linux-kernel - Re: sysfs_chmod_file() broken in 2.6.33-rc4-git6

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Date:	Wed, 20 Jan 2010 16:00:08 +0100
From:	Jean Delvare <khali@...ux-fr.org>
To:	ebiederm@...ssion.com (Eric W. Biederman)
Cc:	Greg Kroah-Hartman <gregkh@...e.de>,
	LKML <linux-kernel@...r.kernel.org>, Tejun Heo <tj@...nel.org>,
	Serge Hallyn <serue@...ibm.com>
Subject: Re: sysfs_chmod_file() broken in 2.6.33-rc4-git6

On Wed, 20 Jan 2010 06:01:02 -0800, Eric W. Biederman wrote:
> Jean Delvare <khali@...ux-fr.org> writes:
> 
> > Hi Eric, Greg,
> >
> > While working on a driver using 2.6.33-rc4-git6 as my environment, I
> > have found that sysfs_chmod_file() called from a kernel driver no
> > longer works. It doesn't return any error nor print any message in the
> > logs, it simply has no effect. The same code worked fine using kernel
> > 2.6.32. I have bisected it down to the following commit:
> >
> > commit e61ab4ae48fbf477f5b9fcbec9e1b8dc789920d0
> > Author: Eric W. Biederman <ebiederm@...ssion.com>
> > Date:   Fri Nov 20 16:08:53 2009 -0800
> >
> >     sysfs: Implement sysfs_getattr & sysfs_permission
> >     
> >     With the implementation of sysfs_getattr and sysfs_permission
> >     sysfs becomes able to lazily propogate inode attribute changes
> >     from the sysfs_dirents to the vfs inodes.   This paves the way
> >     for deleting significant chunks of now unnecessary code.
> >     
> >     While doing this we did not reference sysfs_setattr from
> >     sysfs_symlink_inode_operations so I added along with
> >     sysfs_getattr and sysfs_permission.
> >     
> >     Acked-by: Tejun Heo <tj@...nel.org>
> >     Acked-by: Serge Hallyn <serue@...ibm.com>
> >     Signed-off-by: Eric W. Biederman <ebiederm@...stanetworks.com>
> >     Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
> >
> > Eric, can you please look at your code again and see if you can find
> > any obvious issue?
> 
> Does this fix your issue?
> 
> Eric
> 
> 
> diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
> index 220b758..6a06a1d 100644
> --- a/fs/sysfs/inode.c
> +++ b/fs/sysfs/inode.c
> @@ -81,24 +81,23 @@ int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr * iattr)
>  		if (!sd_attrs)
>  			return -ENOMEM;
>  		sd->s_iattr = sd_attrs;
> -	} else {
> -		/* attributes were changed at least once in past */
> -		iattrs = &sd_attrs->ia_iattr;
> -
> -		if (ia_valid & ATTR_UID)
> -			iattrs->ia_uid = iattr->ia_uid;
> -		if (ia_valid & ATTR_GID)
> -			iattrs->ia_gid = iattr->ia_gid;
> -		if (ia_valid & ATTR_ATIME)
> -			iattrs->ia_atime = iattr->ia_atime;
> -		if (ia_valid & ATTR_MTIME)
> -			iattrs->ia_mtime = iattr->ia_mtime;
> -		if (ia_valid & ATTR_CTIME)
> -			iattrs->ia_ctime = iattr->ia_ctime;
> -		if (ia_valid & ATTR_MODE) {
> -			umode_t mode = iattr->ia_mode;
> -			iattrs->ia_mode = sd->s_mode = mode;
> -		}
> +	}
> +	/* attributes were changed at least once in past */
> +	iattrs = &sd_attrs->ia_iattr;
> +
> +	if (ia_valid & ATTR_UID)
> +		iattrs->ia_uid = iattr->ia_uid;
> +	if (ia_valid & ATTR_GID)
> +		iattrs->ia_gid = iattr->ia_gid;
> +	if (ia_valid & ATTR_ATIME)
> +		iattrs->ia_atime = iattr->ia_atime;
> +	if (ia_valid & ATTR_MTIME)
> +		iattrs->ia_mtime = iattr->ia_mtime;
> +	if (ia_valid & ATTR_CTIME)
> +		iattrs->ia_ctime = iattr->ia_ctime;
> +	if (ia_valid & ATTR_MODE) {
> +		umode_t mode = iattr->ia_mode;
> +		iattrs->ia_mode = sd->s_mode = mode;
>  	}
>  	return 0;
>  }

Yes, this fixes my problem. Thanks for the fast fix!

-- 
Jean Delvare
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