kernel/fs/quota/quota_tree.c

   1 /*
   2  *      vfsv0 quota IO operations on file
   3  */
   4
   5 #include <linux/errno.h>
   6 #include <linux/fs.h>
   7 #include <linux/mount.h>
   8 #include <linux/dqblk_v2.h>
   9 #include <linux/kernel.h>
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/quotaops.h>
  14
  15 #include <asm/byteorder.h>
  16
  17 #include "quota_tree.h"
  18
  19 MODULE_AUTHOR("Jan Kara");
  20 MODULE_DESCRIPTION("Quota trie support");
  21 MODULE_LICENSE("GPL");
  22
  23 #define __QUOTA_QT_PARANOIA
  24
  25 static int get_index(struct qtree_mem_dqinfo *info, struct kqid qid, int depth)
  26 {
  27         unsigned int epb = info->dqi_usable_bs >> 2;
  28         qid_t id = from_kqid(&init_user_ns, qid);
  29
  30         depth = info->dqi_qtree_depth - depth - 1;
  31         while (depth--)
  32                 id /= epb;
  33         return id % epb;
  34 }
  35
  36 /* Number of entries in one blocks */
  37 static int qtree_dqstr_in_blk(struct qtree_mem_dqinfo *info)
  38 {
  39         return (info->dqi_usable_bs - sizeof(struct qt_disk_dqdbheader))
  40                / info->dqi_entry_size;
  41 }
  42
  43 static char *getdqbuf(size_t size)
  44 {
  45         char *buf = kmalloc(size, GFP_NOFS);
  46         if (!buf)
  47                 printk(KERN_WARNING
  48                        "VFS: Not enough memory for quota buffers.\n");
  49         return buf;
  50 }
  51
  52 static ssize_t read_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)
  53 {
  54         struct super_block *sb = info->dqi_sb;
  55
  56         memset(buf, 0, info->dqi_usable_bs);
  57         return sb->s_op->quota_read(sb, info->dqi_type, buf,
  58                info->dqi_usable_bs, blk << info->dqi_blocksize_bits);
  59 }
  60
  61 static ssize_t write_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)
  62 {
  63         struct super_block *sb = info->dqi_sb;
  64         ssize_t ret;
  65
  66         ret = sb->s_op->quota_write(sb, info->dqi_type, buf,
  67                info->dqi_usable_bs, blk << info->dqi_blocksize_bits);
  68         if (ret != info->dqi_usable_bs) {
  69                 quota_error(sb, "dquota write failed");
  70                 if (ret >= 0)
  71                         ret = -EIO;
  72         }
  73         return ret;
  74 }
  75
  76 /* Remove empty block from list and return it */
  77 static int get_free_dqblk(struct qtree_mem_dqinfo *info)
  78 {
  79         char *buf = getdqbuf(info->dqi_usable_bs);
  80         struct qt_disk_dqdbheader *dh = (struct qt_disk_dqdbheader *)buf;
  81         int ret, blk;
  82
  83         if (!buf)
  84                 return -ENOMEM;
  85         if (info->dqi_free_blk) {
  86                 blk = info->dqi_free_blk;
  87                 ret = read_blk(info, blk, buf);
  88                 if (ret < 0)
  89                         goto out_buf;
  90                 info->dqi_free_blk = le32_to_cpu(dh->dqdh_next_free);
  91         }
  92         else {
  93                 memset(buf, 0, info->dqi_usable_bs);
  94                 /* Assure block allocation... */
  95                 ret = write_blk(info, info->dqi_blocks, buf);
  96                 if (ret < 0)
  97                         goto out_buf;
  98                 blk = info->dqi_blocks++;
  99         }
 100         mark_info_dirty(info->dqi_sb, info->dqi_type);
 101         ret = blk;
 102 out_buf:
 103         kfree(buf);
 104         return ret;
 105 }
 106
