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 <koji@osrg.net>.
  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;
  44
  45         BUG_ON(cno == 0); /* checkpoint number 0 is invalid */
  46         tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
  47         do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
  48         return (unsigned long)tcno;
  49 }
  50
  51 /* offset in block */
  52 static unsigned long
  53 nilfs_cpfile_get_offset(const struct inode *cpfile, __u64 cno)
  54 {
  55         __u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
  56         return do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
  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         BUG_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 static inline int nilfs_cpfile_delete_checkpoint_block(struct inode *cpfile,
 153                                                        __u64 cno)
 154 {
 155         return nilfs_mdt_delete_block(cpfile,
 156                                       nilfs_cpfile_get_blkoff(cpfile, cno));
 157 }
 158
 159 /**
 160  * nilfs_cpfile_get_checkpoint - get a checkpoint
 161  * @cpfile: inode of checkpoint file
 162  * @cno: checkpoint number
 163  * @create: create flag
 164  * @cpp: pointer to a checkpoint
 165  * @bhp: pointer to a buffer head
 166  *
 167  * Description: nilfs_cpfile_get_checkpoint() acquires the checkpoint
 168  * specified by @cno. A new checkpoint will be created if @cno is the current
 169  * checkpoint number and @create is nonzero.
 170  *
 171  * Return Value: On success, 0 is returned, and the checkpoint and the
 172  * buffer head of the buffer on which the checkpoint is located are stored in
 173  * the place pointed by @cpp and @bhp, respectively. On error, one of the
 174  * following negative error codes is returned.
 175  *
 176  * %-EIO - I/O error.
 177  *
 178  * %-ENOMEM - Insufficient amount of memory available.
 179  *
 180  * %-ENOENT - No such checkpoint.
 181  */
 182 int nilfs_cpfile_get_checkpoint(struct inode *cpfile,
 183                                 __u64 cno,
 184                                 int create,
 185                                 struct nilfs_checkpoint **cpp,
 186                                 struct buffer_head **bhp)
 187 {
 188         struct buffer_head *header_bh, *cp_bh;
 189         struct nilfs_cpfile_header *header;
 190         struct nilfs_checkpoint *cp;
 191         void *kaddr;
 192         int ret;
 193
 194         BUG_ON(cno < 1 || cno > nilfs_mdt_cno(cpfile) ||
 195                (cno < nilfs_mdt_cno(cpfile) && create));
 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                 nilfs_mdt_mark_buffer_dirty(cp_bh);
 220
 221                 kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 222                 header = nilfs_cpfile_block_get_header(cpfile, header_bh,
 223                                                        kaddr);
 224                 le64_add_cpu(&header->ch_ncheckpoints, 1);
 225                 kunmap_atomic(kaddr, KM_USER0);
 226                 nilfs_mdt_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, count, i;
 290
 291         if ((start == 0) || (start > end)) {
 292                 printk(KERN_CRIT "%s: start = %llu, end = %llu\n",
 293                        __func__,
 294                        (unsigned long long)start,
 295                        (unsigned long long)end);
 296                 BUG();
 297         }
 298
 299         /* cannot delete the latest checkpoint */
 300         if (start == nilfs_mdt_cno(cpfile) - 1)
 301                 return -EPERM;
 302
 303         down_write(&NILFS_MDT(cpfile)->mi_sem);
 304
 305         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 306         if (ret < 0)
 307                 goto out_sem;
 308         tnicps = 0;
 309
 310         for (cno = start; cno < end; cno += ncps) {
 311                 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, end);
