Re: [libvirt] [PATCH 2/5] utils: Introduce virFileGetMPathTargets

This helper fetches targets for multipath devices. Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/libvirt_private.syms | 1 + src/util/virfile.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++++ src/util/virfile.h | 4 +++ 3 files changed, 95 insertions(+)

diff --git a/src/util/virfile.c b/src/util/virfile.c index 5e9bd2007a..f89e4bd823 100644 --- a/src/util/virfile.c +++ b/src/util/virfile.c

@@ -4227,3 +4231,89 @@ virFileWaitForExists(const char *path, return 0; } + + +#ifdef WITH_DEVMAPPER +/** + * virFileGetMPathTargets: + * @path: multipath device + * @devs: returned array of st_rdevs of @path targets + * @ndevs: size of @devs and @devNames

+ * + * For given @path figure out its targets, and store them in + * @devs. Items from @devs are meant to be used in + * minor() and major() to receive device MAJ:MIN pairs. + * + * If @path is not a multipath device, @ndevs is set to 0 and + * success is returned. + * + * If we don't have permissions to talk to kernel, -1 is returned + * and errno is set to EBADF.

+ * + * Returns 0 on success, -1 otherwise. + */ +int +virFileGetMPathTargets(const char *path, + unsigned long long **devs,

+ size_t *ndevs) +{ + struct dm_deps *deps; + struct dm_task *dmt; + struct dm_info info; + size_t i; + int ret = -1; + + *ndevs = 0; + + if (!(dmt = dm_task_create(DM_DEVICE_DEPS))) + goto cleanup; + + if (!dm_task_set_name(dmt, path)) { + if (errno == ENOENT) { + /* It's okay, @path is not managed by devmapper => + * not a multipath device. */ + ret = 0; + } + goto cleanup; + } + + dm_task_no_open_count(dmt); + + if (!dm_task_run(dmt)) + goto cleanup; + + if (!dm_task_get_info(dmt, &info)) + goto cleanup; + + if (!info.exists) { + ret = 0; + goto cleanup; + } + + if (!(deps = dm_task_get_deps(dmt))) + goto cleanup; + + if (VIR_ALLOC_N(*devs, deps->count) < 0)

+ goto cleanup; + *ndevs = deps->count; + + for (i = 0; i < deps->count; i++) + (*devs)[i] = deps->device[i]; + + ret = 0; + cleanup: + dm_task_destroy(dmt); + return ret; +}