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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/slab.h> |
9 | #include <linux/module.h> |
10 | #include <linux/sched.h> |
11 | #include <linux/writeback.h> |
12 | #include <linux/syscalls.h> |
13 | #include <linux/linkage.h> |
14 | #include <linux/pagemap.h> |
15 | #include <linux/quotaops.h> |
16 | #include <linux/buffer_head.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 | */ |
30 | static int __sync_filesystem(struct super_block *sb, int wait) |
31 | { |
32 | /* |
33 | * This should be safe, as we require bdi backing to actually |
34 | * write out data in the first place |
35 | */ |
36 | if (!sb->s_bdi || sb->s_bdi == &noop_backing_dev_info) |
37 | return 0; |
38 | |
39 | if (sb->s_qcop && sb->s_qcop->quota_sync) |
40 | sb->s_qcop->quota_sync(sb, -1, wait); |
41 | |
42 | if (wait) |
43 | sync_inodes_sb(sb); |
44 | else |
45 | writeback_inodes_sb(sb); |
46 | |
47 | if (sb->s_op->sync_fs) |
48 | sb->s_op->sync_fs(sb, wait); |
49 | return __sync_blockdev(sb->s_bdev, wait); |
50 | } |
51 | |
52 | /* |
53 | * Write out and wait upon all dirty data associated with this |
54 | * superblock. Filesystem data as well as the underlying block |
55 | * device. Takes the superblock lock. |
56 | */ |
57 | int sync_filesystem(struct super_block *sb) |
58 | { |
59 | int ret; |
60 | |
61 | /* |
62 | * We need to be protected against the filesystem going from |
63 | * r/o to r/w or vice versa. |
64 | */ |
65 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
66 | |
67 | /* |
68 | * No point in syncing out anything if the filesystem is read-only. |
69 | */ |
70 | if (sb->s_flags & MS_RDONLY) |
71 | return 0; |
72 | |
73 | ret = __sync_filesystem(sb, 0); |
74 | if (ret < 0) |
75 | return ret; |
76 | return __sync_filesystem(sb, 1); |
77 | } |
78 | EXPORT_SYMBOL_GPL(sync_filesystem); |
79 | |
80 | /* |
81 | * Sync all the data for all the filesystems (called by sys_sync() and |
82 | * emergency sync) |
83 | * |
84 | * This operation is careful to avoid the livelock which could easily happen |
85 | * if two or more filesystems are being continuously dirtied. s_need_sync |
86 | * is used only here. We set it against all filesystems and then clear it as |
87 | * we sync them. So redirtied filesystems are skipped. |
88 | * |
89 | * But if process A is currently running sync_filesystems and then process B |
90 | * calls sync_filesystems as well, process B will set all the s_need_sync |
91 | * flags again, which will cause process A to resync everything. Fix that with |
92 | * a local mutex. |
93 | */ |
94 | static void sync_filesystems(int wait) |
95 | { |
96 | struct super_block *sb; |
97 | static DEFINE_MUTEX(mutex); |
98 | |
99 | mutex_lock(&mutex); /* Could be down_interruptible */ |
100 | spin_lock(&sb_lock); |
101 | list_for_each_entry(sb, &super_blocks, s_list) |
102 | sb->s_need_sync = 1; |
103 | |
104 | restart: |
105 | list_for_each_entry(sb, &super_blocks, s_list) { |
106 | if (!sb->s_need_sync) |
107 | continue; |
108 | sb->s_need_sync = 0; |
109 | sb->s_count++; |
110 | spin_unlock(&sb_lock); |
111 | |
112 | down_read(&sb->s_umount); |
113 | if (!(sb->s_flags & MS_RDONLY) && sb->s_root && sb->s_bdi) |
114 | __sync_filesystem(sb, wait); |
115 | up_read(&sb->s_umount); |
116 | |
117 | /* restart only when sb is no longer on the list */ |
118 | spin_lock(&sb_lock); |
119 | if (__put_super_and_need_restart(sb)) |
120 | goto restart; |
121 | } |
122 | spin_unlock(&sb_lock); |
123 | mutex_unlock(&mutex); |
124 | } |
125 | |
126 | /* |
127 | * sync everything. Start out by waking pdflush, because that writes back |
128 | * all queues in parallel. |
129 | */ |
130 | SYSCALL_DEFINE0(sync) |
131 | { |
132 | wakeup_flusher_threads(0); |
