[deliverable/linux.git] / fs / sync.c

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

#include <linux/kernel.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/module.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 "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 sync_inodes_sb(sb, 0)
 * 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)
{
	/* Avoid doing twice syncing and cache pruning for quota sync */
	if (!wait)
		writeout_quota_sb(sb, -1);
	else
		sync_quota_sb(sb, -1);
	sync_inodes_sb(sb, wait);
	lock_super(sb);
	if (sb->s_dirt && sb->s_op->write_super)
		sb->s_op->write_super(sb);
	unlock_super(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);

/*
 * Sync all the data for all the filesystems (called by sys_sync() and
 * emergency sync)
 *
 * This operation is careful to avoid the livelock which could easily happen
 * if two or more filesystems are being continuously dirtied.  s_need_sync
 * is used only here.  We set it against all filesystems and then clear it as
 * we sync them.  So redirtied filesystems are skipped.
 *
 * But if process A is currently running sync_filesystems and then process B
 * calls sync_filesystems as well, process B will set all the s_need_sync
 * flags again, which will cause process A to resync everything.  Fix that with
 * a local mutex.
 */
static void sync_filesystems(int wait)
{
	struct super_block *sb;
	static DEFINE_MUTEX(mutex);

	mutex_lock(&mutex);		/* Could be down_interruptible */
	spin_lock(&sb_lock);
	list_for_each_entry(sb, &super_blocks, s_list)
		sb->s_need_sync = 1;

restart:
	list_for_each_entry(sb, &super_blocks, s_list) {
		if (!sb->s_need_sync)
			continue;
		sb->s_need_sync = 0;
		sb->s_count++;
		spin_unlock(&sb_lock);

		down_read(&sb->s_umount);
		if (!(sb->s_flags & MS_RDONLY) && sb->s_root)
			__sync_filesystem(sb, wait);
		up_read(&sb->s_umount);

		/* restart only when sb is no longer on the list */
		spin_lock(&sb_lock);
		if (__put_super_and_need_restart(sb))
			goto restart;
	}
	spin_unlock(&sb_lock);
	mutex_unlock(&mutex);
}

SYSCALL_DEFINE0(sync)
{
	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);
	}
}

/*
 * Generic function to fsync a file.
 *
 * filp may be NULL if called via the msync of a vma.
 */
int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
{
	struct inode * inode = dentry->d_inode;
	struct super_block * sb;
	int ret, err;

	/* sync the inode to buffers */
	ret = write_inode_now(inode, 0);

	/* sync the superblock to buffers */
	sb = inode->i_sb;
	lock_super(sb);
	if (sb->s_dirt && sb->s_op->write_super)
		sb->s_op->write_super(sb);
	unlock_super(sb);

	/* .. finally sync the buffers to disk */
	err = sync_blockdev(sb->s_bdev);
	if (!ret)
		ret = err;
	return ret;
}

/**
 * vfs_fsync - perform a fsync or fdatasync on a file
 * @file:		file to sync
 * @dentry:		dentry of @file
 * @data:		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.
 *
 * In case this function is called from nfsd @file may be %NULL and
 * only @dentry is set.  This can only happen when the filesystem
 * implements the export_operations API.
 */
int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)
{
	const struct file_operations *fop;
	struct address_space *mapping;
	int err, ret;

	/*
	 * Get mapping and operations from the file in case we have
	 * as file, or get the default values for them in case we
	 * don't have a struct file available.  Damn nfsd..
	 */
	if (file) {
		mapping = file->f_mapping;
		fop = file->f_op;
	} else {
		mapping = dentry->d_inode->i_mapping;
		fop = dentry->d_inode->i_fop;
	}

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

	ret = filemap_fdatawrite(mapping);

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

/*
 * 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;
	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;

	ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags);
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

