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Lunev" Cc: "Denis V. Lunev" , qemu-devel@nongnu.org, qemu-block@nongnu.org, Kevin Wolf , Hanna Reitz , Paolo Bonzini , Fam Zheng Subject: Re: [PATCH 0/4] block, scsi-disk: honour a size change on child replacement Message-ID: References: <20260812121500.1034178-1-den@openvz.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20260616 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.129.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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_LOW=-0.7, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Fri, Oct 30, 2026 at 12:08:24PM +0100, Denis V. Lunev wrote: > On 8/12/26 14:14, Denis V. Lunev wrote: > > qom-set of the 'drive' property is allowed on a realized device and ends > > up in bdrv_replace_child_bs(), which swaps the node a BdrvChild points to > > without telling the parent anything about it. Every other way the size of > > a node changes goes through bdrv_co_truncate(), which does notify, so a > > device model caching the size of its child has no way to learn that it > > changed. > > > > scsi-disk is the one really hurt by this. check_lba_range() validates > > every guest request against SCSIDevice.max_lba, filled in by > > scsi_disk_reset() and updated only by the READ CAPACITY(10) and (16) > > handlers. Point a scsi-hd at a larger node and every request past the end > > of the old one is refused with ILLEGAL REQUEST / LOGICAL BLOCK ADDRESS > > OUT OF RANGE for the whole life of the device, which Linux turns into > > EREMOTEIO for reads as well as writes. It is silent on the host: > > out-of-range requests are answered by scsi_check_condition() and never > > reach scsi_handle_rw_error(), so there is no BLOCK_IO_ERROR event and > > io-status stays 'ok'. virtio-blk and ide call blk_get_geometry() for > > every request, so they end up with a stale idea of the size but never > > refuse I/O the node underneath can serve. > > > > Signed-off-by: Denis V. Lunev > > Cc: Kevin Wolf > > Cc: Hanna Reitz > > Cc: Paolo Bonzini > > Cc: Fam Zheng > > > > Denis V. Lunev (4): > > block: notify the parent when a replaced child has a different size > > scsi-disk: refresh the cached capacity from the resize callback > > tests/qtest/virtio-scsi: cover a replacement that changes the size > > tests/qemu-iotests/qom-set-drive: replace with a differently sized > > node > > > > block.c | 13 +++++ > > hw/scsi/scsi-disk.c | 16 ++++-- > > include/block/block_int-io.h | 3 ++ > > tests/qemu-iotests/tests/qom-set-drive | 14 +++-- > > tests/qemu-iotests/tests/qom-set-drive.out | 2 + > > tests/qtest/virtio-scsi-test.c | 63 ++++++++++++++++++++++ > > 6 files changed, 104 insertions(+), 7 deletions(-) > > > > > > base-commit: 3e3ccab106f879b1512f8e0d51a827dd4de30e22 > ping Looks like this one has sat for a while; while it is not directly related to my usual NBD pulls, I'm in the middle of preparing a block layer pull request today so I'll add this one in my queue if it passes my testing. -- Eric Blake, Principal Software Engineer Red Hat, Inc. 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