1 /* 2 * High-level sync()-related operations 3 */ 4 5 #include <linux/kernel.h> 6 #include <linux/file.h> 7 #include <linux/fs.h> 8 #include <linux/slab.h> 9 #include <linux/module.h> 10 #include <linux/namei.h> 11 #include <linux/sched.h> 12 #include <linux/writeback.h> 13 #include <linux/syscalls.h> 14 #include <linux/linkage.h> 15 #include <linux/pagemap.h> 16 #include <linux/quotaops.h> 17 #include <linux/buffer_head.h> 18 #include <linux/backing-dev.h> 19 #include "internal.h" 20 21 #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \ 22 SYNC_FILE_RANGE_WAIT_AFTER) 23 24 /* 25 * Do the filesystem syncing work. For simple filesystems 26 * writeback_inodes_sb(sb) just dirties buffers with inodes so we have to 27 * submit IO for these buffers via __sync_blockdev(). This also speeds up the 28 * wait == 1 case since in that case write_inode() functions do 29 * sync_dirty_buffer() and thus effectively write one block at a time. 30 */ 31 static int __sync_filesystem(struct super_block *sb, int wait) 32 { 33 /* 34 * This should be safe, as we require bdi backing to actually 35 * write out data in the first place 36 */ 37 if (!sb->s_bdi || sb->s_bdi == &noop_backing_dev_info) 38 return 0; 39 40 if (sb->s_qcop && sb->s_qcop->quota_sync) 41 sb->s_qcop->quota_sync(sb, -1, wait); 42 43 if (wait) 44 sync_inodes_sb(sb); 45 else 46 writeback_inodes_sb(sb); 47 48 if (sb->s_op->sync_fs) 49 sb->s_op->sync_fs(sb, wait); 50 return __sync_blockdev(sb->s_bdev, wait); 51 } 52 53 /* 54 * Write out and wait upon all dirty data associated with this 55 * superblock. Filesystem data as well as the underlying block 56 * device. Takes the superblock lock. 57 */ 58 int sync_filesystem(struct super_block *sb) 59 { 60 int ret; 61 62 /* 63 * We need to be protected against the filesystem going from 64 * r/o to r/w or vice versa. 65 */ 66 WARN_ON(!rwsem_is_locked(&sb->s_umount)); 67 68 /* 69 * No point in syncing out anything if the filesystem is read-only. 70 */ 71 if (sb->s_flags & MS_RDONLY) 72 return 0; 73 74 ret = __sync_filesystem(sb, 0); 75 if (ret < 0) 76 return ret; 77 return __sync_filesystem(sb, 1); 78 } 79 EXPORT_SYMBOL_GPL(sync_filesystem); 80 81 static void sync_one_sb(struct super_block *sb, void *arg) 82 { 83 if (!(sb->s_flags & MS_RDONLY) && sb->s_bdi) 84 __sync_filesystem(sb, *(int *)arg); 85 } 86 /* 87 * Sync all the data for all the filesystems (called by sys_sync() and 88 * emergency sync) 89 */ 90 static void sync_filesystems(int wait) 91 { 92 iterate_supers(sync_one_sb, &wait); 93 } 94 95 /* 96 * sync everything. Start out by waking pdflush, because that writes back 97 * all queues in parallel. 98 */ 99 SYSCALL_DEFINE0(sync) 100 { 101 wakeup_flusher_threads(0); 102 sync_filesystems(0); 103 sync_filesystems(1); 104 if (unlikely(laptop_mode)) 105 laptop_sync_completion(); 106 return 0; 107 } 108 109 static void do_sync_work(struct work_struct *work) 110 { 111 /* 112 * Sync twice to reduce the possibility we skipped some inodes / pages 113 * because they were temporarily locked 114 */ 115 sync_filesystems(0); 116 sync_filesystems(0); 117 printk("Emergency Sync complete\n"); 118 kfree(work); 119 } 120 121 void emergency_sync(void) 122 { 123 struct work_struct *work; 124 125 work = kmalloc(sizeof(*work), GFP_ATOMIC); 126 if (work) { 127 INIT_WORK(work, do_sync_work); 128 schedule_work(work); 129 } 130 } 131 132 /* 133 * sync a single super 134 */ 135 SYSCALL_DEFINE1(syncfs, int, fd) 136 { 137 struct file *file; 138 struct super_block *sb; 139 int ret; 140 int fput_needed; 141 142 file = fget_light(fd, &fput_needed); 143 if (!file) 144 return -EBADF; 145 sb = file->f_dentry->d_sb; 146 147 down_read(&sb->s_umount); 148 ret = sync_filesystem(sb); 149 up_read(&sb->s_umount); 150 151 fput_light(file, fput_needed); 152 return ret; 153 } 154 155 /** 156 * vfs_fsync_range - helper to sync a range of data & metadata to disk 157 * @file: file to sync 158 * @start: offset in bytes of the beginning of data range to sync 159 * @end: offset in bytes of the end of data range (inclusive) 160 * @datasync: perform only datasync 161 * 162 * Write back data in range @start..