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Lunev" Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Hanna Reitz , Vladimir Sementsov-Ogievskiy , Andrey Drobyshev Subject: Re: [PATCH 10/13] qemu-io: add -g to write past the end of the image Message-ID: References: <20260930165000.303236-1-den@openvz.org> <20260930165000.303236-11-den@openvz.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260930165000.303236-11-den@openvz.org> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 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: 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_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-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org X-Spam-Status: No, score=-15.8 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 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 > > The preallocate filter only does anything for a write that lands beyond > the end of its file, and that is what a format driver above it produces. > qemu-io could not produce it at all: the backend rejects such a request > with EIO, and the write path asserts without the resize permission, so > the filter could only be reached by stacking a real format on top and > letting it choose the offsets. > > Take the resize permission and allow writes beyond the end when -g is > given, which leaves the tool free to address the filter directly. > > Signed-off-by: Denis V. Lunev > CC: Kevin Wolf > CC: Hanna Reitz > CC: Vladimir Sementsov-Ogievskiy > CC: Andrey Drobyshev > @@ -310,6 +330,8 @@ static void usage(const char *name) > " specify tracing options\n" > " see qemu-img(1) man page for full description\n" > " -U, --force-share force shared permissions\n" > +" -g, --grow let writes extend the image past its end,\n" > +" as a format driver does to its file\n" > " -h, --help display this help and exit\n" > " -V, --version output version information and exit\n" > "\n" > @@ -503,7 +525,7 @@ static QemuOptsList file_opts = { > int main(int argc, char **argv) > { > int readonly = 0; > - const char *sopt = "hVc:d:f:rsnCmki:t:T:U"; > + const char *sopt = "hVc:d:f:grsnCmki:t:T:U"; > const struct option lopt[] = { > { "help", no_argument, NULL, 'h' }, > { "version", no_argument, NULL, 'V' }, > @@ -522,6 +544,7 @@ int main(int argc, char **argv) > { "object", required_argument, NULL, OPTION_OBJECT }, > { "image-opts", no_argument, NULL, OPTION_IMAGE_OPTS }, > { "force-share", no_argument, 0, 'U'}, > + { "grow", no_argument, NULL, 'g' }, > { NULL, 0, NULL, 0 } > }; --growable instead of just --grow would be more consistent with the terminology we use elsewhere (e.g. block export interfaces). Kevin