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 <linux/nilfs2_fs.h>
  25 #include "mdt.h"
  26 #include "cpfile.h"
  27
  28
  29 static inline unsigned long
  30 nilfs_cpfile_checkpoints_per_block(const struct inode *cpfile)
  31 {
  32         return NILFS_MDT(cpfile)->mi_entries_per_block;
  33 }
  34
  35 /* block number from the beginning of the file */
  36 static unsigned long
  37 nilfs_cpfile_get_blkoff(const struct inode *cpfile, __u64 cno)
  38 {
  39         __u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
  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         return do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
  50 }
  51
  52 static __u64 nilfs_cpfile_first_checkpoint_in_block(const struct inode *cpfile,
  53                                                     unsigned long blkoff)
  54 {
  55         return (__u64)nilfs_cpfile_checkpoints_per_block(cpfile) * blkoff
  56                 + 1 - NILFS_MDT(cpfile)->mi_first_entry_offset;
  57 }
  58
  59 static unsigned long
  60 nilfs_cpfile_checkpoints_in_block(const struct inode *cpfile,
  61                                   __u64 curr,
  62                                   __u64 max)
  63 {
  64         return min_t(__u64,
  65                      nilfs_cpfile_checkpoints_per_block(cpfile) -
  66                      nilfs_cpfile_get_offset(cpfile, curr),
  67                      max - curr);
  68 }
  69
  70 static inline int nilfs_cpfile_is_in_first(const struct inode *cpfile,
  71                                            __u64 cno)
  72 {
  73         return nilfs_cpfile_get_blkoff(cpfile, cno) == 0;
  74 }
  75
  76 static unsigned int
  77 nilfs_cpfile_block_add_valid_checkpoints(const struct inode *cpfile,
  78                                          struct buffer_head *bh,
  79                                          void *kaddr,
  80                                          unsigned int n)
  81 {
  82         struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
  83         unsigned int count;
  84
  85         count = le32_to_cpu(cp->cp_checkpoints_count) + n;
  86         cp->cp_checkpoints_count = cpu_to_le32(count);
  87         return count;
  88 }
  89
  90 static unsigned int
  91 nilfs_cpfile_block_sub_valid_checkpoints(const struct inode *cpfile,
  92                                          struct buffer_head *bh,
  93                                          void *kaddr,
  94                                          unsigned int n)
  95 {
  96         struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
  97         unsigned int count;
  98
  99         WARN_ON(le32_to_cpu(cp->cp_checkpoints_count) < n);
 100         count = le32_to_cpu(cp->cp_checkpoints_count) - n;
 101         cp->cp_checkpoints_count = cpu_to_le32(count);
 102         return count;
 103 }
 104
 105 static inline struct nilfs_cpfile_header *
 106 nilfs_cpfile_block_get_header(const struct inode *cpfile,
 107                               struct buffer_head *bh,
 108                               void *kaddr)
 109 {
 110         return kaddr + bh_offset(bh);
 111 }
 112
 113 static struct nilfs_checkpoint *
 114 nilfs_cpfile_block_get_checkpoint(const struct inode *cpfile, __u64 cno,
 115                                   struct buffer_head *bh,
 116                                   void *kaddr)
 117 {
 118         return kaddr + bh_offset(bh) + nilfs_cpfile_get_offset(cpfile, cno) *
 119                 NILFS_MDT(cpfile)->mi_entry_size;
 120 }
 121
 122 static void nilfs_cpfile_block_init(struct inode *cpfile,
 123                                     struct buffer_head *bh,
 124                                     void *kaddr)
 125 {
 126         struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
 127         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 128         int n = nilfs_cpfile_checkpoints_per_block(cpfile);
 129
 130         while (n-- > 0) {
 131                 nilfs_checkpoint_set_invalid(cp);
 132                 cp = (void *)cp + cpsz;
 133         }
 134 }
 135
 136 static inline int nilfs_cpfile_get_header_block(struct inode *cpfile,
 137                                                 struct buffer_head **bhp)
 138 {
 139         return nilfs_mdt_get_block(cpfile, 0, 0, NULL, bhp);
 140 }
 141
 142 static inline int nilfs_cpfile_get_checkpoint_block(struct inode *cpfile,
 143                                                     __u64 cno,
 144                                                     int create,
 145                                                     struct buffer_head **bhp)
 146 {
 147         return nilfs_mdt_get_block(cpfile,
 148                                    nilfs_cpfile_get_blkoff(cpfile, cno),
 149                                    create, nilfs_cpfile_block_init, bhp);
 150 }
 151
 152 /**
 153  * nilfs_cpfile_find_checkpoint_block - find and get a buffer on cpfile
 154  * @cpfile: inode of cpfile
 155  * @start_cno: start checkpoint number (inclusive)
 156  * @end_cno: end checkpoint number (inclusive)
 157  * @cnop: place to store the next checkpoint number
 158  * @bhp: place to store a pointer to buffer_head struct
 159  *
 160  * Return Value: On success, it returns 0. On error, the following negative
 161  * error code is returned.
