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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 #include "internal.h"
17
18 #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
19 SYNC_FILE_RANGE_WAIT_AFTER)
20
21 /*
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.
27 */
28 static int __sync_filesystem(struct super_block *sb, int wait)
29 {
30 /* Avoid doing twice syncing and cache pruning for quota sync */
31 if (!wait)
32 writeout_quota_sb(sb, -1);
33 else
34 sync_quota_sb(sb, -1);
35 sync_inodes_sb(sb, wait);
36 lock_super(sb);
37 if (sb->s_dirt && sb->s_op->write_super)
38 sb->s_op->write_super(sb);
39 unlock_super(sb);
40 if (sb->s_op->sync_fs)
41 sb->s_op->sync_fs(sb, wait);
42 return __sync_blockdev(sb->s_bdev, wait);
43 }
44
45 /*
46 * Write out and wait upon all dirty data associated with this
47 * superblock. Filesystem data as well as the underlying block
48 * device. Takes the superblock lock.
49 */
50 int sync_filesystem(struct super_block *sb)
51 {
52 int ret;
53
54 /*
55 * We need to be protected against the filesystem going from
56 * r/o to r/w or vice versa.
57 */
58 WARN_ON(!rwsem_is_locked(&sb->s_umount));
59
60 /*
61 * No point in syncing out anything if the filesystem is read-only.
62 */
63 if (sb->s_flags & MS_RDONLY)
64 return 0;
65
66 ret = __sync_filesystem(sb, 0);
67 if (ret < 0)
68 return ret;
69 return __sync_filesystem(sb, 1);
70 }
71 EXPORT_SYMBOL_GPL(sync_filesystem);
72
73 /*
74 * Sync all the data for all the filesystems (called by sys_sync() and
75 * emergency sync)
76 *
77 * This operation is careful to avoid the livelock which could easily happen
78 * if two or more filesystems are being continuously dirtied. s_need_sync
79 * is used only here. We set it against all filesystems and then clear it as
80 * we sync them. So redirtied filesystems are skipped.
81 *
82 * But if process A is currently running sync_filesystems and then process B
83 * calls sync_filesystems as well, process B will set all the s_need_sync
84 * flags again, which will cause process A to resync everything. Fix that with
85 * a local mutex.
86 */
87 static void sync_filesystems(int wait)
88 {
89 struct super_block *sb;
90 static DEFINE_MUTEX(mutex);
91
92 mutex_lock(&mutex); /* Could be down_interruptible */
93 spin_lock(&sb_lock);
94 list_for_each_entry(sb, &super_blocks, s_list)
95 sb->s_need_sync = 1;
96
97 restart:
98 list_for_each_entry(sb, &super_blocks, s_list) {
99 if (!sb->s_need_sync)
100 continue;
101 sb->s_need_sync = 0;
102 sb->s_count++;
103 spin_unlock(&sb_lock);
104
105 down_read(&sb->s_umount);
106 if (!(sb->s_flags & MS_RDONLY) && sb->s_root)
107 __sync_filesystem(sb, wait);
108 up_read(&sb->s_umount);
109
110 /* restart only when sb is no longer on the list */
111 spin_lock(&sb_lock);
112 if (__put_super_and_need_restart(sb))
113 goto restart;
114 }
115 spin_unlock(&sb_lock);
116 mutex_unlock(&mutex);
117 }
118
119 SYSCALL_DEFINE0(sync)
120 {
121 sync_filesystems(0);
122 sync_filesystems(1);
123 if (unlikely(laptop_mode))
124 laptop_sync_completion();
125 return 0;
126 }
127
128 static void do_sync_work(struct work_struct *work)
129 {
130 /*
131 * Sync twice to reduce the possibility we skipped some inodes / pages
132 * because they were temporarily locked
133 */
134 sync_filesystems(0);
135 sync_filesystems(0);
136 printk("Emergency Sync complete\n");
137 kfree(work);
138 }
139
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 * Generic function to fsync a file.
