linux-kernel - Re: [PATCH 04/13] sysfs: Simplify sysfs_chmod

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Date:	Tue, 3 Nov 2009 20:43:32 -0600
From:	"Serge E. Hallyn" <serue@...ibm.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Greg Kroah-Hartman <gregkh@...e.de>,
	Kay Sievers <kay.sievers@...y.org>, Greg KH <greg@...ah.com>,
	linux-kernel@...r.kernel.org, Tejun Heo <tj@...nel.org>,
	Cornelia Huck <cornelia.huck@...ibm.com>,
	linux-fsdevel@...r.kernel.org,
	Eric Dumazet <eric.dumazet@...il.com>,
	Benjamin LaHaise <bcrl@...et.ca>,
	"Eric W. Biederman" <ebiederm@...stanetworks.com>
Subject: Re: [PATCH 04/13] sysfs: Simplify sysfs_chmod_file semantics

Quoting Eric W. Biederman (ebiederm@...ssion.com):
> From: Eric W. Biederman <ebiederm@...ssion.com>
> 
> Currently every caller of sysfs_chmod_file happens at either
> file creation time to set a non-default mode or in response
> to a specific user requested space change in policy.  Making
> timestamps of when the chmod happens and notification of
> a file changing mode uninteresting.

But these changes can occur by togging values in sysfs files
(i.e. f71805f.c), right?  Is this (specifically not doing inotify)
definately uncontroversial?

I can't exactly picture an admin sitting there watching
nautilus for a sysfs file to become writeable, but could
imagine some site's automation getting hung...  Or am I way
off base?

> Remove the unnecessary time stamp and filesystem change
> notification, and removes the last of the explicit inotify
> and donitfy support from sysfs.
> 
> Acked-by: Tejun Heo <tj@...nel.org>
> Signed-off-by: Eric W. Biederman <ebiederm@...stanetworks.com>
> ---
>  fs/sysfs/file.c |   10 +---------
>  1 files changed, 1 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
> index f5ea468..faa1a80 100644
> --- a/fs/sysfs/file.c
> +++ b/fs/sysfs/file.c
> @@ -604,17 +604,9 @@ int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
>  	mutex_lock(&inode->i_mutex);
> 
>  	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
> -	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
> -	newattrs.ia_ctime = current_fs_time(inode->i_sb);
> +	newattrs.ia_valid = ATTR_MODE;
>  	rc = sysfs_setattr(victim, &newattrs);
> 
> -	if (rc == 0) {
> -		fsnotify_change(victim, newattrs.ia_valid);
> -		mutex_lock(&sysfs_mutex);
> -		victim_sd->s_mode = newattrs.ia_mode;
> -		mutex_unlock(&sysfs_mutex);
> -	}
> -
>  	mutex_unlock(&inode->i_mutex);
>   out:
>  	dput(victim);
> -- 
> 1.6.5.2.143.g8cc62
> 
> --
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