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 filemap_fdatawait(bdev->bd_inode->i_mapping);
90 }
91
92 /*
93 * Sync everything. We start by waking flusher threads so that most of
94 * writeback runs on all devices in parallel. Then we sync all inodes reliably
95 * which effectively also waits for all flusher threads to finish doing
96 * writeback. At this point all data is on disk so metadata should be stable
97 * and we tell filesystems to sync their metadata via ->sync_fs() calls.
98 * Finally, we writeout all block devices because some filesystems (e.g. ext2)
99 * just write metadata (such as inodes or bitmaps) to block device page cache
100 * and do not sync it on their own in ->sync_fs().
101 */
SYSCALL_DEFINE0(sync)102 SYSCALL_DEFINE0(sync)
103 {
104 int nowait = 0, wait = 1;
105
106 wakeup_flusher_threads(0, WB_REASON_SYNC);
107 iterate_supers(sync_inodes_one_sb, NULL);
108 iterate_supers(sync_fs_one_sb, &nowait);
109 iterate_supers(sync_fs_one_sb, &wait);
110 iterate_bdevs(fdatawrite_one_bdev, NULL);
111 iterate_bdevs(fdatawait_one_bdev, NULL);
112 if (unlikely(laptop_mode))
113 laptop_sync_completion();
114 return 0;
115 }
116
do_sync_work(struct work_struct * work)117 static void do_sync_work(struct work_struct *work)
118 {
119 int nowait = 0;
120
121 /*
122 * Sync twice to reduce the possibility we skipped some inodes / pages
123 * because they were temporarily locked
124 */
125 iterate_supers(sync_inodes_one_sb, &nowait);
126 iterate_supers(sync_fs_one_sb, &nowait);
127 iterate_bdevs(fdatawrite_one_bdev, NULL);
128 iterate_supers(sync_inodes_one_sb, &nowait);
129 iterate_supers(sync_fs_one_sb, &nowait);
130 iterate_bdevs(fdatawrite_one_bdev, NULL);
131 printk("Emergency Sync complete\n");
132 kfree(work);
133 }
134
emergency_sync(void)135 void emergency_sync(void)
136 {
137 struct work_struct *work;
138
139 work = kmalloc(sizeof(*work), GFP_ATOMIC);
140 if (work) {
141 INIT_WORK(work, do_sync_work);
142 schedule_work(work);
143 }
144 }
145
146 /*
147 * sync a single super
148 */
SYSCALL_DEFINE1(syncfs,int,fd)149 SYSCALL_DEFINE1(syncfs, int, fd)
150 {
151 struct fd f = fdget(fd);
152 struct super_block *sb;
153 int ret;
154
155 if (!f.file)
156 return -EBADF;
157 sb = f.file->f_dentry->d_sb;
158
159 down_read(&sb->s_umount);
160 ret = sync_filesystem(sb);
161 up_read(&sb->s_umount);
162
163 fdput(f);
164 return ret;
165 }
166
167 /**
168 * vfs_fsync_range - helper to sync a range of data & metadata to disk
169 * @file: file to sync
170 * @start: offset in bytes of the beginning of data range to sync
171 * @end: offset in bytes of the end of data range (inclusive)
172 * @datasync: perform only datasync
173 *
174 * Write back data in range @start..@end and metadata for @file to disk. If
175 * @datasync is set only metadata needed to access modified file data is
176 * written.
177 */
vfs_fsync_range(struct file * file,loff_t start,loff_t end,int datasync)178 int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync)
179 {
180 struct inode *inode = file->f_mapping->host;
181
182 if (!file->f_op->fsync)
183 return -EINVAL;
184 if (!datasync && (inode->i_state & I_DIRTY_TIME)) {
185 spin_lock(&inode->i_lock);
186 inode->i_state &= ~I_DIRTY_TIME;
187 spin_unlock(&inode->i_lock);
188 mark_inode_dirty_sync(inode);
189 }
190 return file->f_op->fsync(file, start, end, datasync);
191 }
192 EXPORT_SYMBOL(vfs_fsync_range);
193
194 /**
195 * vfs_fsync - perform a fsync or fdatasync on a file
196 * @file: file to sync
197 * @datasync: only perform a fdatasync operation
198 *
199 * Write back data and metadata for @file to disk. If @datasync is
200 * set only metadata needed to access modified file data is written.