 312                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 313                 if (ret < 0) {
 314                         if (ret != -ENOENT)
 315                                 goto out_sem;
 316                         /* skip hole */
 317                         ret = 0;
 318                         continue;
 319                 }
 320
 321                 kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 322                 cp = nilfs_cpfile_block_get_checkpoint(
 323                         cpfile, cno, cp_bh, kaddr);
 324                 nicps = 0;
 325                 for (i = 0; i < ncps; i++, cp = (void *)cp + cpsz) {
 326                         BUG_ON(nilfs_checkpoint_snapshot(cp));
 327                         if (!nilfs_checkpoint_invalid(cp)) {
 328                                 nilfs_checkpoint_set_invalid(cp);
 329                                 nicps++;
 330                         }
 331                 }
 332                 if (nicps > 0) {
 333                         tnicps += nicps;
 334                         nilfs_mdt_mark_buffer_dirty(cp_bh);
 335                         nilfs_mdt_mark_dirty(cpfile);
 336                         if (!nilfs_cpfile_is_in_first(cpfile, cno) &&
 337                             (count = nilfs_cpfile_block_sub_valid_checkpoints(
 338                                     cpfile, cp_bh, kaddr, nicps)) == 0) {
 339                                 /* make hole */
 340                                 kunmap_atomic(kaddr, KM_USER0);
 341                                 brelse(cp_bh);
 342                                 ret = nilfs_cpfile_delete_checkpoint_block(
 343                                         cpfile, cno);
 344                                 if (ret == 0)
 345                                         continue;
 346                                 printk(KERN_ERR "%s: cannot delete block\n",
 347                                        __func__);
 348                                 goto out_sem;
 349                         }
 350                 }
 351
 352                 kunmap_atomic(kaddr, KM_USER0);
 353                 brelse(cp_bh);
 354         }
 355
 356         if (tnicps > 0) {
 357                 kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 358                 header = nilfs_cpfile_block_get_header(cpfile, header_bh,
 359                                                        kaddr);
 360                 le64_add_cpu(&header->ch_ncheckpoints, -(u64)tnicps);
 361                 nilfs_mdt_mark_buffer_dirty(header_bh);
 362                 nilfs_mdt_mark_dirty(cpfile);
 363                 kunmap_atomic(kaddr, KM_USER0);
 364         }
 365         brelse(header_bh);
 366
 367  out_sem:
 368         up_write(&NILFS_MDT(cpfile)->mi_sem);
 369         return ret;
 370 }
 371
 372 static void nilfs_cpfile_checkpoint_to_cpinfo(struct inode *cpfile,
 373                                               struct nilfs_checkpoint *cp,
 374                                               struct nilfs_cpinfo *ci)
 375 {
 376         ci->ci_flags = le32_to_cpu(cp->cp_flags);
 377         ci->ci_cno = le64_to_cpu(cp->cp_cno);
 378         ci->ci_create = le64_to_cpu(cp->cp_create);
 379         ci->ci_nblk_inc = le64_to_cpu(cp->cp_nblk_inc);
 380         ci->ci_inodes_count = le64_to_cpu(cp->cp_inodes_count);
 381         ci->ci_blocks_count = le64_to_cpu(cp->cp_blocks_count);
 382         ci->ci_next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
 383 }
 384
 385 static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
 386                                           struct nilfs_cpinfo *ci, size_t nci)
 387 {
 388         struct nilfs_checkpoint *cp;
 389         struct buffer_head *bh;
 390         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 391         __u64 cur_cno = nilfs_mdt_cno(cpfile), cno = *cnop;
 392         void *kaddr;
 393         int n, ret;
 394         int ncps, i;
 395
