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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * High-level sync()-related operations
4 */
5
6#include <linux/kernel.h>
7#include <linux/file.h>
8#include <linux/fs.h>
9#include <linux/slab.h>
10#include <linux/export.h>
11#include <linux/namei.h>
12#include <linux/sched.h>
13#include <linux/writeback.h>
14#include <linux/syscalls.h>
15#include <linux/linkage.h>
16#include <linux/pagemap.h>
17#include <linux/quotaops.h>
18#include <linux/backing-dev.h>
19#include "internal.h"
20
21#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
22 SYNC_FILE_RANGE_WAIT_AFTER)
23
24/*
25 * Do the filesystem syncing work. For simple filesystems
26 * writeback_inodes_sb(sb) just dirties buffers with inodes so we have to
27 * submit IO for these buffers via __sync_blockdev(). This also speeds up the
28 * wait == 1 case since in that case write_inode() functions do
29 * sync_dirty_buffer() and thus effectively write one block at a time.
30 */
31static int __sync_filesystem(struct super_block *sb, int wait)
32{
33 if (wait)
34 sync_inodes_sb(sb);
35 else
36 writeback_inodes_sb(sb, WB_REASON_SYNC);
37
38 if (sb->s_op->sync_fs)
39 sb->s_op->sync_fs(sb, wait);
40 return __sync_blockdev(sb->s_bdev, wait);
41}
42
43/*
44 * Write out and wait upon all dirty data associated with this
45 * superblock. Filesystem data as well as the underlying block
46 * device. Takes the superblock lock.
47 */
48int sync_filesystem(struct super_block *sb)
49{
50 int ret;
51
52 /*
53 * We need to be protected against the filesystem going from
54 * r/o to r/w or vice versa.
55 */
56 WARN_ON(!rwsem_is_locked(&sb->s_umount));
57
58 /*
59 * No point in syncing out anything if the filesystem is read-only.
60 */
61 if (sb_rdonly(sb))
62 return 0;
63
64 ret = __sync_filesystem(sb, 0);
65 if (ret < 0)
66 return ret;
67 return __sync_filesystem(sb, 1);
68}
69EXPORT_SYMBOL(sync_filesystem);
70
71static void sync_inodes_one_sb(struct super_block *sb, void *arg)
72{
73 if (!sb_rdonly(sb))
74 sync_inodes_sb(sb);
75}
76
77static void sync_fs_one_sb(struct super_block *sb, void *arg)
78{
79 if (!sb_rdonly(sb) && !(sb->s_iflags & SB_I_SKIP_SYNC) &&
80 sb->s_op->sync_fs)
81 sb->s_op->sync_fs(sb, *(int *)arg);
82}
83
84static void fdatawrite_one_bdev(struct block_device *bdev, void *arg)
85{
86 filemap_fdatawrite(bdev->bd_inode->i_mapping);
87}
88
89static void fdatawait_one_bdev(struct block_device *bdev, void *arg)
90{
91 /*
92 * We keep the error status of individual mapping so that
93 * applications can catch the writeback error using fsync(2).
94 * See filemap_fdatawait_keep_errors() for details.
95 */
96 filemap_fdatawait_keep_errors(bdev->bd_inode->i_mapping);
97}
98
99/*
100 * Sync everything. We start by waking flusher threads so that most of
101 * writeback runs on all devices in parallel. Then we sync all inodes reliably
102 * which effectively also waits for all flusher threads to finish doing
103 * writeback. At this point all data is on disk so metadata should be stable
104 * and we tell filesystems to sync their metadata via ->sync_fs() calls.
105 * Finally, we writeout all block devices because some filesystems (e.g. ext2)
106 * just write metadata (such as inodes or bitmaps) to block device page cache
107 * and do not sync it on their own in ->sync_fs().
