[linux.git] / fs / sync.c

/*
 * High-level sync()-related operations
 */

#include <linux/kernel.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/namei.h>
#include <linux/sched.h>
#include <linux/writeback.h>
#include <linux/syscalls.h>
#include <linux/linkage.h>
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/buffer_head.h>
#include <linux/backing-dev.h>
#include "internal.h"

#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
			SYNC_FILE_RANGE_WAIT_AFTER)

/*
 * Do the filesystem syncing work. For simple filesystems
 * writeback_inodes_sb(sb) just dirties buffers with inodes so we have to
 * submit IO for these buffers via __sync_blockdev(). This also speeds up the
 * wait == 1 case since in that case write_inode() functions do
 * sync_dirty_buffer() and thus effectively write one block at a time.
 */
static int __sync_filesystem(struct super_block *sb, int wait)
{
	/*
	 * This should be safe, as we require bdi backing to actually
	 * write out data in the first place
	 */
	if (sb->s_bdi == &noop_backing_dev_info)
		return 0;

	if (sb->s_qcop && sb->s_qcop->quota_sync)
		sb->s_qcop->quota_sync(sb, -1, wait);

	if (wait)
		sync_inodes_sb(sb);
	else
		writeback_inodes_sb(sb);

	if (sb->s_op->sync_fs)
		sb->s_op->sync_fs(sb, wait);
	return __sync_blockdev(sb->s_bdev, wait);
}

/*
 * Write out and wait upon all dirty data associated with this
 * superblock.  Filesystem data as well as the underlying block
 * device.  Takes the superblock lock.
 */
int sync_filesystem(struct super_block *sb)
{
	int ret;

	/*
	 * We need to be protected against the filesystem going from
	 * r/o to r/w or vice versa.
	 */
	WARN_ON(!rwsem_is_locked(&sb->s_umount));

	/*
	 * No point in syncing out anything if the filesystem is read-only.
	 */
	if (sb->s_flags & MS_RDONLY)
		return 0;

	ret = __sync_filesystem(sb, 0);
	if (ret < 0)
		return ret;
	return __sync_filesystem(sb, 1);
}
EXPORT_SYMBOL_GPL(sync_filesystem);

static void sync_one_sb(struct super_block *sb, void *arg)
{
	if (!(sb->s_flags & MS_RDONLY))
		__sync_filesystem(sb, *(int *)arg);
}
/*
 * Sync all the data for all the filesystems (called by sys_sync() and
 * emergency sync)
 */
static void sync_filesystems(int wait)
{
	iterate_supers(sync_one_sb, &wait);
}

/*
 * sync everything.  Start out by waking pdflush, because that writes back
 * all queues in parallel.
 */
SYSCALL_DEFINE0(sync)
{
	wakeup_flusher_threads(0);
	sync_filesystems(0);
	sync_filesystems(1);
	if (unlikely(laptop_mode))
		laptop_sync_completion();
	return 0;
}

static void do_sync_work(struct work_struct *work)
{
	/*
	 * Sync twice to reduce the possibility we skipped some inodes / pages
	 * because they were temporarily locked
	 */
	sync_filesystems(0);
	sync_filesystems(0);
	printk("Emergency Sync complete\n");
	kfree(work);
}

void emergency_sync(void)
{
	struct work_struct *work;

	work = kmalloc(sizeof(*work), GFP_ATOMIC);
	if (work) {
		INIT_WORK(work, do_sync_work);
		schedule_work(work);
	}
}