 396         down_read(&NILFS_MDT(cpfile)->mi_sem);
 397
 398         for (n = 0; cno < cur_cno && n < nci; cno += ncps) {
 399                 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
 400                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
 401                 if (ret < 0) {
 402                         if (ret != -ENOENT)
 403                                 goto out;
 404                         continue; /* skip hole */
 405                 }
 406
 407                 kaddr = kmap_atomic(bh->b_page, KM_USER0);
 408                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 409                 for (i = 0; i < ncps && n < nci; i++, cp = (void *)cp + cpsz) {
 410                         if (!nilfs_checkpoint_invalid(cp))
 411                                 nilfs_cpfile_checkpoint_to_cpinfo(
 412                                         cpfile, cp, &ci[n++]);
 413                 }
 414                 kunmap_atomic(kaddr, KM_USER0);
 415                 brelse(bh);
 416         }
 417
 418         ret = n;
 419         if (n > 0)
 420                 *cnop = ci[n - 1].ci_cno + 1;
 421
 422  out:
 423         up_read(&NILFS_MDT(cpfile)->mi_sem);
 424         return ret;
 425 }
 426
 427 static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
 428                                           struct nilfs_cpinfo *ci, size_t nci)
 429 {
 430         struct buffer_head *bh;
 431         struct nilfs_cpfile_header *header;
 432         struct nilfs_checkpoint *cp;
 433         __u64 curr = *cnop, next;
 434         unsigned long curr_blkoff, next_blkoff;
 435         void *kaddr;
 436         int n = 0, ret;
 437
 438         down_read(&NILFS_MDT(cpfile)->mi_sem);
 439
 440         if (curr == 0) {
 441                 ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 442                 if (ret < 0)
 443                         goto out;
 444                 kaddr = kmap_atomic(bh->b_page, KM_USER0);
 445                 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 446                 curr = le64_to_cpu(header->ch_snapshot_list.ssl_next);
 447                 kunmap_atomic(kaddr, KM_USER0);
 448                 brelse(bh);
 449                 if (curr == 0) {
 450                         ret = 0;
 451                         goto out;
 452                 }
 453         } else if (unlikely(curr == ~(__u64)0)) {
 454                 ret = 0;
 455                 goto out;
 456         }
 457
 458         curr_blkoff = nilfs_cpfile_get_blkoff(cpfile, curr);
 459         ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr, 0, &bh);
 460         if (unlikely(ret < 0)) {
 461                 if (ret == -ENOENT)
 462                         ret = 0; /* No snapshots (started from a hole block) */
 463                 goto out;
 464         }
 465         kaddr = kmap_atomic(bh->b_page, KM_USER0);
 466         while (n < nci) {
 467                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, curr, bh, kaddr);
 468                 curr = ~(__u64)0; /* Terminator */
 469                 if (unlikely(nilfs_checkpoint_invalid(cp) ||
 470                              !nilfs_checkpoint_snapshot(cp)))
 471                         break;
 472                 nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp, &ci[n++]);
 473                 next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
 474                 if (next == 0)
 475                         break; /* reach end of the snapshot list */
 476
 477                 next_blkoff = nilfs_cpfile_get_blkoff(cpfile, next);
 478                 if (curr_blkoff != next_blkoff) {
 479                         kunmap_atomic(kaddr, KM_USER0);
 480                         brelse(bh);
 481                         ret = nilfs_cpfile_get_checkpoint_block(cpfile, next,
 482                                                                 0, &bh);
 483                         if (unlikely(ret < 0)) {
