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 = 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                 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 (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         /* cannot delete the latest checkpoint */
 299         if (start == nilfs_mdt_cno(cpfile) - 1)
 300                 return -EPERM;
 301
 302         down_write(&NILFS_MDT(cpfile)->mi_sem);
 303
 304         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 305         if (ret < 0)
 306                 goto out_sem;
 307         tnicps = 0;
 308
 309         for (cno = start; cno < end; cno += ncps) {
 310                 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, end);
 311                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 312                 if (ret < 0) {
 313                         if (ret != -ENOENT)
 314                                 goto out_header;
 315                         /* skip hole */
 316                         ret = 0;
 317                         continue;
 318                 }
 319
 320                 kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 321                 cp = nilfs_cpfile_block_get_checkpoint(
 322                         cpfile, cno, cp_bh, kaddr);
 323                 nicps = 0;
 324                 for (i = 0; i < ncps; i++, cp = (void *)cp + cpsz) {
 325                         WARN_ON(nilfs_checkpoint_snapshot(cp));
 326                         if (!nilfs_checkpoint_invalid(cp)) {
 327                                 nilfs_checkpoint_set_invalid(cp);
 328                                 nicps++;
 329                         }
 330                 }
 331                 if (nicps > 0) {
 332                         tnicps += nicps;
 333                         nilfs_mdt_mark_buffer_dirty(cp_bh);
 334                         nilfs_mdt_mark_dirty(cpfile);
 335                         if (!nilfs_cpfile_is_in_first(cpfile, cno) &&
 336                             (count = nilfs_cpfile_block_sub_valid_checkpoints(
 337                                     cpfile, cp_bh, kaddr, nicps)) == 0) {
 338                                 /* make hole */
 339                                 kunmap_atomic(kaddr, KM_USER0);
 340                                 brelse(cp_bh);
 341                                 ret = nilfs_cpfile_delete_checkpoint_block(
 342                                         cpfile, cno);
 343                                 if (ret == 0)
 344                                         continue;
 345                                 printk(KERN_ERR "%s: cannot delete block\n",
 346                                        __func__);
 347                                 goto out_header;
 348                         }
 349                 }
 350
 351                 kunmap_atomic(kaddr, KM_USER0);
 352                 brelse(cp_bh);
 353         }
 354
 355         if (tnicps > 0) {
 356                 kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 357                 header = nilfs_cpfile_block_get_header(cpfile, header_bh,
 358                                                        kaddr);
 359                 le64_add_cpu(&header->ch_ncheckpoints, -(u64)tnicps);
 360                 nilfs_mdt_mark_buffer_dirty(header_bh);
 361                 nilfs_mdt_mark_dirty(cpfile);
 362                 kunmap_atomic(kaddr, KM_USER0);
 363         }
 364
 365  out_header:
 366         brelse(header_bh);
 367
 368  out_sem:
 369         up_write(&NILFS_MDT(cpfile)->mi_sem);
 370         return ret;
 371 }
 372
 373 static void nilfs_cpfile_checkpoint_to_cpinfo(struct inode *cpfile,
 374                                               struct nilfs_checkpoint *cp,
 375                                               struct nilfs_cpinfo *ci)
 376 {
 377         ci->ci_flags = le32_to_cpu(cp->cp_flags);
 378         ci->ci_cno = le64_to_cpu(cp->cp_cno);
 379         ci->ci_create = le64_to_cpu(cp->cp_create);
 380         ci->ci_nblk_inc = le64_to_cpu(cp->cp_nblk_inc);
 381         ci->ci_inodes_count = le64_to_cpu(cp->cp_inodes_count);
 382         ci->ci_blocks_count = le64_to_cpu(cp->cp_blocks_count);
 383         ci->ci_next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