 162  *
 163  * %-ENOMEM - Insufficient memory available.
 164  *
 165  * %-EIO - I/O error
 166  *
 167  * %-ENOENT - no block exists in the range.
 168  */
 169 static int nilfs_cpfile_find_checkpoint_block(struct inode *cpfile,
 170                                               __u64 start_cno, __u64 end_cno,
 171                                               __u64 *cnop,
 172                                               struct buffer_head **bhp)
 173 {
 174         unsigned long start, end, blkoff;
 175         int ret;
 176
 177         if (unlikely(start_cno > end_cno))
 178                 return -ENOENT;
 179
 180         start = nilfs_cpfile_get_blkoff(cpfile, start_cno);
 181         end = nilfs_cpfile_get_blkoff(cpfile, end_cno);
 182
 183         ret = nilfs_mdt_find_block(cpfile, start, end, &blkoff, bhp);
 184         if (!ret)
 185                 *cnop = (blkoff == start) ? start_cno :
 186                         nilfs_cpfile_first_checkpoint_in_block(cpfile, blkoff);
 187         return ret;
 188 }
 189
 190 static inline int nilfs_cpfile_delete_checkpoint_block(struct inode *cpfile,
 191                                                        __u64 cno)
 192 {
 193         return nilfs_mdt_delete_block(cpfile,
 194                                       nilfs_cpfile_get_blkoff(cpfile, cno));
 195 }
 196
 197 /**
 198  * nilfs_cpfile_get_checkpoint - get a checkpoint
 199  * @cpfile: inode of checkpoint file
 200  * @cno: checkpoint number
 201  * @create: create flag
 202  * @cpp: pointer to a checkpoint
 203  * @bhp: pointer to a buffer head
 204  *
 205  * Description: nilfs_cpfile_get_checkpoint() acquires the checkpoint
 206  * specified by @cno. A new checkpoint will be created if @cno is the current
 207  * checkpoint number and @create is nonzero.
 208  *
 209  * Return Value: On success, 0 is returned, and the checkpoint and the
 210  * buffer head of the buffer on which the checkpoint is located are stored in
 211  * the place pointed by @cpp and @bhp, respectively. On error, one of the
 212  * following negative error codes is returned.
 213  *
 214  * %-EIO - I/O error.
 215  *
 216  * %-ENOMEM - Insufficient amount of memory available.
 217  *
 218  * %-ENOENT - No such checkpoint.
 219  *
 220  * %-EINVAL - invalid checkpoint.
 221  */
 222 int nilfs_cpfile_get_checkpoint(struct inode *cpfile,
 223                                 __u64 cno,
 224                                 int create,
 225                                 struct nilfs_checkpoint **cpp,
 226                                 struct buffer_head **bhp)
 227 {
 228         struct buffer_head *header_bh, *cp_bh;
 229         struct nilfs_cpfile_header *header;
 230         struct nilfs_checkpoint *cp;
 231         void *kaddr;
 232         int ret;
 233
 234         if (unlikely(cno < 1 || cno > nilfs_mdt_cno(cpfile) ||
 235                      (cno < nilfs_mdt_cno(cpfile) && create)))
 236                 return -EINVAL;
 237
 238         down_write(&NILFS_MDT(cpfile)->mi_sem);
 239
 240         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 241         if (ret < 0)
 242                 goto out_sem;
 243         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, create, &cp_bh);
 244         if (ret < 0)
 245                 goto out_header;
 246         kaddr = kmap(cp_bh->b_page);
 247         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 248         if (nilfs_checkpoint_invalid(cp)) {
 249                 if (!create) {
 250                         kunmap(cp_bh->b_page);
 251                         brelse(cp_bh);
 252                         ret = -ENOENT;
 253                         goto out_header;
 254                 }
 255                 /* a newly-created checkpoint */
 256                 nilfs_checkpoint_clear_invalid(cp);
 257                 if (!nilfs_cpfile_is_in_first(cpfile, cno))
 258                         nilfs_cpfile_block_add_valid_checkpoints(cpfile, cp_bh,
 259                                                                  kaddr, 1);
 260                 mark_buffer_dirty(cp_bh);
 261
 262                 kaddr = kmap_atomic(header_bh->b_page);
 263                 header = nilfs_cpfile_block_get_header(cpfile, header_bh,
 264                                                        kaddr);
 265                 le64_add_cpu(&header->ch_ncheckpoints, 1);
 266                 kunmap_atomic(kaddr);
 267                 mark_buffer_dirty(header_bh);
 268                 nilfs_mdt_mark_dirty(cpfile);
 269         }
 270
 271         if (cpp != NULL)
 272                 *cpp = cp;
 273         *bhp = cp_bh;
 274
 275  out_header:
 276         brelse(header_bh);
 277
 278  out_sem:
 279         up_write(&NILFS_MDT(cpfile)->mi_sem);
 280         return ret;
 281 }
 282
 283 /**
 284  * nilfs_cpfile_put_checkpoint - put a checkpoint
 285  * @cpfile: inode of checkpoint file
 286  * @cno: checkpoint number
 287  * @bh: buffer head
 288  *
 289  * Description: nilfs_cpfile_put_checkpoint() releases the checkpoint
 290  * specified by @cno. @bh must be the buffer head which has been returned by
 291  * a previous call to nilfs_cpfile_get_checkpoint() with @cno.
