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Thu, 26 Mar 2026 02:21:01 -0700 (PDT) From: Silvan Kaiser To: qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, kwolf@redhat.com, hreitz@redhat.com, pierrick.bouvier@linaro.org, eblake@redhat.com, armbru@redhat.com, Silvan Kaiser Subject: [PATCH 2/3] docs/system: Document locking=posix option for file block driver Date: Thu, 26 Mar 2026 10:19:47 +0100 Message-ID: <20260326091948.194529-3-silvan@quobyte.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260326091948.194529-1-silvan@quobyte.com> References: <20260326091948.194529-1-silvan@quobyte.com> MIME-Version: 1.0 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2a00:1450:4864:20::32c; envelope-from=silvan@quobyte.com; helo=mail-wm1-x32c.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @quobyte.com) X-ZM-MESSAGEID: 1774516907050154100 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Signed-off-by: Silvan Kaiser --- docs/system/qemu-block-drivers.rst.inc | 3 +++ qemu-options.hx | 10 ++++++---- 2 files changed, 9 insertions(+), 4 deletions(-) diff --git a/docs/system/qemu-block-drivers.rst.inc b/docs/system/qemu-bloc= k-drivers.rst.inc index 384e95ba76..bdecbf39ca 100644 --- a/docs/system/qemu-block-drivers.rst.inc +++ b/docs/system/qemu-block-drivers.rst.inc @@ -882,6 +882,9 @@ the POSIX locking API will be used. In this case there = is a risk that the lock will get silently lost when doing hot plugging and block jobs, due to the shortcomings of the POSIX locking API. =20 +To force the use of POSIX locks even when OFD locking is available, specify +"locking=3Dposix". The same caveats about silent lock loss apply. + QEMU transparently handles lock handover during shared storage migration. = For shared virtual disk images between multiple VMs, the "share-rw" device opt= ion should be used. diff --git a/qemu-options.hx b/qemu-options.hx index 21972f8326..23502c5aa6 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -1540,10 +1540,12 @@ SRST default: threads) =20 ``locking`` - Specifies whether the image file is protected with Linux OFD - / POSIX locks. The default is to use the Linux Open File - Descriptor API if available, otherwise no lock is applied. - (auto/on/off, default: auto) + Specifies whether the image file is protected with locks. + 'on' enables locking, preferring OFD (Open File Descriptor) + locks if available, but falling back to POSIX locks with a + warning. 'posix' forces the use of POSIX locks. 'auto' (the + default) enables locking only if OFD locks are available. + 'off' disables locking. (on/off/auto/posix, default: auto) =20 Example: =20 --=20 2.47.3 --=20 Quobyte GmbH, Berlin, AG Charlottenburg HRB 149012 B, Dr. Felix Hupfeld,=20 Dr. Bjoern Kolbeck