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 /* 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 mlog_entry("(bh->b_blocknr = %llu, ci=%p)\n", 60 (unsigned long long)bh->b_blocknr, ci); 61 62 BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO); 63 BUG_ON(buffer_jbd(bh)); 64 65 /* No need to check for a soft readonly file system here. non 66 * journalled writes are only ever done on system files which 67 * can get modified during recovery even if read-only. */ 68 if (ocfs2_is_hard_readonly(osb)) { 69 ret = -EROFS; 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(WRITE, 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 put_bh(bh); 95 } 96 97 ocfs2_metadata_cache_io_unlock(ci); 98 out: 99 mlog_exit(ret); 100 return ret; 101 } 102 103 int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block, 104 unsigned int nr, struct buffer_head *bhs[]) 105 { 106 int status = 0; 107 unsigned int i; 108 struct buffer_head *bh; 109 110 if (!nr) { 111 mlog(ML_BH_IO, "No buffers will be read!\n"); 112 goto bail; 113 } 114 115 for (i = 0 ; i < nr ; i++) { 116 if (bhs[i] == NULL) { 117 bhs[i] = sb_getblk(osb->sb, block++); 118 if (bhs[i] == NULL) { 119 status = -EIO; 120 mlog_errno(status); 121 goto bail; 122 } 123 } 124 bh = bhs[i]; 125 126 if (buffer_jbd(bh)) { 127 mlog(ML_BH_IO, 128 "trying to sync read a jbd " 129 "managed bh (blocknr = %llu), skipping\n", 130 (unsigned long long)bh->b_blocknr); 131 continue; 132 } 133 134 if (buffer_dirty(bh)) { 135 /* This should probably be a BUG, or 136 * at least return an error. */ 137 mlog(ML_ERROR, 138 "trying to sync read a dirty " 139 "buffer! (blocknr = %llu), skipping\n", 140 (unsigned long long)bh->b_blocknr); 141 continue; 142 } 143 144 lock_buffer(bh); 145 if (buffer_jbd(bh)) { 146 mlog(ML_ERROR, 147 "block %llu had the JBD bit set " 148 "while I was in lock_buffer!", 149 (unsigned long long)bh->b_blocknr); 150 BUG(); 151 } 152 153 clear_buffer_uptodate(bh); 154 get_bh(bh); /* for end_buffer_read_sync() */ 155 bh->b_end_io = end_buffer_read_sync; 156 submit_bh(READ, bh); 157 } 158 159 for (i = nr; i > 0; i--) { 160 bh = bhs[i - 1]; 161 162 /* No need to wait on the buffer if it's managed by JBD. */ 163 if (!buffer_jbd(bh)) 164 wait_on_buffer(bh); 165 166 if (!buffer_uptodate(bh)) { 167 /* Status won't be cleared from here on out, 168 * so we can safely record this and loop back 169 * to cleanup the other buffers. */ 170 status = -EIO; 171 put_bh(bh); 172 bhs[i - 1] = NULL; 173 } 174 } 175 176 bail: 177 return status; 178 } 179 180 int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr, 181 struct buffer_head *bhs[], int flags, 182 int (*validate)(struct super_block *sb, 183 struct buffer_head *bh)) 184 { 185 int status = 0; 186 int i, ignore_cache = 0; 187 struct buffer_head *bh; 188 struct super_block *sb = ocfs2_metadata_cache_get_super(ci); 189 190 mlog_entry("(ci=%p, block=(%llu), nr=(%d), flags=%d)\n", 191 ci, (unsigned long long)block, nr, flags); 192 193 BUG_ON(!ci); 194 BUG_ON((flags & OCFS2_BH_READAHEAD) && 195 (flags & OCFS2_BH_IGNORE_CACHE)); 196 197 if (bhs == NULL) { 198 status = -EINVAL; 199 mlog_errno(status); 200 goto bail; 201 } 202 203 if (nr < 0) { 204 mlog(ML_ERROR, "asked to read %d blocks!