/*
 * sync a single super
 */
SYSCALL_DEFINE1(syncfs, int, fd)
{
	struct file *file;
	struct super_block *sb;
	int ret;
	int fput_needed;

	file = fget_light(fd, &fput_needed);
	if (!file)
		return -EBADF;
	sb = file->f_dentry->d_sb;

	down_read(&sb->s_umount);
	ret = sync_filesystem(sb);
	up_read(&sb->s_umount);

	fput_light(file, fput_needed);
	return ret;
}

/**
 * vfs_fsync_range - helper to sync a range of data & metadata to disk
 * @file:		file to sync
 * @start:		offset in bytes of the beginning of data range to sync
 * @end:		offset in bytes of the end of data range (inclusive)
 * @datasync:		perform only datasync
 *
 * Write back data in range @start..@end and metadata for @file to disk.  If
 * @datasync is set only metadata needed to access modified file data is
 * written.
 */
int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync)
{
	struct address_space *mapping = file->f_mapping;
	int err, ret;

	if (!file->f_op || !file->f_op->fsync) {
		ret = -EINVAL;
		goto out;
	}

	ret = filemap_write_and_wait_range(mapping, start, end);

	/*
	 * We need to protect against concurrent writers, which could cause
	 * livelocks in fsync_buffers_list().
	 */
	mutex_lock(&mapping->host->i_mutex);
	err = file->f_op->fsync(file, datasync);
	if (!ret)
		ret = err;
	mutex_unlock(&mapping->host->i_mutex);

out:
	return ret;
}
EXPORT_SYMBOL(vfs_fsync_range);

/**
 * vfs_fsync - perform a fsync or fdatasync on a file
 * @file:		file to sync
 * @datasync:		only perform a fdatasync operation
 *
 * Write back data and metadata for @file to disk.  If @datasync is
 * set only metadata needed to access modified file data is written.
 */
int vfs_fsync(struct file *file, int datasync)
{
	return vfs_fsync_range(file, 0, LLONG_MAX, datasync);
}
EXPORT_SYMBOL(vfs_fsync);

static int do_fsync(unsigned int fd, int datasync)
{
	struct file *file;
	int ret = -EBADF;

	file = fget(fd);
	if (file) {
		ret = vfs_fsync(file, datasync);
		fput(file);
	}
	return ret;
}

SYSCALL_DEFINE1(fsync, unsigned int, fd)
{
	return do_fsync(fd, 0);
}

SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
{
	return do_fsync(fd, 1);
}

/**
 * generic_write_sync - perform syncing after a write if file / inode is sync
 * @file:	file to which the write happened
 * @pos:	offset where the write started
 * @count:	length of the write
 *
 * This is just a simple wrapper about our general syncing function.
 */
int generic_write_sync(struct file *file, loff_t pos, loff_t count)
{
	if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
		return 0;
	return vfs_fsync_range(file, pos, pos + count - 1,
			       (file->f_flags & __O_SYNC) ? 0 : 1);
}
EXPORT_SYMBOL(generic_write_sync);

/*
 * sys_sync_file_range() permits finely controlled syncing over a segment of
 * a file in the range offset .. (offset+nbytes-1) inclusive.  If nbytes is
 * zero then sys_sync_file_range() will operate from offset out to EOF.
 *
 * The flag bits are:
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
 * before performing the write.
 *
 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
 * range which are not presently under writeback. Note that this may block for
 * significant periods due to exhaustion of disk request structures.
 *
 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
 * after performing the write.
 *
 * Useful combinations of the flag bits are:
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
 * in the range which were dirty on entry to sys_sync_file_range() are placed
 * under writeout.  This is a start-write-for-data-integrity operation.
 *
 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
 * are not presently under writeout.  This is an asynchronous flush-to-disk
 * operation.  Not suitable for data integrity operations.
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
 * completion of writeout of all pages in the range.  This will be used after an
 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
 * for that operation to complete and to return the result.
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
 * a traditional sync() operation.  This is a write-for-data-integrity operation
 * which will ensure that all pages in the range which were dirty on entry to
 * sys_sync_file_range() are committed to disk.
 *
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
 * I/O errors or ENOSPC conditions and will return those to the caller, after
 * clearing the EIO and ENOSPC flags in the address_space.
 *
 * It should be noted that none of these operations write out the file's
 * metadata.  So unless the application is strictly performing overwrites of
 * already-instantiated disk blocks, there are no guarantees here that the data
 * will be available after a crash.
 */
SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes,
				unsigned int flags)
{
	int ret;
	struct file *file;
	struct address_space *mapping;
	loff_t endbyte;			/* inclusive */
	int fput_needed;
	umode_t i_mode;