 384 }
 385
 386 static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
 387                                           void *buf, unsigned cisz, size_t nci)
 388 {
 389         struct nilfs_checkpoint *cp;
 390         struct nilfs_cpinfo *ci = buf;
 391         struct buffer_head *bh;
 392         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 393         __u64 cur_cno = nilfs_mdt_cno(cpfile), cno = *cnop;
 394         void *kaddr;
 395         int n, ret;
 396         int ncps, i;
 397
 398         if (cno == 0)
 399                 return -ENOENT; /* checkpoint number 0 is invalid */
 400         down_read(&NILFS_MDT(cpfile)->mi_sem);
 401
 402         for (n = 0; cno < cur_cno && n < nci; cno += ncps) {
 403                 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
 404                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
 405                 if (ret < 0) {
 406                         if (ret != -ENOENT)
 407                                 goto out;
 408                         continue; /* skip hole */
 409                 }
 410
 411                 kaddr = kmap_atomic(bh->b_page, KM_USER0);
 412                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 413                 for (i = 0; i < ncps && n < nci; i++, cp = (void *)cp + cpsz) {
 414                         if (!nilfs_checkpoint_invalid(cp)) {
 415                                 nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp,
 416                                                                   ci);
 417                                 ci = (void *)ci + cisz;
 418                                 n++;
 419                         }
 420                 }
 421                 kunmap_atomic(kaddr, KM_USER0);
 422                 brelse(bh);
 423         }
 424
 425         ret = n;
 426         if (n > 0) {
 427                 ci = (void *)ci - cisz;
 428                 *cnop = ci->ci_cno + 1;
 429         }
 430
 431  out:
 432         up_read(&NILFS_MDT(cpfile)->mi_sem);
 433         return ret;
 434 }
 435
 436 static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
 437                                           void *buf, unsigned cisz, size_t nci)
 438 {
 439         struct buffer_head *bh;
 440         struct nilfs_cpfile_header *header;
 441         struct nilfs_checkpoint *cp;
 442         struct nilfs_cpinfo *ci = buf;
 443         __u64 curr = *cnop, next;
 444         unsigned long curr_blkoff, next_blkoff;
 445         void *kaddr;
 446         int n = 0, ret;
 447
 448         down_read(&NILFS_MDT(cpfile)->mi_sem);
 449
 450         if (curr == 0) {
 451                 ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 452                 if (ret < 0)
 453                         goto out;
 454                 kaddr = kmap_atomic(bh->b_page, KM_USER0);
 455                 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 456                 curr = le64_to_cpu(header->ch_snapshot_list.ssl_next);
 457                 kunmap_atomic(kaddr, KM_USER0);
 458                 brelse(bh);
 459                 if (curr == 0) {
 460                         ret = 0;
 461                         goto out;
 462                 }
 463         } else if (unlikely(curr == ~(__u64)0)) {
 464                 ret = 0;
 465                 goto out;
 466         }
 467
 468         curr_blkoff = nilfs_cpfile_get_blkoff(cpfile, curr);
 469         ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr, 0, &bh);
 470         if (unlikely(ret < 0)) {
 471                 if (ret == -ENOENT)
 472                         ret = 0; /* No snapshots (started from a hole block) */
 473                 goto out;
 474         }
 475         kaddr = kmap_atomic(bh->b_page, KM_USER0);
 476         while (n < nci) {
 477                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, curr, bh, kaddr);
 478                 curr = ~(__u64)0; /* Terminator */
 479                 if (unlikely(nilfs_checkpoint_invalid(cp) ||
 480                              !nilfs_checkpoint_snapshot(cp)))
 481                         break;
 482                 nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp, ci);
 483                 ci = (void *)ci + cisz;