/*
 * `endbyte' is inclusive
 */
int do_sync_mapping_range(struct address_space *mapping, loff_t offset,
			  loff_t endbyte, unsigned int flags)
{
	int ret;

	if (!mapping) {
		ret = -EINVAL;
		goto out;
	}

	ret = 0;
	if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
		ret = wait_on_page_writeback_range(mapping,
					offset >> PAGE_CACHE_SHIFT,
					endbyte >> PAGE_CACHE_SHIFT);
		if (ret < 0)
			goto out;
	}

	if (flags & SYNC_FILE_RANGE_WRITE) {
		ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
						WB_SYNC_ALL);
		if (ret < 0)
			goto out;
	}

	if (flags & SYNC_FILE_RANGE_WAIT_AFTER) {
		ret = wait_on_page_writeback_range(mapping,
					offset >> PAGE_CACHE_SHIFT,
					endbyte >> PAGE_CACHE_SHIFT);
	}
out:
	return ret;
}
EXPORT_SYMBOL_GPL(do_sync_mapping_range);
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>
	8	#include <linux/module.h>
914e2637	9	#include <linux/sched.h>
f79e2abb AM	10	#include <linux/writeback.h>
	11	#include <linux/syscalls.h>
	12	#include <linux/linkage.h>
	13	#include <linux/pagemap.h>
cf9a2ae8 DH	14	#include <linux/quotaops.h>
cf9a2ae8 DH	15	#include <linux/buffer_head.h>
5a3e5cb8	16	#include "internal.h"
f79e2abb AM	17
	18	#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE\| \
	19	SYNC_FILE_RANGE_WAIT_AFTER)
	20
c15c54f5 JK	21	/*
	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.
	27	*/
60b0680f	28	static int __sync_filesystem(struct super_block *sb, int wait)
c15c54f5	29	{
c3f8a40c JK	30	/* Avoid doing twice syncing and cache pruning for quota sync */
	31	if (!wait)
	32	writeout_quota_sb(sb, -1);
	33	else
	34	sync_quota_sb(sb, -1);
c15c54f5 JK	35	sync_inodes_sb(sb, wait);
	36	lock_super(sb);
	37	if (sb->s_dirt && sb->s_op->write_super)
	38	sb->s_op->write_super(sb);
	39	unlock_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);
	43	}
	44
	45	/*
	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.
	49	*/
60b0680f	50	int sync_filesystem(struct super_block *sb)
c15c54f5 JK	51	{
	52	int ret;
	53
5af7926f CH	54	/*
	55	* We need to be protected against the filesystem going from
	56	* r/o to r/w or vice versa.
	57	*/
	58	WARN_ON(!rwsem_is_locked(&sb->s_umount));
	59
	60	/*
	61	* No point in syncing out anything if the filesystem is read-only.
	62	*/
	63	if (sb->s_flags & MS_RDONLY)
	64	return 0;
	65
60b0680f	66	ret = __sync_filesystem(sb, 0);
c15c54f5 JK	67	if (ret < 0)
c15c54f5 JK	68	return ret;
60b0680f	69	return __sync_filesystem(sb, 1);
c15c54f5	70	}
60b0680f	71	EXPORT_SYMBOL_GPL(sync_filesystem);
c15c54f5 JK	72
	73	/*
	74	* Sync all the data for all the filesystems (called by sys_sync() and
	75	* emergency sync)
	76	*
	77	* This operation is careful to avoid the livelock which could easily happen
	78	* if two or more filesystems are being continuously dirtied. s_need_sync
	79	* is used only here. We set it against all filesystems and then clear it as
	80	* we sync them. So redirtied filesystems are skipped.
	81	*
	82	* But if process A is currently running sync_filesystems and then process B
	83	* calls sync_filesystems as well, process B will set all the s_need_sync
	84	* flags again, which will cause process A to resync everything. Fix that with
	85	* a local mutex.
	86	*/
	87	static void sync_filesystems(int wait)
	88	{
	89	struct super_block *sb;
	90	static DEFINE_MUTEX(mutex);
	91
	92	mutex_lock(&mutex); /* Could be down_interruptible */
	93	spin_lock(&sb_lock);
5af7926f	94	list_for_each_entry(sb, &super_blocks, s_list)
c15c54f5	95	sb->s_need_sync = 1;
c15c54f5 JK	96
