kernel/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(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                 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                         mlog(ML_ERROR,
 143                              "block %llu had the JBD bit set "
 144                              "while I was in lock_buffer!",
 145                              (unsigned long long)bh->b_blocknr);
 146                         BUG();
 147                 }
 148
 149                 clear_buffer_uptodate(bh);
 150                 get_bh(bh); /* for end_buffer_read_sync() */
 151                 bh->b_end_io = end_buffer_read_sync;
 152                 submit_bh(READ, bh);
 153         }
 154
 155         for (i = nr; i > 0; i--) {
 156                 bh = bhs[i - 1];
 157
 158                 /* No need to wait on the buffer if it's managed by JBD. */
 159                 if (!buffer_jbd(bh))
 160                         wait_on_buffer(bh);
 161
 162                 if (!buffer_uptodate(bh)) {
 163                         /* Status won't be cleared from here on out,
 164                          * so we can safely record this and loop back
 165                          * to cleanup the other buffers. */
 166                         status = -EIO;
 167                         put_bh(bh);
 168                         bhs[i - 1] = NULL;
 169                 }
 170         }
 171
 172 bail:
 173         return status;
 174 }
 175
 176 int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr,
 177                       struct buffer_head *bhs[], int flags,
 178                       int (*validate)(struct super_block *sb,
 179                                       struct buffer_head *bh))
 180 {
 181         int status = 0;
 182         int i, ignore_cache = 0;
 183         struct buffer_head *bh;
 184         struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
 185
 186         trace_ocfs2_read_blocks_begin(ci, (unsigned long long)block, nr, flags);
 187
 188         BUG_ON(!ci);
 189         BUG_ON((flags & OCFS2_BH_READAHEAD) &&
 190                (flags & OCFS2_BH_IGNORE_CACHE));
 191
 192         if (bhs == NULL) {
 193                 status = -EINVAL;
 194                 mlog_errno(status);
 195                 goto bail;
 196         }
 197
 198         if (nr < 0) {
 199                 mlog(ML_ERROR, "asked to read %d blocks!\n", nr);
 200                 status = -EINVAL;
 201                 mlog_errno(status);
 202                 goto bail;
 203         }
 204
 205         if (nr == 0) {
 206                 status = 0;
 207                 goto bail;
 208         }
 209
 210         ocfs2_metadata_cache_io_lock(ci);
 211         for (i = 0 ; i < nr ; i++) {
 212                 if (bhs[i] == NULL) {
 213                         bhs[i] = sb_getblk(sb, block++);
 214                         if (bhs[i] == NULL) {
 215                                 ocfs2_metadata_cache_io_unlock(ci);
 216                                 status = -ENOMEM;
 217                                 mlog_errno(status);
 218                                 goto bail;
 219                         }
 220                 }
 221                 bh = bhs[i];
 222                 ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE);
 223
 224                 /* There are three read-ahead cases here which we need to
 225                  * be concerned with. All three assume a buffer has
 226                  * previously been submitted with OCFS2_BH_READAHEAD
 227                  * and it hasn't yet completed I/O.
 228                  *
 229                  * 1) The current request is sync to disk. This rarely
 230                  *    happens these days, and never when performance
 231                  *    matters - the code can just wait on the buffer
 232                  *    lock and re-submit.
 233                  *
 234                  * 2) The current request is cached, but not
 235                  *    readahead. ocfs2_buffer_uptodate() will return
 236                  *    false anyway, so we'll wind up waiting on the
 237                  *    buffer lock to do I/O. We re-check the request
 238                  *    with after getting the lock to avoid a re-submit.
 239                  *
 240                  * 3) The current request is readahead (and so must
 241                  *    also be a caching one). We short circuit if the
 242                  *    buffer is locked (under I/O) and if it's in the
 243                  *    uptodate cache. The re-check from #2 catches the
 244                  *    case that the previous read-ahead completes just
 245                  *    before our is-it-in-flight check.
