[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
 * 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)
{
	/* Avoid doing twice syncing and cache pruning for quota sync */
	if (!wait) {
		writeout_quota_sb(sb, -1);
		writeback_inodes_sb(sb);
	} else {
		sync_quota_sb(sb, -1);
		sync_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)
			__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;
}

/**
 * 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	21	/*
d8a8559c JA	22	* Do the filesystem syncing work. For simple filesystems
	23	* writeback_inodes_sb(sb) just dirties buffers with inodes so we have to
	24	* submit IO for these buffers via __sync_blockdev(). This also speeds up the
	25	* wait == 1 case since in that case write_inode() functions do
	26	* sync_dirty_buffer() and thus effectively write one block at a time.
c15c54f5	27	*/
60b0680f	28	static int __sync_filesystem(struct super_block *sb, int wait)
c15c54f5	29	{
c3f8a40c	30	/* Avoid doing twice syncing and cache pruning for quota sync */
d8a8559c	31	if (!wait) {
c3f8a40c	32	writeout_quota_sb(sb, -1);
d8a8559c JA	33	writeback_inodes_sb(sb);
d8a8559c JA	34	} else {
c3f8a40c	35	sync_quota_sb(sb, -1);
d8a8559c JA	36	sync_inodes_sb(sb);
d8a8559c JA	37	}
c15c54f5 JK	38	if (sb->s_op->sync_fs)
	39	sb->s_op->sync_fs(sb, wait);
	40	return __sync_blockdev(sb->s_bdev, wait);
	41	}
	42
	43	/*
	44	* Write out and wait upon all dirty data associated with this
	45	* superblock. Filesystem data as well as the underlying block
	46	* device. Takes the superblock lock.
	47	*/
60b0680f	48	int sync_filesystem(struct super_block *sb)
c15c54f5 JK	49	{
	50	int ret;
	51
5af7926f CH	52	/*
	53	* We need to be protected against the filesystem going from
	54	* r/o to r/w or vice versa.
	55	*/
	56	WARN_ON(!rwsem_is_locked(&sb->s_umount));
	57
	58	/*
	59	* No point in syncing out anything if the filesystem is read-only.
	60	*/
	61	if (sb->s_flags & MS_RDONLY)
	62	return 0;
	63
60b0680f	64	ret = __sync_filesystem(sb, 0);
c15c54f5 JK	65	if (ret < 0)
c15c54f5 JK	66	return ret;
60b0680f	67	return __sync_filesystem(sb, 1);
c15c54f5	68	}
60b0680f	69	EXPORT_SYMBOL_GPL(sync_filesystem);
c15c54f5 JK	70
	71	/*
	72	* Sync all the data for all the filesystems (called by sys_sync() and
	73	* emergency sync)
	74	*
	75	* This operation is careful to avoid the livelock which could easily happen
	76	* if two or more filesystems are being continuously dirtied. s_need_sync
	77	* is used only here. We set it against all filesystems and then clear it as
	78	* we sync them. So redirtied filesystems are skipped.
	79	*
	80	* But if process A is currently running sync_filesystems and then process B
	81	* calls sync_filesystems as well, process B will set all the s_need_sync
	82	* flags again, which will cause process A to resync everything. Fix that with
	83	* a local mutex.
	84	*/
	85	static void sync_filesystems(int wait)
	86	{
	87	struct super_block *sb;
	88	static DEFINE_MUTEX(mutex);
	89
	90	mutex_lock(&mutex); /* Could be down_interruptible */
	91	spin_lock(&sb_lock);
5af7926f	92	list_for_each_entry(sb, &super_blocks, s_list)
c15c54f5	93	sb->s_need_sync = 1;
c15c54f5 JK	94
	95	restart:
	96	list_for_each_entry(sb, &super_blocks, s_list) {
	97	if (!sb->s_need_sync)
	98	continue;
	99	sb->s_need_sync = 0;
c15c54f5 JK	100	sb->s_count++;
c15c54f5 JK	101	spin_unlock(&sb_lock);
5af7926f	102
c15c54f5	103	down_read(&sb->s_umount);
5af7926f	104	if (!(sb->s_flags & MS_RDONLY) && sb->s_root)
60b0680f	105	__sync_filesystem(sb, wait);
c15c54f5	106	up_read(&sb->s_umount);
5af7926f	107
c15c54f5 JK	108	/* restart only when sb is no longer on the list */
	109	spin_lock(&sb_lock);
	110	if (__put_super_and_need_restart(sb))
	111	goto restart;
	112	}
	113	spin_unlock(&sb_lock);
	114	mutex_unlock(&mutex);
	115	}
	116
3beab0b4 ZY	117	/*
	118	* sync everything. Start out by waking pdflush, because that writes back
	119	* all queues in parallel.
