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/sched.h> 11 #include <linux/writeback.h> 12 #include <linux/syscalls.h> 13 #include <linux/linkage.h> 14 #include <linux/pagemap.h> 15 #include <linux/quotaops.h> 16 #include <linux/buffer_head.h> 17 #include <linux/backing-dev.h> 18 #include "internal.h" 19 20 #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \ 21 SYNC_FILE_RANGE_WAIT_AFTER) 22 23 /* 24 * Do the filesystem syncing work. For simple filesystems 25 * writeback_inodes_sb(sb) just dirties buffers with inodes so we have to 26 * submit IO for these buffers via __sync_blockdev(). This also speeds up the 27 * wait == 1 case since in that case write_inode() functions do 28 * sync_dirty_buffer() and thus effectively write one block at a time. 29 */ 30 static int __sync_filesystem(struct super_block *sb, int wait) 31 { 32 /* 33 * This should be safe, as we require bdi backing to actually 34 * write out data in the first place 35 */ 36 if (!sb->s_bdi || sb->s_bdi == &noop_backing_dev_info) 37 return 0; 38 39 if (sb->s_qcop && sb->s_qcop->quota_sync) 40 sb->s_qcop->quota_sync(sb, -1, wait); 41 42 if (wait) 43 sync_inodes_sb(sb); 44 else 45 writeback_inodes_sb(sb); 46 47 if (sb->s_op->sync_fs) 48 sb->s_op->sync_fs(sb, wait); 49 return __sync_blockdev(sb->s_bdev, wait); 50 } 51 52 /* 53 * Write out and wait upon all dirty data associated with this 54 * superblock. Filesystem data as well as the underlying block 55 * device. Takes the superblock lock. 56 */ 57 int sync_filesystem(struct super_block *sb) 58 { 59 int ret; 60 61 /* 62 * We need to be protected against the filesystem going from 63 * r/o to r/w or vice versa. 64 */ 65 WARN_ON(!rwsem_is_locked(&sb->s_umount)); 66 67 /* 68 * No point in syncing out anything if the filesystem is read-only. 69 */ 70 if (sb->s_flags & MS_RDONLY) 71 return 0; 72 73 ret = __sync_filesystem(sb, 0); 74 if (ret < 0) 75 return ret; 76 return __sync_filesystem(sb, 1); 77 } 78 EXPORT_SYMBOL_GPL(sync_filesystem); 79 80 static void sync_one_sb(struct super_block *sb, void *arg) 81 { 82 if (!(sb->s_flags & MS_RDONLY) && sb->s_bdi) 83 __sync_filesystem(sb, *(int *)arg); 84 } 85 /* 86 * Sync all the data for all the filesystems (called by sys_sync() and 87 * emergency sync) 88 */ 89 static void sync_filesystems(int wait) 90 { 91 iterate_supers(sync_one_sb, &wait); 92 } 93 94 /* 95 * sync everything. Start out by waking pdflush, because that writes back 96 * all queues in parallel. 97 */ 98 SYSCALL_DEFINE0(sync) 99 { 100 wakeup_flusher_threads(0); 101 sync_filesystems(0); 102 sync_filesystems(1); 103 if (unlikely(laptop_mode)) 104 laptop_sync_completion(); 105 return 0; 106 } 107 108 static void do_sync_work(struct work_struct *work) 109 { 110 /* 111 * Sync twice to reduce the possibility we skipped some inodes / pages 112 * because they were temporarily locked 113 */ 114 sync_filesystems(0); 115 sync_filesystems(0); 116 printk("Emergency Sync complete\n"); 117 kfree(work); 118 } 119 120 void emergency_sync(void) 121 { 122 struct work_struct *work; 123 124 work = kmalloc(sizeof(*work), GFP_ATOMIC); 125 if (work) { 126 INIT_WORK(work, do_sync_work); 127 schedule_work(work); 128 } 129 } 130 131 /* 132 * Generic function to fsync a file. 133 */ 134 int file_fsync(struct file *filp, int datasync) 135 { 136 struct inode *inode = filp->f_mapping->host; 137 struct super_block * sb; 138 int ret, err; 139 140 /* sync the inode to buffers */ 141 ret = write_inode_now(inode, 0); 142 143 /* sync the superblock to buffers */ 144 sb = inode->i_sb; 145 if (sb->s_dirt && sb->s_op->write_super) 146 sb->s_op->write_super(sb); 147 148 /* .. finally sync the buffers to disk */ 149 err = sync_blockdev(sb->s_bdev); 150 if (!ret) 151 ret = err; 152 return ret; 153 } 154 EXPORT_SYMBOL(file_fsync); 155 156 /** 157 * vfs_fsync_range - helper to sync a range of data & metadata to disk 158 * @file: file to sync 159 * @start: offset in bytes of the beginning of data range to sync 160 * @end: offset in bytes of the end of data range (inclusive) 161 * @datasync: perform only datasync 162 * 163 * Write back data in range @start..