1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * High-level sync()-related operations |
4 | */ |
5 | |
6 | #include <linux/blkdev.h> |
7 | #include <linux/kernel.h> |
8 | #include <linux/file.h> |
9 | #include <linux/fs.h> |
10 | #include <linux/slab.h> |
11 | #include <linux/export.h> |
12 | #include <linux/namei.h> |
13 | #include <linux/sched.h> |
14 | #include <linux/writeback.h> |
15 | #include <linux/syscalls.h> |
16 | #include <linux/linkage.h> |
17 | #include <linux/pagemap.h> |
18 | #include <linux/quotaops.h> |
19 | #include <linux/backing-dev.h> |
20 | #include "internal.h" |
21 | |
22 | #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \ |
23 | SYNC_FILE_RANGE_WAIT_AFTER) |
24 | |
25 | /* |
26 | * Write out and wait upon all dirty data associated with this |
27 | * superblock. Filesystem data as well as the underlying block |
28 | * device. Takes the superblock lock. |
29 | */ |
30 | int sync_filesystem(struct super_block *sb) |
31 | { |
32 | int ret = 0; |
33 | |
34 | /* |
35 | * We need to be protected against the filesystem going from |
36 | * r/o to r/w or vice versa. |
37 | */ |
38 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
39 | |
40 | /* |
41 | * No point in syncing out anything if the filesystem is read-only. |
42 | */ |
43 | if (sb_rdonly(sb)) |
44 | return 0; |
45 | |
46 | /* |
47 | * Do the filesystem syncing work. For simple filesystems |
48 | * writeback_inodes_sb(sb) just dirties buffers with inodes so we have |
49 | * to submit I/O for these buffers via sync_blockdev(). This also |
50 | * speeds up the wait == 1 case since in that case write_inode() |
51 | * methods call sync_dirty_buffer() and thus effectively write one block |
52 | * at a time. |
53 | */ |
54 | writeback_inodes_sb(sb, reason: WB_REASON_SYNC); |
55 | if (sb->s_op->sync_fs) { |
56 | ret = sb->s_op->sync_fs(sb, 0); |
57 | if (ret) |
58 | return ret; |
59 | } |
60 | ret = sync_blockdev_nowait(bdev: sb->s_bdev); |
61 | if (ret) |
62 | return ret; |
63 | |
64 | sync_inodes_sb(sb); |
65 | if (sb->s_op->sync_fs) { |
66 | ret = sb->s_op->sync_fs(sb, 1); |
67 | if (ret) |
68 | return ret; |
69 | } |
70 | return sync_blockdev(bdev: sb->s_bdev); |
71 | } |
72 | EXPORT_SYMBOL(sync_filesystem); |
73 | |
74 | static void sync_inodes_one_sb(struct super_block *sb, void *arg) |
75 | { |
76 | if (!sb_rdonly(sb)) |
77 | sync_inodes_sb(sb); |
78 | } |
79 | |
80 | static void sync_fs_one_sb(struct super_block *sb, void *arg) |
81 | { |
82 | if (!sb_rdonly(sb) && !(sb->s_iflags & SB_I_SKIP_SYNC) && |
83 | sb->s_op->sync_fs) |
84 | sb->s_op->sync_fs(sb, *(int *)arg); |
85 | } |
86 | |
87 | /* |
88 | * Sync everything. We start by waking flusher threads so that most of |
89 | * writeback runs on all devices in parallel. Then we sync all inodes reliably |
90 | * which effectively also waits for all flusher threads to finish doing |
91 | * writeback. At this point all data is on disk so metadata should be stable |
92 | * and we tell filesystems to sync their metadata via ->sync_fs() calls. |
93 | * Finally, we writeout all block devices because some filesystems (e.g. ext2) |
94 | * just write metadata (such as inodes or bitmaps) to block device page cache |
95 | * and do not sync it on their own in ->sync_fs(). |
96 | */ |
97 | void ksys_sync(void) |
98 | { |
99 | int nowait = 0, wait = 1; |
100 | |
101 | wakeup_flusher_threads(reason: WB_REASON_SYNC); |
102 | iterate_supers(sync_inodes_one_sb, NULL); |
103 | iterate_supers(sync_fs_one_sb, &nowait); |
104 | iterate_supers(sync_fs_one_sb, &wait); |
105 | sync_bdevs(wait: false); |
106 | sync_bdevs(wait: true); |
107 | if (unlikely(laptop_mode)) |
108 | laptop_sync_completion(); |
109 | } |
110 | |
111 | SYSCALL_DEFINE0(sync) |
112 | { |
113 | ksys_sync(); |
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 | sync_bdevs(wait: false); |
128 | iterate_supers(sync_inodes_one_sb, &nowait); |
129 | iterate_supers(sync_fs_one_sb, &nowait); |
130 | sync_bdevs(wait: false); |
131 | printk("Emergency Sync complete\n" ); |
132 | kfree(objp: work); |
133 | } |
134 | |
135 | void emergency_sync(void) |
136 | { |
137 | struct work_struct *work; |
138 | |