	ret = -EINVAL;
	if (flags & ~VALID_FLAGS)
		goto out;

	endbyte = offset + nbytes;

	if ((s64)offset < 0)
		goto out;
	if ((s64)endbyte < 0)
		goto out;
	if (endbyte < offset)
		goto out;

	if (sizeof(pgoff_t) == 4) {
		if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
			/*
			 * The range starts outside a 32 bit machine's
			 * pagecache addressing capabilities.  Let it "succeed"
			 */
			ret = 0;
			goto out;
		}
		if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
			/*
			 * Out to EOF
			 */
			nbytes = 0;
		}
	}

	if (nbytes == 0)
		endbyte = LLONG_MAX;
	else
		endbyte--;		/* inclusive */

	ret = -EBADF;
	file = fget_light(fd, &fput_needed);
	if (!file)
		goto out;

	i_mode = file->f_path.dentry->d_inode->i_mode;
	ret = -ESPIPE;
	if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
			!S_ISLNK(i_mode))
		goto out_put;

	mapping = file->f_mapping;
	if (!mapping) {
		ret = -EINVAL;
		goto out_put;
	}

	ret = 0;
	if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
		ret = filemap_fdatawait_range(mapping, offset, endbyte);
		if (ret < 0)
			goto out_put;
	}

	if (flags & SYNC_FILE_RANGE_WRITE) {
		ret = filemap_fdatawrite_range(mapping, offset, endbyte);
		if (ret < 0)
			goto out_put;
	}

	if (flags & SYNC_FILE_RANGE_WAIT_AFTER)
		ret = filemap_fdatawait_range(mapping, offset, endbyte);

out_put:
	fput_light(file, fput_needed);
out:
	return ret;
}
#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes,
				    long flags)
{
	return SYSC_sync_file_range((int) fd, offset, nbytes,
				    (unsigned int) flags);
}
SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range);
#endif

