[libvirt] [PATCH v4 2/4] storage: report error rather than warning if backing files doesn't exist

[Guannan Ren]

On 07/15/2013 09:31 PM, Martin Kletzander wrote:
> s/doesn't/don't/ in $SUBJ
>
> On 07/02/2013 11:35 AM, Guannan Ren wrote:
>> If one of backing files for disk source doesn't exist, the guest will not
>> be able to find and use the disk even though the disk still exists in
>> guest xml definition. So reporting an error make more sense.
>>
>> Adding virFileAccessibleAs() to check if the backing file described in
>> disk meta exist in real path. If not, report error. the uid and gid
> s/exist/exists/; s/the/The/
>
>> arguments don't have so much meannings for F_OK, so give 0 for them.
> s/meannings/meaning/
>
>> ---
>>   src/util/virstoragefile.c | 23 +++++++++++++++--------
>>   tests/virstoragetest.c    | 16 ++++++++--------
>>   2 files changed, 23 insertions(+), 16 deletions(-)
>>
>> diff --git a/src/util/virstoragefile.c b/src/util/virstoragefile.c
>> index 27aa4fe..cb61e5b 100644
>> --- a/src/util/virstoragefile.c
>> +++ b/src/util/virstoragefile.c
>> @@ -580,6 +580,13 @@ virFindBackingFile(const char *start, bool start_is_dir, const char *path,
>>           goto cleanup;
>>       }
>>   
>> +    if (virFileAccessibleAs(combined, F_OK, 0, 0) < 0) {
>> +        virReportSystemError(errno,
>> +                             _("Backing file '%s' does not exist"),
>> +                             combined);
>> +        goto cleanup;
>> +    }
>> +
> Pre-existing, but this nad other errors will be shadowed by the error in
> qemuDomainBlockCommit.  The existence of the file is already checked by:
>
>>       if (!(*canonical = canonicalize_file_name(combined))) {
> this ^^ line, so no need to call virFileAccessibleAs().

Calling virFileAccessibleAs() here is for more clear error message.


>
>>           virReportSystemError(errno,
>>                                _("Can't canonicalize path '%s'"), path);
>> @@ -870,14 +877,10 @@ virStorageFileGetMetadataInternal(const char *path,
>>                                          !!directory, backing,
>>                                          &meta->directory,
>>                                          &meta->backingStore) < 0) {
>> -                    /* the backing file is (currently) unavailable, treat this
>> -                     * file as standalone:
>> -                     * backingStoreRaw is kept to mark broken image chains */
>> -                    meta->backingStoreIsFile = false;
>> -                    backingFormat = VIR_STORAGE_FILE_NONE;
>> -                    VIR_WARN("Backing file '%s' of image '%s' is missing.",
>> -                             meta->backingStoreRaw, path);
>> -
>> +                    VIR_ERROR(_("Backing file '%s' of image '%s' is missing."),
>> +                              meta->backingStoreRaw, path);
>> +                    VIR_FREE(backing);
>> +                    goto cleanup;
> And then you report one more error here, even though the function may
> fail because of something else.  I'd guess that's why it was a warning.
> No idea why it skipped the errors, though.
>
> The errors should be fixed, but this patch just adds more confusion to
> the error reporting.

no, VIR_ERROR just adds one more error log item, the actual raised error 
is still there not being shadowed.

Guannan