 107 /* Insert empty block to the list */
 108 static int put_free_dqblk(struct qtree_mem_dqinfo *info, char *buf, uint blk)
 109 {
 110         struct qt_disk_dqdbheader *dh = (struct qt_disk_dqdbheader *)buf;
 111         int err;
 112
 113         dh->dqdh_next_free = cpu_to_le32(info->dqi_free_blk);
 114         dh->dqdh_prev_free = cpu_to_le32(0);
 115         dh->dqdh_entries = cpu_to_le16(0);
 116         err = write_blk(info, blk, buf);
 117         if (err < 0)
 118                 return err;
 119         info->dqi_free_blk = blk;
 120         mark_info_dirty(info->dqi_sb, info->dqi_type);
 121         return 0;
 122 }
 123
 124 /* Remove given block from the list of blocks with free entries */
 125 static int remove_free_dqentry(struct qtree_mem_dqinfo *info, char *buf,
 126                                uint blk)
 127 {
 128         char *tmpbuf = getdqbuf(info->dqi_usable_bs);
 129         struct qt_disk_dqdbheader *dh = (struct qt_disk_dqdbheader *)buf;
 130         uint nextblk = le32_to_cpu(dh->dqdh_next_free);
 131         uint prevblk = le32_to_cpu(dh->dqdh_prev_free);
 132         int err;
 133
 134         if (!tmpbuf)
 135                 return -ENOMEM;
 136         if (nextblk) {
 137                 err = read_blk(info, nextblk, tmpbuf);
 138                 if (err < 0)
 139                         goto out_buf;
 140                 ((struct qt_disk_dqdbheader *)tmpbuf)->dqdh_prev_free =
 141                                                         dh->dqdh_prev_free;
 142                 err = write_blk(info, nextblk, tmpbuf);
 143                 if (err < 0)
 144                         goto out_buf;
 145         }
 146         if (prevblk) {
 147                 err = read_blk(info, prevblk, tmpbuf);
 148                 if (err < 0)
 149                         goto out_buf;
 150                 ((struct qt_disk_dqdbheader *)tmpbuf)->dqdh_next_free =
 151                                                         dh->dqdh_next_free;
 152                 err = write_blk(info, prevblk, tmpbuf);
 153                 if (err < 0)
 154                         goto out_buf;
 155         } else {
 156                 info->dqi_free_entry = nextblk;
 157                 mark_info_dirty(info->dqi_sb, info->dqi_type);
 158         }
 159         kfree(tmpbuf);
 160         dh->dqdh_next_free = dh->dqdh_prev_free = cpu_to_le32(0);
 161         /* No matter whether write succeeds block is out of list */
 162         if (write_blk(info, blk, buf) < 0)
 163                 quota_error(info->dqi_sb, "Can't write block (%u) "
 164                             "with free entries", blk);
 165         return 0;
 166 out_buf:
 167         kfree(tmpbuf);
 168         return err;
 169 }
 170
 171 /* Insert given block to the beginning of list with free entries */
 172 static int insert_free_dqentry(struct qtree_mem_dqinfo *info, char *buf,
 173                                uint blk)
 174 {
 175         char *tmpbuf = getdqbuf(info->dqi_usable_bs);
 176         struct qt_disk_dqdbheader *dh = (struct qt_disk_dqdbheader *)buf;
 177         int err;
 178
 179         if (!tmpbuf)
 180                 return -ENOMEM;
 181         dh->dqdh_next_free = cpu_to_le32(info->dqi_free_entry);
 182         dh->dqdh_prev_free = cpu_to_le32(0);
 183         err = write_blk(info, blk, buf);
 184         if (err < 0)
 185                 goto out_buf;
 186         if (info->dqi_free_entry) {
 187                 err = read_blk(info, info->dqi_free_entry, tmpbuf);
