From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38618) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uwvi0-0004Cc-Gw for qemu-devel@nongnu.org; Wed, 10 Jul 2013 10:49:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Uwvhu-0000Sm-I0 for qemu-devel@nongnu.org; Wed, 10 Jul 2013 10:49:32 -0400 Received: from mx.ipv6.kamp.de ([2a02:248:0:51::16]:51381 helo=mx01.kamp.de) by eggs.gnu.org with smtp (Exim 4.71) (envelope-from ) id 1Uwvhu-0000Sb-6x for qemu-devel@nongnu.org; Wed, 10 Jul 2013 10:49:26 -0400 Message-ID: <51DD7472.9020303@kamp.de> Date: Wed, 10 Jul 2013 16:49:22 +0200 From: Peter Lieven MIME-Version: 1.0 References: <1372338695-411-1-git-send-email-pl@kamp.de> <1372338695-411-11-git-send-email-pl@kamp.de> <20130710113313.GK3898@dhcp-200-207.str.redhat.com> <51DD69F8.3050305@kamp.de> <20130710142807.GQ3898@dhcp-200-207.str.redhat.com> In-Reply-To: <20130710142807.GQ3898@dhcp-200-207.str.redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCHv2 10/11] iscsi: ignore aio_discard if unsupported List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: pbonzini@redhat.com, ronniesahlberg@gmail.com, qemu-devel@nongnu.org, stefanha@redhat.com Am 10.07.2013 16:28, schrieb Kevin Wolf: > Am 10.07.2013 um 16:04 hat Peter Lieven geschrieben: >> Am 10.07.2013 13:33, schrieb Kevin Wolf: >>> Am 27.06.2013 um 15:11 hat Peter Lieven geschrieben: >>>> if the target does not support UNMAP or the request >>>> is too big silently ignore the discard request. >>>> >>>> Signed-off-by: Peter Lieven >>> Why not loop for the "too big" case? You can probably use the same logic >>> for unmapping the whole device in .bdrv_create and here. >> right, but looping in an aio function seemed not so trivial to me. >> it seems more and more obvious to me that the best would be to change >> all the remaining aio routines to co routines. > The pattern for AIO functions is that the real work of submitting > requests is done in the AIO callback, and it submits new AIO requests > calling back into the same callback as long as acb->remaining_secs > 0 > (or something like that). > > You can still see that kind of thing alive in qed_aio_next_io(), (most > of?) the rest is converted to coroutines because it makes the code look > nicer. would you agree if I leave the easy version in just to fix the potential problems if iscsi_aio_discard is called with too high nb_sectors or on a storage where UNMAP is unsupported. I will add a TODO with the comment that the limit of iscsi->max_unmap should be replaced by a loop once the routine is replaced by a coroutine? > >> in this case i could add the too big logic in iscsi_co_discard and simply call >> it from iscsi_co_write_zeroes. > I think that would be the nicest solution. I promised to take care of this for 1.7.0 latest. Peter