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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/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/buffer_head.h> |
18 | #include <linux/backing-dev.h> |
19 | #include "internal.h" |
20 | |
21 | #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \ |
22 | SYNC_FILE_RANGE_WAIT_AFTER) |
23 | |
24 | /* |
25 | * Do the filesystem syncing work. For simple filesystems |
26 | * writeback_inodes_sb(sb) just dirties buffers with inodes so we have to |
27 | * submit IO for these buffers via __sync_blockdev(). This also speeds up the |
28 | * wait == 1 case since in that case write_inode() functions do |
29 | * sync_dirty_buffer() and thus effectively write one block at a time. |
30 | */ |
31 | static int __sync_filesystem(struct super_block *sb, int wait) |
32 | { |
33 | /* |
34 | * This should be safe, as we require bdi backing to actually |
35 | * write out data in the first place |
36 | */ |
37 | if (sb->s_bdi == &noop_backing_dev_info) |
38 | return 0; |
39 | |
40 | if (sb->s_qcop && sb->s_qcop->quota_sync) |
41 | sb->s_qcop->quota_sync(sb, -1, wait); |
42 | |
43 | if (wait) |
44 | sync_inodes_sb(sb); |
45 | else |
46 | writeback_inodes_sb(sb); |
47 | |
48 | if (sb->s_op->sync_fs) |
49 | sb->s_op->sync_fs(sb, wait); |
50 | return __sync_blockdev(sb->s_bdev, wait); |
51 | } |
52 | |
53 | /* |
54 | * Write out and wait upon all dirty data associated with this |
55 | * superblock. Filesystem data as well as the underlying block |
56 | * device. Takes the superblock lock. |
57 | */ |
58 | int sync_filesystem(struct super_block *sb) |
59 | { |
60 | int ret; |
61 | |
62 | /* |
63 | * We need to be protected against the filesystem going from |
64 | * r/o to r/w or vice versa. |
65 | */ |
66 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
67 | |
68 | /* |
69 | * No point in syncing out anything if the filesystem is read-only. |
70 | */ |
71 | if (sb->s_flags & MS_RDONLY) |
72 | return 0; |
73 | |
74 | ret = __sync_filesystem(sb, 0); |
75 | if (ret < 0) |
76 | return ret; |
77 | return __sync_filesystem(sb, 1); |
78 | } |
79 | EXPORT_SYMBOL_GPL(sync_filesystem); |
80 | |
81 | static void sync_one_sb(struct super_block *sb, void *arg) |
82 | { |
83 | if (!(sb->s_flags & MS_RDONLY)) |
84 | __sync_filesystem(sb, *(int *)arg); |
85 | } |
86 | /* |
87 | * Sync all the data for all the filesystems (called by sys_sync() and |
88 | * emergency sync) |
89 | */ |
90 | static void sync_filesystems(int wait) |
91 | { |
92 | iterate_supers(sync_one_sb, &wait); |
93 | } |
94 | |
95 | /* |
96 | * sync everything. Start out by waking pdflush, because that writes back |
97 | * all queues in parallel. |
98 | */ |
99 | SYSCALL_DEFINE0(sync) |
100 | { |
101 | wakeup_flusher_threads(0); |
102 | sync_filesystems(0); |
103 | sync_filesystems(1); |
104 | if (unlikely(laptop_mode)) |
105 | laptop_sync_completion(); |
106 | return 0; |
107 | } |
108 | |
109 | static void do_sync_work(struct work_struct *work) |
110 | { |
111 | /* |
112 | * Sync twice to reduce the possibility we skipped some inodes / pages |
113 | * because they were temporarily locked |
114 | */ |
115 | sync_filesystems(0); |
116 | sync_filesystems(0); |
117 | printk("Emergency Sync complete\n"); |
118 | kfree(work); |
119 | } |
120 | |
121 | void emergency_sync(void) |
122 | { |
123 | struct work_struct *work; |
124 | |
125 | work = kmalloc(sizeof(*work), GFP_ATOMIC); |
126 | if (work) { |
127 | INIT_WORK(work, do_sync_work); |
128 | schedule_work(work); |
129 | } |
130 | } |
131 | |
132 | /* |
133 | * sync a single super |
134 | */ |
135 | SYSCALL_DEFINE1(syncfs, int, fd) |
136 | { |
137 | struct file *file; |
138 | struct super_block *sb; |
139 | int ret; |
140 | int fput_needed; |
141 | |
142 | file = fget_light(fd, &fput_needed); |
143 | if (!file) |
144 | return -EBADF; |
145 | sb = file->f_dentry->d_sb; |
146 | |
147 | down_read(&sb->s_umount); |
148 | ret = sync_filesystem(sb); |
149 | up_read(&sb->s_umount); |
150 | |
151 | fput_light(file, fput_needed); |
152 | return ret; |
153 | } |
154 | |
155 | /** |
156 | * vfs_fsync_range - helper to sync a range of data & metadata to disk |
157 | * @file: file to sync |