 484                 n++;
 485                 next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
 486                 if (next == 0)
 487                         break; /* reach end of the snapshot list */
 488
 489                 next_blkoff = nilfs_cpfile_get_blkoff(cpfile, next);
 490                 if (curr_blkoff != next_blkoff) {
 491                         kunmap_atomic(kaddr, KM_USER0);
 492                         brelse(bh);
 493                         ret = nilfs_cpfile_get_checkpoint_block(cpfile, next,
 494                                                                 0, &bh);
 495                         if (unlikely(ret < 0)) {
 496                                 WARN_ON(ret == -ENOENT);
 497                                 goto out;
 498                         }
 499                         kaddr = kmap_atomic(bh->b_page, KM_USER0);
 500                 }
 501                 curr = next;
 502                 curr_blkoff = next_blkoff;
 503         }
 504         kunmap_atomic(kaddr, KM_USER0);
 505         brelse(bh);
 506         *cnop = curr;
 507         ret = n;
 508
 509  out:
 510         up_read(&NILFS_MDT(cpfile)->mi_sem);
 511         return ret;
 512 }
 513
 514 /**
 515  * nilfs_cpfile_get_cpinfo -
 516  * @cpfile:
 517  * @cno:
 518  * @ci:
 519  * @nci:
 520  */
 521
 522 ssize_t nilfs_cpfile_get_cpinfo(struct inode *cpfile, __u64 *cnop, int mode,
 523                                 void *buf, unsigned cisz, size_t nci)
 524 {
 525         switch (mode) {
 526         case NILFS_CHECKPOINT:
 527                 return nilfs_cpfile_do_get_cpinfo(cpfile, cnop, buf, cisz, nci);
 528         case NILFS_SNAPSHOT:
 529                 return nilfs_cpfile_do_get_ssinfo(cpfile, cnop, buf, cisz, nci);
 530         default:
 531                 return -EINVAL;
 532         }
 533 }
 534
 535 /**
 536  * nilfs_cpfile_delete_checkpoint -
 537  * @cpfile:
 538  * @cno:
 539  */
 540 int nilfs_cpfile_delete_checkpoint(struct inode *cpfile, __u64 cno)
 541 {
 542         struct nilfs_cpinfo ci;
 543         __u64 tcno = cno;
 544         ssize_t nci;
 545         int ret;
 546
 547         nci = nilfs_cpfile_do_get_cpinfo(cpfile, &tcno, &ci, sizeof(ci), 1);
 548         if (nci < 0)
 549                 return nci;
 550         else if (nci == 0 || ci.ci_cno != cno)
 551                 return -ENOENT;
 552
 553         /* cannot delete the latest checkpoint nor snapshots */
 554         ret = nilfs_cpinfo_snapshot(&ci);
 555         if (ret < 0)
 556                 return ret;
 557         else if (ret > 0 || cno == nilfs_mdt_cno(cpfile) - 1)
 558                 return -EPERM;
 559
 560         return nilfs_cpfile_delete_checkpoints(cpfile, cno, cno + 1);
 561 }
 562
 563 static struct nilfs_snapshot_list *
 564 nilfs_cpfile_block_get_snapshot_list(const struct inode *cpfile,
 565                                      __u64 cno,
 566                                      struct buffer_head *bh,
 567                                      void *kaddr)
 568 {
 569         struct nilfs_cpfile_header *header;
 570         struct nilfs_checkpoint *cp;
 571         struct nilfs_snapshot_list *list;
 572
 573         if (cno != 0) {
 574                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 575                 list = &cp->cp_snapshot_list;
 576         } else {
 577                 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 578                 list = &header->ch_snapshot_list;
 579         }
 580         return list;
 581 }
 582
 583 static int nilfs_cpfile_set_snapshot(struct inode *cpfile, __u64 cno)
 584 {
 585         struct buffer_head *header_bh, *curr_bh, *prev_bh, *cp_bh;
 586         struct nilfs_cpfile_header *header;
 587         struct nilfs_checkpoint *cp;
 588         struct nilfs_snapshot_list *list;
 589         __u64 curr, prev;
 590         unsigned long curr_blkoff, prev_blkoff;
 591         void *kaddr;
 592         int ret;
 593
 594         if (cno == 0)
 595                 return -ENOENT; /* checkpoint number 0 is invalid */
 596         down_write(&NILFS_MDT(cpfile)->mi_sem);
 597
 598         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 599         if (ret < 0)
 600                 goto out_sem;
