Andreas Dilger | 0f5eba7 | 2011-09-24 13:48:55 -0400 | [diff] [blame] | 1 | /* |
| 2 | * Helper functions for multiple mount protection (MMP). |
| 3 | * |
| 4 | * Copyright (C) 2011 Whamcloud, Inc. |
| 5 | * |
| 6 | * %Begin-Header% |
Andreas Dilger | ab00fda | 2012-11-22 15:29:15 -0700 | [diff] [blame] | 7 | * This file may be redistributed under the terms of the GNU Library |
| 8 | * General Public License, version 2. |
Andreas Dilger | 0f5eba7 | 2011-09-24 13:48:55 -0400 | [diff] [blame] | 9 | * %End-Header% |
| 10 | */ |
| 11 | |
| 12 | #ifndef _GNU_SOURCE |
| 13 | #define _GNU_SOURCE |
| 14 | #endif |
| 15 | |
Mike Frysinger | 997a0cf | 2012-02-27 01:12:53 -0500 | [diff] [blame] | 16 | #include "config.h" |
| 17 | |
Andreas Dilger | 0f5eba7 | 2011-09-24 13:48:55 -0400 | [diff] [blame] | 18 | #if HAVE_UNISTD_H |
| 19 | #include <unistd.h> |
| 20 | #endif |
| 21 | #include <sys/time.h> |
| 22 | |
| 23 | #include <sys/types.h> |
| 24 | #include <sys/stat.h> |
| 25 | #include <fcntl.h> |
| 26 | |
| 27 | #include "ext2fs/ext2_fs.h" |
| 28 | #include "ext2fs/ext2fs.h" |
| 29 | |
Andreas Dilger | 0f5eba7 | 2011-09-24 13:48:55 -0400 | [diff] [blame] | 30 | #ifndef O_DIRECT |
| 31 | #define O_DIRECT 0 |
| 32 | #endif |
| 33 | |
| 34 | errcode_t ext2fs_mmp_read(ext2_filsys fs, blk64_t mmp_blk, void *buf) |
| 35 | { |
| 36 | struct mmp_struct *mmp_cmp; |
| 37 | errcode_t retval = 0; |
| 38 | |
| 39 | if ((mmp_blk <= fs->super->s_first_data_block) || |
| 40 | (mmp_blk >= fs->super->s_blocks_count)) |
| 41 | return EXT2_ET_MMP_BAD_BLOCK; |
| 42 | |
Andreas Dilger | 0f5eba7 | 2011-09-24 13:48:55 -0400 | [diff] [blame] | 43 | /* ext2fs_open() reserves fd0,1,2 to avoid stdio collision, so checking |
| 44 | * mmp_fd <= 0 is OK to validate that the fd is valid. This opens its |
| 45 | * own fd to read the MMP block to ensure that it is using O_DIRECT, |
| 46 | * regardless of how the io_manager is doing reads, to avoid caching of |
| 47 | * the MMP block by the io_manager or the VM. It needs to be fresh. */ |
| 48 | if (fs->mmp_fd <= 0) { |
| 49 | fs->mmp_fd = open(fs->device_name, O_RDWR | O_DIRECT); |
| 50 | if (fs->mmp_fd < 0) { |
| 51 | retval = EXT2_ET_MMP_OPEN_DIRECT; |
| 52 | goto out; |
| 53 | } |
| 54 | } |
| 55 | |
Theodore Ts'o | dd0a267 | 2012-05-07 13:25:44 -0400 | [diff] [blame] | 56 | if (fs->mmp_cmp == NULL) { |
| 57 | int align = ext2fs_get_dio_alignment(fs->mmp_fd); |
| 58 | |
| 59 | retval = ext2fs_get_memalign(fs->blocksize, align, |
| 60 | &fs->mmp_cmp); |
| 61 | if (retval) |
| 62 | return retval; |
| 63 | } |
| 64 | |
Theodore Ts'o | e48bf25 | 2013-05-19 18:50:10 -0400 | [diff] [blame] | 65 | if ((blk64_t) ext2fs_llseek(fs->mmp_fd, mmp_blk * fs->blocksize, |
| 66 | SEEK_SET) != |
Andreas Dilger | 0f5eba7 | 2011-09-24 13:48:55 -0400 | [diff] [blame] | 67 | mmp_blk * fs->blocksize) { |