	120	*/
5cee5815	121	SYSCALL_DEFINE0(sync)
cf9a2ae8	122	{
03ba3782	123	wakeup_flusher_threads(0);
5cee5815 JK	124	sync_filesystems(0);
5cee5815 JK	125	sync_filesystems(1);
cf9a2ae8 DH	126	if (unlikely(laptop_mode))
cf9a2ae8 DH	127	laptop_sync_completion();
cf9a2ae8 DH	128	return 0;
	129	}
	130
a2a9537a JA	131	static void do_sync_work(struct work_struct *work)
a2a9537a JA	132	{
5cee5815 JK	133	/*
	134	* Sync twice to reduce the possibility we skipped some inodes / pages
	135	* because they were temporarily locked
	136	*/
	137	sync_filesystems(0);
	138	sync_filesystems(0);
	139	printk("Emergency Sync complete\n");
a2a9537a JA	140	kfree(work);
	141	}
	142
cf9a2ae8 DH	143	void emergency_sync(void)
cf9a2ae8 DH	144	{
a2a9537a JA	145	struct work_struct *work;
	146
	147	work = kmalloc(sizeof(*work), GFP_ATOMIC);
	148	if (work) {
	149	INIT_WORK(work, do_sync_work);
	150	schedule_work(work);
	151	}
cf9a2ae8 DH	152	}
	153
	154	/*
	155	* Generic function to fsync a file.
	156	*
	157	* filp may be NULL if called via the msync of a vma.
	158	*/
	159	int file_fsync(struct file filp, struct dentry dentry, int datasync)
	160	{
	161	struct inode * inode = dentry->d_inode;
	162	struct super_block * sb;
	163	int ret, err;
	164
	165	/* sync the inode to buffers */
	166	ret = write_inode_now(inode, 0);
	167
	168	/* sync the superblock to buffers */
	169	sb = inode->i_sb;
762873c2	170	if (sb->s_dirt && sb->s_op->write_super)
cf9a2ae8	171	sb->s_op->write_super(sb);
cf9a2ae8 DH	172
	173	/* .. finally sync the buffers to disk */
	174	err = sync_blockdev(sb->s_bdev);
	175	if (!ret)
	176	ret = err;
	177	return ret;
	178	}
	179
4c728ef5 CH	180	/**
	181	* vfs_fsync - perform a fsync or fdatasync on a file
	182	* @file: file to sync
	183	* @dentry: dentry of @file
	184	* @data: only perform a fdatasync operation
	185	*
	186	* Write back data and metadata for @file to disk. If @datasync is
	187	* set only metadata needed to access modified file data is written.
	188	*
	189	* In case this function is called from nfsd @file may be %NULL and
	190	* only @dentry is set. This can only happen when the filesystem
	191	* implements the export_operations API.
	192	*/
	193	int vfs_fsync(struct file file, struct dentry dentry, int datasync)
cf9a2ae8	194	{
4c728ef5 CH	195	const struct file_operations *fop;
	196	struct address_space *mapping;
	197	int err, ret;
	198
	199	/*
	200	* Get mapping and operations from the file in case we have
	201	* as file, or get the default values for them in case we
	202	* don't have a struct file available. Damn nfsd..
