From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42268) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bBqh6-0002o8-CF for qemu-devel@nongnu.org; Sat, 11 Jun 2016 17:43:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bBqh5-0001aw-96 for qemu-devel@nongnu.org; Sat, 11 Jun 2016 17:43:52 -0400 References: <1464973388-15821-1-git-send-email-eblake@redhat.com> <1464973388-15821-3-git-send-email-eblake@redhat.com> <20160607121234.GF4684@noname.str.redhat.com> From: Eric Blake Message-ID: <575C860C.6010906@redhat.com> Date: Sat, 11 Jun 2016 15:43:40 -0600 MIME-Version: 1.0 In-Reply-To: <20160607121234.GF4684@noname.str.redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="In7O7D1OtGhHCRd9EiHVNHkLW9xdKCJXd" Subject: Re: [Qemu-devel] [PATCH 2/5] block: Honor flags during bdrv_aligned_preadv() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: qemu-devel@nongnu.org, mreitz@redhat.com, qemu-block@nongnu.org, Stefan Hajnoczi , Fam Zheng This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --In7O7D1OtGhHCRd9EiHVNHkLW9xdKCJXd Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 06/07/2016 06:12 AM, Kevin Wolf wrote: > Am 03.06.2016 um 19:03 hat Eric Blake geschrieben: >> Not that we pass any flags during reads yet, but we may want to >> support BDRV_REQ_FUA on reads in the future. So don't throw >> away the input flags. >> >> Signed-off-by: Eric Blake >=20 > Do we want to pass flags to bdrv_co_do_copy_on_readv(), too? I guess we= > would use them for the preadv call there, but continue to use 0 as the > pwritev flags. What about BDRV_REQ_MAY_UNMAP if bdrv_co_do_copy_on_readv() detects a block of zeroes? This just got a lot trickier, so I think my short-term solution is to just assert(!flags) and add a comment that whoever implements flags on read has to solve the issue at that time, so that I'm not stalling the rest of this series on thinking about things that don't matter yet. >=20 > We may also want to introduce a .supported_read_flags, but perhaps this= > is not something to do in this patch. Yeah, I think we'll want that, at the point where we start worrying about read flags. > And we don't even use > .supported_write_flags for drivers that have a native .bdrv_co_pwritev.= > Of course, that's even less related to this patch. I guess I should sen= d > a fix for that. Thanks. --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --In7O7D1OtGhHCRd9EiHVNHkLW9xdKCJXd Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJXXIYMAAoJEKeha0olJ0NqImoH/i82F4JiQWTcnw+vNIAC0KIQ ITYL0wdAt9JY0wCFLZOanyFkJNQaOagrOraZFU/CzIt8YjuKyJSm314ME+9b2lhU 7kWZBPpLgsOATZbSGj1BIRrUT+VLYxgfU4/V30FVxJwt5VcmUJkd16ArUwVvKidT kSNzqGPSbbHUWpa8WCFSUaHaLZO1aRK+bIZsAmnoWqk0sZZznelyoClhtjZZCmaw Qn9rNtTI726dItYFUTKOUDnCiImR6AenP/lKkdwaUG0VGP1+4Bj2GbN0xgcVrlNB oXu0X/4HkUs3YYGcSNuDNHoCJuz1kvTtwAnlRKd9CYKtQ3dakjwxOonLo+ozkck= =RTRS -----END PGP SIGNATURE----- --In7O7D1OtGhHCRd9EiHVNHkLW9xdKCJXd--