 188                 if (err < 0)
 189                         goto out_buf;
 190                 ((struct qt_disk_dqdbheader *)tmpbuf)->dqdh_prev_free =
 191                                                         cpu_to_le32(blk);
 192                 err = write_blk(info, info->dqi_free_entry, tmpbuf);
 193                 if (err < 0)
 194                         goto out_buf;
 195         }
 196         kfree(tmpbuf);
 197         info->dqi_free_entry = blk;
 198         mark_info_dirty(info->dqi_sb, info->dqi_type);
 199         return 0;
 200 out_buf:
 201         kfree(tmpbuf);
 202         return err;
 203 }
 204
 205 /* Is the entry in the block free? */
 206 int qtree_entry_unused(struct qtree_mem_dqinfo *info, char *disk)
 207 {
 208         int i;
 209
 210         for (i = 0; i < info->dqi_entry_size; i++)
 211                 if (disk[i])
 212                         return 0;
 213         return 1;
 214 }
 215 EXPORT_SYMBOL(qtree_entry_unused);
 216
 217 /* Find space for dquot */
 218 static uint find_free_dqentry(struct qtree_mem_dqinfo *info,
 219                               struct dquot *dquot, int *err)
 220 {
 221         uint blk, i;
 222         struct qt_disk_dqdbheader *dh;
 223         char *buf = getdqbuf(info->dqi_usable_bs);
 224         char *ddquot;
 225
 226         *err = 0;
 227         if (!buf) {
 228                 *err = -ENOMEM;
 229                 return 0;
 230         }
 231         dh = (struct qt_disk_dqdbheader *)buf;
 232         if (info->dqi_free_entry) {
 233                 blk = info->dqi_free_entry;
 234                 *err = read_blk(info, blk, buf);
 235                 if (*err < 0)
 236                         goto out_buf;
 237         } else {
 238                 blk = get_free_dqblk(info);
 239                 if ((int)blk < 0) {
 240                         *err = blk;
 241                         kfree(buf);
 242                         return 0;
 243                 }
 244                 memset(buf, 0, info->dqi_usable_bs);
 245                 /* This is enough as the block is already zeroed and the entry
 246                  * list is empty... */
 247                 info->dqi_free_entry = blk;
 248                 mark_info_dirty(dquot->dq_sb, dquot->dq_id.type);
 249         }
 250         /* Block will be full? */
 251         if (le16_to_cpu(dh->dqdh_entries) + 1 >= qtree_dqstr_in_blk(info)) {
 252                 *err = remove_free_dqentry(info, buf, blk);
 253                 if (*err < 0) {
 254                         quota_error(dquot->dq_sb, "Can't remove block (%u) "
 255                                     "from entry free list", blk);
 256                         goto out_buf;
 257                 }
 258         }
 259         le16_add_cpu(&dh->dqdh_entries, 1);
 260         /* Find free structure in block */
 261         ddquot = buf + sizeof(struct qt_disk_dqdbheader);
 262         for (i = 0; i < qtree_dqstr_in_blk(info); i++) {
 263                 if (qtree_entry_unused(info, ddquot))
 264                         break;
 265                 ddquot += info->dqi_entry_size;
 266         }
 267 #ifdef __QUOTA_QT_PARANOIA
 268         if (i == qtree_dqstr_in_blk(info)) {
 269                 quota_error(dquot->dq_sb, "Data block full but it shouldn't");
 270                 *err = -EIO;
 271                 goto out_buf;
 272         }
 273 #endif
 274         *err = write_blk(info, blk, buf);
 275         if (*err < 0) {