/* It would be nice if people remember that not all the world's an i386
   when they introduce new system calls */
SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags,
				 loff_t offset, loff_t nbytes)
{
	return sys_sync_file_range(fd, offset, nbytes, flags);
}
#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
asmlinkage long SyS_sync_file_range2(long fd, long flags,
				     loff_t offset, loff_t nbytes)
{
	return SYSC_sync_file_range2((int) fd, (unsigned int) flags,
				     offset, nbytes);
}
SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2);
#endif
Commit	Line	Data
f79e2abb AM	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>
f79e2abb	9	#include <linux/module.h>
b7ed78f5	10	#include <linux/namei.h>
914e2637	11	#include <linux/sched.h>
f79e2abb AM	12	#include <linux/writeback.h>
	13	#include <linux/syscalls.h>
	14	#include <linux/linkage.h>
	15	#include <linux/pagemap.h>
cf9a2ae8 DH	16	#include <linux/quotaops.h>
cf9a2ae8 DH	17	#include <linux/buffer_head.h>
5129a469	18	#include <linux/backing-dev.h>
5a3e5cb8	19	#include "internal.h"
f79e2abb AM	20
	21	#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE\| \
	22	SYNC_FILE_RANGE_WAIT_AFTER)
	23
c15c54f5	24	/*
d8a8559c JA	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.
c15c54f5	30	*/
60b0680f	31	static int __sync_filesystem(struct super_block *sb, int wait)
c15c54f5	32	{
32a88aa1 JA	33	/*
	34	* This should be safe, as we require bdi backing to actually
	35	* write out data in the first place
	36	*/
95f28604	37	if (sb->s_bdi == &noop_backing_dev_info)
32a88aa1 JA	38	return 0;
32a88aa1 JA	39
5fb324ad CH	40	if (sb->s_qcop && sb->s_qcop->quota_sync)
	41	sb->s_qcop->quota_sync(sb, -1, wait);
	42
	43	if (wait)
d8a8559c	44	sync_inodes_sb(sb);
5fb324ad	45	else
0e3c9a22	46	writeback_inodes_sb(sb);
5fb324ad	47
c15c54f5 JK	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	*/
60b0680f	58	int sync_filesystem(struct super_block *sb)
c15c54f5 JK	59	{
	60	int ret;
	61
5af7926f CH	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
60b0680f	74	ret = __sync_filesystem(sb, 0);
c15c54f5 JK	75	if (ret < 0)
c15c54f5 JK	76	return ret;
60b0680f	77	return __sync_filesystem(sb, 1);
c15c54f5	78	}
60b0680f	79	EXPORT_SYMBOL_GPL(sync_filesystem);
c15c54f5	80
01a05b33 AV	81	static void sync_one_sb(struct super_block sb, void arg)
01a05b33 AV	82	{
95f28604	83	if (!(sb->s_flags & MS_RDONLY))
01a05b33 AV	84	__sync_filesystem(sb, (int )arg);
01a05b33 AV	85	}
c15c54f5 JK	86	/*
	87	* Sync all the data for all the filesystems (called by sys_sync() and
	88	* emergency sync)
c15c54f5 JK	89	*/
	90	static void sync_filesystems(int wait)
	91	{
01a05b33	92	iterate_supers(sync_one_sb, &wait);
c15c54f5 JK	93	}
c15c54f5 JK	94
3beab0b4 ZY	95	/*
	96	* sync everything. Start out by waking pdflush, because that writes back
	97	* all queues in parallel.
	98	*/
5cee5815	99	SYSCALL_DEFINE0(sync)
cf9a2ae8	100	{
03ba3782	101	wakeup_flusher_threads(0);
5cee5815 JK	102	sync_filesystems(0);
5cee5815 JK	103	sync_filesystems(1);
cf9a2ae8 DH	104	if (unlikely(laptop_mode))
cf9a2ae8 DH	105	laptop_sync_completion();
cf9a2ae8 DH	106	return 0;
	107	}
	108
a2a9537a JA	109	static void do_sync_work(struct work_struct *work)
a2a9537a JA	110	{
5cee5815 JK	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");
a2a9537a JA	118	kfree(work);
	119	}
	120
cf9a2ae8 DH	121	void emergency_sync(void)
cf9a2ae8 DH	122	{
a2a9537a JA	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	}
cf9a2ae8 DH	130	}
cf9a2ae8 DH	131
b7ed78f5 SW	132	/*
	133	* sync a single super
	134	*/
	135	SYSCALL_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
4c728ef5	155	/**
148f948b	156	* vfs_fsync_range - helper to sync a range of data & metadata to disk
4c728ef5	157	* @file: file to sync
148f948b JK	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
4c728ef5	161	*
148f948b JK	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.
4c728ef5	165	*/
8018ab05	166	int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync)