| 68 | retval = EXT2_ET_LLSEEK_FAILED; |
| 69 | goto out; |
| 70 | } |
| 71 | |
| 72 | if (read(fs->mmp_fd, fs->mmp_cmp, fs->blocksize) != fs->blocksize) { |
| 73 | retval = EXT2_ET_SHORT_READ; |
| 74 | goto out; |
| 75 | } |
| 76 | |
| 77 | mmp_cmp = fs->mmp_cmp; |
Darrick J. Wong | 9026b3d | 2011-09-30 12:41:26 -0700 | [diff] [blame] | 78 | #ifdef WORDS_BIGENDIAN |
| 79 | ext2fs_swap_mmp(mmp_cmp); |
Andreas Dilger | 0f5eba7 | 2011-09-24 13:48:55 -0400 | [diff] [blame] | 80 | #endif |
| 81 | |
| 82 | if (buf != NULL && buf != fs->mmp_cmp) |
| 83 | memcpy(buf, fs->mmp_cmp, fs->blocksize); |
| 84 | |
| 85 | if (mmp_cmp->mmp_magic != EXT4_MMP_MAGIC) { |
| 86 | retval = EXT2_ET_MMP_MAGIC_INVALID; |
| 87 | goto out; |
| 88 | } |
| 89 | |
| 90 | out: |
| 91 | return retval; |
| 92 | } |
| 93 | |
| 94 | errcode_t ext2fs_mmp_write(ext2_filsys fs, blk64_t mmp_blk, void *buf) |
| 95 | { |
| 96 | struct mmp_struct *mmp_s = buf; |
| 97 | struct timeval tv; |
| 98 | errcode_t retval = 0; |
| 99 | |
| 100 | gettimeofday(&tv, 0); |
| 101 | mmp_s->mmp_time = tv.tv_sec; |
| 102 | fs->mmp_last_written = tv.tv_sec; |
| 103 | |
| 104 | if (fs->super->s_mmp_block < fs->super->s_first_data_block || |
| 105 | fs->super->s_mmp_block > ext2fs_blocks_count(fs->super)) |
| 106 | return EXT2_ET_MMP_BAD_BLOCK; |
| 107 | |
Darrick J. Wong | 9026b3d | 2011-09-30 12:41:26 -0700 | [diff] [blame] | 108 | #ifdef WORDS_BIGENDIAN |
| 109 | ext2fs_swap_mmp(mmp_s); |
Andreas Dilger | 0f5eba7 | 2011-09-24 13:48:55 -0400 | [diff] [blame] | 110 | #endif |
| 111 | |
| 112 | /* I was tempted to make this use O_DIRECT and the mmp_fd, but |
| 113 | * this caused no end of grief, while leaving it as-is works. */ |
Eric Sandeen | df7a86d | 2011-11-11 21:06:04 -0500 | [diff] [blame] | 114 | retval = io_channel_write_blk64(fs->io, mmp_blk, -(int)sizeof(struct mmp_struct), buf); |
Andreas Dilger | 0f5eba7 | 2011-09-24 13:48:55 -0400 | [diff] [blame] | 115 | |
Darrick J. Wong | 9026b3d | 2011-09-30 12:41:26 -0700 | [diff] [blame] | 116 | #ifdef WORDS_BIGENDIAN |
| 117 | ext2fs_swap_mmp(mmp_s); |
Andreas Dilger | 0f5eba7 | 2011-09-24 13:48:55 -0400 | [diff] [blame] | 118 | #endif |
| 119 | |
| 120 | /* Make sure the block gets to disk quickly */ |
| 121 | io_channel_flush(fs->io); |
| 122 | return retval; |
| 123 | } |
| 124 | |
| 125 | #ifdef HAVE_SRANDOM |
| 126 | #define srand(x) srandom(x) |
| 127 | #define rand() random() |
| 128 | #endif |
| 129 | |
| 130 | unsigned ext2fs_mmp_new_seq() |
| 131 | { |
| 132 | unsigned new_seq; |
| 133 | struct timeval tv; |
| 134 | |
| 135 | gettimeofday(&tv, 0); |
| 136 | srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec); |
| 137 | |
| 138 | gettimeofday(&tv, 0); |
| 139 | /* Crank the random number generator a few times */ |
