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 42int 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 brelse(bh); 83 } 84 85 mutex_unlock(&OCFS2_I(inode)->ip_io_mutex); 86out: 87 mlog_exit(ret); 88 return ret; 89} 90 91int ocfs2_read_blocks(struct ocfs2_super *osb, u64 block, int nr, 92 struct buffer_head *bhs[], int flags, 93 struct inode *inode) 94{ 95 int status = 0; 96 struct super_block *sb; 97 int i, ignore_cache = 0; 98 struct buffer_head *bh; 99 100 mlog_entry("(block=(%llu), nr=(%d), flags=%d, inode=%p)\n", 101 (unsigned long long)block, nr, flags, inode); 102 103 BUG_ON((flags & OCFS2_BH_READAHEAD) && 104 (!inode || !(flags & OCFS2_BH_CACHED))); 105 106 if (osb == NULL || osb->sb == NULL || bhs == NULL) { 107 status = -EINVAL; 108 mlog_errno(status); 109 goto bail; 110 } 111 112 if (nr < 0) { 113 mlog(ML_ERROR, "asked to read %d blocks!\n", nr); 114 status = -EINVAL; 115 mlog_errno(status); 116 goto bail; 117 } 118 119 if (nr == 0) { 120 mlog(ML_BH_IO, "No buffers will be read!\n"); 121 status = 0; 122 goto bail; 123 } 124 125 sb = osb->sb; 126 127 if (flags & OCFS2_BH_CACHED && !inode) 128 flags &= ~OCFS2_BH_CACHED; 129 130 if (inode) 131 mutex_lock(&OCFS2_I(inode)->ip_io_mutex); 132 for (i = 0 ; i < nr ; i++) { 133 if (bhs[i] == NULL) { 134 bhs[i] = sb_getblk(sb, block++); 135 if (bhs[i] == NULL) { 136 if (inode) 137 mutex_unlock(&OCFS2_I(inode)->ip_io_mutex); 138 status = -EIO; 139 mlog_errno(status); 140 goto bail; 141 } 142 } 143 bh = bhs[i]; 144 ignore_cache = 0; 145 146 /* There are three read-ahead cases here which we need to 147 * be concerned with. All three assume a buffer has 148 * previously been submitted with OCFS2_BH_READAHEAD 149 * and it hasn't yet completed I/O. 150 * 151 * 1) The current request is sync to disk. This rarely 152 * happens these days, and never when performance 153 * matters - the code can just wait on the buffer 154 * lock and re-submit. 155 * 156 * 2) The current request is cached, but not 157 * readahead. ocfs2_buffer_uptodate() will return 158 * false anyway, so we'll wind up waiting on the 159 * buffer lock to do I/O. We re-check the request 160 * with after getting the lock to avoid a re-submit. 161 * 162 * 3) The current request is readahead (and so must 163 * also be a caching one). We short circuit if the 164 * buffer is locked (under I/O) and if it's in the 165 * uptodate cache. The re-check from #2 catches the 166 * case that the previous read-ahead completes just 167 * before our is-it-in-flight check. 168 */ 169 170 if (flags & OCFS2_BH_CACHED && 171 !ocfs2_buffer_uptodate(inode, bh)) { 172 mlog(ML_UPTODATE, 173 "bh (%llu), inode %llu not uptodate\n", 174 (unsigned long long)bh->b_blocknr, 175 (unsigned long long)OCFS2_I(inode)->ip_blkno); 176 ignore_cache = 1; 177 } 178 179 if (buffer_jbd(bh)) { 180 if (!(flags & OCFS2_BH_CACHED) || ignore_cache) 181 mlog(ML_BH_IO, "trying to sync read a jbd " 182 "managed bh (blocknr = %llu)\n", 183 (unsigned long long)bh->b_blocknr); 184 continue; 185 } 186 187 if (!(flags & OCFS2_BH_CACHED) || ignore_cache) { 188 if (buffer_dirty(bh)) { 189 /* This should probably be a BUG, or 190 * at least return an error. */ 191 mlog(ML_BH_IO, "asking me to sync read a dirty " 192 "buffer! (blocknr = %llu)\n", 193 (unsigned long long)bh->b_blocknr); 194 continue; 195 } 196 197 /* A read-ahead request was made - if the 198 * buffer is already under read-ahead from a 199 * previously submitted request than we are 200 * done here. */ 201 if ((flags & OCFS2_BH_READAHEAD) 202 && ocfs2_buffer_read_ahead(inode, bh)) 203 continue; 204 205 lock_buffer(bh); 206 if (buffer_jbd(bh)) { 207#ifdef CATCH_BH_JBD_RACES 208 mlog(ML_ERROR, "block %llu had the JBD bit set " 209 "while I was in lock_buffer!", 210 (unsigned long long)bh->b_blocknr); 211 BUG(); 212#else 213 unlock_buffer(bh); 214 continue; 215#endif 216 } 217 218 /* Re-check ocfs2_buffer_uptodate() as a 219 * previously read-ahead buffer may have 220 * completed I/O while we were waiting for the 221 * buffer lock. */ 222 if ((flags & OCFS2_BH_CACHED) 223 && !(flags & OCFS2_BH_READAHEAD) 224 && ocfs2_buffer_uptodate(inode, bh)) { 225 unlock_buffer(bh); 226 continue; 227 } 228 229 clear_buffer_uptodate(bh); 230 get_bh(bh); /* for end_buffer_read_sync() */ 231 bh->b_end_io = end_buffer_read_sync; 232 submit_bh(READ, bh); 233 continue; 234 } 235 } 236 237 status = 0; 238 239 for (i = (nr - 1); i >= 0; i--) { 240 bh = bhs[i]; 241 242 if (!(flags & OCFS2_BH_READAHEAD)) { 243 /* We know this can't have changed as we hold the 244 * inode sem. Avoid doing any work on the bh if the 245 * journal has it. */ 246 if (!buffer_jbd(bh)) 247 wait_on_buffer(bh); 248 249 if (!buffer_uptodate(bh)) { 250 /* Status won't be cleared from here on out, 251 * so we can safely record this and loop back 252 * to cleanup the other buffers. Don't need to 253 * remove the clustered uptodate information 254 * for this bh as it's not marked locally 255 * uptodate. */ 256 status = -EIO; 257 brelse(bh); 258 bhs[i] = NULL; 259 continue; 260 } 261 } 262 263 /* Always set the buffer in the cache, even if it was 264 * a forced read, or read-ahead which hasn't yet 265 * completed. */ 266 if (inode) 267 ocfs2_set_buffer_uptodate(inode, bh); 268 } 269 if (inode) 270 mutex_unlock(&OCFS2_I(inode)->ip_io_mutex); 271 272 mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s, flags=0x%x\n", 273 (unsigned long long)block, nr, 274 (!(flags & OCFS2_BH_CACHED) || ignore_cache) ? "no" : "yes", flags); 275 276bail: 277 278 mlog_exit(status); 279 return status; 280} 281