 601         kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 602         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 603         if (nilfs_checkpoint_invalid(cp)) {
 604                 ret = -ENOENT;
 605                 kunmap_atomic(kaddr, KM_USER0);
 606                 goto out_cp;
 607         }
 608         if (nilfs_checkpoint_snapshot(cp)) {
 609                 ret = 0;
 610                 kunmap_atomic(kaddr, KM_USER0);
 611                 goto out_cp;
 612         }
 613         kunmap_atomic(kaddr, KM_USER0);
 614
 615         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 616         if (ret < 0)
 617                 goto out_cp;
 618         kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 619         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 620         list = &header->ch_snapshot_list;
 621         curr_bh = header_bh;
 622         get_bh(curr_bh);
 623         curr = 0;
 624         curr_blkoff = 0;
 625         prev = le64_to_cpu(list->ssl_prev);
 626         while (prev > cno) {
 627                 prev_blkoff = nilfs_cpfile_get_blkoff(cpfile, prev);
 628                 curr = prev;
 629                 if (curr_blkoff != prev_blkoff) {
 630                         kunmap_atomic(kaddr, KM_USER0);
 631                         brelse(curr_bh);
 632                         ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr,
 633                                                                 0, &curr_bh);
 634                         if (ret < 0)
 635                                 goto out_header;
 636                         kaddr = kmap_atomic(curr_bh->b_page, KM_USER0);
 637                 }
 638                 curr_blkoff = prev_blkoff;
 639                 cp = nilfs_cpfile_block_get_checkpoint(
 640                         cpfile, curr, curr_bh, kaddr);
 641                 list = &cp->cp_snapshot_list;
 642                 prev = le64_to_cpu(list->ssl_prev);
 643         }
 644         kunmap_atomic(kaddr, KM_USER0);
 645
 646         if (prev != 0) {
 647                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 648                                                         &prev_bh);
 649                 if (ret < 0)
 650                         goto out_curr;
 651         } else {
 652                 prev_bh = header_bh;
 653                 get_bh(prev_bh);
 654         }
 655
 656         kaddr = kmap_atomic(curr_bh->b_page, KM_USER0);
 657         list = nilfs_cpfile_block_get_snapshot_list(
 658                 cpfile, curr, curr_bh, kaddr);
 659         list->ssl_prev = cpu_to_le64(cno);
 660         kunmap_atomic(kaddr, KM_USER0);
 661
 662         kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 663         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 664         cp->cp_snapshot_list.ssl_next = cpu_to_le64(curr);
 665         cp->cp_snapshot_list.ssl_prev = cpu_to_le64(prev);
 666         nilfs_checkpoint_set_snapshot(cp);
 667         kunmap_atomic(kaddr, KM_USER0);
 668
 669         kaddr = kmap_atomic(prev_bh->b_page, KM_USER0);
 670         list = nilfs_cpfile_block_get_snapshot_list(
 671                 cpfile, prev, prev_bh, kaddr);
 672         list->ssl_next = cpu_to_le64(cno);
 673         kunmap_atomic(kaddr, KM_USER0);
 674
 675         kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 676         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 677         le64_add_cpu(&header->ch_nsnapshots, 1);
 678         kunmap_atomic(kaddr, KM_USER0);
 679
 680         nilfs_mdt_mark_buffer_dirty(prev_bh);
 681         nilfs_mdt_mark_buffer_dirty(curr_bh);
 682         nilfs_mdt_mark_buffer_dirty(cp_bh);
 683         nilfs_mdt_mark_buffer_dirty(header_bh);
 684         nilfs_mdt_mark_dirty(cpfile);
 685
 686         brelse(prev_bh);
 687
 688  out_curr:
 689         brelse(curr_bh);
 690
 691  out_header:
 692         brelse(header_bh);
 693
 694  out_cp:
 695         brelse(cp_bh);
 696
 697  out_sem:
 698         up_write(&NILFS_MDT(cpfile)->mi_sem);
 699         return ret;
 700 }
 701
 702 static int nilfs_cpfile_clear_snapshot(struct inode *cpfile, __u64 cno)
 703 {
 704         struct buffer_head *header_bh, *next_bh, *prev_bh, *cp_bh;