 484                                 WARN_ON(ret == -ENOENT);
 485                                 goto out;
 486                         }
 487                         kaddr = kmap_atomic(bh->b_page, KM_USER0);
 488                 }
 489                 curr = next;
 490                 curr_blkoff = next_blkoff;
 491         }
 492         kunmap_atomic(kaddr, KM_USER0);
 493         brelse(bh);
 494         *cnop = curr;
 495         ret = n;
 496
 497  out:
 498         up_read(&NILFS_MDT(cpfile)->mi_sem);
 499         return ret;
 500 }
 501
 502 /**
 503  * nilfs_cpfile_get_cpinfo -
 504  * @cpfile:
 505  * @cno:
 506  * @ci:
 507  * @nci:
 508  */
 509
 510 ssize_t nilfs_cpfile_get_cpinfo(struct inode *cpfile, __u64 *cnop, int mode,
 511                                 struct nilfs_cpinfo *ci, size_t nci)
 512 {
 513         switch (mode) {
 514         case NILFS_CHECKPOINT:
 515                 return nilfs_cpfile_do_get_cpinfo(cpfile, cnop, ci, nci);
 516         case NILFS_SNAPSHOT:
 517                 return nilfs_cpfile_do_get_ssinfo(cpfile, cnop, ci, nci);
 518         default:
 519                 return -EINVAL;
 520         }
 521 }
 522
 523 /**
 524  * nilfs_cpfile_delete_checkpoint -
 525  * @cpfile:
 526  * @cno:
 527  */
 528 int nilfs_cpfile_delete_checkpoint(struct inode *cpfile, __u64 cno)
 529 {
 530         struct nilfs_cpinfo ci;
 531         __u64 tcno = cno;
 532         ssize_t nci;
 533         int ret;
 534
 535         /* checkpoint number 0 is invalid */
 536         if (cno == 0)
 537                 return -ENOENT;
 538         nci = nilfs_cpfile_do_get_cpinfo(cpfile, &tcno, &ci, 1);
 539         if (nci < 0)
 540                 return nci;
 541         else if (nci == 0 || ci.ci_cno != cno)
 542                 return -ENOENT;
 543
 544         /* cannot delete the latest checkpoint nor snapshots */
 545         ret = nilfs_cpinfo_snapshot(&ci);
 546         if (ret < 0)
 547                 return ret;
 548         else if (ret > 0 || cno == nilfs_mdt_cno(cpfile) - 1)
 549                 return -EPERM;
 550
 551         return nilfs_cpfile_delete_checkpoints(cpfile, cno, cno + 1);
 552 }
 553
 554 static struct nilfs_snapshot_list *
 555 nilfs_cpfile_block_get_snapshot_list(const struct inode *cpfile,
 556                                      __u64 cno,
 557                                      struct buffer_head *bh,
 558                                      void *kaddr)
 559 {
 560         struct nilfs_cpfile_header *header;
 561         struct nilfs_checkpoint *cp;
 562         struct nilfs_snapshot_list *list;
 563
 564         if (cno != 0) {
 565                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 566                 list = &cp->cp_snapshot_list;
 567         } else {
 568                 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 569                 list = &header->ch_snapshot_list;
 570         }
 571         return list;
 572 }
 573
 574 static int nilfs_cpfile_set_snapshot(struct inode *cpfile, __u64 cno)
 575 {
 576         struct buffer_head *header_bh, *curr_bh, *prev_bh, *cp_bh;
 577         struct nilfs_cpfile_header *header;
 578         struct nilfs_checkpoint *cp;
 579         struct nilfs_snapshot_list *list;
 580         __u64 curr, prev;
 581         unsigned long curr_blkoff, prev_blkoff;
 582         void *kaddr;
 583         int ret;
 584
 585         down_write(&NILFS_MDT(cpfile)->mi_sem);
 586
 587         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 588         if (ret < 0)
 589                 goto out_sem;
 590         kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 591         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 592         if (nilfs_checkpoint_invalid(cp)) {
 593                 ret = -ENOENT;
 594                 kunmap_atomic(kaddr, KM_USER0);
 595                 goto out_cp;
 596         }
 597         if (nilfs_checkpoint_snapshot(cp)) {
 598                 ret = 0;
 599                 kunmap_atomic(kaddr, KM_USER0);
