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marsadm: fix race on system lock breaks

This commit is contained in:
Thomas Schoebel-Theuer 2020-11-13 15:04:40 +01:00
parent c27441325d
commit 3fa0421365
1 changed files with 41 additions and 20 deletions
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61
userspace/marsadm
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@ -907,6 +907,7 @@ my @systemctl_enable =
);
my %recursive_locks;
my $lock_fh;
sub systemd_lock {
my ($suffix, $try_lock) = @_;
@ -921,15 +922,35 @@ sub systemd_lock {
use Fcntl;
my $max_time = $timeout > 0 ? $timeout : 30;
my $count = 0;
my $retry = 0;
my $fh;
retry:
for (;;) {
my $test_pid;
my $test_pid = 1;
if (open(my $IN, "<", $lock_file)) {
$test_pid = <$IN>;
chomp $test_pid;
my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
$atime,$mtime,$ctime,$blksize,$blocks) = stat($IN);
my $pid_exists = 0;
my @pid_list = ();
while ($test_pid = <$IN>) {
chomp $test_pid;
next unless $test_pid;
if (-d "/proc/$test_pid") {
$pid_exists++;
} else {
push @pid_list, $test_pid;
}
}
if (!$pid_exists) {
# race prevention: wait until situation is stable
if ($count-- >= -3) {
sleep(1);
goto retry;
}
unlink($lock_file);
lwarn "breaking lock $lock_file, pids {" .
join(",", @pid_list) .
"} are no longer alive.\n";
$count = 0;
goto retry;
}
my $mtime = get_stamp($IN);
close($IN);
# Check for timeout
if ($count > $max_time ||
@ -939,18 +960,9 @@ sub systemd_lock {
$count = 0;
}
}
$fh = undef;
my $status = sysopen($fh, $lock_file, O_CREAT|O_EXCL|O_TRUNC|O_WRONLY);
$lock_fh = undef;
my $status = sysopen($lock_fh, $lock_file, O_CREAT|O_EXCL|O_TRUNC|O_WRONLY);
last if defined($status) && $status;
# Check whether pid exists
if (defined($test_pid) && $test_pid && ! -d "/proc/$test_pid") {
next if !$retry++;
lwarn "breaking lock $lock_file, pid $test_pid is no longer alive.\n";
unlink($lock_file);
$count = 0;
$retry = 0;
next;
}
if (defined($try_lock) && $try_lock && !$force) {
lprint "FAILED '$lock_file'\n" if $verbose > 1;
return 1;
@ -958,14 +970,16 @@ sub systemd_lock {
$count++;
sleep(1);
}
print $fh "$$\n";
close($fh);
print $lock_fh "$$\n";
$lock_fh->flush();
lprint "LOCK '$lock_file'\n" if $verbose > 1;
return 0;
}
sub systemd_unlock {
my ($suffix) = @_;
close($lock_fh) if defined($lock_fh);
$lock_fh = undef;
my $lock_file = $systemd_lock_file;
$lock_file .= "." . $suffix if defined($suffix) && $suffix;
if (--$recursive_locks{$lock_file} > 0) {
@ -1765,6 +1779,13 @@ sub get_link_stamp {
return $stat[9];
}
sub get_stamp {
my ($path_or_handle) = @_;
my @stat = stat($path_or_handle);
return 0 if (!@stat);
return $stat[9];
}
sub is_recent {
my ($stamp, $wind) = @_;
return 0 unless ($stamp && $stamp =~ m/^\s*[0-9.]/);