[libvirt] [PATCHv3 4/4] storage: probe qcow2 volumes in gluster pool

[Peter Krempa]

On 11/12/13 05:19, Eric Blake wrote:
> Putting together pieces from previous patches, it is now possible
> for 'virsh dumpxml --pool gluster volname' to report metadata

Did you mean 'virsh vol-dumpxml --pool ... '?

> about a qcow2 file stored on gluster.  The backing file is still
> treated as raw; to fix that, more patches are needed to make the
> storage backing chain analysis recursive rather than halting at
> a network protocol name, but that work will not need any further
> calls into libgfapi so much as just reusing this code, and that
> should be the only code outside of the storage driver that needs
> any help from libgfapi.  Any additional use of libgfapi within
> libvirt should only be needed for implementing storage pool APIs
> such as volume creation or resizing, where backing chain analysis
> should be unaffected.
> 
> * src/storage/storage_backend_gluster.c
> (virStorageBackendGlusterOpen): Make relative name handling easier.
> (virStorageBackendGlusterReadHeader): New helper function.
> (virStorageBackendGlusterRefreshVol): Probe non-raw files.
> 
> Signed-off-by: Eric Blake <eblake at redhat.com>
> ---
>  src/storage/storage_backend_gluster.c | 87 +++++++++++++++++++++++++++++++++++
>  1 file changed, 87 insertions(+)
> 
> diff --git a/src/storage/storage_backend_gluster.c b/src/storage/storage_backend_gluster.c
> index bc90de9..69e8e61 100644
> --- a/src/storage/storage_backend_gluster.c
> +++ b/src/storage/storage_backend_gluster.c

...

> @@ -124,6 +130,37 @@ error:
>  }
> 
> 
> +static int

This function is declared as an int, but ...

> +virStorageBackendGlusterReadHeader(glfs_fd_t *fd,
> +                                   const char *name,
> +                                   int maxlen,
> +                                   char **buf)
> +{
> +    char *s;
> +    size_t nread = 0;

.. returns size_t. This could overflow normally, but is guarded by
maxlen. Okay.

> +
> +    if (VIR_ALLOC_N(*buf, maxlen) < 0)
> +        return -1;
> +
> +    s = *buf;
> +    while (maxlen) {
> +        ssize_t r = glfs_read(fd, s, maxlen, 0);
> +        if (r < 0 && errno == EINTR)
> +            continue;
> +        if (r < 0) {
> +            VIR_FREE(*buf);
> +            virReportSystemError(errno, _("unable to read '%s'"), name);
> +            return r;
> +        }
> +        if (r == 0)
> +            return nread;
> +        buf += r;
> +        maxlen -= r;
> +        nread += r;
> +    }
> +    return nread;
> +}
> +
>  /* Populate *volptr for the given name and stat information, or leave
>   * it NULL if the entry should be skipped (such as ".").  Return 0 on
>   * success, -1 on failure. */

...

> @@ -162,11 +203,57 @@ virStorageBackendGlusterRefreshVol(virStorageBackendGlusterStatePtr state,
>      }
>      state->uri->path = tmp;
> 
> +    if (!(fd = glfs_open(state->vol, name, O_RDONLY| O_NONBLOCK | O_NOCTTY))) {
> +        if ((errno == ENOENT || errno == ELOOP) &&
> +            S_ISLNK(st->st_mode)) {
> +            VIR_WARN("ignoring dangling symlink '%s'", name);
> +            ret = 0;
> +        } else {
> +            virReportSystemError(errno, _("cannot open volume '%s'"), name);
> +        }
> +        goto cleanup;
> +    }

Now that you actually open the volume file and probe it, you need to
kill the comment added in previous patch:

+    if (VIR_ALLOC(vol) < 0 ||
+        VIR_STRDUP(vol->name, name) < 0 ||
+        virAsprintf(&vol->key, "%s%s/%s",
+                    *pool == '/' ? "" : "/", pool, vol->name) < 0)
+        goto cleanup;
+
+    /* FIXME - must open files to determine if they are non-raw */
+    vol->type = VIR_STORAGE_VOL_NETWORK;
+    vol->target.format = VIR_STORAGE_FILE_RAW;
+    vol->capacity = vol->allocation = st->st_size;
+    tmp = state->uri->path;
+    state->uri->path = vol->key;
+    if (!(vol->target.path = virURIFormat(state->uri))) {
+        state->uri->path = tmp;
+        goto cleanup;

> +
> +    if ((len = virStorageBackendGlusterReadHeader(fd, name, len, &header)) < 0)
> +        goto cleanup;
> +
> +    if ((vol->target.format = virStorageFileProbeFormatFromBuf(name,
> +                                                               header,
> +                                                               len)) < 0 ||
> +        !(meta = virStorageFileGetMetadataFromBuf(name, header, len,
> +                                                  vol->target.format)))
> +        goto cleanup;

Also as you are erroring out in case of failure, you can remove the
lines setting some of the defaults.

> +
> +    if (meta->backingStore) {
> +        vol->backingStore.path = meta->backingStore;
> +        meta->backingStore = NULL;
> +        vol->backingStore.format = meta->backingStoreFormat;
> +        if (vol->backingStore.format < 0)
> +            vol->backingStore.format = VIR_STORAGE_FILE_RAW;
> +    }
> +    if (meta->capacity)
> +        vol->capacity = meta->capacity;
> +    if (meta->encrypted) {
> +        if (VIR_ALLOC(vol->target.encryption) < 0)
> +            goto cleanup;
> +        if (vol->target.format == VIR_STORAGE_FILE_QCOW ||
> +            vol->target.format == VIR_STORAGE_FILE_QCOW2)
> +            vol->target.encryption->format = VIR_STORAGE_ENCRYPTION_FORMAT_QCOW;
> +    }
> +    vol->target.features = meta->features;
> +    meta->features = NULL;
> +    vol->target.compat = meta->compat;
> +    meta->compat = NULL;
> +
>      *volptr = vol;
>      vol = NULL;
>      ret = 0;
>  cleanup:
> +    virStorageFileFreeMetadata(meta);
>      virStorageVolDefFree(vol);
> +    if (fd)
> +        glfs_close(fd);
> +    VIR_FREE(header);
>      return ret;
>  }
> 

ACK with the comment nit fixed.

Peter

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