 292  */
 293 void nilfs_cpfile_put_checkpoint(struct inode *cpfile, __u64 cno,
 294                                  struct buffer_head *bh)
 295 {
 296         kunmap(bh->b_page);
 297         brelse(bh);
 298 }
 299
 300 /**
 301  * nilfs_cpfile_delete_checkpoints - delete checkpoints
 302  * @cpfile: inode of checkpoint file
 303  * @start: start checkpoint number
 304  * @end: end checkpoint numer
 305  *
 306  * Description: nilfs_cpfile_delete_checkpoints() deletes the checkpoints in
 307  * the period from @start to @end, excluding @end itself. The checkpoints
 308  * which have been already deleted are ignored.
 309  *
 310  * Return Value: On success, 0 is returned. On error, one of the following
 311  * negative error codes is returned.
 312  *
 313  * %-EIO - I/O error.
 314  *
 315  * %-ENOMEM - Insufficient amount of memory available.
 316  *
 317  * %-EINVAL - invalid checkpoints.
 318  */
 319 int nilfs_cpfile_delete_checkpoints(struct inode *cpfile,
 320                                     __u64 start,
 321                                     __u64 end)
 322 {
 323         struct buffer_head *header_bh, *cp_bh;
 324         struct nilfs_cpfile_header *header;
 325         struct nilfs_checkpoint *cp;
 326         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 327         __u64 cno;
 328         void *kaddr;
 329         unsigned long tnicps;
 330         int ret, ncps, nicps, nss, count, i;
 331
 332         if (unlikely(start == 0 || start > end)) {
 333                 printk(KERN_ERR "%s: invalid range of checkpoint numbers: "
 334                        "[%llu, %llu)\n", __func__,
 335                        (unsigned long long)start, (unsigned long long)end);
 336                 return -EINVAL;
 337         }
 338
 339         down_write(&NILFS_MDT(cpfile)->mi_sem);
 340
 341         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 342         if (ret < 0)
 343                 goto out_sem;
 344         tnicps = 0;
 345         nss = 0;
 346
 347         for (cno = start; cno < end; cno += ncps) {
 348                 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, end);
 349                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 350                 if (ret < 0) {
 351                         if (ret != -ENOENT)
 352                                 break;
 353                         /* skip hole */
 354                         ret = 0;
 355                         continue;
 356                 }
 357
 358                 kaddr = kmap_atomic(cp_bh->b_page);
 359                 cp = nilfs_cpfile_block_get_checkpoint(
 360                         cpfile, cno, cp_bh, kaddr);
 361                 nicps = 0;
 362                 for (i = 0; i < ncps; i++, cp = (void *)cp + cpsz) {
 363                         if (nilfs_checkpoint_snapshot(cp)) {
 364                                 nss++;
 365                         } else if (!nilfs_checkpoint_invalid(cp)) {
 366                                 nilfs_checkpoint_set_invalid(cp);
 367                                 nicps++;
 368                         }
 369                 }
 370                 if (nicps > 0) {
 371                         tnicps += nicps;
 372                         mark_buffer_dirty(cp_bh);
 373                         nilfs_mdt_mark_dirty(cpfile);
 374                         if (!nilfs_cpfile_is_in_first(cpfile, cno)) {
 375                                 count =
 376                                   nilfs_cpfile_block_sub_valid_checkpoints(
 377                                                 cpfile, cp_bh, kaddr, nicps);
 378                                 if (count == 0) {
 379                                         /* make hole */
 380                                         kunmap_atomic(kaddr);
 381                                         brelse(cp_bh);
 382                                         ret =
 383                                           nilfs_cpfile_delete_checkpoint_block(
 384                                                                    cpfile, cno);
 385                                         if (ret == 0)
 386                                                 continue;
 387                                         printk(KERN_ERR
 388                                                "%s: cannot delete block\n",
 389                                                __func__);
 390                                         break;
 391                                 }
 392                         }
 393                 }
 394
 395                 kunmap_atomic(kaddr);
 396                 brelse(cp_bh);
 397         }
 398
 399         if (tnicps > 0) {
 400                 kaddr = kmap_atomic(header_bh->b_page);
