From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Nicholas A. Bellinger" Subject: Re: [PATCH] [ConfigFS]: Allow symbolic links from a SysFS struct kobject source. Date: Fri, 17 Oct 2008 19:41:56 -0700 Message-ID: <1224297716.5556.365.camel@haakon2.linux-iscsi.org> References: <1224226555.5556.279.camel@haakon2.linux-iscsi.org> <20081017074453.GA4850@kroah.com> <1224231739.5556.303.camel@haakon2.linux-iscsi.org> <20081017173959.GC2221@kroah.com> <1224271173.5556.349.camel@haakon2.linux-iscsi.org> <20081017201017.GA10613@kroah.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Joel Becker , LKML , Linux-fsdevel , linux-scsi , "Linux-iSCSI.org Target Dev" , SCST-Devel , Alan Stern , Andrew Morton , Christoph Hellwig To: Greg KH Return-path: Received: from smtp128.sbc.mail.sp1.yahoo.com ([69.147.65.187]:34610 "HELO smtp128.sbc.mail.sp1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751680AbYJRCnK (ORCPT ); Fri, 17 Oct 2008 22:43:10 -0400 In-Reply-To: <20081017201017.GA10613@kroah.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Fri, 2008-10-17 at 13:10 -0700, Greg KH wrote: > On Fri, Oct 17, 2008 at 12:19:33PM -0700, Nicholas A. Bellinger wrote: > > On Fri, 2008-10-17 at 10:39 -0700, Greg KH wrote: > > > On Fri, Oct 17, 2008 at 01:22:18AM -0700, Nicholas A. Bellinger wrote: > > > > On Fri, 2008-10-17 at 00:44 -0700, Greg KH wrote: > > > > > On Thu, Oct 16, 2008 at 11:55:55PM -0700, Nicholas A. Bellinger wrote: > > > > > > Hi Joel, Greg and Co, > > > > > > > > > > > > Here is the the first working code for allowing configfs to handle > > > > > > symlinks from sysfs struct kobject based code. Here is the commit: > > > > > > passing struct kobject into generic target_core_mod subsystem plugins > > > > > > for locating struct block_device and struct scsi_device.. > > > > > > > > > > Um, no. > > > > > > > > > > You are trying to create symlinks dynamically across superblocks and > > > > > mount points? As one of your #warning states, this isn't possible to do > > > > > correctly, nor is it even a good idea. > > > > > > > > > > So I'd have to reject this patch, sorry. > > > > > > > > > > What is the problem you are attempting to solve here? > > > > > > > > > > > > > So, the generic target_core_mod engine that lives > > > > under /sys/kernel/config/target/core needs a method to locate struct > > > > block_device and struct scsi_device for access via bio_submit() and > > > > scsi_execute_() respectively. > > > > > > Then just pass the "name" of the block device into a configfs file, > > > nothing more is needed, right? > > > > > > > What are the preferred methods for accessing struct block_device and > > struct scsi_device from "name"..? > > call "find_by_name" for a type (this would be block type) and get the > return value? Can't remember the actual function call, but it's obvious > if you look at device.h. > Got it, thanks.. > > > > Originally, target_core_mod used key echoed through configfs attributes > > > > like so: > > > > > > > > export TARGET=/sys/kernel/config/target/core/ > > > > > > > > # Create $STORAGE_OBJECT of type Linux/BLOCK in generic target_core_mod > > > > mkdir -p $TARGET/iblock_0/lvm_test0 > > > > # OLD METHOD to reference struct block_device > > > > echo iblock_major=254,iblock_minor=2 > $TARGET/iblock_0/lvm_test0/control > > > > echo 1 > $TARGET/iblock_0/lvm_test0/enable > > > > # NEW METHOD using sysfs ->configfs symlinks to reference struct block_device > > > > ln -s /sys/block/dm-2 $TARGET/iblock_0/lvm_test0/dm-2 > > > > > > No, you can't do a symlink across superblocks and expect it to work like > > > you are thinking internally. > > > > > > > As I am coding configfs_follow_symlink() to work with sysfs > > source symlinks I am starting to see that.. :-) I am still going to > > hack on it for a bit and see if I can get it running so that it works.. > > Even if you get it "to work", it's not going to be able to be accepted, > sorry. > not a problem, it was just something that I wanted to see if it was even possible. I will refocus on using the method to locate what Linux storage objects can be used for target_core_mod that Joel mentioned and your recommendations. Thanks, --nab