Re: [libvirt] [PATCH] qemuDomainGetPreservedMounts: Fetch list of /dev/* mounts dynamically

With my namespace patches, we are spawning qemu in its own namespace so that we can manage /dev entries ourselves. However, some filesystems mounted under /dev needs to be preserved in order to be shared with the parent namespace (e.g. /dev/pts). Currently, the list of mount points to preserve is hardcoded which ain't right - on some systems there might be less or more items under real /dev that on our list. The solution is to parse /proc/mounts and fetch the list from there. Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/qemu/qemu_domain.c | 126 +++++++++++++++++++++++++++++++------------------ 1 file changed, 81 insertions(+), 45 deletions(-) diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index 67e8836f3b..e0631bf55a 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -200,33 +194,73 @@ qemuDomainEnableNamespace(virDomainObjPtr vm, } +/** + * qemuDomainGetPreservedMounts: + * + * Process list of mounted filesystems and: + * a) save all FSs mounted under /dev to @devPath + * b) generate backup path for all the entries in a) + * + * Any of the return pointers can be NULL. + * + * Returns 0 on success, -1 otherwise (with error reported) + */ static int qemuDomainGetPreservedMounts(virQEMUDriverPtr driver, virDomainObjPtr vm, - char ***devMountsPath, - size_t *ndevMountsPath) + char ***devPath, + char ***devSavePath, + size_t *ndevPath) { virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver); - char **paths; - size_t i; + char **paths = NULL, **mounts = NULL; + size_t i, nmounts; - if (VIR_ALLOC_N(paths, ARRAY_CARDINALITY(devPreserveMounts)) < 0) + if (virFileGetMountSubtree(PROC_MOUNTS, "/dev", + &mounts, &nmounts) < 0) goto error; - for (i = 0; i < ARRAY_CARDINALITY(devPreserveMounts); i++) { + if (!nmounts) { + if (ndevPath) + *ndevPath = 0; + return 0; + } + + /* Okay, this is crazy. But virFileGetMountSubtree() fetched us all the + * mount points under /dev including /dev itself. Fortunately, the paths + * are sorted based in their length so we skip the first one (/dev) as it