1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * High-level sync()-related operations 4 */ 5 6 #include <linux/blkdev.h> 7 #include <linux/kernel.h> 8 #include <linux/file.h> 9 #include <linux/fs.h> 10 #include <linux/slab.h> 11 #include <linux/export.h> 12 #include <linux/namei.h> 13 #include <linux/sched.h> 14 #include <linux/writeback.h> 15 #include <linux/syscalls.h> 16 #include <linux/linkage.h> 17 #include <linux/pagemap.h> 18 #include <linux/quotaops.h> 19 #include <linux/backing-dev.h> 20 #include "internal.h" 21 22 #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \ 23 SYNC_FILE_RANGE_WAIT_AFTER) 24 25 /* 26 * Write out and wait upon all dirty data associated with this 27 * superblock. Filesystem data as well as the underlying block 28 * device. Takes the superblock lock. 29 */ 30 int sync_filesystem(struct super_block *sb) 31 { 32 int ret = 0; 33 34 /* 35 * We need to be protected against the filesystem going from 36 * r/o to r/w or vice versa. 37 */ 38 WARN_ON(!rwsem_is_locked(&sb->s_umount)); 39 40 /* 41 * No point in syncing out anything if the filesystem is read-only. 42 */ 43 if (sb_rdonly(sb)) 44 return 0; 45 46 /* 47 * Do the filesystem syncing work. For simple filesystems 48 * writeback_inodes_sb(sb) just dirties buffers with inodes so we have 49 * to submit I/O for these buffers via sync_blockdev(). This also 50 * speeds up the wait == 1 case since in that case write_inode() 51 * methods call sync_dirty_buffer() and thus effectively write one block 52 * at a time. 53 */ 54 writeback_inodes_sb(sb, WB_REASON_SYNC); 55 if (sb->s_op->sync_fs) { 56 ret = sb->s_op->sync_fs(sb, 0); 57 if (ret) 58 return ret; 59 } 60 ret = sync_blockdev_nowait(sb->s_bdev); 61 if (ret) 62 return ret; 63 64 sync_inodes_sb(sb); 65 if (sb->s_op->sync_fs) { 66 ret = sb->s_op->sync_fs(sb, 1); 67 if (ret) 68 return ret; 69 } 70 return sync_blockdev(sb->s_bdev); 71 } 72 EXPORT_SYMBOL(sync_filesystem); 73 74 static void sync_inodes_one_sb(struct super_block *sb, void *arg) 75 { 76 if (!sb_rdonly(sb)) 77 sync_inodes_sb(sb); 78 } 79 80 static void sync_fs_one_sb(struct super_block *sb, void *arg) 81 { 82 if (!sb_rdonly(sb) && !(sb->s_iflags & SB_I_SKIP_SYNC) && 83 sb->s_op->sync_fs) 84 sb->s_op->sync_fs(sb, *(int *)arg); 85 } 86 87 /* 88 * Sync everything. We start by waking flusher threads so that most of 89 * writeback runs on all devices in parallel. Then we sync all inodes reliably 90 * which effectively also waits for all flusher threads to finish doing 91 * writeback. At this point all data is on disk so metadata should be stable 92 * and we tell filesystems to sync their metadata via ->sync_fs() calls. 93 * Finally, we writeout all block devices because some filesystems (e.g. ext2) 94 * just write metadata (such as inodes or bitmaps) to block device page cache 95 * and do not sync it on their own in ->sync_fs(). 96 */ 97 void ksys_sync(void) 98 { 99 int nowait = 0, wait = 1; 100 101 wakeup_flusher_threads(WB_REASON_SYNC); 102 iterate_supers(sync_inodes_one_sb, NULL); 103 iterate_supers(sync_fs_one_sb, &nowait); 104 iterate_supers(sync_fs_one_sb, &wait); 105 sync_bdevs(false); 106 sync_bdevs(true); 107 if (unlikely(laptop_mode)) 108 laptop_sync_completion(); 109 } 110 111 SYSCALL_DEFINE0(sync) 112 { 113 ksys_sync(); 114 return 0; 115 } 116 117 static void do_sync_work(struct work_struct *work) 118 { 119 int nowait = 0; 120 int wait = 1; 121 122 /* 123 * Sync twice to reduce the possibility we skipped some inodes / pages 124 * because they were temporarily locked 125 */ 126 iterate_supers(sync_inodes_one_sb, NULL); 127 iterate_supers(sync_fs_one_sb, &nowait); 128 sync_bdevs(false); 129 iterate_supers(sync_inodes_one_sb, NULL); 