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  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19  *
  20  * Written by Koji Sato <[email protected]>.
  21  */
  22
  23 #include <linux/kernel.h>
  24 #include <linux/fs.h>
  25 #include <linux/string.h>
  26 #include <linux/buffer_head.h>
  27 #include <linux/errno.h>
  28 #include <linux/nilfs2_fs.h>
  29 #include "mdt.h"
  30 #include "cpfile.h"
  31
  32
  33 static inline unsigned long
  34 nilfs_cpfile_checkpoints_per_block(const struct inode *cpfile)
  35 {
  36         return NILFS_MDT(cpfile)->mi_entries_per_block;
  37 }
  38
  39 /* block number from the beginning of the file */
  40 static unsigned long
  41 nilfs_cpfile_get_blkoff(const struct inode *cpfile, __u64 cno)
  42 {
  43         __u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
  44         do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
  45         return (unsigned long)tcno;
  46 }
  47
  48 /* offset in block */
  49 static unsigned long
  50 nilfs_cpfile_get_offset(const struct inode *cpfile, __u64 cno)
  51 {
  52         __u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
  53         return do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
  54 }
  55
  56 static unsigned long
  57 nilfs_cpfile_checkpoints_in_block(const struct inode *cpfile,
  58                                   __u64 curr,
  59                                   __u64 max)
  60 {
  61         return min_t(__u64,
  62                      nilfs_cpfile_checkpoints_per_block(cpfile) -
  63                      nilfs_cpfile_get_offset(cpfile, curr),
  64                      max - curr);
  65 }
  66
  67 static inline int nilfs_cpfile_is_in_first(const struct inode *cpfile,
  68                                            __u64 cno)
  69 {
  70         return nilfs_cpfile_get_blkoff(cpfile, cno) == 0;
  71 }
  72
  73 static unsigned int
  74 nilfs_cpfile_block_add_valid_checkpoints(const struct inode *cpfile,
  75                                          struct buffer_head *bh,
  76                                          void *kaddr,
  77                                          unsigned int n)
  78 {
  79         struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
  80         unsigned int count;
  81
  82         count = le32_to_cpu(cp->cp_checkpoints_count) + n;
  83         cp->cp_checkpoints_count = cpu_to_le32(count);
  84         return count;
  85 }
  86
  87 static unsigned int
  88 nilfs_cpfile_block_sub_valid_checkpoints(const struct inode *cpfile,
  89                                          struct buffer_head *bh,
  90                                          void *kaddr,
  91                                          unsigned int n)
  92 {
  93         struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
  94         unsigned int count;
  95
  96         WARN_ON(le32_to_cpu(cp->cp_checkpoints_count) < n);
  97         count = le32_to_cpu(cp->cp_checkpoints_count) - n;
  98         cp->cp_checkpoints_count = cpu_to_le32(count);
  99         return count;
 100 }
 101
 102 static inline struct nilfs_cpfile_header *
 103 nilfs_cpfile_block_get_header(const struct inode *cpfile,
 104                               struct buffer_head *bh,
 105                               void *kaddr)
 106 {
 107         return kaddr + bh_offset(bh);
 108 }
 109
 110 static struct nilfs_checkpoint *
 111 nilfs_cpfile_block_get_checkpoint(const struct inode *cpfile, __u64 cno,
 112                                   struct buffer_head *bh,
 113                                   void *kaddr)
 114 {
 115         return kaddr + bh_offset(bh) + nilfs_cpfile_get_offset(cpfile, cno) *
 116                 NILFS_MDT(cpfile)->mi_entry_size;
 117 }
 118
 119 static void nilfs_cpfile_block_init(struct inode *cpfile,
 120                                     struct buffer_head *bh,
 121                                     void *kaddr)
 122 {
 123         struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
 124         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 125         int n = nilfs_cpfile_checkpoints_per_block(cpfile);
 126
 127         while (n-- > 0) {
 128                 nilfs_checkpoint_set_invalid(cp);
 129                 cp = (void *)cp + cpsz;
 130         }
 131 }
 132
 133 static inline int nilfs_cpfile_get_header_block(struct inode *cpfile,
 134                                                 struct buffer_head **bhp)
 135 {
 136         return nilfs_mdt_get_block(cpfile, 0, 0, NULL, bhp);
 137 }
 138
 139 static inline int nilfs_cpfile_get_checkpoint_block(struct inode *cpfile,
 140                                                     __u64 cno,
 141                                                     int create,
 142                                                     struct buffer_head **bhp)
 143 {
 144         return nilfs_mdt_get_block(cpfile,
 145                                    nilfs_cpfile_get_blkoff(cpfile, cno),
 146                                    create, nilfs_cpfile_block_init, bhp);
 147 }
 148
 149 static inline int nilfs_cpfile_delete_checkpoint_block(struct inode *cpfile,
 150                                                        __u64 cno)
 151 {
 152         return nilfs_mdt_delete_block(cpfile,
 153                                       nilfs_cpfile_get_blkoff(cpfile, cno));
 154 }
 155
 156 /**
 157  * nilfs_cpfile_get_checkpoint - get a checkpoint
 158  * @cpfile: inode of checkpoint file
 159  * @cno: checkpoint number
 160  * @create: create flag
 161  * @cpp: pointer to a checkpoint
 162  * @bhp: pointer to a buffer head
 163  *
 164  * Description: nilfs_cpfile_get_checkpoint() acquires the checkpoint
 165  * specified by @cno. A new checkpoint will be created if @cno is the current
 166  * checkpoint number and @create is nonzero.
