fs/nilfs2/cpfile.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * cpfile.c - NILFS checkpoint file.
   4  *
   5  * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
   6  *
   7  * Written by Koji Sato.
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/fs.h>
  12 #include <linux/string.h>
  13 #include <linux/buffer_head.h>
  14 #include <linux/errno.h>
  15 #include "mdt.h"
  16 #include "cpfile.h"
  17
  18
  19 static inline unsigned long
  20 nilfs_cpfile_checkpoints_per_block(const struct inode *cpfile)
  21 {
  22         return NILFS_MDT(cpfile)->mi_entries_per_block;
  23 }
  24
  25 /* block number from the beginning of the file */
  26 static unsigned long
  27 nilfs_cpfile_get_blkoff(const struct inode *cpfile, __u64 cno)
  28 {
  29         __u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
  30
  31         do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
  32         return (unsigned long)tcno;
  33 }
  34
  35 /* offset in block */
  36 static unsigned long
  37 nilfs_cpfile_get_offset(const struct inode *cpfile, __u64 cno)
  38 {
  39         __u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
  40
  41         return do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
  42 }
  43
  44 static __u64 nilfs_cpfile_first_checkpoint_in_block(const struct inode *cpfile,
  45                                                     unsigned long blkoff)
  46 {
  47         return (__u64)nilfs_cpfile_checkpoints_per_block(cpfile) * blkoff
  48                 + 1 - NILFS_MDT(cpfile)->mi_first_entry_offset;
  49 }
  50
  51 static unsigned long
  52 nilfs_cpfile_checkpoints_in_block(const struct inode *cpfile,
  53                                   __u64 curr,
  54                                   __u64 max)
  55 {
  56         return min_t(__u64,
  57                      nilfs_cpfile_checkpoints_per_block(cpfile) -
  58                      nilfs_cpfile_get_offset(cpfile, curr),
  59                      max - curr);
  60 }
  61
  62 static inline int nilfs_cpfile_is_in_first(const struct inode *cpfile,
  63                                            __u64 cno)
  64 {
  65         return nilfs_cpfile_get_blkoff(cpfile, cno) == 0;
  66 }
  67
  68 static unsigned int
  69 nilfs_cpfile_block_add_valid_checkpoints(const struct inode *cpfile,
  70                                          struct buffer_head *bh,
  71                                          void *kaddr,
  72                                          unsigned int n)
  73 {
  74         struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
  75         unsigned int count;
  76
  77         count = le32_to_cpu(cp->cp_checkpoints_count) + n;
  78         cp->cp_checkpoints_count = cpu_to_le32(count);
  79         return count;
  80 }
  81
  82 static unsigned int
  83 nilfs_cpfile_block_sub_valid_checkpoints(const struct inode *cpfile,
  84                                          struct buffer_head *bh,
  85                                          void *kaddr,
  86                                          unsigned int n)
  87 {
  88         struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
  89         unsigned int count;
  90
  91         WARN_ON(le32_to_cpu(cp->cp_checkpoints_count) < n);
  92         count = le32_to_cpu(cp->cp_checkpoints_count) - n;
  93         cp->cp_checkpoints_count = cpu_to_le32(count);
  94         return count;
  95 }
  96
  97 static inline struct nilfs_cpfile_header *
  98 nilfs_cpfile_block_get_header(const struct inode *cpfile,
  99                               struct buffer_head *bh,
 100                               void *kaddr)
 101 {
 102         return kaddr + bh_offset(bh);
 103 }
 104
 105 static struct nilfs_checkpoint *
 106 nilfs_cpfile_block_get_checkpoint(const struct inode *cpfile, __u64 cno,
 107                                   struct buffer_head *bh,
 108                                   void *kaddr)
 109 {
 110         return kaddr + bh_offset(bh) + nilfs_cpfile_get_offset(cpfile, cno) *
 111                 NILFS_MDT(cpfile)->mi_entry_size;
 112 }
 113
 114 static void nilfs_cpfile_block_init(struct inode *cpfile,
 115                                     struct buffer_head *bh,
 116                                     void *kaddr)
 117 {
 118         struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
 119         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 120         int n = nilfs_cpfile_checkpoints_per_block(cpfile);
 121
 122         while (n-- > 0) {
 123                 nilfs_checkpoint_set_invalid(cp);
 124                 cp = (void *)cp + cpsz;
 125         }
 126 }
 127
 128 static inline int nilfs_cpfile_get_header_block(struct inode *cpfile,
 129                                                 struct buffer_head **bhp)
 130 {
 131         return nilfs_mdt_get_block(cpfile, 0, 0, NULL, bhp);
 132 }
 133
 134 static inline int nilfs_cpfile_get_checkpoint_block(struct inode *cpfile,
 135                                                     __u64 cno,
 136                                                     int create,
 137                                                     struct buffer_head **bhp)
 138 {
 139         return nilfs_mdt_get_block(cpfile,
 140                                    nilfs_cpfile_get_blkoff(cpfile, cno),
 141                                    create, nilfs_cpfile_block_init, bhp);
 142 }
 143
 144 /**
 145  * nilfs_cpfile_find_checkpoint_block - find and get a buffer on cpfile
 146  * @cpfile: inode of cpfile
 147  * @start_cno: start checkpoint number (inclusive)
 148  * @end_cno: end checkpoint number (inclusive)
 149  * @cnop: place to store the next checkpoint number
 150  * @bhp: place to store a pointer to buffer_head struct
 151  *
 152  * Return Value: On success, it returns 0. On error, the following negative
 153  * error code is returned.
