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         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
 305         for (cno = start; cno < end; cno += ncps) {
 306                 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, end);
 307                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 308                 if (ret < 0) {
 309                         if (ret != -ENOENT)
 310                                 goto out_header;
 311                         /* skip hole */
 312                         ret = 0;
 313                         continue;
 314                 }
 315
 316                 kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 317                 cp = nilfs_cpfile_block_get_checkpoint(
 318                         cpfile, cno, cp_bh, kaddr);
 319                 nicps = 0;
 320                 for (i = 0; i < ncps; i++, cp = (void *)cp + cpsz) {
 321                         WARN_ON(nilfs_checkpoint_snapshot(cp));
 322                         if (!nilfs_checkpoint_invalid(cp)) {
 323                                 nilfs_checkpoint_set_invalid(cp);
 324                                 nicps++;
 325                         }
 326                 }
 327                 if (nicps > 0) {
 328                         tnicps += nicps;
 329                         nilfs_mdt_mark_buffer_dirty(cp_bh);
 330                         nilfs_mdt_mark_dirty(cpfile);
 331                         if (!nilfs_cpfile_is_in_first(cpfile, cno) &&
 332                             (count = nilfs_cpfile_block_sub_valid_checkpoints(
 333                                     cpfile, cp_bh, kaddr, nicps)) == 0) {
 334                                 /* make hole */
 335                                 kunmap_atomic(kaddr, KM_USER0);
 336                                 brelse(cp_bh);
 337                                 ret = nilfs_cpfile_delete_checkpoint_block(
 338                                         cpfile, cno);
 339                                 if (ret == 0)
 340                                         continue;
 341                                 printk(KERN_ERR "%s: cannot delete block\n",
 342                                        __func__);
 343                                 goto out_header;
 344                         }
 345                 }
 346
 347                 kunmap_atomic(kaddr, KM_USER0);
 348                 brelse(cp_bh);
 349         }
 350
 351         if (tnicps > 0) {
 352                 kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 353                 header = nilfs_cpfile_block_get_header(cpfile, header_bh,
 354                                                        kaddr);
 355                 le64_add_cpu(&header->ch_ncheckpoints, -(u64)tnicps);
 356                 nilfs_mdt_mark_buffer_dirty(header_bh);
 357                 nilfs_mdt_mark_dirty(cpfile);
 358                 kunmap_atomic(kaddr, KM_USER0);
 359         }
 360
 361  out_header:
 362         brelse(header_bh);
 363
 364  out_sem:
 365         up_write(&NILFS_MDT(cpfile)->mi_sem);
 366         return ret;
 367 }
 368
 369 static void nilfs_cpfile_checkpoint_to_cpinfo(struct inode *cpfile,
 370                                               struct nilfs_checkpoint *cp,
 371                                               struct nilfs_cpinfo *ci)
 372 {
 373         ci->ci_flags = le32_to_cpu(cp->cp_flags);
 374         ci->ci_cno = le64_to_cpu(cp->cp_cno);
 375         ci->ci_create = le64_to_cpu(cp->cp_create);
 376         ci->ci_nblk_inc = le64_to_cpu(cp->cp_nblk_inc);
 377         ci->ci_inodes_count = le64_to_cpu(cp->cp_inodes_count);
 378         ci->ci_blocks_count = le64_to_cpu(cp->cp_blocks_count);
 379         ci->ci_next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
 380 }
 381
 382 static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
 383                                           void *buf, unsigned cisz, size_t nci)
 384 {
 385         struct nilfs_checkpoint *cp;
 386         struct nilfs_cpinfo *ci = buf;
 387         struct buffer_head *bh;
 388         size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 389         __u64 cur_cno = nilfs_mdt_cno(cpfile), cno = *cnop;
