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 #include <linux/bio.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 #include "buffer_head_io.h"
  40 #include "ocfs2_trace.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 ocfs2_caching_info *ci)
  56 {
  57         int ret = 0;
  58
  59         trace_ocfs2_write_block((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                 mlog_errno(ret);
  70                 goto out;
  71         }
  72
  73         ocfs2_metadata_cache_io_lock(ci);
  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(REQ_OP_WRITE, 0, bh);
  84
  85         wait_on_buffer(bh);
  86
  87         if (buffer_uptodate(bh)) {
  88                 ocfs2_set_buffer_uptodate(ci, 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                 mlog_errno(ret);
  95         }
  96
  97         ocfs2_metadata_cache_io_unlock(ci);
  98 out:
  99         return ret;
 100 }
 101
 102 /* Caller must provide a bhs[] with all NULL or non-NULL entries, so it
 103  * will be easier to handle read failure.
 104  */
 105 int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
 106                            unsigned int nr, struct buffer_head *bhs[])
 107 {
 108         int status = 0;
 109         unsigned int i;
 110         struct buffer_head *bh;
 111         int new_bh = 0;
 112
 113         trace_ocfs2_read_blocks_sync((unsigned long long)block, nr);
 114
 115         if (!nr)
 116                 goto bail;
 117
 118         /* Don't put buffer head and re-assign it to NULL if it is allocated
 119          * outside since the caller can't be aware of this alternation!
 120          */
 121         new_bh = (bhs[0] == NULL);
 122
 123         for (i = 0 ; i < nr ; i++) {
 124                 if (bhs[i] == NULL) {
 125                         bhs[i] = sb_getblk(osb->sb, block++);
 126                         if (bhs[i] == NULL) {
 127                                 status = -ENOMEM;
 128                                 mlog_errno(status);
 129                                 break;
 130                         }
 131                 }
 132                 bh = bhs[i];
 133
 134                 if (buffer_jbd(bh)) {
 135                         trace_ocfs2_read_blocks_sync_jbd(
 136                                         (unsigned long long)bh->b_blocknr);
 137                         continue;
 138                 }
 139
 140                 if (buffer_dirty(bh)) {
 141                         /* This should probably be a BUG, or
 142                          * at least return an error. */
 143                         mlog(ML_ERROR,
 144                              "trying to sync read a dirty "
 145                              "buffer! (blocknr = %llu), skipping\n",
 146                              (unsigned long long)bh->b_blocknr);
 147                         continue;
 148                 }
 149
 150                 lock_buffer(bh);
 151                 if (buffer_jbd(bh)) {
 152 #ifdef CATCH_BH_JBD_RACES
 153                         mlog(ML_ERROR,
 154                              "block %llu had the JBD bit set "
 155                              "while I was in lock_buffer!",
 156                              (unsigned long long)bh->b_blocknr);
 157                         BUG();
 158 #else
 159                         unlock_buffer(bh);
 160                         continue;
 161 #endif
 162                 }
 163
 164                 get_bh(bh); /* for end_buffer_read_sync() */
 165                 bh->b_end_io = end_buffer_read_sync;
 166                 submit_bh(REQ_OP_READ, 0, bh);
 167         }
 168
 169 read_failure:
 170         for (i = nr; i > 0; i--) {
 171                 bh = bhs[i - 1];
 172
 173                 if (unlikely(status)) {
 174                         if (new_bh && bh) {
 175                                 /* If middle bh fails, let previous bh
 176                                  * finish its read and then put it to
 177                                  * aovoid bh leak
 178                                  */
 179                                 if (!buffer_jbd(bh))
 180                                         wait_on_buffer(bh);
 181                                 put_bh(bh);
 182                                 bhs[i - 1] = NULL;
 183                         } else if (bh && buffer_uptodate(bh)) {
 184                                 clear_buffer_uptodate(bh);
 185                         }
 186                         continue;
 187                 }
 188
 189                 /* No need to wait on the buffer if it's managed by JBD. */
 190                 if (!buffer_jbd(bh))
 191                         wait_on_buffer(bh);
 192
 193                 if (!buffer_uptodate(bh)) {
 194                         /* Status won't be cleared from here on out,
 195                          * so we can safely record this and loop back
 196                          * to cleanup the other buffers. */
 197                         status = -EIO;
 198                         goto read_failure;
 199                 }
 200         }
 201
 202 bail:
 203         return status;
 204 }
 205
 206 /* Caller must provide a bhs[] with all NULL or non-NULL entries, so it
 207  * will be easier to handle read failure.
