(or, ios->out_attr,
 506                                                   ios->out_attr_len);
 507
 508                 if (ios->in_attr)
 509                         osd_req_add_get_attr_list(or, ios->in_attr,
 510                                                   ios->in_attr_len);
 511         }
 512
 513 out:
 514         return ret;
 515 }
 516
 517 int exofs_sbi_write(struct exofs_io_state *ios)
 518 {
 519         int i;
 520         int ret;
 521
 522         ret = _prepare_for_striping(ios);
 523         if (unlikely(ret))
 524                 return ret;
 525
 526         for (i = 0; i < ios->numdevs; i += ios->layout->mirrors_p1) {
 527                 ret = _sbi_write_mirror(ios, i);
 528                 if (unlikely(ret))
 529                         return ret;
 530         }
 531
 532         ret = exofs_io_execute(ios);
 533         return ret;
 534 }
 535
 536 static int _sbi_read_mirror(struct exofs_io_state *ios, unsigned cur_comp)
 537 {
 538         struct osd_request *or;
 539         struct exofs_per_dev_state *per_dev = &ios->per_dev[cur_comp];
 540         unsigned first_dev = (unsigned)ios->obj.id;
 541
 542         first_dev = per_dev->dev + first_dev % ios->layout->mirrors_p1;
 543         or = osd_start_request(exofs_ios_od(ios, first_dev), GFP_KERNEL);
 544         if (unlikely(!or)) {
 545                 EXOFS_ERR("%s: osd_start_request failed\n", __func__);
 546                 return -ENOMEM;
 547         }
 548         per_dev->or = or;
 549
 550         if (ios->pages) {
 551                 osd_req_read(or, &ios->obj, per_dev->offset,
 552                                 per_dev->bio, per_dev->length);
 553                 EXOFS_DBGMSG("read(0x%llx) offset=0x%llx length=0x%llx"
 554                              " dev=%d\n", _LLU(ios->obj.id),
 555                              _LLU(per_dev->offset), _LLU(per_dev->length),
 556                              first_dev);
 557         } else if (ios->kern_buff) {
 558                 int ret = osd_req_read_kern(or, &ios->obj, per_dev->offset,
 559                                             ios->kern_buff, ios->length);
 560                 EXOFS_DBGMSG2("read_kern(0x%llx) offset=0x%llx "
 561                               "length=0x%llx dev=%d ret=>%d\n",
 562                               _LLU(ios->obj.id), _LLU(per_dev->offset),
 563                               _LLU(ios->length), first_dev, ret);
 564                 if (unlikely(ret))
 565                         return ret;
 566         } else {
 567                 osd_req_get_attributes(or, &ios->obj);
 568                 EXOFS_DBGMSG2("obj(0x%llx) get_attributes=%d dev=%d\n",
 569                               _LLU(ios->obj.id), ios->in_attr_len, first_dev);
 570         }
 571         if (ios->out_attr)
 572                 osd_req_add_set_attr_list(or, ios->out_attr, ios->out_attr_len);
 573
 574         if (ios->in_attr)
 575                 osd_req_add_get_attr_list(or, ios->in_attr, ios->in_attr_len);
 576
 577         return 0;
 578 }
 579
 580 int exofs_sbi_read(struct exofs_io_state *ios)
 581 {
 582         int i;
 583         int ret;
 584
 585         ret = _prepare_for_striping(ios);
 586         if (unlikely(ret))
 587                 return ret;
 588
 589         for (i = 0; i < ios->numdevs; i += ios->layout->mirrors_p1) {
 590                 ret = _sbi_read_mirror(ios, i);
 591                 if (unlikely(ret))
 592                         return ret;
 593         }
 594
 595         ret = exofs_io_execute(ios);
 596         return ret;
 597 }
 598
 599 int extract_attr_from_ios(struct exofs_io_state *ios, struct osd_attr *attr)
 600 {
 601         struct osd_attr cur_attr = {.attr_page = 0}; /* start with zeros */