108 */
109void ksys_sync(void)
110{
111 int nowait = 0, wait = 1;
112
113 wakeup_flusher_threads(WB_REASON_SYNC);
114 iterate_supers(sync_inodes_one_sb, NULL);
115 iterate_supers(sync_fs_one_sb, &nowait);
116 iterate_supers(sync_fs_one_sb, &wait);
117 iterate_bdevs(fdatawrite_one_bdev, NULL);
118 iterate_bdevs(fdatawait_one_bdev, NULL);
119 if (unlikely(laptop_mode))
120 laptop_sync_completion();
121}
122
123SYSCALL_DEFINE0(sync)
124{
125 ksys_sync();
126 return 0;
127}
128
129static void do_sync_work(struct work_struct *work)
130{
131 int nowait = 0;
132
133 /*
134 * Sync twice to reduce the possibility we skipped some inodes / pages
135 * because they were temporarily locked
136 */
137 iterate_supers(sync_inodes_one_sb, &nowait);
138 iterate_supers(sync_fs_one_sb, &nowait);
139 iterate_bdevs(fdatawrite_one_bdev, NULL);
140 iterate_supers(sync_inodes_one_sb, &nowait);
141 iterate_supers(sync_fs_one_sb, &nowait);
142 iterate_bdevs(fdatawrite_one_bdev, NULL);
143 printk("Emergency Sync complete\n");
144 kfree(work);
145}
146
147void emergency_sync(void)
148{
149 struct work_struct *work;
150
151 work = kmalloc(sizeof(*work), GFP_ATOMIC);
152 if (work) {
153 INIT_WORK(work, do_sync_work);
154 schedule_work(work);
155 }
156}
157
158/*
159 * sync a single super
160 */
161SYSCALL_DEFINE1(syncfs, int, fd)
162{
163 struct fd f = fdget(fd);
164 struct super_block *sb;
165 int ret, ret2;
166
167 if (!f.file)
168 return -EBADF;
169 sb = f.file->f_path.dentry->d_sb;
170
171 down_read(&sb->s_umount);
172 ret = sync_filesystem(sb);
173 up_read(&sb->s_umount);
174
175 ret2 = errseq_check_and_advance(&sb->s_wb_err, &f.file->f_sb_err);
176
177 fdput(f);
178 return ret ? ret : ret2;
179}
180
181/**
182 * vfs_fsync_range - helper to sync a range of data & metadata to disk
183 * @file: file to sync
184 * @start: offset in bytes of the beginning of data range to sync
185 * @end: offset in bytes of the end of data range (inclusive)
186 * @datasync: perform only datasync
187 *
188 * Write back data in range @start..@end and metadata for @file to disk. If
189 * @datasync is set only metadata needed to access modified file data is
190 * written.
191 */
192int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync)
193{
194 struct inode *inode = file->f_mapping->host;
195
196 if (!file->f_op->fsync)
197 return -EINVAL;
198 if (!datasync && (inode->i_state & I_DIRTY_TIME))
199 mark_inode_dirty_sync(inode);
200 return file->f_op->fsync(file, start, end, datasync);
201}
202EXPORT_SYMBOL(vfs_fsync_range);
203
204/**
205 * vfs_fsync - perform a fsync or fdatasync on a file
206 * @file: file to sync
207 * @datasync: only perform a fdatasync operation
208 *
209 * Write back data and metadata for @file to disk. If @datasync is
210 * set only metadata needed to access modified file data is written.
