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_iflags & SB_I_SKIP_SYNC) && 80 sb->s_op->sync_fs) 81 sb->s_op->sync_fs(sb, *(int *)arg); 82 } 83 84 static void fdatawrite_one_bdev(struct block_device *bdev, void *arg) 85 { 86 filemap_fdatawrite(bdev->bd_inode->i_mapping); 87 } 88 89 static void fdatawait_one_bdev(struct block_device *bdev, void *arg) 90 { 91 /* 92 * We keep the error status of individual mapping so that 93 * applications can catch the writeback error using fsync(2). 94 * See filemap_fdatawait_keep_errors() for details. 95 */ 96 filemap_fdatawait_keep_errors(bdev->bd_inode->i_mapping); 97 } 98 99 /* 100 * Sync everything. We start by waking flusher threads so that most of 101 * writeback runs on all devices in parallel. Then we sync all inodes reliably 102 * which effectively also waits for all flusher threads to finish doing 103 * writeback. At this point all data is on disk so metadata should be stable 104 * and we tell filesystems to sync their metadata via ->sync_fs() calls. 105 * Finally, we writeout all block devices because some filesystems (e.g. ext2) 106 * just write metadata (such as inodes or bitmaps) to block device page cache 107 * and do not sync it on their own in ->sync_fs(). 108 */ 109 void ksys_sync(void) 110 { 111 int nowait = 0, wait = 1; 112 113 wakeup_flusher_threads(WB_REASON_SYNC); 114 iterate_supers(sync_inodes_one_sb, NULL); 115 iterate_supers(sync_fs_one_sb, &nowait); 116 iterate_supers(sync_fs_one_sb, &wait); 117 iterate_bdevs(fdatawrite_one_bdev, NULL); 118 iterate_bdevs(fdatawait_one_bdev, NULL); 119 if (unlikely(laptop_mode)) 120 laptop_sync_completion(); 121 } 122 123 SYSCALL_DEFINE0(sync) 124 { 125 ksys_sync(); 126 return 0; 127 } 128 129 static void do_sync_work(struct work_struct *work) 130 { 131 int nowait = 0; 132 133 /* 134 * Sync twice to reduce the possibility we skipped some inodes / pages 135 * because they were temporarily locked 136 */ 137 iterate_supers(sync_inodes_one_sb, &nowait); 138 iterate_supers(sync_fs_one_sb, &nowait); 139 iterate_bdevs(fdatawrite_one_bdev, NULL); 140 iterate_supers(sync_inodes_one_sb, &nowait); 141 iterate_supers(sync_fs_one_sb, &nowait); 142 iterate_bdevs(fdatawrite_one_bdev, NULL); 143 printk("Emergency Sync complete\n"); 144 kfree(work); 145 } 146 147 void emergency_sync(void) 148 { 149 struct work_struct *work; 150 151 work = kmalloc(sizeof(*work), GFP_ATOMIC); 152 if (work) { 153 INIT_WORK(work, do_sync_work); 154 schedule_work(work); 155 } 156 } 157 158 /* 159 * sync a single super 160 */ 161 SYSCALL_DEFINE1(syncfs, int, fd) 162 { 163 struct fd f = fdget(fd); 164 struct super_block *sb; 165 int ret, ret2; 166 167 if (!f.file) 168 return -EBADF; 169 sb = f.file->f_path.dentry->d_sb; 170 171 down_read(&sb->s_umount); 172 ret = sync_filesystem(sb); 173 up_read(&sb->s_umount); 174 175 ret2 = errseq_check_and_advance(&sb->s_wb_err, &f.file->f_sb_err); 176 177 fdput(f); 178 return ret ? ret : ret2; 179 } 180 181 /** 182 * vfs_fsync_range - helper to sync a range of data & metadata to disk 183 * @file: file to sync 184 * @start: offset in bytes of the beginning of data range to sync 185 * @end: offset in bytes of the end of data range (inclusive) 186 * @datasync: perform only datasync 187 * 188 * Write back data in range @start..@end and metadata for @file to disk. If 189 * @datasync is set only metadata needed to access modified file data is 190 * written. 191 */ 192 int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) 193 { 194 struct inode *inode = file->f_mapping->host; 195 196 if (!file->f_op->fsync) 197 return -EINVAL; 198 if (!datasync && (inode->i_state & I_DIRTY_TIME)) 199 mark_inode_dirty_sync(inode); 200 return file->f_op->fsync(file, start, end, datasync); 201 } 202 EXPORT_SYMBOL(vfs_fsync_range); 203 204 /** 205 * vfs_fsync - perform a fsync or fdatasync on a file 206 * @file: file to sync 207 * @datasync: only perform a fdatasync operation 208 * 209 * Write back data and metadata for @file to disk. If @datasync is 210 * set only metadata needed to access modified file data is written. 