/* * 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){	/*	 * This should be safe, as we require bdi backing to actually	 * write out data in the first place	 */	if (!sb->s_bdi)		return 0; 	/* 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 && 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_SYNC) && !IS_SYNC(file->f_mapping->host))		return 0;	return vfs_fsync_range(file, file->f_path.dentry, pos,			       pos + count - 1, 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;	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_WRAPPERSasmlinkage 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_WRAPPERSasmlinkage 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);