 154  *
 155  * %-ENOMEM - Insufficient memory available.
 156  *
 157  * %-EIO - I/O error
 158  *
 159  * %-ENOENT - no block exists in the range.
 160  */
 161 static int nilfs_cpfile_find_checkpoint_block(struct inode *cpfile,
 162                                               __u64 start_cno, __u64 end_cno,
 163                                               __u64 *cnop,
 164                                               struct buffer_head **bhp)
 165 {
 166         unsigned long start, end, blkoff;
 167         int ret;
 168
 169         if (unlikely(start_cno > end_cno))
 170                 return -ENOENT;
 171
 172         start = nilfs_cpfile_get_blkoff(cpfile, start_cno);
 173         end = nilfs_cpfile_get_blkoff(cpfile, end_cno);
 174
 175         ret = nilfs_mdt_find_block(cpfile, start, end, &blkoff, bhp);
 176         if (!ret)
 177                 *cnop = (blkoff == start) ? start_cno :
 178                         nilfs_cpfile_first_checkpoint_in_block(cpfile, blkoff);
 179         return ret;
 180 }
 181
 182 static inline int nilfs_cpfile_delete_checkpoint_block(struct inode *cpfile,
 183                                                        __u64 cno)
 184 {
 185         return nilfs_mdt_delete_block(cpfile,
 186                                       nilfs_cpfile_get_blkoff(cpfile, cno));
 187 }
 188
 189 /**
 190  * nilfs_cpfile_get_checkpoint - get a checkpoint
 191  * @cpfile: inode of checkpoint file
 192  * @cno: checkpoint number
 193  * @create: create flag
 194  * @cpp: pointer to a checkpoint
 195  * @bhp: pointer to a buffer head
 196  *
 197  * Description: nilfs_cpfile_get_checkpoint() acquires the checkpoint
 198  * specified by @cno. A new checkpoint will be created if @cno is the current
 199  * checkpoint number and @create is nonzero.
 200  *
 201  * Return Value: On success, 0 is returned, and the checkpoint and the
 202  * buffer head of the buffer on which the checkpoint is located are stored in
 203  * the place pointed by @cpp and @bhp, respectively. On error, one of the
 204  * following negative error codes is returned.
 205  *
 206  * %-EIO - I/O error.
 207  *
 208  * %-ENOMEM - Insufficient amount of memory available.
 209  *
 210  * %-ENOENT - No such checkpoint.
 211  *
 212  * %-EINVAL - invalid checkpoint.
 213  */
 214 int nilfs_cpfile_get_checkpoint(struct inode *cpfile,
 215                                 __u64 cno,
 216                                 int create,
 217                                 struct nilfs_checkpoint **cpp,
 218                                 struct buffer_head **bhp)
 219 {
 220         struct buffer_head *header_bh, *cp_bh;
 221         struct nilfs_cpfile_header *header;
 222         struct nilfs_checkpoint *cp;
 223         void *kaddr;
 224         int ret;
 225
 226         if (unlikely(cno < 1 || cno > nilfs_mdt_cno(cpfile) ||
 227                      (cno < nilfs_mdt_cno(cpfile) && create)))
 228                 return -EINVAL;
 229
 230         down_write(&NILFS_MDT(cpfile)->mi_sem);
 231
 232         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 233         if (ret < 0)
 234                 goto out_sem;
 235         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, create, &cp_bh);
 236         if (ret < 0)
 237                 goto out_header;
 238         kaddr = kmap(cp_bh->b_page);
 239         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 240         if (nilfs_checkpoint_invalid(cp)) {
 241                 if (!create) {
 242                         kunmap(cp_bh->b_page);
 243                         brelse(cp_bh);
 244                         ret = -ENOENT;
 245                         goto out_header;
 246                 }
 247                 /* a newly-created checkpoint */
 248                 nilfs_checkpoint_clear_invalid(cp);
 249                 if (!nilfs_cpfile_is_in_first(cpfile, cno))
 250                         nilfs_cpfile_block_add_valid_checkpoints(cpfile, cp_bh,
 251                                                                  kaddr, 1);
 252                 mark_buffer_dirty(cp_bh);
 253
 254                 kaddr = kmap_atomic(header_bh->b_page);
 255                 header = nilfs_cpfile_block_get_header(cpfile, header_bh,
 256                                                        kaddr);
 257                 le64_add_cpu(&header->ch_ncheckpoints, 1);
 258                 kunmap_atomic(kaddr);
 259                 mark_buffer_dirty(header_bh);
 260                 nilfs_mdt_mark_dirty(cpfile);
 261         }
 262
 263         if (cpp != NULL)
 264                 *cpp = cp;
 265         *bhp = cp_bh;
 266
 267  out_header:
 268         brelse(header_bh);
 269
 270  out_sem:
 271         up_write(&NILFS_MDT(cpfile)->mi_sem);
 272         return ret;
 273 }
 274
 275 /**
 276  * nilfs_cpfile_put_checkpoint - put a checkpoint
 277  * @cpfile: inode of checkpoint file
 278  * @cno: checkpoint number
 279  * @bh: buffer head
 280  *
 281  * Description: nilfs_cpfile_put_checkpoint() releases the checkpoint
 282  * specified by @cno. @bh must be the buffer head which has been returned by
 283  * a previous call to nilfs_cpfile_get_checkpoint() with @cno.