 390         void *kaddr;
 391         int n, ret;
 392         int ncps, i;
 393
 394         if (cno == 0)
 395                 return -ENOENT; /* checkpoint number 0 is invalid */
 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(cpfile, cp,
 412                                                                   ci);
 413                                 ci = (void *)ci + cisz;
 414                                 n++;
 415                         }
 416                 }
 417                 kunmap_atomic(kaddr, KM_USER0);
 418                 brelse(bh);
 419         }
 420
 421         ret = n;
 422         if (n > 0) {
 423                 ci = (void *)ci - cisz;
 424                 *cnop = ci->ci_cno + 1;
 425         }
 426
 427  out:
 428         up_read(&NILFS_MDT(cpfile)->mi_sem);
 429         return ret;
 430 }
 431
 432 static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
 433                                           void *buf, unsigned cisz, size_t nci)
 434 {
 435         struct buffer_head *bh;
 436         struct nilfs_cpfile_header *header;
 437         struct nilfs_checkpoint *cp;
 438         struct nilfs_cpinfo *ci = buf;
 439         __u64 curr = *cnop, next;
 440         unsigned long curr_blkoff, next_blkoff;
 441         void *kaddr;
 442         int n = 0, ret;
 443
 444         down_read(&NILFS_MDT(cpfile)->mi_sem);
 445
 446         if (curr == 0) {
 447                 ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 448                 if (ret < 0)
 449                         goto out;
 450                 kaddr = kmap_atomic(bh->b_page, KM_USER0);
 451                 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 452                 curr = le64_to_cpu(header->ch_snapshot_list.ssl_next);
 453                 kunmap_atomic(kaddr, KM_USER0);
 454                 brelse(bh);
 455                 if (curr == 0) {
 456                         ret = 0;
 457                         goto out;
 458                 }
 459         } else if (unlikely(curr == ~(__u64)0)) {
 460                 ret = 0;
 461                 goto out;
 462         }
 463
 464         curr_blkoff = nilfs_cpfile_get_blkoff(cpfile, curr);
 465         ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr, 0, &bh);
 466         if (unlikely(ret < 0)) {
 467                 if (ret == -ENOENT)
 468                         ret = 0; /* No snapshots (started from a hole block) */
 469                 goto out;
 470         }
 471         kaddr = kmap_atomic(bh->b_page, KM_USER0);
 472         while (n < nci) {
 473                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, curr, bh, kaddr);
 474                 curr = ~(__u64)0; /* Terminator */
 475                 if (unlikely(nilfs_checkpoint_invalid(cp) ||
 476                              !nilfs_checkpoint_snapshot(cp)))
 477                         break;
 478                 nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp, ci);
 479                 ci = (void *)ci + cisz;
 480                 n++;
 481                 next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
 482                 if (next == 0)
 483                         break; /* reach end of the snapshot list */
 484
 485                 next_blkoff = nilfs_cpfile_get_blkoff(cpfile, next);
 486                 if (curr_blkoff != next_blkoff) {
 487                         kunmap_atomic(kaddr, KM_USER0);
 488                         brelse(bh);
 489                         ret = nilfs_cpfile_get_checkpoint_block(cpfile, next,
 490                                                                 0, &bh);
 491                         if (unlikely(ret < 0)) {
 492                                 WARN_ON(ret == -ENOENT);
 493                                 goto out;
 494                         }
 495                         kaddr = kmap_atomic(bh->b_page, KM_USER0);
 496                 }
 497                 curr = next;
 498                 curr_blkoff = next_blkoff;
 499         }
 500         kunmap_atomic(kaddr, KM_USER0);
 501         brelse(bh);
 502         *cnop = curr;
 503         ret = n;
 504
 505  out:
