fs/nilfs2/cpfile.c

   1 /*
   2  * cpfile.c - NILFS checkpoint file.
   3  *
   4  * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * Written by Koji Sato.
  17  */
  18
  19 #include <linux/kernel.h>
  20 #include <linux/fs.h>
  21 #include <linux/string.h>
  22 #include <linux/buffer_head.h>
  23 #include <linux/errno.h>
  24 #include "mdt.h"
  25 #include "cpfile.h"
  26
  27
  28 static inline unsigned long
  29 nilfs_cpfile_checkpoints_per_block(const struct inode *cpfile)
  30 {
  31         return NILFS_MDT(cpfile)->mi_entries_per_block;
  32 }
  33
  34 /* block number from the beginning of the file */
  35 static unsigned long
  36 nilfs_cpfile_get_blkoff(const struct inode *cpfile, __u64 cno)
  37 {
  38         __u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
  39
  40         do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
  41         return (unsigned long)tcno;
  42 }
  43
  44 /* offset in block */
  45 static unsigned long
  46 nilfs_cpfile_get_offset(const struct inode *cpfile, __u64 cno)
  47 {
  48         __u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
  49
  50         return do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
  51 }
  52
  53 static __u64 nilfs_cpfile_first_checkpoint_in_block(const struct inode *cpfile,
  54                                                     unsigned long blkoff)
  55 {
  56         return (__u64)nilfs_cpfile_checkpoints_per_block(cpfile) * blkoff
  57                 + 1 - NILFS_MDT(cpfile)->mi_first_entry_offset;
  58 }
  59
  60 static unsigned long
  61 nilfs_cpfile_checkpoints_in_block(const struct inode *cpfile,
  62                                   __u64 curr,
  63                                   __u64 max)
  64 {
  65         return min_t(__u64,
  66                      nilfs_cpfile_checkpoints_per_block(cpfile) -
  67                      nilfs_cpfile_get_offset(cpfile, curr),
  68                      max - curr);
  69 }
  70
  71 static inline int nilfs_cpfile_is_in_first(const struct inode *cpfile,
  72                                            __u64 cno)
  73 {
  74         return nilfs_cpfile_get_blkoff(cpfile, cno) == 0;
  75 }
  76
  77 static unsigned int
  78 nilfs_cpfile_block_add_valid_checkpoints(const struct inode *cpfile,
  79                                          struct buffer_head *bh,
  80                                          void *kaddr,
  81                                          unsigned int n)
  82 {
  83         struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
  84         unsigned int count;
  85
  86         count = le32_to_cpu(cp->cp_checkpoints_count) + n;
  87         cp->cp_checkpoints_count = cpu_to_le32(count);
  88         return count;
  89 }
  90
  91 static unsigned int
  92 nilfs_cpfile_block_sub_valid_checkpoints(const struct inode *cpfile,
  93                                          struct buffer_head *bh,
  94                                          void *kaddr,
  95                                          unsigned int n)
  96 {
  97         struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
  98         unsigned int count;
  99
 100         WARN_ON(le32_to_cpu(cp->cp_checkpoints_count) < n);
 101         count = le32_to_cpu(cp->cp_checkpoints_count) - n;
 102         cp->cp_checkpoints_count = cpu_to_le32(count);
 103         return count;
 104 }
 105
 106 static inline struct nilfs_cpfile_header *
 107 nilfs_cpfile_block_get_header(const struct inode *cpfile,
 108                               struct buffer_head *bh,
 109                               void *kaddr)
 110 {
 111         return kaddr + bh_offset(bh);
 112 }
 113
 114 static struct nilfs_checkpoint *
 115 nilfs_cpfile_block_get_checkpoint(const struct inode *cpfile, __u64 cno,
 116                                   struct buffer_head *bh,
 117                                   void *kaddr)
 118 {
 119         return kaddr + bh_offset(bh) + nilfs_cpfile_get_offset(cpfile, cno) *
 120                 NILFS_MDT(cpfile)->mi_entry_size;
 121 }
 122
 123 static void nilfs_cpfile_block_init(struct inode *cpfile,
 124                                     struct buffer_head *bh,
 125                                     void *kaddr)
 126 {
 127         struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
 128         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 129         int n = nilfs_cpfile_checkpoints_per_block(cpfile);
 130
 131         while (n-- > 0) {
 132                 nilfs_checkpoint_set_invalid(cp);
 133                 cp = (void *)cp + cpsz;
 134         }
 135 }
 136
 137 static inline int nilfs_cpfile_get_header_block(struct inode *cpfile,
 138                                                 struct buffer_head **bhp)
 139 {
 140         return nilfs_mdt_get_block(cpfile, 0, 0, NULL, bhp);
 141 }
 142
 143 static inline int nilfs_cpfile_get_checkpoint_block(struct inode *cpfile,
 144                                                     __u64 cno,
 145                                                     int create,
 146                                                     struct buffer_head **bhp)
 147 {
 148         return nilfs_mdt_get_block(cpfile,
 149                                    nilfs_cpfile_get_blkoff(cpfile, cno),
 150                                    create, nilfs_cpfile_block_init, bhp);
 151 }
 152
 153 /**
 154  * nilfs_cpfile_find_checkpoint_block - find and get a buffer on cpfile
 155  * @cpfile: inode of cpfile
 156  * @start_cno: start checkpoint number (inclusive)
 157  * @end_cno: end checkpoint number (inclusive)
 158  * @cnop: place to store the next checkpoint number
 159  * @bhp: place to store a pointer to buffer_head struct
 160  *
 161  * Return Value: On success, it returns 0. On error, the following negative
 162  * error code is returned.