 284  */
 285 void nilfs_cpfile_put_checkpoint(struct inode *cpfile, __u64 cno,
 286                                  struct buffer_head *bh)
 287 {
 288         kunmap(bh->b_page);
 289         brelse(bh);
 290 }
 291
 292 /**
 293  * nilfs_cpfile_delete_checkpoints - delete checkpoints
 294  * @cpfile: inode of checkpoint file
 295  * @start: start checkpoint number
 296  * @end: end checkpoint numer
 297  *
 298  * Description: nilfs_cpfile_delete_checkpoints() deletes the checkpoints in
 299  * the period from @start to @end, excluding @end itself. The checkpoints
 300  * which have been already deleted are ignored.
 301  *
 302  * Return Value: On success, 0 is returned. On error, one of the following
 303  * negative error codes is returned.
 304  *
 305  * %-EIO - I/O error.
 306  *
 307  * %-ENOMEM - Insufficient amount of memory available.
 308  *
 309  * %-EINVAL - invalid checkpoints.
 310  */
 311 int nilfs_cpfile_delete_checkpoints(struct inode *cpfile,
 312                                     __u64 start,
 313                                     __u64 end)
 314 {
 315         struct buffer_head *header_bh, *cp_bh;
 316         struct nilfs_cpfile_header *header;
 317         struct nilfs_checkpoint *cp;
 318         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 319         __u64 cno;
 320         void *kaddr;
 321         unsigned long tnicps;
 322         int ret, ncps, nicps, nss, count, i;
 323
 324         if (unlikely(start == 0 || start > end)) {
 325                 nilfs_msg(cpfile->i_sb, KERN_ERR,
 326                           "cannot delete checkpoints: invalid range [%llu, %llu)",
 327                           (unsigned long long)start, (unsigned long long)end);
 328                 return -EINVAL;
 329         }
 330
 331         down_write(&NILFS_MDT(cpfile)->mi_sem);
 332
 333         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 334         if (ret < 0)
 335                 goto out_sem;
 336         tnicps = 0;
 337         nss = 0;
 338
 339         for (cno = start; cno < end; cno += ncps) {
 340                 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, end);
 341                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 342                 if (ret < 0) {
 343                         if (ret != -ENOENT)
 344                                 break;
 345                         /* skip hole */
 346                         ret = 0;
 347                         continue;
 348                 }
 349
 350                 kaddr = kmap_atomic(cp_bh->b_page);
 351                 cp = nilfs_cpfile_block_get_checkpoint(
 352                         cpfile, cno, cp_bh, kaddr);
 353                 nicps = 0;
 354                 for (i = 0; i < ncps; i++, cp = (void *)cp + cpsz) {
 355                         if (nilfs_checkpoint_snapshot(cp)) {
 356                                 nss++;
 357                         } else if (!nilfs_checkpoint_invalid(cp)) {
 358                                 nilfs_checkpoint_set_invalid(cp);
 359                                 nicps++;
 360                         }
 361                 }
 362                 if (nicps > 0) {
 363                         tnicps += nicps;
 364                         mark_buffer_dirty(cp_bh);
 365                         nilfs_mdt_mark_dirty(cpfile);
 366                         if (!nilfs_cpfile_is_in_first(cpfile, cno)) {
 367                                 count =
 368                                   nilfs_cpfile_block_sub_valid_checkpoints(
 369                                                 cpfile, cp_bh, kaddr, nicps);
 370                                 if (count == 0) {
 371                                         /* make hole */
 372                                         kunmap_atomic(kaddr);
 373                                         brelse(cp_bh);
 374                                         ret =
 375                                           nilfs_cpfile_delete_checkpoint_block(
 376                                                                    cpfile, cno);
 377                                         if (ret == 0)
 378                                                 continue;
 379                                         nilfs_msg(cpfile->i_sb, KERN_ERR,
 380                                                   "error %d deleting checkpoint block",
 381                                                   ret);
 382                                         break;
 383                                 }
 384                         }
 385                 }
 386
 387                 kunmap_atomic(kaddr);
 388                 brelse(cp_bh);
 389         }
 390
 391         if (tnicps > 0) {
 392                 kaddr = kmap_atomic(header_bh->b_page);
