[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/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 __fsync_super(struct super_block *sb, int wait)
{
	vfs_dq_sync(sb);
	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 fsync_super(struct super_block *sb)
{
	int ret;

	ret = __fsync_super(sb, 0);
	if (ret < 0)
		return ret;
	return __fsync_super(sb, 1);
}
EXPORT_SYMBOL_GPL(fsync_super);

/*
 * 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) {
		if (sb->s_flags & MS_RDONLY)
			continue;
		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;
		if (sb->s_flags & MS_RDONLY)
			continue;	/* hm.  Was remounted r/o meanwhile */
		sb->s_count++;
		spin_unlock(&sb_lock);
		down_read(&sb->s_umount);
		if (sb->s_root)
			__fsync_super(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	*/
	28	static int __fsync_super(struct super_block *sb, int wait)
	29	{
	30	vfs_dq_sync(sb);
	31	sync_inodes_sb(sb, wait);
	32	lock_super(sb);
	33	if (sb->s_dirt && sb->s_op->write_super)
	34	sb->s_op->write_super(sb);
	35	unlock_super(sb);
	36	if (sb->s_op->sync_fs)
	37	sb->s_op->sync_fs(sb, wait);
	38	return __sync_blockdev(sb->s_bdev, wait);
	39	}
	40
	41	/*
	42	* Write out and wait upon all dirty data associated with this
	43	* superblock. Filesystem data as well as the underlying block
	44	* device. Takes the superblock lock.
	45	*/
	46	int fsync_super(struct super_block *sb)
	47	{
	48	int ret;
	49
	50	ret = __fsync_super(sb, 0);
	51	if (ret < 0)
	52	return ret;
	53	return __fsync_super(sb, 1);
	54	}
	55	EXPORT_SYMBOL_GPL(fsync_super);
	56
	57	/*
	58	* Sync all the data for all the filesystems (called by sys_sync() and
	59	* emergency sync)
	60	*
	61	* This operation is careful to avoid the livelock which could easily happen
	62	* if two or more filesystems are being continuously dirtied. s_need_sync
	63	* is used only here. We set it against all filesystems and then clear it as
	64	* we sync them. So redirtied filesystems are skipped.
	65	*
	66	* But if process A is currently running sync_filesystems and then process B
	67	* calls sync_filesystems as well, process B will set all the s_need_sync
	68	* flags again, which will cause process A to resync everything. Fix that with
	69	* a local mutex.
	70	*/
	71	static void sync_filesystems(int wait)
	72	{
	73	struct super_block *sb;
	74	static DEFINE_MUTEX(mutex);
	75
	76	mutex_lock(&mutex); /* Could be down_interruptible */
	77	spin_lock(&sb_lock);
	78	list_for_each_entry(sb, &super_blocks, s_list) {
	79	if (sb->s_flags & MS_RDONLY)
	80	continue;
	81	sb->s_need_sync = 1;
	82	}
	83
	84	restart:
85	list_for_each_entry(sb, &super_blocks, s_list) {
86	if (!sb->s_need_sync)
87	continue;
88	sb->s_need_sync = 0;
89	if (sb->s_flags & MS_RDONLY)
90	continue; /* hm. Was remounted r/o meanwhile */
91	sb->s_count++;
92	spin_unlock(&sb_lock);
93	down_read(&sb->s_umount);
94	if (sb->s_root)
95	__fsync_super(sb, wait);
96	up_read(&sb->s_umount);
97	/* restart only when sb is no longer on the list */
98	spin_lock(&sb_lock);
99	if (__put_super_and_need_restart(sb))
100	goto restart;
101	}
102	spin_unlock(&sb_lock);
103	mutex_unlock(&mutex);
104	}
105
5cee5815	106	SYSCALL_DEFINE0(sync)
cf9a2ae8	107	{
5cee5815 JK	108	sync_filesystems(0);
5cee5815 JK	109	sync_filesystems(1);
cf9a2ae8 DH	110	if (unlikely(laptop_mode))
cf9a2ae8 DH	111	laptop_sync_completion();
cf9a2ae8 DH	112	return 0;
	113	}
	114
a2a9537a JA	115	static void do_sync_work(struct work_struct *work)
a2a9537a JA	116	{
5cee5815 JK	117	/*
	118	* Sync twice to reduce the possibility we skipped some inodes / pages
	119	* because they were temporarily locked
	120	*/
	121	sync_filesystems(0);
	122	sync_filesystems(0);
	123	printk("Emergency Sync complete\n");
a2a9537a JA	124	kfree(work);
	125	}
	126
cf9a2ae8 DH	127	void emergency_sync(void)
cf9a2ae8 DH	128	{
a2a9537a JA	129	struct work_struct *work;
	130
	131	work = kmalloc(sizeof(*work), GFP_ATOMIC);
	132	if (work) {
	133	INIT_WORK(work, do_sync_work);
	134	schedule_work(work);
	135	}
cf9a2ae8 DH	136	}
	137
	138	/*
	139	* Generic function to fsync a file.
