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 int ocfs2_write_block(struct ocfs2_super *osb, struct buffer_head *bh,
  43                       struct inode *inode)
  44 {
  45         int ret = 0;
  46
  47         mlog_entry("(bh->b_blocknr = %llu, inode=%p)\n",
  48                    (unsigned long long)bh->b_blocknr, inode);
  49
  50         BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO);
  51         BUG_ON(buffer_jbd(bh));
  52
  53         /* No need to check for a soft readonly file system here. non
  54          * journalled writes are only ever done on system files which
  55          * can get modified during recovery even if read-only. */
  56         if (ocfs2_is_hard_readonly(osb)) {
  57                 ret = -EROFS;
  58                 goto out;
  59         }
  60
  61         mutex_lock(&OCFS2_I(inode)->ip_io_mutex);
  62
  63         lock_buffer(bh);
  64         set_buffer_uptodate(bh);
  65
  66         /* remove from dirty list before I/O. */
  67         clear_buffer_dirty(bh);
  68
  69         get_bh(bh); /* for end_buffer_write_sync() */
  70         bh->b_end_io = end_buffer_write_sync;
  71         submit_bh(WRITE, bh);
  72
  73         wait_on_buffer(bh);
  74
  75         if (buffer_uptodate(bh)) {
  76                 ocfs2_set_buffer_uptodate(inode, bh);
  77         } else {
  78                 /* We don't need to remove the clustered uptodate
  79                  * information for this bh as it's not marked locally
  80                  * uptodate. */
  81                 ret = -EIO;
  82                 put_bh(bh);
  83         }
  84
  85         mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
  86 out:
  87         mlog_exit(ret);
  88         return ret;
  89 }
  90
  91 int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block,
  92                            unsigned int nr, struct buffer_head *bhs[])
  93 {
  94         int status = 0;
  95         unsigned int i;
  96         struct buffer_head *bh;
  97
  98         if (!nr) {
  99                 mlog(ML_BH_IO, "No buffers will be read!\n");
 100                 goto bail;
 101         }
 102
 103         for (i = 0 ; i < nr ; i++) {
 104                 if (bhs[i] == NULL) {
 105                         bhs[i] = sb_getblk(osb->sb, block++);
 106                         if (bhs[i] == NULL) {
 107                                 status = -EIO;
 108                                 mlog_errno(status);
 109                                 goto bail;
 110                         }
 111                 }
 112                 bh = bhs[i];
 113
 114                 if (buffer_jbd(bh)) {
 115                         mlog(ML_ERROR,
 116                              "trying to sync read a jbd "
 117                              "managed bh (blocknr = %llu), skipping\n",
 118                              (unsigned long long)bh->b_blocknr);
 119                         continue;
 120                 }
 121
 122                 if (buffer_dirty(bh)) {
 123                         /* This should probably be a BUG, or
 124                          * at least return an error. */
 125                         mlog(ML_ERROR,
 126                              "trying to sync read a dirty "
 127                              "buffer! (blocknr = %llu), skipping\n",
 128                              (unsigned long long)bh->b_blocknr);
 129                         continue;
 130                 }
 131
 132                 lock_buffer(bh);
 133                 if (buffer_jbd(bh)) {
 134                         mlog(ML_ERROR,
 135                              "block %llu had the JBD bit set "
 136                              "while I was in lock_buffer!",
 137                              (unsigned long long)bh->b_blocknr);
 138                         BUG();
 139                 }
 140
 141                 clear_buffer_uptodate(bh);
 142                 get_bh(bh); /* for end_buffer_read_sync() */
 143                 bh->b_end_io = end_buffer_read_sync;
 144                 submit_bh(READ, bh);
 145         }
 146
 147         for (i = nr; i > 0; i--) {
 148                 bh = bhs[i - 1];
 149
 150                 if (buffer_jbd(bh)) {
 151                         mlog(ML_ERROR,
 152                              "the journal got the buffer while it was "
 153                              "locked for io! (blocknr = %llu)\n",
 154                              (unsigned long long)bh->b_blocknr);
 155                         BUG();
 156                 }
 157
 158                 wait_on_buffer(bh);
 159                 if (!buffer_uptodate(bh)) {
 160                         /* Status won't be cleared from here on out,
 161                          * so we can safely record this and loop back
 162                          * to cleanup the other buffers. */
 163                         status = -EIO;
 164                         put_bh(bh);
 165                         bhs[i - 1] = NULL;
 166                 }
 167         }
 168
 169 bail:
 170         return status;
 171 }
 172
 173 int ocfs2_read_blocks(struct inode *inode, u64 block, int nr,