 393                 header = nilfs_cpfile_block_get_header(cpfile, header_bh,
 394                                                        kaddr);
 395                 le64_add_cpu(&header->ch_ncheckpoints, -(u64)tnicps);
 396                 mark_buffer_dirty(header_bh);
 397                 nilfs_mdt_mark_dirty(cpfile);
 398                 kunmap_atomic(kaddr);
 399         }
 400
 401         brelse(header_bh);
 402         if (nss > 0)
 403                 ret = -EBUSY;
 404
 405  out_sem:
 406         up_write(&NILFS_MDT(cpfile)->mi_sem);
 407         return ret;
 408 }
 409
 410 static void nilfs_cpfile_checkpoint_to_cpinfo(struct inode *cpfile,
 411                                               struct nilfs_checkpoint *cp,
 412                                               struct nilfs_cpinfo *ci)
 413 {
 414         ci->ci_flags = le32_to_cpu(cp->cp_flags);
 415         ci->ci_cno = le64_to_cpu(cp->cp_cno);
 416         ci->ci_create = le64_to_cpu(cp->cp_create);
 417         ci->ci_nblk_inc = le64_to_cpu(cp->cp_nblk_inc);
 418         ci->ci_inodes_count = le64_to_cpu(cp->cp_inodes_count);
 419         ci->ci_blocks_count = le64_to_cpu(cp->cp_blocks_count);
 420         ci->ci_next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
 421 }
 422
 423 static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
 424                                           void *buf, unsigned int cisz,
 425                                           size_t nci)
 426 {
 427         struct nilfs_checkpoint *cp;
 428         struct nilfs_cpinfo *ci = buf;
 429         struct buffer_head *bh;
 430         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 431         __u64 cur_cno = nilfs_mdt_cno(cpfile), cno = *cnop;
 432         void *kaddr;
 433         int n, ret;
 434         int ncps, i;
 435
 436         if (cno == 0)
 437                 return -ENOENT; /* checkpoint number 0 is invalid */
 438         down_read(&NILFS_MDT(cpfile)->mi_sem);
 439
 440         for (n = 0; n < nci; cno += ncps) {
 441                 ret = nilfs_cpfile_find_checkpoint_block(
 442                         cpfile, cno, cur_cno - 1, &cno, &bh);
 443                 if (ret < 0) {
 444                         if (likely(ret == -ENOENT))
 445                                 break;
 446                         goto out;
 447                 }
 448                 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
 449
 450                 kaddr = kmap_atomic(bh->b_page);
 451                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 452                 for (i = 0; i < ncps && n < nci; i++, cp = (void *)cp + cpsz) {
 453                         if (!nilfs_checkpoint_invalid(cp)) {
 454                                 nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp,
 455                                                                   ci);
 456                                 ci = (void *)ci + cisz;
 457                                 n++;
 458                         }
 459                 }
 460                 kunmap_atomic(kaddr);
 461                 brelse(bh);
 462         }
 463
 464         ret = n;
 465         if (n > 0) {
 466                 ci = (void *)ci - cisz;
 467                 *cnop = ci->ci_cno + 1;
 468         }
 469
 470  out:
 471         up_read(&NILFS_MDT(cpfile)->mi_sem);
 472         return ret;
 473 }
 474
 475 static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
 476                                           void *buf, unsigned int cisz,
 477                                           size_t nci)
 478 {
 479         struct buffer_head *bh;
 480         struct nilfs_cpfile_header *header;
 481         struct nilfs_checkpoint *cp;
 482         struct nilfs_cpinfo *ci = buf;
 483         __u64 curr = *cnop, next;
 484         unsigned long curr_blkoff, next_blkoff;
 485         void *kaddr;
 486         int n = 0, ret;
 487
 488         down_read(&NILFS_MDT(cpfile)->mi_sem);
 489
 490         if (curr == 0) {
 491                 ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 492                 if (ret < 0)
 493                         goto out;
 494                 kaddr = kmap_atomic(bh->b_page);
 495                 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 496                 curr = le64_to_cpu(header->ch_snapshot_list.ssl_next);
 497                 kunmap_atomic(kaddr);
 498                 brelse(bh);
 499                 if (curr == 0) {
 500                         ret = 0;
 501                         goto out;
 502                 }
 503         } else if (unlikely(curr == ~(__u64)0)) {
 504                 ret = 0;
 505                 goto out;
 506         }
 507
 508         curr_blkoff = nilfs_cpfile_get_blkoff(cpfile, curr);
