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/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>
16
17#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
18			SYNC_FILE_RANGE_WAIT_AFTER)
19
20/*
21 * sync everything.  Start out by waking pdflush, because that writes back
22 * all queues in parallel.
23 */
24static void do_sync(unsigned long wait)
25{
26	wakeup_pdflush(0);
27	sync_inodes(0);		/* All mappings, inodes and their blockdevs */
28	DQUOT_SYNC(NULL);
29	sync_supers();		/* Write the superblocks */
30	sync_filesystems(0);	/* Start syncing the filesystems */
31	sync_filesystems(wait);	/* Waitingly sync the filesystems */
32	sync_inodes(wait);	/* Mappings, inodes and blockdevs, again. */
33	if (!wait)
34		printk("Emergency Sync complete\n");
35	if (unlikely(laptop_mode))
36		laptop_sync_completion();
37}
38
39asmlinkage long sys_sync(void)
40{
41	do_sync(1);
42	return 0;
43}
44
45void emergency_sync(void)
46{
47	pdflush_operation(do_sync, 0);
48}
49
50/*
51 * Generic function to fsync a file.
52 *
53 * filp may be NULL if called via the msync of a vma.
54 */
55int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
56{
57	struct inode * inode = dentry->d_inode;
58	struct super_block * sb;
59	int ret, err;
60
61	/* sync the inode to buffers */
62	ret = write_inode_now(inode, 0);
63
64	/* sync the superblock to buffers */
65	sb = inode->i_sb;
66	lock_super(sb);
67	if (sb->s_op->write_super)
68		sb->s_op->write_super(sb);
69	unlock_super(sb);
70
71	/* .. finally sync the buffers to disk */
72	err = sync_blockdev(sb->s_bdev);
73	if (!ret)
74		ret = err;
75	return ret;
76}
77
78long do_fsync(struct file *file, int datasync)
79{
80	int ret;
81	int err;
82	struct address_space *mapping = file->f_mapping;
83
84	if (!file->f_op || !file->f_op->fsync) {
85		/* Why?  We can still call filemap_fdatawrite */
86		ret = -EINVAL;
87		goto out;
88	}
89
90	ret = filemap_fdatawrite(mapping);
91
92	/*
93	 * We need to protect against concurrent writers, which could cause
94	 * livelocks in fsync_buffers_list().
95	 */
96	mutex_lock(&mapping->host->i_mutex);
97	err = file->f_op->fsync(file, file->f_path.dentry, datasync);
98	if (!ret)
99		ret = err;
100	mutex_unlock(&mapping->host->i_mutex);
101	err = filemap_fdatawait(mapping);
102	if (!ret)
103		ret = err;
104out:
105	return ret;
106}
107
108static long __do_fsync(unsigned int fd, int datasync)
109{
110	struct file *file;
111	int ret = -EBADF;
112
113	file = fget(fd);
114	if (file) {
115		ret = do_fsync(file, datasync);
116		fput(file);
117	}
118	return ret;
119}
120
121asmlinkage long sys_fsync(unsigned int fd)
122{
123	return __do_fsync(fd, 0);
124}
125
126asmlinkage long sys_fdatasync(unsigned int fd)
127{
128	return __do_fsync(fd, 1);
129}
130
131/*
132 * sys_sync_file_range() permits finely controlled syncing over a segment of
133 * a file in the range offset .. (offset+nbytes-1) inclusive.  If nbytes is
134 * zero then sys_sync_file_range() will operate from offset out to EOF.
135 *
136 * The flag bits are:
137 *
138 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
139 * before performing the write.
140 *
141 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
142 * range which are not presently under writeback.
143 *
144 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
145 * after performing the write.
146 *
147 * Useful combinations of the flag bits are:
148 *
149 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
150 * in the range which were dirty on entry to sys_sync_file_range() are placed
151 * under writeout.  This is a start-write-for-data-integrity operation.
152 *
153 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
154 * are not presently under writeout.  This is an asynchronous flush-to-disk
155 * operation.  Not suitable for data integrity operations.
156 *
157 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
158 * completion of writeout of all pages in the range.  This will be used after an
159 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
160 * for that operation to complete and to return the result.
161 *
162 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
163 * a traditional sync() operation.  This is a write-for-data-integrity operation
164 * which will ensure that all pages in the range which were dirty on entry to
165 * sys_sync_file_range() are committed to disk.
166 *
167 *
168 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
169 * I/O errors or ENOSPC conditions and will return those to the caller, after
170 * clearing the EIO and ENOSPC flags in the address_space.
171 *
172 * It should be noted that none of these operations write out the file's
173 * metadata.  So unless the application is strictly performing overwrites of
174 * already-instantiated disk blocks, there are no guarantees here that the data
175 * will be available after a crash.
176 */
177asmlinkage long sys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
178					unsigned int flags)
179{
180	int ret;
181	struct file *file;
182	loff_t endbyte;			/* inclusive */
183	int fput_needed;
184	umode_t i_mode;
185
186	ret = -EINVAL;
187	if (flags & ~VALID_FLAGS)
188		goto out;
189
190	endbyte = offset + nbytes;
191
192	if ((s64)offset < 0)
193		goto out;
194	if ((s64)endbyte < 0)
195		goto out;
196	if (endbyte < offset)
197		goto out;
198
199	if (sizeof(pgoff_t) == 4) {
200		if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
201			/*
202			 * The range starts outside a 32 bit machine's
203			 * pagecache addressing capabilities.  Let it "succeed"
204			 */
205			ret = 0;
206			goto out;
207		}
208		if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
209			/*
210			 * Out to EOF
211			 */
212			nbytes = 0;
213		}
214	}
215
216	if (nbytes == 0)
217		endbyte = LLONG_MAX;
218	else
219		endbyte--;		/* inclusive */
220
221	ret = -EBADF;
222	file = fget_light(fd, &fput_needed);
223	if (!file)
224		goto out;
225
226	i_mode = file->f_path.dentry->d_inode->i_mode;
227	ret = -ESPIPE;
228	if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
229			!S_ISLNK(i_mode))
230		goto out_put;
231
232	ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags);
233out_put:
234	fput_light(file, fput_needed);
235out:
236	return ret;
237}
238
239/* It would be nice if people remember that not all the world's an i386
240   when they introduce new system calls */
241asmlinkage long sys_sync_file_range2(int fd, unsigned int flags,
242				     loff_t offset, loff_t nbytes)
243{
244	return sys_sync_file_range(fd, offset, nbytes, flags);
245}
246
247/*
248 * `endbyte' is inclusive
249 */
250int do_sync_mapping_range(struct address_space *mapping, loff_t offset,
251			  loff_t endbyte, unsigned int flags)
252{
253	int ret;
254
255	if (!mapping) {
256		ret = -EINVAL;
257		goto out;
258	}
259
260	ret = 0;
261	if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
262		ret = wait_on_page_writeback_range(mapping,
263					offset >> PAGE_CACHE_SHIFT,
264					endbyte >> PAGE_CACHE_SHIFT);
265		if (ret < 0)
266			goto out;
267	}
268
269	if (flags & SYNC_FILE_RANGE_WRITE) {
270		ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
271						WB_SYNC_NONE);
272		if (ret < 0)
273			goto out;
274	}
275
276	if (flags & SYNC_FILE_RANGE_WAIT_AFTER) {
277		ret = wait_on_page_writeback_range(mapping,
278					offset >> PAGE_CACHE_SHIFT,
279					endbyte >> PAGE_CACHE_SHIFT);
280	}
281out:
282	return ret;
283}
284EXPORT_SYMBOL_GPL(do_sync_mapping_range);
285