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/module.h> 9 #include <linux/sched.h> 10 #include <linux/writeback.h> 11 #include <linux/syscalls.h> 12 #include <linux/linkage.h> 13 #include <linux/pagemap.h> 14 #include <linux/quotaops.h> 15 #include <linux/buffer_head.h> 16 #include "internal.h" 17 18 #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \ 19 SYNC_FILE_RANGE_WAIT_AFTER) 20 21 /* 22 * Do the filesystem syncing work. For simple filesystems sync_inodes_sb(sb, 0) 23 * just dirties buffers with inodes so we have to submit IO for these buffers 24 * via __sync_blockdev(). This also speeds up the wait == 1 case since in that 25 * case write_inode() functions do sync_dirty_buffer() and thus effectively 26 * write one block at a time. 27 */ 28 static int __sync_filesystem(struct super_block *sb, int wait) 29 { 30 /* Avoid doing twice syncing and cache pruning for quota sync */ 31 if (!wait) 32 writeout_quota_sb(sb, -1); 33 else 34 sync_quota_sb(sb, -1); 35 sync_inodes_sb(sb, wait); 36 if (sb->s_op->sync_fs) 37 sb->s_op->sync_fs(sb, wait); 38 return __sync_blockdev(sb->s_bdev, wait); 39 } 40 41 /* 42 * Write out and wait upon all dirty data associated with this 43 * superblock. Filesystem data as well as the underlying block 44 * device. Takes the superblock lock. 45 */ 46 int sync_filesystem(struct super_block *sb) 47 { 48 int ret; 49 50 /* 51 * We need to be protected against the filesystem going from 52 * r/o to r/w or vice versa. 53 */ 54 WARN_ON(!rwsem_is_locked(&sb->s_umount)); 55 56 /* 57 * No point in syncing out anything if the filesystem is read-only. 58 */ 59 if (sb->s_flags & MS_RDONLY) 60 return 0; 61 62 ret = __sync_filesystem(sb, 0); 63 if (ret < 0) 64 return ret; 65 return __sync_filesystem(sb, 1); 66 } 67 EXPORT_SYMBOL_GPL(sync_filesystem); 68 69 /* 70 * Sync all the data for all the filesystems (called by sys_sync() and 71 * emergency sync) 72 * 73 * This operation is careful to avoid the livelock which could easily happen 74 * if two or more filesystems are being continuously dirtied. s_need_sync 75 * is used only here. We set it against all filesystems and then clear it as 76 * we sync them. So redirtied filesystems are skipped. 77 * 78 * But if process A is currently running sync_filesystems and then process B 79 * calls sync_filesystems as well, process B will set all the s_need_sync 80 * flags again, which will cause process A to resync everything. Fix that with 81 * a local mutex. 82 */ 83 static void sync_filesystems(int wait) 84 { 85 struct super_block *sb; 86 static DEFINE_MUTEX(mutex); 87 88 mutex_lock(&mutex); /* Could be down_interruptible */ 89 spin_lock(&sb_lock); 90 list_for_each_entry(sb, &super_blocks, s_list) 91 sb->s_need_sync = 1; 92 93 restart: 94 list_for_each_entry(sb, &super_blocks, s_list) { 95 if (!sb->s_need_sync) 96 continue; 97 sb->s_need_sync = 0; 98 sb->s_count++; 99 spin_unlock(&sb_lock); 100 101 down_read(&sb->s_umount); 102 if (!(sb->s_flags & MS_RDONLY) && sb->s_root) 103 __sync_filesystem(sb, wait); 104 up_read(&sb->s_umount); 105 106 /* restart only when sb is no longer on the list */ 107 spin_lock(&sb_lock); 108 if (__put_super_and_need_restart(sb)) 109 goto restart; 110 } 111 spin_unlock(&sb_lock); 112 mutex_unlock(&mutex); 113 } 114 115 SYSCALL_DEFINE0(sync) 116 { 117 sync_filesystems(0); 118 sync_filesystems(1); 119 if (unlikely(laptop_mode)) 120 laptop_sync_completion(); 121 return 0; 122 } 123 124 static void do_sync_work(struct work_struct *work) 125 { 126 /* 127 * Sync twice to reduce the possibility we skipped some inodes / pages 128 * because they were temporarily locked 129 */ 130 sync_filesystems(0); 131 sync_filesystems(0); 132 printk("Emergency Sync complete\n"); 133 kfree(work); 134 } 135 136 void emergency_sync(void) 137 { 138 struct work_struct *work; 139 140 work = kmalloc(sizeof(*work), GFP_ATOMIC); 141 if (work) { 142 INIT_WORK(work, do_sync_work); 143 schedule_work(work); 144 } 145 } 146 147 /* 148 * Generic function to fsync a file. 