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Mon, 6 Oct 2025 14:46:11 +0000 (UTC) Received: from localhost (unknown [10.2.16.162]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 236A6180035E; Mon, 6 Oct 2025 14:46:10 +0000 (UTC) Date: Mon, 6 Oct 2025 10:46:09 -0400 From: Stefan Hajnoczi To: Vladimir Sementsov-Ogievskiy Cc: qemu-devel@nongnu.org, Kevin Wolf , qemu-block@nongnu.org, Jean-Louis Dupond , Hanna Reitz Subject: Re: [PATCH 1/3] file-posix: populate pwrite_zeroes_alignment Message-ID: <20251006144609.GA21887@fedora> References: <20251002184000.410486-1-stefanha@redhat.com> <20251002184000.410486-2-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="IncuC9+/ajPiGfdx" Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.441, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org --IncuC9+/ajPiGfdx Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Oct 03, 2025 at 11:04:38AM +0300, Vladimir Sementsov-Ogievskiy wrot= e: > On 02.10.25 21:39, Stefan Hajnoczi wrote: > > Linux block devices require write zeroes alignment whereas files do not. > >=20 > > It may come as a surprise that block devices opened in buffered I/O mode > > require the alignment although regular read/write requests do not. > >=20 > > Therefore it is necessary to populate the pwrite_zeroes_alignment field. > >=20 > > Signed-off-by: Stefan Hajnoczi > > --- > > block/file-posix.c | 17 +++++++++++++++++ > > 1 file changed, 17 insertions(+) > >=20 > > diff --git a/block/file-posix.c b/block/file-posix.c > > index 8c738674ce..05c92c824d 100644 > > --- a/block/file-posix.c > > +++ b/block/file-posix.c > > @@ -1602,6 +1602,23 @@ static void raw_refresh_limits(BlockDriverState = *bs, Error **errp) > > bs->bl.pdiscard_alignment =3D dalign; > > } > > + > > +#ifdef __linux__ > > + /* > > + * When request_alignment > 1, pwrite_zeroes_alignment does no= t need to > > + * be set explicitly. When request_alignment =3D=3D 1, it must= be set > > + * explicitly because Linux requires logical block size alignm= ent. > > + */ > > + if (bs->bl.request_alignment =3D=3D 1) { >=20 > would "if (!s->needs_alignment) {" be a more visual check? This way reade= r will not have to analyze > raw_probe_alignment, and understand that needs_alignment=3Dfalse is the o= nly path for block device > to have request_alignment=3D=3D1. Yes, that would make it easier to understand. Thanks! >=20 > > + ret =3D probe_logical_blocksize(s->fd, > > + &bs->bl.pwrite_zeroes_alignm= ent); > > + if (ret < 0) { > > + error_setg_errno(errp, -ret, > > + "Failed to probe logical block size"); > > + return; > > + } > > + } > > +#endif /* __linux__ */ > > } > > raw_refresh_zoned_limits(bs, &st, errp); >=20 >=20 > --=20 > Best regards, > Vladimir >=20 --IncuC9+/ajPiGfdx Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQEzBAEBCgAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmjj1jEACgkQnKSrs4Gr c8jfzwf+JKiNm2E4ST0w0yltOxrV2na5rwX5eLATyYmfqB7iSX0WJJgDIN4Q22Qk hbkirOuuVj15uBjZNdgI8zKCDpX2/MD2SGbB5Nu8FMcANJqIn6eENirpDrnhf7FQ py7s6YGPyfNedKAo2OEFamfm6NhpSlYKX6mMgW0w8U7b7riRcoTh/CT71k+D/DUm 0bB0yYsW6Cdj1DFn4P9AvBtzmm1XVP7uoL10wuHZsf58f+FQ4zw8Z8u1JzkwM87W i/KHGa/uUfGOnvWdP5lR0bJtFwiHnk+j3QuDKpiLuU48sURCjqWJVQTfd3XDT2BP mhl7TH9bmqeASK3Rf0QHE4cVT3AIDQ== =P0De -----END PGP SIGNATURE----- --IncuC9+/ajPiGfdx--