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 #include "buffer_head_io.h"
  39 #include "ocfs2_trace.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         trace_ocfs2_write_block((unsigned long long)bh->b_blocknr, ci);
  59
  60         BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO);
  61         BUG_ON(buffer_jbd(bh));
  62
  63         /* No need to check for a soft readonly file system here. non
  64          * journalled writes are only ever done on system files which
  65          * can get modified during recovery even if read-only. */
  66         if (ocfs2_is_hard_readonly(osb)) {
  67                 ret = -EROFS;
  68                 mlog_errno(ret);
  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(REQ_OP_WRITE, 0, 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                 mlog_errno(ret);
  94         }
  95
  96         ocfs2_metadata_cache_io_unlock(ci);
  97 out:
  98         return ret;
  99 }
 100
 101 int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
 102                            unsigned int nr, struct buffer_head *bhs[])
 103 {
 104         int status = 0;
 105         unsigned int i;
 106         struct buffer_head *bh;
 107
 108         trace_ocfs2_read_blocks_sync((unsigned long long)block, nr);
 109
 110         if (!nr)
 111                 goto bail;
 112
 113         for (i = 0 ; i < nr ; i++) {
 114                 if (bhs[i] == NULL) {
 115                         bhs[i] = sb_getblk(osb->sb, block++);
 116                         if (bhs[i] == NULL) {
 117                                 status = -ENOMEM;
 118                                 mlog_errno(status);
 119                                 goto bail;
 120                         }
 121                 }
 122                 bh = bhs[i];
 123
 124                 if (buffer_jbd(bh)) {
 125                         trace_ocfs2_read_blocks_sync_jbd(
 126                                         (unsigned long long)bh->b_blocknr);
 127                         continue;
 128                 }
 129
 130                 if (buffer_dirty(bh)) {
 131                         /* This should probably be a BUG, or
 132                          * at least return an error. */
 133                         mlog(ML_ERROR,
 134                              "trying to sync read a dirty "
 135                              "buffer! (blocknr = %llu), skipping\n",
 136                              (unsigned long long)bh->b_blocknr);
 137                         continue;
 138                 }
 139
 140                 lock_buffer(bh);
 141                 if (buffer_jbd(bh)) {
 142 #ifdef CATCH_BH_JBD_RACES
 143                         mlog(ML_ERROR,
 144                              "block %llu had the JBD bit set "
 145                              "while I was in lock_buffer!",
 146                              (unsigned long long)bh->b_blocknr);
 147                         BUG();
 148 #else
 149                         unlock_buffer(bh);
 150                         continue;
 151 #endif
 152                 }
 153
 154                 clear_buffer_uptodate(bh);
 155                 get_bh(bh); /* for end_buffer_read_sync() */
 156                 bh->b_end_io = end_buffer_read_sync;
 157                 submit_bh(REQ_OP_READ, 0, bh);
 158         }
 159
 160         for (i = nr; i > 0; i--) {
 161                 bh = bhs[i - 1];
 162
 163                 /* No need to wait on the buffer if it's managed by JBD. */
 164                 if (!buffer_jbd(bh))
 165                         wait_on_buffer(bh);
 166
 167                 if (!buffer_uptodate(bh)) {
 168                         /* Status won't be cleared from here on out,
 169                          * so we can safely record this and loop back
 170                          * to cleanup the other buffers. */
 171                         status = -EIO;
 172                         put_bh(bh);
 173                         bhs[i - 1] = NULL;
 174                 }
 175         }
 176
 177 bail:
 178         return status;
 179 }
 180
 181 int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr,
 182                       struct buffer_head *bhs[], int flags,
 183                       int (*validate)(struct super_block *sb,
 184                                       struct buffer_head *bh))
 185 {
 186         int status = 0;
 187         int i, ignore_cache = 0;
 188         struct buffer_head *bh;
 189         struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
 190
 191         trace_ocfs2_read_blocks_begin(ci, (unsigned long long)block, nr, flags);
 192
 193         BUG_ON(!ci);
 194         BUG_ON((flags & OCFS2_BH_READAHEAD) &&
 195                (flags & OCFS2_BH_IGNORE_CACHE));
 196
 197         if (bhs == NULL) {
 198                 status = -EINVAL;
 199                 mlog_errno(status);
 200                 goto bail;
 201         }
 202
 203         if (nr < 0) {
 204                 mlog(ML_ERROR, "asked to read %d blocks!\n", nr);
 205                 status = -EINVAL;
 206                 mlog_errno(status);
 207                 goto bail;
 208         }
 209
 210         if (nr == 0) {
 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 = -ENOMEM;
 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                         trace_ocfs2_read_blocks_from_disk(
 255                              (unsigned long long)bh->b_blocknr,
 256                              (unsigned long long)ocfs2_metadata_cache_owner(ci));
 257                         /* We're using ignore_cache here to say
 258                          * "go to disk" */
 259                         ignore_cache = 1;
 260                 }
 261
 262                 trace_ocfs2_read_blocks_bh((unsigned long long)bh->b_blocknr,
 263                         ignore_cache, buffer_jbd(bh), buffer_dirty(bh));
 264
 265                 if (buffer_jbd(bh)) {
 266                         continue;
 267                 }
 268
 269                 if (ignore_cache) {
 270                         if (buffer_dirty(bh)) {
 271                                 /* This should probably be a BUG, or
 272                                  * at least return an error. */
 273                                 continue;
 274                         }
 275
 276                         /* A read-ahead request was made - if the
 277                          * buffer is already under read-ahead from a
 278                          * previously submitted request than we are
 279                          * done here. */
 280                         if ((flags & OCFS2_BH_READAHEAD)
