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 * vfs_fsync_range - helper to sync a range of data & metadata to disk 133 * @file: file to sync 134 * @start: offset in bytes of the beginning of data range to sync 135 * @end: offset in bytes of the end of data range (inclusive) 136 * @datasync: perform only datasync 137 * 138 * Write back data in range @start..@end and metadata for @file to disk. If 139 * @datasync is set only metadata needed to access modified file data is 140 * written. 141 */ 142 int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) 143 { 144 struct address_space *mapping = file->f_mapping; 145 int err, ret; 146 147 if (!file->f_op || !file->f_op->fsync) { 148 ret = -EINVAL; 149 goto out; 150 } 151 152 ret = filemap_write_and_wait_range(mapping, start, end); 153 154 /* 155 * We need to protect against concurrent writers, which could cause 156 * livelocks in fsync_buffers_list(). 157 */ 158 mutex_lock(&mapping->host->i_mutex); 159 err = file->f_op->fsync(file, datasync); 160 if (!ret) 161 ret = err; 162 mutex_unlock(&mapping->host->i_mutex); 163 164 out: 165 return ret; 166 } 167 EXPORT_SYMBOL(vfs_fsync_range); 168 169 /** 170 * vfs_fsync - perform a fsync or fdatasync on a file 171 * @file: file to sync 172 * @datasync: only perform a fdatasync operation 173 * 174 * Write back data and metadata for @file to disk. If @datasync is 175 * set only metadata needed to access modified file data is written. 176 */ 177 int vfs_fsync(struct file *file, int datasync) 178 { 179 return vfs_fsync_range(file, 0, LLONG_MAX, datasync); 180 } 181 EXPORT_SYMBOL(vfs_fsync); 182 183 static int do_fsync(unsigned int fd, int datasync) 184 { 185 struct file *file; 186 int ret = -EBADF; 187 188 file = fget(fd); 189 if (file) { 190 ret = vfs_fsync(file, datasync); 191 fput(file); 192 } 193 return ret; 194 } 195 196 SYSCALL_DEFINE1(fsync, unsigned int, fd) 197 { 198 return do_fsync(fd, 0); 199 } 200 201 SYSCALL_DEFINE1(fdatasync, unsigned int, fd) 202 { 203 return do_fsync(fd, 1); 204 } 205 206 /** 207 * generic_write_sync - perform syncing after a write if file / inode is sync 208 * @file: file to which the write happened 209 * @pos: offset where the write started 210 * @count: length of the write 211 * 212 * This is just a simple wrapper about our general syncing function. 213 */ 214 int generic_write_sync(struct file *file, loff_t pos, loff_t count) 215 { 216 if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host)) 217 return 0; 218 return vfs_fsync_range(file, pos, pos + count - 1, 219 (file->f_flags & __O_SYNC) ? 0 : 1); 220 } 221 EXPORT_SYMBOL(generic_write_sync); 222 223 /* 224 * sys_sync_file_range() permits finely controlled syncing over a segment of 225 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is 226 * zero then sys_sync_file_range() will operate from offset out to EOF. 227 * 228 * The flag bits are: 229 * 230 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range 231 * before performing the write. 232 * 233 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the 234 * range which are not presently under writeback. Note that this may block for 235 * significant periods due to exhaustion of disk request structures. 236 * 237 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range 238 * after performing the write. 239 * 240 * Useful combinations of the flag bits are: 241 * 242 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages 243 * in the range which were dirty on entry to sys_sync_file_range() are placed 244 * under writeout. This is a start-write-for-data-integrity operation. 245 * 246 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which 247 * are not presently under writeout. This is an asynchronous flush-to-disk 248 * operation. Not suitable for data integrity operations. 249 * 250 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for 251 * completion of writeout of all pages in the range. This will be used after an 252 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait 253 * for that operation to complete and to return the result. 254 * 255 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: 256 * a traditional sync() operation. This is a write-for-data-integrity operation 257 * which will ensure that all pages in the range which were dirty on entry to 258 * sys_sync_file_range() are committed to disk. 259 * 260 * 261 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any 262 * I/O errors or ENOSPC conditions and will return those to the caller, after 263 * clearing the EIO and ENOSPC flags in the address_space. 264 * 265 * It should be noted that none of these operations write out the file's 266 * metadata. So unless the application is strictly performing overwrites of 267 * already-instantiated disk blocks, there are no guarantees here that the data 268 * will be available after a crash. 269 */ 270 SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes, 271 unsigned int flags) 272 { 273 int ret; 274 struct file *file; 275 struct address_space *mapping; 276 loff_t endbyte; /* inclusive */ 277 int fput_needed; 278 umode_t i_mode; 279 280 ret = -EINVAL; 281 if (flags & ~VALID_FLAGS) 282 goto out; 283 284 endbyte = offset + nbytes; 285 286 if ((s64)offset < 0) 287 goto out; 288 if ((s64)endbyte < 0) 289 goto out; 290 if (endbyte < offset) 291 goto out; 292 293 if (sizeof(pgoff_t) == 4) { 294 if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 295 /* 296 * The range starts outside a 32 bit machine's 297 * pagecache addressing capabilities. Let it "succeed" 298 */ 299 ret = 0; 300 goto out; 301 } 302 if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 303 /* 304 * Out to EOF 305 */ 306 nbytes = 0; 307 } 308 } 309 310 if (nbytes == 0) 311 endbyte = LLONG_MAX; 312 else 313 endbyte--; /* inclusive */ 314 315 ret = -EBADF; 316 file = fget_light(fd, &fput_needed); 317 if (!file) 318 goto out; 319 320 i_mode = file->f_path.dentry->d_inode->i_mode; 321 ret = -ESPIPE; 322 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && 323 !S_ISLNK(i_mode)) 324 goto out_put; 325 326 mapping = file->f_mapping; 327 if (!mapping) { 328 ret = -EINVAL; 329 goto out_put; 330 } 331 332 ret = 0; 333 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { 334 ret = filemap_fdatawait_range(mapping, offset, endbyte); 335 if (ret < 0) 336 goto out_put; 337 } 338 339 if (flags & SYNC_FILE_RANGE_WRITE) { 340 ret = filemap_fdatawrite_range(mapping, offset, endbyte); 341 if (ret < 0) 342 goto out_put; 343 } 344 345 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) 346 ret = filemap_fdatawait_range(mapping, offset, endbyte); 347 348 out_put: 349 fput_light(file, fput_needed); 350 out: 351 return ret; 352 } 353 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS 354 asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes, 355 long flags) 356 { 357 return SYSC_sync_file_range((int) fd, offset, nbytes, 358 (unsigned int) flags); 359 } 360 SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range); 361 #endif 362 363 /* It would be nice if people remember that not all the world's an i386 364 when they introduce new system calls */ 365 SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags, 366 loff_t offset, loff_t nbytes) 367 { 368 return sys_sync_file_range(fd, offset, nbytes, flags); 369 } 370 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS 371 asmlinkage long SyS_sync_file_range2(long fd, long flags, 372 loff_t offset, loff_t nbytes) 373 { 374 return SYSC_sync_file_range2((int) fd, (unsigned int) flags, 375 offset, nbytes); 376 } 377 SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2); 378 #endif 379