 509         ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr, 0, &bh);
 510         if (unlikely(ret < 0)) {
 511                 if (ret == -ENOENT)
 512                         ret = 0; /* No snapshots (started from a hole block) */
 513                 goto out;
 514         }
 515         kaddr = kmap_atomic(bh->b_page);
 516         while (n < nci) {
 517                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, curr, bh, kaddr);
 518                 curr = ~(__u64)0; /* Terminator */
 519                 if (unlikely(nilfs_checkpoint_invalid(cp) ||
 520                              !nilfs_checkpoint_snapshot(cp)))
 521                         break;
 522                 nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp, ci);
 523                 ci = (void *)ci + cisz;
 524                 n++;
 525                 next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
 526                 if (next == 0)
 527                         break; /* reach end of the snapshot list */
 528
 529                 next_blkoff = nilfs_cpfile_get_blkoff(cpfile, next);
 530                 if (curr_blkoff != next_blkoff) {
 531                         kunmap_atomic(kaddr);
 532                         brelse(bh);
 533                         ret = nilfs_cpfile_get_checkpoint_block(cpfile, next,
 534                                                                 0, &bh);
 535                         if (unlikely(ret < 0)) {
 536                                 WARN_ON(ret == -ENOENT);
 537                                 goto out;
 538                         }
 539                         kaddr = kmap_atomic(bh->b_page);
 540                 }
 541                 curr = next;
 542                 curr_blkoff = next_blkoff;
 543         }
 544         kunmap_atomic(kaddr);
 545         brelse(bh);
 546         *cnop = curr;
 547         ret = n;
 548
 549  out:
 550         up_read(&NILFS_MDT(cpfile)->mi_sem);
 551         return ret;
 552 }
 553
 554 /**
 555  * nilfs_cpfile_get_cpinfo -
 556  * @cpfile:
 557  * @cno:
 558  * @ci:
 559  * @nci:
 560  */
 561
 562 ssize_t nilfs_cpfile_get_cpinfo(struct inode *cpfile, __u64 *cnop, int mode,
 563                                 void *buf, unsigned int cisz, size_t nci)
 564 {
 565         switch (mode) {
 566         case NILFS_CHECKPOINT:
 567                 return nilfs_cpfile_do_get_cpinfo(cpfile, cnop, buf, cisz, nci);
 568         case NILFS_SNAPSHOT:
 569                 return nilfs_cpfile_do_get_ssinfo(cpfile, cnop, buf, cisz, nci);
 570         default:
 571                 return -EINVAL;
 572         }
 573 }
 574
 575 /**
 576  * nilfs_cpfile_delete_checkpoint -
 577  * @cpfile:
 578  * @cno:
 579  */
 580 int nilfs_cpfile_delete_checkpoint(struct inode *cpfile, __u64 cno)
 581 {
 582         struct nilfs_cpinfo ci;
 583         __u64 tcno = cno;
 584         ssize_t nci;
 585
 586         nci = nilfs_cpfile_do_get_cpinfo(cpfile, &tcno, &ci, sizeof(ci), 1);
 587         if (nci < 0)
 588                 return nci;
 589         else if (nci == 0 || ci.ci_cno != cno)
 590                 return -ENOENT;
 591         else if (nilfs_cpinfo_snapshot(&ci))
 592                 return -EBUSY;
 593
 594         return nilfs_cpfile_delete_checkpoints(cpfile, cno, cno + 1);
 595 }
 596
 597 static struct nilfs_snapshot_list *
 598 nilfs_cpfile_block_get_snapshot_list(const struct inode *cpfile,
 599                                      __u64 cno,
 600                                      struct buffer_head *bh,
 601                                      void *kaddr)
 602 {
 603         struct nilfs_cpfile_header *header;
 604         struct nilfs_checkpoint *cp;
 605         struct nilfs_snapshot_list *list;
 606
 607         if (cno != 0) {
 608                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 609                 list = &cp->cp_snapshot_list;
 610         } else {
 611                 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 612                 list = &header->ch_snapshot_list;
 613         }
 614         return list;
 615 }
 616
 617 static int nilfs_cpfile_set_snapshot(struct inode *cpfile, __u64 cno)
 618 {
 619         struct buffer_head *header_bh, *curr_bh, *prev_bh, *cp_bh;
 620         struct nilfs_cpfile_header *header;
 621         struct nilfs_checkpoint *cp;
 622         struct nilfs_snapshot_list *list;
 623         __u64 curr, prev;
 624         unsigned long curr_blkoff, prev_blkoff;
 625         void *kaddr;
 626         int ret;
 627
 628         if (cno == 0)
 629                 return -ENOENT; /* checkpoint number 0 is invalid */
 630         down_write(&NILFS_MDT(cpfile)->mi_sem);
 631
 632         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 633         if (ret < 0)
