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 } 108 109 SYSCALL_DEFINE0(sync) 110 { 111 ksys_sync(); 112 return 0; 113 } 114 115 static void do_sync_work(struct work_struct *work) 116 { 117 int nowait = 0; 118 int wait = 1; 119 120 /* 121 * Sync twice to reduce the possibility we skipped some inodes / pages 122 * because they were temporarily locked 123 */ 124 iterate_supers(sync_inodes_one_sb, NULL); 125 iterate_supers(sync_fs_one_sb, &nowait); 126 sync_bdevs(false); 127 iterate_supers(sync_inodes_one_sb, NULL); 128 iterate_supers(sync_fs_one_sb, &wait); 129 sync_bdevs(false); 130 printk("Emergency Sync complete\n"); 131 kfree(work); 132 } 133 134 void emergency_sync(void) 135 { 136 struct work_struct *work; 137 138 work = kmalloc(sizeof(*work), GFP_ATOMIC); 139 if (work) { 140 INIT_WORK(work, do_sync_work); 141 schedule_work(work); 142 } 143 } 144 145 /* 146 * sync a single super 147 */ 148 SYSCALL_DEFINE1(syncfs, int, fd) 149 { 150 CLASS(fd, f)(fd); 151 struct super_block *sb; 152 int ret, ret2; 153 154 if (fd_empty(f)) 155 return -EBADF; 156 sb = fd_file(f)->f_path.dentry->d_sb; 157 158 down_read(&sb->s_umount); 159 ret = sync_filesystem(sb); 160 up_read(&sb->s_umount); 161 162 ret2 = errseq_check_and_advance(&sb->s_wb_err, &fd_file(f)->f_sb_err); 163 164 return ret ? ret : ret2; 165 } 166 167 /** 168 * vfs_fsync_range - helper to sync a range of data & metadata to disk 169 * @file: file to sync 170 * @start: offset in bytes of the beginning of data range to sync 171 * @end: offset in bytes of the end of data range (inclusive) 172 * @datasync: perform only datasync 173 * 174 * Write back data in range @start..@end and metadata for @file to disk. If 175 * @datasync is set only metadata needed to access modified file data is 176 * written. 177 */ 178 int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) 179 { 180 struct inode *inode = file->f_mapping->host; 181 182 if (!file->f_op->fsync) 183 return -EINVAL; 184 if (!datasync) 185 sync_lazytime(inode); 186 return file->f_op->fsync(file, start, end, datasync); 187 } 188 EXPORT_SYMBOL(vfs_fsync_range); 189 190 /** 191 * vfs_fsync - perform a fsync or fdatasync on a file 192 * @file: file to sync 193 * @datasync: only perform a fdatasync operation 194 * 195 * Write back data and metadata for @file to disk. If @datasync is 196 * set only metadata needed to access modified file data is written. 197 */ 198 int vfs_fsync(struct file *file, int datasync) 199 { 200 return vfs_fsync_range(file, 0, LLONG_MAX, datasync); 201 } 202 EXPORT_SYMBOL(vfs_fsync); 203 204 static int do_fsync(unsigned int fd, int datasync) 205 { 206 CLASS(fd, f)(fd); 207 208 if (fd_empty(f)) 209 return -EBADF; 210 211 return vfs_fsync(fd_file(f), datasync); 212 } 213 214 SYSCALL_DEFINE1(fsync, unsigned int, fd) 215 { 216 return do_fsync(fd, 0); 217 } 218 219 SYSCALL_DEFINE1(fdatasync, unsigned int, fd) 220 { 221 return do_fsync(fd, 1); 222 } 223 224 int sync_file_range(struct file *file, loff_t offset, loff_t nbytes, 225 unsigned int flags) 226 { 227 int ret; 228 struct address_space *mapping; 229 loff_t endbyte; /* inclusive */ 230 umode_t i_mode; 231 232 ret = -EINVAL; 233 if (flags & ~VALID_FLAGS) 234 goto out; 235 236 endbyte = offset + nbytes; 237 238 if ((s64)offset < 0) 239 goto out; 240 if ((s64)endbyte < 0) 241 goto out; 242 if (endbyte < offset) 243 goto out; 244 245 if (sizeof(pgoff_t) == 4) { 246 if (offset >= (0x100000000ULL << PAGE_SHIFT)) { 247 /* 248 * The range starts outside a 32 bit machine's 249 * pagecache addressing capabilities. Let it "succeed" 250 */ 251 ret = 0; 252 goto out; 253 } 254 if (endbyte >= (0x100000000ULL << PAGE_SHIFT)) { 255 /* 256 * Out to EOF 257 */ 258 nbytes = 0; 259 } 260 } 261 262 if (nbytes == 0) 263 endbyte = LLONG_MAX; 264 else 265 endbyte--; /* inclusive */ 266 267 i_mode = file_inode(file)->i_mode; 268 ret = -ESPIPE; 269 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && 270 !S_ISLNK(i_mode)) 271 goto out; 272 273 mapping = file->f_mapping; 274 ret = 0; 275 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { 276 ret = file_fdatawait_range(file, offset, endbyte); 277 if (ret < 0) 278 goto out; 279 } 280 281 if (flags & SYNC_FILE_RANGE_WRITE) { 282 if ((flags & SYNC_FILE_RANGE_WRITE_AND_WAIT) == 283 SYNC_FILE_RANGE_WRITE_AND_WAIT) 284 ret = filemap_fdatawrite_range(mapping, offset, 285 endbyte); 286 else 287 ret = filemap_flush_range(mapping, offset, endbyte); 288 if (ret < 0) 289 goto out; 290 } 291 292 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) 293 ret = file_fdatawait_range(file, offset, endbyte); 294 295 out: 296 return ret; 297 } 298 299 /* 300 * ksys_sync_file_range() permits finely controlled syncing over a segment of 301 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is 302 * zero then ksys_sync_file_range() will operate from offset out to EOF. 303 * 304 * The flag bits are: 305 * 306 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range 307 * before performing the write. 308 * 309 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the 310 * range which are not presently under writeback. Note that this may block for 311 * significant periods due to exhaustion of disk request structures. 312 * 313 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range 314 * after performing the write. 315 * 316 * Useful combinations of the flag bits are: 317 * 318 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages 319 * in the range which were dirty on entry to ksys_sync_file_range() are placed 320 * under writeout. This is a start-write-for-data-integrity operation. 321 * 322 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which 323 * are not presently under writeout. This is an asynchronous flush-to-disk 324 * operation. Not suitable for data integrity operations. 325 * 326 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for 327 * completion of writeout of all pages in the range. This will be used after an 328 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait 329 * for that operation to complete and to return the result. 330 * 331 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER 332 * (a.k.a. SYNC_FILE_RANGE_WRITE_AND_WAIT): 333 * a traditional sync() operation. This is a write-for-data-integrity operation 334 * which will ensure that all pages in the range which were dirty on entry to 335 * ksys_sync_file_range() are written to disk. It should be noted that disk 336 * caches are not flushed by this call, so there are no guarantees here that the 337 * data will be available on disk after a crash. 338 * 339 * 340 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any 341 * I/O errors or ENOSPC conditions and will return those to the caller, after 342 * clearing the EIO and ENOSPC flags in the address_space. 343 * 344 * It should be noted that none of these operations write out the file's 345 * metadata. So unless the application is strictly performing overwrites of 346 * already-instantiated disk blocks, there are no guarantees here that the data 347 * will be available after a crash. 348 */ 349 int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes, 350 unsigned int flags) 351 { 352 CLASS(fd, f)(fd); 353 354 if (fd_empty(f)) 355 return -EBADF; 356 357 return sync_file_range(fd_file(f), offset, nbytes, flags); 358 } 359 360 SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes, 361 unsigned int, flags) 362 { 363 return ksys_sync_file_range(fd, offset, nbytes, flags); 364 } 365 366 #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_SYNC_FILE_RANGE) 367 COMPAT_SYSCALL_DEFINE6(sync_file_range, int, fd, compat_arg_u64_dual(offset), 368 compat_arg_u64_dual(nbytes), unsigned int, flags) 369 { 370 return ksys_sync_file_range(fd, compat_arg_u64_glue(offset), 371 compat_arg_u64_glue(nbytes), flags); 372 } 373 #endif 374 375 /* It would be nice if people remember that not all the world's an i386 376 when they introduce new system calls */ 377 SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags, 378 loff_t, offset, loff_t, nbytes) 379 { 380 return ksys_sync_file_range(fd, offset, nbytes, flags); 381 } 382