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f79e2abb
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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>
5a0e3ad6 8#include <linux/slab.h>
630d9c47 9#include <linux/export.h>
b7ed78f5 10#include <linux/namei.h>
914e2637 11#include <linux/sched.h>
f79e2abb
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12#include <linux/writeback.h>
13#include <linux/syscalls.h>
14#include <linux/linkage.h>
15#include <linux/pagemap.h>
cf9a2ae8 16#include <linux/quotaops.h>
5129a469 17#include <linux/backing-dev.h>
5a3e5cb8 18#include "internal.h"
f79e2abb
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19
20#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
21 SYNC_FILE_RANGE_WAIT_AFTER)
22
c15c54f5 23/*
d8a8559c
JA
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.
c15c54f5 29 */
60b0680f 30static int __sync_filesystem(struct super_block *sb, int wait)
c15c54f5 31{
5fb324ad 32 if (wait)
d8a8559c 33 sync_inodes_sb(sb);
5fb324ad 34 else
0e175a18 35 writeback_inodes_sb(sb, WB_REASON_SYNC);
5fb324ad 36
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JK
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 */
60b0680f 47int sync_filesystem(struct super_block *sb)
c15c54f5
JK
48{
49 int ret;
50
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CH
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
60b0680f 63 ret = __sync_filesystem(sb, 0);
c15c54f5
JK
64 if (ret < 0)
65 return ret;
60b0680f 66 return __sync_filesystem(sb, 1);
c15c54f5 67}
60b0680f 68EXPORT_SYMBOL_GPL(sync_filesystem);
c15c54f5 69
b3de6531 70static void sync_inodes_one_sb(struct super_block *sb, void *arg)
01a05b33 71{
95f28604 72 if (!(sb->s_flags & MS_RDONLY))
b3de6531 73 sync_inodes_sb(sb);
01a05b33 74}
b3de6531 75
b3de6531
JK
76static 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
d0e91b13 82static void fdatawrite_one_bdev(struct block_device *bdev, void *arg)
b3de6531 83{
d0e91b13 84 filemap_fdatawrite(bdev->bd_inode->i_mapping);
a8c7176b
JK
85}
86
d0e91b13 87static void fdatawait_one_bdev(struct block_device *bdev, void *arg)
a8c7176b 88{
d0e91b13 89 filemap_fdatawait(bdev->bd_inode->i_mapping);
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90}
91
3beab0b4 92/*
4ea425b6
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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().
3beab0b4 101 */
5cee5815 102SYSCALL_DEFINE0(sync)
cf9a2ae8 103{
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104 int nowait = 0, wait = 1;
105
0e175a18 106 wakeup_flusher_threads(0, WB_REASON_SYNC);
b3de6531 107 iterate_supers(sync_inodes_one_sb, NULL);
4ea425b6 108 iterate_supers(sync_fs_one_sb, &nowait);
b3de6531 109 iterate_supers(sync_fs_one_sb, &wait);
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110 iterate_bdevs(fdatawrite_one_bdev, NULL);
111 iterate_bdevs(fdatawait_one_bdev, NULL);
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DH
112 if (unlikely(laptop_mode))
113 laptop_sync_completion();
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DH
114 return 0;
115}
116
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117static void do_sync_work(struct work_struct *work)
118{
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119 int nowait = 0;
120
5cee5815
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121 /*
122 * Sync twice to reduce the possibility we skipped some inodes / pages
123 * because they were temporarily locked
124 */
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125 iterate_supers(sync_inodes_one_sb, &nowait);
126 iterate_supers(sync_fs_one_sb, &nowait);
d0e91b13 127 iterate_bdevs(fdatawrite_one_bdev, NULL);
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128 iterate_supers(sync_inodes_one_sb, &nowait);
129 iterate_supers(sync_fs_one_sb, &nowait);
d0e91b13 130 iterate_bdevs(fdatawrite_one_bdev, NULL);
5cee5815 131 printk("Emergency Sync complete\n");
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132 kfree(work);
133}
134
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DH
135void emergency_sync(void)
136{
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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 }
cf9a2ae8
DH
144}
145
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SW
146/*
147 * sync a single super
148 */
149SYSCALL_DEFINE1(syncfs, int, fd)
150{
2903ff01 151 struct fd f = fdget(fd);
b7ed78f5
SW
152 struct super_block *sb;
153 int ret;
b7ed78f5 154
2903ff01 155 if (!f.file)
b7ed78f5 156 return -EBADF;
2903ff01 157 sb = f.file->f_dentry->d_sb;
b7ed78f5
SW
158
159 down_read(&sb->s_umount);
160 ret = sync_filesystem(sb);
161 up_read(&sb->s_umount);
162
2903ff01 163 fdput(f);
b7ed78f5
SW
164 return ret;
165}
166
4c728ef5 167/**
148f948b 168 * vfs_fsync_range - helper to sync a range of data & metadata to disk
4c728ef5 169 * @file: file to sync
148f948b
JK
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
4c728ef5 173 *
148f948b
JK
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.
