2 * High-level sync()-related operations
5 #include <linux/kernel.h>
6 #include <linux/file.h>
8 #include <linux/module.h>
9 #include <linux/sched.h>
10 #include <linux/writeback.h>
11 #include <linux/syscalls.h>
12 #include <linux/linkage.h>
13 #include <linux/pagemap.h>
14 #include <linux/quotaops.h>
15 #include <linux/buffer_head.h>
18 #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
19 SYNC_FILE_RANGE_WAIT_AFTER)
22 * Do the filesystem syncing work. For simple filesystems sync_inodes_sb(sb, 0)
23 * just dirties buffers with inodes so we have to submit IO for these buffers
24 * via __sync_blockdev(). This also speeds up the wait == 1 case since in that
25 * case write_inode() functions do sync_dirty_buffer() and thus effectively
26 * write one block at a time.
28 static int __sync_filesystem(struct super_block
*sb
, int wait
)
30 /* Avoid doing twice syncing and cache pruning for quota sync */
32 writeout_quota_sb(sb
, -1);
34 sync_quota_sb(sb
, -1);
35 sync_inodes_sb(sb
, wait
);
37 if (sb
->s_dirt
&& sb
->s_op
->write_super
)
38 sb
->s_op
->write_super(sb
);
40 if (sb
->s_op
->sync_fs
)
41 sb
->s_op
->sync_fs(sb
, wait
);
42 return __sync_blockdev(sb
->s_bdev
, wait
);
46 * Write out and wait upon all dirty data associated with this
47 * superblock. Filesystem data as well as the underlying block
48 * device. Takes the superblock lock.
50 int sync_filesystem(struct super_block
*sb
)
54 ret
= __sync_filesystem(sb
, 0);
57 return __sync_filesystem(sb
, 1);
59 EXPORT_SYMBOL_GPL(sync_filesystem
);
62 * Sync all the data for all the filesystems (called by sys_sync() and
65 * This operation is careful to avoid the livelock which could easily happen
66 * if two or more filesystems are being continuously dirtied. s_need_sync
67 * is used only here. We set it against all filesystems and then clear it as
68 * we sync them. So redirtied filesystems are skipped.
70 * But if process A is currently running sync_filesystems and then process B
71 * calls sync_filesystems as well, process B will set all the s_need_sync
72 * flags again, which will cause process A to resync everything. Fix that with
75 static void sync_filesystems(int wait
)
77 struct super_block
*sb
;
78 static DEFINE_MUTEX(mutex
);
80 mutex_lock(&mutex
); /* Could be down_interruptible */
82 list_for_each_entry(sb
, &super_blocks
, s_list
) {
83 if (sb
->s_flags
& MS_RDONLY
)
89 list_for_each_entry(sb
, &super_blocks
, s_list
) {
93 if (sb
->s_flags
& MS_RDONLY
)
94 continue; /* hm. Was remounted r/o meanwhile */
96 spin_unlock(&sb_lock
);
97 down_read(&sb
->s_umount
);
99 __sync_filesystem(sb
, wait
);
100 up_read(&sb
->s_umount
);
101 /* restart only when sb is no longer on the list */
103 if (__put_super_and_need_restart(sb
))
106 spin_unlock(&sb_lock
);
107 mutex_unlock(&mutex
);
110 SYSCALL_DEFINE0(sync
)
114 if (unlikely(laptop_mode
))
115 laptop_sync_completion();
119 static void do_sync_work(struct work_struct
*work
)
122 * Sync twice to reduce the possibility we skipped some inodes / pages
123 * because they were temporarily locked
127 printk("Emergency Sync complete\n");
131 void emergency_sync(void)
133 struct work_struct
*work
;
135 work
= kmalloc(sizeof(*work
), GFP_ATOMIC
);
137 INIT_WORK(work
, do_sync_work
);
143 * Generic function to fsync a file.
145 * filp may be NULL if called via the msync of a vma.
147 int file_fsync(struct file
*filp
, struct dentry
*dentry
, int datasync
)
149 struct inode
* inode
= dentry
->d_inode
;
150 struct super_block
* sb
;
153 /* sync the inode to buffers */
154 ret
= write_inode_now(inode
, 0);
156 /* sync the superblock to buffers */
159 if (sb
->s_dirt
&& sb
->s_op
->write_super
)
160 sb
->s_op
->write_super(sb
);
163 /* .. finally sync the buffers to disk */
164 err
= sync_blockdev(sb
->s_bdev
);
171 * vfs_fsync - perform a fsync or fdatasync on a file
172 * @file: file to sync
173 * @dentry: dentry of @file
174 * @data: only perform a fdatasync operation
176 * Write back data and metadata for @file to disk. If @datasync is
177 * set only metadata needed to access modified file data is written.
179 * In case this function is called from nfsd @file may be %NULL and
180 * only @dentry is set. This can only happen when the filesystem
181 * implements the export_operations API.
183 int vfs_fsync(struct file
*file
, struct dentry
*dentry
, int datasync
)
185 const struct file_operations
*fop
;
186 struct address_space
*mapping
;
190 * Get mapping and operations from the file in case we have
191 * as file, or get the default values for them in case we
192 * don't have a struct file available. Damn nfsd..
195 mapping
= file
->f_mapping
;
198 mapping
= dentry
->d_inode
->i_mapping
;
199 fop
= dentry
->d_inode
->i_fop
;
202 if (!fop
|| !fop
->fsync
) {
207 ret
= filemap_fdatawrite(mapping
);
210 * We need to protect against concurrent writers, which could cause
211 * livelocks in fsync_buffers_list().