201 */
vfs_fsync(struct file * file,int datasync)202 int vfs_fsync(struct file *file, int datasync)
203 {
204 return vfs_fsync_range(file, 0, LLONG_MAX, datasync);
205 }
206 EXPORT_SYMBOL(vfs_fsync);
207
do_fsync(unsigned int fd,int datasync)208 static int do_fsync(unsigned int fd, int datasync)
209 {
210 struct fd f = fdget(fd);
211 int ret = -EBADF;
212
213 if (f.file) {
214 ret = vfs_fsync(f.file, datasync);
215 fdput(f);
216 inc_syscfs(current);
217 }
218 return ret;
219 }
220
SYSCALL_DEFINE1(fsync,unsigned int,fd)221 SYSCALL_DEFINE1(fsync, unsigned int, fd)
222 {
223 return do_fsync(fd, 0);
224 }
225
SYSCALL_DEFINE1(fdatasync,unsigned int,fd)226 SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
227 {
228 return do_fsync(fd, 1);
229 }
230
231 /*
232 * sys_sync_file_range() permits finely controlled syncing over a segment of
233 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
234 * zero then sys_sync_file_range() will operate from offset out to EOF.
235 *
236 * The flag bits are:
237 *
238 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
239 * before performing the write.
240 *
241 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
242 * range which are not presently under writeback. Note that this may block for
243 * significant periods due to exhaustion of disk request structures.
244 *
245 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
246 * after performing the write.
247 *
248 * Useful combinations of the flag bits are:
249 *
250 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
251 * in the range which were dirty on entry to sys_sync_file_range() are placed
252 * under writeout. This is a start-write-for-data-integrity operation.
253 *
254 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
255 * are not presently under writeout. This is an asynchronous flush-to-disk
256 * operation. Not suitable for data integrity operations.
257 *
258 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
259 * completion of writeout of all pages in the range. This will be used after an
260 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
261 * for that operation to complete and to return the result.
262 *
263 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
264 * a traditional sync() operation. This is a write-for-data-integrity operation
265 * which will ensure that all pages in the range which were dirty on entry to
266 * sys_sync_file_range() are committed to disk.
267 *
268 *
269 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
270 * I/O errors or ENOSPC conditions and will return those to the caller, after
271 * clearing the EIO and ENOSPC flags in the address_space.
272 *
273 * It should be noted that none of these operations write out the file's
274 * metadata. So unless the application is strictly performing overwrites of
275 * already-instantiated disk blocks, there are no guarantees here that the data
276 * will be available after a crash.
277 */
SYSCALL_DEFINE4(sync_file_range,int,fd,loff_t,offset,loff_t,nbytes,unsigned int,flags)278 SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes,
279 unsigned int, flags)
280 {
281 int ret;
282 struct fd f;
283 struct address_space *mapping;
284 loff_t endbyte; /* inclusive */
285 umode_t i_mode;
286
287 ret = -EINVAL;
288 if (flags & ~VALID_FLAGS)
289 goto out;
290
291 endbyte = offset + nbytes;
292
293 if ((s64)offset < 0)
294 goto out;
295 if ((s64)endbyte < 0)
296 goto out;
297 if (endbyte < offset)
298 goto out;
299
300 if (sizeof(pgoff_t) == 4) {
301 if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
302 /*
303 * The range starts outside a 32 bit machine's
304 * pagecache addressing capabilities. Let it "succeed"
305 */
306 ret = 0;
307 goto out;
308 }
309 if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
310 /*
311 * Out to EOF
312 */
313 nbytes = 0;
314 }
315 }
316
317 if (nbytes == 0)
318 endbyte = LLONG_MAX;
319 else
320 endbyte--; /* inclusive */
321
322 ret = -EBADF;
323 f = fdget(fd);
324 if (!f.file)
325 goto out;
326
327 i_mode = file_inode(f.file)->i_mode;
328 ret = -ESPIPE;
329 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
330 !S_ISLNK(i_mode))
331 goto out_put;
332
333 mapping = f.file->f_mapping;
334 if (!mapping) {
335 ret = -EINVAL;
336 goto out_put;
337 }
338
339 ret = 0;
340 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
341 ret = filemap_fdatawait_range(mapping, offset, endbyte);
342 if (ret < 0)
343 goto out_put;
344 }
345
346 if (flags & SYNC_FILE_RANGE_WRITE) {
347 ret = filemap_fdatawrite_range(mapping, offset, endbyte);
348 if (ret < 0)
349 goto out_put;
350 }
351
352 if (flags & SYNC_FILE_RANGE_WAIT_AFTER)
353 ret = filemap_fdatawait_range(mapping, offset, endbyte);
354
355 out_put:
356 fdput(f);
357 out:
358 return ret;
359 }
360
361 /* It would be nice if people remember that not all the world's an i386
362 when they introduce new system calls */
SYSCALL_DEFINE4(sync_file_range2,int,fd,unsigned int,flags,loff_t,offset,loff_t,nbytes)363 SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags,
364 loff_t, offset, loff_t, nbytes)
365 {
366 return sys_sync_file_range(fd, offset, nbytes, flags);
367 }
368