2 * High-level sync()-related operations
5 #include <linux/kernel.h>
6 #include <linux/file.h>
8 #include <linux/module.h>
9 #include <linux/sched.h>
10 #include <linux/writeback.h>
11 #include <linux/syscalls.h>
12 #include <linux/linkage.h>
13 #include <linux/pagemap.h>
14 #include <linux/quotaops.h>
15 #include <linux/buffer_head.h>
18 #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
19 SYNC_FILE_RANGE_WAIT_AFTER)
22 * Do the filesystem syncing work. For simple filesystems
23 * writeback_inodes_sb(sb) just dirties buffers with inodes so we have to
24 * submit IO for these buffers via __sync_blockdev(). This also speeds up the
25 * wait == 1 case since in that case write_inode() functions do
26 * sync_dirty_buffer() and thus effectively write one block at a time.
28 static int __sync_filesystem(struct super_block *sb, int wait)
31 * This should be safe, as we require bdi backing to actually
32 * write out data in the first place
37 /* Avoid doing twice syncing and cache pruning for quota sync */
39 writeout_quota_sb(sb, -1);
40 writeback_inodes_sb(sb);
42 sync_quota_sb(sb, -1);
45 if (sb->s_op->sync_fs)
46 sb->s_op->sync_fs(sb, wait);
47 return __sync_blockdev(sb->s_bdev, wait);
51 * Write out and wait upon all dirty data associated with this
52 * superblock. Filesystem data as well as the underlying block
53 * device. Takes the superblock lock.
55 int sync_filesystem(struct super_block *sb)
60 * We need to be protected against the filesystem going from
61 * r/o to r/w or vice versa.
63 WARN_ON(!rwsem_is_locked(&sb->s_umount));
66 * No point in syncing out anything if the filesystem is read-only.
68 if (sb->s_flags & MS_RDONLY)
71 ret = __sync_filesystem(sb, 0);
74 return __sync_filesystem(sb, 1);
76 EXPORT_SYMBOL_GPL(sync_filesystem);
79 * Sync all the data for all the filesystems (called by sys_sync() and
82 * This operation is careful to avoid the livelock which could easily happen
83 * if two or more filesystems are being continuously dirtied. s_need_sync
84 * is used only here. We set it against all filesystems and then clear it as
85 * we sync them. So redirtied filesystems are skipped.
87 * But if process A is currently running sync_filesystems and then process B
88 * calls sync_filesystems as well, process B will set all the s_need_sync
89 * flags again, which will cause process A to resync everything. Fix that with
92 static void sync_filesystems(int wait)
94 struct super_block *sb;
95 static DEFINE_MUTEX(mutex);
97 mutex_lock(&mutex); /* Could be down_interruptible */
99 list_for_each_entry(sb, &super_blocks, s_list)
103 list_for_each_entry(sb, &super_blocks, s_list) {
104 if (!sb->s_need_sync)
108 spin_unlock(&sb_lock);
110 down_read(&sb->s_umount);
111 if (!(sb->s_flags & MS_RDONLY) && sb->s_root && sb->s_bdi)
112 __sync_filesystem(sb, wait);
113 up_read(&sb->s_umount);
115 /* restart only when sb is no longer on the list */
117 if (__put_super_and_need_restart(sb))
120 spin_unlock(&sb_lock);
121 mutex_unlock(&mutex);
125 * sync everything. Start out by waking pdflush, because that writes back
126 * all queues in parallel.
128 SYSCALL_DEFINE0(sync)
130 wakeup_flusher_threads(0);
133 if (unlikely(laptop_mode))
134 laptop_sync_completion();
138 static void do_sync_work(struct work_struct *work)
141 * Sync twice to reduce the possibility we skipped some inodes / pages
142 * because they were temporarily locked
146 printk("Emergency Sync complete\n");
150 void emergency_sync(void)
152 struct work_struct *work;
154 work = kmalloc(sizeof(*work), GFP_ATOMIC);
156 INIT_WORK(work, do_sync_work);
162 * Generic function to fsync a file.
164 * filp may be NULL if called via the msync of a vma.
166 int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
168 struct inode * inode = dentry->d_inode;
169 struct super_block * sb;
172 /* sync the inode to buffers */
173 ret = write_inode_now(inode, 0);
175 /* sync the superblock to buffers */
177 if (sb->s_dirt && sb->s_op->write_super)
178 sb->s_op->write_super(sb);
180 /* .. finally sync the buffers to disk */
181 err = sync_blockdev(sb->s_bdev);
188 * vfs_fsync_range - helper to sync a range of data & metadata to disk
189 * @file: file to sync
190 * @dentry: dentry of @file
191 * @start: offset in bytes of the beginning of data range to sync
192 * @end: offset in bytes of the end of data range (inclusive)
193 * @datasync: perform only datasync
195 * Write back data in range @start..@end and metadata for @file to disk. If
196 * @datasync is set only metadata needed to access modified file data is
199 * In case this function is called from nfsd @file may be %NULL and
200 * only @dentry is set. This can only happen when the filesystem
201 * implements the export_operations API.