 602         void *iter = NULL;
 603         int nelem;
 604
 605         do {
 606                 nelem = 1;
 607                 osd_req_decode_get_attr_list(ios->per_dev[0].or,
 608                                              &cur_attr, &nelem, &iter);
 609                 if ((cur_attr.attr_page == attr->attr_page) &&
 610                     (cur_attr.attr_id == attr->attr_id)) {
 611                         attr->len = cur_attr.len;
 612                         attr->val_ptr = cur_attr.val_ptr;
 613                         return 0;
 614                 }
 615         } while (iter);
 616
 617         return -EIO;
 618 }
 619
 620 static int _truncate_mirrors(struct exofs_io_state *ios, unsigned cur_comp,
 621                              struct osd_attr *attr)
 622 {
 623         int last_comp = cur_comp + ios->layout->mirrors_p1;
 624
 625         for (; cur_comp < last_comp; ++cur_comp) {
 626                 struct exofs_per_dev_state *per_dev = &ios->per_dev[cur_comp];
 627                 struct osd_request *or;
 628
 629                 or = osd_start_request(exofs_ios_od(ios, cur_comp), GFP_KERNEL);
 630                 if (unlikely(!or)) {
 631                         EXOFS_ERR("%s: osd_start_request failed\n", __func__);
 632                         return -ENOMEM;
 633                 }
 634                 per_dev->or = or;
 635
 636                 osd_req_set_attributes(or, &ios->obj);
 637                 osd_req_add_set_attr_list(or, attr, 1);
 638         }
 639
 640         return 0;
 641 }
 642
 643 int exofs_oi_truncate(struct exofs_i_info *oi, u64 size)
 644 {
 645         struct exofs_sb_info *sbi = oi->vfs_inode.i_sb->s_fs_info;
 646         struct exofs_io_state *ios;
 647         struct exofs_trunc_attr {
 648                 struct osd_attr attr;
 649                 __be64 newsize;
 650         } *size_attrs;
 651         u64 this_obj_size;
 652         unsigned dev;
 653         unsigned unit_off;
 654         int i, ret;
 655
 656         ret = exofs_get_io_state(&sbi->layout, &ios);
 657         if (unlikely(ret))
 658                 return ret;
 659
 660         size_attrs = kcalloc(ios->layout->group_width, sizeof(*size_attrs),
 661                              GFP_KERNEL);
 662         if (unlikely(!size_attrs)) {
 663                 ret = -ENOMEM;
 664                 goto out;
 665         }
 666
 667         ios->obj.id = exofs_oi_objno(oi);
 668         ios->cred = oi->i_cred;
 669
 670         ios->numdevs = ios->layout->s_numdevs;
 671         _offset_dev_unit_off(ios, size, &this_obj_size, &dev, &unit_off);
 672
 673         for (i = 0; i < ios->layout->group_width; ++i) {
 674                 struct exofs_trunc_attr *size_attr = &size_attrs[i];
 675                 u64 obj_size;
 676
 677                 if (i < dev)
 678                         obj_size = this_obj_size +
 679                                         ios->layout->stripe_unit - unit_off;
 680                 else if (i == dev)
 681                         obj_size = this_obj_size;
 682                 else /* i > dev */
 683                         obj_size = this_obj_size - unit_off;
 684
 685                 size_attr->newsize = cpu_to_be64(obj_size);
 686                 size_attr->attr = g_attr_logical_length;
 687                 size_attr->attr.val_ptr = &size_attr->newsize;
 688
 689                 ret = _truncate_mirrors(ios, i * ios->layout->mirrors_p1,
 690                                         &size_attr->attr);
 691                 if (unlikely(ret))
 692                         goto out;
 693         }
 694         ret = exofs_io_execute(ios);
 695
 696 out:
 697         kfree(size_attrs);
 698         exofs_put_io_state(ios);
 699         return ret;
 700 }