1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * High-level sync()-related operations 4 */ 5 6 #include <linux/kernel.h> 7 #include <linux/file.h> 8 #include <linux/fs.h> 9 #include <linux/slab.h> 10 #include <linux/export.h> 11 #include <linux/namei.h> 12 #include <linux/sched.h> 13 #include <linux/writeback.h> 14 #include <linux/syscalls.h> 15 #include <linux/linkage.h> 16 #include <linux/pagemap.h> 17 #include <linux/quotaops.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 if (wait) 34 sync_inodes_sb(sb); 35 else 36 writeback_inodes_sb(sb, WB_REASON_SYNC); 37 38 if (sb->s_op->sync_fs) 39 sb->s_op->sync_fs(sb, wait); 40 return __sync_blockdev(sb->s_bdev, wait); 41 } 42 43 /* 44 * Write out and wait upon all dirty data associated with this 45 * superblock. Filesystem data as well as the underlying block 46 * device. Takes the superblock lock. 47 */ 48 int sync_filesystem(struct super_block *sb) 49 { 50 int ret; 51 52 /* 53 * We need to be protected against the filesystem going from 54 * r/o to r/w or vice versa. 55 */ 56 WARN_ON(!rwsem_is_locked(&sb->s_umount)); 57 58 /* 59 * No point in syncing out anything if the filesystem is read-only. 60 */ 61 if (sb_rdonly(sb)) 62 return 0; 63 64 ret = __sync_filesystem(sb, 0); 65 if (ret < 0) 66 return ret; 67 return __sync_filesystem(sb, 1); 68 } 69 EXPORT_SYMBOL(sync_filesystem); 70 71 static void sync_inodes_one_sb(struct super_block *sb, void *arg) 72 { 73 if (!sb_rdonly(sb)) 74 sync_inodes_sb(sb); 75 } 76 77 static void sync_fs_one_sb(struct super_block *sb, void *arg) 78 { 79 if (!sb_rdonly(sb) && sb->s_op->sync_fs) 80 sb->s_op->sync_fs(sb, *(int *)arg); 81 } 82 83 static void fdatawrite_one_bdev(struct block_device *bdev, void *arg) 84 { 85 filemap_fdatawrite(bdev->bd_inode->i_mapping); 86 } 87 88 static void fdatawait_one_bdev(struct block_device *bdev, void *arg) 89 { 90 /* 91 * We keep the error status of individual mapping so that 92 * applications can catch the writeback error using fsync(2). 93 * See filemap_fdatawait_keep_errors() for details. 94 */ 95 filemap_fdatawait_keep_errors(bdev->bd_inode->i_mapping); 96 } 97 98 /* 99 * Sync everything. We start by waking flusher threads so that most of 100 * writeback runs on all devices in parallel. Then we sync all inodes reliably 101 * which effectively also waits for all flusher threads to finish doing 102 * writeback. At this point all data is on disk so metadata should be stable 103 * and we tell filesystems to sync their metadata via ->sync_fs() calls. 104 * Finally, we writeout all block devices because some filesystems (e.g. ext2) 105 * just write metadata (such as inodes or bitmaps) to block device page cache 106 * and do not sync it on their own in ->sync_fs(). 107 */ 108 void ksys_sync(void) 109 { 110 int nowait = 0, wait = 1; 111 112 wakeup_flusher_threads(WB_REASON_SYNC); 113 iterate_supers(sync_inodes_one_sb, NULL); 114 iterate_supers(sync_fs_one_sb, &nowait); 115 iterate_supers(sync_fs_one_sb, &wait); 116 iterate_bdevs(fdatawrite_one_bdev, NULL); 117 iterate_bdevs(fdatawait_one_bdev, NULL); 118 if (unlikely(laptop_mode)) 119 laptop_sync_completion(); 120 } 121 122 SYSCALL_DEFINE0(sync) 123 { 124 ksys_sync(); 125 return 0; 126 } 127 128 static void do_sync_work(struct work_struct *work) 129 { 130 int nowait = 0; 131 132 /* 133 * Sync twice to reduce the possibility we skipped some inodes / pages 134 * because they were temporarily locked 135 */ 136 iterate_supers(sync_inodes_one_sb, &nowait); 137 iterate_supers(sync_fs_one_sb, &nowait); 138 iterate_bdevs(fdatawrite_one_bdev, NULL); 139 iterate_supers(sync_inodes_one_sb, &nowait); 140 