 506         up_read(&NILFS_MDT(cpfile)->mi_sem);
 507         return ret;
 508 }
 509
 510 /**
 511  * nilfs_cpfile_get_cpinfo -
 512  * @cpfile:
 513  * @cno:
 514  * @ci:
 515  * @nci:
 516  */
 517
 518 ssize_t nilfs_cpfile_get_cpinfo(struct inode *cpfile, __u64 *cnop, int mode,
 519                                 void *buf, unsigned cisz, size_t nci)
 520 {
 521         switch (mode) {
 522         case NILFS_CHECKPOINT:
 523                 return nilfs_cpfile_do_get_cpinfo(cpfile, cnop, buf, cisz, nci);
 524         case NILFS_SNAPSHOT:
 525                 return nilfs_cpfile_do_get_ssinfo(cpfile, cnop, buf, cisz, nci);
 526         default:
 527                 return -EINVAL;
 528         }
 529 }
 530
 531 /**
 532  * nilfs_cpfile_delete_checkpoint -
 533  * @cpfile:
 534  * @cno:
 535  */
 536 int nilfs_cpfile_delete_checkpoint(struct inode *cpfile, __u64 cno)
 537 {
 538         struct nilfs_cpinfo ci;
 539         __u64 tcno = cno;
 540         ssize_t nci;
 541
 542         nci = nilfs_cpfile_do_get_cpinfo(cpfile, &tcno, &ci, sizeof(ci), 1);
 543         if (nci < 0)
 544                 return nci;
 545         else if (nci == 0 || ci.ci_cno != cno)
 546                 return -ENOENT;
 547         else if (nilfs_cpinfo_snapshot(&ci))
 548                 return -EBUSY;
 549
 550         return nilfs_cpfile_delete_checkpoints(cpfile, cno, cno + 1);
 551 }
 552
 553 static struct nilfs_snapshot_list *
 554 nilfs_cpfile_block_get_snapshot_list(const struct inode *cpfile,
 555                                      __u64 cno,
 556                                      struct buffer_head *bh,
 557                                      void *kaddr)
 558 {
 559         struct nilfs_cpfile_header *header;
 560         struct nilfs_checkpoint *cp;
 561         struct nilfs_snapshot_list *list;
 562
 563         if (cno != 0) {
 564                 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 565                 list = &cp->cp_snapshot_list;
 566         } else {
 567                 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 568                 list = &header->ch_snapshot_list;
 569         }
 570         return list;
 571 }
 572
 573 static int nilfs_cpfile_set_snapshot(struct inode *cpfile, __u64 cno)
 574 {
 575         struct buffer_head *header_bh, *curr_bh, *prev_bh, *cp_bh;
 576         struct nilfs_cpfile_header *header;
 577         struct nilfs_checkpoint *cp;
 578         struct nilfs_snapshot_list *list;
 579         __u64 curr, prev;
 580         unsigned long curr_blkoff, prev_blkoff;
 581         void *kaddr;
 582         int ret;
 583
 584         if (cno == 0)
 585                 return -ENOENT; /* checkpoint number 0 is invalid */
 586         down_write(&NILFS_MDT(cpfile)->mi_sem);
 587
 588         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 589         if (ret < 0)
 590                 goto out_sem;
 591         kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 592         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 593         if (nilfs_checkpoint_invalid(cp)) {
 594                 ret = -ENOENT;
 595                 kunmap_atomic(kaddr, KM_USER0);
 596                 goto out_cp;
 597         }
 598         if (nilfs_checkpoint_snapshot(cp)) {
 599                 ret = 0;
 600                 kunmap_atomic(kaddr, KM_USER0);
 601                 goto out_cp;
 602         }
 603         kunmap_atomic(kaddr, KM_USER0);
 604
 605         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 606         if (ret < 0)
 607                 goto out_cp;
 608         kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 609         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 610         list = &header->ch_snapshot_list;
 611         curr_bh = header_bh;
 612         get_bh(curr_bh);
 613         curr = 0;
 614         curr_blkoff = 0;
 615         prev = le64_to_cpu(list->ssl_prev);
 616         while (prev > cno) {
 617                 prev_blkoff = nilfs_cpfile_get_blkoff(cpfile, prev);
 618                 curr = prev;
 619                 if (curr_blkoff != prev_blkoff) {
 620                         kunmap_atomic(kaddr, KM_USER0);
 621                         brelse(curr_bh);
