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Tsirkin" , virtio-fs@redhat.com, qemu-block@nongnu.org, Stefan Hajnoczi , Peter Maydell , Fam Zheng , "Dr. David Alan Gilbert" , Fiona Ebner , qemu-stable@nongnu.org, Eric Blake Subject: [PULL 3/6] block: fix detect-zeroes= with BDRV_REQ_REGISTERED_BUF Date: Thu, 9 Feb 2023 10:25:17 -0500 Message-Id: <20230209152520.434183-4-stefanha@redhat.com> In-Reply-To: <20230209152520.434183-1-stefanha@redhat.com> References: <20230209152520.434183-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H2=-0.001, SPF_HELO_NONE=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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1675956381162100003 Content-Type: text/plain; charset="utf-8" When a write request is converted into a write zeroes request by the detect-zeroes=3D feature, it is no longer associated with an I/O buffer. The BDRV_REQ_REGISTERED_BUF flag doesn't make sense without an I/O buffer and must be cleared because bdrv_co_do_pwrite_zeroes() fails with -EINVAL when it's set. Fiona Ebner bisected and diagnosed this QEMU 7.2 regression where writes containing zeroes to a blockdev with discard=3Dunmap,detect-zeroes=3Dunmap fail. Buglink: https://gitlab.com/qemu-project/qemu/-/issues/1404 Fixes: e8b6535533be ("block: add BDRV_REQ_REGISTERED_BUF request flag") Tested-by: Fiona Ebner Cc: qemu-stable@nongnu.org Reviewed-by: Eric Blake Reviewed-by: Hanna Czenczek Signed-off-by: Stefan Hajnoczi Message-Id: <20230207203719.242926-2-stefanha@redhat.com> --- block/io.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/block/io.c b/block/io.c index 2dc0c13e41..d2be37b11e 100644 --- a/block/io.c +++ b/block/io.c @@ -1926,6 +1926,9 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChil= d *child, if (bs->detect_zeroes =3D=3D BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP)= { flags |=3D BDRV_REQ_MAY_UNMAP; } + + /* Can't use optimization hint with bufferless zero write */ + flags &=3D ~BDRV_REQ_REGISTERED_BUF; } =20 if (ret < 0) { --=20 2.39.1