 167  *
 168  * Return Value: On success, 0 is returned, and the checkpoint and the
 169  * buffer head of the buffer on which the checkpoint is located are stored in
 170  * the place pointed by @cpp and @bhp, respectively. On error, one of the
 171  * following negative error codes is returned.
 172  *
 173  * %-EIO - I/O error.
 174  *
 175  * %-ENOMEM - Insufficient amount of memory available.
 176  *
 177  * %-ENOENT - No such checkpoint.
 178  *
 179  * %-EINVAL - invalid checkpoint.
 180  */
 181 int nilfs_cpfile_get_checkpoint(struct inode *cpfile,
 182                                 __u64 cno,
 183                                 int create,
 184                                 struct nilfs_checkpoint **cpp,
 185                                 struct buffer_head **bhp)
 186 {
 187         struct buffer_head *header_bh, *cp_bh;
 188         struct nilfs_cpfile_header *header;
 189         struct nilfs_checkpoint *cp;
 190         void *kaddr;
 191         int ret;
 192
 193         if (unlikely(cno < 1 || cno > nilfs_mdt_cno(cpfile) ||
 194                      (cno < nilfs_mdt_cno(cpfile) && create)))
 195                 return -EINVAL;
 196
 197         down_write(&NILFS_MDT(cpfile)->mi_sem);
 198
 199         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 200         if (ret < 0)
 201                 goto out_sem;
 202         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, create, &cp_bh);
 203         if (ret < 0)
 204                 goto out_header;
 205         kaddr = kmap(cp_bh->b_page);
 206         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 207         if (nilfs_checkpoint_invalid(cp)) {
 208                 if (!create) {
 209                         kunmap(cp_bh->b_page);
 210                         brelse(cp_bh);
 211                         ret = -ENOENT;
 212                         goto out_header;
 213                 }
 214                 /* a newly-created checkpoint */
 215                 nilfs_checkpoint_clear_invalid(cp);
 216                 if (!nilfs_cpfile_is_in_first(cpfile, cno))
 217                         nilfs_cpfile_block_add_valid_checkpoints(cpfile, cp_bh,
 218                                                                  kaddr, 1);
 219                 mark_buffer_dirty(cp_bh);
 220
 221                 kaddr = kmap_atomic(header_bh->b_page);
 222                 header = nilfs_cpfile_block_get_header(cpfile, header_bh,
 223                                                        kaddr);
 224                 le64_add_cpu(&header->ch_ncheckpoints, 1);
 225                 kunmap_atomic(kaddr);
 226                 mark_buffer_dirty(header_bh);
 227                 nilfs_mdt_mark_dirty(cpfile);
 228         }
 229
 230         if (cpp != NULL)
 231                 *cpp = cp;
 232         *bhp = cp_bh;
 233
 234  out_header:
 235         brelse(header_bh);
 236
 237  out_sem:
 238         up_write(&NILFS_MDT(cpfile)->mi_sem);
 239         return ret;
 240 }
 241
 242 /**
 243  * nilfs_cpfile_put_checkpoint - put a checkpoint
 244  * @cpfile: inode of checkpoint file
 245  * @cno: checkpoint number
 246  * @bh: buffer head
 247  *
 248  * Description: nilfs_cpfile_put_checkpoint() releases the checkpoint
 249  * specified by @cno. @bh must be the buffer head which has been returned by
 250  * a previous call to nilfs_cpfile_get_checkpoint() with @cno.