 163  *
 164  * %-ENOMEM - Insufficient memory available.
 165  *
 166  * %-EIO - I/O error
 167  *
 168  * %-ENOENT - no block exists in the range.
 169  */
 170 static int nilfs_cpfile_find_checkpoint_block(struct inode *cpfile,
 171                                               __u64 start_cno, __u64 end_cno,
 172                                               __u64 *cnop,
 173                                               struct buffer_head **bhp)
 174 {
 175         unsigned long start, end, blkoff;
 176         int ret;
 177
 178         if (unlikely(start_cno > end_cno))
 179                 return -ENOENT;
 180
 181         start = nilfs_cpfile_get_blkoff(cpfile, start_cno);
 182         end = nilfs_cpfile_get_blkoff(cpfile, end_cno);
 183
 184         ret = nilfs_mdt_find_block(cpfile, start, end, &blkoff, bhp);
 185         if (!ret)
 186                 *cnop = (blkoff == start) ? start_cno :
 187                         nilfs_cpfile_first_checkpoint_in_block(cpfile, blkoff);
 188         return ret;
 189 }
 190
 191 static inline int nilfs_cpfile_delete_checkpoint_block(struct inode *cpfile,
 192                                                        __u64 cno)
 193 {
 194         return nilfs_mdt_delete_block(cpfile,
 195                                       nilfs_cpfile_get_blkoff(cpfile, cno));
 196 }
 197
 198 /**
 199  * nilfs_cpfile_get_checkpoint - get a checkpoint
 200  * @cpfile: inode of checkpoint file
 201  * @cno: checkpoint number
 202  * @create: create flag
 203  * @cpp: pointer to a checkpoint
 204  * @bhp: pointer to a buffer head
 205  *
 206  * Description: nilfs_cpfile_get_checkpoint() acquires the checkpoint
 207  * specified by @cno. A new checkpoint will be created if @cno is the current
 208  * checkpoint number and @create is nonzero.
 209  *
 210  * Return Value: On success, 0 is returned, and the checkpoint and the
 211  * buffer head of the buffer on which the checkpoint is located are stored in
 212  * the place pointed by @cpp and @bhp, respectively. On error, one of the
 213  * following negative error codes is returned.
 214  *
 215  * %-EIO - I/O error.
 216  *
 217  * %-ENOMEM - Insufficient amount of memory available.
 218  *
 219  * %-ENOENT - No such checkpoint.
 220  *
 221  * %-EINVAL - invalid checkpoint.
 222  */
 223 int nilfs_cpfile_get_checkpoint(struct inode *cpfile,
 224                                 __u64 cno,
 225                                 int create,
 226                                 struct nilfs_checkpoint **cpp,
 227                                 struct buffer_head **bhp)
 228 {
 229         struct buffer_head *header_bh, *cp_bh;
 230         struct nilfs_cpfile_header *header;
 231         struct nilfs_checkpoint *cp;
 232         void *kaddr;
 233         int ret;
 234
 235         if (unlikely(cno < 1 || cno > nilfs_mdt_cno(cpfile) ||
 236                      (cno < nilfs_mdt_cno(cpfile) && create)))
 237                 return -EINVAL;
 238
 239         down_write(&NILFS_MDT(cpfile)->mi_sem);
 240
 241         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 242         if (ret < 0)
 243                 goto out_sem;
 244         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, create, &cp_bh);
 245         if (ret < 0)
 246                 goto out_header;
 247         kaddr = kmap(cp_bh->b_page);
 248         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 249         if (nilfs_checkpoint_invalid(cp)) {
 250                 if (!create) {
 251                         kunmap(cp_bh->b_page);
 252                         brelse(cp_bh);
 253                         ret = -ENOENT;
 254                         goto out_header;
 255                 }
 256                 /* a newly-created checkpoint */
 257                 nilfs_checkpoint_clear_invalid(cp);
 258                 if (!nilfs_cpfile_is_in_first(cpfile, cno))
 259                         nilfs_cpfile_block_add_valid_checkpoints(cpfile, cp_bh,
 260                                                                  kaddr, 1);
 261                 mark_buffer_dirty(cp_bh);
 262
 263                 kaddr = kmap_atomic(header_bh->b_page);
 264                 header = nilfs_cpfile_block_get_header(cpfile, header_bh,
 265                                                        kaddr);
 266                 le64_add_cpu(&header->ch_ncheckpoints, 1);
 267                 kunmap_atomic(kaddr);
 268                 mark_buffer_dirty(header_bh);
 269                 nilfs_mdt_mark_dirty(cpfile);
 270         }
 271
 272         if (cpp != NULL)
 273                 *cpp = cp;
 274         *bhp = cp_bh;
 275
 276  out_header:
 277         brelse(header_bh);
 278
 279  out_sem:
 280         up_write(&NILFS_MDT(cpfile)->mi_sem);
 281         return ret;
 282 }
 283
 284 /**
 285  * nilfs_cpfile_put_checkpoint - put a checkpoint
 286  * @cpfile: inode of checkpoint file
 287  * @cno: checkpoint number
 288  * @bh: buffer head
 289  *
 290  * Description: nilfs_cpfile_put_checkpoint() releases the checkpoint
 291  * specified by @cno. @bh must be the buffer head which has been returned by
 292  * a previous call to nilfs_cpfile_get_checkpoint() with @cno.
