8:29 a.m.
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(a)redhat.com>
>> ---
>> 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).