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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 | if (wait) |
33 | sync_inodes_sb(sb); |
34 | else |
35 | writeback_inodes_sb(sb, WB_REASON_SYNC); |
36 | |
37 | if (sb->s_op->sync_fs) |
38 | sb->s_op->sync_fs(sb, wait); |
39 | return __sync_blockdev(sb->s_bdev, wait); |
40 | } |
41 | |
42 | /* |
43 | * Write out and wait upon all dirty data associated with this |
44 | * superblock. Filesystem data as well as the underlying block |
45 | * device. Takes the superblock lock. |
46 | */ |
47 | int sync_filesystem(struct super_block *sb) |
48 | { |
49 | int ret; |
50 | |
51 | /* |
52 | * We need to be protected against the filesystem going from |
53 | * r/o to r/w or vice versa. |
54 | */ |
55 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
56 | |
57 | /* |
58 | * No point in syncing out anything if the filesystem is read-only. |
59 | */ |
60 | if (sb->s_flags & MS_RDONLY) |
61 | return 0; |
62 | |
63 | ret = __sync_filesystem(sb, 0); |
64 | if (ret < 0) |
65 | return ret; |
66 | return __sync_filesystem(sb, 1); |
67 | } |
68 | EXPORT_SYMBOL_GPL(sync_filesystem); |
69 | |
70 | static void sync_inodes_one_sb(struct super_block *sb, void *arg) |
71 | { |
72 | if (!(sb->s_flags & MS_RDONLY)) |
73 | sync_inodes_sb(sb); |
74 | } |
75 | |
76 | static void sync_fs_one_sb(struct super_block *sb, void *arg) |
77 | { |
78 | if (!(sb->s_flags & MS_RDONLY) && sb->s_op->sync_fs) |
79 | sb->s_op->sync_fs(sb, *(int *)arg); |
80 | } |
81 | |
82 | static void fdatawrite_one_bdev(struct block_device *bdev, void *arg) |
83 | { |
84 | filemap_fdatawrite(bdev->bd_inode->i_mapping); |
85 | } |
86 | |
87 | static void fdatawait_one_bdev(struct block_device *bdev, void *arg) |
88 | { |
89 | filemap_fdatawait(bdev->bd_inode->i_mapping); |
90 | } |
91 | |
92 | /* |
93 | * Sync everything. We start by waking flusher threads so that most of |
94 | * writeback runs on all devices in parallel. Then we sync all inodes reliably |
95 | * which effectively also waits for all flusher threads to finish doing |
96 | * writeback. At this point all data is on disk so metadata should be stable |
97 | * and we tell filesystems to sync their metadata via ->sync_fs() calls. |
98 | * Finally, we writeout all block devices because some filesystems (e.g. ext2) |
99 | * just write metadata (such as inodes or bitmaps) to block device page cache |
100 | * and do not sync it on their own in ->sync_fs(). |
101 | */ |
102 | SYSCALL_DEFINE0(sync) |
103 | { |
104 | int nowait = 0, wait = 1; |
105 | |
106 | wakeup_flusher_threads(0, WB_REASON_SYNC); |
107 | iterate_supers(sync_inodes_one_sb, NULL); |
108 | iterate_supers(sync_fs_one_sb, &nowait); |
109 | iterate_supers(sync_fs_one_sb, &wait); |
110 | iterate_bdevs(fdatawrite_one_bdev, NULL); |
111 | iterate_bdevs(fdatawait_one_bdev, NULL); |
112 | if (unlikely(laptop_mode)) |
113 | laptop_sync_completion(); |
114 | return 0; |
115 | } |
116 | |
117 | static void do_sync_work(struct work_struct *work) |
118 | { |
119 | int nowait = 0; |
120 | |
121 | /* |
122 | * Sync twice to reduce the possibility we skipped some inodes / pages |
123 | * because they were temporarily locked |
124 | */ |
125 | iterate_supers(sync_inodes_one_sb, &nowait); |
126 | iterate_supers(sync_fs_one_sb, &nowait); |
127 | iterate_bdevs(fdatawrite_one_bdev, NULL); |
128 | iterate_supers(sync_inodes_one_sb, &nowait); |
129 | iterate_supers(sync_fs_one_sb, &nowait); |
130 | iterate_bdevs(fdatawrite_one_bdev, NULL); |
131 | printk("Emergency Sync complete\n"); |
132 | kfree(work); |
133 | } |
134 | |
135 | void emergency_sync(void) |
136 | { |
137 | struct work_struct *work; |
138 | |
139 | work = kmalloc(sizeof(*work), GFP_ATOMIC); |
140 | if (work) { |
141 | INIT_WORK(work, do_sync_work); |
142 | schedule_work(work); |
143 | } |
144 | } |
145 | |
146 | /* |