149 * 150 * filp may be NULL if called via the msync of a vma. 151 */ 152 int file_fsync(struct file *filp, struct dentry *dentry, int datasync) 153 { 154 struct inode * inode = dentry->d_inode; 155 struct super_block * sb; 156 int ret, err; 157 158 /* sync the inode to buffers */ 159 ret = write_inode_now(inode, 0); 160 161 /* sync the superblock to buffers */ 162 sb = inode->i_sb; 163 if (sb->s_dirt && sb->s_op->write_super) 164 sb->s_op->write_super(sb); 165 166 /* .. finally sync the buffers to disk */ 167 err = sync_blockdev(sb->s_bdev); 168 if (!ret) 169 ret = err; 170 return ret; 171 } 172 173 /** 174 * vfs_fsync - perform a fsync or fdatasync on a file 175 * @file: file to sync 176 * @dentry: dentry of @file 177 * @data: only perform a fdatasync operation 178 * 179 * Write back data and metadata for @file to disk. If @datasync is 180 * set only metadata needed to access modified file data is written. 181 * 182 * In case this function is called from nfsd @file may be %NULL and 183 * only @dentry is set. This can only happen when the filesystem 184 * implements the export_operations API. 185 */ 186 int vfs_fsync(struct file *file, struct dentry *dentry, int datasync) 187 { 188 const struct file_operations *fop; 189 struct address_space *mapping; 190 int err, ret; 191 192 /* 193 * Get mapping and operations from the file in case we have 194 * as file, or get the default values for them in case we 195 * don't have a struct file available. Damn nfsd.. 196 */ 197 if (file) { 198 mapping = file->f_mapping; 199 fop = file->f_op; 200 } else { 201 mapping = dentry->d_inode->i_mapping; 202 fop = dentry->d_inode->i_fop; 203 } 204 205 if (!fop || !fop->fsync) { 206 ret = -EINVAL; 207 goto out; 208 } 209 210 ret = filemap_fdatawrite(mapping); 211 212 /* 213 * We need to protect against concurrent writers, which could cause 214 * livelocks in fsync_buffers_list(). 215 */ 216 mutex_lock(&mapping->host->i_mutex); 217 err = fop->fsync(file, dentry, datasync); 218 if (!ret) 219 ret = err; 220 mutex_unlock(&mapping->host->i_mutex); 221 err = filemap_fdatawait(mapping); 222 if (!ret) 223 ret = err; 224 out: 225 return ret; 226 } 227 EXPORT_SYMBOL(vfs_fsync); 228 229 static int do_fsync(unsigned int fd, int datasync) 230 { 231 struct file *file; 232 int ret = -EBADF; 233 234 file = fget(fd); 235 if (file) { 236 ret = vfs_fsync(file, file->f_path.dentry, datasync); 237 fput(file); 238 } 239 return ret; 240 } 241 242 SYSCALL_DEFINE1(fsync, unsigned int, fd) 243 { 244 return do_fsync(fd, 0); 245 } 246 247 SYSCALL_DEFINE1(fdatasync, unsigned int, fd) 248 { 249 return do_fsync(fd, 1); 250 } 251 252 /* 253 * sys_sync_file_range() permits finely controlled syncing over a segment of 254 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is 255 * zero then sys_sync_file_range() will operate from offset out to EOF. 256 * 257 * The flag bits are: 258 * 259 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range 260 * before performing the write. 261 * 262 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the 263 * range which are not presently under writeback. Note that this may block for 264 * significant periods due to exhaustion of disk request structures. 265 * 266 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range 267 * after performing the write. 268 * 269 * Useful combinations of the flag bits are: 270 * 271 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages 272 * in the range which were dirty on entry to sys_sync_file_range() are placed 273 * under writeout. This is a start-write-for-data-integrity operation. 274 * 275 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which 276 * are not presently under writeout. This is an asynchronous flush-to-disk 277 * operation. Not suitable for data integrity operations. 278 * 279 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for 280 * completion of writeout of all pages in the range. This will be used after an 281 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait 282 * for that operation to complete and to return the result. 