2 * High-level sync()-related operations
5 #include <linux/kernel.h>
6 #include <linux/file.h>
8 #include <linux/slab.h>
9 #include <linux/module.h>
10 #include <linux/sched.h>
11 #include <linux/writeback.h>
12 #include <linux/syscalls.h>
13 #include <linux/linkage.h>
14 #include <linux/pagemap.h>
15 #include <linux/quotaops.h>
16 #include <linux/buffer_head.h>
17 #include <linux/backing-dev.h>
20 #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
21 SYNC_FILE_RANGE_WAIT_AFTER)
24 * Do the filesystem syncing work. For simple filesystems
25 * writeback_inodes_sb(sb) just dirties buffers with inodes so we have to
26 * submit IO for these buffers via __sync_blockdev(). This also speeds up the
27 * wait == 1 case since in that case write_inode() functions do
28 * sync_dirty_buffer() and thus effectively write one block at a time.
30 static int __sync_filesystem(struct super_block *sb, int wait)
33 * This should be safe, as we require bdi backing to actually
34 * write out data in the first place
36 if (!sb->s_bdi || sb->s_bdi == &noop_backing_dev_info)
39 if (sb->s_qcop && sb->s_qcop->quota_sync)
40 sb->s_qcop->quota_sync(sb, -1, wait);
45 writeback_inodes_sb_locked(sb);
47 if (sb->s_op->sync_fs)
48 sb->s_op->sync_fs(sb, wait);
49 return __sync_blockdev(sb->s_bdev, wait);
53 * Write out and wait upon all dirty data associated with this
54 * superblock. Filesystem data as well as the underlying block
55 * device. Takes the superblock lock.
57 int sync_filesystem(struct super_block *sb)
62 * We need to be protected against the filesystem going from
63 * r/o to r/w or vice versa.
65 WARN_ON(!rwsem_is_locked(&sb->s_umount));
68 * No point in syncing out anything if the filesystem is read-only.
70 if (sb->s_flags & MS_RDONLY)
73 ret = __sync_filesystem(sb, 0);
76 return __sync_filesystem(sb, 1);
78 EXPORT_SYMBOL_GPL(sync_filesystem);
81 * Sync all the data for all the filesystems (called by sys_sync() and
84 * This operation is careful to avoid the livelock which could easily happen
85 * if two or more filesystems are being continuously dirtied. s_need_sync
86 * is used only here. We set it against all filesystems and then clear it as
87 * we sync them. So redirtied filesystems are skipped.
89 * But if process A is currently running sync_filesystems and then process B
90 * calls sync_filesystems as well, process B will set all the s_need_sync
91 * flags again, which will cause process A to resync everything. Fix that with
94 static void sync_filesystems(int wait)
96 struct super_block *sb;
97 static DEFINE_MUTEX(mutex);
99 mutex_lock(&mutex); /* Could be down_interruptible */
101 list_for_each_entry(sb, &super_blocks, s_list)
105 list_for_each_entry(sb, &super_blocks, s_list) {
106 if (!sb->s_need_sync)
110 spin_unlock(&sb_lock);
112 down_read(&sb->s_umount);
113 if (!(sb->s_flags & MS_RDONLY) && sb->s_root && sb->s_bdi)
114 __sync_filesystem(sb, wait);
115 up_read(&sb->s_umount);
117 /* restart only when sb is no longer on the list */
119 if (__put_super_and_need_restart(sb))
122 spin_unlock(&sb_lock);
123 mutex_unlock(&mutex);
127 * sync everything. Start out by waking pdflush, because that writes back
128 * all queues in parallel.
130 SYSCALL_DEFINE0(sync)
132 wakeup_flusher_threads(0);
135 if (unlikely(laptop_mode))
136 laptop_sync_completion();
140 static void do_sync_work(struct work_struct *work)
143 * Sync twice to reduce the possibility we skipped some inodes / pages
144 * because they were temporarily locked
148 printk("Emergency Sync complete\n");
152 void emergency_sync(void)
154 struct work_struct *work;
156 work = kmalloc(sizeof(*work), GFP_ATOMIC);
158 INIT_WORK(work, do_sync_work);
164 * Generic function to fsync a file.
166 * filp may be NULL if called via the msync of a vma.
168 int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
170 struct inode * inode = dentry->d_inode;
171 struct super_block * sb;
174 /* sync the inode to buffers */
175 ret = write_inode_now(inode, 0);
177 /* sync the superblock to buffers */
179 if (sb->s_dirt && sb->s_op->write_super)
180 sb->s_op->write_super(sb);
182 /* .. finally sync the buffers to disk */
183 err = sync_blockdev(sb->s_bdev);
188 EXPORT_SYMBOL(file_fsync);
191 * vfs_fsync_range - helper to sync a range of data & metadata to disk
192 * @file: file to sync
193 * @dentry: dentry of @file
194 * @start: offset in bytes of the beginning of data range to sync
195 * @end: offset in bytes of the end of data range (inclusive)
196 * @datasync: perform only datasync
198 * Write back data in range @start..@end and metadata for @file to disk. If
199 * @datasync is set only metadata needed to access modified file data is
202 * In case this function is called from nfsd @file may be %NULL and
203 * only @dentry is set. This can only happen when the filesystem
204 * implements the export_operations API.