 281                             && ocfs2_buffer_read_ahead(ci, bh))
 282                                 continue;
 283
 284                         lock_buffer(bh);
 285                         if (buffer_jbd(bh)) {
 286 #ifdef CATCH_BH_JBD_RACES
 287                                 mlog(ML_ERROR, "block %llu had the JBD bit set "
 288                                                "while I was in lock_buffer!",
 289                                      (unsigned long long)bh->b_blocknr);
 290                                 BUG();
 291 #else
 292                                 unlock_buffer(bh);
 293                                 continue;
 294 #endif
 295                         }
 296
 297                         /* Re-check ocfs2_buffer_uptodate() as a
 298                          * previously read-ahead buffer may have
 299                          * completed I/O while we were waiting for the
 300                          * buffer lock. */
 301                         if (!(flags & OCFS2_BH_IGNORE_CACHE)
 302                             && !(flags & OCFS2_BH_READAHEAD)
 303                             && ocfs2_buffer_uptodate(ci, bh)) {
 304                                 unlock_buffer(bh);
 305                                 continue;
 306                         }
 307
 308                         clear_buffer_uptodate(bh);
 309                         get_bh(bh); /* for end_buffer_read_sync() */
 310                         if (validate)
 311                                 set_buffer_needs_validate(bh);
 312                         bh->b_end_io = end_buffer_read_sync;
 313                         submit_bh(REQ_OP_READ, 0, bh);
 314                         continue;
 315                 }
 316         }
 317
 318         status = 0;
 319
 320         for (i = (nr - 1); i >= 0; i--) {
 321                 bh = bhs[i];
 322
 323                 if (!(flags & OCFS2_BH_READAHEAD)) {
 324                         if (status) {
 325                                 /* Clear the rest of the buffers on error */
 326                                 put_bh(bh);
 327                                 bhs[i] = NULL;
 328                                 continue;
 329                         }
 330                         /* We know this can't have changed as we hold the
 331                          * owner sem. Avoid doing any work on the bh if the
 332                          * journal has it. */
 333                         if (!buffer_jbd(bh))
 334                                 wait_on_buffer(bh);
 335
 336                         if (!buffer_uptodate(bh)) {
 337                                 /* Status won't be cleared from here on out,
 338                                  * so we can safely record this and loop back
 339                                  * to cleanup the other buffers. Don't need to
 340                                  * remove the clustered uptodate information
 341                                  * for this bh as it's not marked locally
 342                                  * uptodate. */
 343                                 status = -EIO;
 344                                 put_bh(bh);
 345                                 bhs[i] = NULL;
 346                                 continue;
 347                         }
 348
 349                         if (buffer_needs_validate(bh)) {
 350                                 /* We never set NeedsValidate if the
 351                                  * buffer was held by the journal, so
 352                                  * that better not have changed */
 353                                 BUG_ON(buffer_jbd(bh));
 354                                 clear_buffer_needs_validate(bh);
 355                                 status = validate(sb, bh);
 356                                 if (status) {
 357                                         put_bh(bh);
 358                                         bhs[i] = NULL;
 359                                         continue;
 360                                 }
 361                         }
 362                 }
 363
 364                 /* Always set the buffer in the cache, even if it was
 365                  * a forced read, or read-ahead which hasn't yet
 366                  * completed. */
 367                 ocfs2_set_buffer_uptodate(ci, bh);
 368         }
 369         ocfs2_metadata_cache_io_unlock(ci);
 370
 371         trace_ocfs2_read_blocks_end((unsigned long long)block, nr,
 372                                     flags, ignore_cache);
 373
 374 bail:
 375
 376         return status;
 377 }
 378
 379 /* Check whether the blkno is the super block or one of the backups. */
 380 static void ocfs2_check_super_or_backup(struct super_block *sb,
 381                                         sector_t blkno)
 382 {
 383         int i;
 384         u64 backup_blkno;
 385
 386         if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
 387                 return;
 388
 389         for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
 390                 backup_blkno = ocfs2_backup_super_blkno(sb, i);
 391                 if (backup_blkno == blkno)
 392                         return;
 393         }
 394
 395         BUG();
 396 }
 397
 398 /*
 399  * Write super block and backups doesn't need to collaborate with journal,
 400  * so we don't need to lock ip_io_mutex and ci doesn't need to bea passed
 401  * into this function.
 402  */
 403 int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
 404                                 struct buffer_head *bh)
 405 {
 406         int ret = 0;
 407         struct ocfs2_dinode *di = (struct ocfs2_dinode *)bh->b_data;
 408
 409         BUG_ON(buffer_jbd(bh));
 410         ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
 411
 412         if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
 413                 ret = -EROFS;
 414                 mlog_errno(ret);
 415                 goto out;
 416         }
 417
 418         lock_buffer(bh);
 419         set_buffer_uptodate(bh);
 420
 421         /* remove from dirty list before I/O. */
 422         clear_buffer_dirty(bh);
 423
 424         get_bh(bh); /* for end_buffer_write_sync() */
 425         bh->b_end_io = end_buffer_write_sync;
 426         ocfs2_compute_meta_ecc(osb->sb, bh->b_data, &di->i_check);
 427         submit_bh(REQ_OP_WRITE, 0, bh);
 428
 429         wait_on_buffer(bh);
 430
 431         if (!buffer_uptodate(bh)) {
 432                 ret = -EIO;
 433                 mlog_errno(ret);
 434         }
 435
 436 out:
 437         return ret;
 438 }