	97	restart:
	98	list_for_each_entry(sb, &super_blocks, s_list) {
	99	if (!sb->s_need_sync)
	100	continue;
	101	sb->s_need_sync = 0;
c15c54f5 JK	102	sb->s_count++;
c15c54f5 JK	103	spin_unlock(&sb_lock);
5af7926f	104
c15c54f5	105	down_read(&sb->s_umount);
5af7926f	106	if (!(sb->s_flags & MS_RDONLY) && sb->s_root)
60b0680f	107	__sync_filesystem(sb, wait);
c15c54f5	108	up_read(&sb->s_umount);
5af7926f	109
c15c54f5 JK	110	/* restart only when sb is no longer on the list */
	111	spin_lock(&sb_lock);
	112	if (__put_super_and_need_restart(sb))
	113	goto restart;
	114	}
	115	spin_unlock(&sb_lock);
	116	mutex_unlock(&mutex);
	117	}
	118
5cee5815	119	SYSCALL_DEFINE0(sync)
cf9a2ae8	120	{
5cee5815 JK	121	sync_filesystems(0);
5cee5815 JK	122	sync_filesystems(1);
cf9a2ae8 DH	123	if (unlikely(laptop_mode))
cf9a2ae8 DH	124	laptop_sync_completion();
cf9a2ae8 DH	125	return 0;
	126	}
	127
a2a9537a JA	128	static void do_sync_work(struct work_struct *work)
a2a9537a JA	129	{
5cee5815 JK	130	/*
	131	* Sync twice to reduce the possibility we skipped some inodes / pages
	132	* because they were temporarily locked
	133	*/
	134	sync_filesystems(0);
	135	sync_filesystems(0);
	136	printk("Emergency Sync complete\n");
a2a9537a JA	137	kfree(work);
	138	}
	139
cf9a2ae8 DH	140	void emergency_sync(void)
cf9a2ae8 DH	141	{
a2a9537a JA	142	struct work_struct *work;
	143
	144	work = kmalloc(sizeof(*work), GFP_ATOMIC);
	145	if (work) {
	146	INIT_WORK(work, do_sync_work);
	147	schedule_work(work);
	148	}
cf9a2ae8 DH	149	}
	150
	151	/*
	152	* Generic function to fsync a file.
	153	*
	154	* filp may be NULL if called via the msync of a vma.
	155	*/
	156	int file_fsync(struct file filp, struct dentry dentry, int datasync)
	157	{
	158	struct inode * inode = dentry->d_inode;
	159	struct super_block * sb;
	160	int ret, err;
	161
	162	/* sync the inode to buffers */
	163	ret = write_inode_now(inode, 0);
	164
	165	/* sync the superblock to buffers */
	166	sb = inode->i_sb;
	167	lock_super(sb);
762873c2	168	if (sb->s_dirt && sb->s_op->write_super)
cf9a2ae8 DH	169	sb->s_op->write_super(sb);
	170	unlock_super(sb);
	171
	172	/* .. finally sync the buffers to disk */
	173	err = sync_blockdev(sb->s_bdev);
	174	if (!ret)
	175	ret = err;
	176	return ret;
	177	}
	178
4c728ef5 CH	179	/**
	180	* vfs_fsync - perform a fsync or fdatasync on a file
	181	* @file: file to sync
	182	* @dentry: dentry of @file
	183	* @data: only perform a fdatasync operation
	184	*
	185	* Write back data and metadata for @file to disk. If @datasync is
	186	* set only metadata needed to access modified file data is written.
	187	*
	188	* In case this function is called from nfsd @file may be %NULL and
	189	* only @dentry is set. This can only happen when the filesystem
	190	* implements the export_operations API.
	191	*/
	192	int vfs_fsync(struct file file, struct dentry dentry, int datasync)
cf9a2ae8	193	{
4c728ef5 CH	194	const struct file_operations *fop;
	195	struct address_space *mapping;
	196	int err, ret;
	197
	198	/*
	199	* Get mapping and operations from the file in case we have
	200	* as file, or get the default values for them in case we
	201	* don't have a struct file available. Damn nfsd..
	202	*/
	203	if (file) {
	204	mapping = file->f_mapping;
	205	fop = file->f_op;
	206	} else {
	207	mapping = dentry->d_inode->i_mapping;
	208	fop = dentry->d_inode->i_fop;
	209	}
cf9a2ae8	210
4c728ef5	211	if (!fop \|\| !fop->fsync) {
cf9a2ae8 DH	212	ret = -EINVAL;
	213	goto out;
	214	}
	215
	216	ret = filemap_fdatawrite(mapping);
