In our multipath case, the initial open succeeds (it's not locked by anything else) and the second lock attempt fails, however, IIUC the fcntl structure[1] includes the locking pid, which should be our invocation of QEMU;
Can we not check if the locking pid matches the current pid and not fail? This appears to be the original goal of protecting locked images from being manipulated by external processes. -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1716028 Title: qemu 2.10 locks images with no feature flag Status in QEMU: New Status in qemu package in Ubuntu: New Bug description: 1) % lsb_release -rd Description: Ubuntu Artful Aardvark (development branch) Release: 17.10 2) % apt-cache policy qemu-system-x86 qemu-system-x86: Installed: 1:2.10~rc3+dfsg-0ubuntu1 Candidate: 1:2.10+dfsg-0ubuntu1 Version table: 1:2.10+dfsg-0ubuntu1 500 500 http://archive.ubuntu.com//ubuntu devel/main amd64 Packages *** 1:2.10~rc3+dfsg-0ubuntu1 100 100 /var/lib/dpkg/status 3) qemu locks image files with no way to discover this feature nor how to disable it 4) qemu provides a way to query if it supports image locking, and what the default value is, and how to disable the locking via cli qemu 2.10 now will lock image files and warn if an image is currently locked. This prevent qemu from running (and possibly corrupting said image). However, qemu does not provide any way to determine if a qemu binary actually has this capability. Normally behavior changing features are exposed via some change to the qemu help menu or QMP/QAPI output of capabilities. I believe this slipped through since libvirt already does image locking, but direct cli users will be caught by this change. In particular, we have a use-case where we simulate multipath disks by creating to disks which point to the same file which now breaks without adding the 'file.locking=off' to the -drive parameters; which is also completely undocumented and unexposed. Some parts of the cli like -device allow querying of settable options (qemu-system-x86 -device scsi_hd,?) but nothing equivalent exists for -drive parameters. ProblemType: Bug DistroRelease: Ubuntu 17.10 Package: qemu-system-x86 1:2.10~rc3+dfsg-0ubuntu1 ProcVersionSignature: Ubuntu 4.12.0-11.12-generic 4.12.5 Uname: Linux 4.12.0-11-generic x86_64 NonfreeKernelModules: zfs zunicode zavl zcommon znvpair ApportVersion: 2.20.6-0ubuntu7 Architecture: amd64 Date: Fri Sep 8 12:56:53 2017 JournalErrors: Hint: You are currently not seeing messages from other users and the system. Users in groups 'adm', 'systemd-journal' can see all messages. Pass -q to turn off this notice. -- Logs begin at Mon 2017-01-30 11:56:02 CST, end at Fri 2017-09-08 12:56:46 CDT. -- -- No entries -- KvmCmdLine: COMMAND STAT EUID RUID PID PPID %CPU COMMAND MachineType: HP ProLiant DL360 Gen9 ProcEnviron: TERM=xterm PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.12.0-11-generic root=UUID=45354276-e0c0-4bf6-9083-f130b89411cc ro --- console=ttyS1,115200 SourcePackage: qemu UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 03/05/2015 dmi.bios.vendor: HP dmi.bios.version: P89 dmi.chassis.type: 23 dmi.chassis.vendor: HP dmi.modalias: dmi:bvnHP:bvrP89:bd03/05/2015:svnHP:pnProLiantDL360Gen9:pvr:cvnHP:ct23:cvr: dmi.product.family: ProLiant dmi.product.name: ProLiant DL360 Gen9 dmi.sys.vendor: HP To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1716028/+subscriptions
