git.oblomov.eu Git - linux-2.6/blob - 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/slab.h>
  29 #include <linux/highmem.h>
  30
  31 #include <cluster/masklog.h>
  32
  33 #include "ocfs2.h"
  34
  35 #include "alloc.h"
  36 #include "inode.h"
  37 #include "journal.h"
  38 #include "uptodate.h"
  39
  40 #include "buffer_head_io.h"
  41
  42 /*
  43  * Bits on bh->b_state used by ocfs2.
  44  *
  45  * These MUST be after the JBD2 bits.  Hence, we use BH_JBDPrivateStart.
  46  */
  47 enum ocfs2_state_bits {
  48         BH_NeedsValidate = BH_JBDPrivateStart,
  49 };
  50
  51 /* Expand the magic b_state functions */
  52 BUFFER_FNS(NeedsValidate, needs_validate);
  53
  54 int ocfs2_write_block(struct ocfs2_super *osb, struct buffer_head *bh,
  55                       struct inode *inode)
  56 {
  57         int ret = 0;
  58
  59         mlog_entry("(bh->b_blocknr = %llu, inode=%p)\n",
  60                    (unsigned long long)bh->b_blocknr, inode);
  61
  62         BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO);
  63         BUG_ON(buffer_jbd(bh));
  64
  65         /* No need to check for a soft readonly file system here. non
  66          * journalled writes are only ever done on system files which
  67          * can get modified during recovery even if read-only. */
  68         if (ocfs2_is_hard_readonly(osb)) {
  69                 ret = -EROFS;
  70                 goto out;
  71         }
  72
  73         mutex_lock(&OCFS2_I(inode)->ip_io_mutex);
  74
  75         lock_buffer(bh);
  76         set_buffer_uptodate(bh);
  77
  78         /* remove from dirty list before I/O. */
  79         clear_buffer_dirty(bh);
  80
  81         get_bh(bh); /* for end_buffer_write_sync() */
  82         bh->b_end_io = end_buffer_write_sync;
  83         submit_bh(WRITE, bh);
  84
  85         wait_on_buffer(bh);
  86
  87         if (buffer_uptodate(bh)) {
  88                 ocfs2_set_buffer_uptodate(inode, bh);
  89         } else {
  90                 /* We don't need to remove the clustered uptodate
  91                  * information for this bh as it's not marked locally
  92                  * uptodate. */
  93                 ret = -EIO;
  94                 put_bh(bh);
  95         }
  96
  97         mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
  98 out:
  99         mlog_exit(ret);
 100         return ret;
 101 }
 102
 103 int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
 104                            unsigned int nr, struct buffer_head *bhs[])
 105 {
 106         int status = 0;
 107         unsigned int i;
 108         struct buffer_head *bh;
 109
 110         if (!nr) {
 111                 mlog(ML_BH_IO, "No buffers will be read!\n");
 112                 goto bail;
 113         }
 114
 115         for (i = 0 ; i < nr ; i++) {
 116                 if (bhs[i] == NULL) {
 117                         bhs[i] = sb_getblk(osb->sb, block++);
 118                         if (bhs[i] == NULL) {
 119                                 status = -EIO;
 120                                 mlog_errno(status);
 121                                 goto bail;
 122                         }
 123                 }
 124                 bh = bhs[i];
 125
 126                 if (buffer_jbd(bh)) {
 127                         mlog(ML_BH_IO,
 128                              "trying to sync read a jbd "
 129                              "managed bh (blocknr = %llu), skipping\n",
 130                              (unsigned long long)bh->b_blocknr);
 131                         continue;
 132                 }
 133
 134                 if (buffer_dirty(bh)) {
 135                         /* This should probably be a BUG, or
 136                          * at least return an error. */
 137                         mlog(ML_ERROR,
 138                              "trying to sync read a dirty "
 139                              "buffer! (blocknr = %llu), skipping\n",
 140                              (unsigned long long)bh->b_blocknr);
 141                         continue;
 142                 }
 143
 144                 lock_buffer(bh);
 145                 if (buffer_jbd(bh)) {
 146                         mlog(ML_ERROR,
 147                              "block %llu had the JBD bit set "
 148                              "while I was in lock_buffer!",
 149                              (unsigned long long)bh->b_blocknr);
 150                         BUG();
 151                 }
 152
 153                 clear_buffer_uptodate(bh);
 154                 get_bh(bh); /* for end_buffer_read_sync() */
 155                 bh->b_end_io = end_buffer_read_sync;
 156                 submit_bh(READ, bh);
 157         }
 158
 159         for (i = nr; i > 0; i--) {
 160                 bh = bhs[i - 1];
 161
 162                 /* No need to wait on the buffer if it's managed by JBD. */
 163                 if (!buffer_jbd(bh))
 164                         wait_on_buffer(bh);
 165
 166                 if (!buffer_uptodate(bh)) {
 167                         /* Status won't be cleared from here on out,
 168                          * so we can safely record this and loop back
 169                          * to cleanup the other buffers. */
 170                         status = -EIO;
 171                         put_bh(bh);
 172                         bhs[i - 1] = NULL;
 173                 }
 174         }
 175
 176 bail:
 177         return status;
 178 }
 179
 180 int ocfs2_read_blocks(struct inode *inode, u64 block, int nr,
 181                       struct buffer_head *bhs[], int flags,
 182                       int (*validate)(struct super_block *sb,
 183                                       struct buffer_head *bh))
 184 {
 185         int status = 0;
 186         int i, ignore_cache = 0;
 187         struct buffer_head *bh;
 188
 189         mlog_entry("(inode=%p, block=(%llu), nr=(%d), flags=%d)\n",
 190                    inode, (unsigned long long)block, nr, flags);
 191
 192         BUG_ON(!inode);
 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         mutex_lock(&OCFS2_I(inode)->ip_io_mutex);
 216         for (i = 0 ; i < nr ; i++) {
 217                 if (bhs[i] == NULL) {
 218                         bhs[i] = sb_getblk(inode->i_sb, block++);
 219                         if (bhs[i] == NULL) {
 220                                 mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
 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(inode, bh)) {
 254                         mlog(ML_UPTODATE,
 255                              "bh (%llu), inode %llu not uptodate\n",
 256                              (unsigned long long)bh->b_blocknr,
 257                              (unsigned long long)OCFS2_I(inode)->ip_blkno);
 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(inode, 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(inode, 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                          * inode 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(inode->i_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(inode, bh);
 367         }
 368         mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
 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 inode 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
 410         mlog_entry_void();
 411
 412         BUG_ON(buffer_jbd(bh));
 413         ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
 414
 415         if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
 416                 ret = -EROFS;
 417                 goto out;
 418         }
 419
 420         lock_buffer(bh);
 421         set_buffer_uptodate(bh);
 422
 423         /* remove from dirty list before I/O. */
 424         clear_buffer_dirty(bh);
 425
 426         get_bh(bh); /* for end_buffer_write_sync() */
 427         bh->b_end_io = end_buffer_write_sync;
 428         submit_bh(WRITE, bh);
 429
 430         wait_on_buffer(bh);
 431
 432         if (!buffer_uptodate(bh)) {
 433                 ret = -EIO;
 434                 put_bh(bh);
 435         }
 436
 437 out:
 438         mlog_exit(ret);
 439         return ret;
 440 }