2 * High-level sync()-related operations
5 #include <linux/kernel.h>
6 #include <linux/file.h>
8 #include <linux/slab.h>
9 #include <linux/module.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/buffer_head.h>
18 #include <linux/backing-dev.h>
21 #define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
22 SYNC_FILE_RANGE_WAIT_AFTER)
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.
31 static int __sync_filesystem(struct super_block
*sb
, int wait
)
34 * This should be safe, as we require bdi backing to actually
35 * write out data in the first place
37 if (sb
->s_bdi
== &noop_backing_dev_info
)
40 if (sb
->s_qcop
&& sb
->s_qcop
->quota_sync
)
41 sb
->s_qcop
->quota_sync(sb
, -1, wait
);
46 writeback_inodes_sb(sb
, WB_REASON_SYNC
);
48 if (sb
->s_op
->sync_fs
)
49 sb
->s_op
->sync_fs(sb
, wait
);
50 return __sync_blockdev(sb
->s_bdev
, wait
);
54 * Write out and wait upon all dirty data associated with this
55 * superblock. Filesystem data as well as the underlying block
56 * device. Takes the superblock lock.
58 int sync_filesystem(struct super_block
*sb
)
63 * We need to be protected against the filesystem going from
64 * r/o to r/w or vice versa.
66 WARN_ON(!rwsem_is_locked(&sb
->s_umount
));
69 * No point in syncing out anything if the filesystem is read-only.
71 if (sb
->s_flags
& MS_RDONLY
)
74 ret
= __sync_filesystem(sb
, 0);
77 return __sync_filesystem(sb
, 1);
79 EXPORT_SYMBOL_GPL(sync_filesystem
);
81 static void sync_one_sb(struct super_block
*sb
, void *arg
)
83 if (!(sb
->s_flags
& MS_RDONLY
))
84 __sync_filesystem(sb
, *(int *)arg
);
87 * Sync all the data for all the filesystems (called by sys_sync() and
90 static void sync_filesystems(int wait
)
92 iterate_supers(sync_one_sb
, &wait
);
96 * sync everything. Start out by waking pdflush, because that writes back
97 * all queues in parallel.
101 wakeup_flusher_threads(0, WB_REASON_SYNC
);
104 if (unlikely(laptop_mode
))
105 laptop_sync_completion();
109 static void do_sync_work(struct work_struct
*work
)
112 * Sync twice to reduce the possibility we skipped some inodes / pages
113 * because they were temporarily locked
117 printk("Emergency Sync complete\n");
121 void emergency_sync(void)
123 struct work_struct
*work
;
125 work
= kmalloc(sizeof(*work
), GFP_ATOMIC
);
127 INIT_WORK(work
, do_sync_work
);
133 * sync a single super
135 SYSCALL_DEFINE1(syncfs
, int, fd
)
138 struct super_block
*sb
;
142 file
= fget_light(fd
, &fput_needed
);
145 sb
= file
->f_dentry
->d_sb
;
147 down_read(&sb
->s_umount
);
148 ret
= sync_filesystem(sb
);
149 up_read(&sb
->s_umount
);
151 fput_light(file
, fput_needed
);
156 * vfs_fsync_range - helper to sync a range of data & metadata to disk
157 * @file: file to sync
158 * @start: offset in bytes of the beginning of data range to sync
159 * @end: offset in bytes of the end of data range (inclusive)
160 * @datasync: perform only datasync
162 * Write back data in range @start..@end and metadata for @file to disk. If
163 * @datasync is set only metadata needed to access modified file data is
166 int vfs_fsync_range(struct file
*file
, loff_t start
, loff_t end
, int datasync
)
168 if (!file
->f_op
|| !file
->f_op
->fsync
)
170 return file
->f_op
->fsync(file
, start
, end
, datasync
);
172 EXPORT_SYMBOL(vfs_fsync_range
);
175 * vfs_fsync - perform a fsync or fdatasync on a file
176 * @file: file to sync
177 * @datasync: only perform a fdatasync operation
179 * Write back data and metadata for @file to disk. If @datasync is
180 * set only metadata needed to access modified file data is written.
182 int vfs_fsync(struct file
*file
, int datasync
)
184 return vfs_fsync_range(file
, 0, LLONG_MAX
, datasync
);
186 EXPORT_SYMBOL(vfs_fsync
);
188 static int do_fsync(unsigned int fd
, int datasync
)
195 ret
= vfs_fsync(file
, datasync
);
201 SYSCALL_DEFINE1(fsync
, unsigned int, fd
)
203 return do_fsync(fd
, 0);
206 SYSCALL_DEFINE1(fdatasync
, unsigned int, fd
)
208 return do_fsync(fd
, 1);
212 * generic_write_sync - perform syncing after a write if file / inode is sync
213 * @file: file to which the write happened
214 * @pos: offset where the write started
215 * @count: length of the write
217 * This is just a simple wrapper about our general syncing function.
