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_BH_IO, 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 /* No need to wait on the buffer if it's managed by JBD. */ 151 if (!buffer_jbd(bh)) 152 wait_on_buffer(bh); 153 154 if (!buffer_uptodate(bh)) { 155 /* Status won't be cleared from here on out, 156 * so we can safely record this and loop back 157 * to cleanup the other buffers. */ 158 status = -EIO; 159 put_bh(bh); 160 bhs[i - 1] = NULL; 161 } 162 } 163 164 bail: 165 return status; 166 } 167 168 int ocfs2_read_blocks(struct inode *inode, u64 block, int nr, 169 struct buffer_head *bhs[], int flags) 170 { 171 int status = 0; 172 int i, ignore_cache = 0; 173 struct buffer_head *bh; 174 175 mlog_entry("(inode=%p, block=(%llu), nr=(%d), flags=%d)\n", 176 inode, (unsigned long long)block, nr, flags); 177 178 BUG_ON(!inode); 179 BUG_ON((flags & OCFS2_BH_READAHEAD) && 180 (flags & OCFS2_BH_IGNORE_CACHE)); 181 182 if (bhs == NULL) { 183 status = -EINVAL; 184 mlog_errno(status); 185 goto bail; 186 } 187 188 if (nr < 0) { 189 mlog(ML_ERROR, "asked to read %d blocks!\n", nr); 190 status = -EINVAL; 191 mlog_errno(status); 192 goto bail; 193 } 194 195 if (nr == 0) { 196 mlog(ML_BH_IO, "No buffers will be read!\n"); 197 status = 0; 198 goto bail; 199 } 200 201 mutex_lock(&OCFS2_I(inode)->ip_io_mutex); 202 for (i = 0 ; i < nr ; i++) { 203 if (bhs[i] == NULL) { 204 bhs[i] = sb_getblk(inode->i_sb, block++); 205 if (bhs[i] == NULL) { 206 mutex_unlock(&OCFS2_I(inode)->ip_io_mutex); 207 status = -EIO; 208 mlog_errno(status); 209 goto bail; 210 } 211 } 212 bh = bhs[i]; 213 ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE); 214 215 /* There are three read-ahead cases here which we need to 216 * be concerned with. All three assume a buffer has 217 * previously been submitted with OCFS2_BH_READAHEAD 218 * and it hasn't yet completed I/O. 219 * 220 * 1) The current request is sync to disk. This rarely 221 * happens these days, and never when performance 222 * matters - the code can just wait on the buffer 223 * lock and re-submit. 224 * 225 * 2) The current request is cached, but not 226 * readahead. ocfs2_buffer_uptodate() will return 227 * false anyway, so we'll wind up waiting on the 228 * buffer lock to do I/O. We re-check the request 229 * with after getting the lock to avoid a re-submit. 230 * 231 * 3) The current request is readahead (and so must 232 * also be a caching one). We short circuit if the 233 * buffer is locked (under I/O) and if it's in the 234 * uptodate cache. The re-check from #2 catches the 235 * case that the previous read-ahead completes just 236 * before our is-it-in-flight check. 237 */ 238 239 if (!ignore_cache && !ocfs2_buffer_uptodate(inode, bh)) { 240 mlog(ML_UPTODATE, 241 "bh (%llu), inode %llu not uptodate\n", 242 (unsigned long long)bh->b_blocknr, 243 (unsigned long long)OCFS2_I(inode)->ip_blkno); 244 /* We're using ignore_cache here to say 245 * "go to disk" */ 246 ignore_cache = 1; 247 } 248 249 if (buffer_jbd(bh)) { 250 if (ignore_cache) 251 mlog(ML_BH_IO, "trying to sync read a jbd " 252 "managed bh (blocknr = %llu)\n", 253 (unsigned long long)bh->b_blocknr); 254 continue; 255 } 256 257 if (ignore_cache) { 258 if (buffer_dirty(bh)) { 259 /* This should probably be a BUG, or 260 * at least return an error. */ 261 mlog(ML_BH_IO, "asking me to sync read a dirty " 262 "buffer! (blocknr = %llu)\n", 263 (unsigned long long)bh->b_blocknr); 264 continue; 265 } 266 267 /* A read-ahead request was made - if the 268 * buffer is already under read-ahead