 634                 goto out_sem;
 635         kaddr = kmap_atomic(cp_bh->b_page);
 636         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 637         if (nilfs_checkpoint_invalid(cp)) {
 638                 ret = -ENOENT;
 639                 kunmap_atomic(kaddr);
 640                 goto out_cp;
 641         }
 642         if (nilfs_checkpoint_snapshot(cp)) {
 643                 ret = 0;
 644                 kunmap_atomic(kaddr);
 645                 goto out_cp;
 646         }
 647         kunmap_atomic(kaddr);
 648
 649         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 650         if (ret < 0)
 651                 goto out_cp;
 652         kaddr = kmap_atomic(header_bh->b_page);
 653         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 654         list = &header->ch_snapshot_list;
 655         curr_bh = header_bh;
 656         get_bh(curr_bh);
 657         curr = 0;
 658         curr_blkoff = 0;
 659         prev = le64_to_cpu(list->ssl_prev);
 660         while (prev > cno) {
 661                 prev_blkoff = nilfs_cpfile_get_blkoff(cpfile, prev);
 662                 curr = prev;
 663                 if (curr_blkoff != prev_blkoff) {
 664                         kunmap_atomic(kaddr);
 665                         brelse(curr_bh);
 666                         ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr,
 667                                                                 0, &curr_bh);
 668                         if (ret < 0)
 669                                 goto out_header;
 670                         kaddr = kmap_atomic(curr_bh->b_page);
 671                 }
 672                 curr_blkoff = prev_blkoff;
 673                 cp = nilfs_cpfile_block_get_checkpoint(
 674                         cpfile, curr, curr_bh, kaddr);
 675                 list = &cp->cp_snapshot_list;
 676                 prev = le64_to_cpu(list->ssl_prev);
 677         }
 678         kunmap_atomic(kaddr);
 679
 680         if (prev != 0) {
 681                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 682                                                         &prev_bh);
 683                 if (ret < 0)
 684                         goto out_curr;
 685         } else {
 686                 prev_bh = header_bh;
 687                 get_bh(prev_bh);
 688         }
 689
 690         kaddr = kmap_atomic(curr_bh->b_page);
 691         list = nilfs_cpfile_block_get_snapshot_list(
 692                 cpfile, curr, curr_bh, kaddr);
 693         list->ssl_prev = cpu_to_le64(cno);
 694         kunmap_atomic(kaddr);
 695
 696         kaddr = kmap_atomic(cp_bh->b_page);
 697         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 698         cp->cp_snapshot_list.ssl_next = cpu_to_le64(curr);
 699         cp->cp_snapshot_list.ssl_prev = cpu_to_le64(prev);
 700         nilfs_checkpoint_set_snapshot(cp);
 701         kunmap_atomic(kaddr);
 702
 703         kaddr = kmap_atomic(prev_bh->b_page);
 704         list = nilfs_cpfile_block_get_snapshot_list(
 705                 cpfile, prev, prev_bh, kaddr);
 706         list->ssl_next = cpu_to_le64(cno);
 707         kunmap_atomic(kaddr);
 708
 709         kaddr = kmap_atomic(header_bh->b_page);
 710         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 711         le64_add_cpu(&header->ch_nsnapshots, 1);
 712         kunmap_atomic(kaddr);
 713
 714         mark_buffer_dirty(prev_bh);
 715         mark_buffer_dirty(curr_bh);
 716         mark_buffer_dirty(cp_bh);
 717         mark_buffer_dirty(header_bh);
 718         nilfs_mdt_mark_dirty(cpfile);
 719
 720         brelse(prev_bh);
 721
 722  out_curr:
 723         brelse(curr_bh);
 724
 725  out_header:
 726         brelse(header_bh);
 727
 728  out_cp:
 729         brelse(cp_bh);
 730
 731  out_sem:
 732         up_write(&NILFS_MDT(cpfile)->mi_sem);
 733         return ret;
 734 }
 735
 736 static int nilfs_cpfile_clear_snapshot(struct inode *cpfile, __u64 cno)
 737 {
 738         struct buffer_head *header_bh, *next_bh, *prev_bh, *cp_bh;
 739         struct nilfs_cpfile_header *header;
 740         struct nilfs_checkpoint *cp;
 741         struct nilfs_snapshot_list *list;
 742         __u64 next, prev;
 743         void *kaddr;
 744         int ret;
 745
 746         if (cno == 0)
 747                 return -ENOENT; /* checkpoint number 0 is invalid */
 748         down_write(&NILFS_MDT(cpfile)->mi_sem);
 749
 750         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 751         if (ret < 0)
 752                 goto out_sem;
 753         kaddr = kmap_atomic(cp_bh->b_page);
 754         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 755         if (nilfs_checkpoint_invalid(cp)) {
 756                 ret = -ENOENT;