4c728ef5 177 */
8018ab05 178int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync)
cf9a2ae8 179{
02c24a82
JB
180 if (!file->f_op || !file->f_op->fsync)
181 return -EINVAL;
182 return file->f_op->fsync(file, start, end, datasync);
cf9a2ae8 183}
148f948b
JK
184EXPORT_SYMBOL(vfs_fsync_range);
185
186/**
187 * vfs_fsync - perform a fsync or fdatasync on a file
188 * @file: file to sync
148f948b
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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.
148f948b 193 */
8018ab05 194int vfs_fsync(struct file *file, int datasync)
148f948b 195{
8018ab05 196 return vfs_fsync_range(file, 0, LLONG_MAX, datasync);
148f948b 197}
4c728ef5 198EXPORT_SYMBOL(vfs_fsync);
cf9a2ae8 199
4c728ef5 200static int do_fsync(unsigned int fd, int datasync)
cf9a2ae8 201{
2903ff01 202 struct fd f = fdget(fd);
cf9a2ae8
DH
203 int ret = -EBADF;
204
2903ff01
AV
205 if (f.file) {
206 ret = vfs_fsync(f.file, datasync);
207 fdput(f);
cf9a2ae8
DH
208 }
209 return ret;
210}
211
a5f8fa9e 212SYSCALL_DEFINE1(fsync, unsigned int, fd)
cf9a2ae8 213{
4c728ef5 214 return do_fsync(fd, 0);
cf9a2ae8
DH
215}
216
a5f8fa9e 217SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
cf9a2ae8 218{
4c728ef5 219 return do_fsync(fd, 1);
cf9a2ae8
DH
220}
221
148f948b
JK
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 */
230int generic_write_sync(struct file *file, loff_t pos, loff_t count)
231{
6b2f3d1f 232 if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
148f948b 233 return 0;
8018ab05 234 return vfs_fsync_range(file, pos, pos + count - 1,
6b2f3d1f 235 (file->f_flags & __O_SYNC) ? 0 : 1);
148f948b
JK
236}
237EXPORT_SYMBOL(generic_write_sync);
238
f79e2abb
AM
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
cce77081
PM
250 * range which are not presently under writeback. Note that this may block for
251 * significant periods due to exhaustion of disk request structures.
f79e2abb
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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 */
4a0fd5bf
AV
286SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes,
287 unsigned int, flags)
f79e2abb
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288{
289 int ret;
2903ff01 290 struct fd f;
7a0ad10c 291 struct address_space *mapping;
f79e2abb 292 loff_t endbyte; /* inclusive */
f79e2abb
AM
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)
111ebb6e 326 endbyte = LLONG_MAX;
f79e2abb
AM
327 else
328 endbyte--; /* inclusive */
329
330 ret = -EBADF;
2903ff01
AV
331 f = fdget(fd);
332 if (!f.file)
f79e2abb
AM
333 goto out;
334
496ad9aa 335 i_mode = file_inode(f.file)->i_mode;
f79e2abb
AM
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
2903ff01 341 mapping = f.file->f_mapping;
7a0ad10c
CH
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
f79e2abb 363out_put:
2903ff01 364 fdput(f);
f79e2abb
AM
365out:
366 return ret;
367}
368
edd5cd4a
DW
369/* It would be nice if people remember that not all the world's an i386
370 when they introduce new system calls */
4a0fd5bf
AV
371SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags,
372 loff_t, offset, loff_t, nbytes)
edd5cd4a
DW
373{
374 return sys_sync_file_range(fd, offset, nbytes, flags);
375}