from a 269 * previously submitted request than we are 270 * done here. */ 271 if ((flags & OCFS2_BH_READAHEAD) 272 && ocfs2_buffer_read_ahead(inode, bh)) 273 continue; 274 275 lock_buffer(bh); 276 if (buffer_jbd(bh)) { 277 #ifdef CATCH_BH_JBD_RACES 278 mlog(ML_ERROR, "block %llu had the JBD bit set " 279 "while I was in lock_buffer!", 280 (unsigned long long)bh->b_blocknr); 281 BUG(); 282 #else 283 unlock_buffer(bh); 284 continue; 285 #endif 286 } 287 288 /* Re-check ocfs2_buffer_uptodate() as a 289 * previously read-ahead buffer may have 290 * completed I/O while we were waiting for the 291 * buffer lock. */ 292 if (!(flags & OCFS2_BH_IGNORE_CACHE) 293 && !(flags & OCFS2_BH_READAHEAD) 294 && ocfs2_buffer_uptodate(inode, bh)) { 295 unlock_buffer(bh); 296 continue; 297 } 298 299 clear_buffer_uptodate(bh); 300 get_bh(bh); /* for end_buffer_read_sync() */ 301 bh->b_end_io = end_buffer_read_sync; 302 submit_bh(READ, bh); 303 continue; 304 } 305 } 306 307 status = 0; 308 309 for (i = (nr - 1); i >= 0; i--) { 310 bh = bhs[i]; 311 312 if (!(flags & OCFS2_BH_READAHEAD)) { 313 /* We know this can't have changed as we hold the 314 * inode sem. Avoid doing any work on the bh if the 315 * journal has it. */ 316 if (!buffer_jbd(bh)) 317 wait_on_buffer(bh); 318 319 if (!buffer_uptodate(bh)) { 320 /* Status won't be cleared from here on out, 321 * so we can safely record this and loop back 322 * to cleanup the other buffers. Don't need to 323 * remove the clustered uptodate information 324 * for this bh as it's not marked locally 325 * uptodate. */ 326 status = -EIO; 327 put_bh(bh); 328 bhs[i] = NULL; 329 continue; 330 } 331 } 332 333 /* Always set the buffer in the cache, even if it was 334 * a forced read, or read-ahead which hasn't yet 335 * completed. */ 336 ocfs2_set_buffer_uptodate(inode, bh); 337 } 338 mutex_unlock(&OCFS2_I(inode)->ip_io_mutex); 339 340 mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s, flags=0x%x\n", 341 (unsigned long long)block, nr, 342 ((flags & OCFS2_BH_IGNORE_CACHE) || ignore_cache) ? "no" : "yes", 343 flags); 344 345 bail: 346 347 mlog_exit(status); 348 return status; 349 } 350 351 /* Check whether the blkno is the super block or one of the backups. */ 352 static void ocfs2_check_super_or_backup(struct super_block *sb, 353 sector_t blkno) 354 { 355 int i; 356 u64 backup_blkno; 357 358 if (blkno == OCFS2_SUPER_BLOCK_BLKNO) 359 return; 360 361 for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) { 362 backup_blkno = ocfs2_backup_super_blkno(sb, i); 363 if (backup_blkno == blkno) 364 return; 365 } 366 367 BUG(); 368 } 369 370 /* 371 * Write super block and backups doesn't need to collaborate with journal, 372 * so we don't need to lock ip_io_mutex and inode doesn't need to bea passed 373 * into this function. 374 */ 375 int ocfs2_write_super_or_backup(struct ocfs2_super *osb, 376 struct buffer_head *bh) 377 { 378 int ret = 0; 379 380 mlog_entry_void(); 381 382 BUG_ON(buffer_jbd(bh)); 383 ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr); 384 385 if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) { 386 ret = -EROFS; 387 goto out; 388 } 389 390 lock_buffer(bh); 391 set_buffer_uptodate(bh); 392 393 /* remove from dirty list before I/O. */ 394 clear_buffer_dirty(bh); 395 396 get_bh(bh); /* for end_buffer_write_sync() */ 397 bh->b_end_io = end_buffer_write_sync; 398 submit_bh(WRITE, bh); 399 400 wait_on_buffer(bh); 401 402 if (!buffer_uptodate(bh)) { 403 ret = -EIO; 404 put_bh(bh); 405 } 406 407 out: 408 mlog_exit(ret); 409 return ret; 410 } 411