133 | sync_filesystems(0); |
134 | sync_filesystems(1); |
135 | if (unlikely(laptop_mode)) |
136 | laptop_sync_completion(); |
137 | return 0; |
138 | } |
139 | |
140 | static void do_sync_work(struct work_struct *work) |
141 | { |
142 | /* |
143 | * Sync twice to reduce the possibility we skipped some inodes / pages |
144 | * because they were temporarily locked |
145 | */ |
146 | sync_filesystems(0); |
147 | sync_filesystems(0); |
148 | printk("Emergency Sync complete\n"); |
149 | kfree(work); |
150 | } |
151 | |
152 | void emergency_sync(void) |
153 | { |
154 | struct work_struct *work; |
155 | |
156 | work = kmalloc(sizeof(*work), GFP_ATOMIC); |
157 | if (work) { |
158 | INIT_WORK(work, do_sync_work); |
159 | schedule_work(work); |
160 | } |
161 | } |
162 | |
163 | /* |
164 | * Generic function to fsync a file. |
165 | * |
166 | * filp may be NULL if called via the msync of a vma. |
167 | */ |
168 | int file_fsync(struct file *filp, struct dentry *dentry, int datasync) |
169 | { |
170 | struct inode * inode = dentry->d_inode; |
171 | struct super_block * sb; |
172 | int ret, err; |
173 | |
174 | /* sync the inode to buffers */ |
175 | ret = write_inode_now(inode, 0); |
176 | |
177 | /* sync the superblock to buffers */ |
178 | sb = inode->i_sb; |
179 | if (sb->s_dirt && sb->s_op->write_super) |
180 | sb->s_op->write_super(sb); |
181 | |
182 | /* .. finally sync the buffers to disk */ |
183 | err = sync_blockdev(sb->s_bdev); |
184 | if (!ret) |
185 | ret = err; |
186 | return ret; |
187 | } |
188 | EXPORT_SYMBOL(file_fsync); |
189 | |
190 | /** |
191 | * vfs_fsync_range - helper to sync a range of data & metadata to disk |
192 | * @file: file to sync |
193 | * @dentry: dentry of @file |
194 | * @start: offset in bytes of the beginning of data range to sync |
195 | * @end: offset in bytes of the end of data range (inclusive) |
196 | * @datasync: perform only datasync |
197 | * |
198 | * Write back data in range @start..@end and metadata for @file to disk. If |
199 | * @datasync is set only metadata needed to access modified file data is |
200 | * written. |
201 | * |
202 | * In case this function is called from nfsd @file may be %NULL and |
203 | * only @dentry is set. This can only happen when the filesystem |
204 | * implements the export_operations API. |
205 | */ |
206 | int vfs_fsync_range(struct file *file, struct dentry *dentry, loff_t start, |
207 | loff_t end, int datasync) |
208 | { |
209 | const struct file_operations *fop; |
210 | struct address_space *mapping; |
211 | int err, ret; |
212 | |
213 | /* |
214 | * Get mapping and operations from the file in case we have |
215 | * as file, or get the default values for them in case we |
216 | * don't have a struct file available. Damn nfsd.. |
217 | */ |
218 | if (file) { |
219 | mapping = file->f_mapping; |
220 | fop = file->f_op; |
221 | } else { |
222 | mapping = dentry->d_inode->i_mapping; |
223 | fop = dentry->d_inode->i_fop; |
224 | } |
225 | |
226 | if (!fop || !fop->fsync) { |
227 | ret = -EINVAL; |
228 | goto out; |
229 | } |
230 | |
231 | ret = filemap_write_and_wait_range(mapping, start, end); |
232 | |
233 | /* |
234 | * We need to protect against concurrent writers, which could cause |
235 | * livelocks in fsync_buffers_list(). |
236 | */ |
237 | mutex_lock(&mapping->host->i_mutex); |
238 | err = fop->fsync(file, dentry, datasync); |
239 | if (!ret) |
240 | ret = err; |
241 | mutex_unlock(&mapping->host->i_mutex); |
242 | |
243 | out: |
244 | return ret; |
245 | } |
246 | EXPORT_SYMBOL(vfs_fsync_range); |
247 | |
248 | /** |
249 | * vfs_fsync - perform a fsync or fdatasync on a file |
250 | * @file: file to sync |
251 | * @dentry: dentry of @file |
252 | * @datasync: only perform a fdatasync operation |