130 iterate_supers(sync_fs_one_sb, &wait); 131 sync_bdevs(false); 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 * sync a single super 149 */ 150 SYSCALL_DEFINE1(syncfs, int, fd) 151 { 152 CLASS(fd, f)(fd); 153 struct super_block *sb; 154 int ret, ret2; 155 156 if (fd_empty(f)) 157 return -EBADF; 158 sb = fd_file(f)->f_path.dentry->d_sb; 159 160 down_read(&sb->s_umount); 161 ret = sync_filesystem(sb); 162 up_read(&sb->s_umount); 163 164 ret2 = errseq_check_and_advance(&sb->s_wb_err, &fd_file(f)->f_sb_err); 165 166 return ret ? ret : ret2; 167 } 168 169 /** 170 * vfs_fsync_range - helper to sync a range of data & metadata to disk 171 * @file: file to sync 172 * @start: offset in bytes of the beginning of data range to sync 173 * @end: offset in bytes of the end of data range (inclusive) 174 * @datasync: perform only datasync 175 * 176 * Write back data in range @start..@end and metadata for @file to disk. If 177 * @datasync is set only metadata needed to access modified file data is 178 * written. 179 */ 180 int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) 181 { 182 struct inode *inode = file->f_mapping->host; 183 184 if (!file->f_op->fsync) 185 return -EINVAL; 186 if (!datasync && (inode_state_read_once(inode) & I_DIRTY_TIME)) 187 mark_inode_dirty_sync(inode); 188 return file->f_op->fsync(file, start, end, datasync); 189 } 190 EXPORT_SYMBOL(vfs_fsync_range); 191 192 /** 193 * vfs_fsync - perform a fsync or fdatasync on a file 194 * @file: file to sync 195 * @datasync: only perform a fdatasync operation 196 * 197 * Write back data and metadata for @file to disk. If @datasync is 198 * set only metadata needed to access modified file data is written. 199 */ 200 int vfs_fsync(struct file *file, int datasync) 201 { 202 return vfs_fsync_range(file, 0, LLONG_MAX, datasync); 203 } 204 EXPORT_SYMBOL(vfs_fsync); 205 206 static int do_fsync(unsigned int fd, int datasync) 207 { 208 CLASS(fd, f)(fd); 209 210 if (fd_empty(f)) 211 return -EBADF; 212 213 return vfs_fsync(fd_file(f), datasync); 214 } 215 216 SYSCALL_DEFINE1(fsync, unsigned int, fd) 217 { 218 return do_fsync(fd, 0); 219 } 220 221 SYSCALL_DEFINE1(fdatasync, unsigned int, fd) 222 { 223 return do_fsync(fd, 1); 224 } 225 226 int sync_file_range(struct file *file, loff_t offset, loff_t nbytes, 227 unsigned int flags) 228 { 229 int ret; 230 struct address_space *mapping; 231 loff_t endbyte; /* inclusive */ 232 umode_t i_mode; 233 234 ret = -EINVAL; 235 if (flags & ~VALID_FLAGS) 236 goto out; 237 238 endbyte = offset + nbytes; 239 240 if ((s64)offset < 0) 241 goto out; 242 if ((s64)endbyte < 0) 243 goto out; 244 if (endbyte < offset) 245 goto out; 246 247 if (sizeof(pgoff_t) == 4) { 248 if (offset >= (0x100000000ULL << PAGE_SHIFT)) { 249 /* 250 * The range starts outside a 32 bit machine's 251 * pagecache addressing capabilities. Let it "succeed" 252 */ 253 ret = 0; 254 goto out; 255 } 256 if (endbyte >= (0x100000000ULL << PAGE_SHIFT)) { 257 /* 258 * Out to EOF 259 */ 260 nbytes = 0; 261 } 262 } 263 264 if (nbytes == 0) 265 endbyte = LLONG_MAX; 266 else 267 endbyte--; /* inclusive */ 268 269 i_mode = file_inode(file)->i_mode; 270 ret = -ESPIPE; 271 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && 272 !S_ISLNK(i_mode)) 273 goto out; 274 275 mapping = file->f_mapping; 276 ret = 0; 277 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { 278 ret = file_fdatawait_range(file, offset, endbyte); 279 if (ret < 0) 280 goto out; 281 } 282 283 if (flags & SYNC_FILE_RANGE_WRITE) { 284 if ((flags & SYNC_FILE_RANGE_WRITE_AND_WAIT) == 285 SYNC_FILE_RANGE_WRITE_AND_WAIT) 286 ret = filemap_fdatawrite_range(mapping, offset, 287 endbyte); 288 else 289 ret = filemap_flush_range(mapping, offset, endbyte); 