fs/ocfs2/buffer_head_io.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * io.c
   5  *
   6  * Buffer cache handling
   7  *
   8  * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public
  12  * License as published by the Free Software Foundation; either
  13  * version 2 of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public
  21  * License along with this program; if not, write to the
  22  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23  * Boston, MA 021110-1307, USA.
  24  */
  25
  26 #include <linux/fs.h>
  27 #include <linux/types.h>
  28 #include <linux/highmem.h>
  29
  30 #include <cluster/masklog.h>
  31
  32 #include "ocfs2.h"
  33
  34 #include "alloc.h"
  35 #include "inode.h"
  36 #include "journal.h"
  37 #include "uptodate.h"
  38
  39 #include "buffer_head_io.h"
  40
  41 /*
  42  * Bits on bh->b_state used by ocfs2.
  43  *
  44  * These MUST be after the JBD2 bits.  Hence, we use BH_JBDPrivateStart.
  45  */
  46 enum ocfs2_state_bits {
  47         BH_NeedsValidate = BH_JBDPrivateStart,
  48 };
  49
  50 /* Expand the magic b_state functions */
  51 BUFFER_FNS(NeedsValidate, needs_validate);
  52
  53 int ocfs2_write_block(struct ocfs2_super *osb, struct buffer_head *bh,
  54                       struct ocfs2_caching_info *ci)
  55 {
  56         int ret = 0;
  57
  58         mlog_entry("(bh->b_blocknr = %llu, ci=%p)\n",
  59                    (unsigned long long)bh->b_blocknr, ci);
  60
  61         BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO);
  62         BUG_ON(buffer_jbd(bh));
  63
  64         /* No need to check for a soft readonly file system here. non
  65          * journalled writes are only ever done on system files which
  66          * can get modified during recovery even if read-only. */
  67         if (ocfs2_is_hard_readonly(osb)) {
  68                 ret = -EROFS;
  69                 goto out;
  70         }
  71
  72         ocfs2_metadata_cache_io_lock(ci);
  73
  74         lock_buffer(bh);
  75         set_buffer_uptodate(bh);
  76
  77         /* remove from dirty list before I/O. */
  78         clear_buffer_dirty(bh);
  79
  80         get_bh(bh); /* for end_buffer_write_sync() */
  81         bh->b_end_io = end_buffer_write_sync;
  82         submit_bh(WRITE, bh);
  83
  84         wait_on_buffer(bh);
  85
  86         if (buffer_uptodate(bh)) {
  87                 ocfs2_set_buffer_uptodate(ci, bh);
  88         } else {
  89                 /* We don't need to remove the clustered uptodate
  90                  * information for this bh as it's not marked locally
  91                  * uptodate. */
  92                 ret = -EIO;
  93                 put_bh(bh);
  94         }
  95
  96         ocfs2_metadata_cache_io_unlock(ci);
  97 out:
  98         mlog_exit(ret);
  99         return ret;
 100 }
 101
 102 int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
 103                            unsigned int nr, struct buffer_head *bhs[])
 104 {
 105         int status = 0;
 106         unsigned int i;
 107         struct buffer_head *bh;
 108
 109         if (!nr) {
 110                 mlog(ML_BH_IO, "No buffers will be read!\n");
 111                 goto bail;
 112         }
 113
 114         for (i = 0 ; i < nr ; i++) {
 115                 if (bhs[i] == NULL) {
 116                         bhs[i] = sb_getblk(osb->sb, block++);
 117                         if (bhs[i] == NULL) {
 118                                 status = -EIO;
 119                                 mlog_errno(status);
 120                                 goto bail;
 121                         }
 122                 }
 123                 bh = bhs[i];
 124
 125                 if (buffer_jbd(bh)) {
 126                         mlog(ML_BH_IO,
 127                              "trying to sync read a jbd "
 128                              "managed bh (blocknr = %llu), skipping\n",
 129                              (unsigned long long)bh->b_blocknr);
 130                         continue;
 131                 }
 132
 133                 if (buffer_dirty(bh)) {
 134                         /* This should probably be a BUG, or
 135                          * at least return an error. */
 136                         mlog(ML_ERROR,
 137                              "trying to sync read a dirty "
 138                              "buffer! (blocknr = %llu), skipping\n",
 139                              (unsigned long long)bh->b_blocknr);
 140                         continue;
 141                 }
 142
 143                 lock_buffer(bh);
 144                 if (buffer_jbd(bh)) {
 145                         mlog(ML_ERROR,
 146                              "block %llu had the JBD bit set "
 147                              "while I was in lock_buffer!",
 148                              (unsigned long long)bh->b_blocknr);
 149                         BUG();
 150                 }
 151
 152                 clear_buffer_uptodate(bh);
 153                 get_bh(bh); /* for end_buffer_read_sync() */
 154                 bh->b_end_io = end_buffer_read_sync;
 155                 submit_bh(READ, bh);
 156         }
 157
 158         for (i = nr; i > 0; i--) {
 159                 bh = bhs[i - 1];
 160
 161                 /* No need to wait on the buffer if it's managed by JBD. */
 162                 if (!buffer_jbd(bh))
 163                         wait_on_buffer(bh);
 164
 165                 if (!buffer_uptodate(bh)) {
 166                         /* Status won't be cleared from here on out,
 167                          * so we can safely record this and loop back
 168                          * to cleanup the other buffers. */
 169                         status = -EIO;
 170                         put_bh(bh);
 171                         bhs[i - 1] = NULL;
 172                 }
 173         }
 174