cf9a2ae8	167	{
8018ab05	168	struct address_space *mapping = file->f_mapping;
4c728ef5 CH	169	int err, ret;
4c728ef5 CH	170
8018ab05	171	if (!file->f_op \|\| !file->f_op->fsync) {
cf9a2ae8 DH	172	ret = -EINVAL;
	173	goto out;
	174	}
	175
2daea67e	176	ret = filemap_write_and_wait_range(mapping, start, end);
cf9a2ae8 DH	177
	178	/*
	179	* We need to protect against concurrent writers, which could cause
	180	* livelocks in fsync_buffers_list().
	181	*/
	182	mutex_lock(&mapping->host->i_mutex);
7ea80859	183	err = file->f_op->fsync(file, datasync);
cf9a2ae8 DH	184	if (!ret)
	185	ret = err;
	186	mutex_unlock(&mapping->host->i_mutex);
148f948b	187
cf9a2ae8 DH	188	out:
	189	return ret;
	190	}
148f948b JK	191	EXPORT_SYMBOL(vfs_fsync_range);
	192
	193	/**
	194	* vfs_fsync - perform a fsync or fdatasync on a file
	195	* @file: file to sync
148f948b JK	196	* @datasync: only perform a fdatasync operation
	197	*
	198	* Write back data and metadata for @file to disk. If @datasync is
	199	* set only metadata needed to access modified file data is written.
148f948b	200	*/
8018ab05	201	int vfs_fsync(struct file *file, int datasync)
148f948b	202	{
8018ab05	203	return vfs_fsync_range(file, 0, LLONG_MAX, datasync);
148f948b	204	}
4c728ef5	205	EXPORT_SYMBOL(vfs_fsync);
cf9a2ae8	206
4c728ef5	207	static int do_fsync(unsigned int fd, int datasync)
cf9a2ae8 DH	208	{
	209	struct file *file;
	210	int ret = -EBADF;
	211
	212	file = fget(fd);
	213	if (file) {
8018ab05	214	ret = vfs_fsync(file, datasync);
cf9a2ae8 DH	215	fput(file);
	216	}
	217	return ret;
	218	}
	219
a5f8fa9e	220	SYSCALL_DEFINE1(fsync, unsigned int, fd)
cf9a2ae8	221	{
4c728ef5	222	return do_fsync(fd, 0);
cf9a2ae8 DH	223	}
cf9a2ae8 DH	224
a5f8fa9e	225	SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
cf9a2ae8	226	{
4c728ef5	227	return do_fsync(fd, 1);
cf9a2ae8 DH	228	}
cf9a2ae8 DH	229
148f948b JK	230	/**
	231	* generic_write_sync - perform syncing after a write if file / inode is sync
	232	* @file: file to which the write happened
	233	* @pos: offset where the write started
	234	* @count: length of the write
	235	*
	236	* This is just a simple wrapper about our general syncing function.
	237	*/
	238	int generic_write_sync(struct file *file, loff_t pos, loff_t count)
	239	{
6b2f3d1f	240	if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
148f948b	241	return 0;
8018ab05	242	return vfs_fsync_range(file, pos, pos + count - 1,
6b2f3d1f	243	(file->f_flags & __O_SYNC) ? 0 : 1);
148f948b JK	244	}
	245	EXPORT_SYMBOL(generic_write_sync);
	246
f79e2abb AM	247	/*
	248	* sys_sync_file_range() permits finely controlled syncing over a segment of
	249	* a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
	250	* zero then sys_sync_file_range() will operate from offset out to EOF.
	251	*
	252	* The flag bits are:
	253	*
	254	* SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
	255	* before performing the write.
	256	*
	257	* SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
cce77081 PM	258	* range which are not presently under writeback. Note that this may block for
cce77081 PM	259	* significant periods due to exhaustion of disk request structures.
f79e2abb AM	260	*
	261	* SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
	262	* after performing the write.
	263	*
	264	* Useful combinations of the flag bits are:
	265	*
	266	* SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE: ensures that all pages
	267	* in the range which were dirty on entry to sys_sync_file_range() are placed
	268	* under writeout. This is a start-write-for-data-integrity operation.
	269	*
	270	* SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
	271	* are not presently under writeout. This is an asynchronous flush-to-disk
	272	* operation. Not suitable for data integrity operations.
	273	*
	274	* SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
	275	* completion of writeout of all pages in the range. This will be used after an
	276	* earlier SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE operation to wait