 401                 header = nilfs_cpfile_block_get_header(cpfile, header_bh,
 402                                                        kaddr);
 403                 le64_add_cpu(&header->ch_ncheckpoints, -(u64)tnicps);
 404                 mark_buffer_dirty(header_bh);
 405                 nilfs_mdt_mark_dirty(cpfile);
 406                 kunmap_atomic(kaddr);
 407         }
 408
 409         brelse(header_bh);
 410         if (nss > 0)
 411                 ret = -EBUSY;
 412
 413  out_sem:
 414         up_write(&NILFS_MDT(cpfile)->mi_sem);
 415         return ret;
 416 }
 417
 418 static void nilfs_cpfile_checkpoint_to_cpinfo(struct inode *cpfile,
 419                                               struct nilfs_checkpoint *cp,
 420                                               struct nilfs_cpinfo *ci)
 421 {
 422         ci->ci_flags = le32_to_cpu(cp->cp_flags);
 423         ci->ci_cno = le64_to_cpu(cp->cp_cno);
 424         ci->ci_create = le64_to_cpu(cp->cp_create);
 425         ci->ci_nblk_inc = le64_to_cpu(cp->cp_nblk_inc);
 426         ci->ci_inodes_count = le64_to_cpu(cp->cp_inodes_count);
 427         ci->ci_blocks_count = le64_to_cpu(cp->cp_blocks_count);
 428         ci->ci_next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
 429 }
 430
 431 static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
 432                                           void *buf, unsigned cisz, size_t nci)
 433 {
 434         struct nilfs_checkpoint *cp;
 435         struct nilfs_cpinfo *ci = buf;
 436         struct buffer_head *bh;
 437         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 438         __u64 cur_cno = nilfs_mdt_cno(cpfile), cno = *cnop;
 439         void *kaddr;
 440         int n, ret;
 441         int ncps, i;
 442
 443         if (cno == 0)
 444                 return -ENOENT; /* checkpoint number 0 is invalid */
 445         down_read(&NILFS_MDT(cpfile)->mi_sem);
 446
 447         for (n = 0; n < nci; cno += ncps) {
 448                 ret = nilfs_cpfile_find_checkpoint_block(
 449                         cpfile, cno, cur_cno - 1, &cno, &bh);
 450                 if (ret < 0) {
 451                         if (likely(ret == -ENOENT))
 452                                 break;
 453                         goto out;
 454                 }
 455                 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
 456
 457                 kaddr = kmap_atomic(bh->b_page);
 458                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 459                 for (i = 0; i < ncps && n < nci; i++, cp = (void *)cp + cpsz) {
 460                         if (!nilfs_checkpoint_invalid(cp)) {
 461                                 nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp,
 462                                                                   ci);
 463                                 ci = (void *)ci + cisz;
 464                                 n++;
 465                         }
 466                 }
 467                 kunmap_atomic(kaddr);
 468                 brelse(bh);
 469         }
 470
 471         ret = n;
 472         if (n > 0) {
 473                 ci = (void *)ci - cisz;
 474                 *cnop = ci->ci_cno + 1;
 475         }
 476
 477  out:
 478         up_read(&NILFS_MDT(cpfile)->mi_sem);
 479         return ret;
 480 }
 481
 482 static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
 483                                           void *buf, unsigned cisz, size_t nci)
 484 {
 485         struct buffer_head *bh;
 486         struct nilfs_cpfile_header *header;
 487         struct nilfs_checkpoint *cp;
 488         struct nilfs_cpinfo *ci = buf;
 489         __u64 curr = *cnop, next;
 490         unsigned long curr_blkoff, next_blkoff;
 491         void *kaddr;
 492         int n = 0, ret;
 493
 494         down_read(&NILFS_MDT(cpfile)->mi_sem);
 495
 496         if (curr == 0) {
 497                 ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 498                 if (ret < 0)
 499                         goto out;
 500                 kaddr = kmap_atomic(bh->b_page);
 501                 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 502                 curr = le64_to_cpu(header->ch_snapshot_list.ssl_next);
 503                 kunmap_atomic(kaddr);
 504                 brelse(bh);
 505                 if (curr == 0) {
 506                         ret = 0;
 507                         goto out;
 508                 }
 509         } else if (unlikely(curr == ~(__u64)0)) {
 510                 ret = 0;
 511                 goto out;
 512         }
 513
 514         curr_blkoff = nilfs_cpfile_get_blkoff(cpfile, curr);
 515         ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr, 0, &bh);