 293  */
 294 void nilfs_cpfile_put_checkpoint(struct inode *cpfile, __u64 cno,
 295                                  struct buffer_head *bh)
 296 {
 297         kunmap(bh->b_page);
 298         brelse(bh);
 299 }
 300
 301 /**
 302  * nilfs_cpfile_delete_checkpoints - delete checkpoints
 303  * @cpfile: inode of checkpoint file
 304  * @start: start checkpoint number
 305  * @end: end checkpoint numer
 306  *
 307  * Description: nilfs_cpfile_delete_checkpoints() deletes the checkpoints in
 308  * the period from @start to @end, excluding @end itself. The checkpoints
 309  * which have been already deleted are ignored.
 310  *
 311  * Return Value: On success, 0 is returned. On error, one of the following
 312  * negative error codes is returned.
 313  *
 314  * %-EIO - I/O error.
 315  *
 316  * %-ENOMEM - Insufficient amount of memory available.
 317  *
 318  * %-EINVAL - invalid checkpoints.
 319  */
 320 int nilfs_cpfile_delete_checkpoints(struct inode *cpfile,
 321                                     __u64 start,
 322                                     __u64 end)
 323 {
 324         struct buffer_head *header_bh, *cp_bh;
 325         struct nilfs_cpfile_header *header;
 326         struct nilfs_checkpoint *cp;
 327         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 328         __u64 cno;
 329         void *kaddr;
 330         unsigned long tnicps;
 331         int ret, ncps, nicps, nss, count, i;
 332
 333         if (unlikely(start == 0 || start > end)) {
 334                 nilfs_msg(cpfile->i_sb, KERN_ERR,
 335                           "cannot delete checkpoints: invalid range [%llu, %llu)",
 336                           (unsigned long long)start, (unsigned long long)end);
 337                 return -EINVAL;
 338         }
 339
 340         down_write(&NILFS_MDT(cpfile)->mi_sem);
 341
 342         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 343         if (ret < 0)
 344                 goto out_sem;
 345         tnicps = 0;
 346         nss = 0;
 347
 348         for (cno = start; cno < end; cno += ncps) {
 349                 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, end);
 350                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 351                 if (ret < 0) {
 352                         if (ret != -ENOENT)
 353                                 break;
 354                         /* skip hole */
 355                         ret = 0;
 356                         continue;
 357                 }
 358
 359                 kaddr = kmap_atomic(cp_bh->b_page);
 360                 cp = nilfs_cpfile_block_get_checkpoint(
 361                         cpfile, cno, cp_bh, kaddr);
 362                 nicps = 0;
 363                 for (i = 0; i < ncps; i++, cp = (void *)cp + cpsz) {
 364                         if (nilfs_checkpoint_snapshot(cp)) {
 365                                 nss++;
 366                         } else if (!nilfs_checkpoint_invalid(cp)) {
 367                                 nilfs_checkpoint_set_invalid(cp);
 368                                 nicps++;
 369                         }
 370                 }
 371                 if (nicps > 0) {
 372                         tnicps += nicps;
 373                         mark_buffer_dirty(cp_bh);
 374                         nilfs_mdt_mark_dirty(cpfile);
 375                         if (!nilfs_cpfile_is_in_first(cpfile, cno)) {
 376                                 count =
 377                                   nilfs_cpfile_block_sub_valid_checkpoints(
 378                                                 cpfile, cp_bh, kaddr, nicps);
 379                                 if (count == 0) {
 380                                         /* make hole */
 381                                         kunmap_atomic(kaddr);
 382                                         brelse(cp_bh);
 383                                         ret =
 384                                           nilfs_cpfile_delete_checkpoint_block(
 385                                                                    cpfile, cno);
 386                                         if (ret == 0)
 387                                                 continue;
 388                                         nilfs_msg(cpfile->i_sb, KERN_ERR,
 389                                                   "error %d deleting checkpoint block",
 390                                                   ret);
 391                                         break;
 392                                 }
 393                         }
 394                 }
 395
 396                 kunmap_atomic(kaddr);
 397                 brelse(cp_bh);
 398         }
 399
 400         if (tnicps > 0) {
 401                 kaddr = kmap_atomic(header_bh->b_page);
