common: introduce common module

This module's purpose is to provide shared functions, constants, etc.
for storage plugins and storage-related operations.

It starts out with a align_size_up() function, that will (initially)
be used for volume import.

[FE: start out with a different function for my use case
     fixup Makefile]

Originally-by: Max Carrara <m.carrara@proxmox.com>
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>

src/PVE/Storage/Common.pm

@@ -0,0 +1,54 @@
+package PVE::Storage::Common;
+
+use strict;
+use warnings;
+
+=pod
+
+=head1 NAME
+
+PVE::Storage::Common - Shared functions and utilities for storage plugins and storage operations
+
+=head1 DESCRIPTION
+
+This module contains common subroutines that are mainly to be used by storage
+plugins. This module's submodules contain subroutines that are tailored towards
+a more specific or related purpose.
+
+Functions concerned with storage-related C<PVE::SectionConfig> things, helpers
+for the C<PVE::Storage> API can be found in this module. Functions that can't
+be grouped in a submodule can also be found here.
+
+=head1 SUBMODULES
+
+=over
+
+=back
+
+=head1 FUNCTIONS
+
+=cut
+
+=pod
+
+=head3 align_size_up
+
+    $aligned_size = align_size_up($size, $granularity)
+
+Returns the next size bigger than or equal to C<$size> that is aligned with a
+granularity of C<$granularity>. Prints a message if the aligned size is not
+equal to the aligned size.
+
+=cut
+
+sub align_size_up : prototype($$) {
+    my ($size, $granularity) = @_;
+
+    my $padding = ($granularity - $size % $granularity) % $granularity;
+    my $aligned_size = $size + $padding;
+    print "size $size is not aligned to granularity $granularity, rounding up to $aligned_size\n"
+	if $aligned_size != $size;
+    return $aligned_size;
+}
+
+1;

src/PVE/Storage/Common/Makefile

@@ -0,0 +1,6 @@
+SOURCES = \
+
+
+.PHONY: install
+install:
+	for i in ${SOURCES}; do install -D -m 0644 $$i ${DESTDIR}${PERLDIR}/PVE/Storage/Common/$$i; done

src/PVE/Storage/Makefile

@@ -1,4 +1,5 @@
 SOURCES= \
+	Common.pm \
 	Plugin.pm \
 	DirPlugin.pm \
 	LVMPlugin.pm \
@@ -18,5 +19,6 @@ SOURCES= \
 
 .PHONY: install
 install:
+	make -C Common install
 	for i in ${SOURCES}; do install -D -m 0644 $$i ${DESTDIR}${PERLDIR}/PVE/Storage/$$i; done
 	make -C LunCmd install