 622                         ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr,
 623                                                                 0, &curr_bh);
 624                         if (ret < 0)
 625                                 goto out_header;
 626                         kaddr = kmap_atomic(curr_bh->b_page, KM_USER0);
 627                 }
 628                 curr_blkoff = prev_blkoff;
 629                 cp = nilfs_cpfile_block_get_checkpoint(
 630                         cpfile, curr, curr_bh, kaddr);
 631                 list = &cp->cp_snapshot_list;
 632                 prev = le64_to_cpu(list->ssl_prev);
 633         }
 634         kunmap_atomic(kaddr, KM_USER0);
 635
 636         if (prev != 0) {
 637                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 638                                                         &prev_bh);
 639                 if (ret < 0)
 640                         goto out_curr;
 641         } else {
 642                 prev_bh = header_bh;
 643                 get_bh(prev_bh);
 644         }
 645
 646         kaddr = kmap_atomic(curr_bh->b_page, KM_USER0);
 647         list = nilfs_cpfile_block_get_snapshot_list(
 648                 cpfile, curr, curr_bh, kaddr);
 649         list->ssl_prev = cpu_to_le64(cno);
 650         kunmap_atomic(kaddr, KM_USER0);
 651
 652         kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 653         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 654         cp->cp_snapshot_list.ssl_next = cpu_to_le64(curr);
 655         cp->cp_snapshot_list.ssl_prev = cpu_to_le64(prev);
 656         nilfs_checkpoint_set_snapshot(cp);
 657         kunmap_atomic(kaddr, KM_USER0);
 658
 659         kaddr = kmap_atomic(prev_bh->b_page, KM_USER0);
 660         list = nilfs_cpfile_block_get_snapshot_list(
 661                 cpfile, prev, prev_bh, kaddr);
 662         list->ssl_next = cpu_to_le64(cno);
 663         kunmap_atomic(kaddr, KM_USER0);
 664
 665         kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 666         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 667         le64_add_cpu(&header->ch_nsnapshots, 1);
 668         kunmap_atomic(kaddr, KM_USER0);
 669
 670         nilfs_mdt_mark_buffer_dirty(prev_bh);
 671         nilfs_mdt_mark_buffer_dirty(curr_bh);
 672         nilfs_mdt_mark_buffer_dirty(cp_bh);
 673         nilfs_mdt_mark_buffer_dirty(header_bh);
 674         nilfs_mdt_mark_dirty(cpfile);
 675
 676         brelse(prev_bh);
 677
 678  out_curr:
 679         brelse(curr_bh);
 680
 681  out_header:
 682         brelse(header_bh);
 683
 684  out_cp:
 685         brelse(cp_bh);
 686
 687  out_sem:
 688         up_write(&NILFS_MDT(cpfile)->mi_sem);
 689         return ret;
 690 }
 691
 692 static int nilfs_cpfile_clear_snapshot(struct inode *cpfile, __u64 cno)
 693 {
 694         struct buffer_head *header_bh, *next_bh, *prev_bh, *cp_bh;
 695         struct nilfs_cpfile_header *header;
 696         struct nilfs_checkpoint *cp;
 697         struct nilfs_snapshot_list *list;
 698         __u64 next, prev;
 699         void *kaddr;
 700         int ret;
 701
 702         if (cno == 0)
 703                 return -ENOENT; /* checkpoint number 0 is invalid */
 704         down_write(&NILFS_MDT(cpfile)->mi_sem);
 705
 706         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
 707         if (ret < 0)
 708                 goto out_sem;
 709         kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 710         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 711         if (nilfs_checkpoint_invalid(cp)) {
 712                 ret = -ENOENT;
 713                 kunmap_atomic(kaddr, KM_USER0);
 714                 goto out_cp;
 715         }
 716         if (!nilfs_checkpoint_snapshot(cp)) {
 717                 ret = 0;
 718                 kunmap_atomic(kaddr, KM_USER0);
 719                 goto out_cp;
 720         }
 721
 722         list = &cp->cp_snapshot_list;
 723         next = le64_to_cpu(list->ssl_next);
 724         prev = le64_to_cpu(list->ssl_prev);
 725         kunmap_atomic(kaddr, KM_USER0);
 726
 727         ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
