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 sync_inodes_sb(sb, 0)
23 * just dirties buffers with inodes so we have to submit IO for these buffers
24 * via __sync_blockdev(). This also speeds up the wait == 1 case since in that
25 * case write_inode() functions do sync_dirty_buffer() and thus effectively
26 * write one block at a time.
28 static int __sync_filesystem(struct super_block *sb, int wait)
30 /* Avoid doing twice syncing and cache pruning for quota sync */
32 writeout_quota_sb(sb, -1);
34 sync_quota_sb(sb, -1);
35 sync_inodes_sb(sb, wait);
36 if (sb->s_dirt && sb->s_op->write_super)
37 sb->s_op->write_super(sb);
38 if (sb->s_op->sync_fs)
39 sb->s_op->sync_fs(sb, wait);
40 return __sync_blockdev(sb->s_bdev, wait);
44 * Write out and wait upon all dirty data associated with this
45 * superblock. Filesystem data as well as the underlying block
46 * device. Takes the superblock lock.
48 int sync_filesystem(struct super_block *sb)
53 * We need to be protected against the filesystem going from
54 * r/o to r/w or vice versa.
56 WARN_ON(!rwsem_is_locked(&sb->s_umount));
59 * No point in syncing out anything if the filesystem is read-only.
61 if (sb->s_flags & MS_RDONLY)
64 ret = __sync_filesystem(sb, 0);
67 return __sync_filesystem(sb, 1);
69 EXPORT_SYMBOL_GPL(sync_filesystem);
72 * Sync all the data for all the filesystems (called by sys_sync() and
75 * This operation is careful to avoid the livelock which could easily happen
76 * if two or more filesystems are being continuously dirtied. s_need_sync
77 * is used only here. We set it against all filesystems and then clear it as
78 * we sync them. So redirtied filesystems are skipped.
80 * But if process A is currently running sync_filesystems and then process B
81 * calls sync_filesystems as well, process B will set all the s_need_sync
82 * flags again, which will cause process A to resync everything. Fix that with
85 static void sync_filesystems(int wait)
87 struct super_block *sb;
88 static DEFINE_MUTEX(mutex);
90 mutex_lock(&mutex); /* Could be down_interruptible */
92 list_for_each_entry(sb, &super_blocks, s_list)
96 list_for_each_entry(sb, &super_blocks, s_list) {
101 spin_unlock(&sb_lock);
103 down_read(&sb->s_umount);
104 if (!(sb->s_flags & MS_RDONLY) && sb->s_root)
105 __sync_filesystem(sb, wait);
106 up_read(&sb->s_umount);
108 /* restart only when sb is no longer on the list */
110 if (__put_super_and_need_restart(sb))
113 spin_unlock(&sb_lock);
114 mutex_unlock(&mutex);
117 SYSCALL_DEFINE0(sync)
121 if (unlikely(laptop_mode))
122 laptop_sync_completion();
126 static void do_sync_work(struct work_struct *work)
129 * Sync twice to reduce the possibility we skipped some inodes / pages
130 * because they were temporarily locked
134 printk("Emergency Sync complete\n");
138 void emergency_sync(void)
140 struct work_struct *work;
142 work = kmalloc(sizeof(*work), GFP_ATOMIC);
144 INIT_WORK(work, do_sync_work);
150 * Generic function to fsync a file.
152 * filp may be NULL if called via the msync of a vma.
154 int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
156 struct inode * inode = dentry->d_inode;
157 struct super_block * sb;
160 /* sync the inode to buffers */
161 ret = write_inode_now(inode, 0);
163 /* sync the superblock to buffers */
165 if (sb->s_dirt && sb->s_op->write_super)
166 sb->s_op->write_super(sb);
168 /* .. finally sync the buffers to disk */
169 err = sync_blockdev(sb->s_bdev);
176 * vfs_fsync - perform a fsync or fdatasync on a file
177 * @file: file to sync
178 * @dentry: dentry of @file
179 * @data: only perform a fdatasync operation
181 * Write back data and metadata for @file to disk. If @datasync is
182 * set only metadata needed to access modified file data is written.
184 * In case this function is called from nfsd @file may be %NULL and
185 * only @dentry is set. This can only happen when the filesystem
186 * implements the export_operations API.