	217
	218	/*
	219	* We need to protect against concurrent writers, which could cause
	220	* livelocks in fsync_buffers_list().
	221	*/
	222	mutex_lock(&mapping->host->i_mutex);
4c728ef5	223	err = fop->fsync(file, dentry, datasync);
cf9a2ae8 DH	224	if (!ret)
	225	ret = err;
	226	mutex_unlock(&mapping->host->i_mutex);
	227	err = filemap_fdatawait(mapping);
	228	if (!ret)
	229	ret = err;
	230	out:
	231	return ret;
	232	}
4c728ef5	233	EXPORT_SYMBOL(vfs_fsync);
cf9a2ae8	234
4c728ef5	235	static int do_fsync(unsigned int fd, int datasync)
cf9a2ae8 DH	236	{
	237	struct file *file;
	238	int ret = -EBADF;
	239
	240	file = fget(fd);
	241	if (file) {
4c728ef5	242	ret = vfs_fsync(file, file->f_path.dentry, datasync);
cf9a2ae8 DH	243	fput(file);
	244	}
	245	return ret;
	246	}
	247
a5f8fa9e	248	SYSCALL_DEFINE1(fsync, unsigned int, fd)
cf9a2ae8	249	{
4c728ef5	250	return do_fsync(fd, 0);
cf9a2ae8 DH	251	}
cf9a2ae8 DH	252
a5f8fa9e	253	SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
cf9a2ae8	254	{
4c728ef5	255	return do_fsync(fd, 1);
cf9a2ae8 DH	256	}
cf9a2ae8 DH	257
f79e2abb AM	258	/*
	259	* sys_sync_file_range() permits finely controlled syncing over a segment of
	260	* a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
	261	* zero then sys_sync_file_range() will operate from offset out to EOF.
	262	*
	263	* The flag bits are:
	264	*
	265	* SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
	266	* before performing the write.
	267	*
	268	* SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
cce77081 PM	269	* range which are not presently under writeback. Note that this may block for
cce77081 PM	270	* significant periods due to exhaustion of disk request structures.
f79e2abb AM	271	*
	272	* SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
	273	* after performing the write.
	274	*
	275	* Useful combinations of the flag bits are:
	276	*
	277	* SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE: ensures that all pages
	278	* in the range which were dirty on entry to sys_sync_file_range() are placed
	279	* under writeout. This is a start-write-for-data-integrity operation.
	280	*
	281	* SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
	282	* are not presently under writeout. This is an asynchronous flush-to-disk
	283	* operation. Not suitable for data integrity operations.
	284	*
	285	* SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
	286	* completion of writeout of all pages in the range. This will be used after an
	287	* earlier SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE operation to wait
	288	* for that operation to complete and to return the result.
	289	*
	290	* SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE\|SYNC_FILE_RANGE_WAIT_AFTER:
	291	* a traditional sync() operation. This is a write-for-data-integrity operation
	292	* which will ensure that all pages in the range which were dirty on entry to
	293	* sys_sync_file_range() are committed to disk.
	294	*
	295	*
	296	* SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
	297	* I/O errors or ENOSPC conditions and will return those to the caller, after
	298	* clearing the EIO and ENOSPC flags in the address_space.
	299	*
	300	* It should be noted that none of these operations write out the file's
	301	* metadata. So unless the application is strictly performing overwrites of
	302	* already-instantiated disk blocks, there are no guarantees here that the data
	303	* will be available after a crash.
	304	*/