 251  */
 252 void nilfs_cpfile_put_checkpoint(struct inode *cpfile, __u64 cno,
 253                                  struct buffer_head *bh)
 254 {
 255         kunmap(bh->b_page);
 256         brelse(bh);
 257 }
 258
 259 /**
 260  * nilfs_cpfile_delete_checkpoints - delete checkpoints
 261  * @cpfile: inode of checkpoint file
 262  * @start: start checkpoint number
 263  * @end: end checkpoint numer
 264  *
 265  * Description: nilfs_cpfile_delete_checkpoints() deletes the checkpoints in
 266  * the period from @start to @end, excluding @end itself. The checkpoints
 267  * which have been already deleted are ignored.
 268  *
 269  * Return Value: On success, 0 is returned. On error, one of the following
 270  * negative error codes is returned.
 271  *
 272  * %-EIO - I/O error.
 273  *
 274  * %-ENOMEM - Insufficient amount of memory available.
 275  *
 276  * %-EINVAL - invalid checkpoints.
 277  */
 278 int nilfs_cpfile_delete_checkpoints(struct inode *cpfile,
 279                                     __u64 start,
 280                                     __u64 end)
 281 {
 282         struct buffer_head *header_bh, *cp_bh;
 283         struct nilfs_cpfile_header *header;
 284         struct nilfs_checkpoint *cp;
 285         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 286         __u64 cno;
 287         void *kaddr;
 288         unsigned long tnicps;
 289         int ret, ncps, nicps, nss, count, i;
 290
 291         if (unlikely(start == 0 || start > end)) {
 292                 printk(KERN_ERR "%s: invalid range of checkpoint numbers: "
 293                        "[%llu, %llu)\n", __func__,
 294                        (unsigned long long)start, (unsigned long long)end);
 295                 return -EINVAL;
 296         }
 297
 298         down_write(&NILFS_MDT(cpfile)->mi_sem);
 299
 300         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 301         if (ret < 0)
 302                 goto out_sem;
 303         tnicps = 0;
 304         nss = 0;
 305
 306         for (cno = start; cno < end; cno += ncps) {
 307                 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, end);
 308                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 309                 if (ret < 0) {
 310                         if (ret != -ENOENT)
 311                                 break;
 312                         /* skip hole */
 313                         ret = 0;
 314                         continue;
 315                 }
 316
 317                 kaddr = kmap_atomic(cp_bh->b_page);
 318                 cp = nilfs_cpfile_block_get_checkpoint(
 319                         cpfile, cno, cp_bh, kaddr);
 320                 nicps = 0;
 321                 for (i = 0; i < ncps; i++, cp = (void *)cp + cpsz) {
 322                         if (nilfs_checkpoint_snapshot(cp)) {
 323                                 nss++;
 324                         } else if (!nilfs_checkpoint_invalid(cp)) {
 325                                 nilfs_checkpoint_set_invalid(cp);
 326                                 nicps++;
 327                         }
 328                 }
 329                 if (nicps > 0) {
 330                         tnicps += nicps;
 331                         mark_buffer_dirty(cp_bh);
 332                         nilfs_mdt_mark_dirty(cpfile);
 333                         if (!nilfs_cpfile_is_in_first(cpfile, cno)) {
 334                                 count =
 335                                   nilfs_cpfile_block_sub_valid_checkpoints(
 336                                                 cpfile, cp_bh, kaddr, nicps);
 337                                 if (count == 0) {
 338                                         /* make hole */
 339                                         kunmap_atomic(kaddr);
 340                                         brelse(cp_bh);
 341                                         ret =
 342                                           nilfs_cpfile_delete_checkpoint_block(
 343                                                                    cpfile, cno);
 344                                         if (ret == 0)
 345                                                 continue;
 346                                         printk(KERN_ERR
 347                                                "%s: cannot delete block\n",
 348                                                __func__);
 349                                         break;
 350                                 }
 351                         }
 352                 }
 353
 354                 kunmap_atomic(kaddr);
 355                 brelse(cp_bh);
 356         }
 357
 358         if (tnicps > 0) {
 359                 kaddr = kmap_atomic(header_bh->b_page);
