[PATCH pve-storage 5/5] add volume_underlay_shrink

[Alexandre Derumier]

reduce underlay volume size to minimum used

Signed-off-by: Alexandre Derumier <alexandre.derumier at groupe-cyllene.com>
---
 src/PVE/Storage.pm                | 15 +++++++++++++++
 src/PVE/Storage/LVMQcow2Plugin.pm | 31 +++++++++++++++++++++++++++++++
 src/PVE/Storage/Plugin.pm         |  7 +++++++
 3 files changed, 53 insertions(+)

diff --git a/src/PVE/Storage.pm b/src/PVE/Storage.pm
index 367b672..f3c1a2c 100755
--- a/src/PVE/Storage.pm
+++ b/src/PVE/Storage.pm
@@ -335,6 +335,21 @@ sub volume_underlay_resize {
     }
 }
 
+sub volume_underlay_shrink {
+    my ($cfg, $volid) = @_;
+
+    my ($storeid, $volname) = parse_volume_id($volid, 1);
+    if ($storeid) {
+	my $scfg = storage_config($cfg, $storeid);
+	my $plugin = PVE::Storage::Plugin->lookup($scfg->{type});
+	return $plugin->volume_underlay_shrink($scfg, $storeid, $volname);
+    } elsif ($volid =~ m|^(/.+)$| && -e $volid) {
+	die "trim file/device '$volid' is not possible\n";
+    } else {
+	die "unable to parse volume ID '$volid'\n";
+    }
+}
+
 sub volume_rollback_is_possible {
     my ($cfg, $volid, $snap, $blockers) = @_;
 
diff --git a/src/PVE/Storage/LVMQcow2Plugin.pm b/src/PVE/Storage/LVMQcow2Plugin.pm
index 2c17c69..7780270 100644
--- a/src/PVE/Storage/LVMQcow2Plugin.pm
+++ b/src/PVE/Storage/LVMQcow2Plugin.pm
@@ -4,6 +4,7 @@ use strict;
 use warnings;
 
 use IO::File;
+use JSON qw(from_json);
 
 use PVE::Tools qw(run_command trim);
 use PVE::Storage::Plugin;
@@ -203,6 +204,36 @@ sub volume_underlay_resize {
     run_command($cmd, errmsg => "error resizing volume '$path'");
 }
 
+sub volume_underlay_shrink {
+    my ($class, $scfg, $storeid, $volname) = @_;
+
+    return if !$scfg->{sparse};
+
+    my ($allocated_size, $format , $required_size, undef) = volume_size_info($class, $scfg, $storeid, $volname, 5);
+
+    #don't reduce if it's full allocated
+    return if $required_size == $allocated_size;
+
+    if(!$required_size) {
+	warn "can't get required size, skip shrinking" if !$required_size;
+    }
+
+    my $chunksize = $scfg->{chunksize} // 1;
+    $chunksize *= 1073741824;
+    my $size = $required_size + $chunksize;
+    my $padding = (1024 - $size % 1024) % 1024;
+    $size = $size + $padding;
+    $size = ($size/1024/1024) . "M";
+
+    my $path = $class->filesystem_path($scfg, $volname);
+
+    my $cmd = ['/sbin/lvreduce', '-y', '-L', $size, $path];
+    eval {
+	run_command($cmd, errmsg => "error shrinking volume '$path'");
+    };
+    warn $@ if $@;
+}
+
 sub refresh_volume {
     my ($class, $storeid, $scfg, $volname) = @_;
 
diff --git a/src/PVE/Storage/Plugin.pm b/src/PVE/Storage/Plugin.pm
index 8ff9fbd..13b049e 100644
--- a/src/PVE/Storage/Plugin.pm
+++ b/src/PVE/Storage/Plugin.pm
@@ -1078,6 +1078,13 @@ sub volume_underlay_resize {
     return undef;
 }
 
+sub volume_underlay_shrink {
+    my ($class, $scfg, $storeid, $volname) = @_;
+
+    # do nothing by default
+    return undef;
+}
+
 sub volume_snapshot {
     my ($class, $scfg, $storeid, $volname, $snap) = @_;
 
-- 
2.39.2