 516         if (unlikely(ret < 0)) {
 517                 if (ret == -ENOENT)
 518                         ret = 0; /* No snapshots (started from a hole block) */
 519                 goto out;
 520         }
 521         kaddr = kmap_atomic(bh->b_page);
 522         while (n < nci) {
 523                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, curr, bh, kaddr);
 524                 curr = ~(__u64)0; /* Terminator */
 525                 if (unlikely(nilfs_checkpoint_invalid(cp) ||
 526                              !nilfs_checkpoint_snapshot(cp)))
 527                         break;
 528                 nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp, ci);
 529                 ci = (void *)ci + cisz;
 530                 n++;
 531                 next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
 532                 if (next == 0)
 533                         break; /* reach end of the snapshot list */
 534
 535                 next_blkoff = nilfs_cpfile_get_blkoff(cpfile, next);
 536                 if (curr_blkoff != next_blkoff) {
 537                         kunmap_atomic(kaddr);
 538                         brelse(bh);
 539                         ret = nilfs_cpfile_get_checkpoint_block(cpfile, next,
 540                                                                 0, &bh);
 541                         if (unlikely(ret < 0)) {
 542                                 WARN_ON(ret == -ENOENT);
 543                                 goto out;
 544                         }
 545                         kaddr = kmap_atomic(bh->b_page);
 546                 }
 547                 curr = next;
 548                 curr_blkoff = next_blkoff;
 549         }
 550         kunmap_atomic(kaddr);
 551         brelse(bh);
 552         *cnop = curr;
 553         ret = n;
 554
 555  out:
 556         up_read(&NILFS_MDT(cpfile)->mi_sem);
 557         return ret;
 558 }
 559
 560 /**
 561  * nilfs_cpfile_get_cpinfo -
 562  * @cpfile:
 563  * @cno:
 564  * @ci:
 565  * @nci:
 566  */
 567
 568 ssize_t nilfs_cpfile_get_cpinfo(struct inode *cpfile, __u64 *cnop, int mode,
 569                                 void *buf, unsigned cisz, size_t nci)
 570 {
 571         switch (mode) {
 572         case NILFS_CHECKPOINT:
 573                 return nilfs_cpfile_do_get_cpinfo(cpfile, cnop, buf, cisz, nci);
 574         case NILFS_SNAPSHOT:
 575                 return nilfs_cpfile_do_get_ssinfo(cpfile, cnop, buf, cisz, nci);
 576         default:
 577                 return -EINVAL;
 578         }
 579 }
 580
 581 /**
 582  * nilfs_cpfile_delete_checkpoint -
 583  * @cpfile:
 584  * @cno:
 585  */
 586 int nilfs_cpfile_delete_checkpoint(struct inode *cpfile, __u64 cno)
 587 {
 588         struct nilfs_cpinfo ci;
 589         __u64 tcno = cno;
 590         ssize_t nci;
 591
 592         nci = nilfs_cpfile_do_get_cpinfo(cpfile, &tcno, &ci, sizeof(ci), 1);
 593         if (nci < 0)
 594                 return nci;
 595         else if (nci == 0 || ci.ci_cno != cno)
 596                 return -ENOENT;
 597         else if (nilfs_cpinfo_snapshot(&ci))
 598                 return -EBUSY;
 599
 600         return nilfs_cpfile_delete_checkpoints(cpfile, cno, cno + 1);
 601 }
 602
 603 static struct nilfs_snapshot_list *
 604 nilfs_cpfile_block_get_snapshot_list(const struct inode *cpfile,
 605                                      __u64 cno,
 606                                      struct buffer_head *bh,
 607                                      void *kaddr)
 608 {
 609         struct nilfs_cpfile_header *header;
 610         struct nilfs_checkpoint *cp;
 611         struct nilfs_snapshot_list *list;
 612
 613         if (cno != 0) {
 614                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 615                 list = &cp->cp_snapshot_list;
 616         } else {
 617                 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 618                 list = &header->ch_snapshot_list;
 619         }
 620         return list;
 621 }
 622
 623 static int nilfs_cpfile_set_snapshot(struct inode *cpfile, __u64 cno)
 624 {
 625         struct buffer_head *header_bh, *curr_bh, *prev_bh, *cp_bh;
 626         struct nilfs_cpfile_header *header;
 627         struct nilfs_checkpoint *cp;
 628         struct nilfs_snapshot_list *list;
 629         __u64 curr, prev;
 630         unsigned long curr_blkoff, prev_blkoff;
 631         void *kaddr;
 632         int ret;
 633
 634         if (cno == 0)
 635                 return -ENOENT; /* checkpoint number 0 is invalid */
 636         down_write(&NILFS_MDT(cpfile)->mi_sem);
 637
 638         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 639         if (ret < 0)
 640                 goto out_sem;