 360                 header = nilfs_cpfile_block_get_header(cpfile, header_bh,
 361                                                        kaddr);
 362                 le64_add_cpu(&header->ch_ncheckpoints, -(u64)tnicps);
 363                 mark_buffer_dirty(header_bh);
 364                 nilfs_mdt_mark_dirty(cpfile);
 365                 kunmap_atomic(kaddr);
 366         }
 367
 368         brelse(header_bh);
 369         if (nss > 0)
 370                 ret = -EBUSY;
 371
 372  out_sem:
 373         up_write(&NILFS_MDT(cpfile)->mi_sem);
 374         return ret;
 375 }
 376
 377 static void nilfs_cpfile_checkpoint_to_cpinfo(struct inode *cpfile,
 378                                               struct nilfs_checkpoint *cp,
 379                                               struct nilfs_cpinfo *ci)
 380 {
 381         ci->ci_flags = le32_to_cpu(cp->cp_flags);
 382         ci->ci_cno = le64_to_cpu(cp->cp_cno);
 383         ci->ci_create = le64_to_cpu(cp->cp_create);
 384         ci->ci_nblk_inc = le64_to_cpu(cp->cp_nblk_inc);
 385         ci->ci_inodes_count = le64_to_cpu(cp->cp_inodes_count);
 386         ci->ci_blocks_count = le64_to_cpu(cp->cp_blocks_count);
 387         ci->ci_next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
 388 }
 389
 390 static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
 391                                           void *buf, unsigned cisz, size_t nci)
 392 {
 393         struct nilfs_checkpoint *cp;
 394         struct nilfs_cpinfo *ci = buf;
 395         struct buffer_head *bh;
 396         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 397         __u64 cur_cno = nilfs_mdt_cno(cpfile), cno = *cnop;
 398         void *kaddr;
 399         int n, ret;
 400         int ncps, i;
 401
 402         if (cno == 0)
 403                 return -ENOENT; /* checkpoint number 0 is invalid */
 404         down_read(&NILFS_MDT(cpfile)->mi_sem);
 405
 406         for (n = 0; cno < cur_cno && n < nci; cno += ncps) {
 407                 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
 408                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
 409                 if (ret < 0) {
 410                         if (ret != -ENOENT)
 411                                 goto out;
 412                         continue; /* skip hole */
 413                 }
 414
 415                 kaddr = kmap_atomic(bh->b_page);
 416                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 417                 for (i = 0; i < ncps && n < nci; i++, cp = (void *)cp + cpsz) {
 418                         if (!nilfs_checkpoint_invalid(cp)) {
 419                                 nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp,
 420                                                                   ci);
 421                                 ci = (void *)ci + cisz;
 422                                 n++;
 423                         }
 424                 }
 425                 kunmap_atomic(kaddr);
 426                 brelse(bh);
 427         }
 428
 429         ret = n;
 430         if (n > 0) {
 431                 ci = (void *)ci - cisz;
 432                 *cnop = ci->ci_cno + 1;
 433         }
 434
 435  out:
 436         up_read(&NILFS_MDT(cpfile)->mi_sem);
 437         return ret;
 438 }
 439
 440 static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
 441                                           void *buf, unsigned cisz, size_t nci)
 442 {
 443         struct buffer_head *bh;
 444         struct nilfs_cpfile_header *header;
 445         struct nilfs_checkpoint *cp;
 446         struct nilfs_cpinfo *ci = buf;
 447         __u64 curr = *cnop, next;
 448         unsigned long curr_blkoff, next_blkoff;
 449         void *kaddr;
 450         int n = 0, ret;
 451
 452         down_read(&NILFS_MDT(cpfile)->mi_sem);
 453
 454         if (curr == 0) {
 455                 ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 456                 if (ret < 0)
 457                         goto out;
 458                 kaddr = kmap_atomic(bh->b_page);
 459                 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 460                 curr = le64_to_cpu(header->ch_snapshot_list.ssl_next);
 461                 kunmap_atomic(kaddr);
 462                 brelse(bh);
 463                 if (curr == 0) {
 464                         ret = 0;
 465                         goto out;
 466                 }
 467         } else if (unlikely(curr == ~(__u64)0)) {
 468                 ret = 0;
 469                 goto out;
 470         }
 471
 472         curr_blkoff = nilfs_cpfile_get_blkoff(cpfile, curr);
 473         ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr, 0, &bh);