	203	*/
	204	if (file) {
	205	mapping = file->f_mapping;
	206	fop = file->f_op;
	207	} else {
	208	mapping = dentry->d_inode->i_mapping;
	209	fop = dentry->d_inode->i_fop;
	210	}
cf9a2ae8	211
4c728ef5	212	if (!fop \|\| !fop->fsync) {
cf9a2ae8 DH	213	ret = -EINVAL;
	214	goto out;
	215	}
	216
	217	ret = filemap_fdatawrite(mapping);
	218
	219	/*
	220	* We need to protect against concurrent writers, which could cause
	221	* livelocks in fsync_buffers_list().
	222	*/
	223	mutex_lock(&mapping->host->i_mutex);
4c728ef5	224	err = fop->fsync(file, dentry, datasync);
cf9a2ae8 DH	225	if (!ret)
	226	ret = err;
	227	mutex_unlock(&mapping->host->i_mutex);
	228	err = filemap_fdatawait(mapping);
	229	if (!ret)
	230	ret = err;
	231	out:
	232	return ret;
	233	}
4c728ef5	234	EXPORT_SYMBOL(vfs_fsync);
cf9a2ae8	235
4c728ef5	236	static int do_fsync(unsigned int fd, int datasync)
cf9a2ae8 DH	237	{
	238	struct file *file;
	239	int ret = -EBADF;
	240
	241	file = fget(fd);
	242	if (file) {
4c728ef5	243	ret = vfs_fsync(file, file->f_path.dentry, datasync);
cf9a2ae8 DH	244	fput(file);
	245	}
	246	return ret;
	247	}
	248
a5f8fa9e	249	SYSCALL_DEFINE1(fsync, unsigned int, fd)
cf9a2ae8	250	{
4c728ef5	251	return do_fsync(fd, 0);
cf9a2ae8 DH	252	}
cf9a2ae8 DH	253
a5f8fa9e	254	SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
cf9a2ae8	255	{
4c728ef5	256	return do_fsync(fd, 1);
cf9a2ae8 DH	257	}
cf9a2ae8 DH	258
f79e2abb AM	259	/*
	260	* sys_sync_file_range() permits finely controlled syncing over a segment of
	261	* a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
	262	* zero then sys_sync_file_range() will operate from offset out to EOF.
	263	*
	264	* The flag bits are:
	265	*
	266	* SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
	267	* before performing the write.
	268	*
	269	* SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
cce77081 PM	270	* range which are not presently under writeback. Note that this may block for
cce77081 PM	271	* significant periods due to exhaustion of disk request structures.
f79e2abb AM	272	*
	273	* SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
	274	* after performing the write.
	275	*
	276	* Useful combinations of the flag bits are:
	277	*
	278	* SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE: ensures that all pages
	279	* in the range which were dirty on entry to sys_sync_file_range() are placed
	280	* under writeout. This is a start-write-for-data-integrity operation.
	281	*
	282	* SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
	283	* are not presently under writeout. This is an asynchronous flush-to-disk
	284	* operation. Not suitable for data integrity operations.
	285	*
	286	* SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
	287	* completion of writeout of all pages in the range. This will be used after an
	288	* earlier SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE operation to wait
	289	* for that operation to complete and to return the result.
	290	*
	291	* SYNC_FILE_RANGE_WAIT_BEFORE\|SYNC_FILE_RANGE_WRITE\|SYNC_FILE_RANGE_WAIT_AFTER:
	292	* a traditional sync() operation. This is a write-for-data-integrity operation
	293	* which will ensure that all pages in the range which were dirty on entry to
	294	* sys_sync_file_range() are committed to disk.
	295	*
	296	*
	297	* SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
	298	* I/O errors or ENOSPC conditions and will return those to the caller, after
	299	* clearing the EIO and ENOSPC flags in the address_space.
	300	*
	301	* It should be noted that none of these operations write out the file's
	302	* metadata. So unless the application is strictly performing overwrites of
	303	* already-instantiated disk blocks, there are no guarantees here that the data
	304	* will be available after a crash.