211 */
212int vfs_fsync(struct file *file, int datasync)
213{
214 return vfs_fsync_range(file, 0, LLONG_MAX, datasync);
215}
216EXPORT_SYMBOL(vfs_fsync);
217
218static int do_fsync(unsigned int fd, int datasync)
219{
220 struct fd f = fdget(fd);
221 int ret = -EBADF;
222
223 if (f.file) {
224 ret = vfs_fsync(f.file, datasync);
225 fdput(f);
226 }
227 return ret;
228}
229
230SYSCALL_DEFINE1(fsync, unsigned int, fd)
231{
232 return do_fsync(fd, 0);
233}
234
235SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
236{
237 return do_fsync(fd, 1);
238}
239
240int sync_file_range(struct file *file, loff_t offset, loff_t nbytes,
241 unsigned int flags)
242{
243 int ret;
244 struct address_space *mapping;
245 loff_t endbyte; /* inclusive */
246 umode_t i_mode;
247
248 ret = -EINVAL;
249 if (flags & ~VALID_FLAGS)
250 goto out;
251
252 endbyte = offset + nbytes;
253
254 if ((s64)offset < 0)
255 goto out;
256 if ((s64)endbyte < 0)
257 goto out;
258 if (endbyte < offset)
259 goto out;
260
261 if (sizeof(pgoff_t) == 4) {
262 if (offset >= (0x100000000ULL << PAGE_SHIFT)) {
263 /*
264 * The range starts outside a 32 bit machine's
265 * pagecache addressing capabilities. Let it "succeed"
266 */
267 ret = 0;
268 goto out;
269 }
270 if (endbyte >= (0x100000000ULL << PAGE_SHIFT)) {
271 /*
272 * Out to EOF
273 */
274 nbytes = 0;
275 }
276 }
277
278 if (nbytes == 0)
279 endbyte = LLONG_MAX;
280 else
281 endbyte--; /* inclusive */
282
283 i_mode = file_inode(file)->i_mode;
284 ret = -ESPIPE;
285 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
286 !S_ISLNK(i_mode))
287 goto out;
288
289 mapping = file->f_mapping;
290 ret = 0;
291 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
292 ret = file_fdatawait_range(file, offset, endbyte);
293 if (ret < 0)
294 goto out;
295 }
296
297 if (flags & SYNC_FILE_RANGE_WRITE) {
298 int sync_mode = WB_SYNC_NONE;
299
300 if ((flags & SYNC_FILE_RANGE_WRITE_AND_WAIT) ==
301 SYNC_FILE_RANGE_WRITE_AND_WAIT)
302 sync_mode = WB_SYNC_ALL;
303
304 ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
305 sync_mode);
306 if (ret < 0)
307 goto out;
308 }
309
310 if (flags & SYNC_FILE_RANGE_WAIT_AFTER)
311 ret = file_fdatawait_range(file, offset, endbyte);
312
313out:
314 return ret;
315}
316
317/*
318 * ksys_sync_file_range() permits finely controlled syncing over a segment of
319 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
320 * zero then ksys_sync_file_range() will operate from offset out to EOF.
321 *
322 * The flag bits are:
323 *
324 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
325 * before performing the write.
326 *
327 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
328 * range which are not presently under writeback. Note that this may block for
329 * significant periods due to exhaustion of disk request structures.
330 *
331 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
332 * after performing the write.
333 *
334 * Useful combinations of the flag bits are:
335 *
336 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
337 * in the range which were dirty on entry to ksys_sync_file_range() are placed
338 * under writeout. This is a start-write-for-data-integrity operation.
339 *
340 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
341 * are not presently under writeout. This is an asynchronous flush-to-disk
342 * operation. Not suitable for data integrity operations.
343 *
344 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
345 * completion of writeout of all pages in the range. This will be used after an
346 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
347 * for that operation to complete and to return the result.
348 *
349 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER
350 * (a.k.a. SYNC_FILE_RANGE_WRITE_AND_WAIT):
351 * a traditional sync() operation. This is a write-for-data-integrity operation
352 * which will ensure that all pages in the range which were dirty on entry to
353 * ksys_sync_file_range() are written to disk. It should be noted that disk
354 * caches are not flushed by this call, so there are no guarantees here that the
355 * data will be available on disk after a crash.
356 *
357 *
358 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
359 * I/O errors or ENOSPC conditions and will return those to the caller, after
360 * clearing the EIO and ENOSPC flags in the address_space.
361 *
362 * It should be noted that none of these operations write out the file's
363 * metadata. So unless the application is strictly performing overwrites of
364 * already-instantiated disk blocks, there are no guarantees here that the data
365 * will be available after a crash.