 402                 header = nilfs_cpfile_block_get_header(cpfile, header_bh,
 403                                                        kaddr);
 404                 le64_add_cpu(&header->ch_ncheckpoints, -(u64)tnicps);
 405                 mark_buffer_dirty(header_bh);
 406                 nilfs_mdt_mark_dirty(cpfile);
 407                 kunmap_atomic(kaddr);
 408         }
 409
 410         brelse(header_bh);
 411         if (nss > 0)
 412                 ret = -EBUSY;
 413
 414  out_sem:
 415         up_write(&NILFS_MDT(cpfile)->mi_sem);
 416         return ret;
 417 }
 418
 419 static void nilfs_cpfile_checkpoint_to_cpinfo(struct inode *cpfile,
 420                                               struct nilfs_checkpoint *cp,
 421                                               struct nilfs_cpinfo *ci)
 422 {
 423         ci->ci_flags = le32_to_cpu(cp->cp_flags);
 424         ci->ci_cno = le64_to_cpu(cp->cp_cno);
 425         ci->ci_create = le64_to_cpu(cp->cp_create);
 426         ci->ci_nblk_inc = le64_to_cpu(cp->cp_nblk_inc);
 427         ci->ci_inodes_count = le64_to_cpu(cp->cp_inodes_count);
 428         ci->ci_blocks_count = le64_to_cpu(cp->cp_blocks_count);
 429         ci->ci_next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
 430 }
 431
 432 static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
 433                                           void *buf, unsigned int cisz,
 434                                           size_t nci)
 435 {
 436         struct nilfs_checkpoint *cp;
 437         struct nilfs_cpinfo *ci = buf;
 438         struct buffer_head *bh;
 439         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 440         __u64 cur_cno = nilfs_mdt_cno(cpfile), cno = *cnop;
 441         void *kaddr;
 442         int n, ret;
 443         int ncps, i;
 444
 445         if (cno == 0)
 446                 return -ENOENT; /* checkpoint number 0 is invalid */
 447         down_read(&NILFS_MDT(cpfile)->mi_sem);
 448
 449         for (n = 0; n < nci; cno += ncps) {
 450                 ret = nilfs_cpfile_find_checkpoint_block(
 451                         cpfile, cno, cur_cno - 1, &cno, &bh);
 452                 if (ret < 0) {
 453                         if (likely(ret == -ENOENT))
 454                                 break;
 455                         goto out;
 456                 }
 457                 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
 458
 459                 kaddr = kmap_atomic(bh->b_page);
 460                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 461                 for (i = 0; i < ncps && n < nci; i++, cp = (void *)cp + cpsz) {
 462                         if (!nilfs_checkpoint_invalid(cp)) {
 463                                 nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp,
 464                                                                   ci);
 465                                 ci = (void *)ci + cisz;
 466                                 n++;
 467                         }
 468                 }
 469                 kunmap_atomic(kaddr);
 470                 brelse(bh);
 471         }
 472
 473         ret = n;
 474         if (n > 0) {
 475                 ci = (void *)ci - cisz;
 476                 *cnop = ci->ci_cno + 1;
 477         }
 478
 479  out:
 480         up_read(&NILFS_MDT(cpfile)->mi_sem);
 481         return ret;
 482 }
 483
 484 static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
 485                                           void *buf, unsigned int cisz,
 486                                           size_t nci)
 487 {
 488         struct buffer_head *bh;
 489         struct nilfs_cpfile_header *header;
 490         struct nilfs_checkpoint *cp;
 491         struct nilfs_cpinfo *ci = buf;
 492         __u64 curr = *cnop, next;
 493         unsigned long curr_blkoff, next_blkoff;
 494         void *kaddr;
 495         int n = 0, ret;
 496
 497         down_read(&NILFS_MDT(cpfile)->mi_sem);
 498
 499         if (curr == 0) {
 500                 ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 501                 if (ret < 0)
 502                         goto out;
 503                 kaddr = kmap_atomic(bh->b_page);
 504                 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 505                 curr = le64_to_cpu(header->ch_snapshot_list.ssl_next);
 506                 kunmap_atomic(kaddr);
 507                 brelse(bh);
 508                 if (curr == 0) {
 509                         ret = 0;
 510                         goto out;
 511                 }
 512         } else if (unlikely(curr == ~(__u64)0)) {
 513                 ret = 0;
 514                 goto out;
 515         }
 516
 517         curr_blkoff = nilfs_cpfile_get_blkoff(cpfile, curr);
