[net-next-2.6.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/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
 * 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)
		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);

/*
 * 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 && sb->s_bdi)
			__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);
}

/*
 * 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);
	}
}

/*
 * 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;
	if (sb->s_dirt && sb->s_op->write_super)
		sb->s_op->write_super(sb);

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

/**
 * vfs_fsync_range - helper to sync a range of data & metadata to disk
 * @file:		file to sync
 * @dentry:		dentry of @file
 * @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.
 *
 * 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_range(struct file *file, struct dentry *dentry, loff_t start,
		    loff_t end, 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_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 = fop->fsync(file, dentry, 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
 * @dentry:		dentry of @file
 * @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.
 *
 * 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)
{
	return vfs_fsync_range(file, dentry, 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, 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);
}

/**
 * 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, file->f_path.dentry, 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>
914e2637	10	#include <linux/sched.h>
f79e2abb AM	11	#include <linux/writeback.h>
	12	#include <linux/syscalls.h>
	13	#include <linux/linkage.h>
	14	#include <linux/pagemap.h>
cf9a2ae8 DH	15	#include <linux/quotaops.h>
cf9a2ae8 DH	16	#include <linux/buffer_head.h>
5a3e5cb8	17	#include "internal.h"
f79e2abb AM	18
	19	#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE\| \
	20	SYNC_FILE_RANGE_WAIT_AFTER)
	21
c15c54f5	22	/*
d8a8559c JA	23	* Do the filesystem syncing work. For simple filesystems
	24	* writeback_inodes_sb(sb) just dirties buffers with inodes so we have to
	25	* submit IO for these buffers via __sync_blockdev(). This also speeds up the
	26	* wait == 1 case since in that case write_inode() functions do
	27	* sync_dirty_buffer() and thus effectively write one block at a time.
c15c54f5	28	*/
60b0680f	29	static int __sync_filesystem(struct super_block *sb, int wait)
c15c54f5	30	{
32a88aa1 JA	31	/*
	32	* This should be safe, as we require bdi backing to actually
	33	* write out data in the first place
	34	*/
	35	if (!sb->s_bdi)
	36	return 0;
	37
5fb324ad CH	38	if (sb->s_qcop && sb->s_qcop->quota_sync)
	39	sb->s_qcop->quota_sync(sb, -1, wait);
	40
	41	if (wait)
d8a8559c	42	sync_inodes_sb(sb);
5fb324ad CH	43	else
	44	writeback_inodes_sb(sb);
	45
c15c54f5 JK	46	if (sb->s_op->sync_fs)
	47	sb->s_op->sync_fs(sb, wait);
	48	return __sync_blockdev(sb->s_bdev, wait);
	49	}
	50
	51	/*
	52	* Write out and wait upon all dirty data associated with this
	53	* superblock. Filesystem data as well as the underlying block
	54	* device. Takes the superblock lock.
	55	*/
60b0680f	56	int sync_filesystem(struct super_block *sb)
c15c54f5 JK	57	{
	58	int ret;
	59
5af7926f CH	60	/*
	61	* We need to be protected against the filesystem going from
	62	* r/o to r/w or vice versa.
	63	*/
	64	WARN_ON(!rwsem_is_locked(&sb->s_umount));
	65
	66	/*
	67	* No point in syncing out anything if the filesystem is read-only.
	68	*/
	69	if (sb->s_flags & MS_RDONLY)
	70	return 0;
	71
60b0680f	72	ret = __sync_filesystem(sb, 0);
c15c54f5 JK	73	if (ret < 0)
c15c54f5 JK	74	return ret;
60b0680f	75	return __sync_filesystem(sb, 1);
c15c54f5	76	}
60b0680f	77	EXPORT_SYMBOL_GPL(sync_filesystem);
c15c54f5 JK	78
	79	/*
	80	* Sync all the data for all the filesystems (called by sys_sync() and
	81	* emergency sync)
	82	*
	83	* This operation is careful to avoid the livelock which could easily happen
	84	* if two or more filesystems are being continuously dirtied. s_need_sync
	85	* is used only here. We set it against all filesystems and then clear it as
	86	* we sync them. So redirtied filesystems are skipped.
	87	*
	88	* But if process A is currently running sync_filesystems and then process B
	89	* calls sync_filesystems as well, process B will set all the s_need_sync
	90	* flags again, which will cause process A to resync everything. Fix that with
	91	* a local mutex.