 246                  */
 247
 248                 if (!ignore_cache && !ocfs2_buffer_uptodate(ci, bh)) {
 249                         trace_ocfs2_read_blocks_from_disk(
 250                              (unsigned long long)bh->b_blocknr,
 251                              (unsigned long long)ocfs2_metadata_cache_owner(ci));
 252                         /* We're using ignore_cache here to say
 253                          * "go to disk" */
 254                         ignore_cache = 1;
 255                 }
 256
 257                 trace_ocfs2_read_blocks_bh((unsigned long long)bh->b_blocknr,
 258                         ignore_cache, buffer_jbd(bh), buffer_dirty(bh));
 259
 260                 if (buffer_jbd(bh)) {
 261                         continue;
 262                 }
 263
 264                 if (ignore_cache) {
 265                         if (buffer_dirty(bh)) {
 266                                 /* This should probably be a BUG, or
 267                                  * at least return an error. */
 268                                 continue;
 269                         }
 270
 271                         /* A read-ahead request was made - if the
 272                          * buffer is already under read-ahead from a
 273                          * previously submitted request than we are
 274                          * done here. */
 275                         if ((flags & OCFS2_BH_READAHEAD)
 276                             && ocfs2_buffer_read_ahead(ci, bh))
 277                                 continue;
 278
 279                         lock_buffer(bh);
 280                         if (buffer_jbd(bh)) {
 281 #ifdef CATCH_BH_JBD_RACES
 282                                 mlog(ML_ERROR, "block %llu had the JBD bit set "
 283                                                "while I was in lock_buffer!",
 284                                      (unsigned long long)bh->b_blocknr);
 285                                 BUG();
 286 #else
 287                                 unlock_buffer(bh);
 288                                 continue;
 289 #endif
 290                         }
 291
 292                         /* Re-check ocfs2_buffer_uptodate() as a
 293                          * previously read-ahead buffer may have
 294                          * completed I/O while we were waiting for the
 295                          * buffer lock. */
 296                         if (!(flags & OCFS2_BH_IGNORE_CACHE)
 297                             && !(flags & OCFS2_BH_READAHEAD)
 298                             && ocfs2_buffer_uptodate(ci, bh)) {
 299                                 unlock_buffer(bh);
 300                                 continue;
 301                         }
 302
 303                         clear_buffer_uptodate(bh);
 304                         get_bh(bh); /* for end_buffer_read_sync() */
 305                         if (validate)
 306                                 set_buffer_needs_validate(bh);
 307                         bh->b_end_io = end_buffer_read_sync;
 308                         submit_bh(READ, bh);
 309                         continue;
 310                 }
 311         }
 312
 313         status = 0;
 314
 315         for (i = (nr - 1); i >= 0; i--) {
 316                 bh = bhs[i];
 317
 318                 if (!(flags & OCFS2_BH_READAHEAD)) {
 319                         /* We know this can't have changed as we hold the
 320                          * owner sem. Avoid doing any work on the bh if the
 321                          * journal has it. */
 322                         if (!buffer_jbd(bh))
 323                                 wait_on_buffer(bh);
 324
 325                         if (!buffer_uptodate(bh)) {
 326                                 /* Status won't be cleared from here on out,
 327                                  * so we can safely record this and loop back
 328                                  * to cleanup the other buffers. Don't need to
 329                                  * remove the clustered uptodate information
 330                                  * for this bh as it's not marked locally
 331                                  * uptodate. */
 332                                 status = -EIO;
 333                                 put_bh(bh);
 334                                 bhs[i] = NULL;
 335                                 continue;
 336                         }
 337
 338                         if (buffer_needs_validate(bh)) {
 339                                 /* We never set NeedsValidate if the
 340                                  * buffer was held by the journal, so
 341                                  * that better not have changed */
 342                                 BUG_ON(buffer_jbd(bh));
 343                                 clear_buffer_needs_validate(bh);
 344                                 status = validate(sb, bh);
 345                                 if (status) {
 346                                         put_bh(bh);
 347                                         bhs[i] = NULL;
 348                                         continue;
 349                                 }
 350                         }
 351                 }
 352
 353                 /* Always set the buffer in the cache, even if it was
 354                  * a forced read, or read-ahead which hasn't yet
 355                  * completed. */
 356                 ocfs2_set_buffer_uptodate(ci, bh);
 357         }
 358         ocfs2_metadata_cache_io_unlock(ci);
 359
 360         trace_ocfs2_read_blocks_end((unsigned long long)block, nr,
 361                                     flags, ignore_cache);
 362
 363 bail:
 364
 365         return status;
 366 }
 367
 368 /* Check whether the blkno is the super block or one of the backups. */
 369 static void ocfs2_check_super_or_backup(struct super_block *sb,
 370                                         sector_t blkno)
 371 {
 372         int i;
 373         u64 backup_blkno;
 374
 375         if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
 376                 return;
 377
 378         for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
 379                 backup_blkno = ocfs2_backup_super_blkno(sb, i);
 380                 if (backup_blkno == blkno)
 381                         return;
 382         }
 383
 384         BUG();
 385 }
 386
 387 /*
 388  * Write super block and backups doesn't need to collaborate with journal,
 389  * so we don't need to lock ip_io_mutex and ci doesn't need to bea passed
 390  * into this function.
 391  */
 392 int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
 393                                 struct buffer_head *bh)
 394 {
 395         int ret = 0;
 396         struct ocfs2_dinode *di = (struct ocfs2_dinode *)bh->b_data;
 397
 398         BUG_ON(buffer_jbd(bh));
 399         ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
 400
 401         if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
 402                 ret = -EROFS;
 403                 mlog_errno(ret);
 404                 goto out;
 405         }
 406
 407         lock_buffer(bh);
 408         set_buffer_uptodate(bh);
 409
 410         /* remove from dirty list before I/O. */
 411         clear_buffer_dirty(bh);
 412
 413         get_bh(bh); /* for end_buffer_write_sync() */
 414         bh->b_end_io = end_buffer_write_sync;
 415         ocfs2_compute_meta_ecc(osb->sb, bh->b_data, &di->i_check);
 416         submit_bh(WRITE, bh);
 417
 418         wait_on_buffer(bh);
 419
 420         if (!buffer_uptodate(bh)) {
 421                 ret = -EIO;
 422                 mlog_errno(ret);
 423         }
 424
 425 out:
 426         return ret;
 427 }