 518         ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr, 0, &bh);
 519         if (unlikely(ret < 0)) {
 520                 if (ret == -ENOENT)
 521                         ret = 0; /* No snapshots (started from a hole block) */
 522                 goto out;
 523         }
 524         kaddr = kmap_atomic(bh->b_page);
 525         while (n < nci) {
 526                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, curr, bh, kaddr);
 527                 curr = ~(__u64)0; /* Terminator */
 528                 if (unlikely(nilfs_checkpoint_invalid(cp) ||
 529                              !nilfs_checkpoint_snapshot(cp)))
 530                         break;
 531                 nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp, ci);
 532                 ci = (void *)ci + cisz;
 533                 n++;
 534                 next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
 535                 if (next == 0)
 536                         break; /* reach end of the snapshot list */
 537
 538                 next_blkoff = nilfs_cpfile_get_blkoff(cpfile, next);
 539                 if (curr_blkoff != next_blkoff) {
 540                         kunmap_atomic(kaddr);
 541                         brelse(bh);
 542                         ret = nilfs_cpfile_get_checkpoint_block(cpfile, next,
 543                                                                 0, &bh);
 544                         if (unlikely(ret < 0)) {
 545                                 WARN_ON(ret == -ENOENT);
 546                                 goto out;
 547                         }
 548                         kaddr = kmap_atomic(bh->b_page);
 549                 }
 550                 curr = next;
 551                 curr_blkoff = next_blkoff;
 552         }
 553         kunmap_atomic(kaddr);
 554         brelse(bh);
 555         *cnop = curr;
 556         ret = n;
 557
 558  out:
 559         up_read(&NILFS_MDT(cpfile)->mi_sem);
 560         return ret;
 561 }
 562
 563 /**
 564  * nilfs_cpfile_get_cpinfo -
 565  * @cpfile:
 566  * @cno:
 567  * @ci:
 568  * @nci:
 569  */
 570
 571 ssize_t nilfs_cpfile_get_cpinfo(struct inode *cpfile, __u64 *cnop, int mode,
 572                                 void *buf, unsigned int cisz, size_t nci)
 573 {
 574         switch (mode) {
 575         case NILFS_CHECKPOINT:
 576                 return nilfs_cpfile_do_get_cpinfo(cpfile, cnop, buf, cisz, nci);
 577         case NILFS_SNAPSHOT:
 578                 return nilfs_cpfile_do_get_ssinfo(cpfile, cnop, buf, cisz, nci);
 579         default:
 580                 return -EINVAL;
 581         }
 582 }
 583
 584 /**
 585  * nilfs_cpfile_delete_checkpoint -
 586  * @cpfile:
 587  * @cno:
 588  */
 589 int nilfs_cpfile_delete_checkpoint(struct inode *cpfile, __u64 cno)
 590 {
 591         struct nilfs_cpinfo ci;
 592         __u64 tcno = cno;
 593         ssize_t nci;
 594
 595         nci = nilfs_cpfile_do_get_cpinfo(cpfile, &tcno, &ci, sizeof(ci), 1);
 596         if (nci < 0)
 597                 return nci;
 598         else if (nci == 0 || ci.ci_cno != cno)
 599                 return -ENOENT;
 600         else if (nilfs_cpinfo_snapshot(&ci))
 601                 return -EBUSY;
 602
 603         return nilfs_cpfile_delete_checkpoints(cpfile, cno, cno + 1);
 604 }
 605
 606 static struct nilfs_snapshot_list *
 607 nilfs_cpfile_block_get_snapshot_list(const struct inode *cpfile,
 608                                      __u64 cno,
 609                                      struct buffer_head *bh,
 610                                      void *kaddr)
 611 {
 612         struct nilfs_cpfile_header *header;
 613         struct nilfs_checkpoint *cp;
 614         struct nilfs_snapshot_list *list;
 615
 616         if (cno != 0) {
 617                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 618                 list = &cp->cp_snapshot_list;
 619         } else {
 620                 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 621                 list = &header->ch_snapshot_list;
 622         }
 623         return list;
 624 }
 625
 626 static int nilfs_cpfile_set_snapshot(struct inode *cpfile, __u64 cno)
 627 {
 628         struct buffer_head *header_bh, *curr_bh, *prev_bh, *cp_bh;
 629         struct nilfs_cpfile_header *header;
 630         struct nilfs_checkpoint *cp;
 631         struct nilfs_snapshot_list *list;
 632         __u64 curr, prev;
 633         unsigned long curr_blkoff, prev_blkoff;
 634         void *kaddr;
 635         int ret;
 636
 637         if (cno == 0)
 638                 return -ENOENT; /* checkpoint number 0 is invalid */
 639         down_write(&NILFS_MDT(cpfile)->mi_sem);
 640
 641         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 642         if (ret < 0)
