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/** *	touch_atime	-	update the access time *	@path: the &struct path to update *	@inode: inode to update * *	Update the accessed time on an inode and mark it for writeback. *	This function automatically handles read only file systems and media, *	as well as the "noatime" flag and inode specific "noatime" markers. */bool __atime_needs_update(const struct path *path, struct inode *inode,			  bool rcu){	struct vfsmount *mnt = path->mnt;	struct timespec now;	if (inode->i_flags & S_NOATIME)		return false;	/* Atime updates will likely cause i_uid and i_gid to be written	 * back improprely if their true value is unknown to the vfs.	 */	if (HAS_UNMAPPED_ID(inode))		return false;	if (IS_NOATIME(inode))		return false;	if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))		return false;	if (mnt->mnt_flags & MNT_NOATIME)		return false;	if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))		return false;	now = current_time(inode);	if (!relatime_need_update(path, inode, now, rcu))		return false;	if (timespec_equal(&inode->i_atime, &now))		return false;	return true;}

void touch_atime(const struct path *path){	struct vfsmount *mnt = path->mnt;	struct inode *inode = d_inode(path->dentry);	struct timespec now;	if (!__atime_needs_update(path, inode, false))		return;	if (!sb_start_write_trylock(inode->i_sb))		return;	if (__mnt_want_write(mnt) != 0)		goto skip_update;	/*	 * File systems can error out when updating inodes if they need to	 * allocate new space to modify an inode (such is the case for	 * Btrfs), but since we touch atime while walking down the path we	 * really don't care if we failed to update the atime of the file,	 * so just ignore the return value.	 * We may also fail on filesystems that have the ability to make parts	 * of the fs read only, e.g. subvolumes in Btrfs.	 */	now = current_time(inode);	update_time(inode, &now, S_ATIME);	__mnt_drop_write(mnt);skip_update:	sb_end_write(inode->i_sb);}EXPORT_SYMBOL(touch_atime);

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