	140	*
	141	* filp may be NULL if called via the msync of a vma.
	142	*/
	143	int file_fsync(struct file filp, struct dentry dentry, int datasync)
	144	{
	145	struct inode * inode = dentry->d_inode;
	146	struct super_block * sb;
	147	int ret, err;
	148
	149	/* sync the inode to buffers */
	150	ret = write_inode_now(inode, 0);
	151
	152	/* sync the superblock to buffers */
	153	sb = inode->i_sb;
	154	lock_super(sb);
762873c2	155	if (sb->s_dirt && sb->s_op->write_super)
cf9a2ae8 DH	156	sb->s_op->write_super(sb);
	157	unlock_super(sb);
	158
	159	/* .. finally sync the buffers to disk */
	160	err = sync_blockdev(sb->s_bdev);
	161	if (!ret)
	162	ret = err;
	163	return ret;
	164	}
	165
4c728ef5 CH	166	/**
	167	* vfs_fsync - perform a fsync or fdatasync on a file
	168	* @file: file to sync
	169	* @dentry: dentry of @file
	170	* @data: only perform a fdatasync operation
	171	*
	172	* Write back data and metadata for @file to disk. If @datasync is
	173	* set only metadata needed to access modified file data is written.
	174	*
	175	* In case this function is called from nfsd @file may be %NULL and
	176	* only @dentry is set. This can only happen when the filesystem
	177	* implements the export_operations API.
	178	*/
	179	int vfs_fsync(struct file file, struct dentry dentry, int datasync)
cf9a2ae8	180	{
4c728ef5 CH	181	const struct file_operations *fop;
	182	struct address_space *mapping;
	183	int err, ret;
	184
	185	/*
	186	* Get mapping and operations from the file in case we have
	187	* as file, or get the default values for them in case we
	188	* don't have a struct file available. Damn nfsd..
	189	*/
	190	if (file) {
	191	mapping = file->f_mapping;
	192	fop = file->f_op;
	193	} else {
	194	mapping = dentry->d_inode->i_mapping;
	195	fop = dentry->d_inode->i_fop;
	196	}
cf9a2ae8	197
4c728ef5	198	if (!fop \|\| !fop->fsync) {
cf9a2ae8 DH	199	ret = -EINVAL;
	200	goto out;
	201	}
	202
	203	ret = filemap_fdatawrite(mapping);
	204
	205	/*
	206	* We need to protect against concurrent writers, which could cause
	207	* livelocks in fsync_buffers_list().
	208	*/
	209	mutex_lock(&mapping->host->i_mutex);
4c728ef5	210	err = fop->fsync(file, dentry, datasync);
cf9a2ae8 DH	211	if (!ret)
	212	ret = err;
	213	mutex_unlock(&mapping->host->i_mutex);
	214	err = filemap_fdatawait(mapping);
	215	if (!ret)
	216	ret = err;
	217	out:
	218	return ret;
	219	}
4c728ef5	220	EXPORT_SYMBOL(vfs_fsync);
cf9a2ae8	221
4c728ef5	222	static int do_fsync(unsigned int fd, int datasync)
cf9a2ae8 DH	223	{
	224	struct file *file;
	225	int ret = -EBADF;
	226
	227	file = fget(fd);
	228	if (file) {
4c728ef5	229	ret = vfs_fsync(file, file->f_path.dentry, datasync);
cf9a2ae8 DH	230	fput(file);
	231	}
	232	return ret;
	233	}
	234
a5f8fa9e	235	SYSCALL_DEFINE1(fsync, unsigned int, fd)
cf9a2ae8	236	{
4c728ef5	237	return do_fsync(fd, 0);
cf9a2ae8 DH	238	}
cf9a2ae8 DH	239
a5f8fa9e	240	SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
cf9a2ae8	241	{
4c728ef5	242	return do_fsync(fd, 1);
cf9a2ae8 DH	243	}
cf9a2ae8 DH	244
f79e2abb AM	245	/*
	246	* sys_sync_file_range() permits finely controlled syncing over a segment of
	247	* a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
	248	* zero then sys_sync_file_range() will operate from offset out to EOF.
	249	*
	250	* The flag bits are:
	251	*
	252	* SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
	253	* before performing the write.
	254	*
	255	* SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
cce77081 PM	256	* range which are not presently under writeback. Note that this may block for
cce77081 PM	257	* significant periods due to exhaustion of disk request structures.
f79e2abb AM	258	*
	259	* SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
	260	* after performing the write.
	261	*
	262	* Useful combinations of the flag bits are:
	263	*
	264	* SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE: ensures that all pages
	265	* in the range which were dirty on entry to sys_sync_file_range() are placed
	266	* under writeout. This is a start-write-for-data-integrity operation.
	267	*
	268	* SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
	269	* are not presently under writeout. This is an asynchronous flush-to-disk
	270	* operation. Not suitable for data integrity operations.
	271	*
	272	* SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
	273	* completion of writeout of all pages in the range. This will be used after an
	274	* earlier SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE operation to wait
	275	* for that operation to complete and to return the result.