153 *
154 * filp may be NULL if called via the msync of a vma.
155 */
156 int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
157 {
158 struct inode * inode = dentry->d_inode;
159 struct super_block * sb;
160 int ret, err;
161
162 /* sync the inode to buffers */
163 ret = write_inode_now(inode, 0);
164
165 /* sync the superblock to buffers */
166 sb = inode->i_sb;
167 lock_super(sb);
168 if (sb->s_dirt && sb->s_op->write_super)
169 sb->s_op->write_super(sb);
170 unlock_super(sb);
171
172 /* .. finally sync the buffers to disk */
173 err = sync_blockdev(sb->s_bdev);
174 if (!ret)
175 ret = err;
176 return ret;
177 }
178
179 /**
180 * vfs_fsync - perform a fsync or fdatasync on a file
181 * @file: file to sync
182 * @dentry: dentry of @file
183 * @data: only perform a fdatasync operation
184 *
185 * Write back data and metadata for @file to disk. If @datasync is
186 * set only metadata needed to access modified file data is written.
187 *
188 * In case this function is called from nfsd @file may be %NULL and
189 * only @dentry is set. This can only happen when the filesystem
190 * implements the export_operations API.
191 */
192 int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)
193 {
194 const struct file_operations *fop;
195 struct address_space *mapping;
196 int err, ret;
197
198 /*
199 * Get mapping and operations from the file in case we have
200 * as file, or get the default values for them in case we
201 * don't have a struct file available. Damn nfsd..
202 */
203 if (file) {
204 mapping = file->f_mapping;
205 fop = file->f_op;
206 } else {
207 mapping = dentry->d_inode->i_mapping;
208 fop = dentry->d_inode->i_fop;
209 }
210
211 if (!fop || !fop->fsync) {
212 ret = -EINVAL;
213 goto out;
214 }
215
216 ret = filemap_fdatawrite(mapping);
217
218 /*
219 * We need to protect against concurrent writers, which could cause
220 * livelocks in fsync_buffers_list().
221 */
222 mutex_lock(&mapping->host->i_mutex);
223 err = fop->fsync(file, dentry, datasync);
224 if (!ret)
225 ret = err;
226 mutex_unlock(&mapping->host->i_mutex);
227 err = filemap_fdatawait(mapping);
228 if (!ret)
229 ret = err;
230 out:
231 return ret;
232 }
233 EXPORT_SYMBOL(vfs_fsync);
234
235 static int do_fsync(unsigned int fd, int datasync)
236 {
237 struct file *file;
238 int ret = -EBADF;
239
240 file = fget(fd);
241 if (file) {
242 ret = vfs_fsync(file, file->f_path.dentry, datasync);
243 fput(file);
244 }
245 return ret;
246 }
247
248 SYSCALL_DEFINE1(fsync, unsigned int, fd)
249 {
250 return do_fsync(fd, 0);
251 }
252
253 SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
254 {
255 return do_fsync(fd, 1);
256 }
257
258 /*
259 * sys_sync_file_range() permits finely controlled syncing over a segment of
260 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
261 * zero then sys_sync_file_range() will operate from offset out to EOF.
262 *
263 * The flag bits are:
264 *
265 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
266 * before performing the write.
267 *
268 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
269 * range which are not presently under writeback. Note that this may block for
270 * significant periods due to exhaustion of disk request structures.
271 *
272 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
273 * after performing the write.
274 *
275 * Useful combinations of the flag bits are:
276 *
277 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
278 * in the range which were dirty on entry to sys_sync_file_range() are placed
279 * under writeout. This is a start-write-for-data-integrity operation.
280 *
281 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
282 * are not presently under writeout. This is an asynchronous flush-to-disk
283 * operation. Not suitable for data integrity operations.
284 *
285 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
286 * completion of writeout of all pages in the range. This will be used after an
287 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
288 * for that operation to complete and to return the result.