 276                 quota_error(dquot->dq_sb, "Can't write quota data block %u",
 277                             blk);
 278                 goto out_buf;
 279         }
 280         dquot->dq_off = (blk << info->dqi_blocksize_bits) +
 281                         sizeof(struct qt_disk_dqdbheader) +
 282                         i * info->dqi_entry_size;
 283         kfree(buf);
 284         return blk;
 285 out_buf:
 286         kfree(buf);
 287         return 0;
 288 }
 289
 290 /* Insert reference to structure into the trie */
 291 static int do_insert_tree(struct qtree_mem_dqinfo *info, struct dquot *dquot,
 292                           uint *treeblk, int depth)
 293 {
 294         char *buf = getdqbuf(info->dqi_usable_bs);
 295         int ret = 0, newson = 0, newact = 0;
 296         __le32 *ref;
 297         uint newblk;
 298
 299         if (!buf)
 300                 return -ENOMEM;
 301         if (!*treeblk) {
 302                 ret = get_free_dqblk(info);
 303                 if (ret < 0)
 304                         goto out_buf;
 305                 *treeblk = ret;
 306                 memset(buf, 0, info->dqi_usable_bs);
 307                 newact = 1;
 308         } else {
 309                 ret = read_blk(info, *treeblk, buf);
 310                 if (ret < 0) {
 311                         quota_error(dquot->dq_sb, "Can't read tree quota "
 312                                     "block %u", *treeblk);
 313                         goto out_buf;
 314                 }
 315         }
 316         ref = (__le32 *)buf;
 317         newblk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
 318         if (!newblk)
 319                 newson = 1;
 320         if (depth == info->dqi_qtree_depth - 1) {
 321 #ifdef __QUOTA_QT_PARANOIA
 322                 if (newblk) {
 323                         quota_error(dquot->dq_sb, "Inserting already present "
 324                                     "quota entry (block %u)",
 325                                     le32_to_cpu(ref[get_index(info,
 326                                                 dquot->dq_id, depth)]));
 327                         ret = -EIO;
 328                         goto out_buf;
 329                 }
 330 #endif
 331                 newblk = find_free_dqentry(info, dquot, &ret);
 332         } else {
 333                 ret = do_insert_tree(info, dquot, &newblk, depth+1);
 334         }
 335         if (newson && ret >= 0) {
 336                 ref[get_index(info, dquot->dq_id, depth)] =
 337                                                         cpu_to_le32(newblk);
 338                 ret = write_blk(info, *treeblk, buf);
 339         } else if (newact && ret < 0) {
 340                 put_free_dqblk(info, buf, *treeblk);
 341         }
 342 out_buf:
 343         kfree(buf);
 344         return ret;
 345 }
 346
 347 /* Wrapper for inserting quota structure into tree */
 348 static inline int dq_insert_tree(struct qtree_mem_dqinfo *info,
 349                                  struct dquot *dquot)
 350 {
 351         int tmp = QT_TREEOFF;
 352
 353 #ifdef __QUOTA_QT_PARANOIA
 354         if (info->dqi_blocks <= QT_TREEOFF) {
 355                 quota_error(dquot->dq_sb, "Quota tree root isn't allocated!");
 356                 return -EIO;
 357         }
 358 #endif
 359         return do_insert_tree(info, dquot, &tmp, 0);
 360 }
 361
 362 /*
 363  * We don't have to be afraid of deadlocks as we never have quotas on quota
 364  * files...
