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 } 418