 175 bail:
 176         return status;
 177 }
 178
 179 int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr,
 180                       struct buffer_head *bhs[], int flags,
 181                       int (*validate)(struct super_block *sb,
 182                                       struct buffer_head *bh))
 183 {
 184         int status = 0;
 185         int i, ignore_cache = 0;
 186         struct buffer_head *bh;
 187         struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
 188
 189         mlog_entry("(ci=%p, block=(%llu), nr=(%d), flags=%d)\n",
 190                    ci, (unsigned long long)block, nr, flags);
 191
 192         BUG_ON(!ci);
 193         BUG_ON((flags & OCFS2_BH_READAHEAD) &&
 194                (flags & OCFS2_BH_IGNORE_CACHE));
 195
 196         if (bhs == NULL) {
 197                 status = -EINVAL;
 198                 mlog_errno(status);
 199                 goto bail;
 200         }
 201
 202         if (nr < 0) {
 203                 mlog(ML_ERROR, "asked to read %d blocks!\n", nr);
 204                 status = -EINVAL;
 205                 mlog_errno(status);
 206                 goto bail;
 207         }
 208
 209         if (nr == 0) {
 210                 mlog(ML_BH_IO, "No buffers will be read!\n");
 211                 status = 0;
 212                 goto bail;
 213         }
 214
 215         ocfs2_metadata_cache_io_lock(ci);
 216         for (i = 0 ; i < nr ; i++) {
 217                 if (bhs[i] == NULL) {
 218                         bhs[i] = sb_getblk(sb, block++);
 219                         if (bhs[i] == NULL) {
 220                                 ocfs2_metadata_cache_io_unlock(ci);
 221                                 status = -EIO;
 222                                 mlog_errno(status);
 223                                 goto bail;
 224                         }
 225                 }
 226                 bh = bhs[i];
 227                 ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE);
 228
 229                 /* There are three read-ahead cases here which we need to
 230                  * be concerned with. All three assume a buffer has
 231                  * previously been submitted with OCFS2_BH_READAHEAD
 232                  * and it hasn't yet completed I/O.
 233                  *
 234                  * 1) The current request is sync to disk. This rarely
 235                  *    happens these days, and never when performance
 236                  *    matters - the code can just wait on the buffer
 237                  *    lock and re-submit.
 238                  *
 239                  * 2) The current request is cached, but not
 240                  *    readahead. ocfs2_buffer_uptodate() will return
 241                  *    false anyway, so we'll wind up waiting on the
 242                  *    buffer lock to do I/O. We re-check the request
 243                  *    with after getting the lock to avoid a re-submit.
 244                  *
 245                  * 3) The current request is readahead (and so must
 246                  *    also be a caching one). We short circuit if the
 247                  *    buffer is locked (under I/O) and if it's in the
 248                  *    uptodate cache. The re-check from #2 catches the
 249                  *    case that the previous read-ahead completes just
 250                  *    before our is-it-in-flight check.
 251                  */
 252
 253                 if (!ignore_cache && !ocfs2_buffer_uptodate(ci, bh)) {
 254                         mlog(ML_UPTODATE,
 255                              "bh (%llu), owner %llu not uptodate\n",
 256                              (unsigned long long)bh->b_blocknr,
 257                              (unsigned long long)ocfs2_metadata_cache_owner(ci));
 258                         /* We're using ignore_cache here to say
 259                          * "go to disk" */
 260                         ignore_cache = 1;
 261                 }
 262
 263                 if (buffer_jbd(bh)) {
 264                         if (ignore_cache)
 265                                 mlog(ML_BH_IO, "trying to sync read a jbd "
 266                                                "managed bh (blocknr = %llu)\n",
 267                                      (unsigned long long)bh->b_blocknr);
 268                         continue;
 269                 }
 270
 271                 if (ignore_cache) {
 272                         if (buffer_dirty(bh)) {
 273                                 /* This should probably be a BUG, or
 274                                  * at least return an error. */
 275                                 mlog(ML_BH_IO, "asking me to sync read a dirty "
 276                                                "buffer! (blocknr = %llu)\n",
 277                                      (unsigned long long)bh->b_blocknr);
 278                                 continue;
 279                         }
 280
 281                         /* A read-ahead request was made - if the
 282                          * buffer is already under read-ahead from a
 283                          * previously submitted request than we are
 284                          * done here. */
 285                         if ((flags & OCFS2_BH_READAHEAD)
 286                             && ocfs2_buffer_read_ahead(ci, bh))
 287                                 continue;
 288
 289                         lock_buffer(bh);
 290                         if (buffer_jbd(bh)) {
 291 #ifdef CATCH_BH_JBD_RACES
 292                                 mlog(ML_ERROR, "block %llu had the JBD bit set "
 293                                                "while I was in lock_buffer!",
 294                                      (unsigned long long)bh->b_blocknr);
 295                                 BUG();
 296 #else
 297                                 unlock_buffer(bh);