	305	*/
6673e0c3 HC	306	SYSCALL_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes,
6673e0c3 HC	307	unsigned int flags)
f79e2abb AM	308	{
	309	int ret;
	310	struct file *file;
	311	loff_t endbyte; /* inclusive */
	312	int fput_needed;
	313	umode_t i_mode;
	314
	315	ret = -EINVAL;
	316	if (flags & ~VALID_FLAGS)
	317	goto out;
	318
	319	endbyte = offset + nbytes;
	320
	321	if ((s64)offset < 0)
	322	goto out;
	323	if ((s64)endbyte < 0)
	324	goto out;
	325	if (endbyte < offset)
	326	goto out;
	327
	328	if (sizeof(pgoff_t) == 4) {
	329	if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
	330	/*
	331	* The range starts outside a 32 bit machine's
	332	* pagecache addressing capabilities. Let it "succeed"
	333	*/
	334	ret = 0;
	335	goto out;
	336	}
	337	if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
	338	/*
	339	* Out to EOF
	340	*/
	341	nbytes = 0;
	342	}
	343	}
	344
	345	if (nbytes == 0)
111ebb6e	346	endbyte = LLONG_MAX;
f79e2abb AM	347	else
	348	endbyte--; /* inclusive */
	349
	350	ret = -EBADF;
	351	file = fget_light(fd, &fput_needed);
	352	if (!file)
	353	goto out;
	354
0f7fc9e4	355	i_mode = file->f_path.dentry->d_inode->i_mode;
f79e2abb AM	356	ret = -ESPIPE;
	357	if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
	358	!S_ISLNK(i_mode))
	359	goto out_put;
	360
ef51c976	361	ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags);
f79e2abb AM	362	out_put:
	363	fput_light(file, fput_needed);
	364	out:
	365	return ret;
	366	}
6673e0c3 HC	367	#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
	368	asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes,
	369	long flags)
	370	{
	371	return SYSC_sync_file_range((int) fd, offset, nbytes,
	372	(unsigned int) flags);
	373	}
	374	SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range);
	375	#endif
f79e2abb	376
edd5cd4a DW	377	/* It would be nice if people remember that not all the world's an i386
edd5cd4a DW	378	when they introduce new system calls */
6673e0c3 HC	379	SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags,
6673e0c3 HC	380	loff_t offset, loff_t nbytes)
edd5cd4a DW	381	{
	382	return sys_sync_file_range(fd, offset, nbytes, flags);
	383	}
6673e0c3 HC	384	#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
	385	asmlinkage long SyS_sync_file_range2(long fd, long flags,
	386	loff_t offset, loff_t nbytes)
	387	{
	388	return SYSC_sync_file_range2((int) fd, (unsigned int) flags,
	389	offset, nbytes);
	390	}
	391	SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2);
	392	#endif
edd5cd4a	393
f79e2abb AM	394	/*
	395	* `endbyte' is inclusive
	396	*/
5b04aa3a MF	397	int do_sync_mapping_range(struct address_space *mapping, loff_t offset,
5b04aa3a MF	398	loff_t endbyte, unsigned int flags)
f79e2abb AM	399	{
f79e2abb AM	400	int ret;
f79e2abb	401
f79e2abb AM	402	if (!mapping) {
	403	ret = -EINVAL;
	404	goto out;
	405	}
	406
	407	ret = 0;
	408	if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
	409	ret = wait_on_page_writeback_range(mapping,
	410	offset >> PAGE_CACHE_SHIFT,
	411	endbyte >> PAGE_CACHE_SHIFT);
	412	if (ret < 0)
	413	goto out;
	414	}
	415
	416	if (flags & SYNC_FILE_RANGE_WRITE) {
	417	ret = __filemap_fdatawrite_range(mapping, offset, endbyte,
ee53a891	418	WB_SYNC_ALL);
f79e2abb AM	419	if (ret < 0)
	420	goto out;
	421	}
	422
	423	if (flags & SYNC_FILE_RANGE_WAIT_AFTER) {
	424	ret = wait_on_page_writeback_range(mapping,
	425	offset >> PAGE_CACHE_SHIFT,
	426	endbyte >> PAGE_CACHE_SHIFT);
	427	}
	428	out:
	429	return ret;
	430	}
5b04aa3a	431	EXPORT_SYMBOL_GPL(do_sync_mapping_range);