 600                 goto out_cp;
 601         }
 602         kunmap_atomic(kaddr, KM_USER0);
 603
 604         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 605         if (ret < 0)
 606                 goto out_cp;
 607         kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 608         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 609         list = &header->ch_snapshot_list;
 610         curr_bh = header_bh;
 611         get_bh(curr_bh);
 612         curr = 0;
 613         curr_blkoff = 0;
 614         prev = le64_to_cpu(list->ssl_prev);
 615         while (prev > cno) {
 616                 prev_blkoff = nilfs_cpfile_get_blkoff(cpfile, prev);
 617                 curr = prev;
 618                 if (curr_blkoff != prev_blkoff) {
 619                         kunmap_atomic(kaddr, KM_USER0);
 620                         brelse(curr_bh);
 621                         ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr,
 622                                                                 0, &curr_bh);
 623                         if (ret < 0)
 624                                 goto out_header;
 625                         kaddr = kmap_atomic(curr_bh->b_page, KM_USER0);
 626                 }
 627                 curr_blkoff = prev_blkoff;
 628                 cp = nilfs_cpfile_block_get_checkpoint(
 629                         cpfile, curr, curr_bh, kaddr);
 630                 list = &cp->cp_snapshot_list;
 631                 prev = le64_to_cpu(list->ssl_prev);
 632         }
 633         kunmap_atomic(kaddr, KM_USER0);
 634
 635         if (prev != 0) {
 636                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 637                                                         &prev_bh);
 638                 if (ret < 0)
 639                         goto out_curr;
 640         } else {
 641                 prev_bh = header_bh;
 642                 get_bh(prev_bh);
 643         }
 644
 645         kaddr = kmap_atomic(curr_bh->b_page, KM_USER0);
 646         list = nilfs_cpfile_block_get_snapshot_list(
 647                 cpfile, curr, curr_bh, kaddr);
 648         list->ssl_prev = cpu_to_le64(cno);
 649         kunmap_atomic(kaddr, KM_USER0);
 650
 651         kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 652         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 653         cp->cp_snapshot_list.ssl_next = cpu_to_le64(curr);
 654         cp->cp_snapshot_list.ssl_prev = cpu_to_le64(prev);
 655         nilfs_checkpoint_set_snapshot(cp);
 656         kunmap_atomic(kaddr, KM_USER0);
 657
 658         kaddr = kmap_atomic(prev_bh->b_page, KM_USER0);
 659         list = nilfs_cpfile_block_get_snapshot_list(
 660                 cpfile, prev, prev_bh, kaddr);
 661         list->ssl_next = cpu_to_le64(cno);
 662         kunmap_atomic(kaddr, KM_USER0);
 663
 664         kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 665         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 666         le64_add_cpu(&header->ch_nsnapshots, 1);
 667         kunmap_atomic(kaddr, KM_USER0);
 668
 669         nilfs_mdt_mark_buffer_dirty(prev_bh);
 670         nilfs_mdt_mark_buffer_dirty(curr_bh);
 671         nilfs_mdt_mark_buffer_dirty(cp_bh);
 672         nilfs_mdt_mark_buffer_dirty(header_bh);
 673         nilfs_mdt_mark_dirty(cpfile);
 674
 675         brelse(prev_bh);
 676
 677  out_curr:
 678         brelse(curr_bh);
 679
 680  out_header:
 681         brelse(header_bh);
 682
 683  out_cp:
 684         brelse(cp_bh);
 685
 686  out_sem:
 687         up_write(&NILFS_MDT(cpfile)->mi_sem);
 688         return ret;
 689 }
 690
 691 static int nilfs_cpfile_clear_snapshot(struct inode *cpfile, __u64 cno)
 692 {
 693         struct buffer_head *header_bh, *next_bh, *prev_bh, *cp_bh;
 694         struct nilfs_cpfile_header *header;
 695         struct nilfs_checkpoint *cp;
 696         struct nilfs_snapshot_list *list;
 697         __u64 next, prev;