203 int vfs_fsync_range(struct file *file, struct dentry *dentry, loff_t start,
204 loff_t end, int datasync)
206 const struct file_operations *fop;
207 struct address_space *mapping;
211 * Get mapping and operations from the file in case we have
212 * as file, or get the default values for them in case we
213 * don't have a struct file available. Damn nfsd..
216 mapping = file->f_mapping;
219 mapping = dentry->d_inode->i_mapping;
220 fop = dentry->d_inode->i_fop;
223 if (!fop || !fop->fsync) {
228 ret = filemap_write_and_wait_range(mapping, start, end);
231 * We need to protect against concurrent writers, which could cause
232 * livelocks in fsync_buffers_list().
234 mutex_lock(&mapping->host->i_mutex);
235 err = fop->fsync(file, dentry, datasync);
238 mutex_unlock(&mapping->host->i_mutex);
243 EXPORT_SYMBOL(vfs_fsync_range);
246 * vfs_fsync - perform a fsync or fdatasync on a file
247 * @file: file to sync
248 * @dentry: dentry of @file
249 * @datasync: only perform a fdatasync operation
251 * Write back data and metadata for @file to disk. If @datasync is
252 * set only metadata needed to access modified file data is written.
254 * In case this function is called from nfsd @file may be %NULL and
255 * only @dentry is set. This can only happen when the filesystem
256 * implements the export_operations API.
258 int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)
260 return vfs_fsync_range(file, dentry, 0, LLONG_MAX, datasync);
262 EXPORT_SYMBOL(vfs_fsync);
264 static int do_fsync(unsigned int fd, int datasync)
271 ret = vfs_fsync(file, file->f_path.dentry, datasync);
277 SYSCALL_DEFINE1(fsync, unsigned int, fd)
279 return do_fsync(fd, 0);
282 SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
284 return do_fsync(fd, 1);
288 * generic_write_sync - perform syncing after a write if file / inode is sync
289 * @file: file to which the write happened
290 * @pos: offset where the write started
291 * @count: length of the write
293 * This is just a simple wrapper about our general syncing function.
295 int generic_write_sync(struct file *file, loff_t pos, loff_t count)
297 if (!(file->f_flags & O_SYNC) && !IS_SYNC(file->f_mapping->host))
299 return vfs_fsync_range(file, file->f_path.dentry, pos,
302 EXPORT_SYMBOL(generic_write_sync);
305 * sys_sync_file_range() permits finely controlled syncing over a segment of
306 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
307 * zero then sys_sync_file_range() will operate from offset out to EOF.
311 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
312 * before performing the write.
314 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
315 * range which are not presently under writeback. Note that this may block for
316 * significant periods due to exhaustion of disk request structures.
318 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
319 * after performing the write.
321 * Useful combinations of the flag bits are:
323 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
324 * in the range which were dirty on entry to sys_sync_file_range() are placed
325 * under writeout. This is a start-write-for-data-integrity operation.
327 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
328 * are not presently under writeout. This is an asynchronous flush-to-disk
329 * operation. Not suitable for data integrity operations.
331 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
332 * completion of writeout of all pages in the range. This will be used after an
333 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
334 * for that operation to complete and to return the result.
336 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
337 * a traditional sync() operation. This is a write-for-data-integrity operation
338 * which will ensure that all pages in the range which were dirty on entry to
339 * sys_sync_file_range() are committed to disk.
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.
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.
351 SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes,
356 loff_t endbyte; /* inclusive */
361 if (flags & ~VALID_FLAGS)
364 endbyte = offset + nbytes;
368 if ((s64)endbyte < 0)
370 if (endbyte < offset)
373 if (sizeof(pgoff_t) == 4) {
374 if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
376 * The range starts outside a 32 bit machine's
377 * pagecache addressing capabilities. Let it "succeed"
382 if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
393 endbyte--; /* inclusive */
396 file = fget_light(fd, &fput_needed);
400 i_mode = file->f_path.dentry->d_inode->i_mode;
402 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
406 ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags);
408 fput_light(file, fput_needed);
412 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
413 asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes,
416 return SYSC_sync_file_range((int) fd, offset, nbytes,
417 (unsigned int) flags);
419 SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range);
422 /* It would be nice if people remember that not all the world's an i386
423 when they introduce new system calls */
424 SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags,
425 loff_t offset, loff_t nbytes)
427 return sys_sync_file_range(fd, offset, nbytes, flags);
429 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
430 asmlinkage long SyS_sync_file_range2(long fd, long flags,
431 loff_t offset, loff_t nbytes)
433 return SYSC_sync_file_range2((int) fd, (unsigned int) flags,
436 SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2);
440 * `endbyte' is inclusive
442 int do_sync_mapping_range(struct address_space *mapping, loff_t offset,
443 loff_t endbyte, unsigned int flags)
453 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
454 ret = wait_on_page_writeback_range(mapping,
455 offset >> PAGE_CACHE_SHIFT,
456 endbyte >> PAGE_CACHE_SHIFT);
461 if (flags & SYNC_FILE_RANGE_WRITE) {
462 ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
468 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) {
469 ret = wait_on_page_writeback_range(mapping,
470 offset >> PAGE_CACHE_SHIFT,
471 endbyte >> PAGE_CACHE_SHIFT);
476 EXPORT_SYMBOL_GPL(do_sync_mapping_range);