[libvirt] [PATCH 2/2] fs: Fix probing on no-overwrite of target device

[John Ferlan]

https://bugzilla.redhat.com/show_bug.cgi?id=1363586

There's actually a couple of bugs here...

    only the "input" format type, so any other "types" of format would be
    filtered during the blkid_do_probe resulting in allowing a new format
    type to overwrite a previous format type since when it's determined a
    format type cannot be determined that we'd return 0 (or prior to the
    previous patch a NOT_FOUND value). So instead of passing just one type
    to filter on, pass the entire list of virStoragePoolFormatFileSystem
    types. According to recent docs, this call may be unnecessary unless
    we care about superblock probing only. Ironically, if the on disk
    format type was the same as the requested format, the code would then
    fail on the else condition (fixed in #2).

    was returning -1 (or prior to previous patch FOUND) with an error
    which caused the caller to just fail. So even though it was found
    it did nothing.  Change that to compare the on disk type with the
    passed format type and return 0 or -1 as necessary.

Signed-off-by: John Ferlan <jferlan at redhat.com>
---
 src/storage/storage_backend_fs.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/src/storage/storage_backend_fs.c b/src/storage/storage_backend_fs.c
index 2413e82..74b278d 100644
--- a/src/storage/storage_backend_fs.c
+++ b/src/storage/storage_backend_fs.c
@@ -626,7 +626,8 @@ virStorageBackendFileSystemProbe(const char *device,
     int ret = -1;
     blkid_probe probe = NULL;
     const char *fstype = NULL;
-    char *names[2], *libblkid_format = NULL;
+    size_t i;
+    const char *names[VIR_STORAGE_POOL_FS_LAST] = {0};
 
     VIR_DEBUG("Probing for existing filesystem of type %s on device %s",
               format, device);
@@ -648,25 +649,26 @@ virStorageBackendFileSystemProbe(const char *device,
         goto error;
     }
 
-    if (VIR_STRDUP(libblkid_format, format) < 0)
-        goto error;
-
-    names[0] = libblkid_format;
-    names[1] = NULL;
+    for (i = 1; i < VIR_STORAGE_POOL_FS_LAST; i++)
+        names[i - 1] = virStoragePoolFormatFileSystemTypeToString(i);
 
     blkid_probe_filter_superblocks_type(probe,
                                         BLKID_FLTR_ONLYIN,
-                                        names);
+                                        (char **)names);
 
     if (blkid_do_probe(probe) != 0) {
         VIR_INFO("No filesystem of type '%s' found on device '%s'",
                  format, device);
         ret = 0;
     } else if (blkid_probe_lookup_value(probe, "TYPE", &fstype, NULL) == 0) {
-        virReportError(VIR_ERR_STORAGE_POOL_BUILT,
-                       _("Existing filesystem of type '%s' found on "
-                         "device '%s'"),
-                       fstype, device);
+        if (STRNEQ(fstype, format)) {
+            virReportError(VIR_ERR_STORAGE_POOL_BUILT,
+                           _("Existing filesystem of type '%s' found on "
+                             "device '%s'"),
+                           fstype, device);
+        } else {
+            ret = 0;
+        }
     }
 
     if (blkid_do_probe(probe) != 1) {
@@ -677,8 +679,6 @@ virStorageBackendFileSystemProbe(const char *device,
     }
 
  error:
-    VIR_FREE(libblkid_format);
-
     if (probe != NULL)
         blkid_free_probe(probe);
 
-- 
2.7.4