213 mutex_lock(&mapping
->host
->i_mutex
);
214 err
= fop
->fsync(file
, dentry
, datasync
);
217 mutex_unlock(&mapping
->host
->i_mutex
);
218 err
= filemap_fdatawait(mapping
);
224 EXPORT_SYMBOL(vfs_fsync
);
226 static int do_fsync(unsigned int fd
, int datasync
)
233 ret
= vfs_fsync(file
, file
->f_path
.dentry
, datasync
);
239 SYSCALL_DEFINE1(fsync
, unsigned int, fd
)
241 return do_fsync(fd
, 0);
244 SYSCALL_DEFINE1(fdatasync
, unsigned int, fd
)
246 return do_fsync(fd
, 1);
250 * sys_sync_file_range() permits finely controlled syncing over a segment of
251 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
252 * zero then sys_sync_file_range() will operate from offset out to EOF.
256 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
257 * before performing the write.
259 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
260 * range which are not presently under writeback. Note that this may block for
261 * significant periods due to exhaustion of disk request structures.
263 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
264 * after performing the write.
266 * Useful combinations of the flag bits are:
268 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
269 * in the range which were dirty on entry to sys_sync_file_range() are placed
270 * under writeout. This is a start-write-for-data-integrity operation.
272 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
273 * are not presently under writeout. This is an asynchronous flush-to-disk
274 * operation. Not suitable for data integrity operations.
276 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
277 * completion of writeout of all pages in the range. This will be used after an
278 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
279 * for that operation to complete and to return the result.
281 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
282 * a traditional sync() operation. This is a write-for-data-integrity operation
283 * which will ensure that all pages in the range which were dirty on entry to
284 * sys_sync_file_range() are committed to disk.
287 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
288 * I/O errors or ENOSPC conditions and will return those to the caller, after
289 * clearing the EIO and ENOSPC flags in the address_space.
291 * It should be noted that none of these operations write out the file's
292 * metadata. So unless the application is strictly performing overwrites of
293 * already-instantiated disk blocks, there are no guarantees here that the data
294 * will be available after a crash.
296 SYSCALL_DEFINE(sync_file_range
)(int fd
, loff_t offset
, loff_t nbytes
,
301 loff_t endbyte
; /* inclusive */
306 if (flags
& ~VALID_FLAGS
)
309 endbyte
= offset
+ nbytes
;
313 if ((s64
)endbyte
< 0)
315 if (endbyte
< offset
)
318 if (sizeof(pgoff_t
) == 4) {
319 if (offset
>= (0x100000000ULL
<< PAGE_CACHE_SHIFT
)) {
321 * The range starts outside a 32 bit machine's
322 * pagecache addressing capabilities. Let it "succeed"
327 if (endbyte
>= (0x100000000ULL
<< PAGE_CACHE_SHIFT
)) {
338 endbyte
--; /* inclusive */
341 file
= fget_light(fd
, &fput_needed
);
345 i_mode
= file
->f_path
.dentry
->d_inode
->i_mode
;
347 if (!S_ISREG(i_mode
) && !S_ISBLK(i_mode
) && !S_ISDIR(i_mode
) &&
351 ret
= do_sync_mapping_range(file
->f_mapping
, offset
, endbyte
, flags
);
353 fput_light(file
, fput_needed
);
357 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
358 asmlinkage
long SyS_sync_file_range(long fd
, loff_t offset
, loff_t nbytes
,
361 return SYSC_sync_file_range((int) fd
, offset
, nbytes
,
362 (unsigned int) flags
);
364 SYSCALL_ALIAS(sys_sync_file_range
, SyS_sync_file_range
);
367 /* It would be nice if people remember that not all the world's an i386
368 when they introduce new system calls */
369 SYSCALL_DEFINE(sync_file_range2
)(int fd
, unsigned int flags
,
370 loff_t offset
, loff_t nbytes
)
372 return sys_sync_file_range(fd
, offset
, nbytes
, flags
);
374 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
375 asmlinkage
long SyS_sync_file_range2(long fd
, long flags
,
376 loff_t offset
, loff_t nbytes
)
378 return SYSC_sync_file_range2((int) fd
, (unsigned int) flags
,
381 SYSCALL_ALIAS(sys_sync_file_range2
, SyS_sync_file_range2
);
385 * `endbyte' is inclusive
387 int do_sync_mapping_range(struct address_space
*mapping
, loff_t offset
,
388 loff_t endbyte
, unsigned int flags
)
398 if (flags
& SYNC_FILE_RANGE_WAIT_BEFORE
) {
399 ret
= wait_on_page_writeback_range(mapping
,
400 offset
>> PAGE_CACHE_SHIFT
,
401 endbyte
>> PAGE_CACHE_SHIFT
);
406 if (flags
& SYNC_FILE_RANGE_WRITE
) {
407 ret
= __filemap_fdatawrite_range(mapping
, offset
, endbyte
,
413 if (flags
& SYNC_FILE_RANGE_WAIT_AFTER
) {
414 ret
= wait_on_page_writeback_range(mapping
,
415 offset
>> PAGE_CACHE_SHIFT
,
416 endbyte
>> PAGE_CACHE_SHIFT
);
421 EXPORT_SYMBOL_GPL(do_sync_mapping_range
);