@end and metadata for @file to disk. If 164 * @datasync is set only metadata needed to access modified file data is 165 * written. 166 */ 167 int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) 168 { 169 struct address_space *mapping = file->f_mapping; 170 int err, ret; 171 172 if (!file->f_op || !file->f_op->fsync) { 173 ret = -EINVAL; 174 goto out; 175 } 176 177 ret = filemap_write_and_wait_range(mapping, start, end); 178 179 /* 180 * We need to protect against concurrent writers, which could cause 181 * livelocks in fsync_buffers_list(). 182 */ 183 mutex_lock(&mapping->host->i_mutex); 184 err = file->f_op->fsync(file, datasync); 185 if (!ret) 186 ret = err; 187 mutex_unlock(&mapping->host->i_mutex); 188 189 out: 190 return ret; 191 } 192 EXPORT_SYMBOL(vfs_fsync_range); 193 194 /** 195 * vfs_fsync - perform a fsync or fdatasync on a file 196 * @file: file to sync 197 * @datasync: only perform a fdatasync operation 198 * 199 * Write back data and metadata for @file to disk. If @datasync is 200 * set only metadata needed to access modified file data is written. 201 */ 202 int vfs_fsync(struct file *file, int datasync) 203 { 204 return vfs_fsync_range(file, 0, LLONG_MAX, datasync); 205 } 206 EXPORT_SYMBOL(vfs_fsync); 207 208 static int do_fsync(unsigned int fd, int datasync) 209 { 210 struct file *file; 211 int ret = -EBADF; 212 213 file = fget(fd); 214 if (file) { 215 ret = vfs_fsync(file, datasync); 216 fput(file); 217 } 218 return ret; 219 } 220 221 SYSCALL_DEFINE1(fsync, unsigned int, fd) 222 { 223 return do_fsync(fd, 0); 224 } 225 226 SYSCALL_DEFINE1(fdatasync, unsigned int, fd) 227 { 228 return do_fsync(fd, 1); 229 } 230 231 /** 232 * generic_write_sync - perform syncing after a write if file / inode is sync 233 * @file: file to which the write happened 234 * @pos: offset where the write started 235 * @count: length of the write 236 * 237 * This is just a simple wrapper about our general syncing function. 238 */ 239 int generic_write_sync(struct file *file, loff_t pos, loff_t count) 240 { 241 if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host)) 242 return 0; 243 return vfs_fsync_range(file, pos, pos + count - 1, 244 (file->f_flags & __O_SYNC) ? 0 : 1); 245 } 246 EXPORT_SYMBOL(generic_write_sync); 247 248 /* 249 * sys_sync_file_range() permits finely controlled syncing over a segment of 250 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is 251 * zero then sys_sync_file_range() will operate from offset out to EOF. 252 * 253 * The flag bits are: 254 * 255 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range 256 * before performing the write. 257 * 258 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the 259 * range which are not presently under writeback. Note that this may block for 260 * significant periods due to exhaustion of disk request structures. 261 * 262 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range 263 * after performing the write. 264 * 265 * Useful combinations of the flag bits are: 266 * 267 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages 268 * in the range which were dirty on entry to sys_sync_file_range() are placed 269 * under writeout. This is a start-write-for-data-integrity operation. 270 * 271 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which 272 * are not presently under writeout. This is an asynchronous flush-to-disk 273 * operation. Not suitable for data integrity operations. 