[libvirt] [PATCH] Added timestamps to storage volumes
Eric Blake
eblake at redhat.com
Fri Jul 13 15:14:39 UTC 2012
On 07/13/2012 08:38 AM, Hendrik Schwartke wrote:
> !!! DON'T PUSH until stat-time lgpl 3 issue is fixed
> !!! To tests this change lgpl version to 3 in bootstrap.conf:176
>
> The access, birth, modification and change times are added to
> storage volumes and corresponding xml representations.
> ---
> bootstrap.conf | 1 +
> docs/formatstorage.html.in | 13 +++++++++++++
> docs/schemas/storagevol.rng | 36 ++++++++++++++++++++++++++++++++++++
> src/conf/storage_conf.c | 18 ++++++++++++++++++
> src/conf/storage_conf.h | 13 +++++++++++++
> src/storage/storage_backend.c | 6 ++++++
> 6 files changed, 87 insertions(+)
>
> diff --git a/bootstrap.conf b/bootstrap.conf
> index 9b42cbf..da0b960 100644
> --- a/bootstrap.conf
> +++ b/bootstrap.conf
> @@ -115,6 +115,7 @@ vc-list-files
> vsnprintf
> waitpid
> warnings
> +stat-time
> '
Insert in sorted order.
> @@ -172,6 +177,14 @@
> contains the MAC (eg SELinux) label string.
> <span class="since">Since 0.4.1</span>
> </dd>
> + <dt><code>timestamps</code></dt>
> + <dd>Provides timing information about the volume. The four sub elements
since btime is omitted on Linux, maybe this would read better as 'Up to
four sub-elements are present, where'
> + <code>atime</code>, <code>btime</code>, <code>ctime</code> and <code>mtime</code>
> + hold the access, birth, change and modification time of the volume, where known.
> + The used time format is <seconds>.<nanoseconds> since the beginning
> + of the epoch. This is a readonly attribute and is ignored when creating
> + a volume. <span class="since">Since 0.10.0</span>
> + <define name='timestamps'>
> + <optional>
> + <element name='timestamps'>
> + <optional>
> + <element name='atime'>
> + <data type="string">
> + <param name="pattern">[0-9]+\.[0-9]+</param>
> + </data>
It might be worth writing the regex to permit eliding the sub-second
resolution, on file systems that only have 1 second resolution. Given
that we are repeating this <data> four times, it might be worth defining
it, for a shorter diff:
<element name='atime'>
<ref name='timestamp'/>
</element>
...
<define name='timestamp'>
<data type='string'>
<param name='pattern'>[0-9]+(\.[0-9]+)?</param>
</data>
</define>
> +++ b/src/conf/storage_conf.c
> @@ -1277,6 +1277,24 @@ virStorageVolTargetDefFormat(virStorageVolOptionsPtr options,
>
> virBufferAddLit(buf," </permissions>\n");
>
> + virBufferAddLit(buf, " <timestamps>\n");
> + virBufferAsprintf(buf, " <atime>%llu.%ld</atime>\n",
> + (unsigned long long) def->timestamps.atime.tv_sec,
> + def->timestamps.atime.tv_nsec);
Eliding a sub-second suffix when tv_nsec == 0 would be easier with a
helper function:
void
virStorageVolTimestampFormat(virBufferPtr buf, const char *name,
struct timespec *ts)
{
if (ts->tv_nsec < 0)
return;
virBufferAsprintf(buf, " <%s>%llu", name,
(unsigned long long) ts->tv_sec);
if (ts->tv_nsec)
virBufferAsprintf(buf, ".%ld", tv->tv_nsec);
virBufferAsprintf(buf, "</%s>\n", name);
}
called as:
virStorageVolTimestampFormat(buf, "atime", &def->timestamps.atime);
virStorageVolTimestampFormat(buf, "atime", &def->timestamps.btime);
and so on.
Actually, I'd list atime, mtime, ctime, btime - in that order - rather
than trying to sort the names alphabetically (that is, match typical
'struct stat' ordering).
> +typedef virStorageTimestamps *virStorageTimestampsPtr;
> +struct _virStorageTimestamps {
> + struct timespec atime;
> + /* if btime.tv_sec == -1 && btime.tv_nsec == -1 than
> + * birth time is unknown
Doesn't gnulib guarantee that tv_nsec == -1 in isolation is sufficient
to point out an unknown value? That is, checking tv_sec == -1 is overhead.
Looking nicer. I'll have to ping upstream on gnulib about the last
holdout on the relicensing of stat-time; and I'm also still waiting for
the security fix in updated automake to hit Fedora.
--
Eric Blake eblake at redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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