 365  */
 366 int qtree_write_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot)
 367 {
 368         int type = dquot->dq_id.type;
 369         struct super_block *sb = dquot->dq_sb;
 370         ssize_t ret;
 371         char *ddquot = getdqbuf(info->dqi_entry_size);
 372
 373         if (!ddquot)
 374                 return -ENOMEM;
 375
 376         /* dq_off is guarded by dqio_mutex */
 377         if (!dquot->dq_off) {
 378                 ret = dq_insert_tree(info, dquot);
 379                 if (ret < 0) {
 380                         quota_error(sb, "Error %zd occurred while creating "
 381                                     "quota", ret);
 382                         kfree(ddquot);
 383                         return ret;
 384                 }
 385         }
 386         spin_lock(&dq_data_lock);
 387         info->dqi_ops->mem2disk_dqblk(ddquot, dquot);
 388         spin_unlock(&dq_data_lock);
 389         ret = sb->s_op->quota_write(sb, type, ddquot, info->dqi_entry_size,
 390                                     dquot->dq_off);
 391         if (ret != info->dqi_entry_size) {
 392                 quota_error(sb, "dquota write failed");
 393                 if (ret >= 0)
 394                         ret = -ENOSPC;
 395         } else {
 396                 ret = 0;
 397         }
 398         dqstats_inc(DQST_WRITES);
 399         kfree(ddquot);
 400
 401         return ret;
 402 }
 403 EXPORT_SYMBOL(qtree_write_dquot);
 404
 405 /* Free dquot entry in data block */
 406 static int free_dqentry(struct qtree_mem_dqinfo *info, struct dquot *dquot,
 407                         uint blk)
 408 {
 409         struct qt_disk_dqdbheader *dh;
 410         char *buf = getdqbuf(info->dqi_usable_bs);
 411         int ret = 0;
 412
 413         if (!buf)
 414                 return -ENOMEM;
 415         if (dquot->dq_off >> info->dqi_blocksize_bits != blk) {
 416                 quota_error(dquot->dq_sb, "Quota structure has offset to "
 417                         "other block (%u) than it should (%u)", blk,
 418                         (uint)(dquot->dq_off >> info->dqi_blocksize_bits));
 419                 goto out_buf;
 420         }
 421         ret = read_blk(info, blk, buf);
 422         if (ret < 0) {
 423                 quota_error(dquot->dq_sb, "Can't read quota data block %u",
 424                             blk);
 425                 goto out_buf;
 426         }
 427         dh = (struct qt_disk_dqdbheader *)buf;
 428         le16_add_cpu(&dh->dqdh_entries, -1);
 429         if (!le16_to_cpu(dh->dqdh_entries)) {   /* Block got free? */
 430                 ret = remove_free_dqentry(info, buf, blk);
 431                 if (ret >= 0)
 432                         ret = put_free_dqblk(info, buf, blk);
 433                 if (ret < 0) {
 434                         quota_error(dquot->dq_sb, "Can't move quota data block "
 435                                     "(%u) to free list", blk);
 436                         goto out_buf;
 437                 }
 438         } else {
 439                 memset(buf +
 440                        (dquot->dq_off & ((1 << info->dqi_blocksize_bits) - 1)),
 441                        0, info->dqi_entry_size);
 442                 if (le16_to_cpu(dh->dqdh_entries) ==
 443                     qtree_dqstr_in_blk(info) - 1) {
 444                         /* Insert will write block itself */
 445                         ret = insert_free_dqentry(info, buf, blk);
 446                         if (ret < 0) {
 447                                 quota_error(dquot->dq_sb, "Can't insert quota "
 448                                     "data block (%u) to free entry list", blk);
 449                                 goto out_buf;
 450                         }
 451                 } else {
 452                         ret = write_blk(info, blk, buf);
 453                         if (ret < 0) {
 454                                 quota_error(dquot->dq_sb, "Can't write quota "
 455                                             "data block %u", blk);
 456                                 goto out_buf;
 457                         }
 458                 }
 459         }
 460         dquot->dq_off = 0;      /* Quota is now unattached */
 461 out_buf:
 462         kfree(buf);
 463         return ret;
 464 }
 465
 466 /* Remove reference to dquot from tree */
 467 static int remove_tree(struct qtree_mem_dqinfo *info, struct dquot *dquot,
 468                        uint *blk, int depth)
 469 {
 470         char *buf = getdqbuf(info->dqi_usable_bs);
 471         int ret = 0;
 472         uint newblk;
 473         __le32 *ref = (__le32 *)buf;
 474
 475         if (!buf)
 476                 return -ENOMEM;
 477         ret = read_blk(info, *blk, buf);
 478         if (ret < 0) {
 479                 quota_error(dquot->dq_sb, "Can't read quota data block %u",
 480                             *blk);
 481                 goto out_buf;
 482         }
 483         newblk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
 484         if (depth == info->dqi_qtree_depth - 1) {
 485                 ret = free_dqentry(info, dquot, newblk);
 486                 newblk = 0;
 487         } else {
 488                 ret = remove_tree(info, dquot, &newblk, depth+1);
 489         }
 490         if (ret >= 0 && !newblk) {
 491                 int i;
 492                 ref[get_index(info, dquot->dq_id, depth)] = cpu_to_le32(0);
 493                 /* Block got empty? */
 494                 for (i = 0; i < (info->dqi_usable_bs >> 2) && !ref[i]; i++)
 495                         ;
 496                 /* Don't put the root block into the free block list */
 497                 if (i == (info->dqi_usable_bs >> 2)
 498                     && *blk != QT_TREEOFF) {
 499                         put_free_dqblk(info, buf, *blk);
 500                         *blk = 0;
 501                 } else {
 502                         ret = write_blk(info, *blk, buf);
 503                         if (ret < 0)
 504                                 quota_error(dquot->dq_sb,
 505                                             "Can't write quota tree block %u",
 506                                             *blk);
 507                 }
 508         }
 509 out_buf:
 510         kfree(buf);
 511         return ret;
 512 }
 513
 514 /* Delete dquot from tree */
 515 int qtree_delete_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot)
 516 {
 517         uint tmp = QT_TREEOFF;
 518
 519         if (!dquot->dq_off)     /* Even not allocated? */
 520                 return 0;
 521         return remove_tree(info, dquot, &tmp, 0);
 522 }
 523 EXPORT_SYMBOL(qtree_delete_dquot);
 524
 525 /* Find entry in block */
 526 static loff_t find_block_dqentry(struct qtree_mem_dqinfo *info,
 527                                  struct dquot *dquot, uint blk)
 528 {
 529         char *buf = getdqbuf(info->dqi_usable_bs);
 530         loff_t ret = 0;
 531         int i;
 532         char *ddquot;
 533
 534         if (!buf)
 535                 return -ENOMEM;
 536         ret = read_blk(info, blk, buf);
 537         if (ret < 0) {
 538                 quota_error(dquot->dq_sb, "Can't read quota tree "
 539                             "block %u", blk);
 540                 goto out_buf;
 541         }
 542         ddquot = buf + sizeof(struct qt_disk_dqdbheader);
 543         for (i = 0; i < qtree_dqstr_in_blk(info); i++) {
 544                 if (info->dqi_ops->is_id(ddquot, dquot))
 545                         break;
 546                 ddquot += info->dqi_entry_size;
 547         }
 548         if (i == qtree_dqstr_in_blk(info)) {
 549                 quota_error(dquot->dq_sb,
 550                             "Quota for id %u referenced but not present",
 551                             from_kqid(&init_user_ns, dquot->dq_id));
 552                 ret = -EIO;
 553                 goto out_buf;
 554         } else {
 555                 ret = (blk << info->dqi_blocksize_bits) + sizeof(struct
 556                   qt_disk_dqdbheader) + i * info->dqi_entry_size;
 557         }
 558 out_buf:
 559         kfree(buf);
 560         return ret;
 561 }
 562
 563 /* Find entry for given id in the tree */
 564 static loff_t find_tree_dqentry(struct qtree_mem_dqinfo *info,
 565                                 struct dquot *dquot, uint blk, int depth)
 566 {
 567         char *buf = getdqbuf(info->dqi_usable_bs);
 568         loff_t ret = 0;
 569         __le32 *ref = (__le32 *)buf;
 570
 571         if (!buf)