274 * 275 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for 276 * completion of writeout of all pages in the range. This will be used after an 277 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait 278 * for that operation to complete and to return the result. 279 * 280 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: 281 * a traditional sync() operation. This is a write-for-data-integrity operation 282 * which will ensure that all pages in the range which were dirty on entry to 283 * sys_sync_file_range() are committed to disk. 284 * 285 * 286 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any 287 * I/O errors or ENOSPC conditions and will return those to the caller, after 288 * clearing the EIO and ENOSPC flags in the address_space. 289 * 290 * It should be noted that none of these operations write out the file's 291 * metadata. So unless the application is strictly performing overwrites of 292 * already-instantiated disk blocks, there are no guarantees here that the data 293 * will be available after a crash. 294 */ 295 SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes, 296 unsigned int flags) 297 { 298 int ret; 299 struct file *file; 300 struct address_space *mapping; 301 loff_t endbyte; /* inclusive */ 302 int fput_needed; 303 umode_t i_mode; 304 305 ret = -EINVAL; 306 if (flags & ~VALID_FLAGS) 307 goto out; 308 309 endbyte = offset + nbytes; 310 311 if ((s64)offset < 0) 312 goto out; 313 if ((s64)endbyte < 0) 314 goto out; 315 if (endbyte < offset) 316 goto out; 317 318 if (sizeof(pgoff_t) == 4) { 319 if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 320 /* 321 * The range starts outside a 32 bit machine's 322 * pagecache addressing capabilities. Let it "succeed" 323 */ 324 ret = 0; 325 goto out; 326 } 327 if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 328 /* 329 * Out to EOF 330 */ 331 nbytes = 0; 332 } 333 } 334 335 if (nbytes == 0) 336 endbyte = LLONG_MAX; 337 else 338 endbyte--; /* inclusive */ 339 340 ret = -EBADF; 341 file = fget_light(fd, &fput_needed); 342 if (!file) 343 goto out; 344 345 i_mode = file->f_path.dentry->d_inode->i_mode; 346 ret = -ESPIPE; 347 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && 348 !S_ISLNK(i_mode)) 349 goto out_put; 350 351 mapping = file->f_mapping; 352 if (!mapping) { 353 ret = -EINVAL; 354 goto out_put; 355 } 356 357 ret = 0; 358 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { 359 ret = filemap_fdatawait_range(mapping, offset, endbyte); 360 if (ret < 0) 361 goto out_put; 362 } 363 364 if (flags & SYNC_FILE_RANGE_WRITE) { 365 ret = filemap_fdatawrite_range(mapping, offset, endbyte); 366 if (ret < 0) 367 goto out_put; 368 } 369 370 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) 371 ret = filemap_fdatawait_range(mapping, offset, endbyte); 372 373 out_put: 374 fput_light(file, fput_needed); 375 out: 376 return ret; 377 } 378 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS 379 asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes, 380 long flags) 381 { 382 return SYSC_sync_file_range((int) fd, offset, nbytes, 383 (unsigned int) flags); 384 } 385 SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range); 386 #endif 387 388 /* It would be nice if people remember that not all the world's an i386 389 when they introduce new system calls */ 390 SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags, 391 loff_t offset, loff_t nbytes) 392 { 393 return sys_sync_file_range(fd, offset, nbytes, flags); 394 } 395 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS 396 asmlinkage long SyS_sync_file_range2(long fd, long flags, 397 loff_t offset, loff_t nbytes) 398 { 399 return SYSC_sync_file_range2((int) fd, (unsigned int) flags, 400 offset, nbytes); 401 } 402 SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2); 403 #endif 404