 698         void *kaddr;
 699         int ret;
 700
 701         down_write(&NILFS_MDT(cpfile)->mi_sem);
 702
 703         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 704         if (ret < 0)
 705                 goto out_sem;
 706         kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 707         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 708         if (nilfs_checkpoint_invalid(cp)) {
 709                 ret = -ENOENT;
 710                 kunmap_atomic(kaddr, KM_USER0);
 711                 goto out_cp;
 712         }
 713         if (!nilfs_checkpoint_snapshot(cp)) {
 714                 ret = 0;
 715                 kunmap_atomic(kaddr, KM_USER0);
 716                 goto out_cp;
 717         }
 718
 719         list = &cp->cp_snapshot_list;
 720         next = le64_to_cpu(list->ssl_next);
 721         prev = le64_to_cpu(list->ssl_prev);
 722         kunmap_atomic(kaddr, KM_USER0);
 723
 724         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 725         if (ret < 0)
 726                 goto out_cp;
 727         if (next != 0) {
 728                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, next, 0,
 729                                                         &next_bh);
 730                 if (ret < 0)
 731                         goto out_header;
 732         } else {
 733                 next_bh = header_bh;
 734                 get_bh(next_bh);
 735         }
 736         if (prev != 0) {
 737                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 738                                                         &prev_bh);
 739                 if (ret < 0)
 740                         goto out_next;
 741         } else {
 742                 prev_bh = header_bh;
 743                 get_bh(prev_bh);
 744         }
 745
 746         kaddr = kmap_atomic(next_bh->b_page, KM_USER0);
 747         list = nilfs_cpfile_block_get_snapshot_list(
 748                 cpfile, next, next_bh, kaddr);
 749         list->ssl_prev = cpu_to_le64(prev);
 750         kunmap_atomic(kaddr, KM_USER0);
 751
 752         kaddr = kmap_atomic(prev_bh->b_page, KM_USER0);
 753         list = nilfs_cpfile_block_get_snapshot_list(
 754                 cpfile, prev, prev_bh, kaddr);
 755         list->ssl_next = cpu_to_le64(next);
 756         kunmap_atomic(kaddr, KM_USER0);
 757
 758         kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 759         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 760         cp->cp_snapshot_list.ssl_next = cpu_to_le64(0);
 761         cp->cp_snapshot_list.ssl_prev = cpu_to_le64(0);
 762         nilfs_checkpoint_clear_snapshot(cp);
 763         kunmap_atomic(kaddr, KM_USER0);
 764
 765         kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 766         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 767         le64_add_cpu(&header->ch_nsnapshots, -1);
 768         kunmap_atomic(kaddr, KM_USER0);
 769
 770         nilfs_mdt_mark_buffer_dirty(next_bh);
 771         nilfs_mdt_mark_buffer_dirty(prev_bh);
 772         nilfs_mdt_mark_buffer_dirty(cp_bh);
 773         nilfs_mdt_mark_buffer_dirty(header_bh);
 774         nilfs_mdt_mark_dirty(cpfile);
 775
 776         brelse(prev_bh);
 777
 778  out_next:
 779         brelse(next_bh);
 780
 781  out_header:
 782         brelse(header_bh);
 783
 784  out_cp:
 785         brelse(cp_bh);
 786
 787  out_sem:
 788         up_write(&NILFS_MDT(cpfile)->mi_sem);
 789         return ret;
 790 }
 791
 792 /**
 793  * nilfs_cpfile_is_snapshot -
 794  * @cpfile: inode of checkpoint file
 795  * @cno: checkpoint number
 796  *
 797  * Description:
 798  *
 799  * Return Value: On success, 1 is returned if the checkpoint specified by
 800  * @cno is a snapshot, or 0 if not. On error, one of the following negative
 801  * error codes is returned.
 802  *
 803  * %-EIO - I/O error.
 804  *
 805  * %-ENOMEM - Insufficient amount of memory available.
 806  *
 807  * %-ENOENT - No such checkpoint.