 728         if (ret < 0)
 729                 goto out_cp;
 730         if (next != 0) {
 731                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, next, 0,
 732                                                         &next_bh);
 733                 if (ret < 0)
 734                         goto out_header;
 735         } else {
 736                 next_bh = header_bh;
 737                 get_bh(next_bh);
 738         }
 739         if (prev != 0) {
 740                 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
 741                                                         &prev_bh);
 742                 if (ret < 0)
 743                         goto out_next;
 744         } else {
 745                 prev_bh = header_bh;
 746                 get_bh(prev_bh);
 747         }
 748
 749         kaddr = kmap_atomic(next_bh->b_page, KM_USER0);
 750         list = nilfs_cpfile_block_get_snapshot_list(
 751                 cpfile, next, next_bh, kaddr);
 752         list->ssl_prev = cpu_to_le64(prev);
 753         kunmap_atomic(kaddr, KM_USER0);
 754
 755         kaddr = kmap_atomic(prev_bh->b_page, KM_USER0);
 756         list = nilfs_cpfile_block_get_snapshot_list(
 757                 cpfile, prev, prev_bh, kaddr);
 758         list->ssl_next = cpu_to_le64(next);
 759         kunmap_atomic(kaddr, KM_USER0);
 760
 761         kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
 762         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
 763         cp->cp_snapshot_list.ssl_next = cpu_to_le64(0);
 764         cp->cp_snapshot_list.ssl_prev = cpu_to_le64(0);
 765         nilfs_checkpoint_clear_snapshot(cp);
 766         kunmap_atomic(kaddr, KM_USER0);
 767
 768         kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
 769         header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
 770         le64_add_cpu(&header->ch_nsnapshots, -1);
 771         kunmap_atomic(kaddr, KM_USER0);
 772
 773         nilfs_mdt_mark_buffer_dirty(next_bh);
 774         nilfs_mdt_mark_buffer_dirty(prev_bh);
 775         nilfs_mdt_mark_buffer_dirty(cp_bh);
 776         nilfs_mdt_mark_buffer_dirty(header_bh);
 777         nilfs_mdt_mark_dirty(cpfile);
 778
 779         brelse(prev_bh);
 780
 781  out_next:
 782         brelse(next_bh);
 783
 784  out_header:
 785         brelse(header_bh);
 786
 787  out_cp:
 788         brelse(cp_bh);
 789
 790  out_sem:
 791         up_write(&NILFS_MDT(cpfile)->mi_sem);
 792         return ret;
 793 }
 794
 795 /**
 796  * nilfs_cpfile_is_snapshot -
 797  * @cpfile: inode of checkpoint file
 798  * @cno: checkpoint number
 799  *
 800  * Description:
 801  *
 802  * Return Value: On success, 1 is returned if the checkpoint specified by
 803  * @cno is a snapshot, or 0 if not. On error, one of the following negative
 804  * error codes is returned.
 805  *
 806  * %-EIO - I/O error.
 807  *
 808  * %-ENOMEM - Insufficient amount of memory available.
 809  *
 810  * %-ENOENT - No such checkpoint.
 811  */
 812 int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
 813 {
 814         struct buffer_head *bh;
 815         struct nilfs_checkpoint *cp;
 816         void *kaddr;
 817         int ret;
 818
 819         if (cno == 0)
 820                 return -ENOENT; /* checkpoint number 0 is invalid */
 821         down_read(&NILFS_MDT(cpfile)->mi_sem);
 822
 823         ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
 824         if (ret < 0)
 825                 goto out;
 826         kaddr = kmap_atomic(bh->b_page, KM_USER0);
 827         cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
 828         ret = nilfs_checkpoint_snapshot(cp);
 829         kunmap_atomic(kaddr, KM_USER0);
 830         brelse(bh);
 831
 832  out:
 833         up_read(&NILFS_MDT(cpfile)->mi_sem);
 834         return ret;
 835 }
 836
 837 /**
 838  * nilfs_cpfile_change_cpmode - change checkpoint mode
 839  * @cpfile: inode of checkpoint file
 840  * @cno: checkpoint number
 841  * @status: mode of checkpoint
 842  *
 843  * Description: nilfs_change_cpmode() changes the mode of the checkpoint
 844  * specified by @cno. The mode @mode is NILFS_CHECKPOINT or NILFS_SNAPSHOT.