219 int generic_write_sync(struct file
*file
, loff_t pos
, loff_t count
)
221 if (!(file
->f_flags
& O_DSYNC
) && !IS_SYNC(file
->f_mapping
->host
))
223 return vfs_fsync_range(file
, pos
, pos
+ count
- 1,
224 (file
->f_flags
& __O_SYNC
) ? 0 : 1);
226 EXPORT_SYMBOL(generic_write_sync
);
229 * sys_sync_file_range() permits finely controlled syncing over a segment of
230 * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
231 * zero then sys_sync_file_range() will operate from offset out to EOF.
235 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
236 * before performing the write.
238 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
239 * range which are not presently under writeback. Note that this may block for
240 * significant periods due to exhaustion of disk request structures.
242 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
243 * after performing the write.
245 * Useful combinations of the flag bits are:
247 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
248 * in the range which were dirty on entry to sys_sync_file_range() are placed
249 * under writeout. This is a start-write-for-data-integrity operation.
251 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
252 * are not presently under writeout. This is an asynchronous flush-to-disk
253 * operation. Not suitable for data integrity operations.
255 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
256 * completion of writeout of all pages in the range. This will be used after an
257 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
258 * for that operation to complete and to return the result.
260 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
261 * a traditional sync() operation. This is a write-for-data-integrity operation
262 * which will ensure that all pages in the range which were dirty on entry to
263 * sys_sync_file_range() are committed to disk.
266 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
267 * I/O errors or ENOSPC conditions and will return those to the caller, after
268 * clearing the EIO and ENOSPC flags in the address_space.
270 * It should be noted that none of these operations write out the file's
271 * metadata. So unless the application is strictly performing overwrites of
272 * already-instantiated disk blocks, there are no guarantees here that the data
273 * will be available after a crash.
275 SYSCALL_DEFINE(sync_file_range
)(int fd
, loff_t offset
, loff_t nbytes
,
280 struct address_space
*mapping
;
281 loff_t endbyte
; /* inclusive */
286 if (flags
& ~VALID_FLAGS
)
289 endbyte
= offset
+ nbytes
;
293 if ((s64
)endbyte
< 0)
295 if (endbyte
< offset
)
298 if (sizeof(pgoff_t
) == 4) {
299 if (offset
>= (0x100000000ULL
<< PAGE_CACHE_SHIFT
)) {
301 * The range starts outside a 32 bit machine's
302 * pagecache addressing capabilities. Let it "succeed"
307 if (endbyte
>= (0x100000000ULL
<< PAGE_CACHE_SHIFT
)) {
318 endbyte
--; /* inclusive */
321 file
= fget_light(fd
, &fput_needed
);
325 i_mode
= file
->f_path
.dentry
->d_inode
->i_mode
;
327 if (!S_ISREG(i_mode
) && !S_ISBLK(i_mode
) && !S_ISDIR(i_mode
) &&
331 mapping
= file
->f_mapping
;
338 if (flags
& SYNC_FILE_RANGE_WAIT_BEFORE
) {
339 ret
= filemap_fdatawait_range(mapping
, offset
, endbyte
);
344 if (flags
& SYNC_FILE_RANGE_WRITE
) {
345 ret
= filemap_fdatawrite_range(mapping
, offset
, endbyte
);
350 if (flags
& SYNC_FILE_RANGE_WAIT_AFTER
)
351 ret
= filemap_fdatawait_range(mapping
, offset
, endbyte
);
354 fput_light(file
, fput_needed
);
358 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
359 asmlinkage
long SyS_sync_file_range(long fd
, loff_t offset
, loff_t nbytes
,
362 return SYSC_sync_file_range((int) fd
, offset
, nbytes
,
363 (unsigned int) flags
);
365 SYSCALL_ALIAS(sys_sync_file_range
, SyS_sync_file_range
);
368 /* It would be nice if people remember that not all the world's an i386
369 when they introduce new system calls */
370 SYSCALL_DEFINE(sync_file_range2
)(int fd
, unsigned int flags
,
371 loff_t offset
, loff_t nbytes
)
373 return sys_sync_file_range(fd
, offset
, nbytes
, flags
);
375 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
376 asmlinkage
long SyS_sync_file_range2(long fd
, long flags
,
377 loff_t offset
, loff_t nbytes
)
379 return SYSC_sync_file_range2((int) fd
, (unsigned int) flags
,
382 SYSCALL_ALIAS(sys_sync_file_range2
, SyS_sync_file_range2
);