 757                 kunmap_atomic(kaddr);
 758                 goto out_cp;
 759         }
 760         if (!nilfs_checkpoint_snapshot(cp)) {
 761                 ret = 0;
 762                 kunmap_atomic(kaddr);
 763                 goto out_cp;
 764         }
 765
 766         list = &cp->cp_snapshot_list;
 767         next = le64_to_cpu(list->ssl_next);
 768         prev = le64_to_cpu(list->ssl_prev);
 769         kunmap_atomic(kaddr);
 770
 771         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 772         if (ret < 0)
 773                 goto out_cp;
 774         if (next != 0) {
 775                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, next, 0,
 776                                                         &next_bh);
 777                 if (ret < 0)
 778                         goto out_header;
 779         } else {
 780                 next_bh = header_bh;
 781                 get_bh(next_bh);
 782         }
 783         if (prev != 0) {
 784                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 785                                                         &prev_bh);
 786                 if (ret < 0)
 787                         goto out_next;
 788         } else {
 789                 prev_bh = header_bh;
 790                 get_bh(prev_bh);
 791         }
 792
 793         kaddr = kmap_atomic(next_bh->b_page);
 794         list = nilfs_cpfile_block_get_snapshot_list(
 795                 cpfile, next, next_bh, kaddr);
 796         list->ssl_prev = cpu_to_le64(prev);
 797         kunmap_atomic(kaddr);
 798
 799         kaddr = kmap_atomic(prev_bh->b_page);
 800         list = nilfs_cpfile_block_get_snapshot_list(
 801                 cpfile, prev, prev_bh, kaddr);
 802         list->ssl_next = cpu_to_le64(next);
 803         kunmap_atomic(kaddr);
 804
 805         kaddr = kmap_atomic(cp_bh->b_page);
 806         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 807         cp->cp_snapshot_list.ssl_next = cpu_to_le64(0);
 808         cp->cp_snapshot_list.ssl_prev = cpu_to_le64(0);
 809         nilfs_checkpoint_clear_snapshot(cp);
 810         kunmap_atomic(kaddr);
 811
 812         kaddr = kmap_atomic(header_bh->b_page);
 813         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 814         le64_add_cpu(&header->ch_nsnapshots, -1);
 815         kunmap_atomic(kaddr);
 816
 817         mark_buffer_dirty(next_bh);
 818         mark_buffer_dirty(prev_bh);
 819         mark_buffer_dirty(cp_bh);
 820         mark_buffer_dirty(header_bh);
 821         nilfs_mdt_mark_dirty(cpfile);
 822
 823         brelse(prev_bh);
 824
 825  out_next:
 826         brelse(next_bh);
 827
 828  out_header:
 829         brelse(header_bh);
 830
 831  out_cp:
 832         brelse(cp_bh);
 833
 834  out_sem:
 835         up_write(&NILFS_MDT(cpfile)->mi_sem);
 836         return ret;
 837 }
 838
 839 /**
 840  * nilfs_cpfile_is_snapshot -
 841  * @cpfile: inode of checkpoint file
 842  * @cno: checkpoint number
 843  *
 844  * Description:
 845  *
 846  * Return Value: On success, 1 is returned if the checkpoint specified by
 847  * @cno is a snapshot, or 0 if not. On error, one of the following negative
 848  * error codes is returned.
 849  *
 850  * %-EIO - I/O error.
 851  *
 852  * %-ENOMEM - Insufficient amount of memory available.
 853  *
 854  * %-ENOENT - No such checkpoint.
 855  */
 856 int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
 857 {
 858         struct buffer_head *bh;
 859         struct nilfs_checkpoint *cp;
 860         void *kaddr;
 861         int ret;
 862
 863         /*
 864          * CP number is invalid if it's zero or larger than the
 865          * largest existing one.
 866          */
 867         if (cno == 0 || cno >= nilfs_mdt_cno(cpfile))
 868                 return -ENOENT;
 869         down_read(&NILFS_MDT(cpfile)->mi_sem);
 870
 871         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
 872         if (ret < 0)
 873                 goto out;
 874         kaddr = kmap_atomic(bh->b_page);
 875         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 876         if (nilfs_checkpoint_invalid(cp))
 877                 ret = -ENOENT;
 878         else
 879                 ret = nilfs_checkpoint_snapshot(cp);
 880         kunmap_atomic(kaddr);
 881         brelse(bh);
 882
 883  out:
 884         up_read(&NILFS_MDT(cpfile)->mi_sem);
 885         return ret;
 886 }
 887
 888 /**
 889  * nilfs_cpfile_change_cpmode - change checkpoint mode
 890  * @cpfile: inode of checkpoint file
 891  * @cno: checkpoint number
 892  * @status: mode of checkpoint
 893  *
 894  * Description: nilfs_change_cpmode() changes the mode of the checkpoint
 895  * specified by @cno. The mode @mode is NILFS_CHECKPOINT or NILFS_SNAPSHOT.