 643                 goto out_sem;
 644         kaddr = kmap_atomic(cp_bh->b_page);
 645         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 646         if (nilfs_checkpoint_invalid(cp)) {
 647                 ret = -ENOENT;
 648                 kunmap_atomic(kaddr);
 649                 goto out_cp;
 650         }
 651         if (nilfs_checkpoint_snapshot(cp)) {
 652                 ret = 0;
 653                 kunmap_atomic(kaddr);
 654                 goto out_cp;
 655         }
 656         kunmap_atomic(kaddr);
 657
 658         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 659         if (ret < 0)
 660                 goto out_cp;
 661         kaddr = kmap_atomic(header_bh->b_page);
 662         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 663         list = &header->ch_snapshot_list;
 664         curr_bh = header_bh;
 665         get_bh(curr_bh);
 666         curr = 0;
 667         curr_blkoff = 0;
 668         prev = le64_to_cpu(list->ssl_prev);
 669         while (prev > cno) {
 670                 prev_blkoff = nilfs_cpfile_get_blkoff(cpfile, prev);
 671                 curr = prev;
 672                 if (curr_blkoff != prev_blkoff) {
 673                         kunmap_atomic(kaddr);
 674                         brelse(curr_bh);
 675                         ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr,
 676                                                                 0, &curr_bh);
 677                         if (ret < 0)
 678                                 goto out_header;
 679                         kaddr = kmap_atomic(curr_bh->b_page);
 680                 }
 681                 curr_blkoff = prev_blkoff;
 682                 cp = nilfs_cpfile_block_get_checkpoint(
 683                         cpfile, curr, curr_bh, kaddr);
 684                 list = &cp->cp_snapshot_list;
 685                 prev = le64_to_cpu(list->ssl_prev);
 686         }
 687         kunmap_atomic(kaddr);
 688
 689         if (prev != 0) {
 690                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 691                                                         &prev_bh);
 692                 if (ret < 0)
 693                         goto out_curr;
 694         } else {
 695                 prev_bh = header_bh;
 696                 get_bh(prev_bh);
 697         }
 698
 699         kaddr = kmap_atomic(curr_bh->b_page);
 700         list = nilfs_cpfile_block_get_snapshot_list(
 701                 cpfile, curr, curr_bh, kaddr);
 702         list->ssl_prev = cpu_to_le64(cno);
 703         kunmap_atomic(kaddr);
 704
 705         kaddr = kmap_atomic(cp_bh->b_page);
 706         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 707         cp->cp_snapshot_list.ssl_next = cpu_to_le64(curr);
 708         cp->cp_snapshot_list.ssl_prev = cpu_to_le64(prev);
 709         nilfs_checkpoint_set_snapshot(cp);
 710         kunmap_atomic(kaddr);
 711
 712         kaddr = kmap_atomic(prev_bh->b_page);
 713         list = nilfs_cpfile_block_get_snapshot_list(
 714                 cpfile, prev, prev_bh, kaddr);
 715         list->ssl_next = cpu_to_le64(cno);
 716         kunmap_atomic(kaddr);
 717
 718         kaddr = kmap_atomic(header_bh->b_page);
 719         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 720         le64_add_cpu(&header->ch_nsnapshots, 1);
 721         kunmap_atomic(kaddr);
 722
 723         mark_buffer_dirty(prev_bh);
 724         mark_buffer_dirty(curr_bh);
 725         mark_buffer_dirty(cp_bh);
 726         mark_buffer_dirty(header_bh);
 727         nilfs_mdt_mark_dirty(cpfile);
 728
 729         brelse(prev_bh);
 730
 731  out_curr:
 732         brelse(curr_bh);
 733
 734  out_header:
 735         brelse(header_bh);
 736
 737  out_cp:
 738         brelse(cp_bh);
 739
 740  out_sem:
 741         up_write(&NILFS_MDT(cpfile)->mi_sem);
 742         return ret;
 743 }
 744
 745 static int nilfs_cpfile_clear_snapshot(struct inode *cpfile, __u64 cno)
 746 {
 747         struct buffer_head *header_bh, *next_bh, *prev_bh, *cp_bh;
 748         struct nilfs_cpfile_header *header;
 749         struct nilfs_checkpoint *cp;
 750         struct nilfs_snapshot_list *list;
 751         __u64 next, prev;
 752         void *kaddr;
 753         int ret;
 754
 755         if (cno == 0)
 756                 return -ENOENT; /* checkpoint number 0 is invalid */
 757         down_write(&NILFS_MDT(cpfile)->mi_sem);
 758
 759         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 760         if (ret < 0)
 761                 goto out_sem;
 762         kaddr = kmap_atomic(cp_bh->b_page);
 763         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 764         if (nilfs_checkpoint_invalid(cp)) {
 765                 ret = -ENOENT;