366 */
367int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
368 unsigned int flags)
369{
370 int ret;
371 struct fd f;
372
373 ret = -EBADF;
374 f = fdget(fd);
375 if (f.file)
376 ret = sync_file_range(f.file, offset, nbytes, flags);
377
378 fdput(f);
379 return ret;
380}
381
382SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes,
383 unsigned int, flags)
384{
385 return ksys_sync_file_range(fd, offset, nbytes, flags);
386}
387
388/* It would be nice if people remember that not all the world's an i386
389 when they introduce new system calls */
390SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags,
391 loff_t, offset, loff_t, nbytes)
392{
393 return ksys_sync_file_range(fd, offset, nbytes, flags);
394}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * High-level sync()-related operations
4 */
5
6#include <linux/kernel.h>
7#include <linux/file.h>
8#include <linux/fs.h>
9#include <linux/slab.h>
10#include <linux/export.h>
11#include <linux/namei.h>
12#include <linux/sched.h>
13#include <linux/writeback.h>
14#include <linux/syscalls.h>
15#include <linux/linkage.h>
16#include <linux/pagemap.h>
17#include <linux/quotaops.h>
18#include <linux/backing-dev.h>
19#include "internal.h"
20
21#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
22 SYNC_FILE_RANGE_WAIT_AFTER)
23
24/*
25 * Do the filesystem syncing work. For simple filesystems
26 * writeback_inodes_sb(sb) just dirties buffers with inodes so we have to
27 * submit IO for these buffers via __sync_blockdev(). This also speeds up the
28 * wait == 1 case since in that case write_inode() functions do
29 * sync_dirty_buffer() and thus effectively write one block at a time.
30 */
31static int __sync_filesystem(struct super_block *sb, int wait)
32{
33 if (wait)
34 sync_inodes_sb(sb);
35 else
36 writeback_inodes_sb(sb, WB_REASON_SYNC);
37
38 if (sb->s_op->sync_fs)
39 sb->s_op->sync_fs(sb, wait);
40 return __sync_blockdev(sb->s_bdev, wait);
41}
42
43/*
44 * Write out and wait upon all dirty data associated with this
45 * superblock. Filesystem data as well as the underlying block
46 * device. Takes the superblock lock.
47 */
48int sync_filesystem(struct super_block *sb)
49{
50 int ret;
51
52 /*
53 * We need to be protected against the filesystem going from
54 * r/o to r/w or vice versa.
55 */
56 WARN_ON(!rwsem_is_locked(&sb->s_umount));
57
58 /*
59 * No point in syncing out anything if the filesystem is read-only.
60 */
61 if (sb_rdonly(sb))
62 return 0;
63
64 ret = __sync_filesystem(sb, 0);
65 if (ret < 0)
66 return ret;
67 return __sync_filesystem(sb, 1);
68}
69EXPORT_SYMBOL(sync_filesystem);
70
71static void sync_inodes_one_sb(struct super_block *sb, void *arg)
72{
73 if (!sb_rdonly(sb))
74 sync_inodes_sb(sb);
75}
76
77static void sync_fs_one_sb(struct super_block *sb, void *arg)
78{
79 if (!sb_rdonly(sb) && sb->s_op->sync_fs)
80 sb->s_op->sync_fs(sb, *(int *)arg);
81}
82
83static void fdatawrite_one_bdev(struct block_device *bdev, void *arg)
84{
85 filemap_fdatawrite(bdev->bd_inode->i_mapping);
86}
87
88static void fdatawait_one_bdev(struct block_device *bdev, void *arg)
89{
90 /*
91 * We keep the error status of individual mapping so that
92 * applications can catch the writeback error using fsync(2).
93 * See filemap_fdatawait_keep_errors() for details.
94 */
95 filemap_fdatawait_keep_errors(bdev->bd_inode->i_mapping);
96}
97
98/*
99 * Sync everything. We start by waking flusher threads so that most of
100 * writeback runs on all devices in parallel. Then we sync all inodes reliably
101 * which effectively also waits for all flusher threads to finish doing
102 * writeback. At this point all data is on disk so metadata should be stable
103 * and we tell filesystems to sync their metadata via ->sync_fs() calls.
104 * Finally, we writeout all block devices because some filesystems (e.g. ext2)
105 * just write metadata (such as inodes or bitmaps) to block device page cache
106 * and do not sync it on their own in ->sync_fs().
