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Lunev" Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Fiona Ebner Subject: Re: [PATCH] block: fix bdrv_next() skipping monitor-owned nodes Message-ID: References: <20260828222005.2888213-1-den@openvz.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260828222005.2888213-1-den@openvz.org> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 12 X-Spam_score: 1.2 X-Spam_bar: + X-Spam_report: (1.2 / 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, 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 29.08.2026 um 00:20 hat Denis V. Lunev geschrieben: > From: Denis V. Lunev > > it->bs is the cursor into monitor_bdrv_states for the second phase of > bdrv_next(), so it has to be NULL when that phase starts. Commit > f6d38c9f6d made the first phase store the node it returns there, to > unreference the right one when the graph changes underneath. The cursor > is now left pointing at the last BlockBackend root, so the second phase > resumes from there instead of from the head of the list and never > returns a node added before it. > > A skipped node drops out of the vm_stop and migration handover paths: > not flushed, not inactivated, not snapshotted. bdrv_inactivate_all() > still reports success, so the node keeps its image lock and the > migration target cannot open the image. Only detached nodes are hit in > practice, as these callers also recurse into children. > > Reset the cursor when the second phase starts. old_bs is taken at the > top of the function, so f6d38c9f6d keeps working. > > Fixes: f6d38c9f6d ("block-backend: fix edge case in bdrv_next() where BDS associated to BB changes") > Signed-off-by: Denis V. Lunev > Cc: Fiona Ebner > Cc: Kevin Wolf Thanks, applied to the block branch. Kevin