]>
Commit | Line | Data |
---|---|---|
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 | static void sync_one_sb(struct super_block *sb, void *arg) | |
81 | { | |
82 | if (!(sb->s_flags & MS_RDONLY) && sb->s_bdi) | |
83 | __sync_filesystem(sb, *(int *)arg); | |
84 | } | |
85 | /* | |
86 | * Sync all the data for all the filesystems (called by sys_sync() and | |
87 | * emergency sync) | |
88 | */ | |
89 | static void sync_filesystems(int wait) | |
90 | { | |
91 | iterate_supers(sync_one_sb, &wait); | |
92 | } | |
93 | ||
94 | /* | |
95 | * sync everything. Start out by waking pdflush, because that writes back | |
96 | * all queues in parallel. | |
97 | */ | |
98 | SYSCALL_DEFINE0(sync) | |
99 | { | |
100 | wakeup_flusher_threads(0); | |
101 | sync_filesystems(0); | |
102 | sync_filesystems(1); | |
103 | if (unlikely(laptop_mode)) | |
104 | laptop_sync_completion(); | |
105 | return 0; | |
106 | } | |
107 | ||
108 | static void do_sync_work(struct work_struct *work) | |
109 | { | |
110 | /* | |
111 | * Sync twice to reduce the possibility we skipped some inodes / pages | |
112 | * because they were temporarily locked | |
113 | */ | |
114 | sync_filesystems(0); | |
115 | sync_filesystems(0); | |
116 | printk("Emergency Sync complete\n"); | |
117 | kfree(work); | |
118 | } | |
119 | ||
120 | void emergency_sync(void) | |
121 | { | |
122 | struct work_struct *work; | |
123 | ||
124 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
125 | if (work) { | |
126 | INIT_WORK(work, do_sync_work); | |
127 | schedule_work(work); | |
128 | } | |
129 | } | |
130 | ||
131 | /** | |
132 | * vfs_fsync_range - helper to sync a range of data & metadata to disk | |
133 | * @file: file to sync | |
134 | * @start: offset in bytes of the beginning of data range to sync | |
135 | * @end: offset in bytes of the end of data range (inclusive) | |
136 | * @datasync: perform only datasync | |
137 | * | |
138 | * Write back data in range @start..@end and metadata for @file to disk. If | |
139 | * @datasync is set only metadata needed to access modified file data is | |
140 | * written. | |
141 | */ | |
142 | int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) | |
143 | { | |
144 | struct address_space *mapping = file->f_mapping; | |
145 | int err, ret; | |
146 | ||
147 | if (!file->f_op || !file->f_op->fsync) { | |
148 | ret = -EINVAL; | |
149 | goto out; | |
150 | } | |
151 | ||
152 | ret = filemap_write_and_wait_range(mapping, start, end); | |
153 | ||
154 | /* | |
155 | * We need to protect against concurrent writers, which could cause | |
156 | * livelocks in fsync_buffers_list(). | |
157 | */ | |
158 | mutex_lock(&mapping->host->i_mutex); | |
159 | err = file->f_op->fsync(file, datasync); | |
160 | if (!ret) | |
161 | ret = err; | |
162 | mutex_unlock(&mapping->host->i_mutex); | |
163 | ||
164 | out: | |
165 | return ret; | |
166 | } | |
167 | EXPORT_SYMBOL(vfs_fsync_range); | |
168 | ||
169 | /** | |
170 | * vfs_fsync - perform a fsync or fdatasync on a file | |
171 | * @file: file to sync | |
172 | * @datasync: only perform a fdatasync operation | |
173 | * | |
174 | * Write back data and metadata for @file to disk. If @datasync is | |
175 | * set only metadata needed to access modified file data is written. | |
176 | */ | |
177 | int vfs_fsync(struct file *file, int datasync) | |
178 | { | |
179 | return vfs_fsync_range(file, 0, LLONG_MAX, datasync); | |
180 | } | |
181 | EXPORT_SYMBOL(vfs_fsync); | |
182 | ||
183 | static int do_fsync(unsigned int fd, int datasync) | |
184 | { | |
185 | struct file *file; | |
186 | int ret = -EBADF; | |
187 | ||
188 | file = fget(fd); | |
189 | if (file) { | |
190 | ret = vfs_fsync(file, datasync); | |
191 | fput(file); | |
192 | } | |
193 | return ret; | |
194 | } | |
195 | ||
196 | SYSCALL_DEFINE1(fsync, unsigned int, fd) | |
197 | { | |
198 | return do_fsync(fd, 0); | |
199 | } | |
200 | ||
201 | SYSCALL_DEFINE1(fdatasync, unsigned int, fd) | |
202 | { | |
203 | return do_fsync(fd, 1); | |
204 | } | |
205 | ||
206 | /** | |
207 | * generic_write_sync - perform syncing after a write if file / inode is sync | |
208 | * @file: file to which the write happened | |
209 | * @pos: offset where the write started | |
210 | * @count: length of the write | |
211 | * | |
212 | * This is just a simple wrapper about our general syncing function. | |
213 | */ | |
214 | int generic_write_sync(struct file *file, loff_t pos, loff_t count) | |
215 | { | |
216 | if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host)) | |
217 | return 0; | |
218 | return vfs_fsync_range(file, pos, pos + count - 1, | |
219 | (file->f_flags & __O_SYNC) ? 0 : 1); | |
220 | } | |
221 | EXPORT_SYMBOL(generic_write_sync); | |
222 | ||
223 | /* | |
224 | * sys_sync_file_range() permits finely controlled syncing over a segment of | |
225 | * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is | |
226 | * zero then sys_sync_file_range() will operate from offset out to EOF. | |
227 | * | |
228 | * The flag bits are: | |
229 | * | |
230 | * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range | |
231 | * before performing the write. | |
232 | * | |
233 | * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the | |
234 | * range which are not presently under writeback. Note that this may block for | |
