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/highmem.h> 29 30 #include <cluster/masklog.h> 31 32 #include "ocfs2.h" 33 34 #include "alloc.h" 35 #include "inode.h" 36 #include "journal.h" 37 #include "uptodate.h" 38 #include "buffer_head_io.h" 39 #include "ocfs2_trace.h" 40 41 /* 42 * Bits on bh->b_state used by ocfs2. 43 * 44 * These MUST be after the JBD2 bits. Hence, we use BH_JBDPrivateStart. 45 */ 46 enum ocfs2_state_bits { 47 BH_NeedsValidate = BH_JBDPrivateStart, 48 }; 49 50 /* Expand the magic b_state functions */ 51 BUFFER_FNS(NeedsValidate, needs_validate); 52 53 int ocfs2_write_block(struct ocfs2_super *osb, struct buffer_head *bh, 54 struct ocfs2_caching_info *ci) 55 { 56 int ret = 0; 57 58 trace_ocfs2_write_block((unsigned long long)bh->b_blocknr, ci); 59 60 BUG_ON(bh->b_blocknr < OCFS2_SUPER_BLOCK_BLKNO); 61 BUG_ON(buffer_jbd(bh)); 62 63 /* No need to check for a soft readonly file system here. non 64 * journalled writes are only ever done on system files which 65 * can get modified during recovery even if read-only. */ 66 if (ocfs2_is_hard_readonly(osb)) { 67 ret = -EROFS; 68 mlog_errno(ret); 69 goto out; 70 } 71 72 ocfs2_metadata_cache_io_lock(ci); 73 74 lock_buffer(bh); 75 set_buffer_uptodate(bh); 76 77 /* remove from dirty list before I/O. */ 78 clear_buffer_dirty(bh); 79 80 get_bh(bh); /* for end_buffer_write_sync() */ 81 bh->b_end_io = end_buffer_write_sync; 82 submit_bh(WRITE, bh); 83 84 wait_on_buffer(bh); 85 86 if (buffer_uptodate(bh)) { 87 ocfs2_set_buffer_uptodate(ci, bh); 88 } else { 89 /* We don't need to remove the clustered uptodate 90 * information for this bh as it's not marked locally 91 * uptodate. */ 92 ret = -EIO; 93 mlog_errno(ret); 94 } 95 96 ocfs2_metadata_cache_io_unlock(ci); 97 out: 98 return ret; 99 } 100 101 int ocfs2_read_blocks_sync(struct ocfs2_super *osb, u64 block, 102 unsigned int nr, struct buffer_head *bhs[]) 103 { 104 int status = 0; 105 unsigned int i; 106 struct buffer_head *bh; 107 108 trace_ocfs2_read_blocks_sync((unsigned long long)block, nr); 109 110 if (!nr) 111 goto bail; 112 113 for (i = 0 ; i < nr ; i++) { 114 if (bhs[i] == NULL) { 115 bhs[i] = sb_getblk(osb->sb, block++); 116 if (bhs[i] == NULL) { 117 status = -ENOMEM; 118 mlog_errno(status); 119 goto bail; 120 } 121 } 122 bh = bhs[i]; 123 124 if (buffer_jbd(bh)) { 125 trace_ocfs2_read_blocks_sync_jbd( 126 (unsigned long long)bh->b_blocknr); 127 continue; 128 } 129 130 if (buffer_dirty(bh)) { 131 /* This should probably be a BUG, or 132 * at least return an error. */ 133 mlog(ML_ERROR, 134 "trying to sync read a dirty " 135 "buffer! (blocknr = %llu), skipping\n", 136 (unsigned long long)bh->b_blocknr); 137 continue; 138 } 139 140 lock_buffer(bh); 141 if (buffer_jbd(bh)) { 142 #ifdef CATCH_BH_JBD_RACES 143 mlog(ML_ERROR, 144 "block %llu had the JBD bit set " 145 "while I was in lock_buffer!", 146 (unsigned long long)bh->b_blocknr); 147 BUG(); 148 #else 149 unlock_buffer(bh); 150 continue; 151 #endif 152 } 153 154 clear_buffer_uptodate(bh); 155 get_bh(bh); /* for end_buffer_read_sync() */ 156 bh->b_end_io = end_buffer_read_sync; 157 submit_bh(READ, bh); 158 } 159 160 for (i = nr; i > 0; i--) { 161 bh = bhs[i - 1]; 162 163 /* No need to wait on the buffer if it's managed by JBD. */ 164 if (!buffer_jbd(bh)) 165 wait_on_buffer(bh); 166 167 if (!buffer_uptodate(bh)) { 168 /* Status won't be cleared from here on out, 169 * so we can safely record this and loop back 170 * to cleanup the other buffers. */ 171 status = -EIO; 172 put_bh(bh); 173 bhs[i - 1] = NULL; 174 } 175 } 176 177 bail: 178 return status; 179 } 180 181 int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr, 182 struct buffer_head *bhs[], int flags, 183 int (*validate)(struct super_block *sb, 184 struct buffer_head *bh)) 185 { 186 int status = 0; 187 int i, ignore_cache = 0; 188 struct buffer_head *bh; 189 struct super_block *sb = ocfs2_metadata_cache_get_super(ci); 190 191 trace_ocfs2_read_blocks_begin(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 status = 0; 212 goto bail; 213 } 214 215 ocfs2_metadata_cache_io_lock(ci); 216 for (i = 0 ; i < nr ; i++) { 217 if (bhs[i] == NULL) { 218 bhs[i] = sb_getblk(sb, block++); 219 if (bhs[i] == NULL) { 220 ocfs2_metadata_cache_io_unlock(ci); 221 status = -ENOMEM; 222 mlog_errno(status); 223 goto bail; 224 } 225 } 226 bh = bhs[i]; 227 ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE); 228 229 /* There are three read-ahead cases here which we need to 230 * be concerned with. All three assume a buffer has 231 * previously been submitted with OCFS2_BH_READAHEAD 232 * and it hasn't yet completed I/O. 233 * 234 * 1) The current request is sync to disk. This rarely 235 * happens these days, and never when performance 236 * matters - the code can just wait on the buffer 237 * lock and re-submit. 