\n", nr); 205 status = -EINVAL; 206 mlog_errno(status); 207 goto bail; 208 } 209 210 if (nr == 0) { 211 mlog(ML_BH_IO, "No buffers will be read!\n"); 212 status = 0; 213 goto bail; 214 } 215 216 ocfs2_metadata_cache_io_lock(ci); 217 for (i = 0 ; i < nr ; i++) { 218 if (bhs[i] == NULL) { 219 bhs[i] = sb_getblk(sb, block++); 220 if (bhs[i] == NULL) { 221 ocfs2_metadata_cache_io_unlock(ci); 222 status = -EIO; 223 mlog_errno(status); 224 goto bail; 225 } 226 } 227 bh = bhs[i]; 228 ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE); 229 230 /* There are three read-ahead cases here which we need to 231 * be concerned with. All three assume a buffer has 232 * previously been submitted with OCFS2_BH_READAHEAD 233 * and it hasn't yet completed I/O. 234 * 235 * 1) The current request is sync to disk. This rarely 236 * happens these days, and never when performance 237 * matters - the code can just wait on the buffer 238 * lock and re-submit. 239 * 240 * 2) The current request is cached, but not 241 * readahead. ocfs2_buffer_uptodate() will return 242 * false anyway, so we'll wind up waiting on the 243 * buffer lock to do I/O. We re-check the request 244 * with after getting the lock to avoid a re-submit. 245 * 246 * 3) The current request is readahead (and so must 247 * also be a caching one). We short circuit if the 248 * buffer is locked (under I/O) and if it's in the 249 * uptodate cache. The re-check from #2 catches the 250 * case that the previous read-ahead completes just 251 * before our is-it-in-flight check. 252 */ 253 254 if (!ignore_cache && !ocfs2_buffer_uptodate(ci, bh)) { 255 mlog(ML_UPTODATE, 256 "bh (%llu), owner %llu not uptodate\n", 257 (unsigned long long)bh->b_blocknr, 258 (unsigned long long)ocfs2_metadata_cache_owner(ci)); 259 /* We're using ignore_cache here to say 260 * "go to disk" */ 261 ignore_cache = 1; 262 } 263 264 if (buffer_jbd(bh)) { 265 if (ignore_cache) 266 mlog(ML_BH_IO, "trying to sync read a jbd " 267 "managed bh (blocknr = %llu)\n", 268 (unsigned long long)bh->b_blocknr); 269 continue; 270 } 271 272 if (ignore_cache) { 273 if (buffer_dirty(bh)) { 274 /* This should probably be a BUG, or 275 * at least return an error. */ 276 mlog(ML_BH_IO, "asking me to sync read a dirty " 277 "buffer! (blocknr = %llu)\n", 278 (unsigned long long)bh->b_blocknr); 279 continue; 280 } 281 282 /* A read-ahead request was made - if the 283 * buffer is already under read-ahead from a 284 * previously submitted request than we are 285 * done here. */ 286 if ((flags & OCFS2_BH_READAHEAD) 287 && ocfs2_buffer_read_ahead(ci, bh)) 288 continue; 289 290 lock_buffer(bh); 291 if (buffer_jbd(bh)) { 292 #ifdef CATCH_BH_JBD_RACES 293 mlog(ML_ERROR, "block %llu had the JBD bit set " 294 "while I was in lock_buffer!", 295 (unsigned long long)bh->b_blocknr); 296 BUG(); 297 #else 298 unlock_buffer(bh); 299 continue; 300 #endif 301 } 302 303 /* Re-check ocfs2_buffer_uptodate() as a 304 * previously read-ahead buffer may have 305 * completed I/O while we were waiting for the 306 * buffer lock. */ 307 if (!(flags & OCFS2_BH_IGNORE_CACHE) 308 && !