On Tue, Nov 24, 2020 at 15:25:01 -0600, Dustan B Helm wrote: > On Tue, Nov 24, 2020 at 12:59 AM Peter Krempa <pkrempa@xxxxxxxxxx> wrote: > > On Mon, Nov 23, 2020 at 17:17:15 -0600, Dustan B Helm wrote: [...] > > We found methods to convert user and group strings into integer IDs in > src/util/virutil.c (the getUserID and getGroupID methods). We plan on > checking if the parameter provided has a + at the front of the string, in > which case we will call these methods to convert the user or group name > into an ID. virGetUserID/virGetGroupID have internal handling of the '+' prefix. You can use them without adding any logic on top. > However, we aren’t sure where the _virStorageSource data is > actually being initialized. We found the > qemuBlockStorageSourceGetBackendProps method in src/qemu/qemu_block.c, for > which we would need to provide an NFS props method. qemuBlockStorageSourceGetBackendProps is the place that convers virStorageSource to a JSON object describing the source. Please note that this function is not the place for any logic such as the translation from username to the uid number. The function shall take a virStorageSource and output a JSON struct, that's all. > At this point we need > the _virStorageSource to be initialized and contain the nfs_user and > nfs_group parameters, but we can’t find where to actually set these. You > had mentioned some kind of parser in domain_conf.c, but since domain_conf > is an extensive file, we had some trouble narrowing down our concerns to a > specific parsing/formatting mechanism. What method(s) would we change here? > Would that be satisfactory to set our _virStorageSource for use in the JSON > initialization? There are two steps here: 1) you must parse/format the XML bits into a virStorage source This is done in src/conf/domain_conf.c. Specifically you are dealing with a storage source so the relevant functions are: virDomainDiskSourceFormat and virDomainStorageSourceParse 2) The actual lookup from username/groupname to uid/gid qemuDomainPrepareStorageSourceBlockdev The two steps above means that you actually will have to add 4 fields to virStorageSource. 2 strings for the values from the XML parser and then 2 integers for internal use for the virStorageSource -> JSON conversion. Some notes: - make sure that patches are split into logical parts and the code compiles successfully after every patch as per contributor guidelines https://www.libvirt.org/coding-style.html https://www.libvirt.org/hacking.html - when you add VIR_STORAGE_NET_PROTOCOL_NFS to enum virStorageNetProtocol there will be a lot of places the compiler will notify that need to be changed. Don't try to implement all of them at once. Add the entry to the switch statement and come back to comply with splitting the patch into logical pieces - any XML addition requires tests to be added In this case you'll be also needing to add a qemu commandline test later so I suggest you add your XML test as a new file to: tests/qemuxml2argvdata, and enable the test in tests/qemuxml2xmltest.c (output file is stored in tests/qemuxml2xmloutdata, you can also run the test with VIR_TEST_REGENREATE_OUTPUT=1 env variable set which generates the proper output file) Always use one of the _CAPS_LATEST macros for invoking the test regardless of prior art. You can add multiple disks to the tested XML to test any combination of the <nfs> parameters. Please make sure to list at least one example of the NFS disk being a <backingStore> of a <source> (see tests/qemuxml2argvdata/disk-backing-chains.xml for inspiration) Don't forget to also document the new elements in docs/formatdomain.rst - you'll also need to add proper backing store string parser (virStorageSourceJSONDriverParser). Tests for the parser are in tests/virstoragetest.c invoked via TEST_BACKING_PARSE - there's no need to add a specific capability for the NFS protocol as it predates libvirt's use of -blockdev (QEMU_CAPS_BLOCKDEV). You have to add a check for it to qemuDomainValidateStorageSource based on the above capabapility. Don't bother with a negative test case for this. - Enabling support for external snapshots stored on NFS requires that you also implement the support for blockdev-create (qemuBlockStorageSourceCreateGetStorageProps, tests are in tests/qemublocktest.c invoked via TEST_IMAGE_CREATE) - once you add qemuBlockStorageSourceGetBackendProps, enable the test case added for qemuxml2xmltest.c above also for qemuxml2argvtest.c You can use the same trick with VIR_TEST_REGENERATE_OUTPUT env variable to obtain the output file. As noted, use _CAPS_LATEST macros to invoke the test. qemuBlockStorageSourceGetBackendProps was historically tested by TEST_DISK_TO_JSON cases in tests/qemublocktest.c for compliance with the qemu monitor protocol schema, but that's no longer required. qemuxml2argvtest does the same check for every <disk> - add an entry to NEWS.rst outlining the addintion (separate commit)