147 | * sync a single super |
148 | */ |
149 | SYSCALL_DEFINE1(syncfs, int, fd) |
150 | { |
151 | struct fd f = fdget(fd); |
152 | struct super_block *sb; |
153 | int ret; |
154 | |
155 | if (!f.file) |
156 | return -EBADF; |
157 | sb = f.file->f_dentry->d_sb; |
158 | |
159 | down_read(&sb->s_umount); |
160 | ret = sync_filesystem(sb); |
161 | up_read(&sb->s_umount); |
162 | |
163 | fdput(f); |
164 | return ret; |
165 | } |
166 | |
167 | /** |
168 | * vfs_fsync_range - helper to sync a range of data & metadata to disk |
169 | * @file: file to sync |
170 | * @start: offset in bytes of the beginning of data range to sync |
171 | * @end: offset in bytes of the end of data range (inclusive) |
172 | * @datasync: perform only datasync |
173 | * |
174 | * Write back data in range @start..@end and metadata for @file to disk. If |
175 | * @datasync is set only metadata needed to access modified file data is |
176 | * written. |
177 | */ |
178 | int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) |
179 | { |
180 | if (!file->f_op || !file->f_op->fsync) |
181 | return -EINVAL; |
182 | return file->f_op->fsync(file, start, end, datasync); |
183 | } |
184 | EXPORT_SYMBOL(vfs_fsync_range); |
185 | |
186 | /** |
187 | * vfs_fsync - perform a fsync or fdatasync on a file |
188 | * @file: file to sync |
189 | * @datasync: only perform a fdatasync operation |
190 | * |
191 | * Write back data and metadata for @file to disk. If @datasync is |
192 | * set only metadata needed to access modified file data is written. |
193 | */ |
194 | int vfs_fsync(struct file *file, int datasync) |
195 | { |
196 | return vfs_fsync_range(file, 0, LLONG_MAX, datasync); |
197 | } |
198 | EXPORT_SYMBOL(vfs_fsync); |
199 | |
200 | static int do_fsync(unsigned int fd, int datasync) |
201 | { |
202 | struct fd f = fdget(fd); |
203 | int ret = -EBADF; |
204 | |
205 | if (f.file) { |
206 | ret = vfs_fsync(f.file, datasync); |
207 | fdput(f); |
208 | } |
209 | return ret; |
210 | } |
211 | |
212 | SYSCALL_DEFINE1(fsync, unsigned int, fd) |
213 | { |
214 | return do_fsync(fd, 0); |
215 | } |
216 | |
217 | SYSCALL_DEFINE1(fdatasync, unsigned int, fd) |
218 | { |
219 | return do_fsync(fd, 1); |
220 | } |
221 | |
222 | /** |
223 | * generic_write_sync - perform syncing after a write if file / inode is sync |
224 | * @file: file to which the write happened |
225 | * @pos: offset where the write started |
226 | * @count: length of the write |
227 | * |
228 | * This is just a simple wrapper about our general syncing function. |
229 | */ |
230 | int generic_write_sync(struct file *file, loff_t pos, loff_t count) |
231 | { |
232 | if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host)) |
233 | return 0; |
234 | return vfs_fsync_range(file, pos, pos + count - 1, |
235 | (file->f_flags & __O_SYNC) ? 0 : 1); |
236 | } |
237 | EXPORT_SYMBOL(generic_write_sync); |
238 | |
239 | /* |
240 | * sys_sync_file_range() permits finely controlled syncing over a segment of |
241 | * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is |
242 | * zero then sys_sync_file_range() will operate from offset out to EOF. |
243 | * |
244 | * The flag bits are: |
245 | * |
246 | * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range |
247 | * before performing the write. |
248 | * |
249 | * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the |
250 | * range which are not presently under writeback. Note that this may block for |
251 | * significant periods due to exhaustion of disk request structures. |
252 | * |
253 | * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range |
254 | * after performing the write. |
255 | * |
256 | * Useful combinations of the flag bits are: |
257 | * |
258 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages |
259 | * in the range which were dirty on entry to sys_sync_file_range() are placed |