@end and metadata for @file to disk. If 163 * @datasync is set only metadata needed to access modified file data is 164 * written. 165 */ 166 int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) 167 { 168 struct address_space *mapping = file->f_mapping; 169 int err, ret; 170 171 if (!file->f_op || !file->f_op->fsync) { 172 ret = -EINVAL; 173 goto out; 174 } 175 176 ret = filemap_write_and_wait_range(mapping, start, end); 177 178 /* 179 * We need to protect against concurrent writers, which could cause 180 * livelocks in fsync_buffers_list(). 181 */ 182 mutex_lock(&mapping->host->i_mutex); 183 err = file->f_op->fsync(file, datasync); 184 if (!ret) 185 ret = err; 186 mutex_unlock(&mapping->host->i_mutex); 187 188 out: 189 return ret; 190 } 191 EXPORT_SYMBOL(vfs_fsync_range); 192 193 /** 194 * vfs_fsync - perform a fsync or fdatasync on a file 195 * @file: file to sync 196 * @datasync: only perform a fdatasync operation 197 * 198 * Write back data and metadata for @file to disk. If @datasync is 199 * set only metadata needed to access modified file data is written. 200 */ 201 int vfs_fsync(struct file *file, int datasync) 202 { 203 return vfs_fsync_range(file, 0, LLONG_MAX, datasync); 204 } 205 EXPORT_SYMBOL(vfs_fsync); 206 207 static int do_fsync(unsigned int fd, int datasync) 208 { 209 struct file *file; 210 int ret = -EBADF; 211 212 file = fget(fd); 213 if (file) { 214 ret = vfs_fsync(file, datasync); 215 fput(file); 216 } 217 return ret; 218 } 219 220 SYSCALL_DEFINE1(fsync, unsigned int, fd) 221 { 222 return do_fsync(fd, 0); 223 } 224 225 SYSCALL_DEFINE1(fdatasync, unsigned int, fd) 226 { 227 return do_fsync(fd, 1); 228 } 229 230 /** 231 * generic_write_sync - perform syncing after a write if file / inode is sync 232 * @file: file to which the write happened 233 * @pos: offset where the write started 234 * @count: length of the write 235 * 236 * This is just a simple wrapper about our general syncing function. 237 */ 238 int generic_write_sync(struct file *file, loff_t pos, loff_t count) 239 { 240 if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host)) 241 return 0; 242 return vfs_fsync_range(file, pos, pos + count - 1, 243 (file->f_flags & __O_SYNC) ? 0 : 1); 244 } 245 EXPORT_SYMBOL(generic_write_sync); 246 247 /* 248 * sys_sync_file_range() permits finely controlled syncing over a segment of 249 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is 250 * zero then sys_sync_file_range() will operate from offset out to EOF. 251 * 252 * The flag bits are: 253 * 254 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range 255 * before performing the write. 256 * 257 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the 258 * range which are not presently under writeback. Note that this may block for 259 * significant periods due to exhaustion of disk request structures. 260 * 261 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range 262 * after performing the write. 263 * 264 * Useful combinations of the flag bits are: 265 * 266 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages 267 * in the range which were dirty on entry to sys_sync_file_range() are placed 268 * under writeout. This is a start-write-for-data-integrity operation. 269 * 270 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which 271 * are not presently under writeout. This is an asynchronous flush-to-disk 272 * operation. Not suitable for data integrity operations. 