Libguestfs - Jul 2023 - [PATCH libguestfs] daemon: lvm: Do reverse device name translation on pvs_full device fields

Intermittent test failures in virt-filesystems showed that when using
the pvs_full API, the pv_name field in the returned list of structures
was not being reverse translated.  As a result internal partition
names could appear in the output of virt-filesystems.

See: https://listman.redhat.com/archives/libguestfs/2023-July/032058.html
---
 daemon/lvm.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/daemon/lvm.c b/daemon/lvm.c
index 7e76e17ccc..b8c01f718c 100644
--- a/daemon/lvm.c
+++ b/daemon/lvm.c
@@ -146,7 +146,34 @@ do_vgs (void)
 guestfs_int_lvm_pv_list *
 do_pvs_full (void)
 {
-  return parse_command_line_pvs ();
+  guestfs_int_lvm_pv_list *r;
+  size_t i;
+  char *din, *dout;
+
+  r = parse_command_line_pvs ();
+  if (r == NULL)
+    /* parse_command_line_pvs has already called reply_with_error */
+    return NULL;
+
+  /* The pv_name fields contain device names which must be reverse
+   * translated.  The problem here is that the generator does not have
+   * a "FMountable" field type in types.mli.
+   */
+  for (i = 0; i < r->guestfs_int_lvm_pv_list_len; ++i) {
+    din = r->guestfs_int_lvm_pv_list_val[i].pv_name;
+    if (din) {
+      dout = reverse_device_name_translation (din);
+      if (!dout) {
+        /* reverse_device_name_translation has already called
reply_with_error*/
+        /* XXX memory leak here */
+        return NULL;
+      }
+      r->guestfs_int_lvm_pv_list_val[i].pv_name = dout;
+      free (din);
+    }
+  }
+
+  return r;
 }
 
 guestfs_int_lvm_vg_list *
-- 
2.41.0

This is another failure, this time in virt-diff (see attachment for
full build log).

virt-diff works by opening two handles to different disk images and
the comparing the filesystems in each.  When we stat files in the two
handles:

  handle 'g1' returns st_dev = 2065 [8:17, /dev/sdb1]
  handle 'g2' returns st_dev = 2049 [8:1, /dev/sda1]

(for files under the /boot mountpoint).

Indeed looking at the log we can see that (as in the previous case)
/dev/sda and /dev/sdb are swapped.

Reverse device name translation has never even considered the case of
rewriting st_dev numbers, but I guess we'll have to do that now.

I wonder why this has suddenly started happening.  Kernel update?
I cannot reproduce it locally.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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Upstream in commit 32cb5b45cf.

I tested this using guestfs-tools & virt-v2v and nothing failed.
However I was never able to reproduce the original issue.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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