| 140 | for (new_seq = (tv.tv_sec ^ tv.tv_usec) & 0x1F; new_seq > 0; new_seq--) |
| 141 | rand(); |
| 142 | |
| 143 | do { |
| 144 | new_seq = rand(); |
| 145 | } while (new_seq > EXT4_MMP_SEQ_MAX); |
| 146 | |
| 147 | return new_seq; |
| 148 | } |
| 149 | |
| 150 | static errcode_t ext2fs_mmp_reset(ext2_filsys fs) |
| 151 | { |
| 152 | struct mmp_struct *mmp_s = NULL; |
| 153 | errcode_t retval = 0; |
| 154 | |
| 155 | if (fs->mmp_buf == NULL) { |
| 156 | retval = ext2fs_get_mem(fs->blocksize, &fs->mmp_buf); |
| 157 | if (retval) |
| 158 | goto out; |
| 159 | } |
| 160 | |
| 161 | memset(fs->mmp_buf, 0, fs->blocksize); |
| 162 | mmp_s = fs->mmp_buf; |
| 163 | |
| 164 | mmp_s->mmp_magic = EXT4_MMP_MAGIC; |
| 165 | mmp_s->mmp_seq = EXT4_MMP_SEQ_CLEAN; |
| 166 | mmp_s->mmp_time = 0; |
| 167 | #if _BSD_SOURCE || _XOPEN_SOURCE >= 500 |
| 168 | gethostname(mmp_s->mmp_nodename, sizeof(mmp_s->mmp_nodename)); |
| 169 | #else |
| 170 | mmp_s->mmp_nodename[0] = '\0'; |
| 171 | #endif |
| 172 | strncpy(mmp_s->mmp_bdevname, fs->device_name, |
| 173 | sizeof(mmp_s->mmp_bdevname)); |
| 174 | |
| 175 | mmp_s->mmp_check_interval = fs->super->s_mmp_update_interval; |
| 176 | if (mmp_s->mmp_check_interval < EXT4_MMP_MIN_CHECK_INTERVAL) |
| 177 | mmp_s->mmp_check_interval = EXT4_MMP_MIN_CHECK_INTERVAL; |
| 178 | |
| 179 | retval = ext2fs_mmp_write(fs, fs->super->s_mmp_block, fs->mmp_buf); |
| 180 | out: |
| 181 | return retval; |
| 182 | } |
| 183 | |
| 184 | errcode_t ext2fs_mmp_clear(ext2_filsys fs) |
| 185 | { |
| 186 | errcode_t retval = 0; |
| 187 | |
| 188 | if (!(fs->flags & EXT2_FLAG_RW)) |
| 189 | return EXT2_ET_RO_FILSYS; |
| 190 | |
| 191 | retval = ext2fs_mmp_reset(fs); |
| 192 | |
| 193 | return retval; |
| 194 | } |
| 195 | |
| 196 | errcode_t ext2fs_mmp_init(ext2_filsys fs) |
| 197 | { |
| 198 | struct ext2_super_block *sb = fs->super; |
| 199 | blk64_t mmp_block; |
| 200 | errcode_t retval; |
| 201 | |
| 202 | if (sb->s_mmp_update_interval == 0) |
| 203 | sb->s_mmp_update_interval = EXT4_MMP_UPDATE_INTERVAL; |
| 204 | /* This is probably excessively large, but who knows? */ |
| 205 | else if (sb->s_mmp_update_interval > EXT4_MMP_MAX_UPDATE_INTERVAL) |
| 206 | return EXT2_ET_INVALID_ARGUMENT; |
| 207 | |
| 208 | if (fs->mmp_buf == NULL) { |
| 209 | retval = ext2fs_get_mem(fs->blocksize, &fs->mmp_buf); |
| 210 | if (retval) |
| 211 | goto out; |
| 212 | } |
| 213 | |
| 214 | retval = ext2fs_alloc_block2(fs, 0, fs->mmp_buf, &mmp_block); |
| 215 | if (retval) |
| 216 | goto out; |
| 217 | |
| 218 | sb->s_mmp_block = mmp_block; |
| 219 | |
| 220 | retval = ext2fs_mmp_reset(fs); |
| 221 | if (retval) |
| 222 | goto out; |
| 223 | |
| 224 | out: |
| 225 | return retval; |
| 226 | } |
| 227 | |
| 228 | /* |
