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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, WB_REASON_SYNC); | |
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, WB_REASON_SYNC); | |
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 | if (!file->f_op || !file->f_op->fsync) | |
169 | return -EINVAL; | |
170 | return file->f_op->fsync(file, start, end, datasync); | |
171 | } | |
172 | EXPORT_SYMBOL(vfs_fsync_range); | |
173 | ||
174 | /** | |
175 | * vfs_fsync - perform a fsync or fdatasync on a file | |
176 | * @file: file to sync | |
177 | * @datasync: only perform a fdatasync operation | |
178 | * | |
179 | * Write back data and metadata for @file to disk. If @datasync is | |
180 | * set only metadata needed to access modified file data is written. | |
181 | */ | |
182 | int vfs_fsync(struct file *file, int datasync) | |
183 | { | |
184 | return vfs_fsync_range(file, 0, LLONG_MAX, datasync); | |
185 | } | |
186 | EXPORT_SYMBOL(vfs_fsync); | |
187 | ||
188 | static int do_fsync(unsigned int fd, int datasync) | |
189 | { | |
190 | struct file *file; | |
191 | int ret = -EBADF; | |
192 | ||
193 | file = fget(fd); | |
194 | if (file) { | |
195 | ret = vfs_fsync(file, datasync); | |
196 | fput(file); | |
197 | } | |
198 | return ret; | |
199 | } | |
200 | ||
201 | SYSCALL_DEFINE1(fsync, unsigned int, fd) | |
202 | { | |
203 | return do_fsync(fd, 0); | |
204 | } | |
205 | ||
206 | SYSCALL_DEFINE1(fdatasync, unsigned int, fd) | |
207 | { | |
208 | return do_fsync(fd, 1); | |
209 | } | |
210 | ||
211 | /** | |
212 | * generic_write_sync - perform syncing after a write if file / inode is sync | |
213 | * @file: file to which the write happened | |
214 | * @pos: offset where the write started | |
215 | * @count: length of the write | |
216 | * | |
217 | * This is just a simple wrapper about our general syncing function. | |
218 | */ | |
219 | int generic_write_sync(struct file *file, loff_t pos, loff_t count) | |
220 | { | |
221 | if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host)) | |
222 | return 0; | |
223 | return vfs_fsync_range(file, pos, pos + count - 1, | |
224 | (file->f_flags & __O_SYNC) ? 0 : 1); | |
225 | } | |
226 | EXPORT_SYMBOL(generic_write_sync); | |
227 | ||
228 | /* | |
229 | * sys_sync_file_range() permits finely controlled syncing over a segment of | |
230 | * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is | |
231 | * zero then sys_sync_file_range() will operate from offset out to EOF. | |
232 | * | |
233 | * The flag bits are: | |
234 | * | |
235 | * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range | |
236 | * before performing the write. | |
237 | * | |
238 | * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the | |
239 | * range which are not presently under writeback. Note that this may block for | |
240 | * significant periods due to exhaustion of disk request structures. | |
241 | * | |
242 | * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range | |
243 | * after performing the write. | |
244 | * | |
245 | * Useful combinations of the flag bits are: | |
246 | * | |
247 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages | |
248 | * in the range which were dirty on entry to sys_sync_file_range() are placed | |
249 | * under writeout. This is a start-write-for-data-integrity operation. | |
250 | * | |
251 | * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which | |
252 | * are not presently under writeout. This is an asynchronous flush-to-disk | |
253 | * operation. Not suitable for data integrity operations. | |
254 | * | |
255 | * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for | |
256 | * completion of writeout of all pages in the range. This will be used after an | |
257 | * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait | |
258 | * for that operation to complete and to return the result. | |
259 | * | |
260 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: | |
261 | * a traditional sync() operation. This is a write-for-data-integrity operation | |
