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v3.1
 
  1/*
  2 * High-level sync()-related operations
  3 */
  4
  5#include <linux/kernel.h>
  6#include <linux/file.h>
  7#include <linux/fs.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>
 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	/*
 34	 * This should be safe, as we require bdi backing to actually
 35	 * write out data in the first place
 36	 */
 37	if (sb->s_bdi == &noop_backing_dev_info)
 38		return 0;
 39
 40	if (sb->s_qcop && sb->s_qcop->quota_sync)
 41		sb->s_qcop->quota_sync(sb, -1, wait);
 42
 43	if (wait)
 44		sync_inodes_sb(sb);
 45	else
 46		writeback_inodes_sb(sb);
 47
 48	if (sb->s_op->sync_fs)
 49		sb->s_op->sync_fs(sb, wait);
 50	return __sync_blockdev(sb->s_bdev, wait);
 51}
 52
 53/*
 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.
 57 */
 58int sync_filesystem(struct super_block *sb)
 59{
 60	int ret;
 61
 62	/*
 63	 * We need to be protected against the filesystem going from
 64	 * r/o to r/w or vice versa.
 65	 */
 66	WARN_ON(!rwsem_is_locked(&sb->s_umount));
 67
 68	/*
 69	 * No point in syncing out anything if the filesystem is read-only.
 70	 */
 71	if (sb->s_flags & MS_RDONLY)
 72		return 0;
 73
 74	ret = __sync_filesystem(sb, 0);
 75	if (ret < 0)
 76		return ret;
 77	return __sync_filesystem(sb, 1);
 78}
 79EXPORT_SYMBOL_GPL(sync_filesystem);
 80
 81static void sync_one_sb(struct super_block *sb, void *arg)
 82{
 83	if (!(sb->s_flags & MS_RDONLY))
 84		__sync_filesystem(sb, *(int *)arg);
 85}
 86/*
 87 * Sync all the data for all the filesystems (called by sys_sync() and
 88 * emergency sync)
 89 */
 90static void sync_filesystems(int wait)
 91{
 92	iterate_supers(sync_one_sb, &wait);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 93}
 94
 95/*
 96 * sync everything.  Start out by waking pdflush, because that writes back
 97 * all queues in parallel.
 
 
 
 
 
 
 98 */
 99SYSCALL_DEFINE0(sync)
100{
101	wakeup_flusher_threads(0);
102	sync_filesystems(0);
103	sync_filesystems(1);
 
 
 
 
 
104	if (unlikely(laptop_mode))
105		laptop_sync_completion();
 
 
 
 
 
106	return 0;
107}
108
109static void do_sync_work(struct work_struct *work)
110{
 
 
111	/*
112	 * Sync twice to reduce the possibility we skipped some inodes / pages
113	 * because they were temporarily locked
114	 */
115	sync_filesystems(0);
116	sync_filesystems(0);
 
 
 
 
117	printk("Emergency Sync complete\n");
118	kfree(work);
119}
120
121void emergency_sync(void)
122{
123	struct work_struct *work;
124
125	work = kmalloc(sizeof(*work), GFP_ATOMIC);
126	if (work) {
127		INIT_WORK(work, do_sync_work);
128		schedule_work(work);
129	}
130}
131
132/*
133 * sync a single super
134 */
135SYSCALL_DEFINE1(syncfs, int, fd)
136{
137	struct file *file;
138	struct super_block *sb;
139	int ret;
140	int fput_needed;
141
142	file = fget_light(fd, &fput_needed);
143	if (!file)
144		return -EBADF;
145	sb = file->f_dentry->d_sb;
146
147	down_read(&sb->s_umount);
148	ret = sync_filesystem(sb);
149	up_read(&sb->s_umount);
150
151	fput_light(file, fput_needed);
152	return ret;
153}
154
155/**
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
161 *
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
164 * written.
165 */
166int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync)
167{
168	if (!file->f_op || !file->f_op->fsync)
 
 
169		return -EINVAL;
 