107 */
108void ksys_sync(void)
109{
110 int nowait = 0, wait = 1;
111
112 wakeup_flusher_threads(WB_REASON_SYNC);
113 iterate_supers(sync_inodes_one_sb, NULL);
114 iterate_supers(sync_fs_one_sb, &nowait);
115 iterate_supers(sync_fs_one_sb, &wait);
116 iterate_bdevs(fdatawrite_one_bdev, NULL);
117 iterate_bdevs(fdatawait_one_bdev, NULL);
118 if (unlikely(laptop_mode))
119 laptop_sync_completion();
120}
121
122SYSCALL_DEFINE0(sync)
123{
124 ksys_sync();
125 return 0;
126}
127
128static void do_sync_work(struct work_struct *work)
129{
130 int nowait = 0;
131
132 /*
133 * Sync twice to reduce the possibility we skipped some inodes / pages
134 * because they were temporarily locked
135 */
136 iterate_supers(sync_inodes_one_sb, &nowait);
137 iterate_supers(sync_fs_one_sb, &nowait);
138 iterate_bdevs(fdatawrite_one_bdev, NULL);
139 iterate_supers(sync_inodes_one_sb, &nowait);
140 iterate_supers(sync_fs_one_sb, &nowait);
141 iterate_bdevs(fdatawrite_one_bdev, NULL);
142 printk("Emergency Sync complete\n");
143 kfree(work);
144}
145
146void emergency_sync(void)
147{
148 struct work_struct *work;
149
150 work = kmalloc(sizeof(*work), GFP_ATOMIC);
151 if (work) {
152 INIT_WORK(work, do_sync_work);
153 schedule_work(work);
154 }
155}
156
157/*
158 * sync a single super
159 */
160SYSCALL_DEFINE1(syncfs, int, fd)
161{
162 struct fd f = fdget(fd);
163 struct super_block *sb;
164 int ret;
165
166 if (!f.file)
167 return -EBADF;
168 sb = f.file->f_path.dentry->d_sb;
169
170 down_read(&sb->s_umount);
171 ret = sync_filesystem(sb);
172 up_read(&sb->s_umount);
173
174 fdput(f);
175 return ret;
176}
177
178/**
179 * vfs_fsync_range - helper to sync a range of data & metadata to disk
180 * @file: file to sync
181 * @start: offset in bytes of the beginning of data range to sync
182 * @end: offset in bytes of the end of data range (inclusive)
183 * @datasync: perform only datasync
184 *
185 * Write back data in range @start..@end and metadata for @file to disk. If
186 * @datasync is set only metadata needed to access modified file data is
187 * written.
188 */
189int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync)
190{
191 struct inode *inode = file->f_mapping->host;
192
193 if (!file->f_op->fsync)
194 return -EINVAL;
195 if (!datasync && (inode->i_state & I_DIRTY_TIME))
196 mark_inode_dirty_sync(inode);
197 return file->f_op->fsync(file, start, end, datasync);
198}
199EXPORT_SYMBOL(vfs_fsync_range);
200
201/**
202 * vfs_fsync - perform a fsync or fdatasync on a file
203 * @file: file to sync
204 * @datasync: only perform a fdatasync operation
205 *
206 * Write back data and metadata for @file to disk. If @datasync is
207 * set only metadata needed to access modified file data is written.