 174                       struct buffer_head *bhs[], int flags)
 175 {
 176         int status = 0;
 177         int i, ignore_cache = 0;
 178         struct buffer_head *bh;
 179
 180         mlog_entry("(inode=%p, block=(%llu), nr=(%d), flags=%d)\n",
 181                    inode, (unsigned long long)block, nr, flags);
 182
 183         BUG_ON(!inode);
 184         BUG_ON((flags & OCFS2_BH_READAHEAD) &&
 185                (flags & OCFS2_BH_IGNORE_CACHE));
 186
 187         if (bhs == NULL) {
 188                 status = -EINVAL;
 189                 mlog_errno(status);
 190                 goto bail;
 191         }
 192
 193         if (nr < 0) {
 194                 mlog(ML_ERROR, "asked to read %d blocks!\n", nr);
 195                 status = -EINVAL;
 196                 mlog_errno(status);
 197                 goto bail;
 198         }
 199
 200         if (nr == 0) {
 201                 mlog(ML_BH_IO, "No buffers will be read!\n");
 202                 status = 0;
 203                 goto bail;
 204         }
 205
 206         mutex_lock(&OCFS2_I(inode)->ip_io_mutex);
 207         for (i = 0 ; i < nr ; i++) {
 208                 if (bhs[i] == NULL) {
 209                         bhs[i] = sb_getblk(inode->i_sb, block++);
 210                         if (bhs[i] == NULL) {
 211                                 mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
 212                                 status = -EIO;
 213                                 mlog_errno(status);
 214                                 goto bail;
 215                         }
 216                 }
 217                 bh = bhs[i];
 218                 ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE);
 219
 220                 /* There are three read-ahead cases here which we need to
 221                  * be concerned with. All three assume a buffer has
 222                  * previously been submitted with OCFS2_BH_READAHEAD
 223                  * and it hasn't yet completed I/O.
 224                  *
 225                  * 1) The current request is sync to disk. This rarely
 226                  *    happens these days, and never when performance
 227                  *    matters - the code can just wait on the buffer
 228                  *    lock and re-submit.
 229                  *
 230                  * 2) The current request is cached, but not
 231                  *    readahead. ocfs2_buffer_uptodate() will return
 232                  *    false anyway, so we'll wind up waiting on the
 233                  *    buffer lock to do I/O. We re-check the request
 234                  *    with after getting the lock to avoid a re-submit.
 235                  *
 236                  * 3) The current request is readahead (and so must
 237                  *    also be a caching one). We short circuit if the
 238                  *    buffer is locked (under I/O) and if it's in the
 239                  *    uptodate cache. The re-check from #2 catches the
 240                  *    case that the previous read-ahead completes just
 241                  *    before our is-it-in-flight check.
 242                  */
 243
 244                 if (!ignore_cache && !ocfs2_buffer_uptodate(inode, bh)) {
 245                         mlog(ML_UPTODATE,
 246                              "bh (%llu), inode %llu not uptodate\n",
 247                              (unsigned long long)bh->b_blocknr,
 248                              (unsigned long long)OCFS2_I(inode)->ip_blkno);
 249                         /* We're using ignore_cache here to say
 250                          * "go to disk" */
 251                         ignore_cache = 1;
 252                 }
 253
 254                 /* XXX: Can we ever get this and *not* have the cached
 255                  * flag set? */
 256                 if (buffer_jbd(bh)) {
 257                         if (ignore_cache)
 258                                 mlog(ML_BH_IO, "trying to sync read a jbd "
 259                                                "managed bh (blocknr = %llu)\n",
 260                                      (unsigned long long)bh->b_blocknr);
 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                                 mlog(ML_BH_IO, "asking me to sync read a dirty "
 269                                                "buffer! (blocknr = %llu)\n",
 270                                      (unsigned long long)bh->b_blocknr);
 271                                 continue;
 272                         }
 273
 274                         /* A read-ahead request was made - if the
 275                          * buffer is already under read-ahead from a
 276                          * previously submitted request than we are
 277                          * done here. */
 278                         if ((flags & OCFS2_BH_READAHEAD)
 279                             && ocfs2_buffer_read_ahead(inode, bh))
 280                                 continue;
 281
 282                         lock_buffer(bh);
 283                         if (buffer_jbd(bh)) {
 284 #ifdef CATCH_BH_JBD_RACES
 285                                 mlog(ML_ERROR, "block %llu had the JBD bit set "
