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