 474         if (unlikely(ret < 0)) {
 475                 if (ret == -ENOENT)
 476                         ret = 0; /* No snapshots (started from a hole block) */
 477                 goto out;
 478         }
 479         kaddr = kmap_atomic(bh->b_page);
 480         while (n < nci) {
 481                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, curr, bh, kaddr);
 482                 curr = ~(__u64)0; /* Terminator */
 483                 if (unlikely(nilfs_checkpoint_invalid(cp) ||
 484                              !nilfs_checkpoint_snapshot(cp)))
 485                         break;
 486                 nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp, ci);
 487                 ci = (void *)ci + cisz;
 488                 n++;
 489                 next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
 490                 if (next == 0)
 491                         break; /* reach end of the snapshot list */
 492
 493                 next_blkoff = nilfs_cpfile_get_blkoff(cpfile, next);
 494                 if (curr_blkoff != next_blkoff) {
 495                         kunmap_atomic(kaddr);
 496                         brelse(bh);
 497                         ret = nilfs_cpfile_get_checkpoint_block(cpfile, next,
 498                                                                 0, &bh);
 499                         if (unlikely(ret < 0)) {
 500                                 WARN_ON(ret == -ENOENT);
 501                                 goto out;
 502                         }
 503                         kaddr = kmap_atomic(bh->b_page);
 504                 }
 505                 curr = next;
 506                 curr_blkoff = next_blkoff;
 507         }
 508         kunmap_atomic(kaddr);
 509         brelse(bh);
 510         *cnop = curr;
 511         ret = n;
 512
 513  out:
 514         up_read(&NILFS_MDT(cpfile)->mi_sem);
 515         return ret;
 516 }
 517
 518 /**
 519  * nilfs_cpfile_get_cpinfo -
 520  * @cpfile:
 521  * @cno:
 522  * @ci:
 523  * @nci:
 524  */
 525
 526 ssize_t nilfs_cpfile_get_cpinfo(struct inode *cpfile, __u64 *cnop, int mode,
 527                                 void *buf, unsigned cisz, size_t nci)
 528 {
 529         switch (mode) {
 530         case NILFS_CHECKPOINT:
 531                 return nilfs_cpfile_do_get_cpinfo(cpfile, cnop, buf, cisz, nci);
 532         case NILFS_SNAPSHOT:
 533                 return nilfs_cpfile_do_get_ssinfo(cpfile, cnop, buf, cisz, nci);
 534         default:
 535                 return -EINVAL;
 536         }
 537 }
 538
 539 /**
 540  * nilfs_cpfile_delete_checkpoint -
 541  * @cpfile:
 542  * @cno:
 543  */
 544 int nilfs_cpfile_delete_checkpoint(struct inode *cpfile, __u64 cno)
 545 {
 546         struct nilfs_cpinfo ci;
 547         __u64 tcno = cno;
 548         ssize_t nci;
 549
 550         nci = nilfs_cpfile_do_get_cpinfo(cpfile, &tcno, &ci, sizeof(ci), 1);
 551         if (nci < 0)
 552                 return nci;
 553         else if (nci == 0 || ci.ci_cno != cno)
 554                 return -ENOENT;
 555         else if (nilfs_cpinfo_snapshot(&ci))
 556                 return -EBUSY;
 557
 558         return nilfs_cpfile_delete_checkpoints(cpfile, cno, cno + 1);
 559 }
 560
 561 static struct nilfs_snapshot_list *
 562 nilfs_cpfile_block_get_snapshot_list(const struct inode *cpfile,
 563                                      __u64 cno,
 564                                      struct buffer_head *bh,
 565                                      void *kaddr)
 566 {
 567         struct nilfs_cpfile_header *header;
 568         struct nilfs_checkpoint *cp;
 569         struct nilfs_snapshot_list *list;
 570
 571         if (cno != 0) {
 572                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 573                 list = &cp->cp_snapshot_list;
 574         } else {
 575                 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 576                 list = &header->ch_snapshot_list;
 577         }
 578         return list;
 579 }
 580
 581 static int nilfs_cpfile_set_snapshot(struct inode *cpfile, __u64 cno)
 582 {
 583         struct buffer_head *header_bh, *curr_bh, *prev_bh, *cp_bh;
 584         struct nilfs_cpfile_header *header;
 585         struct nilfs_checkpoint *cp;
 586         struct nilfs_snapshot_list *list;
 587         __u64 curr, prev;
 588         unsigned long curr_blkoff, prev_blkoff;
 589         void *kaddr;
 590         int ret;
 591
 592         if (cno == 0)
 593                 return -ENOENT; /* checkpoint number 0 is invalid */
 594         down_write(&NILFS_MDT(cpfile)->mi_sem);
 595
 596         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 597         if (ret < 0)
 598                 goto out_sem;