158 | * @start: offset in bytes of the beginning of data range to sync |
159 | * @end: offset in bytes of the end of data range (inclusive) |
160 | * @datasync: perform only datasync |
161 | * |
162 | * Write back data in range @start..@end and metadata for @file to disk. If |
163 | * @datasync is set only metadata needed to access modified file data is |
164 | * written. |
165 | */ |
166 | int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) |
167 | { |
168 | struct address_space *mapping = file->f_mapping; |
169 | int err, ret; |
170 | |
171 | if (!file->f_op || !file->f_op->fsync) { |
172 | ret = -EINVAL; |
173 | goto out; |
174 | } |
175 | |
176 | ret = filemap_write_and_wait_range(mapping, start, end); |
177 | |
178 | /* |
179 | * We need to protect against concurrent writers, which could cause |
180 | * livelocks in fsync_buffers_list(). |
181 | */ |
182 | mutex_lock(&mapping->host->i_mutex); |
183 | err = file->f_op->fsync(file, datasync); |
184 | if (!ret) |
185 | ret = err; |
186 | mutex_unlock(&mapping->host->i_mutex); |
187 | |
188 | out: |
189 | return ret; |
190 | } |
191 | EXPORT_SYMBOL(vfs_fsync_range); |
192 | |
193 | /** |
194 | * vfs_fsync - perform a fsync or fdatasync on a file |
195 | * @file: file to sync |
196 | * @datasync: only perform a fdatasync operation |
197 | * |
198 | * Write back data and metadata for @file to disk. If @datasync is |
199 | * set only metadata needed to access modified file data is written. |
200 | */ |
201 | int vfs_fsync(struct file *file, int datasync) |
202 | { |
203 | return vfs_fsync_range(file, 0, LLONG_MAX, datasync); |
204 | } |
205 | EXPORT_SYMBOL(vfs_fsync); |
206 | |
207 | static int do_fsync(unsigned int fd, int datasync) |
208 | { |
209 | struct file *file; |
210 | int ret = -EBADF; |
211 | |
212 | file = fget(fd); |
213 | if (file) { |
214 | ret = vfs_fsync(file, datasync); |
215 | fput(file); |
216 | } |
217 | return ret; |
218 | } |
219 | |
220 | SYSCALL_DEFINE1(fsync, unsigned int, fd) |
221 | { |
222 | return do_fsync(fd, 0); |
223 | } |
224 | |
225 | SYSCALL_DEFINE1(fdatasync, unsigned int, fd) |
226 | { |
227 | return do_fsync(fd, 1); |
228 | } |
229 | |
230 | /** |
231 | * generic_write_sync - perform syncing after a write if file / inode is sync |
232 | * @file: file to which the write happened |
233 | * @pos: offset where the write started |
234 | * @count: length of the write |
235 | * |
236 | * This is just a simple wrapper about our general syncing function. |
237 | */ |
238 | int generic_write_sync(struct file *file, loff_t pos, loff_t count) |
239 | { |
240 | if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host)) |
241 | return 0; |
242 | return vfs_fsync_range(file, pos, pos + count - 1, |
243 | (file->f_flags & __O_SYNC) ? 0 : 1); |
244 | } |
245 | EXPORT_SYMBOL(generic_write_sync); |
246 | |
247 | /* |
248 | * sys_sync_file_range() permits finely controlled syncing over a segment of |
249 | * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is |
250 | * zero then sys_sync_file_range() will operate from offset out to EOF. |
251 | * |
252 | * The flag bits are: |
253 | * |
254 | * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range |
255 | * before performing the write. |
256 | * |
257 | * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the |
258 | * range which are not presently under writeback. Note that this may block for |
259 | * significant periods due to exhaustion of disk request structures. |
260 | * |
261 | * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range |
262 | * after performing the write. |
263 | * |
264 | * Useful combinations of the flag bits are: |
265 | * |
266 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages |
267 | * in the range which were dirty on entry to sys_sync_file_range() are placed |
268 | * under writeout. This is a start-write-for-data-integrity operation. |
269 | * |
270 | * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which |
271 | * are not presently under writeout. This is an asynchronous flush-to-disk |
272 | * operation. Not suitable for data integrity operations. |
273 | * |
274 | * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for |
275 | * completion of writeout of all pages in the range. This will be used after an |