 808  */
 809 int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
 810 {
 811         struct buffer_head *bh;
 812         struct nilfs_checkpoint *cp;
 813         void *kaddr;
 814         int ret;
 815
 816         down_read(&NILFS_MDT(cpfile)->mi_sem);
 817
 818         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
 819         if (ret < 0)
 820                 goto out;
 821         kaddr = kmap_atomic(bh->b_page, KM_USER0);
 822         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 823         ret = nilfs_checkpoint_snapshot(cp);
 824         kunmap_atomic(kaddr, KM_USER0);
 825         brelse(bh);
 826
 827  out:
 828         up_read(&NILFS_MDT(cpfile)->mi_sem);
 829         return ret;
 830 }
 831
 832 /**
 833  * nilfs_cpfile_change_cpmode - change checkpoint mode
 834  * @cpfile: inode of checkpoint file
 835  * @cno: checkpoint number
 836  * @status: mode of checkpoint
 837  *
 838  * Description: nilfs_change_cpmode() changes the mode of the checkpoint
 839  * specified by @cno. The mode @mode is NILFS_CHECKPOINT or NILFS_SNAPSHOT.
 840  *
 841  * Return Value: On success, 0 is returned. On error, one of the following
 842  * negative error codes is returned.
 843  *
 844  * %-EIO - I/O error.
 845  *
 846  * %-ENOMEM - Insufficient amount of memory available.
 847  *
 848  * %-ENOENT - No such checkpoint.
 849  */
 850 int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
 851 {
 852         struct the_nilfs *nilfs;
 853         int ret;
 854
 855         nilfs = NILFS_MDT(cpfile)->mi_nilfs;
 856
 857         switch (mode) {
 858         case NILFS_CHECKPOINT:
 859                 /*
 860                  * Check for protecting existing snapshot mounts:
 861                  * bd_mount_sem is used to make this operation atomic and
 862                  * exclusive with a new mount job.  Though it doesn't cover
 863                  * umount, it's enough for the purpose.
 864                  */
 865                 down(&nilfs->ns_bdev->bd_mount_sem);
 866                 if (nilfs_checkpoint_is_mounted(nilfs, cno, 1)) {
 867                         /* Current implementation does not have to protect
 868                            plain read-only mounts since they are exclusive
 869                            with a read/write mount and are protected from the
 870                            cleaner. */
 871                         ret = -EBUSY;
 872                 } else
 873                         ret = nilfs_cpfile_clear_snapshot(cpfile, cno);
 874                 up(&nilfs->ns_bdev->bd_mount_sem);
 875                 return ret;
 876         case NILFS_SNAPSHOT:
 877                 return nilfs_cpfile_set_snapshot(cpfile, cno);
 878         default:
 879                 return -EINVAL;
 880         }
 881 }
 882
 883 /**
 884  * nilfs_cpfile_get_stat - get checkpoint statistics
 885  * @cpfile: inode of checkpoint file
 886  * @stat: pointer to a structure of checkpoint statistics
 887  *
 888  * Description: nilfs_cpfile_get_stat() returns information about checkpoints.
 889  *
 890  * Return Value: On success, 0 is returned, and checkpoints information is
 891  * stored in the place pointed by @stat. On error, one of the following
 892  * negative error codes is returned.
 893  *
 894  * %-EIO - I/O error.
 895  *
 896  * %-ENOMEM - Insufficient amount of memory available.
 897  */
 898 int nilfs_cpfile_get_stat(struct inode *cpfile, struct nilfs_cpstat *cpstat)
 899 {
 900         struct buffer_head *bh;
 901         struct nilfs_cpfile_header *header;
 902         void *kaddr;
 903         int ret;
 904
 905         down_read(&NILFS_MDT(cpfile)->mi_sem);
 906
 907         ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 908         if (ret < 0)
 909                 goto out_sem;
 910         kaddr = kmap_atomic(bh->b_page, KM_USER0);
 911         header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 912         cpstat->cs_cno = nilfs_mdt_cno(cpfile);
 913         cpstat->cs_ncps = le64_to_cpu(header->ch_ncheckpoints);
 914         cpstat->cs_nsss = le64_to_cpu(header->ch_nsnapshots);
 915         kunmap_atomic(kaddr, KM_USER0);
 916         brelse(bh);
 917
 918  out_sem:
 919         up_read(&NILFS_MDT(cpfile)->mi_sem);
 920         return ret;
 921 }