 
170	return file->f_op->fsync(file, start, end, datasync);
171}
172EXPORT_SYMBOL(vfs_fsync_range);
173
174/**
175 * vfs_fsync - perform a fsync or fdatasync on a file
176 * @file:		file to sync
177 * @datasync:		only perform a fdatasync operation
178 *
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.
181 */
182int vfs_fsync(struct file *file, int datasync)
183{
184	return vfs_fsync_range(file, 0, LLONG_MAX, datasync);
185}
186EXPORT_SYMBOL(vfs_fsync);
187
188static int do_fsync(unsigned int fd, int datasync)
189{
190	struct file *file;
191	int ret = -EBADF;
192
193	file = fget(fd);
194	if (file) {
195		ret = vfs_fsync(file, datasync);
196		fput(file);
197	}
198	return ret;
199}
200
201SYSCALL_DEFINE1(fsync, unsigned int, fd)
202{
203	return do_fsync(fd, 0);
204}
205
206SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
207{
208	return do_fsync(fd, 1);
209}
210
211/**
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
216 *
217 * This is just a simple wrapper about our general syncing function.
218 */
219int generic_write_sync(struct file *file, loff_t pos, loff_t count)
220{
221	if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
222		return 0;
223	return vfs_fsync_range(file, pos, pos + count - 1,
224			       (file->f_flags & __O_SYNC) ? 0 : 1);
225}
226EXPORT_SYMBOL(generic_write_sync);
227
228/*
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.
232 *
233 * The flag bits are:
234 *
235 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
236 * before performing the write.
237 *
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.
241 *
242 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
243 * after performing the write.
244 *
245 * Useful combinations of the flag bits are:
246 *
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.
250 *
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.
254 *
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.
259 *
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.
264 *
265 *
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.
269 *
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.
274 */
275SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes,
276				unsigned int flags)
277{
278	int ret;
279	struct file *file;
280	struct address_space *mapping;
281	loff_t endbyte;			/* inclusive */
282	int fput_needed;
283	umode_t i_mode;
284
285	ret = -EINVAL;
286	if (flags & ~VALID_FLAGS)
287		goto out;
288
289	endbyte = offset + nbytes;
290
291	if ((s64)offset < 0)
292		goto out;
293	if ((s64)endbyte < 0)
294		goto out;
295	if (endbyte < offset)
296		goto out;
297
298	if (sizeof(pgoff_t) == 4) {
299		if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
300			/*
301			 * The range starts outside a 32 bit machine's
302			 * pagecache addressing capabilities.  Let it "succeed"
303			 */
304			ret = 0;
305			goto out;
306		}
307		if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
308			/*
309			 * Out to EOF
310			 */
311			nbytes = 0;
312		}
313	}
314
315	if (nbytes == 0)
316		endbyte = LLONG_MAX;
317	else
318		endbyte--;		/* inclusive */
319
320	ret = -EBADF;
321	file = fget_light(fd, &fput_needed);
322	if (!file)
323		goto out;
324
325	i_mode = file->f_path.dentry->d_inode->i_mode;
326	ret = -ESPIPE;
327	if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
328			!S_ISLNK(i_mode))
329		goto out_put;
330
331	mapping = file->f_mapping;
332	if (!mapping) {
333		ret = -EINVAL;
334		goto out_put;
335	}
336
337	ret = 0;
338	if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
339		ret = filemap_fdatawait_range(mapping, offset, endbyte);
340		if (ret < 0)
341			goto out_put;
342	}
343
344	if (flags & SYNC_FILE_RANGE_WRITE) {
345		ret = filemap_fdatawrite_range(mapping, offset, endbyte);
 
 
 
 
 
 
 
346		if (ret < 0)
347			goto out_put;
348	}
349
350	if (flags & SYNC_FILE_RANGE_WAIT_AFTER)
351		ret = filemap_fdatawait_range(mapping, offset, endbyte);
352
353out_put:
354	fput_light(file, fput_needed);
355out:
356	return ret;
357}
358#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
359asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes,
360				    long flags)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
361{
362	return SYSC_sync_file_range((int) fd, offset, nbytes,
363				    (unsigned int) flags);
364}
365SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range);
366#endif
367
368/* It would be nice if people remember that not all the world's an i386
369   when they introduce new system calls */
370SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags,
371				 loff_t offset, loff_t nbytes)
372{
373	return sys_sync_file_range(fd, offset, nbytes, flags);
374}
375#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
376asmlinkage long SyS_sync_file_range2(long fd, long flags,
377				     loff_t offset, loff_t nbytes)
378{
379	return SYSC_sync_file_range2((int) fd, (unsigned int) flags,
380				     offset, nbytes);
381}
382SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2);
383#endif
v5.4
  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}