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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->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 | * sys_sync_file_range() permits finely controlled syncing over a segment of | |
224 | * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is | |
225 | * zero then sys_sync_file_range() will operate from offset out to EOF. | |
226 | * | |
227 | * The flag bits are: | |
228 | * | |
229 | * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range | |
230 | * before performing the write. | |
231 | * | |
232 | * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the | |
233 | * range which are not presently under writeback. Note that this may block for | |
234 | * significant periods due to exhaustion of disk request structures. | |
235 | * | |
236 | * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range | |
237 | * after performing the write. | |
238 | * | |
239 | * Useful combinations of the flag bits are: | |
240 | * | |
241 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages | |
242 | * in the range which were dirty on entry to sys_sync_file_range() are placed | |
243 | * under writeout. This is a start-write-for-data-integrity operation. | |
244 | * | |
245 | * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which | |
246 | * are not presently under writeout. This is an asynchronous flush-to-disk | |
247 | * operation. Not suitable for data integrity operations. | |
248 | * | |
249 | * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for | |
250 | * completion of writeout of all pages in the range. This will be used after an | |
251 | * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait | |
252 | * for that operation to complete and to return the result. | |
253 | * | |
254 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: | |
255 | * a traditional sync() operation. This is a write-for-data-integrity operation | |
256 | * which will ensure that all pages in the range which were dirty on entry to | |
257 | * sys_sync_file_range() are committed to disk. | |
258 | * | |
259 | * | |
260 | * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any | |
261 | * I/O errors or ENOSPC conditions and will return those to the caller, after | |
262 | * clearing the EIO and ENOSPC flags in the address_space. | |
263 | * | |
264 | * It should be noted that none of these operations write out the file's | |
265 | * metadata. So unless the application is strictly performing overwrites of | |
266 | * already-instantiated disk blocks, there are no guarantees here that the data | |
267 | * will be available after a crash. | |
268 | */ | |
269 | SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes, | |
270 | unsigned int, flags) | |
271 | { | |
272 | int ret; | |
273 | struct fd f; | |
274 | struct address_space *mapping; | |
275 | loff_t endbyte; /* inclusive */ | |
276 | umode_t i_mode; | |
277 | ||
278 | ret = -EINVAL; | |
279 | if (flags & ~VALID_FLAGS) | |
280 | goto out; | |
281 | ||
282 | endbyte = offset + nbytes; | |
283 | ||
284 | if ((s64)offset < 0) | |
285 | goto out; | |
286 | if ((s64)endbyte < 0) | |
287 | goto out; | |
288 | if (endbyte < offset) | |
289 | goto out; | |
290 | ||
291 | if (sizeof(pgoff_t) == 4) { | |
292 | if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { | |
293 | /* | |
294 | * The range starts outside a 32 bit machine's | |
295 | * pagecache addressing capabilities. Let it "succeed" | |
296 | */ | |
297 | ret = 0; | |
298 | goto out; | |
299 | } | |
300 | if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) { | |
301 | /* | |
302 | * Out to EOF | |
303 | */ | |
304 | nbytes = 0; | |
305 | } | |
306 | } | |
307 | ||
308 | if (nbytes == 0) | |
309 | endbyte = LLONG_MAX; | |
310 | else | |
311 | endbyte--; /* inclusive */ | |
312 | ||
313 | ret = -EBADF; | |
314 | f = fdget(fd); | |
315 | if (!f.file) | |
316 | goto out; | |
317 | ||
318 | i_mode = file_inode(f.file)->i_mode; | |
319 | ret = -ESPIPE; | |
320 | if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && | |
321 | !S_ISLNK(i_mode)) | |
322 | goto out_put; | |
323 | ||
324 | mapping = f.file->f_mapping; | |
325 | if (!mapping) { | |
326 | ret = -EINVAL; | |
327 | goto out_put; | |
328 | } | |
329 | ||
330 | ret = 0; | |
331 | if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { | |
332 | ret = filemap_fdatawait_range(mapping, offset, endbyte); | |
333 | if (ret < 0) | |
334 | goto out_put; | |
335 | } | |
336 | ||
337 | if (flags & SYNC_FILE_RANGE_WRITE) { | |
338 | ret = filemap_fdatawrite_range(mapping, offset, endbyte); | |
339 | if (ret < 0) | |
340 | goto out_put; | |
341 | } | |
342 | ||
343 | if (flags & SYNC_FILE_RANGE_WAIT_AFTER) | |
344 | ret = filemap_fdatawait_range(mapping, offset, endbyte); | |
345 | ||
346 | out_put: | |
347 | fdput(f); | |
348 | out: | |
349 | return ret; | |
350 | } | |
351 | ||
352 | /* It would be nice if people remember that not all the world's an i386 | |
353 | when they introduce new system calls */ | |
354 | SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags, | |
355 | loff_t, offset, loff_t, nbytes) | |
356 | { | |
357 | return sys_sync_file_range(fd, offset, nbytes, flags); | |
358 | } |