1/*
2 * High-level sync()-related operations
3 */
4
5#include <linux/kernel.h>
6#include <linux/file.h>
7#include <linux/fs.h>
8#include <linux/slab.h>
9#include <linux/export.h>
10#include <linux/namei.h>
11#include <linux/sched.h>
12#include <linux/writeback.h>
13#include <linux/syscalls.h>
14#include <linux/linkage.h>
15#include <linux/pagemap.h>
16#include <linux/quotaops.h>
17#include <linux/backing-dev.h>
18#include "internal.h"
19
20#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
21			SYNC_FILE_RANGE_WAIT_AFTER)
22
23/*
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.
29 */
30static int __sync_filesystem(struct super_block *sb, int wait)
31{
32	if (wait)
33		sync_inodes_sb(sb);
34	else
35		writeback_inodes_sb(sb, WB_REASON_SYNC);
36
37	if (sb->s_op->sync_fs)
38		sb->s_op->sync_fs(sb, wait);
39	return __sync_blockdev(sb->s_bdev, wait);
40}
41
42/*
43 * Write out and wait upon all dirty data associated with this
44 * superblock.  Filesystem data as well as the underlying block
45 * device.  Takes the superblock lock.
46 */
47int sync_filesystem(struct super_block *sb)
48{
49	int ret;
50
51	/*
52	 * We need to be protected against the filesystem going from
53	 * r/o to r/w or vice versa.
54	 */
55	WARN_ON(!rwsem_is_locked(&sb->s_umount));
56
57	/*
58	 * No point in syncing out anything if the filesystem is read-only.
59	 */
60	if (sb->s_flags & MS_RDONLY)
61		return 0;
62
63	ret = __sync_filesystem(sb, 0);
64	if (ret < 0)
65		return ret;
66	return __sync_filesystem(sb, 1);
67}
68EXPORT_SYMBOL(sync_filesystem);
69
70static void sync_inodes_one_sb(struct super_block *sb, void *arg)
71{
72	if (!(sb->s_flags & MS_RDONLY))
73		sync_inodes_sb(sb);
74}
75
76static void sync_fs_one_sb(struct super_block *sb, void *arg)
77{
78	if (!(sb->s_flags & MS_RDONLY) && sb->s_op->sync_fs)
79		sb->s_op->sync_fs(sb, *(int *)arg);
80}
81
82static void fdatawrite_one_bdev(struct block_device *bdev, void *arg)
83{
84	filemap_fdatawrite(bdev->bd_inode->i_mapping);
85}
86
87static void fdatawait_one_bdev(struct block_device *bdev, void *arg)
88{
89	/*
90	 * We keep the error status of individual mapping so that
91	 * applications can catch the writeback error using fsync(2).
92	 * See filemap_fdatawait_keep_errors() for details.
93	 */
94	filemap_fdatawait_keep_errors(bdev->bd_inode->i_mapping);
95}
96
97/*
98 * Sync everything. We start by waking flusher threads so that most of
99 * writeback runs on all devices in parallel. Then we sync all inodes reliably
100 * which effectively also waits for all flusher threads to finish doing
101 * writeback. At this point all data is on disk so metadata should be stable
102 * and we tell filesystems to sync their metadata via ->sync_fs() calls.
103 * Finally, we writeout all block devices because some filesystems (e.g. ext2)
104 * just write metadata (such as inodes or bitmaps) to block device page cache
105 * and do not sync it on their own in ->sync_fs().
106 */
107SYSCALL_DEFINE0(sync)
108{
109	int nowait = 0, wait = 1;
110
111	wakeup_flusher_threads(0, WB_REASON_SYNC);
112	iterate_supers(sync_inodes_one_sb, NULL);
113	iterate_supers(sync_fs_one_sb, &nowait);
114	iterate_supers(sync_fs_one_sb, &wait);
115	iterate_bdevs(fdatawrite_one_bdev, NULL);
116	iterate_bdevs(fdatawait_one_bdev, NULL);
117	if (unlikely(laptop_mode))
118		laptop_sync_completion();
119	return 0;
120}
121
122static void do_sync_work(struct work_struct *work)
123{
124	int nowait = 0;
125
126	/*
127	 * Sync twice to reduce the possibility we skipped some inodes / pages
128	 * because they were temporarily locked
129	 */
130	iterate_supers(sync_inodes_one_sb, &nowait);
131	iterate_supers(sync_fs_one_sb, &nowait);
132	iterate_bdevs(fdatawrite_one_bdev, NULL);
133	iterate_supers(sync_inodes_one_sb, &nowait);
134	iterate_supers(sync_fs_one_sb, &nowait);
135	iterate_bdevs(fdatawrite_one_bdev, NULL);
136	printk("Emergency Sync complete\n");
137	kfree(work);
138}
139
140void emergency_sync(void)
141{
142	struct work_struct *work;
143
144	work = kmalloc(sizeof(*work), GFP_ATOMIC);
145	if (work) {
146		INIT_WORK(work, do_sync_work);
147		schedule_work(work);
148	}
149}
150
151/*
152 * sync a single super
153 */
154SYSCALL_DEFINE1(syncfs, int, fd)
155{
156	struct fd f = fdget(fd);
157	struct super_block *sb;
158	int ret;
159
160	if (!f.file)
161		return -EBADF;
162	sb = f.file->f_path.dentry->d_sb;
163
164	down_read(&sb->s_umount);
165	ret = sync_filesystem(sb);
166	up_read(&sb->s_umount);
167
168	fdput(f);
169	return ret;
170}
171
172/**
173 * vfs_fsync_range - helper to sync a range of data & metadata to disk
174 * @file:		file to sync
175 * @start:		offset in bytes of the beginning of data range to sync
176 * @end:		offset in bytes of the end of data range (inclusive)
177 * @datasync:		perform only datasync
178 *
179 * Write back data in range @start..@end and metadata for @file to disk.  If
180 * @datasync is set only metadata needed to access modified file data is
181 * written.