235 | * significant periods due to exhaustion of disk request structures. | |
236 | * | |
237 | * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range | |
238 | * after performing the write. | |
239 | * | |
240 | * Useful combinations of the flag bits are: | |
241 | * | |
242 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages | |
243 | * in the range which were dirty on entry to sys_sync_file_range() are placed | |
244 | * under writeout. This is a start-write-for-data-integrity operation. | |
245 | * | |
246 | * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which | |
247 | * are not presently under writeout. This is an asynchronous flush-to-disk | |
248 | * operation. Not suitable for data integrity operations. | |
249 | * | |
250 | * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for | |
251 | * completion of writeout of all pages in the range. This will be used after an | |
252 | * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait | |
253 | * for that operation to complete and to return the result. | |
254 | * | |
255 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: | |
256 | * a traditional sync() operation. This is a write-for-data-integrity operation | |
257 | * which will ensure that all pages in the range which were dirty on entry to | |
258 | * sys_sync_file_range() are committed to disk. | |
259 | * | |
260 | * | |
261 | * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any | |
262 | * I/O errors or ENOSPC conditions and will return those to the caller, after | |
263 | * clearing the EIO and ENOSPC flags in the address_space. | |
264 | * | |
265 | * It should be noted that none of these operations write out the file's | |
266 | * metadata. So unless the application is strictly performing overwrites of | |
267 | * already-instantiated disk blocks, there are no guarantees here that the data | |
268 | * will be available after a crash. | |
269 | */ | |
270 | SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes, | |
271 | unsigned int flags) | |
272 | { | |
273 | int ret; | |
274 | struct file *file; | |
275 | struct address_space *mapping; | |
276 | loff_t endbyte; /* inclusive */ | |
277 | int fput_needed; | |
278 | umode_t i_mode; | |
279 | ||
280 | ret = -EINVAL; | |
281 | if (flags & ~VALID_FLAGS) | |
282 | goto out; | |
283 | ||
284 | endbyte = offset + nbytes; | |
285 | ||
286 | if ((s64)offset < 0) | |
287 | goto out; | |
288 | if ((s64)endbyte < 0) | |
289 | goto out; | |
290 | if (endbyte < offset) | |
291 | goto out; | |
292 | ||
293 | if (sizeof(pgoff_t) == 4) { | |
294 | if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { | |
295 | /* | |
296 | * The range starts outside a 32 bit machine's | |
297 | * pagecache addressing capabilities. Let it "succeed" | |
298 | */ | |
299 | ret = 0; | |
300 | goto out; | |
301 | } | |
302 | if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { | |
303 | /* | |
304 | * Out to EOF | |
305 | */ | |
306 | nbytes = 0; | |
307 | } | |
308 | } | |
309 | ||
310 | if (nbytes == 0) | |
311 | endbyte = LLONG_MAX; | |
312 | else | |
313 | endbyte--; /* inclusive */ | |
314 | ||
315 | ret = -EBADF; | |
316 | file = fget_light(fd, &fput_needed); | |
317 | if (!file) | |
318 | goto out; | |
319 | ||
320 | i_mode = file->f_path.dentry->d_inode->i_mode; | |
321 | ret = -ESPIPE; | |
322 | if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && | |
323 | !S_ISLNK(i_mode)) | |
324 | goto out_put; | |
325 | ||
326 | mapping = file->f_mapping; | |
327 | if (!mapping) { | |
328 | ret = -EINVAL; | |
329 | goto out_put; | |
330 | } | |
331 | ||
332 | ret = 0; | |
333 | if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { | |
334 | ret = filemap_fdatawait_range(mapping, offset, endbyte); | |
335 | if (ret < 0) | |
336 | goto out_put; | |
337 | } | |
338 | ||
339 | if (flags & SYNC_FILE_RANGE_WRITE) { | |
340 | ret = filemap_fdatawrite_range(mapping, offset, endbyte); | |
341 | if (ret < 0) | |
342 | goto out_put; | |
343 | } | |
344 | ||
345 | if (flags & SYNC_FILE_RANGE_WAIT_AFTER) | |
346 | ret = filemap_fdatawait_range(mapping, offset, endbyte); | |
347 | ||
348 | out_put: | |
349 | fput_light(file, fput_needed); | |
350 | out: | |
351 | return ret; | |
352 | } | |
353 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS | |
354 | asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes, | |
355 | long flags) | |
356 | { | |
357 | return SYSC_sync_file_range((int) fd, offset, nbytes, | |
358 | (unsigned int) flags); | |
359 | } | |
360 | SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range); | |
361 | #endif | |
362 | ||
363 | /* It would be nice if people remember that not all the world's an i386 | |
364 | when they introduce new system calls */ | |
365 | SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags, | |
366 | loff_t offset, loff_t nbytes) | |
367 | { | |
368 | return sys_sync_file_range(fd, offset, nbytes, flags); | |
369 | } | |
370 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS | |
371 | asmlinkage long SyS_sync_file_range2(long fd, long flags, | |
372 | loff_t offset, loff_t nbytes) | |
373 | { | |
374 | return SYSC_sync_file_range2((int) fd, (unsigned int) flags, | |
375 | offset, nbytes); | |
376 | } | |
377 | SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2); | |
378 | #endif |