139 | work = kmalloc(size: 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, ret2; |
154 | |
155 | if (!f.file) |
156 | return -EBADF; |
157 | sb = f.file->f_path.dentry->d_sb; |
158 | |
159 | down_read(sem: &sb->s_umount); |
160 | ret = sync_filesystem(sb); |
161 | up_read(sem: &sb->s_umount); |
162 | |
163 | ret2 = errseq_check_and_advance(eseq: &sb->s_wb_err, since: &f.file->f_sb_err); |
164 | |
165 | fdput(fd: f); |
166 | return ret ? ret : ret2; |
167 | } |
168 | |
169 | /** |
170 | * vfs_fsync_range - helper to sync a range of data & metadata to disk |
171 | * @file: file to sync |
172 | * @start: offset in bytes of the beginning of data range to sync |
173 | * @end: offset in bytes of the end of data range (inclusive) |
174 | * @datasync: perform only datasync |
175 | * |
176 | * Write back data in range @start..@end and metadata for @file to disk. If |
177 | * @datasync is set only metadata needed to access modified file data is |
178 | * written. |
179 | */ |
180 | int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync) |
181 | { |
182 | struct inode *inode = file->f_mapping->host; |
183 | |
184 | if (!file->f_op->fsync) |
185 | return -EINVAL; |
186 | if (!datasync && (inode->i_state & I_DIRTY_TIME)) |
187 | mark_inode_dirty_sync(inode); |
188 | return file->f_op->fsync(file, start, end, datasync); |
189 | } |
190 | EXPORT_SYMBOL(vfs_fsync_range); |
191 | |
192 | /** |
193 | * vfs_fsync - perform a fsync or fdatasync on a file |
194 | * @file: file to sync |
195 | * @datasync: only perform a fdatasync operation |
196 | * |
197 | * Write back data and metadata for @file to disk. If @datasync is |
198 | * set only metadata needed to access modified file data is written. |
199 | */ |
200 | int vfs_fsync(struct file *file, int datasync) |
201 | { |
202 | return vfs_fsync_range(file, 0, LLONG_MAX, datasync); |
203 | } |
204 | EXPORT_SYMBOL(vfs_fsync); |
205 | |
206 | static int do_fsync(unsigned int fd, int datasync) |
207 | { |
208 | struct fd f = fdget(fd); |
209 | int ret = -EBADF; |
210 | |
211 | if (f.file) { |
212 | ret = vfs_fsync(f.file, datasync); |
213 | fdput(fd: f); |
214 | } |
215 | return ret; |
216 | } |
217 | |
218 | SYSCALL_DEFINE1(fsync, unsigned int, fd) |
219 | { |
220 | return do_fsync(fd, datasync: 0); |
221 | } |
222 | |
223 | SYSCALL_DEFINE1(fdatasync, unsigned int, fd) |
224 | { |
225 | return do_fsync(fd, datasync: 1); |
226 | } |
227 | |
228 | int sync_file_range(struct file *file, loff_t offset, loff_t nbytes, |
229 | unsigned int flags) |
230 | { |
231 | int ret; |
232 | struct address_space *mapping; |
233 | loff_t endbyte; /* inclusive */ |
234 | umode_t i_mode; |
235 | |
236 | ret = -EINVAL; |
237 | if (flags & ~VALID_FLAGS) |
238 | goto out; |
239 | |
240 | endbyte = offset + nbytes; |
241 | |
242 | if ((s64)offset < 0) |
243 | goto out; |
244 | if ((s64)endbyte < 0) |
245 | goto out; |
246 | if (endbyte < offset) |
247 | goto out; |
248 | |
249 | if (sizeof(pgoff_t) == 4) { |
250 | if (offset >= (0x100000000ULL << PAGE_SHIFT)) { |
251 | /* |
252 | * The range starts outside a 32 bit machine's |
253 | * pagecache addressing capabilities. Let it "succeed" |
254 | */ |
255 | ret = 0; |
256 | goto out; |
257 | } |
258 | if (endbyte >= (0x100000000ULL << PAGE_SHIFT)) { |
259 | /* |
260 | * Out to EOF |
261 | */ |
262 | nbytes = 0; |
263 | } |
264 | } |
265 | |
266 | if (nbytes == 0) |
267 | endbyte = LLONG_MAX; |
268 | else |
269 | endbyte--; /* inclusive */ |
270 | |
271 | i_mode = file_inode(f: file)->i_mode; |
272 | ret = -ESPIPE; |
273 | if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) && |
274 | !S_ISLNK(i_mode)) |
275 | goto out; |
276 | |
277 | mapping = file->f_mapping; |
278 | ret = 0; |
279 | if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) { |
280 | ret = file_fdatawait_range(file, lstart: offset, lend: endbyte); |
281 | if (ret < 0) |
282 | goto out; |
283 | } |
284 | |
285 | if (flags & SYNC_FILE_RANGE_WRITE) { |
286 | int sync_mode = WB_SYNC_NONE; |
287 | |
288 | if ((flags & SYNC_FILE_RANGE_WRITE_AND_WAIT) == |
289 | SYNC_FILE_RANGE_WRITE_AND_WAIT) |
290 | sync_mode = WB_SYNC_ALL; |
291 | |
292 | ret = __filemap_fdatawrite_range(mapping, start: offset, end: endbyte, |