	277	* for that operation to complete and to return the result.
	278	*
	279	* SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE\|SYNC_FILE_RANGE_WAIT_AFTER:
	280	* a traditional sync() operation. This is a write-for-data-integrity operation
	281	* which will ensure that all pages in the range which were dirty on entry to
	282	* sys_sync_file_range() are committed to disk.
	283	*
	284	*
	285	* SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
	286	* I/O errors or ENOSPC conditions and will return those to the caller, after
	287	* clearing the EIO and ENOSPC flags in the address_space.
	288	*
	289	* It should be noted that none of these operations write out the file's
	290	* metadata. So unless the application is strictly performing overwrites of
	291	* already-instantiated disk blocks, there are no guarantees here that the data
	292	* will be available after a crash.
	293	*/
6673e0c3 HC	294	SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes,
6673e0c3 HC	295	unsigned int flags)
f79e2abb AM	296	{
	297	int ret;
	298	struct file *file;
7a0ad10c	299	struct address_space *mapping;
f79e2abb AM	300	loff_t endbyte; /* inclusive */
	301	int fput_needed;
	302	umode_t i_mode;
	303
	304	ret = -EINVAL;
	305	if (flags & ~VALID_FLAGS)
	306	goto out;
	307
	308	endbyte = offset + nbytes;
	309
	310	if ((s64)offset < 0)
	311	goto out;
	312	if ((s64)endbyte < 0)
	313	goto out;
	314	if (endbyte < offset)
	315	goto out;
	316
	317	if (sizeof(pgoff_t) == 4) {
	318	if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
	319	/*
	320	* The range starts outside a 32 bit machine's
	321	* pagecache addressing capabilities. Let it "succeed"
	322	*/
	323	ret = 0;
	324	goto out;
	325	}
	326	if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
	327	/*
	328	* Out to EOF
	329	*/
	330	nbytes = 0;
	331	}
	332	}
	333
	334	if (nbytes == 0)
111ebb6e	335	endbyte = LLONG_MAX;
f79e2abb AM	336	else
	337	endbyte--; /* inclusive */
	338
	339	ret = -EBADF;
	340	file = fget_light(fd, &fput_needed);
	341	if (!file)
	342	goto out;
	343
0f7fc9e4	344	i_mode = file->f_path.dentry->d_inode->i_mode;
f79e2abb AM	345	ret = -ESPIPE;
	346	if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
	347	!S_ISLNK(i_mode))
	348	goto out_put;
	349
7a0ad10c CH	350	mapping = file->f_mapping;
	351	if (!mapping) {
	352	ret = -EINVAL;
	353	goto out_put;
	354	}
	355
	356	ret = 0;
	357	if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
	358	ret = filemap_fdatawait_range(mapping, offset, endbyte);
	359	if (ret < 0)
	360	goto out_put;
	361	}
	362
	363	if (flags & SYNC_FILE_RANGE_WRITE) {
	364	ret = filemap_fdatawrite_range(mapping, offset, endbyte);
	365	if (ret < 0)
	366	goto out_put;
	367	}
	368
	369	if (flags & SYNC_FILE_RANGE_WAIT_AFTER)
	370	ret = filemap_fdatawait_range(mapping, offset, endbyte);
	371
f79e2abb AM	372	out_put:
	373	fput_light(file, fput_needed);
	374	out:
	375	return ret;
	376	}
6673e0c3 HC	377	#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
	378	asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes,
	379	long flags)
	380	{
	381	return SYSC_sync_file_range((int) fd, offset, nbytes,
	382	(unsigned int) flags);
	383	}
	384	SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range);
	385	#endif
f79e2abb	386
edd5cd4a DW	387	/* It would be nice if people remember that not all the world's an i386
edd5cd4a DW	388	when they introduce new system calls */
6673e0c3 HC	389	SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags,
6673e0c3 HC	390	loff_t offset, loff_t nbytes)
edd5cd4a DW	391	{
	392	return sys_sync_file_range(fd, offset, nbytes, flags);
	393	}
6673e0c3 HC	394	#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
	395	asmlinkage long SyS_sync_file_range2(long fd, long flags,
	396	loff_t offset, loff_t nbytes)
	397	{
	398	return SYSC_sync_file_range2((int) fd, (unsigned int) flags,
	399	offset, nbytes);
	400	}
	401	SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2);
	402	#endif