 845  *
 846  * Return Value: On success, 0 is returned. On error, one of the following
 847  * negative error codes is returned.
 848  *
 849  * %-EIO - I/O error.
 850  *
 851  * %-ENOMEM - Insufficient amount of memory available.
 852  *
 853  * %-ENOENT - No such checkpoint.
 854  */
 855 int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
 856 {
 857         struct the_nilfs *nilfs;
 858         int ret;
 859
 860         nilfs = NILFS_MDT(cpfile)->mi_nilfs;
 861
 862         switch (mode) {
 863         case NILFS_CHECKPOINT:
 864                 /*
 865                  * Check for protecting existing snapshot mounts:
 866                  * ns_mount_mutex is used to make this operation atomic and
 867                  * exclusive with a new mount job.  Though it doesn't cover
 868                  * umount, it's enough for the purpose.
 869                  */
 870                 mutex_lock(&nilfs->ns_mount_mutex);
 871                 if (nilfs_checkpoint_is_mounted(nilfs, cno, 1)) {
 872                         /* Current implementation does not have to protect
 873                            plain read-only mounts since they are exclusive
 874                            with a read/write mount and are protected from the
 875                            cleaner. */
 876                         ret = -EBUSY;
 877                 } else
 878                         ret = nilfs_cpfile_clear_snapshot(cpfile, cno);
 879                 mutex_unlock(&nilfs->ns_mount_mutex);
 880                 return ret;
 881         case NILFS_SNAPSHOT:
 882                 return nilfs_cpfile_set_snapshot(cpfile, cno);
 883         default:
 884                 return -EINVAL;
 885         }
 886 }
 887
 888 /**
 889  * nilfs_cpfile_get_stat - get checkpoint statistics
 890  * @cpfile: inode of checkpoint file
 891  * @stat: pointer to a structure of checkpoint statistics
 892  *
 893  * Description: nilfs_cpfile_get_stat() returns information about checkpoints.
 894  *
 895  * Return Value: On success, 0 is returned, and checkpoints information is
 896  * stored in the place pointed by @stat. On error, one of the following
 897  * negative error codes is returned.
 898  *
 899  * %-EIO - I/O error.
 900  *
 901  * %-ENOMEM - Insufficient amount of memory available.
 902  */
 903 int nilfs_cpfile_get_stat(struct inode *cpfile, struct nilfs_cpstat *cpstat)
 904 {
 905         struct buffer_head *bh;
 906         struct nilfs_cpfile_header *header;
 907         void *kaddr;
 908         int ret;
 909
 910         down_read(&NILFS_MDT(cpfile)->mi_sem);
 911
 912         ret = nilfs_cpfile_get_header_block(cpfile, &bh);
 913         if (ret < 0)
 914                 goto out_sem;
 915         kaddr = kmap_atomic(bh->b_page, KM_USER0);
 916         header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
 917         cpstat->cs_cno = nilfs_mdt_cno(cpfile);
 918         cpstat->cs_ncps = le64_to_cpu(header->ch_ncheckpoints);
 919         cpstat->cs_nsss = le64_to_cpu(header->ch_nsnapshots);
 920         kunmap_atomic(kaddr, KM_USER0);
 921         brelse(bh);
 922
 923  out_sem:
 924         up_read(&NILFS_MDT(cpfile)->mi_sem);
 925         return ret;
 926 }