208 */
209int vfs_fsync(struct file *file, int datasync)
210{
211 return vfs_fsync_range(file, 0, LLONG_MAX, datasync);
212}
213EXPORT_SYMBOL(vfs_fsync);
214
215static int do_fsync(unsigned int fd, int datasync)
216{
217 struct fd f = fdget(fd);
218 int ret = -EBADF;
219
220 if (f.file) {
221 ret = vfs_fsync(f.file, datasync);
222 fdput(f);
223 }
224 return ret;
225}
226
227SYSCALL_DEFINE1(fsync, unsigned int, fd)
228{
229 return do_fsync(fd, 0);
230}
231
232SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
233{
234 return do_fsync(fd, 1);
235}
236
237int sync_file_range(struct file *file, loff_t offset, loff_t nbytes,
238 unsigned int flags)
239{
240 int ret;
241 struct address_space *mapping;
242 loff_t endbyte; /* inclusive */
243 umode_t i_mode;
244
245 ret = -EINVAL;
246 if (flags & ~VALID_FLAGS)
247 goto out;
248
249 endbyte = offset + nbytes;
250
251 if ((s64)offset < 0)
252 goto out;
253 if ((s64)endbyte < 0)
254 goto out;
255 if (endbyte < offset)
256 goto out;
257
258 if (sizeof(pgoff_t) == 4) {
259 if (offset >= (0x100000000ULL << PAGE_SHIFT)) {
260 /*
261 * The range starts outside a 32 bit machine's
262 * pagecache addressing capabilities. Let it "succeed"
263 */
264 ret = 0;
265 goto out;
266 }
267 if (endbyte >= (0x100000000ULL << PAGE_SHIFT)) {
268 /*
269 * Out to EOF
270 */
271 nbytes = 0;
272 }
273 }
274
275 if (nbytes == 0)
276 endbyte = LLONG_MAX;
277 else
278 endbyte--; /* inclusive */
279
280 i_mode = file_inode(file)->i_mode;
281 ret = -ESPIPE;
282 if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
283 !S_ISLNK(i_mode))
284 goto out;
285
286 mapping = file->f_mapping;
287 ret = 0;
288 if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
289 ret = file_fdatawait_range(file, offset, endbyte);
290 if (ret < 0)
291 goto out;
292 }
293
294 if (flags & SYNC_FILE_RANGE_WRITE) {
295 int sync_mode = WB_SYNC_NONE;
296
297 if ((flags & SYNC_FILE_RANGE_WRITE_AND_WAIT) ==
298 SYNC_FILE_RANGE_WRITE_AND_WAIT)
299 sync_mode = WB_SYNC_ALL;
300
301 ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
302 sync_mode);
303 if (ret < 0)
304 goto out;
305 }
306
307 if (flags & SYNC_FILE_RANGE_WAIT_AFTER)
308 ret = file_fdatawait_range(file, offset, endbyte);
309
310out:
311 return ret;
312}
313
314/*
315 * ksys_sync_file_range() permits finely controlled syncing over a segment of
316 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
317 * zero then ksys_sync_file_range() will operate from offset out to EOF.
318 *
319 * The flag bits are:
320 *
321 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
322 * before performing the write.
323 *
324 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
325 * range which are not presently under writeback. Note that this may block for
326 * significant periods due to exhaustion of disk request structures.
327 *
328 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
329 * after performing the write.
330 *
331 * Useful combinations of the flag bits are:
332 *
333 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
334 * in the range which were dirty on entry to ksys_sync_file_range() are placed
335 * under writeout. This is a start-write-for-data-integrity operation.
336 *
337 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
338 * are not presently under writeout. This is an asynchronous flush-to-disk
339 * operation. Not suitable for data integrity operations.
340 *
341 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
342 * completion of writeout of all pages in the range. This will be used after an
343 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
344 * for that operation to complete and to return the result.
345 *
346 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER
347 * (a.k.a. SYNC_FILE_RANGE_WRITE_AND_WAIT):
348 * a traditional sync() operation. This is a write-for-data-integrity operation
349 * which will ensure that all pages in the range which were dirty on entry to
350 * ksys_sync_file_range() are written to disk. It should be noted that disk
351 * caches are not flushed by this call, so there are no guarantees here that the
352 * data will be available on disk after a crash.
353 *
354 *
355 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
356 * I/O errors or ENOSPC conditions and will return those to the caller, after
357 * clearing the EIO and ENOSPC flags in the address_space.
358 *
359 * It should be noted that none of these operations write out the file's
360 * metadata. So unless the application is strictly performing overwrites of
361 * already-instantiated disk blocks, there are no guarantees here that the data
362 * will be available after a crash.
363 */
364int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
365 unsigned int flags)
366{
367 int ret;
368 struct fd f;
369
370 ret = -EBADF;
371 f = fdget(fd);
372 if (f.file)
373 ret = sync_file_range(f.file, offset, nbytes, flags);
374
375 fdput(f);
376 return ret;
377}
378
379SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes,
380 unsigned int, flags)
381{
382 return ksys_sync_file_range(fd, offset, nbytes, flags);
383}
384
385/* It would be nice if people remember that not all the world's an i386
386 when they introduce new system calls */
387SYSCALL_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}