From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zdenek Kabelac Subject: Re: Not able to create a device mapper target node Date: Tue, 25 Jun 2013 10:19:24 +0200 Message-ID: <51C9528C.6010700@redhat.com> References: Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development Cc: monica g List-Id: dm-devel.ids Dne 24.6.2013 09:19, monica g napsal(a): > Hi, > > I wrote a basic device mapper driver which caches reads. > > I gave dm msg prefix as below > #define DM_MSG_PREFIX "cacheread". > > When i try to create a device mapper node using the below command > echo "0 `blockdev --getsize /dev/sda2` cacheread /dev/sda2 0" | dmsetup create > cacheread > > the system hangs.I am not getting any error messages. Why not looking into a basic linear driver - linux/drivers/md/dm-stripe.c and start updating this driver for your needs. Kernel device driver development is not easily debugable from userspace. Also you might be interested to look at dm-cache driver available from 3.9 kernel and which does much more advanced caching of reads as well as writes.... Regards Zdenek > > When i try to create a device mapper node for linear target(this target is > already present with the device mapper code) using below command > > echo "0 `blockdev --getsize /dev/sda2` linear /dev/sda2 0" | dmsetup create linear > it succeeds and creates device node linear in /dev/mapper directory. > > I am stuck with this issue and not able to proceed furthur. > > Please let me know if you have any suggestions. > > Any help is truely appreciated. > > Thanks in advance. > > Regards, > Monica > > > > > -- > dm-devel mailing list > dm-devel@redhat.com > https://www.redhat.com/mailman/listinfo/dm-devel >