 208  */
 209 int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr,
 210                       struct buffer_head *bhs[], int flags,
 211                       int (*validate)(struct super_block *sb,
 212                                       struct buffer_head *bh))
 213 {
 214         int status = 0;
 215         int i, ignore_cache = 0;
 216         struct buffer_head *bh;
 217         struct super_block *sb = ocfs2_metadata_cache_get_super(ci);
 218         int new_bh = 0;
 219
 220         trace_ocfs2_read_blocks_begin(ci, (unsigned long long)block, nr, flags);
 221
 222         BUG_ON(!ci);
 223         BUG_ON((flags & OCFS2_BH_READAHEAD) &&
 224                (flags & OCFS2_BH_IGNORE_CACHE));
 225
 226         if (bhs == NULL) {
 227                 status = -EINVAL;
 228                 mlog_errno(status);
 229                 goto bail;
 230         }
 231
 232         if (nr < 0) {
 233                 mlog(ML_ERROR, "asked to read %d blocks!\n", nr);
 234                 status = -EINVAL;
 235                 mlog_errno(status);
 236                 goto bail;
 237         }
 238
 239         if (nr == 0) {
 240                 status = 0;
 241                 goto bail;
 242         }
 243
 244         /* Don't put buffer head and re-assign it to NULL if it is allocated
 245          * outside since the caller can't be aware of this alternation!
 246          */
 247         new_bh = (bhs[0] == NULL);
 248
 249         ocfs2_metadata_cache_io_lock(ci);
 250         for (i = 0 ; i < nr ; i++) {
 251                 if (bhs[i] == NULL) {
 252                         bhs[i] = sb_getblk(sb, block++);
 253                         if (bhs[i] == NULL) {
 254                                 ocfs2_metadata_cache_io_unlock(ci);
 255                                 status = -ENOMEM;
 256                                 mlog_errno(status);
 257                                 /* Don't forget to put previous bh! */
 258                                 break;
 259                         }
 260                 }
 261                 bh = bhs[i];
 262                 ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE);
 263
 264                 /* There are three read-ahead cases here which we need to
 265                  * be concerned with. All three assume a buffer has
 266                  * previously been submitted with OCFS2_BH_READAHEAD
 267                  * and it hasn't yet completed I/O.
 268                  *
 269                  * 1) The current request is sync to disk. This rarely
 270                  *    happens these days, and never when performance
 271                  *    matters - the code can just wait on the buffer
 272                  *    lock and re-submit.
 273                  *
 274                  * 2) The current request is cached, but not
 275                  *    readahead. ocfs2_buffer_uptodate() will return
 276                  *    false anyway, so we'll wind up waiting on the
 277                  *    buffer lock to do I/O. We re-check the request
 278                  *    with after getting the lock to avoid a re-submit.
 279                  *
 280                  * 3) The current request is readahead (and so must
 281                  *    also be a caching one). We short circuit if the
 282                  *    buffer is locked (under I/O) and if it's in the
 283                  *    uptodate cache. The re-check from #2 catches the
 284                  *    case that the previous read-ahead completes just
 285                  *    before our is-it-in-flight check.
 286                  */
 287
 288                 if (!ignore_cache && !ocfs2_buffer_uptodate(ci, bh)) {
 289                         trace_ocfs2_read_blocks_from_disk(
 290                              (unsigned long long)bh->b_blocknr,
 291                              (unsigned long long)ocfs2_metadata_cache_owner(ci));
 292                         /* We're using ignore_cache here to say
 293                          * "go to disk" */
 294                         ignore_cache = 1;
 295                 }
 296
 297                 trace_ocfs2_read_blocks_bh((unsigned long long)bh->b_blocknr,
 298                         ignore_cache, buffer_jbd(bh), buffer_dirty(bh));
 299
 300                 if (buffer_jbd(bh)) {
 301                         continue;
 302                 }
 303
 304                 if (ignore_cache) {
 305                         if (buffer_dirty(bh)) {
 306                                 /* This should probably be a BUG, or
 307                                  * at least return an error. */
 308                                 continue;
 309                         }
 310
 311                         /* A read-ahead request was made - if the
 312                          * buffer is already under read-ahead from a
 313                          * previously submitted request than we are
 314                          * done here. */
 315                         if ((flags & OCFS2_BH_READAHEAD)
 316                             && ocfs2_buffer_read_ahead(ci, bh))
 317                                 continue;
 318
 319                         lock_buffer(bh);
 320                         if (buffer_jbd(bh)) {
 321 #ifdef CATCH_BH_JBD_RACES
 322                                 mlog(ML_ERROR, "block %llu had the JBD bit set "
 323                                                "while I was in lock_buffer!",
 324                                      (unsigned long long)bh->b_blocknr);
 325                                 BUG();
 326 #else
 327                                 unlock_buffer(bh);
 328                                 continue;
 329 #endif
 330                         }
 331
 332                         /* Re-check ocfs2_buffer_uptodate() as a
 333                          * previously read-ahead buffer may have
 334                          * completed I/O while we were waiting for the
 335                          * buffer lock. */
 336                         if (!(flags & OCFS2_BH_IGNORE_CACHE)
 337                             && !(flags & OCFS2_BH_READAHEAD)
