From: Stoiko Ivanov <s.ivanov@proxmox.com>
Date: Thu, 17 Jan 2019 15:31:51 +0000 (+0100)
Subject: Fix #2050: only provide 'conv=sparse' for LvmThin
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=4e8de9ad561b343dd4dbe7827603e68188bf99cb;p=pve-storage.git

Fix #2050: only provide 'conv=sparse' for LvmThin

LVMPlugin->volume_import (used by storage_migrate on either offline
migration with local disks, or online migration with storage-only
referenced disks) passed 'conv=sparse' to `dd`. This can lead to
data-corruption, if the target volume is not zero-initialized.

dropping the sparse argument completely would fix the problem, but
breaks keeping data sparse for LvmThinPlugin.

This patch moves the dd out into (LVM*) plugin specific sub so that
each can control the parameters.

Steps for reproducing the issue:
* create a cluster with (at least) 2 nodes A and B, with a free
  disk-device (/dev/sdx)
* write a recognizable pattern to /dev/sdx on B:
  `dd if=/dev/zero bs=10M | tr '\000' '\255' | dd of=/dev/sdb bs=10M`
  (would be grateful for alternatives to the dd| tr| dd)
* on both A and B create a lvm-vg (pvcreate, vgcreate)
* add it as _not_ shared storage, which is available on nodes A and B
* create a small guest on A
* fill a file in the guest with zeros
  `dd if=/dev/zero of=/zerofil bs=10M`
* stop the guest, migrate it to B
* start the guest - check that the file `/zerofil` contains `ad`
  instead of `00`

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---

diff --git a/PVE/Storage/LVMPlugin.pm b/PVE/Storage/LVMPlugin.pm
index 72d7464..9ad7979 100644
--- a/PVE/Storage/LVMPlugin.pm
+++ b/PVE/Storage/LVMPlugin.pm
@@ -620,8 +620,8 @@ sub volume_import {
 	}
 	my $file = $class->path($scfg, $volname, $storeid)
 	    or die "internal error: failed to get path to newly allocated volume $volname\n";
-	run_command(['dd', "of=$file", 'conv=sparse', 'bs=64k'],
-	            input => '<&'.fileno($fh));
+
+	$class->volume_import_write($fh, $file);
     };
     if (my $err = $@) {
 	eval { $class->free_image($storeid, $scfg, $volname, 0) };
@@ -630,4 +630,10 @@ sub volume_import {
     }
 }
 
+sub volume_import_write {
+    my ($class, $input_fh, $output_file) = @_;
+    run_command(['dd', "of=$output_file", 'bs=64k'],
+	input => '<&'.fileno($input_fh));
+}
+
 1;
diff --git a/PVE/Storage/LvmThinPlugin.pm b/PVE/Storage/LvmThinPlugin.pm
index 122fb37..aafc202 100644
--- a/PVE/Storage/LvmThinPlugin.pm
+++ b/PVE/Storage/LvmThinPlugin.pm
@@ -374,4 +374,11 @@ sub volume_has_feature {
     return undef;
 }
 
+# used in LVMPlugin->volume_import
+sub volume_import_write {
+    my ($class, $input_fh, $output_file) = @_;
+    run_command(['dd', "of=$output_file", 'conv=sparse', 'bs=64k'],
+	input => '<&'.fileno($input_fh));
+}
+
 1;