 298                                 continue;
 299 #endif
 300                         }
 301
 302                         /* Re-check ocfs2_buffer_uptodate() as a
 303                          * previously read-ahead buffer may have
 304                          * completed I/O while we were waiting for the
 305                          * buffer lock. */
 306                         if (!(flags & OCFS2_BH_IGNORE_CACHE)
 307                             && !(flags & OCFS2_BH_READAHEAD)
 308                             && ocfs2_buffer_uptodate(ci, bh)) {
 309                                 unlock_buffer(bh);
 310                                 continue;
 311                         }
 312
 313                         clear_buffer_uptodate(bh);
 314                         get_bh(bh); /* for end_buffer_read_sync() */
 315                         if (validate)
 316                                 set_buffer_needs_validate(bh);
 317                         bh->b_end_io = end_buffer_read_sync;
 318                         submit_bh(READ, bh);
 319                         continue;
 320                 }
 321         }
 322
 323         status = 0;
 324
 325         for (i = (nr - 1); i >= 0; i--) {
 326                 bh = bhs[i];
 327
 328                 if (!(flags & OCFS2_BH_READAHEAD)) {
 329                         /* We know this can't have changed as we hold the
 330                          * owner sem. Avoid doing any work on the bh if the
 331                          * journal has it. */
 332                         if (!buffer_jbd(bh))
 333                                 wait_on_buffer(bh);
 334
 335                         if (!buffer_uptodate(bh)) {
 336                                 /* Status won't be cleared from here on out,
 337                                  * so we can safely record this and loop back
 338                                  * to cleanup the other buffers. Don't need to
 339                                  * remove the clustered uptodate information
 340                                  * for this bh as it's not marked locally
 341                                  * uptodate. */
 342                                 status = -EIO;
 343                                 put_bh(bh);
 344                                 bhs[i] = NULL;
 345                                 continue;
 346                         }
 347
 348                         if (buffer_needs_validate(bh)) {
 349                                 /* We never set NeedsValidate if the
 350                                  * buffer was held by the journal, so
 351                                  * that better not have changed */
 352                                 BUG_ON(buffer_jbd(bh));
 353                                 clear_buffer_needs_validate(bh);
 354                                 status = validate(sb, bh);
 355                                 if (status) {
 356                                         put_bh(bh);
 357                                         bhs[i] = NULL;
 358                                         continue;
 359                                 }
 360                         }
 361                 }
 362
 363                 /* Always set the buffer in the cache, even if it was
 364                  * a forced read, or read-ahead which hasn't yet
 365                  * completed. */
 366                 ocfs2_set_buffer_uptodate(ci, bh);
 367         }
 368         ocfs2_metadata_cache_io_unlock(ci);
 369
 370         mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s, flags=0x%x\n",
 371              (unsigned long long)block, nr,
 372              ((flags & OCFS2_BH_IGNORE_CACHE) || ignore_cache) ? "no" : "yes",
 373              flags);
 374
 375 bail:
 376
 377         mlog_exit(status);
 378         return status;
 379 }
 380
 381 /* Check whether the blkno is the super block or one of the backups. */
 382 static void ocfs2_check_super_or_backup(struct super_block *sb,
 383                                         sector_t blkno)
 384 {
 385         int i;
 386         u64 backup_blkno;
 387
 388         if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
 389                 return;
 390
 391         for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
 392                 backup_blkno = ocfs2_backup_super_blkno(sb, i);
 393                 if (backup_blkno == blkno)
 394                         return;
 395         }
 396
 397         BUG();
 398 }
 399
 400 /*
 401  * Write super block and backups doesn't need to collaborate with journal,
 402  * so we don't need to lock ip_io_mutex and ci doesn't need to bea passed
 403  * into this function.
 404  */
 405 int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
 406                                 struct buffer_head *bh)
 407 {
 408         int ret = 0;
 409         struct ocfs2_dinode *di = (struct ocfs2_dinode *)bh->b_data;
 410
 411         mlog_entry_void();
 412
 413         BUG_ON(buffer_jbd(bh));
 414         ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
 415
 416         if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
 417                 ret = -EROFS;
 418                 goto out;
 419         }
 420
 421         lock_buffer(bh);
 422         set_buffer_uptodate(bh);
 423
 424         /* remove from dirty list before I/O. */
 425         clear_buffer_dirty(bh);
 426
 427         get_bh(bh); /* for end_buffer_write_sync() */
 428         bh->b_end_io = end_buffer_write_sync;
 429         ocfs2_compute_meta_ecc(osb->sb, bh->b_data, &di->i_check);
 430         submit_bh(WRITE, bh);
 431
 432         wait_on_buffer(bh);
 433
 434         if (!buffer_uptodate(bh)) {
 435                 ret = -EIO;
 436                 put_bh(bh);
 437         }
 438
 439 out:
 440         mlog_exit(ret);
 441         return ret;
 442 }