 338                             && ocfs2_buffer_uptodate(ci, bh)) {
 339                                 unlock_buffer(bh);
 340                                 continue;
 341                         }
 342
 343                         get_bh(bh); /* for end_buffer_read_sync() */
 344                         if (validate)
 345                                 set_buffer_needs_validate(bh);
 346                         bh->b_end_io = end_buffer_read_sync;
 347                         submit_bh(REQ_OP_READ, 0, bh);
 348                         continue;
 349                 }
 350         }
 351
 352 read_failure:
 353         for (i = (nr - 1); i >= 0; i--) {
 354                 bh = bhs[i];
 355
 356                 if (!(flags & OCFS2_BH_READAHEAD)) {
 357                         if (unlikely(status)) {
 358                                 /* Clear the buffers on error including those
 359                                  * ever succeeded in reading
 360                                  */
 361                                 if (new_bh && bh) {
 362                                         /* If middle bh fails, let previous bh
 363                                          * finish its read and then put it to
 364                                          * aovoid bh leak
 365                                          */
 366                                         if (!buffer_jbd(bh))
 367                                                 wait_on_buffer(bh);
 368                                         put_bh(bh);
 369                                         bhs[i] = NULL;
 370                                 } else if (bh && buffer_uptodate(bh)) {
 371                                         clear_buffer_uptodate(bh);
 372                                 }
 373                                 continue;
 374                         }
 375                         /* We know this can't have changed as we hold the
 376                          * owner sem. Avoid doing any work on the bh if the
 377                          * journal has it. */
 378                         if (!buffer_jbd(bh))
 379                                 wait_on_buffer(bh);
 380
 381                         if (!buffer_uptodate(bh)) {
 382                                 /* Status won't be cleared from here on out,
 383                                  * so we can safely record this and loop back
 384                                  * to cleanup the other buffers. Don't need to
 385                                  * remove the clustered uptodate information
 386                                  * for this bh as it's not marked locally
 387                                  * uptodate. */
 388                                 status = -EIO;
 389                                 clear_buffer_needs_validate(bh);
 390                                 goto read_failure;
 391                         }
 392
 393                         if (buffer_needs_validate(bh)) {
 394                                 /* We never set NeedsValidate if the
 395                                  * buffer was held by the journal, so
 396                                  * that better not have changed */
 397                                 BUG_ON(buffer_jbd(bh));
 398                                 clear_buffer_needs_validate(bh);
 399                                 status = validate(sb, bh);
 400                                 if (status)
 401                                         goto read_failure;
 402                         }
 403                 }
 404
 405                 /* Always set the buffer in the cache, even if it was
 406                  * a forced read, or read-ahead which hasn't yet
 407                  * completed. */
 408                 ocfs2_set_buffer_uptodate(ci, bh);
 409         }
 410         ocfs2_metadata_cache_io_unlock(ci);
 411
 412         trace_ocfs2_read_blocks_end((unsigned long long)block, nr,
 413                                     flags, ignore_cache);
 414
 415 bail:
 416
 417         return status;
 418 }
 419
 420 /* Check whether the blkno is the super block or one of the backups. */
 421 static void ocfs2_check_super_or_backup(struct super_block *sb,
 422                                         sector_t blkno)
 423 {
 424         int i;
 425         u64 backup_blkno;
 426
 427         if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
 428                 return;
 429
 430         for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
 431                 backup_blkno = ocfs2_backup_super_blkno(sb, i);
 432                 if (backup_blkno == blkno)
 433                         return;
 434         }
 435
 436         BUG();
 437 }
 438
 439 /*
 440  * Write super block and backups doesn't need to collaborate with journal,
 441  * so we don't need to lock ip_io_mutex and ci doesn't need to bea passed
 442  * into this function.
 443  */
 444 int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
 445                                 struct buffer_head *bh)
 446 {
 447         int ret = 0;
 448         struct ocfs2_dinode *di = (struct ocfs2_dinode *)bh->b_data;
 449
 450         BUG_ON(buffer_jbd(bh));
 451         ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
 452
 453         if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
 454                 ret = -EROFS;
 455                 mlog_errno(ret);
 456                 goto out;
 457         }
 458
 459         lock_buffer(bh);
 460         set_buffer_uptodate(bh);
 461
 462         /* remove from dirty list before I/O. */
 463         clear_buffer_dirty(bh);
 464
 465         get_bh(bh); /* for end_buffer_write_sync() */
 466         bh->b_end_io = end_buffer_write_sync;
 467         ocfs2_compute_meta_ecc(osb->sb, bh->b_data, &di->i_check);
 468         submit_bh(REQ_OP_WRITE, 0, bh);
 469
 470         wait_on_buffer(bh);
 471
 472         if (!buffer_uptodate(bh)) {
 473                 ret = -EIO;
 474                 mlog_errno(ret);
 475         }
 476
 477 out:
 478         return ret;
 479 }