Re: [PATCH 1/2] common/rc: add functions to check or write objects under /sys/fs

[Zorro Lang <zlang@redhat.com>]

On Fri, May 27, 2016 at 01:27:56PM -0500, Eric Sandeen wrote:
> On 5/27/16 1:05 PM, Eric Sandeen wrote:
> 
> > So maybe something like this (not tested)
> > 
> > + /* Test for the existence of a sysfs entry at /sys/fs/$FSTYP/$DEV/$ENTRY */
> > +_require_fs_sys_fs()
> > +{
> > +        local dev=$1
> > +        local target=$2
> > +        local dname=""
> > +        local tmp_mnt=`mktemp -d`
> > +
> > +        if [ ! -b "$dev" -o -z "$target" ];then
> > +	        echo "Usage: _require_fs_sys_fs <device> <sysfs_path>"
> > +                exit 1
> > +        fi
> > +
> > +        dname=$(basename $(readlink -f $dev))
> > +        _mount -t $FSTYP `_common_dev_mount_options` $dev $tmp_mnt
> > +        if [ ! -e /sys/fs/${FSTYP}/${dname}/$target ];then
> > +                umount $tmp_mnt
> > +                rm -f $tmp_mnt
> > +                _notrun "/sys/fs/${FSTYP}/${dname}/$target: No such file or directory"
> > +        fi
> > +        umount $SCRATCH_MNT
> > +        rm -f $tmp_mnt
> > +}
> > 
> > and it would work for either SCRATCH or TEST?
> 
> I guess nothing guarantees that the device is already mkfs'd, at least
> for scratch, so maybe it also needs to catch a mount failure,
> with a message about "could not mount; mkfs first in your test?"
> or something like that.

Yes, if we don't mkfs in _require_fs_sys_fs(), that means we need the
caller make sure they do that. I will check the mount error likes:

_mount -t $FSTYP `_common_dev_mount_options` $dev $tmp_mnt
if [ $? -ne 0 ];then
	rm -f $tmp_mnt
	_notrun "could not mount; mkfs first in your test?"
elif [ ! -e /sys/fs/${FSTYP}/${dname}/$target ];then
	....
fi

Thanks,
Zorro

> 
> -Eric
> --
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