211 */ 212 int vfs_fsync(struct file *file, int datasync) 213 { 214 return vfs_fsync_range(file, 0, LLONG_MAX, datasync); 215 } 216 EXPORT_SYMBOL(vfs_fsync); 217 218 static int do_fsync(unsigned int fd, int datasync) 219 { 220 struct fd f = fdget(fd); 221 int ret = -EBADF; 222 223 if (f.file) { 224 ret = vfs_fsync(f.file, datasync); 225 fdput(f); 226 } 227 return ret; 228 } 229 230 SYSCALL_DEFINE1(fsync, unsigned int, fd) 231 { 232 return do_fsync(fd, 0); 233 } 234 235 SYSCALL_DEFINE1(fdatasync, unsigned int, fd) 236 { 237 return do_fsync(fd, 1); 238 } 239 240 int sync_file_range(struct file *file, loff_t offset, loff_t nbytes, 241 unsigned int flags) 242 { 243 int ret; 244 struct address_space *mapping; 245 loff_t endbyte; /* inclusive */ 246 umode_t i_mode; 247 248 ret = -EINVAL; 249 if (flags & ~VALID_FLAGS) 250 goto out; 251 252 endbyte = offset + nbytes; 253 254 if ((s64)offset < 0) 255 goto out; 256 if ((s64)endbyte < 0) 257 goto out; 258 if (endbyte < offset) 259 goto out; 260 261 if (sizeof(pgoff_t) == 4) { 262 if (offset >= (0x100000000ULL << PAGE_SHIFT)) { 263 /* 264 * The range starts outside a 32 bit machine's 265 * pagecache addressing capabilities. Let it "succeed" 266 */ 267 ret = 0; 268 goto out; 269 } 270 if (endbyte >= (0x100000000ULL << PAGE_SHIFT)) { 271 /* 272 * Out to EOF 273 */ 274 nbytes = 0; 275 } 276 } 277 278 if (nbytes == 0) 279 endbyte = LLONG_MAX; 280 else 281 endbyte--; /* inclusive */ 282 283 i_mode = file_inode(file)->i_mode; 284 ret = -ESPIPE; 285 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && 286 !S_ISLNK(i_mode)) 287 goto out; 288 289 mapping = file->f_mapping; 290 ret = 0; 291 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { 292 ret = file_fdatawait_range(file, offset, endbyte); 293 if (ret < 0) 294 goto out; 295 } 296 297 if (flags & SYNC_FILE_RANGE_WRITE) { 298 int sync_mode = WB_SYNC_NONE; 299 300 if ((flags & SYNC_FILE_RANGE_WRITE_AND_WAIT) == 301 SYNC_FILE_RANGE_WRITE_AND_WAIT) 302 sync_mode = WB_SYNC_ALL; 303 304 ret = __filemap_fdatawrite_range(mapping, offset, endbyte, 305 sync_mode); 306 if (ret < 0) 307 goto out; 308 } 309 310 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) 311 ret = file_fdatawait_range(file, offset, endbyte); 312 313 out: 314 return ret; 315 } 316 317 /* 318 * ksys_sync_file_range() permits finely controlled syncing over a segment of 319 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is 320 * zero then ksys_sync_file_range() will operate from offset out to EOF. 321 * 322 * The flag bits are: 323 * 324 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range 325 * before performing the write. 326 * 327 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the 328 * range which are not presently under writeback. Note that this may block for 329 * significant periods due to exhaustion of disk request structures. 330 * 331 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range 332 * after performing the write. 333 * 334 * Useful combinations of the flag bits are: 335 * 336 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages 337 * in the range which were dirty on entry to ksys_sync_file_range() are placed 338 * under writeout. This is a start-write-for-data-integrity operation. 339 * 340 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which 341 * are not presently under writeout. This is an asynchronous flush-to-disk 342 * operation. Not suitable for data integrity operations. 343 * 344 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for 345 * completion of writeout of all pages in the range. This will be used after an 346 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait 347 * for that operation to complete and to return the result. 348 * 349 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER 350 * (a.k.a. SYNC_FILE_RANGE_WRITE_AND_WAIT): 351 * a traditional sync() operation. This is a write-for-data-integrity operation 352 * which will ensure that all pages in the range which were dirty on entry to 353 * ksys_sync_file_range() are written to disk. It should be noted that disk 354 * caches are not flushed by this call, so there are no guarantees here that the 355 * data will be available on disk after a crash. 356 * 357 * 358 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any 359 * I/O errors or ENOSPC conditions and will return those to the caller, after 360 * clearing the EIO and ENOSPC flags in the address_space. 361 * 362 * It should be noted that none of these operations write out the file's 363 * metadata. So unless the application is strictly performing overwrites of 364 * already-instantiated disk blocks, there are no guarantees here that the data 365 * will be available after a crash. 366 */ 367 int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes, 368 unsigned int flags) 369 { 370 int ret; 371 struct fd f; 372 373 ret = -EBADF; 374 f = fdget(fd); 375 if (f.file) 376 ret = sync_file_range(f.file, offset, nbytes, flags); 377 378 fdput(f); 379 return ret; 380 } 381 382 SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes, 383 unsigned int, flags) 384 { 385 return ksys_sync_file_range(fd, offset, nbytes, flags); 386 } 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_DEFINE4(sync_file_range2, int, fd, unsigned int, flags, 391 loff_t, offset, loff_t, nbytes) 392 { 393 return ksys_sync_file_range(fd, offset, nbytes, flags); 394 } 395