| 229 | * Make sure that the fs is not mounted or being fsck'ed while opening the fs. |
| 230 | */ |
| 231 | errcode_t ext2fs_mmp_start(ext2_filsys fs) |
| 232 | { |
| 233 | struct mmp_struct *mmp_s; |
| 234 | unsigned seq; |
| 235 | unsigned int mmp_check_interval; |
| 236 | errcode_t retval = 0; |
| 237 | |
| 238 | if (fs->mmp_buf == NULL) { |
| 239 | retval = ext2fs_get_mem(fs->blocksize, &fs->mmp_buf); |
| 240 | if (retval) |
| 241 | goto mmp_error; |
| 242 | } |
| 243 | |
| 244 | retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, fs->mmp_buf); |
| 245 | if (retval) |
| 246 | goto mmp_error; |
| 247 | |
| 248 | mmp_s = fs->mmp_buf; |
| 249 | |
| 250 | mmp_check_interval = fs->super->s_mmp_update_interval; |
| 251 | if (mmp_check_interval < EXT4_MMP_MIN_CHECK_INTERVAL) |
| 252 | mmp_check_interval = EXT4_MMP_MIN_CHECK_INTERVAL; |
| 253 | |
| 254 | seq = mmp_s->mmp_seq; |
| 255 | if (seq == EXT4_MMP_SEQ_CLEAN) |
| 256 | goto clean_seq; |
| 257 | if (seq == EXT4_MMP_SEQ_FSCK) { |
| 258 | retval = EXT2_ET_MMP_FSCK_ON; |
| 259 | goto mmp_error; |
| 260 | } |
| 261 | |
| 262 | if (seq > EXT4_MMP_SEQ_FSCK) { |
| 263 | retval = EXT2_ET_MMP_UNKNOWN_SEQ; |
| 264 | goto mmp_error; |
| 265 | } |
| 266 | |
| 267 | /* |
| 268 | * If check_interval in MMP block is larger, use that instead of |
| 269 | * check_interval from the superblock. |
| 270 | */ |
| 271 | if (mmp_s->mmp_check_interval > mmp_check_interval) |
| 272 | mmp_check_interval = mmp_s->mmp_check_interval; |
| 273 | |
| 274 | sleep(2 * mmp_check_interval + 1); |
| 275 | |
| 276 | retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, fs->mmp_buf); |
| 277 | if (retval) |
| 278 | goto mmp_error; |
| 279 | |
| 280 | if (seq != mmp_s->mmp_seq) { |
| 281 | retval = EXT2_ET_MMP_FAILED; |
| 282 | goto mmp_error; |
| 283 | } |
| 284 | |
| 285 | clean_seq: |
| 286 | if (!(fs->flags & EXT2_FLAG_RW)) |
| 287 | goto mmp_error; |
| 288 | |
| 289 | mmp_s->mmp_seq = seq = ext2fs_mmp_new_seq(); |
| 290 | #if _BSD_SOURCE || _XOPEN_SOURCE >= 500 |
| 291 | gethostname(mmp_s->mmp_nodename, sizeof(mmp_s->mmp_nodename)); |
| 292 | #else |
| 293 | strcpy(mmp_s->mmp_nodename, "unknown host"); |
| 294 | #endif |
| 295 | strncpy(mmp_s->mmp_bdevname, fs->device_name, |
| 296 | sizeof(mmp_s->mmp_bdevname)); |
| 297 | |
| 298 | retval = ext2fs_mmp_write(fs, fs->super->s_mmp_block, fs->mmp_buf); |
| 299 | if (retval) |
| 300 | goto mmp_error; |
| 301 | |
| 302 | sleep(2 * mmp_check_interval + 1); |
| 303 | |
| 304 | retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, fs->mmp_buf); |
| 305 | if (retval) |
| 306 | goto mmp_error; |
| 307 | |
| 308 | if (seq != mmp_s->mmp_seq) { |
| 309 | retval = EXT2_ET_MMP_FAILED; |
| 310 | goto mmp_error; |
| 311 | } |
| 312 | |
| 313 | mmp_s->mmp_seq = EXT4_MMP_SEQ_FSCK; |