238 * 239 * 2) The current request is cached, but not 240 * readahead. ocfs2_buffer_uptodate() will return 241 * false anyway, so we'll wind up waiting on the 242 * buffer lock to do I/O. We re-check the request 243 * with after getting the lock to avoid a re-submit. 244 * 245 * 3) The current request is readahead (and so must 246 * also be a caching one). We short circuit if the 247 * buffer is locked (under I/O) and if it's in the 248 * uptodate cache. The re-check from #2 catches the 249 * case that the previous read-ahead completes just 250 * before our is-it-in-flight check. 251 */ 252 253 if (!ignore_cache && !ocfs2_buffer_uptodate(ci, bh)) { 254 trace_ocfs2_read_blocks_from_disk( 255 (unsigned long long)bh->b_blocknr, 256 (unsigned long long)ocfs2_metadata_cache_owner(ci)); 257 /* We're using ignore_cache here to say 258 * "go to disk" */ 259 ignore_cache = 1; 260 } 261 262 trace_ocfs2_read_blocks_bh((unsigned long long)bh->b_blocknr, 263 ignore_cache, buffer_jbd(bh), buffer_dirty(bh)); 264 265 if (buffer_jbd(bh)) { 266 continue; 267 } 268 269 if (ignore_cache) { 270 if (buffer_dirty(bh)) { 271 /* This should probably be a BUG, or 272 * at least return an error. */ 273 continue; 274 } 275 276 /* A read-ahead request was made - if the 277 * buffer is already under read-ahead from a 278 * previously submitted request than we are 279 * done here. */ 280 if ((flags & OCFS2_BH_READAHEAD) 281 && ocfs2_buffer_read_ahead(ci, bh)) 282 continue; 283 284 lock_buffer(bh); 285 if (buffer_jbd(bh)) { 286 #ifdef CATCH_BH_JBD_RACES 287 mlog(ML_ERROR, "block %llu had the JBD bit set " 288 "while I was in lock_buffer!", 289 (unsigned long long)bh->b_blocknr); 290 BUG(); 291 #else 292 unlock_buffer(bh); 293 continue; 294 #endif 295 } 296 297 /* Re-check ocfs2_buffer_uptodate() as a 298 * previously read-ahead buffer may have 299 * completed I/O while we were waiting for the 300 * buffer lock. */ 301 if (!(flags & OCFS2_BH_IGNORE_CACHE) 302 && !(flags & OCFS2_BH_READAHEAD) 303 && ocfs2_buffer_uptodate(ci, bh)) { 304 unlock_buffer(bh); 305 continue; 306 } 307 308 clear_buffer_uptodate(bh); 309 get_bh(bh); /* for end_buffer_read_sync() */ 310 if (validate) 311 set_buffer_needs_validate(bh); 312 bh->b_end_io = end_buffer_read_sync; 313 submit_bh(READ, bh); 314 continue; 315 } 316 } 317 318 status = 0; 319 320 for (i = (nr - 1); i >= 0; i--) { 321 bh = bhs[i]; 322 323 if (!(flags & OCFS2_BH_READAHEAD)) { 324 if (status) { 325 /* Clear the rest of the buffers on error */ 326 put_bh(bh); 327 bhs[i] = NULL; 328 continue; 329 } 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 trace_ocfs2_read_blocks_end((unsigned long long)block, nr, 372 flags, ignore_cache); 373 374 bail: 375 376 return status; 377 } 378 379 /* Check whether the blkno is the super block or one of the backups. */ 380 static void ocfs2_check_super_or_backup(struct super_block *sb, 381 sector_t blkno) 382 { 383 int i; 384 u64 backup_blkno; 385 386 if (blkno == OCFS2_SUPER_BLOCK_BLKNO) 387 return; 388 389 for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) { 390 backup_blkno = ocfs2_backup_super_blkno(sb, i); 391 if (backup_blkno == blkno) 392 return; 393 } 394 395 BUG(); 396 } 397 398 /* 399 * Write super block and backups doesn't need to collaborate with journal, 400 * so we don't need to lock ip_io_mutex and ci doesn't need to bea passed 401 * into this function. 402 */ 403 int ocfs2_write_super_or_backup(struct ocfs2_super *osb, 404 struct buffer_head *bh) 405 { 406 int ret = 0; 407 struct ocfs2_dinode *di = (struct ocfs2_dinode *)bh->b_data; 408 409 BUG_ON(buffer_jbd(bh)); 410 ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr); 411 412 if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) { 413 ret = -EROFS; 414 mlog_errno(ret); 415 goto out; 416 } 417 418 lock_buffer(bh); 419 set_buffer_uptodate(bh); 420 421 /* remove from dirty list before I/O. */ 422 clear_buffer_dirty(bh); 423 424 get_bh(bh); /* for end_buffer_write_sync() */ 425 bh->b_end_io = end_buffer_write_sync; 426 ocfs2_compute_meta_ecc(osb->sb, bh->b_data, &di->i_check); 427 submit_bh(WRITE, bh); 428 429 wait_on_buffer(bh); 430 431 if (!buffer_uptodate(bh)) { 432 ret = -EIO; 433 mlog_errno(ret); 434 } 435 436 out: 437 return ret; 438 } 439