290 if (ret < 0) 291 goto out; 292 } 293 294 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) 295 ret = file_fdatawait_range(file, offset, endbyte); 296 297 out: 298 return ret; 299 } 300 301 /* 302 * ksys_sync_file_range() permits finely controlled syncing over a segment of 303 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is 304 * zero then ksys_sync_file_range() will operate from offset out to EOF. 305 * 306 * The flag bits are: 307 * 308 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range 309 * before performing the write. 310 * 311 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the 312 * range which are not presently under writeback. Note that this may block for 313 * significant periods due to exhaustion of disk request structures. 314 * 315 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range 316 * after performing the write. 317 * 318 * Useful combinations of the flag bits are: 319 * 320 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages 321 * in the range which were dirty on entry to ksys_sync_file_range() are placed 322 * under writeout. This is a start-write-for-data-integrity operation. 323 * 324 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which 325 * are not presently under writeout. This is an asynchronous flush-to-disk 326 * operation. Not suitable for data integrity operations. 327 * 328 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for 329 * completion of writeout of all pages in the range. This will be used after an 330 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait 331 * for that operation to complete and to return the result. 332 * 333 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER 334 * (a.k.a. SYNC_FILE_RANGE_WRITE_AND_WAIT): 335 * a traditional sync() operation. This is a write-for-data-integrity operation 336 * which will ensure that all pages in the range which were dirty on entry to 337 * ksys_sync_file_range() are written to disk. It should be noted that disk 338 * caches are not flushed by this call, so there are no guarantees here that the 339 * data will be available on disk after a crash. 340 * 341 * 342 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any 343 * I/O errors or ENOSPC conditions and will return those to the caller, after 344 * clearing the EIO and ENOSPC flags in the address_space. 345 * 346 * It should be noted that none of these operations write out the file's 347 * metadata. So unless the application is strictly performing overwrites of 348 * already-instantiated disk blocks, there are no guarantees here that the data 349 * will be available after a crash. 350 */ 351 int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes, 352 unsigned int flags) 353 { 354 CLASS(fd, f)(fd); 355 356 if (fd_empty(f)) 357 return -EBADF; 358 359 return sync_file_range(fd_file(f), offset, nbytes, flags); 360 } 361 362 SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes, 363 unsigned int, flags) 364 { 365 return ksys_sync_file_range(fd, offset, nbytes, flags); 366 } 367 368 #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_SYNC_FILE_RANGE) 369 COMPAT_SYSCALL_DEFINE6(sync_file_range, int, fd, compat_arg_u64_dual(offset), 370 compat_arg_u64_dual(nbytes), unsigned int, flags) 371 { 372 return ksys_sync_file_range(fd, compat_arg_u64_glue(offset), 373 compat_arg_u64_glue(nbytes), flags); 374 } 375 #endif 376 377 /* It would be nice if people remember that not all the world's an i386 378 when they introduce new system calls */ 379 SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags, 380 loff_t, offset, loff_t, nbytes) 381 { 382 return ksys_sync_file_range(fd, offset, nbytes, flags); 383 } 384