206 int vfs_fsync_range(struct file *file, struct dentry *dentry, loff_t start,
207 loff_t end, int datasync)
209 const struct file_operations *fop;
210 struct address_space *mapping;
214 * Get mapping and operations from the file in case we have
215 * as file, or get the default values for them in case we
216 * don't have a struct file available. Damn nfsd..
219 mapping = file->f_mapping;
222 mapping = dentry->d_inode->i_mapping;
223 fop = dentry->d_inode->i_fop;
226 if (!fop || !fop->fsync) {
231 ret = filemap_write_and_wait_range(mapping, start, end);
234 * We need to protect against concurrent writers, which could cause
235 * livelocks in fsync_buffers_list().
237 mutex_lock(&mapping->host->i_mutex);
238 err = fop->fsync(file, dentry, datasync);
241 mutex_unlock(&mapping->host->i_mutex);
246 EXPORT_SYMBOL(vfs_fsync_range);
249 * vfs_fsync - perform a fsync or fdatasync on a file
250 * @file: file to sync
251 * @dentry: dentry of @file
252 * @datasync: only perform a fdatasync operation
254 * Write back data and metadata for @file to disk. If @datasync is
255 * set only metadata needed to access modified file data is written.
257 * In case this function is called from nfsd @file may be %NULL and
258 * only @dentry is set. This can only happen when the filesystem
259 * implements the export_operations API.
261 int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)
263 return vfs_fsync_range(file, dentry, 0, LLONG_MAX, datasync);
265 EXPORT_SYMBOL(vfs_fsync);
267 static int do_fsync(unsigned int fd, int datasync)
274 ret = vfs_fsync(file, file->f_path.dentry, datasync);
280 SYSCALL_DEFINE1(fsync, unsigned int, fd)
282 return do_fsync(fd, 0);
285 SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
287 return do_fsync(fd, 1);
291 * generic_write_sync - perform syncing after a write if file / inode is sync
292 * @file: file to which the write happened
293 * @pos: offset where the write started
294 * @count: length of the write
296 * This is just a simple wrapper about our general syncing function.
298 int generic_write_sync(struct file *file, loff_t pos, loff_t count)
300 if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
302 return vfs_fsync_range(file, file->f_path.dentry, pos,
304 (file->f_flags & __O_SYNC) ? 0 : 1);
306 EXPORT_SYMBOL(generic_write_sync);
309 * sys_sync_file_range() permits finely controlled syncing over a segment of
310 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
311 * zero then sys_sync_file_range() will operate from offset out to EOF.
315 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
316 * before performing the write.
318 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
319 * range which are not presently under writeback. Note that this may block for
320 * significant periods due to exhaustion of disk request structures.
322 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
323 * after performing the write.
325 * Useful combinations of the flag bits are:
327 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
328 * in the range which were dirty on entry to sys_sync_file_range() are placed
329 * under writeout. This is a start-write-for-data-integrity operation.
331 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
332 * are not presently under writeout. This is an asynchronous flush-to-disk
333 * operation. Not suitable for data integrity operations.
335 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
336 * completion of writeout of all pages in the range. This will be used after an
337 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
338 * for that operation to complete and to return the result.
340 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
341 * a traditional sync() operation. This is a write-for-data-integrity operation
342 * which will ensure that all pages in the range which were dirty on entry to
343 * sys_sync_file_range() are committed to disk.
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.
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.
355 SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes,
360 struct address_space *mapping;
361 loff_t endbyte; /* inclusive */
366 if (flags & ~VALID_FLAGS)
369 endbyte = offset + nbytes;
373 if ((s64)endbyte < 0)
375 if (endbyte < offset)
378 if (sizeof(pgoff_t) == 4) {
379 if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
381 * The range starts outside a 32 bit machine's
382 * pagecache addressing capabilities. Let it "succeed"
387 if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
398 endbyte--; /* inclusive */
401 file = fget_light(fd, &fput_needed);
405 i_mode = file->f_path.dentry->d_inode->i_mode;
407 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
411 mapping = file->f_mapping;
418 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
419 ret = filemap_fdatawait_range(mapping, offset, endbyte);
424 if (flags & SYNC_FILE_RANGE_WRITE) {
425 ret = filemap_fdatawrite_range(mapping, offset, endbyte);
430 if (flags & SYNC_FILE_RANGE_WAIT_AFTER)
431 ret = filemap_fdatawait_range(mapping, offset, endbyte);
434 fput_light(file, fput_needed);
438 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
439 asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes,
442 return SYSC_sync_file_range((int) fd, offset, nbytes,
443 (unsigned int) flags);
445 SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range);
448 /* It would be nice if people remember that not all the world's an i386
449 when they introduce new system calls */
450 SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags,
451 loff_t offset, loff_t nbytes)
453 return sys_sync_file_range(fd, offset, nbytes, flags);
455 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
456 asmlinkage long SyS_sync_file_range2(long fd, long flags,
457 loff_t offset, loff_t nbytes)
459 return SYSC_sync_file_range2((int) fd, (unsigned int) flags,
462 SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2);