 599         kaddr = kmap_atomic(cp_bh->b_page);
 600         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 601         if (nilfs_checkpoint_invalid(cp)) {
 602                 ret = -ENOENT;
 603                 kunmap_atomic(kaddr);
 604                 goto out_cp;
 605         }
 606         if (nilfs_checkpoint_snapshot(cp)) {
 607                 ret = 0;
 608                 kunmap_atomic(kaddr);
 609                 goto out_cp;
 610         }
 611         kunmap_atomic(kaddr);
 612
 613         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 614         if (ret < 0)
 615                 goto out_cp;
 616         kaddr = kmap_atomic(header_bh->b_page);
 617         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 618         list = &header->ch_snapshot_list;
 619         curr_bh = header_bh;
 620         get_bh(curr_bh);
 621         curr = 0;
 622         curr_blkoff = 0;
 623         prev = le64_to_cpu(list->ssl_prev);
 624         while (prev > cno) {
 625                 prev_blkoff = nilfs_cpfile_get_blkoff(cpfile, prev);
 626                 curr = prev;
 627                 if (curr_blkoff != prev_blkoff) {
 628                         kunmap_atomic(kaddr);
 629                         brelse(curr_bh);
 630                         ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr,
 631                                                                 0, &curr_bh);
 632                         if (ret < 0)
 633                                 goto out_header;
 634                         kaddr = kmap_atomic(curr_bh->b_page);
 635                 }
 636                 curr_blkoff = prev_blkoff;
 637                 cp = nilfs_cpfile_block_get_checkpoint(
 638                         cpfile, curr, curr_bh, kaddr);
 639                 list = &cp->cp_snapshot_list;
 640                 prev = le64_to_cpu(list->ssl_prev);
 641         }
 642         kunmap_atomic(kaddr);
 643
 644         if (prev != 0) {
 645                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 646                                                         &prev_bh);
 647                 if (ret < 0)
 648                         goto out_curr;
 649         } else {
 650                 prev_bh = header_bh;
 651                 get_bh(prev_bh);
 652         }
 653
 654         kaddr = kmap_atomic(curr_bh->b_page);
 655         list = nilfs_cpfile_block_get_snapshot_list(
 656                 cpfile, curr, curr_bh, kaddr);
 657         list->ssl_prev = cpu_to_le64(cno);
 658         kunmap_atomic(kaddr);
 659
 660         kaddr = kmap_atomic(cp_bh->b_page);
 661         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 662         cp->cp_snapshot_list.ssl_next = cpu_to_le64(curr);
 663         cp->cp_snapshot_list.ssl_prev = cpu_to_le64(prev);
 664         nilfs_checkpoint_set_snapshot(cp);
 665         kunmap_atomic(kaddr);
 666
 667         kaddr = kmap_atomic(prev_bh->b_page);
 668         list = nilfs_cpfile_block_get_snapshot_list(
 669                 cpfile, prev, prev_bh, kaddr);
 670         list->ssl_next = cpu_to_le64(cno);
 671         kunmap_atomic(kaddr);
 672
 673         kaddr = kmap_atomic(header_bh->b_page);
 674         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 675         le64_add_cpu(&header->ch_nsnapshots, 1);
 676         kunmap_atomic(kaddr);
 677
 678         mark_buffer_dirty(prev_bh);
 679         mark_buffer_dirty(curr_bh);
 680         mark_buffer_dirty(cp_bh);
 681         mark_buffer_dirty(header_bh);
 682         nilfs_mdt_mark_dirty(cpfile);
 683
 684         brelse(prev_bh);
 685
 686  out_curr:
 687         brelse(curr_bh);
 688
 689  out_header:
 690         brelse(header_bh);
 691
 692  out_cp:
 693         brelse(cp_bh);
 694
 695  out_sem:
 696         up_write(&NILFS_MDT(cpfile)->mi_sem);
 697         return ret;
 698 }
 699
 700 static int nilfs_cpfile_clear_snapshot(struct inode *cpfile, __u64 cno)
 701 {
 702         struct buffer_head *header_bh, *next_bh, *prev_bh, *cp_bh;
 703         struct nilfs_cpfile_header *header;
 704         struct nilfs_checkpoint *cp;
 705         struct nilfs_snapshot_list *list;
 706         __u64 next, prev;
 707         void *kaddr;
 708         int ret;
 709
 710         if (cno == 0)
 711                 return -ENOENT; /* checkpoint number 0 is invalid */
 712         down_write(&NILFS_MDT(cpfile)->mi_sem);
 713
 714         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 715         if (ret < 0)
 716                 goto out_sem;
 717         kaddr = kmap_atomic(cp_bh->b_page);
 718         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 719         if (nilfs_checkpoint_invalid(cp)) {
 720                 ret = -ENOENT;