273 * 274 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for 275 * completion of writeout of all pages in the range. This will be used after an 276 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait 277 * for that operation to complete and to return the result. 278 * 279 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: 280 * a traditional sync() operation. This is a write-for-data-integrity operation 281 * which will ensure that all pages in the range which were dirty on entry to 282 * sys_sync_file_range() are committed to disk. 283 * 284 * 285 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any 286 * I/O errors or ENOSPC conditions and will return those to the caller, after 287 * clearing the EIO and ENOSPC flags in the address_space. 288 * 289 * It should be noted that none of these operations write out the file's 290 * metadata. So unless the application is strictly performing overwrites of 291 * already-instantiated disk blocks, there are no guarantees here that the data 292 * will be available after a crash. 293 */ 294 SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes, 295 unsigned int flags) 296 { 297 int ret; 298 struct file *file; 299 struct address_space *mapping; 300 loff_t endbyte; /* inclusive */ 301 int fput_needed; 302 umode_t i_mode; 303 304 ret = -EINVAL; 305 if (flags & ~VALID_FLAGS) 306 goto out; 307 308 endbyte = offset + nbytes; 309 310 if ((s64)offset < 0) 311 goto out; 312 if ((s64)endbyte < 0) 313 goto out; 314 if (endbyte < offset) 315 goto out; 316 317 if (sizeof(pgoff_t) == 4) { 318 if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 319 /* 320 * The range starts outside a 32 bit machine's 321 * pagecache addressing capabilities. Let it "succeed" 322 */ 323 ret = 0; 324 goto out; 325 } 326 if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 327 /* 328 * Out to EOF 329 */ 330 nbytes = 0; 331 } 332 } 333 334 if (nbytes == 0) 335 endbyte = LLONG_MAX; 336 else 337 endbyte--; /* inclusive */ 338 339 ret = -EBADF; 340 file = fget_light(fd, &fput_needed); 341 if (!file) 342 goto out; 343 344 i_mode = file->f_path.dentry->d_inode->i_mode; 345 ret = -ESPIPE; 346 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && 347 !S_ISLNK(i_mode)) 348 goto out_put; 349 350 mapping = file->f_mapping; 351 if (!mapping) { 352 ret = -EINVAL; 353 goto out_put; 354 } 355 356 ret = 0; 357 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { 358 ret = filemap_fdatawait_range(mapping, offset, endbyte); 359 if (ret < 0) 360 goto out_put; 361 } 362 363 if (flags & SYNC_FILE_RANGE_WRITE) { 364 ret = filemap_fdatawrite_range(mapping, offset, endbyte); 365 if (ret < 0) 366 goto out_put; 367 } 368 369 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) 370 ret = filemap_fdatawait_range(mapping, offset, endbyte); 371 372 out_put: 373 fput_light(file, fput_needed); 374 out: 375 return ret; 376 } 377 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS 378 asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes, 379 long flags) 380 { 381 return SYSC_sync_file_range((int) fd, offset, nbytes, 382 (unsigned int) flags); 383 } 384 SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range); 385 #endif 386 387 /* It would be nice if people remember that not all the world's an i386 388 when they introduce new system calls */ 389 SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags, 390 loff_t offset, loff_t nbytes) 391 { 392 return sys_sync_file_range(fd, offset, nbytes, flags); 393 } 394 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS 395 asmlinkage long SyS_sync_file_range2(long fd, long flags, 396 loff_t offset, loff_t nbytes) 397 { 398 return SYSC_sync_file_range2((int) fd, (unsigned int) flags, 399 offset, nbytes); 400 } 401 SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2); 402 #endif 403