 896  *
 897  * Return Value: On success, 0 is returned. On error, one of the following
 898  * negative error codes is returned.
 899  *
 900  * %-EIO - I/O error.
 901  *
 902  * %-ENOMEM - Insufficient amount of memory available.
 903  *
 904  * %-ENOENT - No such checkpoint.
 905  */
 906 int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
 907 {
 908         int ret;
 909
 910         switch (mode) {
 911         case NILFS_CHECKPOINT:
 912                 if (nilfs_checkpoint_is_mounted(cpfile->i_sb, cno))
 913                         /*
 914                          * Current implementation does not have to protect
 915                          * plain read-only mounts since they are exclusive
 916                          * with a read/write mount and are protected from the
 917                          * cleaner.
 918                          */
 919                         ret = -EBUSY;
 920                 else
 921                         ret = nilfs_cpfile_clear_snapshot(cpfile, cno);
 922                 return ret;
 923         case NILFS_SNAPSHOT:
 924                 return nilfs_cpfile_set_snapshot(cpfile, cno);
 925         default:
 926                 return -EINVAL;
 927         }
 928 }
 929
 930 /**
 931  * nilfs_cpfile_get_stat - get checkpoint statistics
 932  * @cpfile: inode of checkpoint file
 933  * @stat: pointer to a structure of checkpoint statistics
 934  *
 935  * Description: nilfs_cpfile_get_stat() returns information about checkpoints.
 936  *
 937  * Return Value: On success, 0 is returned, and checkpoints information is
 938  * stored in the place pointed by @stat. On error, one of the following
 939  * negative error codes is returned.
 940  *
 941  * %-EIO - I/O error.
 942  *
 943  * %-ENOMEM - Insufficient amount of memory available.
 944  */
 945 int nilfs_cpfile_get_stat(struct inode *cpfile, struct nilfs_cpstat *cpstat)
 946 {
 947         struct buffer_head *bh;
 948         struct nilfs_cpfile_header *header;
 949         void *kaddr;
 950         int ret;
 951
 952         down_read(&NILFS_MDT(cpfile)->mi_sem);
 953
 954         ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 955         if (ret < 0)
 956                 goto out_sem;
 957         kaddr = kmap_atomic(bh->b_page);
 958         header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 959         cpstat->cs_cno = nilfs_mdt_cno(cpfile);
 960         cpstat->cs_ncps = le64_to_cpu(header->ch_ncheckpoints);
 961         cpstat->cs_nsss = le64_to_cpu(header->ch_nsnapshots);
 962         kunmap_atomic(kaddr);
 963         brelse(bh);
 964
 965  out_sem:
 966         up_read(&NILFS_MDT(cpfile)->mi_sem);
 967         return ret;
 968 }
 969
 970 /**
 971  * nilfs_cpfile_read - read or get cpfile inode
 972  * @sb: super block instance
 973  * @cpsize: size of a checkpoint entry
 974  * @raw_inode: on-disk cpfile inode
 975  * @inodep: buffer to store the inode
 976  */
 977 int nilfs_cpfile_read(struct super_block *sb, size_t cpsize,
 978                       struct nilfs_inode *raw_inode, struct inode **inodep)
 979 {
 980         struct inode *cpfile;
 981         int err;
 982
 983         if (cpsize > sb->s_blocksize) {
 984                 nilfs_msg(sb, KERN_ERR,
 985                           "too large checkpoint size: %zu bytes", cpsize);
 986                 return -EINVAL;
 987         } else if (cpsize < NILFS_MIN_CHECKPOINT_SIZE) {
 988                 nilfs_msg(sb, KERN_ERR,
 989                           "too small checkpoint size: %zu bytes", cpsize);
 990                 return -EINVAL;
 991         }
 992
 993         cpfile = nilfs_iget_locked(sb, NULL, NILFS_CPFILE_INO);
 994         if (unlikely(!cpfile))
 995                 return -ENOMEM;
 996         if (!(cpfile->i_state & I_NEW))
 997                 goto out;
 998
 999         err = nilfs_mdt_init(cpfile, NILFS_MDT_GFP, 0);
1000         if (err)
1001                 goto failed;
1002
1003         nilfs_mdt_set_entry_size(cpfile, cpsize,
1004                                  sizeof(struct nilfs_cpfile_header));
1005
1006         err = nilfs_read_inode_common(cpfile, raw_inode);
1007         if (err)
1008                 goto failed;
1009
1010         unlock_new_inode(cpfile);
1011  out:
1012         *inodep = cpfile;
1013         return 0;
1014  failed:
1015         iget_failed(cpfile);
1016         return err;
1017 }