 721                 kunmap_atomic(kaddr);
 722                 goto out_cp;
 723         }
 724         if (!nilfs_checkpoint_snapshot(cp)) {
 725                 ret = 0;
 726                 kunmap_atomic(kaddr);
 727                 goto out_cp;
 728         }
 729
 730         list = &cp->cp_snapshot_list;
 731         next = le64_to_cpu(list->ssl_next);
 732         prev = le64_to_cpu(list->ssl_prev);
 733         kunmap_atomic(kaddr);
 734
 735         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 736         if (ret < 0)
 737                 goto out_cp;
 738         if (next != 0) {
 739                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, next, 0,
 740                                                         &next_bh);
 741                 if (ret < 0)
 742                         goto out_header;
 743         } else {
 744                 next_bh = header_bh;
 745                 get_bh(next_bh);
 746         }
 747         if (prev != 0) {
 748                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 749                                                         &prev_bh);
 750                 if (ret < 0)
 751                         goto out_next;
 752         } else {
 753                 prev_bh = header_bh;
 754                 get_bh(prev_bh);
 755         }
 756
 757         kaddr = kmap_atomic(next_bh->b_page);
 758         list = nilfs_cpfile_block_get_snapshot_list(
 759                 cpfile, next, next_bh, kaddr);
 760         list->ssl_prev = cpu_to_le64(prev);
 761         kunmap_atomic(kaddr);
 762
 763         kaddr = kmap_atomic(prev_bh->b_page);
 764         list = nilfs_cpfile_block_get_snapshot_list(
 765                 cpfile, prev, prev_bh, kaddr);
 766         list->ssl_next = cpu_to_le64(next);
 767         kunmap_atomic(kaddr);
 768
 769         kaddr = kmap_atomic(cp_bh->b_page);
 770         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 771         cp->cp_snapshot_list.ssl_next = cpu_to_le64(0);
 772         cp->cp_snapshot_list.ssl_prev = cpu_to_le64(0);
 773         nilfs_checkpoint_clear_snapshot(cp);
 774         kunmap_atomic(kaddr);
 775
 776         kaddr = kmap_atomic(header_bh->b_page);
 777         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 778         le64_add_cpu(&header->ch_nsnapshots, -1);
 779         kunmap_atomic(kaddr);
 780
 781         mark_buffer_dirty(next_bh);
 782         mark_buffer_dirty(prev_bh);
 783         mark_buffer_dirty(cp_bh);
 784         mark_buffer_dirty(header_bh);
 785         nilfs_mdt_mark_dirty(cpfile);
 786
 787         brelse(prev_bh);
 788
 789  out_next:
 790         brelse(next_bh);
 791
 792  out_header:
 793         brelse(header_bh);
 794
 795  out_cp:
 796         brelse(cp_bh);
 797
 798  out_sem:
 799         up_write(&NILFS_MDT(cpfile)->mi_sem);
 800         return ret;
 801 }
 802
 803 /**
 804  * nilfs_cpfile_is_snapshot -
 805  * @cpfile: inode of checkpoint file
 806  * @cno: checkpoint number
 807  *
 808  * Description:
 809  *
 810  * Return Value: On success, 1 is returned if the checkpoint specified by
 811  * @cno is a snapshot, or 0 if not. On error, one of the following negative
 812  * error codes is returned.
 813  *
 814  * %-EIO - I/O error.
 815  *
 816  * %-ENOMEM - Insufficient amount of memory available.
 817  *
 818  * %-ENOENT - No such checkpoint.
 819  */
 820 int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
 821 {
 822         struct buffer_head *bh;
 823         struct nilfs_checkpoint *cp;
 824         void *kaddr;
 825         int ret;
 826
 827         /* CP number is invalid if it's zero or larger than the
 828         largest exist one.*/
 829         if (cno == 0 || cno >= nilfs_mdt_cno(cpfile))
 830                 return -ENOENT;
 831         down_read(&NILFS_MDT(cpfile)->mi_sem);
 832
 833         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
 834         if (ret < 0)
 835                 goto out;
 836         kaddr = kmap_atomic(bh->b_page);
 837         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 838         if (nilfs_checkpoint_invalid(cp))
 839                 ret = -ENOENT;
 840         else
 841                 ret = nilfs_checkpoint_snapshot(cp);
 842         kunmap_atomic(kaddr);
 843         brelse(bh);
 844
 845  out:
 846         up_read(&NILFS_MDT(cpfile)->mi_sem);
 847         return ret;
 848 }
 849
 850 /**
 851  * nilfs_cpfile_change_cpmode - change checkpoint mode
 852  * @cpfile: inode of checkpoint file
 853  * @cno: checkpoint number
 854  * @status: mode of checkpoint
 855  *
 856  * Description: nilfs_change_cpmode() changes the mode of the checkpoint
 857  * specified by @cno. The mode @mode is NILFS_CHECKPOINT or NILFS_SNAPSHOT.
