[pve-devel] [PATCH storage 1/1] fix #3580: plugins: make preallocation mode selectable for qcow2 and raw images

[Lorenz Stechauner]

the plugins for file based storages
 * BTRFS
 * CIFS
 * Dir
 * Glusterfs
 * NFS
now allow the option 'preallocation'.

'preallocation' can have four values:
 * default
 * off
 * metadata
 * falloc
 * full
see man pages for `qemu-img` for what these mean exactly. [0]

the defualt value was chosen to be
 * qcow2: metadata (as previously)
 * raw: off (I was unable to find any documentation on this, so
    could only test this and found, that 'off' was the most
    fitting.)

when using 'metadata' as preallocation mode, for raw images 'off'
is used.

[0] https://qemu.readthedocs.io/en/latest/system/images.html#disk-image-file-formats

Signed-off-by: Lorenz Stechauner <l.stechauner at proxmox.com>
---
 PVE/Storage/BTRFSPlugin.pm     |  1 +
 PVE/Storage/CIFSPlugin.pm      |  1 +
 PVE/Storage/DirPlugin.pm       |  1 +
 PVE/Storage/GlusterfsPlugin.pm |  4 ++-
 PVE/Storage/NFSPlugin.pm       |  1 +
 PVE/Storage/Plugin.pm          | 46 +++++++++++++++++++++++++++++++++-
 6 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/PVE/Storage/BTRFSPlugin.pm b/PVE/Storage/BTRFSPlugin.pm
index fe42082..31a2954 100644
--- a/PVE/Storage/BTRFSPlugin.pm
+++ b/PVE/Storage/BTRFSPlugin.pm
@@ -73,6 +73,7 @@ sub options {
 	is_mountpoint => { optional => 1 },
 	nocow => { optional => 1 },
 	mkdir => { optional => 1 },
+	preallocation => { optional => 1 },
 	# TODO: The new variant of mkdir with  `populate` vs `create`...
     };
 }
diff --git a/PVE/Storage/CIFSPlugin.pm b/PVE/Storage/CIFSPlugin.pm
index 0221069..2d94413 100644
--- a/PVE/Storage/CIFSPlugin.pm
+++ b/PVE/Storage/CIFSPlugin.pm
@@ -140,6 +140,7 @@ sub options {
 	smbversion => { optional => 1},
 	mkdir => { optional => 1 },
 	bwlimit => { optional => 1 },
+	preallocation => { optional => 1 },
     };
 }
 
diff --git a/PVE/Storage/DirPlugin.pm b/PVE/Storage/DirPlugin.pm
index 2267f11..3eeec98 100644
--- a/PVE/Storage/DirPlugin.pm
+++ b/PVE/Storage/DirPlugin.pm
@@ -59,6 +59,7 @@ sub options {
 	mkdir => { optional => 1 },
 	is_mountpoint => { optional => 1 },
 	bwlimit => { optional => 1 },
+	preallocation => { optional => 1 },
    };
 }
 
diff --git a/PVE/Storage/GlusterfsPlugin.pm b/PVE/Storage/GlusterfsPlugin.pm
index ea4df82..d8d2b88 100644
--- a/PVE/Storage/GlusterfsPlugin.pm
+++ b/PVE/Storage/GlusterfsPlugin.pm
@@ -137,6 +137,7 @@ sub options {
 	format => { optional => 1 },
 	mkdir => { optional => 1 },
 	bwlimit => { optional => 1 },
+	preallocation => { optional => 1 },
     };
 }
 
@@ -260,7 +261,8 @@ sub alloc_image {
 
     my $cmd = ['/usr/bin/qemu-img', 'create'];
 
-    push @$cmd, '-o', 'preallocation=metadata' if $fmt eq 'qcow2';
+    my $prealloc_opt = PVE::Storage::Plugin::preallocation_cmd_option($scfg, $fmt);
+    push @$cmd, '-o', $prealloc_opt if defined($prealloc_opt);
 
     push @$cmd, '-f', $fmt, $volumepath, "${size}K";
 
diff --git a/PVE/Storage/NFSPlugin.pm b/PVE/Storage/NFSPlugin.pm
index 39bf15a..21b288a 100644
--- a/PVE/Storage/NFSPlugin.pm
+++ b/PVE/Storage/NFSPlugin.pm
@@ -90,6 +90,7 @@ sub options {
 	format => { optional => 1 },
 	mkdir => { optional => 1 },
 	bwlimit => { optional => 1 },
+	preallocation => { optional => 1 },
     };
 }
 
diff --git a/PVE/Storage/Plugin.pm b/PVE/Storage/Plugin.pm
index b1865cb..4924525 100644
--- a/PVE/Storage/Plugin.pm
+++ b/PVE/Storage/Plugin.pm
@@ -41,6 +41,19 @@ our @SHARED_STORAGE = (
     'pbs',
 );
 
+our $QCOW2_PREALLOCATION = {
+    off => 1,
+    metadata => 1,
+    falloc => 1,
+    full => 1,
+};
+
+our $RAW_PREALLOCATION = {
+    off => 1,
+    falloc => 1,
+    full => 1,
+};
+
 our $MAX_VOLUMES_PER_GUEST = 1024;
 
 cfs_register_file ('storage.cfg',
@@ -150,6 +163,11 @@ my $defaultData = {
 	    type => 'string', format => 'pve-storage-format',
 	    optional => 1,
 	},
+	preallocation => {
+	    description => "Preallocation mode for raw and qcow2 images.",
+	    type => 'string', enum => ['default', 'off', 'metadata', 'falloc', 'full'],
+	    optional => 1,
+	},
     },
 };
 
@@ -762,7 +780,8 @@ sub alloc_image {
     } else {
 	my $cmd = ['/usr/bin/qemu-img', 'create'];
 
-	push @$cmd, '-o', 'preallocation=metadata' if $fmt eq 'qcow2';
+	my $prealloc_opt = preallocation_cmd_option($scfg, $fmt);
+	push @$cmd, '-o', $prealloc_opt if defined($prealloc_opt);
 
 	push @$cmd, '-f', $fmt, $path, "${size}K";
 
@@ -1484,4 +1503,29 @@ sub volume_import_formats {
     return ();
 }
 
+sub preallocation_cmd_option {
+    my ($scfg, $fmt) = @_;
+
+    my $prealloc = $scfg->{preallocation};
+
+    $prealloc = undef if $prealloc eq 'default';
+
+    if ($fmt eq 'qcow2') {
+	$prealloc = $prealloc // 'metadata';
+
+	die "preallocation mode '$prealloc' not supported by format '$fmt'\n" if !$QCOW2_PREALLOCATION->{$prealloc};
+
+	return "preallocation=$prealloc";
+    } elsif ($fmt eq 'raw') {
+	$prealloc = $prealloc // 'off';
+	$prealloc = 'off' if $prealloc eq 'metadata';
+
+	die "preallocation mode '$prealloc' not supported by format '$fmt'\n" if !$RAW_PREALLOCATION->{$prealloc};
+
+	return "preallocation=$prealloc";
+    }
+
+    return undef;
+}
+
 1;
-- 
2.30.2