 766                 kunmap_atomic(kaddr);
 767                 goto out_cp;
 768         }
 769         if (!nilfs_checkpoint_snapshot(cp)) {
 770                 ret = 0;
 771                 kunmap_atomic(kaddr);
 772                 goto out_cp;
 773         }
 774
 775         list = &cp->cp_snapshot_list;
 776         next = le64_to_cpu(list->ssl_next);
 777         prev = le64_to_cpu(list->ssl_prev);
 778         kunmap_atomic(kaddr);
 779
 780         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 781         if (ret < 0)
 782                 goto out_cp;
 783         if (next != 0) {
 784                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, next, 0,
 785                                                         &next_bh);
 786                 if (ret < 0)
 787                         goto out_header;
 788         } else {
 789                 next_bh = header_bh;
 790                 get_bh(next_bh);
 791         }
 792         if (prev != 0) {
 793                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 794                                                         &prev_bh);
 795                 if (ret < 0)
 796                         goto out_next;
 797         } else {
 798                 prev_bh = header_bh;
 799                 get_bh(prev_bh);
 800         }
 801
 802         kaddr = kmap_atomic(next_bh->b_page);
 803         list = nilfs_cpfile_block_get_snapshot_list(
 804                 cpfile, next, next_bh, kaddr);
 805         list->ssl_prev = cpu_to_le64(prev);
 806         kunmap_atomic(kaddr);
 807
 808         kaddr = kmap_atomic(prev_bh->b_page);
 809         list = nilfs_cpfile_block_get_snapshot_list(
 810                 cpfile, prev, prev_bh, kaddr);
 811         list->ssl_next = cpu_to_le64(next);
 812         kunmap_atomic(kaddr);
 813
 814         kaddr = kmap_atomic(cp_bh->b_page);
 815         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 816         cp->cp_snapshot_list.ssl_next = cpu_to_le64(0);
 817         cp->cp_snapshot_list.ssl_prev = cpu_to_le64(0);
 818         nilfs_checkpoint_clear_snapshot(cp);
 819         kunmap_atomic(kaddr);
 820
 821         kaddr = kmap_atomic(header_bh->b_page);
 822         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 823         le64_add_cpu(&header->ch_nsnapshots, -1);
 824         kunmap_atomic(kaddr);
 825
 826         mark_buffer_dirty(next_bh);
 827         mark_buffer_dirty(prev_bh);
 828         mark_buffer_dirty(cp_bh);
 829         mark_buffer_dirty(header_bh);
 830         nilfs_mdt_mark_dirty(cpfile);
 831
 832         brelse(prev_bh);
 833
 834  out_next:
 835         brelse(next_bh);
 836
 837  out_header:
 838         brelse(header_bh);
 839
 840  out_cp:
 841         brelse(cp_bh);
 842
 843  out_sem:
 844         up_write(&NILFS_MDT(cpfile)->mi_sem);
 845         return ret;
 846 }
 847
 848 /**
 849  * nilfs_cpfile_is_snapshot -
 850  * @cpfile: inode of checkpoint file
 851  * @cno: checkpoint number
 852  *
 853  * Description:
 854  *
 855  * Return Value: On success, 1 is returned if the checkpoint specified by
 856  * @cno is a snapshot, or 0 if not. On error, one of the following negative
 857  * error codes is returned.
 858  *
 859  * %-EIO - I/O error.
 860  *
 861  * %-ENOMEM - Insufficient amount of memory available.
 862  *
 863  * %-ENOENT - No such checkpoint.
 864  */
 865 int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
 866 {
 867         struct buffer_head *bh;
 868         struct nilfs_checkpoint *cp;
 869         void *kaddr;
 870         int ret;
 871
 872         /*
 873          * CP number is invalid if it's zero or larger than the
 874          * largest existing one.
 875          */
 876         if (cno == 0 || cno >= nilfs_mdt_cno(cpfile))
 877                 return -ENOENT;
 878         down_read(&NILFS_MDT(cpfile)->mi_sem);
 879
 880         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
 881         if (ret < 0)
 882                 goto out;
 883         kaddr = kmap_atomic(bh->b_page);
 884         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 885         if (nilfs_checkpoint_invalid(cp))
 886                 ret = -ENOENT;
 887         else
 888                 ret = nilfs_checkpoint_snapshot(cp);
 889         kunmap_atomic(kaddr);
 890         brelse(bh);
 891
 892  out:
 893         up_read(&NILFS_MDT(cpfile)->mi_sem);
 894         return ret;
 895 }
 896
 897 /**
 898  * nilfs_cpfile_change_cpmode - change checkpoint mode
 899  * @cpfile: inode of checkpoint file
 900  * @cno: checkpoint number
 901  * @status: mode of checkpoint
 902  *
 903  * Description: nilfs_change_cpmode() changes the mode of the checkpoint
 904  * specified by @cno. The mode @mode is NILFS_CHECKPOINT or NILFS_SNAPSHOT.
