[pve-devel] [PATCH container 2/2] api: resize: fork before locking

[Fiona Ebner <f.ebner@proxmox.com>]

making sure the early checks are done once before the expensive
forking and locking and once after locking, because the state might
have changed.

The size calculation had to be adapted a bit, to ensure the original
size is not added twice when it's a request with a leading '+'.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---

Best viewed with -w.

 src/PVE/API2/LXC.pm | 124 +++++++++++++++++++++++---------------------
 1 file changed, 66 insertions(+), 58 deletions(-)

diff --git a/src/PVE/API2/LXC.pm b/src/PVE/API2/LXC.pm
index f69b44b..2d67997 100644
--- a/src/PVE/API2/LXC.pm
+++ b/src/PVE/API2/LXC.pm
@@ -1926,15 +1926,14 @@ __PACKAGE__->register_method({
 
 	my $sizestr = extract_param($param, 'size');
 	my $ext = ($sizestr =~ s/^\+//);
-	my $newsize = PVE::JSONSchema::parse_size($sizestr);
-	die "invalid size string" if !defined($newsize);
+	my $request_size = PVE::JSONSchema::parse_size($sizestr);
+	die "invalid size string" if !defined($request_size);
 
 	die "no options specified\n" if !scalar(keys %$param);
 
 	my $storage_cfg = cfs_read_file("storage.cfg");
 
-	my $code = sub {
-
+	my $load_and_check = sub {
 	    my $conf = PVE::LXC::Config->load_config($vmid);
 	    PVE::LXC::Config->check_lock($conf);
 
@@ -1942,8 +1941,6 @@ __PACKAGE__->register_method({
 
 	    PVE::Tools::assert_if_modified($digest, $conf->{digest});
 
-	    my $running = PVE::LXC::check_running($vmid);
-
 	    my $disk = $param->{disk};
 	    my $mp = PVE::LXC::Config->parse_volume($disk, $conf->{$disk});
 
@@ -1965,66 +1962,77 @@ __PACKAGE__->register_method({
 
 	    die "Could not determine current size of volume '$volid'\n" if !defined($size);
 
-	    $newsize += $size if $ext;
+	    my $newsize = $ext ? $size + $request_size : $request_size;
 	    $newsize = int($newsize);
 
 	    die "unable to shrink disk size\n" if $newsize < $size;
 
 	    die "disk is already at specified size\n" if $size == $newsize;
 
-	    PVE::Cluster::log_msg('info', $authuser, "update CT $vmid: resize --disk $disk --size $sizestr");
-	    my $realcmd = sub {
-		# Note: PVE::Storage::volume_resize doesn't do anything if $running=1, so
-		# we pass 0 here (parameter only makes sense for qemu)
-		PVE::Storage::volume_resize($storage_cfg, $volid, $newsize, 0);
-
-		$mp->{size} = $newsize;
-		$conf->{$disk} = PVE::LXC::Config->print_ct_mountpoint($mp, $disk eq 'rootfs');
-
-		PVE::LXC::Config->write_config($vmid, $conf);
-
-		if ($format eq 'raw') {
-		    # we need to ensure that the volume is mapped, if not needed this is a NOP
-		    my $path = PVE::Storage::map_volume($storage_cfg, $volid);
-		    $path = PVE::Storage::path($storage_cfg, $volid) if !defined($path);
-		    if ($running) {
-
-			$mp->{mp} = '/';
-			my $use_loopdev = (PVE::LXC::mountpoint_mount_path($mp, $storage_cfg))[1];
-			$path = PVE::LXC::query_loopdev($path) if $use_loopdev;
-			die "internal error: CT running but mount point not attached to a loop device"
-			    if !$path;
-			PVE::Tools::run_command(['losetup', '--set-capacity', $path]) if $use_loopdev;
-
-			# In order for resize2fs to know that we need online-resizing a mountpoint needs
-			# to be visible to it in its namespace.
-			# To not interfere with the rest of the system we unshare the current mount namespace,
-			# mount over /tmp and then run resize2fs.
-
-			# interestingly we don't need to e2fsck on mounted systems...
-			my $quoted = PVE::Tools::shellquote($path);
-			my $cmd = "mount --make-rprivate / && mount $quoted /tmp && resize2fs $quoted";
-			eval {
-			    PVE::Tools::run_command(['unshare', '-m', '--', 'sh', '-c', $cmd]);
-			};
-			warn "Failed to update the container's filesystem: $@\n" if $@;
-		    } else {
-			eval {
-			    PVE::Tools::run_command(['e2fsck', '-f', '-y', $path]);
-			    PVE::Tools::run_command(['resize2fs', $path]);
-			};
-			warn "Failed to update the container's filesystem: $@\n" if $@;
-
-			# always un-map if not running, this is a NOP if not needed
-			PVE::Storage::unmap_volume($storage_cfg, $volid);
-		    }
-		}
-	    };
-
-	    return $rpcenv->fork_worker('resize', $vmid, $authuser, $realcmd);
+	    return ($conf, $disk, $mp, $volid, $format, $newsize);
 	};
 
