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From: Stoiko Ivanov <s.ivanov@proxmox.com>
To: pve-devel@lists.proxmox.com
Date: Fri, 6 Nov 2020 15:19:41 +0100
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Subject: [pve-devel] [PATCH container v3 1/2] add fsfreeze helper:
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fsfreeze_mountpoint issues the same ioctls as fsfreeze(8) on the provided
directory (the $thaw parameter deciding between '--freeze' and '--unfreeze')
This is used for container backups on RBD, where snapshots on containers,
which are heavy on IO, are not mountable readonly, because the ext4 is not
consistent.
Needed to fix #2991 and #2528.
The ioctl numbers were found via strace -X verbose (and verified with the
kernel documentation).
Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
---
src/PVE/LXC/Config.pm | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/src/PVE/LXC/Config.pm b/src/PVE/LXC/Config.pm
index 49f599b..0528d51 100644
--- a/src/PVE/LXC/Config.pm
+++ b/src/PVE/LXC/Config.pm
@@ -13,6 +13,9 @@ use PVE::Tools;
use base qw(PVE::AbstractConfig);
+use constant {FIFREEZE => 0xc0045877,
+ FITHAW => 0xc0045878};
+
my $nodename = PVE::INotify::nodename();
my $lock_handles = {};
my $lockdir = "/run/lock/lxc";
@@ -109,6 +112,22 @@ sub __snapshot_check_freeze_needed {
return ($ret, $ret);
}
+# implements similar functionality to fsfreeze(8)
+sub fsfreeze_mountpoint {
+ my ($path, $thaw) = @_;
+
+ my $op = $thaw ? 'thaw' : 'freeze';
+ my $ioctl = $thaw ? FITHAW : FIFREEZE;
+
+ sysopen my $fd, $path, O_RDONLY or die "failed to open $path: $!\n";
+ my $ioctl_err;
+ if (!ioctl($fd, $ioctl, 0)) {
+ $ioctl_err = "$!";
+ }
+ close($fd);
+ die "fs$op '$path' failed - $ioctl_err\n" if defined $ioctl_err;
+}
+
sub __snapshot_freeze {
my ($class, $vmid, $unfreeze) = @_;
--
2.20.1