 905  *
 906  * Return Value: On success, 0 is returned. On error, one of the following
 907  * negative error codes is returned.
 908  *
 909  * %-EIO - I/O error.
 910  *
 911  * %-ENOMEM - Insufficient amount of memory available.
 912  *
 913  * %-ENOENT - No such checkpoint.
 914  */
 915 int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
 916 {
 917         int ret;
 918
 919         switch (mode) {
 920         case NILFS_CHECKPOINT:
 921                 if (nilfs_checkpoint_is_mounted(cpfile->i_sb, cno))
 922                         /*
 923                          * Current implementation does not have to protect
 924                          * plain read-only mounts since they are exclusive
 925                          * with a read/write mount and are protected from the
 926                          * cleaner.
 927                          */
 928                         ret = -EBUSY;
 929                 else
 930                         ret = nilfs_cpfile_clear_snapshot(cpfile, cno);
 931                 return ret;
 932         case NILFS_SNAPSHOT:
 933                 return nilfs_cpfile_set_snapshot(cpfile, cno);
 934         default:
 935                 return -EINVAL;
 936         }
 937 }
 938
 939 /**
 940  * nilfs_cpfile_get_stat - get checkpoint statistics
 941  * @cpfile: inode of checkpoint file
 942  * @stat: pointer to a structure of checkpoint statistics
 943  *
 944  * Description: nilfs_cpfile_get_stat() returns information about checkpoints.
 945  *
 946  * Return Value: On success, 0 is returned, and checkpoints information is
 947  * stored in the place pointed by @stat. On error, one of the following
 948  * negative error codes is returned.
 949  *
 950  * %-EIO - I/O error.
 951  *
 952  * %-ENOMEM - Insufficient amount of memory available.
 953  */
 954 int nilfs_cpfile_get_stat(struct inode *cpfile, struct nilfs_cpstat *cpstat)
 955 {
 956         struct buffer_head *bh;
 957         struct nilfs_cpfile_header *header;
 958         void *kaddr;
 959         int ret;
 960
 961         down_read(&NILFS_MDT(cpfile)->mi_sem);
 962
 963         ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 964         if (ret < 0)
 965                 goto out_sem;
 966         kaddr = kmap_atomic(bh->b_page);
 967         header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 968         cpstat->cs_cno = nilfs_mdt_cno(cpfile);
 969         cpstat->cs_ncps = le64_to_cpu(header->ch_ncheckpoints);
 970         cpstat->cs_nsss = le64_to_cpu(header->ch_nsnapshots);
 971         kunmap_atomic(kaddr);
 972         brelse(bh);
 973
 974  out_sem:
 975         up_read(&NILFS_MDT(cpfile)->mi_sem);
 976         return ret;
 977 }
 978
 979 /**
 980  * nilfs_cpfile_read - read or get cpfile inode
 981  * @sb: super block instance
 982  * @cpsize: size of a checkpoint entry
 983  * @raw_inode: on-disk cpfile inode
 984  * @inodep: buffer to store the inode
 985  */
 986 int nilfs_cpfile_read(struct super_block *sb, size_t cpsize,
 987                       struct nilfs_inode *raw_inode, struct inode **inodep)
 988 {
 989         struct inode *cpfile;
 990         int err;
 991
 992         if (cpsize > sb->s_blocksize) {
 993                 nilfs_msg(sb, KERN_ERR,
 994                           "too large checkpoint size: %zu bytes", cpsize);
 995                 return -EINVAL;
 996         } else if (cpsize < NILFS_MIN_CHECKPOINT_SIZE) {
 997                 nilfs_msg(sb, KERN_ERR,
 998                           "too small checkpoint size: %zu bytes", cpsize);
 999                 return -EINVAL;
1000         }
1001
1002         cpfile = nilfs_iget_locked(sb, NULL, NILFS_CPFILE_INO);
1003         if (unlikely(!cpfile))
1004                 return -ENOMEM;
1005         if (!(cpfile->i_state & I_NEW))
1006                 goto out;
1007
1008         err = nilfs_mdt_init(cpfile, NILFS_MDT_GFP, 0);
1009         if (err)
1010                 goto failed;
1011
1012         nilfs_mdt_set_entry_size(cpfile, cpsize,
1013                                  sizeof(struct nilfs_cpfile_header));
1014
1015         err = nilfs_read_inode_common(cpfile, raw_inode);
1016         if (err)
1017                 goto failed;
1018
1019         unlock_new_inode(cpfile);
1020  out:
1021         *inodep = cpfile;
1022         return 0;
1023  failed:
1024         iget_failed(cpfile);
1025         return err;
1026 }