-	return PVE::LXC::Config->lock_config($vmid, $code);;
+	my $code = sub {
+	    my ($conf, $disk, $mp, $volid, $format, $newsize) = $load_and_check->();
+
+	    my $running = PVE::LXC::check_running($vmid);
+
+	    PVE::Cluster::log_msg('info', $authuser, "update CT $vmid: resize --disk $disk --size $sizestr");
+
+	    # Note: PVE::Storage::volume_resize doesn't do anything if $running=1, so
+	    # we pass 0 here (parameter only makes sense for qemu)
+	    PVE::Storage::volume_resize($storage_cfg, $volid, $newsize, 0);
+
+	    $mp->{size} = $newsize;
+	    $conf->{$disk} = PVE::LXC::Config->print_ct_mountpoint($mp, $disk eq 'rootfs');
+
+	    PVE::LXC::Config->write_config($vmid, $conf);
+
+	    if ($format eq 'raw') {
+		# we need to ensure that the volume is mapped, if not needed this is a NOP
+		my $path = PVE::Storage::map_volume($storage_cfg, $volid);
+		$path = PVE::Storage::path($storage_cfg, $volid) if !defined($path);
+		if ($running) {
+
+		    $mp->{mp} = '/';
+		    my $use_loopdev = (PVE::LXC::mountpoint_mount_path($mp, $storage_cfg))[1];
+		    $path = PVE::LXC::query_loopdev($path) if $use_loopdev;
+		    die "internal error: CT running but mount point not attached to a loop device"
+			if !$path;
+		    PVE::Tools::run_command(['losetup', '--set-capacity', $path]) if $use_loopdev;
+
+		    # In order for resize2fs to know that we need online-resizing a mountpoint needs
+		    # to be visible to it in its namespace.
+		    # To not interfere with the rest of the system we unshare the current mount namespace,
+		    # mount over /tmp and then run resize2fs.
+
+		    # interestingly we don't need to e2fsck on mounted systems...
+		    my $quoted = PVE::Tools::shellquote($path);
+		    my $cmd = "mount --make-rprivate / && mount $quoted /tmp && resize2fs $quoted";
+		    eval {
+			PVE::Tools::run_command(['unshare', '-m', '--', 'sh', '-c', $cmd]);
+		    };
+		    warn "Failed to update the container's filesystem: $@\n" if $@;
+		} else {
+		    eval {
+			PVE::Tools::run_command(['e2fsck', '-f', '-y', $path]);
+			PVE::Tools::run_command(['resize2fs', $path]);
+		    };
+		    warn "Failed to update the container's filesystem: $@\n" if $@;
+
+		    # always un-map if not running, this is a NOP if not needed
+		    PVE::Storage::unmap_volume($storage_cfg, $volid);
+		}
+	    }
+	};
+
+	my $worker = sub {
+	    PVE::LXC::Config->lock_config($vmid, $code);;
+	};
+
+	$load_and_check->(); # early checks before forking+locking
+
+	return $rpcenv->fork_worker('resize', $vmid, $authuser, $worker);
     }});
 
 __PACKAGE__->register_method({
-- 
2.39.2