283 * 284 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: 285 * a traditional sync() operation. This is a write-for-data-integrity operation 286 * which will ensure that all pages in the range which were dirty on entry to 287 * sys_sync_file_range() are committed to disk. 288 * 289 * 290 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any 291 * I/O errors or ENOSPC conditions and will return those to the caller, after 292 * clearing the EIO and ENOSPC flags in the address_space. 293 * 294 * It should be noted that none of these operations write out the file's 295 * metadata. So unless the application is strictly performing overwrites of 296 * already-instantiated disk blocks, there are no guarantees here that the data 297 * will be available after a crash. 298 */ 299 SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes, 300 unsigned int flags) 301 { 302 int ret; 303 struct file *file; 304 loff_t endbyte; /* inclusive */ 305 int fput_needed; 306 umode_t i_mode; 307 308 ret = -EINVAL; 309 if (flags & ~VALID_FLAGS) 310 goto out; 311 312 endbyte = offset + nbytes; 313 314 if ((s64)offset < 0) 315 goto out; 316 if ((s64)endbyte < 0) 317 goto out; 318 if (endbyte < offset) 319 goto out; 320 321 if (sizeof(pgoff_t) == 4) { 322 if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 323 /* 324 * The range starts outside a 32 bit machine's 325 * pagecache addressing capabilities. Let it "succeed" 326 */ 327 ret = 0; 328 goto out; 329 } 330 if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { 331 /* 332 * Out to EOF 333 */ 334 nbytes = 0; 335 } 336 } 337 338 if (nbytes == 0) 339 endbyte = LLONG_MAX; 340 else 341 endbyte--; /* inclusive */ 342 343 ret = -EBADF; 344 file = fget_light(fd, &fput_needed); 345 if (!file) 346 goto out; 347 348 i_mode = file->f_path.dentry->d_inode->i_mode; 349 ret = -ESPIPE; 350 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && 351 !S_ISLNK(i_mode)) 352 goto out_put; 353 354 ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags); 355 out_put: 356 fput_light(file, fput_needed); 357 out: 358 return ret; 359 } 360 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS 361 asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes, 362 long flags) 363 { 364 return SYSC_sync_file_range((int) fd, offset, nbytes, 365 (unsigned int) flags); 366 } 367 SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range); 368 #endif 369 370 /* It would be nice if people remember that not all the world's an i386 371 when they introduce new system calls */ 372 SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags, 373 loff_t offset, loff_t nbytes) 374 { 375 return sys_sync_file_range(fd, offset, nbytes, flags); 376 } 377 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS 378 asmlinkage long SyS_sync_file_range2(long fd, long flags, 379 loff_t offset, loff_t nbytes) 380 { 381 return SYSC_sync_file_range2((int) fd, (unsigned int) flags, 382 offset, nbytes); 383 } 384 SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2); 385 #endif 386 387 /* 388 * `endbyte' is inclusive 389 */ 390 int do_sync_mapping_range(struct address_space *mapping, loff_t offset, 391 loff_t endbyte, unsigned int flags) 392 { 393 int ret; 394 395 if (!mapping) { 396 ret = -EINVAL; 397 goto out; 398 } 399 400 ret = 0; 401 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { 402 ret = wait_on_page_writeback_range(mapping, 403 offset >> PAGE_CACHE_SHIFT, 404 endbyte >> PAGE_CACHE_SHIFT); 405 if (ret < 0) 406 goto out; 407 } 408 409 if (flags & SYNC_FILE_RANGE_WRITE) { 410 ret = __filemap_fdatawrite_range(mapping, offset, endbyte, 411 WB_SYNC_ALL); 412 if (ret < 0) 413 goto out; 414 } 415 416 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) { 417 ret = wait_on_page_writeback_range(mapping, 418 offset >> PAGE_CACHE_SHIFT, 419 endbyte >> PAGE_CACHE_SHIFT); 420 } 421 out: 422 return ret; 423 } 424 EXPORT_SYMBOL_GPL(do_sync_mapping_range); 425