188 int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)
190 const struct file_operations *fop;
191 struct address_space *mapping;
195 * Get mapping and operations from the file in case we have
196 * as file, or get the default values for them in case we
197 * don't have a struct file available. Damn nfsd..
200 mapping = file->f_mapping;
203 mapping = dentry->d_inode->i_mapping;
204 fop = dentry->d_inode->i_fop;
207 if (!fop || !fop->fsync) {
212 ret = filemap_fdatawrite(mapping);
215 * We need to protect against concurrent writers, which could cause
216 * livelocks in fsync_buffers_list().
218 mutex_lock(&mapping->host->i_mutex);
219 err = fop->fsync(file, dentry, datasync);
222 mutex_unlock(&mapping->host->i_mutex);
223 err = filemap_fdatawait(mapping);
229 EXPORT_SYMBOL(vfs_fsync);
231 static int do_fsync(unsigned int fd, int datasync)
238 ret = vfs_fsync(file, file->f_path.dentry, datasync);
244 SYSCALL_DEFINE1(fsync, unsigned int, fd)
246 return do_fsync(fd, 0);
249 SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
251 return do_fsync(fd, 1);
255 * sys_sync_file_range() permits finely controlled syncing over a segment of
256 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
257 * zero then sys_sync_file_range() will operate from offset out to EOF.
261 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
262 * before performing the write.
264 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
265 * range which are not presently under writeback. Note that this may block for
266 * significant periods due to exhaustion of disk request structures.
268 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
269 * after performing the write.
271 * Useful combinations of the flag bits are:
273 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
274 * in the range which were dirty on entry to sys_sync_file_range() are placed
275 * under writeout. This is a start-write-for-data-integrity operation.
277 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
278 * are not presently under writeout. This is an asynchronous flush-to-disk
279 * operation. Not suitable for data integrity operations.
281 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
282 * completion of writeout of all pages in the range. This will be used after an
283 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
284 * for that operation to complete and to return the result.
286 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
287 * a traditional sync() operation. This is a write-for-data-integrity operation
288 * which will ensure that all pages in the range which were dirty on entry to
289 * sys_sync_file_range() are committed to disk.
292 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
293 * I/O errors or ENOSPC conditions and will return those to the caller, after
294 * clearing the EIO and ENOSPC flags in the address_space.
296 * It should be noted that none of these operations write out the file's
297 * metadata. So unless the application is strictly performing overwrites of
298 * already-instantiated disk blocks, there are no guarantees here that the data
299 * will be available after a crash.
301 SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes,
306 loff_t endbyte; /* inclusive */
311 if (flags & ~VALID_FLAGS)
314 endbyte = offset + nbytes;
318 if ((s64)endbyte < 0)
320 if (endbyte < offset)
323 if (sizeof(pgoff_t) == 4) {
324 if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
326 * The range starts outside a 32 bit machine's
327 * pagecache addressing capabilities. Let it "succeed"
332 if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
343 endbyte--; /* inclusive */
346 file = fget_light(fd, &fput_needed);
350 i_mode = file->f_path.dentry->d_inode->i_mode;
352 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
356 ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags);
358 fput_light(file, fput_needed);
362 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
363 asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes,
366 return SYSC_sync_file_range((int) fd, offset, nbytes,
367 (unsigned int) flags);
369 SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range);
372 /* It would be nice if people remember that not all the world's an i386
373 when they introduce new system calls */
374 SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags,
375 loff_t offset, loff_t nbytes)
377 return sys_sync_file_range(fd, offset, nbytes, flags);
379 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
380 asmlinkage long SyS_sync_file_range2(long fd, long flags,
381 loff_t offset, loff_t nbytes)
383 return SYSC_sync_file_range2((int) fd, (unsigned int) flags,
386 SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2);
390 * `endbyte' is inclusive
392 int do_sync_mapping_range(struct address_space *mapping, loff_t offset,
393 loff_t endbyte, unsigned int flags)
403 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
404 ret = wait_on_page_writeback_range(mapping,
405 offset >> PAGE_CACHE_SHIFT,
406 endbyte >> PAGE_CACHE_SHIFT);
411 if (flags & SYNC_FILE_RANGE_WRITE) {
412 ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
418 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) {
419 ret = wait_on_page_writeback_range(mapping,
420 offset >> PAGE_CACHE_SHIFT,
421 endbyte >> PAGE_CACHE_SHIFT);
426 EXPORT_SYMBOL_GPL(do_sync_mapping_range);