182 */
183int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync)
184{
185	struct inode *inode = file->f_mapping->host;
186
187	if (!file->f_op->fsync)
188		return -EINVAL;
189	if (!datasync && (inode->i_state & I_DIRTY_TIME)) {
190		spin_lock(&inode->i_lock);
191		inode->i_state &= ~I_DIRTY_TIME;
192		spin_unlock(&inode->i_lock);
193		mark_inode_dirty_sync(inode);
194	}
195	return file->f_op->fsync(file, start, end, datasync);
196}
197EXPORT_SYMBOL(vfs_fsync_range);
198
199/**
200 * vfs_fsync - perform a fsync or fdatasync on a file
201 * @file:		file to sync
202 * @datasync:		only perform a fdatasync operation
203 *
204 * Write back data and metadata for @file to disk.  If @datasync is
205 * set only metadata needed to access modified file data is written.
206 */
207int vfs_fsync(struct file *file, int datasync)
208{
209	return vfs_fsync_range(file, 0, LLONG_MAX, datasync);
210}
211EXPORT_SYMBOL(vfs_fsync);
212
213static int do_fsync(unsigned int fd, int datasync)
214{
215	struct fd f = fdget(fd);
216	int ret = -EBADF;
217
218	if (f.file) {
219		ret = vfs_fsync(f.file, datasync);
220		fdput(f);
221	}
222	return ret;
223}
224
225SYSCALL_DEFINE1(fsync, unsigned int, fd)
226{
227	return do_fsync(fd, 0);
228}
229
230SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
231{
232	return do_fsync(fd, 1);
233}
234
235/*
236 * sys_sync_file_range() permits finely controlled syncing over a segment of
237 * a file in the range offset .. (offset+nbytes-1) inclusive.  If nbytes is
238 * zero then sys_sync_file_range() will operate from offset out to EOF.
239 *
240 * The flag bits are:
241 *
242 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
243 * before performing the write.
244 *
245 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
246 * range which are not presently under writeback. Note that this may block for
247 * significant periods due to exhaustion of disk request structures.
248 *
249 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
250 * after performing the write.
251 *
252 * Useful combinations of the flag bits are:
253 *
254 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
255 * in the range which were dirty on entry to sys_sync_file_range() are placed
256 * under writeout.  This is a start-write-for-data-integrity operation.
257 *
258 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
259 * are not presently under writeout.  This is an asynchronous flush-to-disk
260 * operation.  Not suitable for data integrity operations.
261 *
262 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
263 * completion of writeout of all pages in the range.  This will be used after an
264 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
265 * for that operation to complete and to return the result.
266 *
267 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
268 * a traditional sync() operation.  This is a write-for-data-integrity operation
269 * which will ensure that all pages in the range which were dirty on entry to
270 * sys_sync_file_range() are committed to disk.
271 *
272 *
273 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
274 * I/O errors or ENOSPC conditions and will return those to the caller, after
275 * clearing the EIO and ENOSPC flags in the address_space.
276 *
277 * It should be noted that none of these operations write out the file's
278 * metadata.  So unless the application is strictly performing overwrites of
279 * already-instantiated disk blocks, there are no guarantees here that the data
280 * will be available after a crash.
281 */
282SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes,
283				unsigned int, flags)
284{
285	int ret;
286	struct fd f;
287	struct address_space *mapping;
288	loff_t endbyte;			/* inclusive */
289	umode_t i_mode;
290
291	ret = -EINVAL;
292	if (flags & ~VALID_FLAGS)
293		goto out;
294
295	endbyte = offset + nbytes;
296
297	if ((s64)offset < 0)
298		goto out;
299	if ((s64)endbyte < 0)
300		goto out;
301	if (endbyte < offset)
302		goto out;
303
304	if (sizeof(pgoff_t) == 4) {
305		if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
306			/*
307			 * The range starts outside a 32 bit machine's
308			 * pagecache addressing capabilities.  Let it "succeed"
309			 */
310			ret = 0;
311			goto out;
312		}
313		if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
314			/*
315			 * Out to EOF
316			 */
317			nbytes = 0;
318		}
319	}
320
321	if (nbytes == 0)
322		endbyte = LLONG_MAX;
323	else
324		endbyte--;		/* inclusive */
325
326	ret = -EBADF;
327	f = fdget(fd);
328	if (!f.file)
329		goto out;
330
331	i_mode = file_inode(f.file)->i_mode;
332	ret = -ESPIPE;
333	if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
334			!S_ISLNK(i_mode))
335		goto out_put;
336
337	mapping = f.file->f_mapping;
338	if (!mapping) {
339		ret = -EINVAL;
340		goto out_put;
341	}
342
343	ret = 0;
344	if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
345		ret = filemap_fdatawait_range(mapping, offset, endbyte);
346		if (ret < 0)
347			goto out_put;
348	}
349
350	if (flags & SYNC_FILE_RANGE_WRITE) {
351		ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
352						 WB_SYNC_NONE);
353		if (ret < 0)
354			goto out_put;
355	}
356
357	if (flags & SYNC_FILE_RANGE_WAIT_AFTER)
358		ret = filemap_fdatawait_range(mapping, offset, endbyte);
359
360out_put:
361	fdput(f);
362out:
363	return ret;
364}
365
366/* It would be nice if people remember that not all the world's an i386
367   when they introduce new system calls */
368SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags,
369				 loff_t, offset, loff_t, nbytes)
370{
371	return sys_sync_file_range(fd, offset, nbytes, flags);
372}
373