260 | * under writeout. This is a start-write-for-data-integrity operation. |
261 | * |
262 | * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which |
263 | * are not presently under writeout. This is an asynchronous flush-to-disk |
264 | * operation. Not suitable for data integrity operations. |
265 | * |
266 | * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for |
267 | * completion of writeout of all pages in the range. This will be used after an |
268 | * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait |
269 | * for that operation to complete and to return the result. |
270 | * |
271 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: |
272 | * a traditional sync() operation. This is a write-for-data-integrity operation |
273 | * which will ensure that all pages in the range which were dirty on entry to |
274 | * sys_sync_file_range() are committed to disk. |
275 | * |
276 | * |
277 | * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any |
278 | * I/O errors or ENOSPC conditions and will return those to the caller, after |
279 | * clearing the EIO and ENOSPC flags in the address_space. |
280 | * |
281 | * It should be noted that none of these operations write out the file's |
282 | * metadata. So unless the application is strictly performing overwrites of |
283 | * already-instantiated disk blocks, there are no guarantees here that the data |
284 | * will be available after a crash. |
285 | */ |
286 | SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes, |
287 | unsigned int, flags) |
288 | { |
289 | int ret; |
290 | struct fd f; |
291 | struct address_space *mapping; |
292 | loff_t endbyte; /* inclusive */ |
293 | umode_t i_mode; |
294 | |
295 | ret = -EINVAL; |
296 | if (flags & ~VALID_FLAGS) |
297 | goto out; |
298 | |
299 | endbyte = offset + nbytes; |
300 | |
301 | if ((s64)offset < 0) |
302 | goto out; |
303 | if ((s64)endbyte < 0) |
304 | goto out; |
305 | if (endbyte < offset) |
306 | goto out; |
307 | |
308 | if (sizeof(pgoff_t) == 4) { |
309 | if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { |
310 | /* |
311 | * The range starts outside a 32 bit machine's |
312 | * pagecache addressing capabilities. Let it "succeed" |
313 | */ |
314 | ret = 0; |
315 | goto out; |
316 | } |
317 | if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { |
318 | /* |
319 | * Out to EOF |
320 | */ |
321 | nbytes = 0; |
322 | } |
323 | } |
324 | |
325 | if (nbytes == 0) |
326 | endbyte = LLONG_MAX; |
327 | else |
328 | endbyte--; /* inclusive */ |
329 | |
330 | ret = -EBADF; |
331 | f = fdget(fd); |
332 | if (!f.file) |
333 | goto out; |
334 | |
335 | i_mode = file_inode(f.file)->i_mode; |
336 | ret = -ESPIPE; |
337 | if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && |
338 | !S_ISLNK(i_mode)) |
339 | goto out_put; |
340 | |
341 | mapping = f.file->f_mapping; |
342 | if (!mapping) { |
343 | ret = -EINVAL; |
344 | goto out_put; |
345 | } |
346 | |
347 | ret = 0; |
348 | if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { |
349 | ret = filemap_fdatawait_range(mapping, offset, endbyte); |
350 | if (ret < 0) |
351 | goto out_put; |
352 | } |
353 | |
354 | if (flags & SYNC_FILE_RANGE_WRITE) { |
355 | ret = filemap_fdatawrite_range(mapping, offset, endbyte); |
356 | if (ret < 0) |
357 | goto out_put; |
358 | } |
359 | |
360 | if (flags & SYNC_FILE_RANGE_WAIT_AFTER) |
361 | ret = filemap_fdatawait_range(mapping, offset, endbyte); |
362 | |
363 | out_put: |
364 | fdput(f); |
365 | out: |
366 | return ret; |
367 | } |
368 | |
369 | /* It would be nice if people remember that not all the world's an i386 |
370 | when they introduce new system calls */ |
371 | SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags, |
372 | loff_t, offset, loff_t, nbytes) |
373 | { |
374 | return sys_sync_file_range(fd, offset, nbytes, flags); |
375 | } |
376 |
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