 641         kaddr = kmap_atomic(cp_bh->b_page);
 642         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 643         if (nilfs_checkpoint_invalid(cp)) {
 644                 ret = -ENOENT;
 645                 kunmap_atomic(kaddr);
 646                 goto out_cp;
 647         }
 648         if (nilfs_checkpoint_snapshot(cp)) {
 649                 ret = 0;
 650                 kunmap_atomic(kaddr);
 651                 goto out_cp;
 652         }
 653         kunmap_atomic(kaddr);
 654
 655         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 656         if (ret < 0)
 657                 goto out_cp;
 658         kaddr = kmap_atomic(header_bh->b_page);
 659         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 660         list = &header->ch_snapshot_list;
 661         curr_bh = header_bh;
 662         get_bh(curr_bh);
 663         curr = 0;
 664         curr_blkoff = 0;
 665         prev = le64_to_cpu(list->ssl_prev);
 666         while (prev > cno) {
 667                 prev_blkoff = nilfs_cpfile_get_blkoff(cpfile, prev);
 668                 curr = prev;
 669                 if (curr_blkoff != prev_blkoff) {
 670                         kunmap_atomic(kaddr);
 671                         brelse(curr_bh);
 672                         ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr,
 673                                                                 0, &curr_bh);
 674                         if (ret < 0)
 675                                 goto out_header;
 676                         kaddr = kmap_atomic(curr_bh->b_page);
 677                 }
 678                 curr_blkoff = prev_blkoff;
 679                 cp = nilfs_cpfile_block_get_checkpoint(
 680                         cpfile, curr, curr_bh, kaddr);
 681                 list = &cp->cp_snapshot_list;
 682                 prev = le64_to_cpu(list->ssl_prev);
 683         }
 684         kunmap_atomic(kaddr);
 685
 686         if (prev != 0) {
 687                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 688                                                         &prev_bh);
 689                 if (ret < 0)
 690                         goto out_curr;
 691         } else {
 692                 prev_bh = header_bh;
 693                 get_bh(prev_bh);
 694         }
 695
 696         kaddr = kmap_atomic(curr_bh->b_page);
 697         list = nilfs_cpfile_block_get_snapshot_list(
 698                 cpfile, curr, curr_bh, kaddr);
 699         list->ssl_prev = cpu_to_le64(cno);
 700         kunmap_atomic(kaddr);
 701
 702         kaddr = kmap_atomic(cp_bh->b_page);
 703         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 704         cp->cp_snapshot_list.ssl_next = cpu_to_le64(curr);
 705         cp->cp_snapshot_list.ssl_prev = cpu_to_le64(prev);
 706         nilfs_checkpoint_set_snapshot(cp);
 707         kunmap_atomic(kaddr);
 708
 709         kaddr = kmap_atomic(prev_bh->b_page);
 710         list = nilfs_cpfile_block_get_snapshot_list(
 711                 cpfile, prev, prev_bh, kaddr);
 712         list->ssl_next = cpu_to_le64(cno);
 713         kunmap_atomic(kaddr);
 714
 715         kaddr = kmap_atomic(header_bh->b_page);
 716         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 717         le64_add_cpu(&header->ch_nsnapshots, 1);
 718         kunmap_atomic(kaddr);
 719
 720         mark_buffer_dirty(prev_bh);
 721         mark_buffer_dirty(curr_bh);
 722         mark_buffer_dirty(cp_bh);
 723         mark_buffer_dirty(header_bh);
 724         nilfs_mdt_mark_dirty(cpfile);
 725
 726         brelse(prev_bh);
 727
 728  out_curr:
 729         brelse(curr_bh);
 730
 731  out_header:
 732         brelse(header_bh);
 733
 734  out_cp:
 735         brelse(cp_bh);
 736
 737  out_sem:
 738         up_write(&NILFS_MDT(cpfile)->mi_sem);
 739         return ret;
 740 }
 741
 742 static int nilfs_cpfile_clear_snapshot(struct inode *cpfile, __u64 cno)
 743 {
 744         struct buffer_head *header_bh, *next_bh, *prev_bh, *cp_bh;
 745         struct nilfs_cpfile_header *header;
 746         struct nilfs_checkpoint *cp;
 747         struct nilfs_snapshot_list *list;
 748         __u64 next, prev;
 749         void *kaddr;
 750         int ret;
 751
 752         if (cno == 0)
 753                 return -ENOENT; /* checkpoint number 0 is invalid */
 754         down_write(&NILFS_MDT(cpfile)->mi_sem);
 755
 756         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 757         if (ret < 0)
 758                 goto out_sem;
 759         kaddr = kmap_atomic(cp_bh->b_page);
 760         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 761         if (nilfs_checkpoint_invalid(cp)) {
 762                 ret = -ENOENT;