253 | * |
254 | * Write back data and metadata for @file to disk. If @datasync is |
255 | * set only metadata needed to access modified file data is written. |
256 | * |
257 | * In case this function is called from nfsd @file may be %NULL and |
258 | * only @dentry is set. This can only happen when the filesystem |
259 | * implements the export_operations API. |
260 | */ |
261 | int vfs_fsync(struct file *file, struct dentry *dentry, int datasync) |
262 | { |
263 | return vfs_fsync_range(file, dentry, 0, LLONG_MAX, datasync); |
264 | } |
265 | EXPORT_SYMBOL(vfs_fsync); |
266 | |
267 | static int do_fsync(unsigned int fd, int datasync) |
268 | { |
269 | struct file *file; |
270 | int ret = -EBADF; |
271 | |
272 | file = fget(fd); |
273 | if (file) { |
274 | ret = vfs_fsync(file, file->f_path.dentry, datasync); |
275 | fput(file); |
276 | } |
277 | return ret; |
278 | } |
279 | |
280 | SYSCALL_DEFINE1(fsync, unsigned int, fd) |
281 | { |
282 | return do_fsync(fd, 0); |
283 | } |
284 | |
285 | SYSCALL_DEFINE1(fdatasync, unsigned int, fd) |
286 | { |
287 | return do_fsync(fd, 1); |
288 | } |
289 | |
290 | /** |
291 | * generic_write_sync - perform syncing after a write if file / inode is sync |
292 | * @file: file to which the write happened |
293 | * @pos: offset where the write started |
294 | * @count: length of the write |
295 | * |
296 | * This is just a simple wrapper about our general syncing function. |
297 | */ |
298 | int generic_write_sync(struct file *file, loff_t pos, loff_t count) |
299 | { |
300 | if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host)) |
301 | return 0; |
302 | return vfs_fsync_range(file, file->f_path.dentry, pos, |
303 | pos + count - 1, |
304 | (file->f_flags & __O_SYNC) ? 0 : 1); |
305 | } |
306 | EXPORT_SYMBOL(generic_write_sync); |
307 | |
308 | /* |
309 | * sys_sync_file_range() permits finely controlled syncing over a segment of |
310 | * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is |
311 | * zero then sys_sync_file_range() will operate from offset out to EOF. |
312 | * |
313 | * The flag bits are: |
314 | * |
315 | * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range |
316 | * before performing the write. |
317 | * |
318 | * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the |
319 | * range which are not presently under writeback. Note that this may block for |
320 | * significant periods due to exhaustion of disk request structures. |
321 | * |
322 | * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range |
323 | * after performing the write. |
324 | * |
325 | * Useful combinations of the flag bits are: |
326 | * |
327 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages |
328 | * in the range which were dirty on entry to sys_sync_file_range() are placed |
329 | * under writeout. This is a start-write-for-data-integrity operation. |
330 | * |
331 | * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which |
332 | * are not presently under writeout. This is an asynchronous flush-to-disk |
333 | * operation. Not suitable for data integrity operations. |
334 | * |
335 | * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for |
336 | * completion of writeout of all pages in the range. This will be used after an |
337 | * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait |
338 | * for that operation to complete and to return the result. |
339 | * |
340 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: |
341 | * a traditional sync() operation. This is a write-for-data-integrity operation |
342 | * which will ensure that all pages in the range which were dirty on entry to |
343 | * sys_sync_file_range() are committed to disk. |
344 | * |
345 | * |
