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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/export.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/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 == &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, WB_REASON_SYNC); |
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)) |
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, WB_REASON_SYNC); |
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 | * sync a single super |
133 | */ |
134 | SYSCALL_DEFINE1(syncfs, int, fd) |
135 | { |
136 | struct file *file; |
137 | struct super_block *sb; |
138 | int ret; |
139 | int fput_needed; |
140 | |
141 | file = fget_light(fd, &fput_needed); |
142 | if (!file) |
143 | return -EBADF; |
144 | sb = file->f_dentry->d_sb; |
145 | |
146 | down_read(&sb->s_umount); |
147 | ret = sync_filesystem(sb); |
148 | up_read(&sb->s_umount); |
149 | |
150 | fput_light(file, fput_needed); |
151 | return ret; |
152 | } |
153 | |
154 | /** |
155 | * vfs_fsync_range - helper to sync a range of data & metadata to disk |
156 | * @file: file to sync |
157 | * @start: offset in bytes of the beginning of data range to sync |
158 | * @end: offset in bytes of the end of data range (inclusive) |
159 | * @datasync: perform only datasync |
160 | * |
161 | * Write back data in range @start..@end and metadata for @file to disk. If |
162 | * @datasync is set only metadata needed to access modified file data is |
163 | * written. |
164 | */ |
165 | int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) |
166 | { |
167 | if (!file->f_op || !file->f_op->fsync) |
168 | return -EINVAL; |
169 | return file->f_op->fsync(file, start, end, datasync); |
170 | } |
171 | EXPORT_SYMBOL(vfs_fsync_range); |
172 | |
173 | /** |
174 | * vfs_fsync - perform a fsync or fdatasync on a file |
175 | * @file: file to sync |
176 | * @datasync: only perform a fdatasync operation |
177 | * |
178 | * Write back data and metadata for @file to disk. If @datasync is |
179 | * set only metadata needed to access modified file data is written. |
180 | */ |
181 | int vfs_fsync(struct file *file, int datasync) |
182 | { |
183 | return vfs_fsync_range(file, 0, LLONG_MAX, datasync); |
184 | } |
185 | EXPORT_SYMBOL(vfs_fsync); |
186 | |
187 | static int do_fsync(unsigned int fd, int datasync) |
188 | { |
189 | struct file *file; |
190 | int ret = -EBADF; |
191 | int fput_needed; |
192 | |
193 | file = fget_light(fd, &fput_needed); |
194 | if (file) { |
195 | ret = vfs_fsync(file, datasync); |
196 | fput_light(file, fput_needed); |
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 |
384 |
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