On Wed, Jan 27, 2016 at 09:04:45AM -0500, John Ferlan wrote:
>
>
> On 01/26/2016 09:46 AM, Pavel Hrdina wrote:
> > On Fri, Jan 22, 2016 at 05:21:04PM -0500, John Ferlan wrote:
> >> Create a helper routine in order to parse the 'device' string contained
> >> within the generated 'lvs' output string.
> >>
> >> A future patch would then be able to avoid the code more cleanly
> >>
> >> Signed-off-by: John Ferlan <jferlan@xxxxxxxxxx>
> >> ---
> >> src/storage/storage_backend_logical.c | 186 +++++++++++++++++++---------------
> >> 1 file changed, 104 insertions(+), 82 deletions(-)
> >>
> >> diff --git a/src/storage/storage_backend_logical.c b/src/storage/storage_backend_logical.c
> >> index 76ea00a..bf67faf 100644
> >> --- a/src/storage/storage_backend_logical.c
> >> +++ b/src/storage/storage_backend_logical.c
> >> @@ -72,21 +72,115 @@ struct virStorageBackendLogicalPoolVolData {
> >> };
> >>
> >> static int
> >> -virStorageBackendLogicalMakeVol(char **const groups,
> >> - void *opaque)
> >> +virStorageBackendLogicalParseVolDevice(virStorageVolDefPtr vol,
> >> + char **const groups,
> >> + int nextents,
> >> + unsigned long long size,
> >> + unsigned long long length)
> >> {
> >
> > You've called the new helper *ParseVolDevice, but it actually does more than
> > that. I would rather see it like ParseExtents and also move all the extents
> > related code into this function (parsing length and size)
>
> OK - my goal was to just parse the devices/extents element so that the
> next patch could use the 'nextents' to decide whether to call it... The
> 'nextents' is just the count... Having more than 1 is seen in a
> 'striped' and 'mirror' lv. A 'thin' lv has 0... A 'thin-pool' and
> 'linear' each has 1... Names are found in the 'segtype' field, but it's
> otherwise useless. Perhaps originally the thought when adding a parse of
> that field was that the 'stripes' value only was valid for stripes and
> mirrors, but it seems it's set depending on the count of devices - so it
> seems safe to use it for the extents parsing.
>
> FWIW: The "extents" look like:
>
> /dev/hda2(0) <--- linear
>
> or
>
> /dev/sdc1(10240),/dev/sdd1(0) <--- striped
>
> or
>
> thinpool_lv_test_thin_tdata(0) <--- thin-pool
>
>
> The "extents" gets further 'regcomp' and 'regexec''d to grab that "(#)"
> which is part of the black magic that I cannot explain ;-)
Yes, I understand why the next patch updates the way, that we don't assume there
is always 1 extent. It just seemed to me that parsing length and size would be
nice to move to that function as it's used only in that function.
>
> >
> > [...]
> >
> >> + /* vars[0] is skipped */
> >> + for (i = 0; i < nextents; i++) {
> >> + size_t j;
> >> + int len;
> >> + char *offset_str = NULL;
> >> +
> >> + j = (i * 2) + 1;
> >> + len = vars[j].rm_eo - vars[j].rm_so;
> >> + p[vars[j].rm_eo] = '\0';
> >> +
> >> + if (VIR_STRNDUP(vol->source.extents[vol->source.nextent].path,
> >> + p + vars[j].rm_so, len) < 0)
> >> + goto cleanup;
> >> +
> >> + len = vars[j + 1].rm_eo - vars[j + 1].rm_so;
> >> + if (VIR_STRNDUP(offset_str, p + vars[j + 1].rm_so, len) < 0)
> >> + goto cleanup;
> >> +
> >> + if (virStrToLong_ull(offset_str, NULL, 10, &offset) < 0) {
> >> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> >> + _("malformed volume extent offset value"));
> >> + VIR_FREE(offset_str);
> >> + goto cleanup;
> >> + }
> >> +
> >> + VIR_FREE(offset_str);
> >> +
> >> + vol->source.extents[vol->source.nextent].start = offset * size;
> >> + vol->source.extents[vol->source.nextent].end = (offset * size) + length;
> >> + vol->source.nextent++;
> >
> > This would be much nicer to be done using VIR_APPEND_ELEMENT(). I know that
> > this commit is just a code movement so this should be done in separate commit.
> >
>
> Yes I pretty much blindly moved "just" the devices parsing code, but I
> will note that we're not appending here - it's filling it in. Back in
> the caller "vol->source.extents" is allocated using
> "vol->source.nextents + nextents". A "new" vol would have
> "source.nextents == 0". All this loop does is fill in each
> source.extents and bump the source.nextents.
Yes, I know that we are not appending but filling existing array that was
allocated earlier, I just didn't mentioned it. But we don't need to
pre-allocate the array but just simply use append_element. The main point was
that the allocation is again outside of the new function and that's not a good
practice.
> In any case, I will move the allocation of source.extents, fetch of
> length and size into the helper (and rename it).
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