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_locked(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 * filp may be NULL if called via the msync of a vma. 135 */ 136 int file_fsync(struct file *filp, struct dentry *dentry, int datasync) 137 { 138 struct inode * inode = dentry->d_inode; 139 struct super_block * sb; 140 int ret, err; 141 142 /* sync the inode to buffers */ 143 ret = write_inode_now(inode, 0); 144 145 /* sync the superblock to buffers */ 146 sb = inode->i_sb; 147 if (sb->s_dirt && sb->s_op->write_super) 148 sb->s_op->write_super(sb); 149 150 /* .. finally sync the buffers to disk */ 151 err = sync_blockdev(sb->s_bdev); 152 if (!ret) 153 ret = err; 154 return ret; 155 } 156 EXPORT_SYMBOL(file_fsync); 157 158 /** 159 * vfs_fsync_range - helper to sync a range of data & metadata to disk 160 * @file: file to sync 161 * @start: offset in bytes of the beginning of data range to sync 162 * @end: offset in bytes of the end of data range (inclusive) 163 * @datasync: perform only datasync 164 * 165 * Write back data in range @start..@end and metadata for @file to disk. If 166 * @datasync is set only metadata needed to access modified file data is 167 * written. 168 */ 169 int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) 170 { 171 struct address_space *mapping = file->f_mapping; 172 int err, ret; 173 174 if (!file->f_op || !file->f_op->fsync) { 175 ret = -EINVAL; 176 goto out; 177 } 178 179 ret = filemap_write_and_wait_range(mapping, start, end); 180 181 /* 182 * We need to protect against concurrent writers, which could cause 183 * livelocks in fsync_buffers_list(). 184 */ 185 mutex_lock(&mapping->host->i_mutex); 186 err = file->f_op->fsync(file, file->f_path.dentry, datasync); 187 if (!ret) 188 ret = err; 189 mutex_unlock(&mapping->host->i_mutex); 190 191 out: 192 return ret; 193 } 194 EXPORT_SYMBOL(vfs_fsync_range); 195 196 /** 197 * vfs_fsync - perform a fsync or fdatasync on a file 198 * @file: file to sync 199 * @datasync: only perform a fdatasync operation 200 * 201 * Write back data and metadata for @file to disk. If @datasync is 202 * set only metadata needed to access modified file data is written. 203 */ 204 int vfs_fsync(struct file *file, int datasync) 205 { 206 return vfs_fsync_range(file, 0, LLONG_MAX, datasync); 207 } 208 EXPORT_SYMBOL(vfs_fsync); 209 210 static int do_fsync(unsigned int fd, int datasync) 211 { 212 struct file *file; 213 int ret = -EBADF; 214 215 file = fget(fd); 216 if (file) { 217 ret = vfs_fsync(file, datasync); 218 fput(file); 219 } 220 return ret; 221 } 222 223 SYSCALL_DEFINE1(fsync, unsigned int, fd) 224 { 225 return do_fsync(fd, 0); 226 } 227 228 SYSCALL_DEFINE1(fdatasync, unsigned int, fd) 229 { 230 return do_fsync(fd, 1); 231 } 232 233 /** 234 * generic_write_sync - perform syncing after a write if file / inode is sync 235 * @file: file to which the write happened 236 * @pos: offset where the write started 237 * @count: length of the write 238 * 239 * This is just a simple wrapper about our general syncing function. 240 */ 241 int generic_write_sync(struct file *file, loff_t pos, loff_t count) 242 { 243 if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host)) 244 return 0; 245 return vfs_fsync_range(file, pos, pos + count - 1, 246 (file->f_flags & __O_SYNC) ? 0 : 1); 247 } 248 EXPORT_SYMBOL(generic_write_sync); 249 250 /* 251 * sys_sync_file_range() permits finely controlled syncing over a segment of 252 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is 253 * zero then sys_sync_file_range() will operate from offset out to EOF. 254 * 255 * The flag bits are: 256 * 257 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range 258 * before performing the write. 259 * 260 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the 261 * range which are not presently under writeback. Note that this may block for 262 * significant periods due to exhaustion of disk request structures. 263 * 264 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range 265 * after performing the write. 