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 */ sync_filesystem(struct super_block * sb)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 sync_inodes_one_sb(struct super_block * sb,void * arg)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 sync_fs_one_sb(struct super_block * sb,void * arg)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 */ ksys_sync(void)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 SYSCALL_DEFINE0(sync)111 SYSCALL_DEFINE0(sync) 112 { 113 ksys_sync(); 114 return 0; 115 } 116 do_sync_work(struct work_struct * work)117 static void do_sync_work(struct work_struct *work) 118 { 119 int nowait = 0; 120 121 /* 122 * Sync twice to reduce the possibility we skipped some inodes / pages 123 * because they were temporarily locked 124 */ 125 iterate_supers(sync_inodes_one_sb, &nowait); 126 iterate_supers(sync_fs_one_sb, &nowait); 127 sync_bdevs(false); 128 iterate_supers(sync_inodes_one_sb, &nowait); 129 iterate_supers(sync_fs_one_sb, &nowait); 130 sync_bdevs(false); 131 printk("Emergency Sync complete\n"); 132 kfree(work); 133 } 134 emergency_sync(void)135 void emergency_sync(void) 136 { 137 struct work_struct *work; 138 139 work = kmalloc(sizeof(*work), GFP_ATOMIC); 140 if (work) { 141 INIT_WORK(work, do_sync_work); 142 schedule_work(work); 143 } 144 } 145 146 /* 147 * sync a single super 148 */ SYSCALL_DEFINE1(syncfs,int,fd)149 SYSCALL_DEFINE1(syncfs, int, fd) 150 { 151 struct fd f = fdget(fd); 152 struct super_block *sb; 153 int ret, ret2; 154 155 if (!f.file) 156 return -EBADF; 157 sb = f.file->f_path.dentry->d_sb; 158 159 down_read(&sb->s_umount); 160 ret = sync_filesystem(sb); 161 up_read(&sb->s_umount); 162 163 ret2 = errseq_check_and_advance(&sb->s_wb_err, &f.file->f_sb_err); 164 165 fdput(f); 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 */ vfs_fsync_range(struct file * file,loff_t start,loff_t end,int datasync)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->i_state & 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 */ vfs_fsync(struct file * file,int datasync)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 do_fsync(unsigned int fd,int datasync)206 static int do_fsync(unsigned int fd, int datasync) 207 { 208 struct fd f = fdget(fd); 209 int ret = -EBADF; 210 211 if (f.file) { 212 ret = vfs_fsync(f.file, datasync); 213 fdput(f); 214 } 215 return ret; 216 } 217 SYSCALL_DEFINE1(fsync,unsigned int,fd)218 SYSCALL_DEFINE1(fsync, unsigned int, fd) 219 { 220 return do_fsync(fd, 0); 221 } 222 SYSCALL_DEFINE1(fdatasync,unsigned int,fd)223 SYSCALL_DEFINE1(fdatasync, unsigned int, fd) 224 { 225 return do_fsync(fd, 1); 226 } 227 sync_file_range(struct file * file,loff_t offset,loff_t nbytes,unsigned int flags)228 int sync_file_range(struct file *file, loff_t offset, loff_t nbytes, 229 unsigned int flags) 230 { 231 int ret; 232 struct address_space *mapping; 233 loff_t endbyte; /* inclusive */ 234 umode_t i_mode; 235 236 ret = -EINVAL; 237 if (flags & ~VALID_FLAGS) 238 goto out; 239 240 endbyte = offset + nbytes; 241 242 if ((s64)offset < 0) 243 goto out; 244 if ((s64)endbyte < 0) 245 goto out; 246 if (endbyte < offset) 247 goto out; 248 249 if (sizeof(pgoff_t) == 4) { 250 if (offset >= (0x100000000ULL << PAGE_SHIFT)) { 251 /* 252 * The range starts outside a 32 bit machine's 253 * pagecache addressing capabilities. Let it "succeed" 254 */ 255 ret = 0; 256 goto out; 257 } 258 if (endbyte >= (0x100000000ULL << PAGE_SHIFT)) { 259 /* 260 * Out to EOF 261 */ 262 nbytes = 0; 263 } 264 } 265 266 if (nbytes == 0) 267 endbyte = LLONG_MAX; 268 else 269 endbyte--; /* inclusive */ 270 271 i_mode = file_inode(file)->i_mode; 272 ret = -ESPIPE; 273 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && 274 !S_ISLNK(i_mode)) 275 goto out; 276 277 mapping = file->f_mapping; 278 ret = 0; 279 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { 280 ret = file_fdatawait_range(file, offset, endbyte); 281 if (ret < 0) 282 goto out; 283 } 284 285 if (flags & SYNC_FILE_RANGE_WRITE) { 286 int sync_mode = WB_SYNC_NONE; 287 288 if ((flags & SYNC_FILE_RANGE_WRITE_AND_WAIT) == 289 