293 | sync_mode); |
294 | if (ret < 0) |
295 | goto out; |
296 | } |
297 | |
298 | if (flags & SYNC_FILE_RANGE_WAIT_AFTER) |
299 | ret = file_fdatawait_range(file, lstart: offset, lend: endbyte); |
300 | |
301 | out: |
302 | return ret; |
303 | } |
304 | |
305 | /* |
306 | * ksys_sync_file_range() permits finely controlled syncing over a segment of |
307 | * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is |
308 | * zero then ksys_sync_file_range() will operate from offset out to EOF. |
309 | * |
310 | * The flag bits are: |
311 | * |
312 | * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range |
313 | * before performing the write. |
314 | * |
315 | * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the |
316 | * range which are not presently under writeback. Note that this may block for |
317 | * significant periods due to exhaustion of disk request structures. |
318 | * |
319 | * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range |
320 | * after performing the write. |
321 | * |
322 | * Useful combinations of the flag bits are: |
323 | * |
324 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages |
325 | * in the range which were dirty on entry to ksys_sync_file_range() are placed |
326 | * under writeout. This is a start-write-for-data-integrity operation. |
327 | * |
328 | * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which |
329 | * are not presently under writeout. This is an asynchronous flush-to-disk |
330 | * operation. Not suitable for data integrity operations. |
331 | * |
332 | * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for |
333 | * completion of writeout of all pages in the range. This will be used after an |
334 | * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait |
335 | * for that operation to complete and to return the result. |
336 | * |
337 | * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER |
338 | * (a.k.a. SYNC_FILE_RANGE_WRITE_AND_WAIT): |
339 | * a traditional sync() operation. This is a write-for-data-integrity operation |
340 | * which will ensure that all pages in the range which were dirty on entry to |
341 | * ksys_sync_file_range() are written to disk. It should be noted that disk |
342 | * caches are not flushed by this call, so there are no guarantees here that the |
343 | * data will be available on disk after a crash. |
344 | * |
345 | * |
346 | * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any |
347 | * I/O errors or ENOSPC conditions and will return those to the caller, after |
348 | * clearing the EIO and ENOSPC flags in the address_space. |
349 | * |
350 | * It should be noted that none of these operations write out the file's |
351 | * metadata. So unless the application is strictly performing overwrites of |
352 | * already-instantiated disk blocks, there are no guarantees here that the data |
353 | * will be available after a crash. |
354 | */ |
355 | int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes, |
356 | unsigned int flags) |
357 | { |
358 | int ret; |
359 | struct fd f; |
360 | |
361 | ret = -EBADF; |
362 | f = fdget(fd); |
363 | if (f.file) |
364 | ret = sync_file_range(file: f.file, offset, nbytes, flags); |
365 | |
366 | fdput(fd: f); |
367 | return ret; |
368 | } |
369 | |
370 | SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes, |
371 | unsigned int, flags) |
372 | { |
373 | return ksys_sync_file_range(fd, offset, nbytes, flags); |
374 | } |
375 | |
376 | #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_SYNC_FILE_RANGE) |
377 | COMPAT_SYSCALL_DEFINE6(sync_file_range, int, fd, compat_arg_u64_dual(offset), |
378 | compat_arg_u64_dual(nbytes), unsigned int, flags) |
379 | { |
380 | return ksys_sync_file_range(fd, compat_arg_u64_glue(offset), |
381 | compat_arg_u64_glue(nbytes), flags); |
382 | } |
383 | #endif |
384 | |
385 | /* It would be nice if people remember that not all the world's an i386 |
386 | when they introduce new system calls */ |
387 | SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags, |
388 | loff_t, offset, loff_t, nbytes) |
389 | { |
390 | return ksys_sync_file_range(fd, offset, nbytes, flags); |
391 | } |
392 | |