6673e0c3 HC	305	SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes,
6673e0c3 HC	306	unsigned int flags)
f79e2abb AM	307	{
	308	int ret;
	309	struct file *file;
	310	loff_t endbyte; /* inclusive */
	311	int fput_needed;
	312	umode_t i_mode;
	313
	314	ret = -EINVAL;
	315	if (flags & ~VALID_FLAGS)
	316	goto out;
	317
	318	endbyte = offset + nbytes;
	319
	320	if ((s64)offset < 0)
	321	goto out;
	322	if ((s64)endbyte < 0)
	323	goto out;
	324	if (endbyte < offset)
	325	goto out;
	326
	327	if (sizeof(pgoff_t) == 4) {
	328	if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
	329	/*
	330	* The range starts outside a 32 bit machine's
	331	* pagecache addressing capabilities. Let it "succeed"
	332	*/
	333	ret = 0;
	334	goto out;
	335	}
	336	if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
	337	/*
	338	* Out to EOF
	339	*/
	340	nbytes = 0;
	341	}
	342	}
	343
	344	if (nbytes == 0)
111ebb6e	345	endbyte = LLONG_MAX;
f79e2abb AM	346	else
	347	endbyte--; /* inclusive */
	348
	349	ret = -EBADF;
	350	file = fget_light(fd, &fput_needed);
	351	if (!file)
	352	goto out;
	353
0f7fc9e4	354	i_mode = file->f_path.dentry->d_inode->i_mode;
f79e2abb AM	355	ret = -ESPIPE;
	356	if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
	357	!S_ISLNK(i_mode))
	358	goto out_put;
	359
ef51c976	360	ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags);
f79e2abb AM	361	out_put:
	362	fput_light(file, fput_needed);
	363	out:
	364	return ret;
	365	}
6673e0c3 HC	366	#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
	367	asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes,
	368	long flags)
	369	{
	370	return SYSC_sync_file_range((int) fd, offset, nbytes,
	371	(unsigned int) flags);
	372	}
	373	SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range);
	374	#endif
f79e2abb	375
edd5cd4a DW	376	/* It would be nice if people remember that not all the world's an i386
edd5cd4a DW	377	when they introduce new system calls */
6673e0c3 HC	378	SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags,
6673e0c3 HC	379	loff_t offset, loff_t nbytes)
edd5cd4a DW	380	{
	381	return sys_sync_file_range(fd, offset, nbytes, flags);
	382	}
6673e0c3 HC	383	#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
	384	asmlinkage long SyS_sync_file_range2(long fd, long flags,
	385	loff_t offset, loff_t nbytes)
	386	{
	387	return SYSC_sync_file_range2((int) fd, (unsigned int) flags,
	388	offset, nbytes);
	389	}
	390	SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2);
	391	#endif
edd5cd4a	392
f79e2abb AM	393	/*
	394	* `endbyte' is inclusive
	395	*/
5b04aa3a MF	396	int do_sync_mapping_range(struct address_space *mapping, loff_t offset,
5b04aa3a MF	397	loff_t endbyte, unsigned int flags)
f79e2abb AM	398	{
f79e2abb AM	399	int ret;
f79e2abb	400
f79e2abb AM	401	if (!mapping) {
	402	ret = -EINVAL;
	403	goto out;
	404	}
	405
	406	ret = 0;
	407	if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
	408	ret = wait_on_page_writeback_range(mapping,
	409	offset >> PAGE_CACHE_SHIFT,
	410	endbyte >> PAGE_CACHE_SHIFT);
	411	if (ret < 0)
	412	goto out;
	413	}
	414
	415	if (flags & SYNC_FILE_RANGE_WRITE) {
	416	ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
ee53a891	417	WB_SYNC_ALL);
f79e2abb AM	418	if (ret < 0)
	419	goto out;
	420	}
	421
	422	if (flags & SYNC_FILE_RANGE_WAIT_AFTER) {
	423	ret = wait_on_page_writeback_range(mapping,
	424	offset >> PAGE_CACHE_SHIFT,
	425	endbyte >> PAGE_CACHE_SHIFT);
	426	}
	427	out:
	428	return ret;
	429	}
5b04aa3a	430	EXPORT_SYMBOL_GPL(do_sync_mapping_range);