276 | * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait |
277 | * for that operation to complete and to return the result. |
278 | * |
279 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: |
280 | * a traditional sync() operation. This is a write-for-data-integrity operation |
281 | * which will ensure that all pages in the range which were dirty on entry to |
282 | * sys_sync_file_range() are committed to disk. |
283 | * |
284 | * |
285 | * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any |
286 | * I/O errors or ENOSPC conditions and will return those to the caller, after |
287 | * clearing the EIO and ENOSPC flags in the address_space. |
288 | * |
289 | * It should be noted that none of these operations write out the file's |
290 | * metadata. So unless the application is strictly performing overwrites of |
291 | * already-instantiated disk blocks, there are no guarantees here that the data |
292 | * will be available after a crash. |
293 | */ |
294 | SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes, |
295 | unsigned int flags) |
296 | { |
297 | int ret; |
298 | struct file *file; |
299 | struct address_space *mapping; |
300 | loff_t endbyte; /* inclusive */ |
301 | int fput_needed; |
302 | umode_t i_mode; |
303 | |
304 | ret = -EINVAL; |
305 | if (flags & ~VALID_FLAGS) |
306 | goto out; |
307 | |
308 | endbyte = offset + nbytes; |
309 | |
310 | if ((s64)offset < 0) |
311 | goto out; |
312 | if ((s64)endbyte < 0) |
313 | goto out; |
314 | if (endbyte < offset) |
315 | goto out; |
316 | |
317 | if (sizeof(pgoff_t) == 4) { |
318 | if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { |
319 | /* |
320 | * The range starts outside a 32 bit machine's |
321 | * pagecache addressing capabilities. Let it "succeed" |
322 | */ |
323 | ret = 0; |
324 | goto out; |
325 | } |
326 | if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { |
327 | /* |
328 | * Out to EOF |
329 | */ |
330 | nbytes = 0; |
331 | } |
332 | } |
333 | |
334 | if (nbytes == 0) |
335 | endbyte = LLONG_MAX; |
336 | else |
337 | endbyte--; /* inclusive */ |
338 | |
339 | ret = -EBADF; |
340 | file = fget_light(fd, &fput_needed); |
341 | if (!file) |
342 | goto out; |
343 | |
344 | i_mode = file->f_path.dentry->d_inode->i_mode; |
345 | ret = -ESPIPE; |
346 | if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && |
347 | !S_ISLNK(i_mode)) |
348 | goto out_put; |
349 | |
350 | mapping = file->f_mapping; |
351 | if (!mapping) { |
352 | ret = -EINVAL; |
353 | goto out_put; |
354 | } |
355 | |
356 | ret = 0; |
357 | if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { |
358 | ret = filemap_fdatawait_range(mapping, offset, endbyte); |
359 | if (ret < 0) |
360 | goto out_put; |
361 | } |
362 | |
363 | if (flags & SYNC_FILE_RANGE_WRITE) { |
364 | ret = filemap_fdatawrite_range(mapping, offset, endbyte); |
365 | if (ret < 0) |
366 | goto out_put; |
367 | } |
368 | |
369 | if (flags & SYNC_FILE_RANGE_WAIT_AFTER) |
370 | ret = filemap_fdatawait_range(mapping, offset, endbyte); |
371 | |
372 | out_put: |
373 | fput_light(file, fput_needed); |
374 | out: |
375 | return ret; |
376 | } |
377 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
378 | asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes, |
379 | long flags) |
380 | { |
381 | return SYSC_sync_file_range((int) fd, offset, nbytes, |
382 | (unsigned int) flags); |
383 | } |
384 | SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range); |
385 | #endif |
386 | |
387 | /* It would be nice if people remember that not all the world's an i386 |
388 | when they introduce new system calls */ |
389 | SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags, |
390 | loff_t offset, loff_t nbytes) |
391 | { |
392 | return sys_sync_file_range(fd, offset, nbytes, flags); |
393 | } |
394 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
395 | asmlinkage long SyS_sync_file_range2(long fd, long flags, |
396 | loff_t offset, loff_t nbytes) |
397 | { |
398 | return SYSC_sync_file_range2((int) fd, (unsigned int) flags, |
399 | offset, nbytes); |
400 | } |
401 | SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2); |
402 | #endif |
403 |
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