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Lunev" Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Hanna Reitz , Vladimir Sementsov-Ogievskiy , Andrey Drobyshev Subject: Re: [PATCH 13/13] iotests/298: cover the preallocation races Message-ID: References: <20260930165000.303236-1-den@openvz.org> <20260930165000.303236-14-den@openvz.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260930165000.303236-14-den@openvz.org> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 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: 5 X-Spam_score: 0.5 X-Spam_bar: / X-Spam_report: (0.5 / 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, 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-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS 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 Am 30.09.2026 um 18:49 hat Denis V. Lunev geschrieben: > From: Denis V. Lunev > > Three cases the filter has to get right, all deterministic: a write the > preallocation cannot reach goes through without waiting for it, a write > into the range it covers does not, and a write zeroes over data written > inside that range is not skipped as already zero. > > The second one cannot wait for the write to finish, because that is > what it is checking does not happen, and the data survives either way: > a preallocation that finds the write still in flight gives up. It asks > whether the write got past the filter at all instead, by leaving a > breakpoint below it. > > Signed-off-by: Denis V. Lunev > CC: Kevin Wolf > CC: Hanna Reitz > CC: Vladimir Sementsov-Ogievskiy > CC: Andrey Drobyshev What does launching the requests in different iothreads contribute here? If it's completely deterministic and every request is suspended when another one is active, shouldn't a single-threaded test trigger the same cases? I'm not asking you to change the test code, but I'd like to have the commit message tell what difference the iothreads make here. Kevin