 858  *
 859  * Return Value: On success, 0 is returned. On error, one of the following
 860  * negative error codes is returned.
 861  *
 862  * %-EIO - I/O error.
 863  *
 864  * %-ENOMEM - Insufficient amount of memory available.
 865  *
 866  * %-ENOENT - No such checkpoint.
 867  */
 868 int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
 869 {
 870         int ret;
 871
 872         switch (mode) {
 873         case NILFS_CHECKPOINT:
 874                 if (nilfs_checkpoint_is_mounted(cpfile->i_sb, cno))
 875                         /*
 876                          * Current implementation does not have to protect
 877                          * plain read-only mounts since they are exclusive
 878                          * with a read/write mount and are protected from the
 879                          * cleaner.
 880                          */
 881                         ret = -EBUSY;
 882                 else
 883                         ret = nilfs_cpfile_clear_snapshot(cpfile, cno);
 884                 return ret;
 885         case NILFS_SNAPSHOT:
 886                 return nilfs_cpfile_set_snapshot(cpfile, cno);
 887         default:
 888                 return -EINVAL;
 889         }
 890 }
 891
 892 /**
 893  * nilfs_cpfile_get_stat - get checkpoint statistics
 894  * @cpfile: inode of checkpoint file
 895  * @stat: pointer to a structure of checkpoint statistics
 896  *
 897  * Description: nilfs_cpfile_get_stat() returns information about checkpoints.
 898  *
 899  * Return Value: On success, 0 is returned, and checkpoints information is
 900  * stored in the place pointed by @stat. On error, one of the following
 901  * negative error codes is returned.
 902  *
 903  * %-EIO - I/O error.
 904  *
 905  * %-ENOMEM - Insufficient amount of memory available.
 906  */
 907 int nilfs_cpfile_get_stat(struct inode *cpfile, struct nilfs_cpstat *cpstat)
 908 {
 909         struct buffer_head *bh;
 910         struct nilfs_cpfile_header *header;
 911         void *kaddr;
 912         int ret;
 913
 914         down_read(&NILFS_MDT(cpfile)->mi_sem);
 915
 916         ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 917         if (ret < 0)
 918                 goto out_sem;
 919         kaddr = kmap_atomic(bh->b_page);
 920         header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 921         cpstat->cs_cno = nilfs_mdt_cno(cpfile);
 922         cpstat->cs_ncps = le64_to_cpu(header->ch_ncheckpoints);
 923         cpstat->cs_nsss = le64_to_cpu(header->ch_nsnapshots);
 924         kunmap_atomic(kaddr);
 925         brelse(bh);
 926
 927  out_sem:
 928         up_read(&NILFS_MDT(cpfile)->mi_sem);
 929         return ret;
 930 }
 931
 932 /**
 933  * nilfs_cpfile_read - read or get cpfile inode
 934  * @sb: super block instance
 935  * @cpsize: size of a checkpoint entry
 936  * @raw_inode: on-disk cpfile inode
 937  * @inodep: buffer to store the inode
 938  */
 939 int nilfs_cpfile_read(struct super_block *sb, size_t cpsize,
 940                       struct nilfs_inode *raw_inode, struct inode **inodep)
 941 {
 942         struct inode *cpfile;
 943         int err;
 944
 945         cpfile = nilfs_iget_locked(sb, NULL, NILFS_CPFILE_INO);
 946         if (unlikely(!cpfile))
 947                 return -ENOMEM;
 948         if (!(cpfile->i_state & I_NEW))
 949                 goto out;
 950
 951         err = nilfs_mdt_init(cpfile, NILFS_MDT_GFP, 0);
 952         if (err)
 953                 goto failed;
 954
 955         nilfs_mdt_set_entry_size(cpfile, cpsize,
 956                                  sizeof(struct nilfs_cpfile_header));
 957
 958         err = nilfs_read_inode_common(cpfile, raw_inode);
 959         if (err)
 960                 goto failed;
 961
 962         unlock_new_inode(cpfile);
 963  out:
 964         *inodep = cpfile;
 965         return 0;
 966  failed:
 967         iget_failed(cpfile);
 968         return err;
 969 }