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 */
__sync_filesystem(struct super_block * sb,int wait)30 static 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 */
sync_filesystem(struct super_block * sb)47 int 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 }
68 EXPORT_SYMBOL(sync_filesystem);
69
sync_inodes_one_sb(struct super_block * sb,void * arg)70 static 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
sync_fs_one_sb(struct super_block * sb,void * arg)76 static 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
fdatawrite_one_bdev(struct block_device * bdev,void * arg)82 static void fdatawrite_one_bdev(struct block_device *bdev, void *arg)
83 {
84 filemap_fdatawrite(bdev->bd_inode->i_mapping);
85 }
86
fdatawait_one_bdev(struct block_device * bdev,void * arg)87 static 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 */
SYSCALL_DEFINE0(sync)107 SYSCALL_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
do_sync_work(struct work_struct * work)122 static 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
emergency_sync(void)140 void 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 */
SYSCALL_DEFINE1(syncfs,int,fd)154 SYSCALL_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 */
vfs_fsync_range(struct file * file,loff_t start,loff_t end,int datasync)183 int 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 }
197 EXPORT_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 */
vfs_fsync(struct file * file,int datasync)207 int vfs_fsync(struct file *file, int datasync)
208 {
209 return vfs_fsync_range(file, 0, LLONG_MAX, datasync);
210 }
211 EXPORT_SYMBOL(vfs_fsync);
212
do_fsync(unsigned int fd,int datasync)213 static 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 inc_syscfs(current);
222 }
223 return ret;
224 }
225
SYSCALL_DEFINE1(fsync,unsigned int,fd)226 SYSCALL_DEFINE1(fsync, unsigned int, fd)
227 {
228 return do_fsync(fd, 0);
229 }
230
SYSCALL_DEFINE1(fdatasync,unsigned int,fd)231 SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
232 {
233 return do_fsync(fd, 1);
234 }
235
236 /*
237 * sys_sync_file_range() permits finely controlled syncing over a segment of
238 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
239 * zero then sys_sync_file_range() will operate from offset out to EOF.
240 *
241 * The flag bits are:
242 *
243 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
244 * before performing the write.
245 *
246 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
247 * range which are not presently under writeback. Note that this may block for
248 * significant periods due to exhaustion of disk request structures.
249 *
250 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
251 * after performing the write.
252 *
253 * Useful combinations of the flag bits are:
254 *
255 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
256 * in the range which were dirty on entry to sys_sync_file_range() are placed
257 * under writeout. This is a start-write-for-data-integrity operation.
258 *
259 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
260 * are not presently under writeout. This is an asynchronous flush-to-disk
261 * operation. Not suitable for data integrity operations.
262 *
263 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
264 * completion of writeout of all pages in the range. This will be used after an
265 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
266 * for that operation to complete and to return the result.
267 *
268 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
269 * a traditional sync() operation. This is a write-for-data-integrity operation
270 * which will ensure that all pages in the range which were dirty on entry to
271 * sys_sync_file_range() are committed to disk.
272 *
273 *
274 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
275 * I/O errors or ENOSPC conditions and will return those to the caller, after
276 * clearing the EIO and ENOSPC flags in the address_space.
277 *
278 * It should be noted that none of these operations write out the file's
279 * metadata. So unless the application is strictly performing overwrites of
280 * already-instantiated disk blocks, there are no guarantees here that the data
281 * will be available after a crash.
282 */
SYSCALL_DEFINE4(sync_file_range,int,fd,loff_t,offset,loff_t,nbytes,unsigned int,flags)283 SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes,
284 unsigned int, flags)
285 {
286 int ret;
287 struct fd f;
288 struct address_space *mapping;
289 loff_t endbyte; /* inclusive */
290 umode_t i_mode;
291
292 ret = -EINVAL;
293 if (flags & ~VALID_FLAGS)
294 goto out;
295
296 endbyte = offset + nbytes;
297
298 if ((s64)offset < 0)
299 goto out;
300 if ((s64)endbyte < 0)
301 goto out;
302 if (endbyte < offset)
303 goto out;
304
305 if (sizeof(pgoff_t) == 4) {
306 if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
307 /*
308 * The range starts outside a 32 bit machine's
309 * pagecache addressing capabilities. Let it "succeed"
310 */
311 ret = 0;
312 goto out;
313 }
314 if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
315 /*
316 * Out to EOF
317 */
318 nbytes = 0;
319 }
320 }
321
322 if (nbytes == 0)
323 endbyte = LLONG_MAX;
324 else
325 endbyte--; /* inclusive */
326
327 ret = -EBADF;
328 f = fdget(fd);
329 if (!f.file)
330 goto out;
331
332 i_mode = file_inode(f.file)->i_mode;
333 ret = -ESPIPE;
334 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
335 !S_ISLNK(i_mode))
336 goto out_put;
337
338 mapping = f.file->f_mapping;
339 if (!mapping) {
340 ret = -EINVAL;
341 goto out_put;
342 }
343
344 ret = 0;
345 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
346 ret = filemap_fdatawait_range(mapping, offset, endbyte);
347 if (ret < 0)
348 goto out_put;
349 }
350
351 if (flags & SYNC_FILE_RANGE_WRITE) {
352 ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
353 WB_SYNC_NONE);
354 if (ret < 0)
355 goto out_put;
356 }
357
358 if (flags & SYNC_FILE_RANGE_WAIT_AFTER)
359 ret = filemap_fdatawait_range(mapping, offset, endbyte);
360
361 out_put:
362 fdput(f);
363 out:
364 return ret;
365 }
366
367 /* It would be nice if people remember that not all the world's an i386
368 when they introduce new system calls */
SYSCALL_DEFINE4(sync_file_range2,int,fd,unsigned int,flags,loff_t,offset,loff_t,nbytes)369 SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags,
370 loff_t, offset, loff_t, nbytes)
371 {
372 return sys_sync_file_range(fd, offset, nbytes, flags);
373 }
374