 763                 kunmap_atomic(kaddr);
 764                 goto out_cp;
 765         }
 766         if (!nilfs_checkpoint_snapshot(cp)) {
 767                 ret = 0;
 768                 kunmap_atomic(kaddr);
 769                 goto out_cp;
 770         }
 771
 772         list = &cp->cp_snapshot_list;
 773         next = le64_to_cpu(list->ssl_next);
 774         prev = le64_to_cpu(list->ssl_prev);
 775         kunmap_atomic(kaddr);
 776
 777         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 778         if (ret < 0)
 779                 goto out_cp;
 780         if (next != 0) {
 781                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, next, 0,
 782                                                         &next_bh);
 783                 if (ret < 0)
 784                         goto out_header;
 785         } else {
 786                 next_bh = header_bh;
 787                 get_bh(next_bh);
 788         }
 789         if (prev != 0) {
 790                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 791                                                         &prev_bh);
 792                 if (ret < 0)
 793                         goto out_next;
 794         } else {
 795                 prev_bh = header_bh;
 796                 get_bh(prev_bh);
 797         }
 798
 799         kaddr = kmap_atomic(next_bh->b_page);
 800         list = nilfs_cpfile_block_get_snapshot_list(
 801                 cpfile, next, next_bh, kaddr);
 802         list->ssl_prev = cpu_to_le64(prev);
 803         kunmap_atomic(kaddr);
 804
 805         kaddr = kmap_atomic(prev_bh->b_page);
 806         list = nilfs_cpfile_block_get_snapshot_list(
 807                 cpfile, prev, prev_bh, kaddr);
 808         list->ssl_next = cpu_to_le64(next);
 809         kunmap_atomic(kaddr);
 810
 811         kaddr = kmap_atomic(cp_bh->b_page);
 812         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 813         cp->cp_snapshot_list.ssl_next = cpu_to_le64(0);
 814         cp->cp_snapshot_list.ssl_prev = cpu_to_le64(0);
 815         nilfs_checkpoint_clear_snapshot(cp);
 816         kunmap_atomic(kaddr);
 817
 818         kaddr = kmap_atomic(header_bh->b_page);
 819         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 820         le64_add_cpu(&header->ch_nsnapshots, -1);
 821         kunmap_atomic(kaddr);
 822
 823         mark_buffer_dirty(next_bh);
 824         mark_buffer_dirty(prev_bh);
 825         mark_buffer_dirty(cp_bh);
 826         mark_buffer_dirty(header_bh);
 827         nilfs_mdt_mark_dirty(cpfile);
 828
 829         brelse(prev_bh);
 830
 831  out_next:
 832         brelse(next_bh);
 833
 834  out_header:
 835         brelse(header_bh);
 836
 837  out_cp:
 838         brelse(cp_bh);
 839
 840  out_sem:
 841         up_write(&NILFS_MDT(cpfile)->mi_sem);
 842         return ret;
 843 }
 844
 845 /**
 846  * nilfs_cpfile_is_snapshot -
 847  * @cpfile: inode of checkpoint file
 848  * @cno: checkpoint number
 849  *
 850  * Description:
 851  *
 852  * Return Value: On success, 1 is returned if the checkpoint specified by
 853  * @cno is a snapshot, or 0 if not. On error, one of the following negative
 854  * error codes is returned.
 855  *
 856  * %-EIO - I/O error.
 857  *
 858  * %-ENOMEM - Insufficient amount of memory available.
 859  *
 860  * %-ENOENT - No such checkpoint.
 861  */
 862 int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
 863 {
 864         struct buffer_head *bh;
 865         struct nilfs_checkpoint *cp;
 866         void *kaddr;
 867         int ret;
 868
 869         /* CP number is invalid if it's zero or larger than the
 870         largest exist one.*/
 871         if (cno == 0 || cno >= nilfs_mdt_cno(cpfile))
 872                 return -ENOENT;
 873         down_read(&NILFS_MDT(cpfile)->mi_sem);
 874
 875         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
 876         if (ret < 0)
 877                 goto out;
 878         kaddr = kmap_atomic(bh->b_page);
 879         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 880         if (nilfs_checkpoint_invalid(cp))
 881                 ret = -ENOENT;
 882         else
 883                 ret = nilfs_checkpoint_snapshot(cp);
 884         kunmap_atomic(kaddr);
 885         brelse(bh);
 886
 887  out:
 888         up_read(&NILFS_MDT(cpfile)->mi_sem);
 889         return ret;
 890 }
 891
 892 /**
 893  * nilfs_cpfile_change_cpmode - change checkpoint mode
 894  * @cpfile: inode of checkpoint file
 895  * @cno: checkpoint number
 896  * @status: mode of checkpoint
 897  *
 898  * Description: nilfs_change_cpmode() changes the mode of the checkpoint
 899  * specified by @cno. The mode @mode is NILFS_CHECKPOINT or NILFS_SNAPSHOT.