| 314 | retval = ext2fs_mmp_write(fs, fs->super->s_mmp_block, fs->mmp_buf); |
| 315 | if (retval) |
| 316 | goto mmp_error; |
| 317 | |
| 318 | return 0; |
| 319 | |
| 320 | mmp_error: |
| 321 | return retval; |
| 322 | } |
| 323 | |
| 324 | /* |
| 325 | * Clear the MMP usage in the filesystem. If this function returns an |
| 326 | * error EXT2_ET_MMP_CHANGE_ABORT it means the filesystem was modified |
| 327 | * by some other process while in use, and changes should be dropped, or |
| 328 | * risk filesystem corruption. |
| 329 | */ |
| 330 | errcode_t ext2fs_mmp_stop(ext2_filsys fs) |
| 331 | { |
| 332 | struct mmp_struct *mmp, *mmp_cmp; |
| 333 | errcode_t retval = 0; |
| 334 | |
| 335 | if (!(fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_MMP) || |
| 336 | !(fs->flags & EXT2_FLAG_RW) || (fs->flags & EXT2_FLAG_SKIP_MMP)) |
| 337 | goto mmp_error; |
| 338 | |
| 339 | retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, fs->mmp_buf); |
| 340 | if (retval) |
| 341 | goto mmp_error; |
| 342 | |
| 343 | /* Check if the MMP block is not changed. */ |
| 344 | mmp = fs->mmp_buf; |
| 345 | mmp_cmp = fs->mmp_cmp; |
| 346 | if (memcmp(mmp, mmp_cmp, sizeof(*mmp_cmp))) { |
| 347 | retval = EXT2_ET_MMP_CHANGE_ABORT; |
| 348 | goto mmp_error; |
| 349 | } |
| 350 | |
| 351 | mmp_cmp->mmp_seq = EXT4_MMP_SEQ_CLEAN; |
| 352 | retval = ext2fs_mmp_write(fs, fs->super->s_mmp_block, fs->mmp_cmp); |
| 353 | |
| 354 | mmp_error: |
| 355 | if (fs->mmp_fd > 0) { |
| 356 | close(fs->mmp_fd); |
| 357 | fs->mmp_fd = -1; |
| 358 | } |
| 359 | |
| 360 | return retval; |
| 361 | } |
| 362 | |
| 363 | #define EXT2_MIN_MMP_UPDATE_INTERVAL 60 |
| 364 | |
| 365 | /* |
| 366 | * Update the on-disk mmp buffer, after checking that it hasn't been changed. |
| 367 | */ |
| 368 | errcode_t ext2fs_mmp_update(ext2_filsys fs) |
| 369 | { |
| 370 | struct mmp_struct *mmp, *mmp_cmp; |
| 371 | struct timeval tv; |
| 372 | errcode_t retval = 0; |
| 373 | |
| 374 | if (!(fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_MMP) || |
| 375 | !(fs->flags & EXT2_FLAG_RW) || (fs->flags & EXT2_FLAG_SKIP_MMP)) |
| 376 | return 0; |
| 377 | |
| 378 | gettimeofday(&tv, 0); |
| 379 | if (tv.tv_sec - fs->mmp_last_written < EXT2_MIN_MMP_UPDATE_INTERVAL) |
| 380 | return 0; |
| 381 | |
| 382 | retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, NULL); |
| 383 | if (retval) |
| 384 | goto mmp_error; |
| 385 | |
| 386 | mmp = fs->mmp_buf; |
| 387 | mmp_cmp = fs->mmp_cmp; |
| 388 | |
| 389 | if (memcmp(mmp, mmp_cmp, sizeof(*mmp_cmp))) |
| 390 | return EXT2_ET_MMP_CHANGE_ABORT; |
| 391 | |
| 392 | mmp->mmp_time = tv.tv_sec; |
| 393 | mmp->mmp_seq = EXT4_MMP_SEQ_FSCK; |
| 394 | retval = ext2fs_mmp_write(fs, fs->super->s_mmp_block, fs->mmp_buf); |
| 395 | |
| 396 | mmp_error: |
| 397 | return retval; |
| 398 | } |