346 | * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any |
347 | * I/O errors or ENOSPC conditions and will return those to the caller, after |
348 | * clearing the EIO and ENOSPC flags in the address_space. |
349 | * |
350 | * It should be noted that none of these operations write out the file's |
351 | * metadata. So unless the application is strictly performing overwrites of |
352 | * already-instantiated disk blocks, there are no guarantees here that the data |
353 | * will be available after a crash. |
354 | */ |
355 | SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes, |
356 | unsigned int flags) |
357 | { |
358 | int ret; |
359 | struct file *file; |
360 | struct address_space *mapping; |
361 | loff_t endbyte; /* inclusive */ |
362 | int fput_needed; |
363 | umode_t i_mode; |
364 | |
365 | ret = -EINVAL; |
366 | if (flags & ~VALID_FLAGS) |
367 | goto out; |
368 | |
369 | endbyte = offset + nbytes; |
370 | |
371 | if ((s64)offset < 0) |
372 | goto out; |
373 | if ((s64)endbyte < 0) |
374 | goto out; |
375 | if (endbyte < offset) |
376 | goto out; |
377 | |
378 | if (sizeof(pgoff_t) == 4) { |
379 | if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { |
380 | /* |
381 | * The range starts outside a 32 bit machine's |
382 | * pagecache addressing capabilities. Let it "succeed" |
383 | */ |
384 | ret = 0; |
385 | goto out; |
386 | } |
387 | if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { |
388 | /* |
389 | * Out to EOF |
390 | */ |
391 | nbytes = 0; |
392 | } |
393 | } |
394 | |
395 | if (nbytes == 0) |
396 | endbyte = LLONG_MAX; |
397 | else |
398 | endbyte--; /* inclusive */ |
399 | |
400 | ret = -EBADF; |
401 | file = fget_light(fd, &fput_needed); |
402 | if (!file) |
403 | goto out; |
404 | |
405 | i_mode = file->f_path.dentry->d_inode->i_mode; |
406 | ret = -ESPIPE; |
407 | if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && |
408 | !S_ISLNK(i_mode)) |
409 | goto out_put; |
410 | |
411 | mapping = file->f_mapping; |
412 | if (!mapping) { |
413 | ret = -EINVAL; |
414 | goto out_put; |
415 | } |
416 | |
417 | ret = 0; |
418 | if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { |
419 | ret = filemap_fdatawait_range(mapping, offset, endbyte); |
420 | if (ret < 0) |
421 | goto out_put; |
422 | } |
423 | |
424 | if (flags & SYNC_FILE_RANGE_WRITE) { |
425 | ret = filemap_fdatawrite_range(mapping, offset, endbyte); |
426 | if (ret < 0) |
427 | goto out_put; |
428 | } |
429 | |
430 | if (flags & SYNC_FILE_RANGE_WAIT_AFTER) |
431 | ret = filemap_fdatawait_range(mapping, offset, endbyte); |
432 | |
433 | out_put: |
434 | fput_light(file, fput_needed); |
435 | out: |
436 | return ret; |
437 | } |
438 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
439 | asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes, |
440 | long flags) |
441 | { |
442 | return SYSC_sync_file_range((int) fd, offset, nbytes, |
443 | (unsigned int) flags); |
444 | } |
445 | SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range); |
446 | #endif |
447 | |
448 | /* It would be nice if people remember that not all the world's an i386 |
449 | when they introduce new system calls */ |
450 | SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags, |
451 | loff_t offset, loff_t nbytes) |
452 | { |
453 | return sys_sync_file_range(fd, offset, nbytes, flags); |
454 | } |
455 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
456 | asmlinkage long SyS_sync_file_range2(long fd, long flags, |
457 | loff_t offset, loff_t nbytes) |
458 | { |
459 | return SYSC_sync_file_range2((int) fd, (unsigned int) flags, |
460 | offset, nbytes); |
461 | } |
462 | SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2); |
463 | #endif |
464 |
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