 705         struct nilfs_cpfile_header *header;
 706         struct nilfs_checkpoint *cp;
 707         struct nilfs_snapshot_list *list;
 708         __u64 next, prev;
 709         void *kaddr;
 710         int ret;
 711
 712         if (cno == 0)
 713                 return -ENOENT; /* checkpoint number 0 is invalid */
 714         down_write(&NILFS_MDT(cpfile)->mi_sem);
 715
 716         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 717         if (ret < 0)
 718                 goto out_sem;
 719         kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 720         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 721         if (nilfs_checkpoint_invalid(cp)) {
 722                 ret = -ENOENT;
 723                 kunmap_atomic(kaddr, KM_USER0);
 724                 goto out_cp;
 725         }
 726         if (!nilfs_checkpoint_snapshot(cp)) {
 727                 ret = 0;
 728                 kunmap_atomic(kaddr, KM_USER0);
 729                 goto out_cp;
 730         }
 731
 732         list = &cp->cp_snapshot_list;
 733         next = le64_to_cpu(list->ssl_next);
 734         prev = le64_to_cpu(list->ssl_prev);
 735         kunmap_atomic(kaddr, KM_USER0);
 736
 737         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 738         if (ret < 0)
 739                 goto out_cp;
 740         if (next != 0) {
 741                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, next, 0,
 742                                                         &next_bh);
 743                 if (ret < 0)
 744                         goto out_header;
 745         } else {
 746                 next_bh = header_bh;
 747                 get_bh(next_bh);
 748         }
 749         if (prev != 0) {
 750                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 751                                                         &prev_bh);
 752                 if (ret < 0)
 753                         goto out_next;
 754         } else {
 755                 prev_bh = header_bh;
 756                 get_bh(prev_bh);
 757         }
 758
 759         kaddr = kmap_atomic(next_bh->b_page, KM_USER0);
 760         list = nilfs_cpfile_block_get_snapshot_list(
 761                 cpfile, next, next_bh, kaddr);
 762         list->ssl_prev = cpu_to_le64(prev);
 763         kunmap_atomic(kaddr, KM_USER0);
 764
 765         kaddr = kmap_atomic(prev_bh->b_page, KM_USER0);
 766         list = nilfs_cpfile_block_get_snapshot_list(
 767                 cpfile, prev, prev_bh, kaddr);
 768         list->ssl_next = cpu_to_le64(next);
 769         kunmap_atomic(kaddr, KM_USER0);
 770
 771         kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 772         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 773         cp->cp_snapshot_list.ssl_next = cpu_to_le64(0);
 774         cp->cp_snapshot_list.ssl_prev = cpu_to_le64(0);
 775         nilfs_checkpoint_clear_snapshot(cp);
 776         kunmap_atomic(kaddr, KM_USER0);
 777
 778         kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 779         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 780         le64_add_cpu(&header->ch_nsnapshots, -1);
 781         kunmap_atomic(kaddr, KM_USER0);
 782
 783         nilfs_mdt_mark_buffer_dirty(next_bh);
 784         nilfs_mdt_mark_buffer_dirty(prev_bh);
 785         nilfs_mdt_mark_buffer_dirty(cp_bh);
 786         nilfs_mdt_mark_buffer_dirty(header_bh);
 787         nilfs_mdt_mark_dirty(cpfile);
 788
 789         brelse(prev_bh);
 790
 791  out_next:
 792         brelse(next_bh);
 793
 794  out_header:
 795         brelse(header_bh);
 796
 797  out_cp:
 798         brelse(cp_bh);
 799
 800  out_sem:
 801         up_write(&NILFS_MDT(cpfile)->mi_sem);
 802         return ret;
 803 }
 804
 805 /**
 806  * nilfs_cpfile_is_snapshot -
 807  * @cpfile: inode of checkpoint file
 808  * @cno: checkpoint number
 809  *
 810  * Description:
 811  *
 812  * Return Value: On success, 1 is returned if the checkpoint specified by
 813  * @cno is a snapshot, or 0 if not. On error, one of the following negative
 814  * error codes is returned.
 815  *
 816  * %-EIO - I/O error.
 817  *
 818  * %-ENOMEM - Insufficient amount of memory available.
 819  *
 820  * %-ENOENT - No such checkpoint.