266 * 267 * Useful combinations of the flag bits are: 268 * 269 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages 270 * in the range which were dirty on entry to sys_sync_file_range() are placed 271 * under writeout. This is a start-write-for-data-integrity operation. 272 * 273 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which 274 * are not presently under writeout. This is an asynchronous flush-to-disk 275 * operation. Not suitable for data integrity operations. 276 * 277 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for 278 * completion of writeout of all pages in the range. This will be used after an 279 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait 280 * for that operation to complete and to return the result. 281 * 282 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: 283 * a traditional sync() operation. This is a write-for-data-integrity operation 284 * which will ensure that all pages in the range which were dirty on entry to 285 * sys_sync_file_range() are committed to disk. 286 * 287 * 288 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any 289 * I/O errors or ENOSPC conditions and will return those to the caller, after 290 * clearing the EIO and ENOSPC flags in the address_space. 291 * 292 * It should be noted that none of these operations write out the file's 293 * metadata. So unless the application is strictly performing overwrites of 294 * already-instantiated disk blocks, there are no guarantees here that the data 295 * will be available after a crash. 296 */ 297 SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes, 298 unsigned int flags) 299 { 300 int ret; 301 struct file *file; 302 struct address_space *mapping; 303 loff_t endbyte; /* inclusive */ 304 int fput_needed; 305 umode_t i_mode; 306 307 ret = -EINVAL; 308 if (flags & ~VALID_FLAGS) 309 goto out; 310 311 endbyte = offset + nbytes; 312 313 if ((s64)offset < 0) 314 goto out; 315 if ((s64)endbyte < 0) 316 goto out; 317 if (endbyte < offset) 318 goto out; 319 320 if (sizeof(pgoff_t) == 4) { 321 if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 322 /* 323 * The range starts outside a 32 bit machine's 324 * pagecache addressing capabilities. Let it "succeed" 325 */ 326 ret = 0; 327 goto out; 328 } 329 if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 330 /* 331 * Out to EOF 332 */ 333 nbytes = 0; 334 } 335 } 336 337 if (nbytes == 0) 338 endbyte = LLONG_MAX; 339 else 340 endbyte--; /* inclusive */ 341 342 ret = -EBADF; 343 file = fget_light(fd, &fput_needed); 344 if (!file) 345 goto out; 346 347 i_mode = file->f_path.dentry->d_inode->i_mode; 348 ret = -ESPIPE; 349 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && 350 !S_ISLNK(i_mode)) 351 goto out_put; 352 353 mapping = file->f_mapping; 354 if (!mapping) { 355 ret = -EINVAL; 356 goto out_put; 357 } 358 359 ret = 0; 360 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { 361 ret = filemap_fdatawait_range(mapping, offset, endbyte); 362 if (ret < 0) 363 goto out_put; 364 } 365 366 if (flags & SYNC_FILE_RANGE_WRITE) { 367 ret = filemap_fdatawrite_range(mapping, offset, endbyte); 368 if (ret < 0) 369 goto out_put; 370 } 371 372 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) 373 ret = filemap_fdatawait_range(mapping, offset, endbyte); 374 375 out_put: 376 fput_light(file, fput_needed); 377 out: 378 return ret; 379 } 380 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS 381 asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes, 382 long flags) 383 { 384 return SYSC_sync_file_range((int) fd, offset, nbytes, 385 (unsigned int) flags); 386 } 387 SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range); 388 #endif 389 390 /* It would be nice if people remember that not all the world's an i386 391 when they introduce new system calls */ 392 SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags, 393 loff_t offset, loff_t nbytes) 394 { 395 return sys_sync_file_range(fd, offset, nbytes, flags); 396 } 397 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS 398 asmlinkage long SyS_sync_file_range2(long fd, long flags, 399 loff_t offset, loff_t nbytes) 400 { 401 return SYSC_sync_file_range2((int) fd, (unsigned int) flags, 402 offset, nbytes); 403 } 404 SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2); 405 #endif 406