[libvirt] [PATCH 2/5] utils: Introduce virFileGetMPathTargets
This helper fetches targets for multipath devices.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/libvirt_private.syms | 1 +
src/util/virfile.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++++
src/util/virfile.h | 4 +++
3 files changed, 95 insertions(+)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 03fe3b315f..1bbff72263 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1773,6 +1773,7 @@ virFileGetACLs;
virFileGetHugepageSize;
virFileGetMountReverseSubtree;
virFileGetMountSubtree;
+virFileGetMPathTargets;
virFileHasSuffix;
virFileInData;
virFileIsAbsPath;
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
@@ -64,6 +64,10 @@
# include <sys/ioctl.h>
#endif
+#ifdef WITH_DEVMAPPER
+# include <libdevmapper.h>
+#endif
+
#include "configmake.h"
#include "intprops.h"
#include "viralloc.h"
@@ -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;
+}
+
+#else /* ! WITH_DEVMAPPER */
+
+int
+virFileGetMPathTargets(const char *path ATTRIBUTE_UNUSED,
+ unsigned long long **devs ATTRIBUTE_UNUSED,
+ size_t *ndevs ATTRIBUTE_UNUSED)
+{
+ errno = ENOSYS;
+ return -1;
+}
+#endif /* ! WITH_DEVMAPPER */
diff --git a/src/util/virfile.h b/src/util/virfile.h
index cd2a3867c2..0db8bf0b99 100644
--- a/src/util/virfile.h
+++ b/src/util/virfile.h
@@ -358,4 +358,8 @@ int virFileInData(int fd,
int *inData,
long long *length);
+int virFileGetMPathTargets(const char *path,
+ unsigned long long **devs,
+ size_t *ndevs);
+
#endif /* __VIR_FILE_H */
--
2.16.1