 821  */
 822 int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
 823 {
 824         struct buffer_head *bh;
 825         struct nilfs_checkpoint *cp;
 826         void *kaddr;
 827         int ret;
 828
 829         if (cno == 0)
 830                 return -ENOENT; /* checkpoint number 0 is invalid */
 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, KM_USER0);
 837         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 838         ret = nilfs_checkpoint_snapshot(cp);
 839         kunmap_atomic(kaddr, KM_USER0);
 840         brelse(bh);
 841
 842  out:
 843         up_read(&NILFS_MDT(cpfile)->mi_sem);
 844         return ret;
 845 }
 846
 847 /**
 848  * nilfs_cpfile_change_cpmode - change checkpoint mode
 849  * @cpfile: inode of checkpoint file
 850  * @cno: checkpoint number
 851  * @status: mode of checkpoint
 852  *
 853  * Description: nilfs_change_cpmode() changes the mode of the checkpoint
 854  * specified by @cno. The mode @mode is NILFS_CHECKPOINT or NILFS_SNAPSHOT.
 855  *
 856  * Return Value: On success, 0 is returned. On error, one of the following
 857  * negative error codes is returned.
 858  *
 859  * %-EIO - I/O error.
 860  *
 861  * %-ENOMEM - Insufficient amount of memory available.
 862  *
 863  * %-ENOENT - No such checkpoint.
 864  */
 865 int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
 866 {
 867         struct the_nilfs *nilfs;
 868         int ret;
 869
 870         nilfs = NILFS_MDT(cpfile)->mi_nilfs;
 871
 872         switch (mode) {
 873         case NILFS_CHECKPOINT:
 874                 /*
 875                  * Check for protecting existing snapshot mounts:
 876                  * bd_mount_sem is used to make this operation atomic and
 877                  * exclusive with a new mount job.  Though it doesn't cover
 878                  * umount, it's enough for the purpose.
 879                  */
 880                 down(&nilfs->ns_bdev->bd_mount_sem);
 881                 if (nilfs_checkpoint_is_mounted(nilfs, cno, 1)) {
 882                         /* Current implementation does not have to protect
 883                            plain read-only mounts since they are exclusive
 884                            with a read/write mount and are protected from the
 885                            cleaner. */
 886                         ret = -EBUSY;
 887                 } else
 888                         ret = nilfs_cpfile_clear_snapshot(cpfile, cno);
 889                 up(&nilfs->ns_bdev->bd_mount_sem);
 890                 return ret;
 891         case NILFS_SNAPSHOT:
 892                 return nilfs_cpfile_set_snapshot(cpfile, cno);
 893         default:
 894                 return -EINVAL;
 895         }
 896 }
 897
 898 /**
 899  * nilfs_cpfile_get_stat - get checkpoint statistics
 900  * @cpfile: inode of checkpoint file
 901  * @stat: pointer to a structure of checkpoint statistics
 902  *
 903  * Description: nilfs_cpfile_get_stat() returns information about checkpoints.
 904  *
 905  * Return Value: On success, 0 is returned, and checkpoints information is
 906  * stored in the place pointed by @stat. On error, one of the following
 907  * negative error codes is returned.
 908  *
 909  * %-EIO - I/O error.
 910  *
 911  * %-ENOMEM - Insufficient amount of memory available.
 912  */
 913 int nilfs_cpfile_get_stat(struct inode *cpfile, struct nilfs_cpstat *cpstat)
 914 {
 915         struct buffer_head *bh;
 916         struct nilfs_cpfile_header *header;
 917         void *kaddr;
 918         int ret;
 919
 920         down_read(&NILFS_MDT(cpfile)->mi_sem);
 921
 922         ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 923         if (ret < 0)
 924                 goto out_sem;
 925         kaddr = kmap_atomic(bh->b_page, KM_USER0);
 926         header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 927         cpstat->cs_cno = nilfs_mdt_cno(cpfile);
 928         cpstat->cs_ncps = le64_to_cpu(header->ch_ncheckpoints);
 929         cpstat->cs_nsss = le64_to_cpu(header->ch_nsnapshots);
 930         kunmap_atomic(kaddr, KM_USER0);
 931         brelse(bh);
 932
 933  out_sem:
 934         up_read(&NILFS_MDT(cpfile)->mi_sem);
 935         return ret;
 936 }