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 ocfs2_super *osb, u64 block, int nr,
 174                       struct buffer_head *bhs[], int flags,
 175                       struct inode *inode)
 176 {
 177         int status = 0;
 178         struct super_block *sb;
 179         int i, ignore_cache = 0;
 180         struct buffer_head *bh;
 181
 182         mlog_entry("(block=(%llu), nr=(%d), flags=%d, inode=%p)\n",
 183                    (unsigned long long)block, nr, flags, inode);
 184
 185         BUG_ON((flags & OCFS2_BH_READAHEAD) &&
 186                (!inode || !(flags & OCFS2_BH_CACHED)));
 187
 188         if (osb == NULL || osb->sb == NULL || bhs == NULL) {
 189                 status = -EINVAL;
 190                 mlog_errno(status);
 191                 goto bail;
 192         }
 193
 194         if (nr < 0) {
 195                 mlog(ML_ERROR, "asked to read %d blocks!\n", nr);
 196                 status = -EINVAL;
 197                 mlog_errno(status);
 198                 goto bail;
 199         }
 200
 201         if (nr == 0) {
 202                 mlog(ML_BH_IO, "No buffers will be read!\n");
 203                 status = 0;
 204                 goto bail;
 205         }
 206
 207         sb = osb->sb;
 208
 209         if (flags & OCFS2_BH_CACHED && !inode)
 210                 flags &= ~OCFS2_BH_CACHED;
 211
 212         if (inode)
 213                 mutex_lock(&OCFS2_I(inode)->ip_io_mutex);
 214         for (i = 0 ; i < nr ; i++) {
 215                 if (bhs[i] == NULL) {
 216                         bhs[i] = sb_getblk(sb, block++);
 217                         if (bhs[i] == NULL) {
 218                                 if (inode)
 219                                         mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
 220                                 status = -EIO;
 221                                 mlog_errno(status);
 222                                 goto bail;
 223                         }
 224                 }
 225                 bh = bhs[i];
 226                 ignore_cache = 0;
 227
 228                 /* There are three read-ahead cases here which we need to
 229                  * be concerned with. All three assume a buffer has
 230                  * previously been submitted with OCFS2_BH_READAHEAD
 231                  * and it hasn't yet completed I/O.
 232                  *
 233                  * 1) The current request is sync to disk. This rarely
 234                  *    happens these days, and never when performance
 235                  *    matters - the code can just wait on the buffer
 236                  *    lock and re-submit.
 237                  *
 238                  * 2) The current request is cached, but not
 239                  *    readahead. ocfs2_buffer_uptodate() will return
 240                  *    false anyway, so we'll wind up waiting on the
 241                  *    buffer lock to do I/O. We re-check the request
 242                  *    with after getting the lock to avoid a re-submit.
 243                  *
 244                  * 3) The current request is readahead (and so must
 245                  *    also be a caching one). We short circuit if the
 246                  *    buffer is locked (under I/O) and if it's in the
 247                  *    uptodate cache. The re-check from #2 catches the
 248                  *    case that the previous read-ahead completes just
 249                  *    before our is-it-in-flight check.
 250                  */
 251
 252                 if (flags & OCFS2_BH_CACHED &&
 253                     !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                         ignore_cache = 1;
 259                 }
 260
 261                 /* XXX: Can we ever get this and *not* have the cached
 262                  * flag set? */
 263                 if (buffer_jbd(bh)) {
 264                         if (!(flags & OCFS2_BH_CACHED) || 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 (!(flags & OCFS2_BH_CACHED) || 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_CACHED)
 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                         bh->b_end_io = end_buffer_read_sync;
 316                         submit_bh(READ, bh);
 317                         continue;
 318                 }
 319         }
 320
 321         status = 0;
 322
 323         for (i = (nr - 1); i >= 0; i--) {
 324                 bh = bhs[i];
 325
 326                 if (!(flags & OCFS2_BH_READAHEAD)) {
 327                         /* We know this can't have changed as we hold the
 328                          * inode sem. Avoid doing any work on the bh if the
 329                          * journal has it. */
 330                         if (!buffer_jbd(bh))
 331                                 wait_on_buffer(bh);
 332
 333                         if (!buffer_uptodate(bh)) {
 334                                 /* Status won't be cleared from here on out,
 335                                  * so we can safely record this and loop back
 336                                  * to cleanup the other buffers. Don't need to
 337                                  * remove the clustered uptodate information
 338                                  * for this bh as it's not marked locally
 339                                  * uptodate. */
 340                                 status = -EIO;
 341                                 put_bh(bh);
 342                                 bhs[i] = NULL;
 343                                 continue;
 344                         }
 345                 }
 346
 347                 /* Always set the buffer in the cache, even if it was
 348                  * a forced read, or read-ahead which hasn't yet
 349                  * completed. */
 350                 if (inode)
 351                         ocfs2_set_buffer_uptodate(inode, bh);
 352         }
 353         if (inode)
 354                 mutex_unlock(&OCFS2_I(inode)->ip_io_mutex);
 355
 356         mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s, flags=0x%x\n",
 357              (unsigned long long)block, nr,
 358              (!(flags & OCFS2_BH_CACHED) || ignore_cache) ? "no" : "yes", flags);
 359
 360 bail:
 361
 362         mlog_exit(status);
 363         return status;
 364 }
 365
 366 /* Check whether the blkno is the super block or one of the backups. */
 367 static void ocfs2_check_super_or_backup(struct super_block *sb,
 368                                         sector_t blkno)
 369 {
 370         int i;
 371         u64 backup_blkno;
 372
 373         if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
 374                 return;
 375
 376         for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
 377                 backup_blkno = ocfs2_backup_super_blkno(sb, i);
 378                 if (backup_blkno == blkno)
 379                         return;
 380         }
 381
 382         BUG();
 383 }
 384
 385 /*
 386  * Write super block and backups doesn't need to collaborate with journal,
 387  * so we don't need to lock ip_io_mutex and inode doesn't need to bea passed
 388  * into this function.
 389  */
 390 int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
 391                                 struct buffer_head *bh)
 392 {
 393         int ret = 0;
 394
 395         mlog_entry_void();
 396
 397         BUG_ON(buffer_jbd(bh));
 398         ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
 399
 400         if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
 401                 ret = -EROFS;
 402                 goto out;
 403         }
 404
 405         lock_buffer(bh);
 406         set_buffer_uptodate(bh);
 407
 408         /* remove from dirty list before I/O. */
 409         clear_buffer_dirty(bh);
 410
 411         get_bh(bh); /* for end_buffer_write_sync() */
 412         bh->b_end_io = end_buffer_write_sync;
 413         submit_bh(WRITE, bh);
 414
 415         wait_on_buffer(bh);
 416
 417         if (!buffer_uptodate(bh)) {
 418                 ret = -EIO;
 419                 put_bh(bh);
 420         }
 421
 422 out:
 423         mlog_exit(ret);
 424         return ret;
 425 }