 572                 return -ENOMEM;
 573         ret = read_blk(info, blk, buf);
 574         if (ret < 0) {
 575                 quota_error(dquot->dq_sb, "Can't read quota tree block %u",
 576                             blk);
 577                 goto out_buf;
 578         }
 579         ret = 0;
 580         blk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
 581         if (!blk)       /* No reference? */
 582                 goto out_buf;
 583         if (depth < info->dqi_qtree_depth - 1)
 584                 ret = find_tree_dqentry(info, dquot, blk, depth+1);
 585         else
 586                 ret = find_block_dqentry(info, dquot, blk);
 587 out_buf:
 588         kfree(buf);
 589         return ret;
 590 }
 591
 592 /* Find entry for given id in the tree - wrapper function */
 593 static inline loff_t find_dqentry(struct qtree_mem_dqinfo *info,
 594                                   struct dquot *dquot)
 595 {
 596         return find_tree_dqentry(info, dquot, QT_TREEOFF, 0);
 597 }
 598
 599 int qtree_read_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot)
 600 {
 601         int type = dquot->dq_id.type;
 602         struct super_block *sb = dquot->dq_sb;
 603         loff_t offset;
 604         char *ddquot;
 605         int ret = 0;
 606
 607 #ifdef __QUOTA_QT_PARANOIA
 608         /* Invalidated quota? */
 609         if (!sb_dqopt(dquot->dq_sb)->files[type]) {
 610                 quota_error(sb, "Quota invalidated while reading!");
 611                 return -EIO;
 612         }
 613 #endif
 614         /* Do we know offset of the dquot entry in the quota file? */
 615         if (!dquot->dq_off) {
 616                 offset = find_dqentry(info, dquot);
 617                 if (offset <= 0) {      /* Entry not present? */
 618                         if (offset < 0)
 619                                 quota_error(sb,"Can't read quota structure "
 620                                             "for id %u",
 621                                             from_kqid(&init_user_ns,
 622                                                       dquot->dq_id));
 623                         dquot->dq_off = 0;
 624                         set_bit(DQ_FAKE_B, &dquot->dq_flags);
 625                         memset(&dquot->dq_dqb, 0, sizeof(struct mem_dqblk));
 626                         ret = offset;
 627                         goto out;
 628                 }
 629                 dquot->dq_off = offset;
 630         }
 631         ddquot = getdqbuf(info->dqi_entry_size);
 632         if (!ddquot)
 633                 return -ENOMEM;
 634         ret = sb->s_op->quota_read(sb, type, ddquot, info->dqi_entry_size,
 635                                    dquot->dq_off);
 636         if (ret != info->dqi_entry_size) {
 637                 if (ret >= 0)
 638                         ret = -EIO;
 639                 quota_error(sb, "Error while reading quota structure for id %u",
 640                             from_kqid(&init_user_ns, dquot->dq_id));
 641                 set_bit(DQ_FAKE_B, &dquot->dq_flags);
 642                 memset(&dquot->dq_dqb, 0, sizeof(struct mem_dqblk));
 643                 kfree(ddquot);
 644                 goto out;
 645         }
 646         spin_lock(&dq_data_lock);
 647         info->dqi_ops->disk2mem_dqblk(dquot, ddquot);
 648         if (!dquot->dq_dqb.dqb_bhardlimit &&
 649             !dquot->dq_dqb.dqb_bsoftlimit &&
 650             !dquot->dq_dqb.dqb_ihardlimit &&
 651             !dquot->dq_dqb.dqb_isoftlimit)
 652                 set_bit(DQ_FAKE_B, &dquot->dq_flags);
 653         spin_unlock(&dq_data_lock);
 654         kfree(ddquot);
 655 out:
 656         dqstats_inc(DQST_READS);
 657         return ret;
 658 }
 659 EXPORT_SYMBOL(qtree_read_dquot);
 660
 661 /* Check whether dquot should not be deleted. We know we are
 662  * the only one operating on dquot (thanks to dq_lock) */
 663 int qtree_release_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot)
 664 {
 665         if (test_bit(DQ_FAKE_B, &dquot->dq_flags) &&
 666             !(dquot->dq_dqb.dqb_curinodes | dquot->dq_dqb.dqb_curspace))
 667                 return qtree_delete_dquot(info, dquot);
 668         return 0;
 669 }
 670 EXPORT_SYMBOL(qtree_release_dquot);