Re: [PATCH] sysfs: Optionally count subdirectories to support buggyapplications

From: Greg Kroah-Hartman
Date: Wed Feb 01 2012 - 17:25:22 EST


On Wed, Feb 01, 2012 at 02:21:59PM -0800, Eric W. Biederman wrote:
>
> lm_sensors and possibly other applications get confused if all sysfs
> directories return nlink == 1. The lm_sensors code that got confused
> was just wrong and a fixed version of lm_sensors should be released
> shortly.
>
> There may be other applications that have problems with sysfs return
> nlink == 1 for directories. To allow people to continue to use old
> versions of userspace with new kernels add to sysfs a compile time
> option to maintain mostly precise directory counts for those people who
> don't mind the cost.
>
> I have moved where we keep nlink in sysfs_dirent as compared to previous
> versions of subdirectory counting to a location that packs better.
>
> Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> ---
> fs/sysfs/Kconfig | 15 +++++++++++++++
> fs/sysfs/dir.c | 8 ++++++++
> fs/sysfs/inode.c | 2 ++
> fs/sysfs/sysfs.h | 38 ++++++++++++++++++++++++++++++++++++++
> 4 files changed, 63 insertions(+), 0 deletions(-)
>
> diff --git a/fs/sysfs/Kconfig b/fs/sysfs/Kconfig
> index 8c41fea..9b403e9 100644
> --- a/fs/sysfs/Kconfig
> +++ b/fs/sysfs/Kconfig
> @@ -21,3 +21,18 @@ config SYSFS
> example, "root=03:01" for /dev/hda1.
>
> Designers of embedded systems may wish to say N here to conserve space.
> +
> +config SYSFS_COUNT_LINKS
> + bool "sysfs count subdirectoires to support buggy applications"
> + default n

As we don't want to break things, this should be default y, right?

Also, should we list this in the feature_removal list as well so that we
can get rid of it in a year or so?

thanks,

greg k-h
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