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Lunev" Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Andrey Drobyshev , Hanna Reitz , qemu-stable@nongnu.org Subject: Re: [PATCH v4 2/5] block: reject a reopen of an unusable node instead of crashing Message-ID: References: <20260824133729.1141990-1-den@openvz.org> <20260824133729.1141990-3-den@openvz.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260824133729.1141990-3-den@openvz.org> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 10 X-Spam_score: 1.0 X-Spam_bar: + X-Spam_report: (1.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.24, 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_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no 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-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 Am 24.08.2026 um 15:37 hat Denis V. Lunev geschrieben: > From: Denis V. Lunev > > qcow2_signal_corruption() drops bs->drv, so a node can lose its driver > at any time and a reopen has to expect that. Both ends of the path > assume otherwise: > > $ qemu-io -c "read 0 64k" -c "reopen -r" corrupt.qcow2 > qcow2: Marking image as corrupt: Cluster allocation offset 0x1200 > unaligned (L2 offset: 0x40000, L2 index: 0); ... > Segmentation fault > > bdrv_reopen_queue_child() dereferences bs->drv while descending into > the children the node opened itself, and bdrv_reopen_prepare() asserts > on it. commit_clean() reopens the base of a commit job back to > read-only, so a base which goes corrupt under the job arrives here too. > > There is nothing to reopen for such a node, so stop descending into its > children and let bdrv_reopen_prepare() report what every caller of > bdrv_reopen() already handles. bdrv_reopen_commit() and > bdrv_reopen_abort() keep their assertion, only a prepared entry reaches > them. > > Signed-off-by: Denis V. Lunev > Reviewed-by: Andrey Drobyshev > CC: Kevin Wolf > CC: Hanna Reitz > CC: Andrey Drobyshev > Cc: qemu-stable@nongnu.org Reviewed-by: Kevin Wolf