	92	*/
	93	static void sync_filesystems(int wait)
	94	{
	95	struct super_block *sb;
	96	static DEFINE_MUTEX(mutex);
	97
	98	mutex_lock(&mutex); /* Could be down_interruptible */
	99	spin_lock(&sb_lock);
5af7926f	100	list_for_each_entry(sb, &super_blocks, s_list)
c15c54f5	101	sb->s_need_sync = 1;
c15c54f5 JK	102
	103	restart:
	104	list_for_each_entry(sb, &super_blocks, s_list) {
	105	if (!sb->s_need_sync)
	106	continue;
	107	sb->s_need_sync = 0;
c15c54f5 JK	108	sb->s_count++;
c15c54f5 JK	109	spin_unlock(&sb_lock);
5af7926f	110
c15c54f5	111	down_read(&sb->s_umount);
32a88aa1	112	if (!(sb->s_flags & MS_RDONLY) && sb->s_root && sb->s_bdi)
60b0680f	113	__sync_filesystem(sb, wait);
c15c54f5	114	up_read(&sb->s_umount);
5af7926f	115
c15c54f5 JK	116	/* restart only when sb is no longer on the list */
	117	spin_lock(&sb_lock);
	118	if (__put_super_and_need_restart(sb))
	119	goto restart;
	120	}
	121	spin_unlock(&sb_lock);
	122	mutex_unlock(&mutex);
	123	}
	124
3beab0b4 ZY	125	/*
	126	* sync everything. Start out by waking pdflush, because that writes back
	127	* all queues in parallel.
	128	*/
5cee5815	129	SYSCALL_DEFINE0(sync)
cf9a2ae8	130	{
03ba3782	131	wakeup_flusher_threads(0);
5cee5815 JK	132	sync_filesystems(0);
5cee5815 JK	133	sync_filesystems(1);
cf9a2ae8 DH	134	if (unlikely(laptop_mode))
cf9a2ae8 DH	135	laptop_sync_completion();
cf9a2ae8 DH	136	return 0;
	137	}
	138
a2a9537a JA	139	static void do_sync_work(struct work_struct *work)
a2a9537a JA	140	{
5cee5815 JK	141	/*
	142	* Sync twice to reduce the possibility we skipped some inodes / pages
	143	* because they were temporarily locked
	144	*/
	145	sync_filesystems(0);
	146	sync_filesystems(0);
	147	printk("Emergency Sync complete\n");
a2a9537a JA	148	kfree(work);
	149	}
	150
cf9a2ae8 DH	151	void emergency_sync(void)
cf9a2ae8 DH	152	{
a2a9537a JA	153	struct work_struct *work;
	154
	155	work = kmalloc(sizeof(*work), GFP_ATOMIC);
	156	if (work) {
	157	INIT_WORK(work, do_sync_work);
	158	schedule_work(work);
	159	}
cf9a2ae8 DH	160	}
	161
	162	/*
	163	* Generic function to fsync a file.
	164	*
	165	* filp may be NULL if called via the msync of a vma.
	166	*/
	167	int file_fsync(struct file filp, struct dentry dentry, int datasync)
	168	{
	169	struct inode * inode = dentry->d_inode;
	170	struct super_block * sb;
	171	int ret, err;
	172
	173	/* sync the inode to buffers */
	174	ret = write_inode_now(inode, 0);
	175
	176	/* sync the superblock to buffers */
	177	sb = inode->i_sb;
762873c2	178	if (sb->s_dirt && sb->s_op->write_super)
cf9a2ae8	179	sb->s_op->write_super(sb);
cf9a2ae8 DH	180
	181	/* .. finally sync the buffers to disk */
	182	err = sync_blockdev(sb->s_bdev);
	183	if (!ret)
	184	ret = err;
	185	return ret;
	186	}
1fe72eaa	187	EXPORT_SYMBOL(file_fsync);
cf9a2ae8	188
4c728ef5	189	/**
148f948b	190	* vfs_fsync_range - helper to sync a range of data & metadata to disk
4c728ef5 CH	191	* @file: file to sync
4c728ef5 CH	192	* @dentry: dentry of @file
148f948b JK	193	* @start: offset in bytes of the beginning of data range to sync
	194	* @end: offset in bytes of the end of data range (inclusive)
	195	* @datasync: perform only datasync
4c728ef5	196	*
148f948b JK	197	* Write back data in range @start..@end and metadata for @file to disk. If
	198	* @datasync is set only metadata needed to access modified file data is
	199	* written.
4c728ef5 CH	200	*
	201	* In case this function is called from nfsd @file may be %NULL and
	202	* only @dentry is set. This can only happen when the filesystem
	203	* implements the export_operations API.
	204	*/
148f948b JK	205	int vfs_fsync_range(struct file file, struct dentry dentry, loff_t start,
148f948b JK	206	loff_t end, int datasync)
cf9a2ae8	207	{
4c728ef5 CH	208	const struct file_operations *fop;
	209	struct address_space *mapping;
	210	int err, ret;
	211
	212	/*
	213	* Get mapping and operations from the file in case we have
	214	* as file, or get the default values for them in case we
	215	* don't have a struct file available. Damn nfsd..
