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 spin_lock(&inode->i_lock); 197 inode->i_state &= ~I_DIRTY_TIME; 198 spin_unlock(&inode->i_lock); 199 mark_inode_dirty_sync(inode); 200 } 201 return file->f_op->fsync(file, start, end, datasync); 202 } 203 EXPORT_SYMBOL(vfs_fsync_range); 204 205 /** 206 * vfs_fsync - perform a fsync or fdatasync on a file 207 * @file: file to sync 208 * @datasync: only perform a fdatasync operation 209 * 210 * Write back data and metadata for @file to disk. If @datasync is 211 * set only metadata needed to access modified file data is written. 212 */ 213 int vfs_fsync(struct file *file, int datasync) 214 { 215 return vfs_fsync_range(file, 0, LLONG_MAX, datasync); 216 } 217 EXPORT_SYMBOL(vfs_fsync); 218 219 static int do_fsync(unsigned int fd, int datasync) 220 { 221 struct fd f = fdget(fd); 222 int ret = -EBADF; 223 224 if (f.file) { 225 ret = vfs_fsync(f.file, datasync); 226 fdput(f); 227 } 228 return ret; 229 } 230 231 SYSCALL_DEFINE1(fsync, unsigned int, fd) 232 { 233 return do_fsync(fd, 0); 234 } 235 236 SYSCALL_DEFINE1(fdatasync, unsigned int, fd) 237 { 238 return do_fsync(fd, 1); 239 } 240 241 /* 242 * sys_sync_file_range() permits finely controlled syncing over a segment of 243 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is 244 * zero then sys_sync_file_range() will operate from offset out to EOF. 245 * 246 * The flag bits are: 247 * 248 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range 249 * before performing the write. 250 * 251 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the 252 * range which are not presently under writeback. Note that this may block for 253 * significant periods due to exhaustion of disk request structures. 254 * 255 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range 256 * after performing the write. 257 * 258 * Useful combinations of the flag bits are: 259 * 260 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages 261 * in the range which were dirty on entry to sys_sync_file_range() are placed 262 * under writeout. This is a start-write-for-data-integrity operation. 263 * 264 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which 265 * are not presently under writeout. This is an asynchronous flush-to-disk 266 * operation. Not suitable for data integrity operations. 267 * 268 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for 269 * completion of writeout of all pages in the range. This will be used after an 270 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait 271 * for that operation to complete and to return the result. 272 * 273 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: 274 * a traditional sync() operation. This is a write-for-data-integrity operation 275 * which will ensure that all pages in the range which were dirty on entry to 276 * sys_sync_file_range() are committed to disk. 277 * 278 * 279 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any 280 * I/O errors or ENOSPC conditions and will return those to the caller, after 281 * clearing the EIO and ENOSPC flags in the address_space. 282 * 283 * It should be noted that none of these operations write out the file's 284 * metadata. So unless the application is strictly performing overwrites of 285 * already-instantiated disk blocks, there are no guarantees here that the data 286 * will be available after a crash. 287 */ 288 int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes, 289 unsigned int flags) 290 { 291 int ret; 292 struct fd f; 293 struct address_space *mapping; 294 loff_t endbyte; /* inclusive */ 295 umode_t i_mode; 296 297 ret = -EINVAL; 298 if (flags & ~VALID_FLAGS) 299 goto out; 300 301 endbyte = offset + nbytes; 302 303 if ((s64)offset < 0) 304 goto out; 305 if ((s64)endbyte < 0) 306 goto out; 307 if (endbyte < offset) 308 goto out; 309 310 if (sizeof(pgoff_t) == 4) { 311 if (offset >= (0x100000000ULL << PAGE_SHIFT)) { 312 /* 313 * The range starts outside a 32 bit machine's 314 * pagecache addressing capabilities. Let it "succeed" 315 */ 316 ret = 0; 317 goto out; 318 } 319 if (endbyte >= (0x100000000ULL << PAGE_SHIFT)) { 320 /* 321 * Out to EOF 322 */ 323 nbytes = 0; 324 } 325 } 326 327 if (nbytes == 0) 328 endbyte = LLONG_MAX; 329 else 330 endbyte--; /* inclusive */ 331 332 ret = -EBADF; 333 f = fdget(fd); 334 if (!f.file) 335 goto out; 336 337 i_mode = file_inode(f.file)->i_mode; 338 ret = -ESPIPE; 339 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && 340 !S_ISLNK(i_mode)) 341 goto out_put; 342 343 mapping = f.file->f_mapping; 344 ret = 0; 345 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { 346 ret = file_fdatawait_range(f.file, offset, endbyte); 347 if (ret < 0) 348 goto out_put; 349 } 350 351 if (flags & SYNC_FILE_RANGE_WRITE) { 352 ret = __filemap_fdatawrite_range(mapping, offset, endbyte, 353 WB_SYNC_NONE); 354 if (ret < 0) 355 goto out_put; 356 } 357 358 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) 359 ret = file_fdatawait_range(f.file, offset, endbyte); 360 361 out_put: 362 fdput(f); 363 out: 364 return ret; 365 } 366 367 SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes, 368 unsigned int, flags) 369 { 370 return ksys_sync_file_range(fd, offset, nbytes, flags); 371 } 372 373 /* It would be nice if people remember that not all the world's an i386 374 when they introduce new system calls */ 375 SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags, 376 loff_t, offset, loff_t, nbytes) 377 { 378 return ksys_sync_file_range(fd, offset, nbytes, flags); 379 } 380