289 *
290 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
291 * a traditional sync() operation. This is a write-for-data-integrity operation
292 * which will ensure that all pages in the range which were dirty on entry to
293 * sys_sync_file_range() are committed to disk.
294 *
295 *
296 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
297 * I/O errors or ENOSPC conditions and will return those to the caller, after
298 * clearing the EIO and ENOSPC flags in the address_space.
299 *
300 * It should be noted that none of these operations write out the file's
301 * metadata. So unless the application is strictly performing overwrites of
302 * already-instantiated disk blocks, there are no guarantees here that the data
303 * will be available after a crash.
304 */
305 SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes,
306 unsigned int flags)
307 {
308 int ret;
309 struct file *file;
310 loff_t endbyte; /* inclusive */
311 int fput_needed;
312 umode_t i_mode;
313
314 ret = -EINVAL;
315 if (flags & ~VALID_FLAGS)
316 goto out;
317
318 endbyte = offset + nbytes;
319
320 if ((s64)offset < 0)
321 goto out;
322 if ((s64)endbyte < 0)
323 goto out;
324 if (endbyte < offset)
325 goto out;
326
327 if (sizeof(pgoff_t) == 4) {
328 if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
329 /*
330 * The range starts outside a 32 bit machine's
331 * pagecache addressing capabilities. Let it "succeed"
332 */
333 ret = 0;
334 goto out;
335 }
336 if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
337 /*
338 * Out to EOF
339 */
340 nbytes = 0;
341 }
342 }
343
344 if (nbytes == 0)
345 endbyte = LLONG_MAX;
346 else
347 endbyte--; /* inclusive */
348
349 ret = -EBADF;
350 file = fget_light(fd, &fput_needed);
351 if (!file)
352 goto out;
353
354 i_mode = file->f_path.dentry->d_inode->i_mode;
355 ret = -ESPIPE;
356 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
357 !S_ISLNK(i_mode))
358 goto out_put;
359
360 ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags);
361 out_put:
362 fput_light(file, fput_needed);
363 out:
364 return ret;
365 }
366 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
367 asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes,
368 long flags)
369 {
370 return SYSC_sync_file_range((int) fd, offset, nbytes,
371 (unsigned int) flags);
372 }
373 SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range);
374 #endif
375
376 /* It would be nice if people remember that not all the world's an i386
377 when they introduce new system calls */
378 SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags,
379 loff_t offset, loff_t nbytes)
380 {
381 return sys_sync_file_range(fd, offset, nbytes, flags);
382 }
383 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
384 asmlinkage long SyS_sync_file_range2(long fd, long flags,
385 loff_t offset, loff_t nbytes)
386 {
387 return SYSC_sync_file_range2((int) fd, (unsigned int) flags,
388 offset, nbytes);
389 }
390 SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2);
391 #endif
392
393 /*
394 * `endbyte' is inclusive
395 */
396 int do_sync_mapping_range(struct address_space *mapping, loff_t offset,
397 loff_t endbyte, unsigned int flags)
398 {
399 int ret;
400
401 if (!mapping) {
402 ret = -EINVAL;
403 goto out;
404 }
405
406 ret = 0;
407 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
408 ret = wait_on_page_writeback_range(mapping,
409 offset >> PAGE_CACHE_SHIFT,
410 endbyte >> PAGE_CACHE_SHIFT);
411 if (ret < 0)
412 goto out;
413 }
414
415 if (flags & SYNC_FILE_RANGE_WRITE) {
416 ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
417 WB_SYNC_ALL);
418 if (ret < 0)
419 goto out;
420 }
421
422 if (flags & SYNC_FILE_RANGE_WAIT_AFTER) {
423 ret = wait_on_page_writeback_range(mapping,
424 offset >> PAGE_CACHE_SHIFT,
425 endbyte >> PAGE_CACHE_SHIFT);
426 }
427 out:
428 return ret;
429 }
430 EXPORT_SYMBOL_GPL(do_sync_mapping_range);