	216	*/
	217	if (file) {
	218	mapping = file->f_mapping;
	219	fop = file->f_op;
	220	} else {
	221	mapping = dentry->d_inode->i_mapping;
	222	fop = dentry->d_inode->i_fop;
	223	}
cf9a2ae8	224
4c728ef5	225	if (!fop \|\| !fop->fsync) {
cf9a2ae8 DH	226	ret = -EINVAL;
	227	goto out;
	228	}
	229
2daea67e	230	ret = filemap_write_and_wait_range(mapping, start, end);
cf9a2ae8 DH	231
	232	/*
	233	* We need to protect against concurrent writers, which could cause
	234	* livelocks in fsync_buffers_list().
	235	*/
	236	mutex_lock(&mapping->host->i_mutex);
4c728ef5	237	err = fop->fsync(file, dentry, datasync);
cf9a2ae8 DH	238	if (!ret)
	239	ret = err;
	240	mutex_unlock(&mapping->host->i_mutex);
148f948b	241
cf9a2ae8 DH	242	out:
	243	return ret;
	244	}
148f948b JK	245	EXPORT_SYMBOL(vfs_fsync_range);
	246
	247	/**
	248	* vfs_fsync - perform a fsync or fdatasync on a file
	249	* @file: file to sync
	250	* @dentry: dentry of @file
	251	* @datasync: only perform a fdatasync operation
	252	*
	253	* Write back data and metadata for @file to disk. If @datasync is
	254	* set only metadata needed to access modified file data is written.
	255	*
	256	* In case this function is called from nfsd @file may be %NULL and
	257	* only @dentry is set. This can only happen when the filesystem
	258	* implements the export_operations API.
	259	*/
	260	int vfs_fsync(struct file file, struct dentry dentry, int datasync)
	261	{
	262	return vfs_fsync_range(file, dentry, 0, LLONG_MAX, datasync);
	263	}
4c728ef5	264	EXPORT_SYMBOL(vfs_fsync);
cf9a2ae8	265
4c728ef5	266	static int do_fsync(unsigned int fd, int datasync)
cf9a2ae8 DH	267	{
	268	struct file *file;
	269	int ret = -EBADF;
	270
	271	file = fget(fd);
	272	if (file) {
4c728ef5	273	ret = vfs_fsync(file, file->f_path.dentry, datasync);
cf9a2ae8 DH	274	fput(file);
	275	}
	276	return ret;
	277	}
	278
a5f8fa9e	279	SYSCALL_DEFINE1(fsync, unsigned int, fd)
cf9a2ae8	280	{
4c728ef5	281	return do_fsync(fd, 0);
cf9a2ae8 DH	282	}
cf9a2ae8 DH	283
a5f8fa9e	284	SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
cf9a2ae8	285	{
4c728ef5	286	return do_fsync(fd, 1);
cf9a2ae8 DH	287	}
cf9a2ae8 DH	288
148f948b JK	289	/**
	290	* generic_write_sync - perform syncing after a write if file / inode is sync
	291	* @file: file to which the write happened
	292	* @pos: offset where the write started
	293	* @count: length of the write
	294	*
	295	* This is just a simple wrapper about our general syncing function.
	296	*/
	297	int generic_write_sync(struct file *file, loff_t pos, loff_t count)
	298	{
6b2f3d1f	299	if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
148f948b JK	300	return 0;
148f948b JK	301	return vfs_fsync_range(file, file->f_path.dentry, pos,
6b2f3d1f CH	302	pos + count - 1,
6b2f3d1f CH	303	(file->f_flags & __O_SYNC) ? 0 : 1);
148f948b JK	304	}
	305	EXPORT_SYMBOL(generic_write_sync);
	306
f79e2abb AM	307	/*
	308	* sys_sync_file_range() permits finely controlled syncing over a segment of
	309	* a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
	310	* zero then sys_sync_file_range() will operate from offset out to EOF.
	311	*
	312	* The flag bits are:
	313	*
	314	* SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
	315	* before performing the write.
	316	*
	317	* SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
cce77081 PM	318	* range which are not presently under writeback. Note that this may block for
cce77081 PM	319	* significant periods due to exhaustion of disk request structures.
f79e2abb AM	320	*
	321	* SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
	322	* after performing the write.
	323	*
	324	* Useful combinations of the flag bits are:
	325	*
	326	* SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE: ensures that all pages
	327	* in the range which were dirty on entry to sys_sync_file_range() are placed
	328	* under writeout. This is a start-write-for-data-integrity operation.