(flags & OCFS2_BH_READAHEAD) 309 && ocfs2_buffer_uptodate(ci, bh)) { 310 unlock_buffer(bh); 311 continue; 312 } 313 314 clear_buffer_uptodate(bh); 315 get_bh(bh); /* for end_buffer_read_sync() */ 316 if (validate) 317 set_buffer_needs_validate(bh); 318 bh->b_end_io = end_buffer_read_sync; 319 submit_bh(READ, bh); 320 continue; 321 } 322 } 323 324 status = 0; 325 326 for (i = (nr - 1); i >= 0; i--) { 327 bh = bhs[i]; 328 329 if (!(flags & OCFS2_BH_READAHEAD)) { 330 /* We know this can't have changed as we hold the 331 * owner sem. Avoid doing any work on the bh if the 332 * journal has it. */ 333 if (!buffer_jbd(bh)) 334 wait_on_buffer(bh); 335 336 if (!buffer_uptodate(bh)) { 337 /* Status won't be cleared from here on out, 338 * so we can safely record this and loop back 339 * to cleanup the other buffers. Don't need to 340 * remove the clustered uptodate information 341 * for this bh as it's not marked locally 342 * uptodate. */ 343 status = -EIO; 344 put_bh(bh); 345 bhs[i] = NULL; 346 continue; 347 } 348 349 if (buffer_needs_validate(bh)) { 350 /* We never set NeedsValidate if the 351 * buffer was held by the journal, so 352 * that better not have changed */ 353 BUG_ON(buffer_jbd(bh)); 354 clear_buffer_needs_validate(bh); 355 status = validate(sb, bh); 356 if (status) { 357 put_bh(bh); 358 bhs[i] = NULL; 359 continue; 360 } 361 } 362 } 363 364 /* Always set the buffer in the cache, even if it was 365 * a forced read, or read-ahead which hasn't yet 366 * completed. */ 367 ocfs2_set_buffer_uptodate(ci, bh); 368 } 369 ocfs2_metadata_cache_io_unlock(ci); 370 371 mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s, flags=0x%x\n", 372 (unsigned long long)block, nr, 373 ((flags & OCFS2_BH_IGNORE_CACHE) || ignore_cache) ? "no" : "yes", 374 flags); 375 376 bail: 377 378 mlog_exit(status); 379 return status; 380 } 381 382 /* Check whether the blkno is the super block or one of the backups. */ 383 static void ocfs2_check_super_or_backup(struct super_block *sb, 384 sector_t blkno) 385 { 386 int i; 387 u64 backup_blkno; 388 389 if (blkno == OCFS2_SUPER_BLOCK_BLKNO) 390 return; 391 392 for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) { 393 backup_blkno = ocfs2_backup_super_blkno(sb, i); 394 if (backup_blkno == blkno) 395 return; 396 } 397 398 BUG(); 399 } 400 401 /* 402 * Write super block and backups doesn't need to collaborate with journal, 403 * so we don't need to lock ip_io_mutex and ci doesn't need to bea passed 404 * into this function. 405 */ 406 int ocfs2_write_super_or_backup(struct ocfs2_super *osb, 407 struct buffer_head *bh) 408 { 409 int ret = 0; 410 411 mlog_entry_void(); 412 413 BUG_ON(buffer_jbd(bh)); 414 ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr); 415 416 if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) { 417 ret = -EROFS; 418 goto out; 419 } 420 421 lock_buffer(bh); 422 set_buffer_uptodate(bh); 423 424 /* remove from dirty list before I/O. */ 425 clear_buffer_dirty(bh); 426 427 get_bh(bh); /* for end_buffer_write_sync() */ 428 bh->b_end_io = end_buffer_write_sync; 429 submit_bh(WRITE, bh); 430 431 wait_on_buffer(bh); 432 433 if (!buffer_uptodate(bh)) { 434 ret = -EIO; 435 put_bh(bh); 436 } 437 438 out: 439 mlog_exit(ret); 440 return ret; 441 } 442