 286                                                "while I was in lock_buffer!",
 287                                      (unsigned long long)bh->b_blocknr);
 288                                 BUG();
 289 #else
 290                                 unlock_buffer(bh);
 291                                 continue;
 292 #endif
 293                         }
 294
 295                         /* Re-check ocfs2_buffer_uptodate() as a
 296                          * previously read-ahead buffer may have
 297                          * completed I/O while we were waiting for the
 298                          * buffer lock. */
 299                         if (!(flags & OCFS2_BH_IGNORE_CACHE)
 300                             && !(flags & OCFS2_BH_READAHEAD)
 301                             && ocfs2_buffer_uptodate(inode, bh)) {
 302                                 unlock_buffer(bh);
 303                                 continue;
 304                         }
 305
 306                         clear_buffer_uptodate(bh);
 307                         get_bh(bh); /* for end_buffer_read_sync() */
 308                         bh->b_end_io = end_buffer_read_sync;
 309                         submit_bh(READ, bh);
 310                         continue;
 311                 }
 312         }
 313
 314         status = 0;
 315
 316         for (i = (nr - 1); i >= 0; i--) {
 317                 bh = bhs[i];
 318
 319                 if (!(flags & OCFS2_BH_READAHEAD)) {
 320                         /* We know this can't have changed as we hold the
 321                          * inode sem. Avoid doing any work on the bh if the
 322                          * journal has it. */
 323                         if (!buffer_jbd(bh))
 324                                 wait_on_buffer(bh);
 325
 326                         if (!buffer_uptodate(bh)) {
 327                                 /* Status won't be cleared from here on out,
 328                                  * so we can safely record this and loop back
 329                                  * to cleanup the other buffers. Don't need to
 330                                  * remove the clustered uptodate information
 331                                  * for this bh as it's not marked locally
 332                                  * uptodate. */
 333                                 status = -EIO;
 334                                 put_bh(bh);
 335                                 bhs[i] = NULL;
 336                                 continue;
 337                         }
 338                 }
 339
 340                 /* Always set the buffer in the cache, even if it was
 341                  * a forced read, or read-ahead which hasn't yet
 342                  * completed. */
 343                 ocfs2_set_buffer_uptodate(inode, bh);
 344         }
 345         mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
 346
 347         mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s, flags=0x%x\n",
 348              (unsigned long long)block, nr,
 349              ((flags & OCFS2_BH_IGNORE_CACHE) || ignore_cache) ? "no" : "yes",
 350              flags);
 351
 352 bail:
 353
 354         mlog_exit(status);
 355         return status;
 356 }
 357
 358 /* Check whether the blkno is the super block or one of the backups. */
 359 static void ocfs2_check_super_or_backup(struct super_block *sb,
 360                                         sector_t blkno)
 361 {
 362         int i;
 363         u64 backup_blkno;
 364
 365         if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
 366                 return;
 367
 368         for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
 369                 backup_blkno = ocfs2_backup_super_blkno(sb, i);
 370                 if (backup_blkno == blkno)
 371                         return;
 372         }
 373
 374         BUG();
 375 }
 376
 377 /*
 378  * Write super block and backups doesn't need to collaborate with journal,
 379  * so we don't need to lock ip_io_mutex and inode doesn't need to bea passed
 380  * into this function.
 381  */
 382 int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
 383                                 struct buffer_head *bh)
 384 {
 385         int ret = 0;
 386
 387         mlog_entry_void();
 388
 389         BUG_ON(buffer_jbd(bh));
 390         ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
 391
 392         if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
 393                 ret = -EROFS;
 394                 goto out;
 395         }
 396
 397         lock_buffer(bh);
 398         set_buffer_uptodate(bh);
 399
 400         /* remove from dirty list before I/O. */
 401         clear_buffer_dirty(bh);
 402
 403         get_bh(bh); /* for end_buffer_write_sync() */
 404         bh->b_end_io = end_buffer_write_sync;
 405         submit_bh(WRITE, bh);
 406
 407         wait_on_buffer(bh);
 408
 409         if (!buffer_uptodate(bh)) {
 410                 ret = -EIO;
 411                 put_bh(bh);
 412         }
 413
 414 out:
 415         mlog_exit(ret);
 416         return ret;
 417 }