	329	*
	330	* SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
	331	* are not presently under writeout. This is an asynchronous flush-to-disk
	332	* operation. Not suitable for data integrity operations.
	333	*
	334	* SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
	335	* completion of writeout of all pages in the range. This will be used after an
	336	* earlier SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE operation to wait
	337	* for that operation to complete and to return the result.
	338	*
	339	* SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE\|SYNC_FILE_RANGE_WAIT_AFTER:
	340	* a traditional sync() operation. This is a write-for-data-integrity operation
	341	* which will ensure that all pages in the range which were dirty on entry to
	342	* sys_sync_file_range() are committed to disk.
	343	*
	344	*
	345	* SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
	346	* I/O errors or ENOSPC conditions and will return those to the caller, after
	347	* clearing the EIO and ENOSPC flags in the address_space.
	348	*
	349	* It should be noted that none of these operations write out the file's
	350	* metadata. So unless the application is strictly performing overwrites of
	351	* already-instantiated disk blocks, there are no guarantees here that the data
	352	* will be available after a crash.
	353	*/
6673e0c3 HC	354	SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes,
6673e0c3 HC	355	unsigned int flags)
f79e2abb AM	356	{
	357	int ret;
	358	struct file *file;
7a0ad10c	359	struct address_space *mapping;
f79e2abb AM	360	loff_t endbyte; /* inclusive */
	361	int fput_needed;
	362	umode_t i_mode;
	363
	364	ret = -EINVAL;
	365	if (flags & ~VALID_FLAGS)
	366	goto out;
	367
	368	endbyte = offset + nbytes;
	369
	370	if ((s64)offset < 0)
	371	goto out;
	372	if ((s64)endbyte < 0)
	373	goto out;
	374	if (endbyte < offset)
	375	goto out;
	376
	377	if (sizeof(pgoff_t) == 4) {
	378	if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
	379	/*
	380	* The range starts outside a 32 bit machine's
	381	* pagecache addressing capabilities. Let it "succeed"
	382	*/
	383	ret = 0;
	384	goto out;
	385	}
	386	if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
	387	/*
	388	* Out to EOF
	389	*/
	390	nbytes = 0;
	391	}
	392	}
	393
	394	if (nbytes == 0)
111ebb6e	395	endbyte = LLONG_MAX;
f79e2abb AM	396	else
	397	endbyte--; /* inclusive */
	398
	399	ret = -EBADF;
	400	file = fget_light(fd, &fput_needed);
	401	if (!file)
	402	goto out;
	403
0f7fc9e4	404	i_mode = file->f_path.dentry->d_inode->i_mode;
f79e2abb AM	405	ret = -ESPIPE;
	406	if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
	407	!S_ISLNK(i_mode))
	408	goto out_put;
	409
7a0ad10c CH	410	mapping = file->f_mapping;
	411	if (!mapping) {
	412	ret = -EINVAL;
	413	goto out_put;
	414	}
	415
	416	ret = 0;
	417	if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
	418	ret = filemap_fdatawait_range(mapping, offset, endbyte);
	419	if (ret < 0)
	420	goto out_put;
	421	}
	422
	423	if (flags & SYNC_FILE_RANGE_WRITE) {
	424	ret = filemap_fdatawrite_range(mapping, offset, endbyte);
	425	if (ret < 0)
	426	goto out_put;
	427	}
	428
	429	if (flags & SYNC_FILE_RANGE_WAIT_AFTER)
	430	ret = filemap_fdatawait_range(mapping, offset, endbyte);
	431
f79e2abb AM	432	out_put:
	433	fput_light(file, fput_needed);
	434	out:
	435	return ret;
	436	}
6673e0c3 HC	437	#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
	438	asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes,
	439	long flags)
	440	{
	441	return SYSC_sync_file_range((int) fd, offset, nbytes,
	442	(unsigned int) flags);
	443	}
	444	SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range);
	445	#endif
f79e2abb	446
edd5cd4a DW	447	/* It would be nice if people remember that not all the world's an i386
edd5cd4a DW	448	when they introduce new system calls */
6673e0c3 HC	449	SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags,
6673e0c3 HC	450	loff_t offset, loff_t nbytes)
edd5cd4a DW	451	{
	452	return sys_sync_file_range(fd, offset, nbytes, flags);
	453	}
6673e0c3 HC	454	#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
	455	asmlinkage long SyS_sync_file_range2(long fd, long flags,
	456	loff_t offset, loff_t nbytes)
	457	{
	458	return SYSC_sync_file_range2((int) fd, (unsigned int) flags,
	459	offset, nbytes);
	460	}
	461	SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2);
	462	#endif