SYNC_FILE_RANGE_WRITE_AND_WAIT) 290 sync_mode = WB_SYNC_ALL; 291 292 ret = __filemap_fdatawrite_range(mapping, offset, endbyte, 293 sync_mode); 294 if (ret < 0) 295 goto out; 296 } 297 298 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) 299 ret = file_fdatawait_range(file, offset, endbyte); 300 301 out: 302 return ret; 303 } 304 305 /* 306 * ksys_sync_file_range() permits finely controlled syncing over a segment of 307 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is 308 * zero then ksys_sync_file_range() will operate from offset out to EOF. 309 * 310 * The flag bits are: 311 * 312 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range 313 * before performing the write. 314 * 315 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the 316 * range which are not presently under writeback. Note that this may block for 317 * significant periods due to exhaustion of disk request structures. 318 * 319 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range 320 * after performing the write. 321 * 322 * Useful combinations of the flag bits are: 323 * 324 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages 325 * in the range which were dirty on entry to ksys_sync_file_range() are placed 326 * under writeout. This is a start-write-for-data-integrity operation. 327 * 328 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which 329 * are not presently under writeout. This is an asynchronous flush-to-disk 330 * operation. Not suitable for data integrity operations. 331 * 332 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for 333 * completion of writeout of all pages in the range. This will be used after an 334 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait 335 * for that operation to complete and to return the result. 336 * 337 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER 338 * (a.k.a. SYNC_FILE_RANGE_WRITE_AND_WAIT): 339 * a traditional sync() operation. This is a write-for-data-integrity operation 340 * which will ensure that all pages in the range which were dirty on entry to 341 * ksys_sync_file_range() are written to disk. It should be noted that disk 342 * caches are not flushed by this call, so there are no guarantees here that the 343 * data will be available on disk after a crash. 344 * 345 * 346 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any 347 * I/O errors or ENOSPC conditions and will return those to the caller, after 348 * clearing the EIO and ENOSPC flags in the address_space. 349 * 350 * It should be noted that none of these operations write out the file's 351 * metadata. So unless the application is strictly performing overwrites of 352 * already-instantiated disk blocks, there are no guarantees here that the data 353 * will be available after a crash. 354 */ ksys_sync_file_range(int fd,loff_t offset,loff_t nbytes,unsigned int flags)355 int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes, 356 unsigned int flags) 357 { 358 int ret; 359 struct fd f; 360 361 ret = -EBADF; 362 f = fdget(fd); 363 if (f.file) 364 ret = sync_file_range(f.file, offset, nbytes, flags); 365 366 fdput(f); 367 return ret; 368 } 369 SYSCALL_DEFINE4(sync_file_range,int,fd,loff_t,offset,loff_t,nbytes,unsigned int,flags)370 SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes, 371 unsigned int, flags) 372 { 373 return ksys_sync_file_range(fd, offset, nbytes, flags); 374 } 375 376 #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_SYNC_FILE_RANGE) COMPAT_SYSCALL_DEFINE6(sync_file_range,int,fd,compat_arg_u64_dual (offset),compat_arg_u64_dual (nbytes),unsigned int,flags)377 COMPAT_SYSCALL_DEFINE6(sync_file_range, int, fd, compat_arg_u64_dual(offset), 378 compat_arg_u64_dual(nbytes), unsigned int, flags) 379 { 380 return ksys_sync_file_range(fd, compat_arg_u64_glue(offset), 381 compat_arg_u64_glue(nbytes), flags); 382 } 383 #endif 384 385 /* It would be nice if people remember that not all the world's an i386 386 when they introduce new system calls */ SYSCALL_DEFINE4(sync_file_range2,int,fd,unsigned int,flags,loff_t,offset,loff_t,nbytes)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