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

[Martin Kletzander]

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().

>          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.

Martin