262 | * which will ensure that all pages in the range which were dirty on entry to | |
263 | * sys_sync_file_range() are committed to disk. | |
264 | * | |
265 | * | |
266 | * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any | |
267 | * I/O errors or ENOSPC conditions and will return those to the caller, after | |
268 | * clearing the EIO and ENOSPC flags in the address_space. | |
269 | * | |
270 | * It should be noted that none of these operations write out the file's | |
271 | * metadata. So unless the application is strictly performing overwrites of | |
272 | * already-instantiated disk blocks, there are no guarantees here that the data | |
273 | * will be available after a crash. | |
274 | */ | |
275 | SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes, | |
276 | unsigned int flags) | |
277 | { | |
278 | int ret; | |
279 | struct file *file; | |
280 | struct address_space *mapping; | |
281 | loff_t endbyte; /* inclusive */ | |
282 | int fput_needed; | |
283 | umode_t i_mode; | |
284 | ||
285 | ret = -EINVAL; | |
286 | if (flags & ~VALID_FLAGS) | |
287 | goto out; | |
288 | ||
289 | endbyte = offset + nbytes; | |
290 | ||
291 | if ((s64)offset < 0) | |
292 | goto out; | |
293 | if ((s64)endbyte < 0) | |
294 | goto out; | |
295 | if (endbyte < offset) | |
296 | goto out; | |
297 | ||
298 | if (sizeof(pgoff_t) == 4) { | |
299 | if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { | |
300 | /* | |
301 | * The range starts outside a 32 bit machine's | |
302 | * pagecache addressing capabilities. Let it "succeed" | |
303 | */ | |
304 | ret = 0; | |
305 | goto out; | |
306 | } | |
307 | if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { | |
308 | /* | |
309 | * Out to EOF | |
310 | */ | |
311 | nbytes = 0; | |
312 | } | |
313 | } | |
314 | ||
315 | if (nbytes == 0) | |
316 | endbyte = LLONG_MAX; | |
317 | else | |
318 | endbyte--; /* inclusive */ | |
319 | ||
320 | ret = -EBADF; | |
321 | file = fget_light(fd, &fput_needed); | |
322 | if (!file) | |
323 | goto out; | |
324 | ||
325 | i_mode = file->f_path.dentry->d_inode->i_mode; | |
326 | ret = -ESPIPE; | |
327 | if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && | |
328 | !S_ISLNK(i_mode)) | |
329 | goto out_put; | |
330 | ||
331 | mapping = file->f_mapping; | |
332 | if (!mapping) { | |
333 | ret = -EINVAL; | |
334 | goto out_put; | |
335 | } | |
336 | ||
337 | ret = 0; | |
338 | if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { | |
339 | ret = filemap_fdatawait_range(mapping, offset, endbyte); | |
340 | if (ret < 0) | |
341 | goto out_put; | |
342 | } | |
343 | ||
344 | if (flags & SYNC_FILE_RANGE_WRITE) { | |
345 | ret = filemap_fdatawrite_range(mapping, offset, endbyte); | |
346 | if (ret < 0) | |
347 | goto out_put; | |
348 | } | |
349 | ||
350 | if (flags & SYNC_FILE_RANGE_WAIT_AFTER) | |
351 | ret = filemap_fdatawait_range(mapping, offset, endbyte); | |
352 | ||
353 | out_put: | |
354 | fput_light(file, fput_needed); | |
355 | out: | |
356 | return ret; | |
357 | } | |
358 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS | |
359 | asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes, | |
360 | long flags) | |
361 | { | |
362 | return SYSC_sync_file_range((int) fd, offset, nbytes, | |
363 | (unsigned int) flags); | |
364 | } | |
365 | SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range); | |
366 | #endif | |
367 | ||
368 | /* It would be nice if people remember that not all the world's an i386 | |
369 | when they introduce new system calls */ | |
370 | SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags, | |
371 | loff_t offset, loff_t nbytes) | |
372 | { | |
373 | return sys_sync_file_range(fd, offset, nbytes, flags); | |
374 | } | |
375 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS | |
376 | asmlinkage long SyS_sync_file_range2(long fd, long flags, | |
377 | loff_t offset, loff_t nbytes) | |
378 | { | |
379 | return SYSC_sync_file_range2((int) fd, (unsigned int) flags, | |
380 | offset, nbytes); | |
381 | } | |
382 | SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2); | |
383 | #endif |