 900  *
 901  * Return Value: On success, 0 is returned. On error, one of the following
 902  * negative error codes is returned.
 903  *
 904  * %-EIO - I/O error.
 905  *
 906  * %-ENOMEM - Insufficient amount of memory available.
 907  *
 908  * %-ENOENT - No such checkpoint.
 909  */
 910 int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
 911 {
 912         int ret;
 913
 914         switch (mode) {
 915         case NILFS_CHECKPOINT:
 916                 if (nilfs_checkpoint_is_mounted(cpfile->i_sb, cno))
 917                         /*
 918                          * Current implementation does not have to protect
 919                          * plain read-only mounts since they are exclusive
 920                          * with a read/write mount and are protected from the
 921                          * cleaner.
 922                          */
 923                         ret = -EBUSY;
 924                 else
 925                         ret = nilfs_cpfile_clear_snapshot(cpfile, cno);
 926                 return ret;
 927         case NILFS_SNAPSHOT:
 928                 return nilfs_cpfile_set_snapshot(cpfile, cno);
 929         default:
 930                 return -EINVAL;
 931         }
 932 }
 933
 934 /**
 935  * nilfs_cpfile_get_stat - get checkpoint statistics
 936  * @cpfile: inode of checkpoint file
 937  * @stat: pointer to a structure of checkpoint statistics
 938  *
 939  * Description: nilfs_cpfile_get_stat() returns information about checkpoints.
 940  *
 941  * Return Value: On success, 0 is returned, and checkpoints information is
 942  * stored in the place pointed by @stat. On error, one of the following
 943  * negative error codes is returned.
 944  *
 945  * %-EIO - I/O error.
 946  *
 947  * %-ENOMEM - Insufficient amount of memory available.
 948  */
 949 int nilfs_cpfile_get_stat(struct inode *cpfile, struct nilfs_cpstat *cpstat)
 950 {
 951         struct buffer_head *bh;
 952         struct nilfs_cpfile_header *header;
 953         void *kaddr;
 954         int ret;
 955
 956         down_read(&NILFS_MDT(cpfile)->mi_sem);
 957
 958         ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 959         if (ret < 0)
 960                 goto out_sem;
 961         kaddr = kmap_atomic(bh->b_page);
 962         header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 963         cpstat->cs_cno = nilfs_mdt_cno(cpfile);
 964         cpstat->cs_ncps = le64_to_cpu(header->ch_ncheckpoints);
 965         cpstat->cs_nsss = le64_to_cpu(header->ch_nsnapshots);
 966         kunmap_atomic(kaddr);
 967         brelse(bh);
 968
 969  out_sem:
 970         up_read(&NILFS_MDT(cpfile)->mi_sem);
 971         return ret;
 972 }
 973
 974 /**
 975  * nilfs_cpfile_read - read or get cpfile inode
 976  * @sb: super block instance
 977  * @cpsize: size of a checkpoint entry
 978  * @raw_inode: on-disk cpfile inode
 979  * @inodep: buffer to store the inode
 980  */
 981 int nilfs_cpfile_read(struct super_block *sb, size_t cpsize,
 982                       struct nilfs_inode *raw_inode, struct inode **inodep)
 983 {
 984         struct inode *cpfile;
 985         int err;
 986
 987         if (cpsize > sb->s_blocksize) {
 988                 printk(KERN_ERR
 989                        "NILFS: too large checkpoint size: %zu bytes.\n",
 990                        cpsize);
 991                 return -EINVAL;
 992         } else if (cpsize < NILFS_MIN_CHECKPOINT_SIZE) {
 993                 printk(KERN_ERR
 994                        "NILFS: too small checkpoint size: %zu bytes.\n",
 995                        cpsize);
 996                 return -EINVAL;
 997         }
 998
 999         cpfile = nilfs_iget_locked(sb, NULL, NILFS_CPFILE_INO);
1000         if (unlikely(!cpfile))
1001                 return -ENOMEM;
1002         if (!(cpfile->i_state & I_NEW))
1003                 goto out;
1004
1005         err = nilfs_mdt_init(cpfile, NILFS_MDT_GFP, 0);
1006         if (err)
1007                 goto failed;
1008
1009         nilfs_mdt_set_entry_size(cpfile, cpsize,
1010                                  sizeof(struct nilfs_cpfile_header));
1011
1012         err = nilfs_read_inode_common(cpfile, raw_inode);
1013         if (err)
1014                 goto failed;
1015
1016         unlock_new_inode(cpfile);
1017  out:
1018         *inodep = cpfile;
1019         return 0;
1020  failed:
1021         iget_failed(cpfile);
1022         return err;
1023 }