iterate_supers(sync_fs_one_sb, &nowait); 141 iterate_bdevs(fdatawrite_one_bdev, NULL); 142 printk("Emergency Sync complete\n"); 143 kfree(work); 144 } 145 146 void emergency_sync(void) 147 { 148 struct work_struct *work; 149 150 work = kmalloc(sizeof(*work), GFP_ATOMIC); 151 if (work) { 152 INIT_WORK(work, do_sync_work); 153 schedule_work(work); 154 } 155 } 156 157 /* 158 * sync a single super 159 */ 160 SYSCALL_DEFINE1(syncfs, int, fd) 161 { 162 struct fd f = fdget(fd); 163 struct super_block *sb; 164 int ret; 165 166 if (!f.file) 167 return -EBADF; 168 sb = f.file->f_path.dentry->d_sb; 169 170 down_read(&sb->s_umount); 171 ret = sync_filesystem(sb); 172 up_read(&sb->s_umount); 173 174 fdput(f); 175 return ret; 176 } 177 178 /** 179 * vfs_fsync_range - helper to sync a range of data & metadata to disk 180 * @file: file to sync 181 * @start: offset in bytes of the beginning of data range to sync 182 * @end: offset in bytes of the end of data range (inclusive) 183 * @datasync: perform only datasync 184 * 185 * Write back data in range @start..@end and metadata for @file to disk. If 186 * @datasync is set only metadata needed to access modified file data is 187 * written. 188 */ 189 int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) 190 { 191 struct inode *inode = file->f_mapping->host; 192 193 if (!file->f_op->fsync) 194 return -EINVAL; 195 if (!datasync && (inode->i_state & I_DIRTY_TIME)) 196 mark_inode_dirty_sync(inode); 197 return file->f_op->fsync(file, start, end, datasync); 198 } 199 EXPORT_SYMBOL(vfs_fsync_range); 200 201 /** 202 * vfs_fsync - perform a fsync or fdatasync on a file 203 * @file: file to sync 204 * @datasync: only perform a fdatasync operation 205 * 206 * Write back data and metadata for @file to disk. If @datasync is 207 * set only metadata needed to access modified file data is written. 208 */ 209 int vfs_fsync(struct file *file, int datasync) 210 { 211 return vfs_fsync_range(file, 0, LLONG_MAX, datasync); 212 } 213 EXPORT_SYMBOL(vfs_fsync); 214 215 static int do_fsync(unsigned int fd, int datasync) 216 { 217 struct fd f = fdget(fd); 218 int ret = -EBADF; 219 220 if (f.file) { 221 ret = vfs_fsync(f.file, datasync); 222 fdput(f); 223 } 224 return ret; 225 } 226 227 SYSCALL_DEFINE1(fsync, unsigned int, fd) 228 { 229 return do_fsync(fd, 0); 230 } 231 232 SYSCALL_DEFINE1(fdatasync, unsigned int, fd) 233 { 234 return do_fsync(fd, 1); 235 } 236 237 int sync_file_range(struct file *file, loff_t offset, loff_t nbytes, 238 unsigned int flags) 239 { 240 int ret; 241 struct address_space *mapping; 242 loff_t endbyte; /* inclusive */ 243 umode_t i_mode; 244 245 ret = -EINVAL; 246 if (flags & ~VALID_FLAGS) 247 goto out; 248 249 endbyte = offset + nbytes; 250 251 if ((s64)offset < 0) 252 goto out; 253 if ((s64)endbyte < 0) 254 goto out; 255 if (endbyte < offset) 256 goto out; 257 258 if (sizeof(pgoff_t) == 4) { 259 if (offset >= (0x100000000ULL << PAGE_SHIFT)) { 260 /* 261 * The range starts outside a 32 bit machine's 262 * pagecache addressing capabilities. Let it "succeed" 263 */ 264 ret = 0; 265 goto out; 266 } 267 if (endbyte >= (0x100000000ULL << PAGE_SHIFT)) { 268 /* 269 * Out to EOF 270 */ 271 nbytes = 0; 272 } 273 } 274 275 if (nbytes == 0) 276 endbyte = LLONG_MAX; 277 else 278 endbyte--; /* inclusive */ 279 280 i_mode = file_inode(file)->i_mode; 281 ret = -ESPIPE; 282 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && 283 !S_ISLNK(i_mode)) 284 goto out; 285 286 mapping = file->f_mapping; 287 ret = 0; 288 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { 289 ret = file_fdatawait_range(file, offset, endbyte); 290 if (ret < 0) 291 goto out; 292 } 293 294 if (flags & SYNC_FILE_RANGE_WRITE) { 295 int sync_mode = WB_SYNC_NONE; 296 297 if ((flags & SYNC_FILE_RANGE_WRITE_AND_WAIT) == 298 SYNC_FILE_RANGE_WRITE_AND_WAIT) 299 sync_mode = WB_SYNC_ALL; 300 301 ret = __filemap_fdatawrite_range(mapping, offset, endbyte, 302 sync_mode); 303 if (ret < 0) 304 goto out; 305 } 306 307 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) 308 ret = file_fdatawait_range(file, offset, endbyte); 309 310 out: 311 return ret; 312 } 313 314 /* 315 * ksys_sync_file_range() permits finely controlled syncing over a segment of 316 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is 317 * zero then ksys_sync_file_range() will operate from offset out to EOF. 318 * 319 * The flag bits are: 320 * 321 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range 322 * before performing the write. 323 * 324 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the 325 * range which are not presently under writeback. Note that this may block for 326 * significant periods due to exhaustion of disk request structures. 327 * 328 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range 329 * after performing the write. 330 * 331 * Useful combinations of the flag bits are: 332 * 333 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages 334 * in the range which were dirty on entry to ksys_sync_file_range() are placed 335 * under writeout. This is a start-write-for-data-integrity operation. 336 * 337 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which 338 * are not presently under writeout. This is an asynchronous flush-to-disk 339 * operation. Not suitable for data integrity operations. 340 * 341 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for 342 * completion of writeout of all pages in the range. This will be used after an 343 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait 344 * for that operation to complete and to return the result. 345 * 346 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER 347 * (a.k.a. SYNC_FILE_RANGE_WRITE_AND_WAIT): 348 * a traditional sync() operation. This is a write-for-data-integrity operation 349 * which will ensure that all pages in the range which were dirty on entry to 350 * ksys_sync_file_range() are written to disk. It should be noted that disk 351 * caches are not flushed by this call, so there are no guarantees here that the 352 * data will be available on disk after a crash. 353 * 354 * 355 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any 356 * I/O errors or ENOSPC conditions and will return those to the caller, after 357 * clearing the EIO and ENOSPC flags in the address_space. 358 * 359 * It should be noted that none of these operations write out the file's 360 * metadata. So unless the application is strictly performing overwrites of 361 * already-instantiated disk blocks, there are no guarantees here that the data 362 * will be available after a crash. 363 */ 364 int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes, 365 unsigned int flags) 366 { 367 int ret; 368 struct fd f; 369 370 ret = -EBADF; 371 f = fdget(fd); 372 if (f.file) 373 ret = sync_file_range(f.file, offset, nbytes, flags); 374 375 fdput(f); 376 return ret; 377 } 378 379 SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes, 380 unsigned int, flags) 381 { 382 return ksys_sync_file_range(fd, offset, nbytes, flags); 383 } 384 385 /* It would be nice if people remember that not all the world's an i386 386 when they introduce new system calls */ 387 SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags, 388 loff_t, offset, loff_t, nbytes) 389 { 390 return ksys_sync_file_range(fd, offset, nbytes, flags); 391 } 392