	276	*
	277	* SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE\|SYNC_FILE_RANGE_WAIT_AFTER:
	278	* a traditional sync() operation. This is a write-for-data-integrity operation
	279	* which will ensure that all pages in the range which were dirty on entry to
	280	* sys_sync_file_range() are committed to disk.
	281	*
	282	*
	283	* SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
	284	* I/O errors or ENOSPC conditions and will return those to the caller, after
	285	* clearing the EIO and ENOSPC flags in the address_space.
	286	*
	287	* It should be noted that none of these operations write out the file's
	288	* metadata. So unless the application is strictly performing overwrites of
	289	* already-instantiated disk blocks, there are no guarantees here that the data
	290	* will be available after a crash.
	291	*/
6673e0c3 HC	292	SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes,
6673e0c3 HC	293	unsigned int flags)
f79e2abb AM	294	{
	295	int ret;
	296	struct file *file;
	297	loff_t endbyte; /* inclusive */
	298	int fput_needed;
	299	umode_t i_mode;
	300
	301	ret = -EINVAL;
	302	if (flags & ~VALID_FLAGS)
	303	goto out;
	304
	305	endbyte = offset + nbytes;
	306
	307	if ((s64)offset < 0)
	308	goto out;
	309	if ((s64)endbyte < 0)
	310	goto out;
	311	if (endbyte < offset)
	312	goto out;
	313
	314	if (sizeof(pgoff_t) == 4) {
	315	if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
	316	/*
	317	* The range starts outside a 32 bit machine's
	318	* pagecache addressing capabilities. Let it "succeed"
	319	*/
	320	ret = 0;
	321	goto out;
	322	}
	323	if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
	324	/*
	325	* Out to EOF
	326	*/
	327	nbytes = 0;
	328	}
	329	}
	330
	331	if (nbytes == 0)
111ebb6e	332	endbyte = LLONG_MAX;
f79e2abb AM	333	else
	334	endbyte--; /* inclusive */
	335
	336	ret = -EBADF;
	337	file = fget_light(fd, &fput_needed);
	338	if (!file)
	339	goto out;
	340
0f7fc9e4	341	i_mode = file->f_path.dentry->d_inode->i_mode;
f79e2abb AM	342	ret = -ESPIPE;
	343	if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
	344	!S_ISLNK(i_mode))
	345	goto out_put;
	346
ef51c976	347	ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags);
f79e2abb AM	348	out_put:
	349	fput_light(file, fput_needed);
	350	out:
	351	return ret;
	352	}
6673e0c3 HC	353	#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
	354	asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes,
	355	long flags)
	356	{
	357	return SYSC_sync_file_range((int) fd, offset, nbytes,
	358	(unsigned int) flags);
	359	}
	360	SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range);
	361	#endif
f79e2abb	362
edd5cd4a DW	363	/* It would be nice if people remember that not all the world's an i386
edd5cd4a DW	364	when they introduce new system calls */
6673e0c3 HC	365	SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags,
6673e0c3 HC	366	loff_t offset, loff_t nbytes)
edd5cd4a DW	367	{
	368	return sys_sync_file_range(fd, offset, nbytes, flags);
	369	}
6673e0c3 HC	370	#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
	371	asmlinkage long SyS_sync_file_range2(long fd, long flags,
	372	loff_t offset, loff_t nbytes)
	373	{
	374	return SYSC_sync_file_range2((int) fd, (unsigned int) flags,
	375	offset, nbytes);
	376	}
	377	SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2);
	378	#endif
edd5cd4a	379
f79e2abb AM	380	/*
	381	* `endbyte' is inclusive
	382	*/
5b04aa3a MF	383	int do_sync_mapping_range(struct address_space *mapping, loff_t offset,
5b04aa3a MF	384	loff_t endbyte, unsigned int flags)
f79e2abb AM	385	{
f79e2abb AM	386	int ret;
f79e2abb	387
f79e2abb AM	388	if (!mapping) {
	389	ret = -EINVAL;
	390	goto out;
	391	}
	392
	393	ret = 0;
	394	if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
	395	ret = wait_on_page_writeback_range(mapping,
	396	offset >> PAGE_CACHE_SHIFT,
	397	endbyte >> PAGE_CACHE_SHIFT);
	398	if (ret < 0)
	399	goto out;
	400	}
	401
	402	if (flags & SYNC_FILE_RANGE_WRITE) {
	403	ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
ee53a891	404	WB_SYNC_ALL);
f79e2abb AM	405	if (ret < 0)
	406	goto out;
	407	}
	408
	409	if (flags & SYNC_FILE_RANGE_WAIT_AFTER) {
	410	ret = wait_on_page_writeback_range(mapping,
	411	offset >> PAGE_CACHE_SHIFT,
	412	endbyte >> PAGE_CACHE_SHIFT);
	413	}
	414	out:
	415	return ret;
	416	}
5b04aa3a	417	EXPORT_SYMBOL_GPL(do_sync_mapping_range);