On Fri, Nov 22, 2013 at 08:20:30PM -0700, Eric Blake wrote:
> Putting together pieces from previous patches, it is now possible
> for 'virsh vol-dumpxml --pool gluster volname' to report metadata
> 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
> (virStorageBackendGlusterReadHeader): New helper function.
> (virStorageBackendGlusterRefreshVol): Probe non-raw files.
>
> Signed-off-by: Eric Blake <eblake@xxxxxxxxxx>
> ---
> src/storage/storage_backend_gluster.c | 76 ++++++++++++++++++++++++++++++++++-
> 1 file changed, 75 insertions(+), 1 deletion(-)
>
> diff --git a/src/storage/storage_backend_gluster.c b/src/storage/storage_backend_gluster.c
> index e935583..b239880 100644
> --- a/src/storage/storage_backend_gluster.c
> +++ b/src/storage/storage_backend_gluster.c
> @@ -147,6 +147,37 @@ error:
> }
>
>
> +static ssize_t
> +virStorageBackendGlusterReadHeader(glfs_fd_t *fd,
> + const char *name,
> + ssize_t maxlen,
> + char **buf)
> +{
> + char *s;
> + size_t nread = 0;
> +
> + 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;
> + }
Further down you're requesting O_NONBLOCK, and here you are
not handling EAGAIN explicitly. Is is desirable that we turn
EAGAIN into a fatal error, or should we remove the O_NONBLOCK
flag ?
> @@ -208,15 +243,54 @@ virStorageBackendGlusterRefreshVol(virStorageBackendGlusterStatePtr state,
> 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;
> + if (!(fd = glfs_open(state->vol, name, O_RDONLY| O_NONBLOCK | O_NOCTTY))) {
> + /* A dangling symlink now implies a TOCTTOU race; report it. */
> + virReportSystemError(errno, _("cannot open volume '%s'"), name);
> + goto cleanup;
> + }
Daniel
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