rewrite Linux nodatacow use in pure Perl w/o system

[public-inbox.git] / lib / PublicInbox / Syscall.pm

diff --git a/lib/PublicInbox/Syscall.pm b/lib/PublicInbox/Syscall.pm
index c00385b94db84b63facf7a8d57296ac76b3b1421..bcfae2cbcae423ef70171c90f3e52be3932c00ad 100644 (file)
--- a/lib/PublicInbox/Syscall.pm
+++ b/lib/PublicInbox/Syscall.pm
@@ -5,7 +5,7 @@
 # This license differs from the rest of public-inbox
 #
 # This module is Copyright (c) 2005 Six Apart, Ltd.
-# Copyright (C) 2019-2021 all contributors <meta@public-inbox.org>
+# Copyright (C) all contributors <meta@public-inbox.org>
 #
 # All rights reserved.
 #
@@ -68,6 +68,7 @@ our (
      $SYS_renameat2,
      );
 
+my $SYS_fstatfs; # don't need fstatfs64, just statfs.f_type
 my $SFD_CLOEXEC = 02000000; # Perl does not expose O_CLOEXEC
 our $no_deprecated = 0;
 
@@ -96,18 +97,21 @@ if ($^O eq "linux") {
         $SYS_epoll_wait   = 256;
         $SYS_signalfd4 = 327;
         $SYS_renameat2 //= 353;
+       $SYS_fstatfs = 100;
     } elsif ($machine eq "x86_64") {
         $SYS_epoll_create = 213;
         $SYS_epoll_ctl    = 233;
         $SYS_epoll_wait   = 232;
         $SYS_signalfd4 = 289;
        $SYS_renameat2 //= 316;
+       $SYS_fstatfs = 138;
     } elsif ($machine eq 'x32') {
         $SYS_epoll_create = 1073742037;
         $SYS_epoll_ctl = 1073742057;
         $SYS_epoll_wait = 1073742056;
         $SYS_signalfd4 = 1073742113;
        $SYS_renameat2 //= 0x40000000 + 316;
+       $SYS_fstatfs = 138;
     } elsif ($machine eq 'sparc64') {
        $SYS_epoll_create = 193;
        $SYS_epoll_ctl = 194;
@@ -116,6 +120,7 @@ if ($^O eq "linux") {
        $SYS_signalfd4 = 317;
        $SYS_renameat2 //= 345;
        $SFD_CLOEXEC = 020000000;
+       $SYS_fstatfs = 158;
     } elsif ($machine =~ m/^parisc/) {
         $SYS_epoll_create = 224;
         $SYS_epoll_ctl    = 225;
@@ -129,6 +134,7 @@ if ($^O eq "linux") {
         $u64_mod_8        = 1;
         $SYS_signalfd4 = 313;
        $SYS_renameat2 //= 357;
+       $SYS_fstatfs = 100;
     } elsif ($machine eq "ppc") {
         $SYS_epoll_create = 236;
         $SYS_epoll_ctl    = 237;
@@ -136,6 +142,7 @@ if ($^O eq "linux") {
         $u64_mod_8        = 1;
         $SYS_signalfd4 = 313;
        $SYS_renameat2 //= 357;
+       $SYS_fstatfs = 100;
     } elsif ($machine =~ m/^s390/) {
         $SYS_epoll_create = 249;
         $SYS_epoll_ctl    = 250;
@@ -143,6 +150,7 @@ if ($^O eq "linux") {
         $u64_mod_8        = 1;
         $SYS_signalfd4 = 322;
        $SYS_renameat2 //= 347;
+       $SYS_fstatfs = 100;
     } elsif ($machine eq "ia64") {
         $SYS_epoll_create = 1243;
         $SYS_epoll_ctl    = 1244;
@@ -165,6 +173,7 @@ if ($^O eq "linux") {
         $no_deprecated    = 1;
         $SYS_signalfd4 = 74;
        $SYS_renameat2 //= 276;
+       $SYS_fstatfs = 44;
     } elsif ($machine =~ m/arm(v\d+)?.*l/) {
         # ARM OABI
         $SYS_epoll_create = 250;
@@ -173,6 +182,7 @@ if ($^O eq "linux") {
         $u64_mod_8        = 1;
         $SYS_signalfd4 = 355;
        $SYS_renameat2 //= 382;
+       $SYS_fstatfs = 100;
     } elsif ($machine =~ m/^mips64/) {
         $SYS_epoll_create = 5207;
         $SYS_epoll_ctl    = 5208;
@@ -180,6 +190,7 @@ if ($^O eq "linux") {
         $u64_mod_8        = 1;
         $SYS_signalfd4 = 5283;
        $SYS_renameat2 //= 5311;
+       $SYS_fstatfs = 5135;
     } elsif ($machine =~ m/^mips/) {
         $SYS_epoll_create = 4248;
         $SYS_epoll_ctl    = 4249;
@@ -187,6 +198,7 @@ if ($^O eq "linux") {
         $u64_mod_8        = 1;
         $SYS_signalfd4 = 4324;
        $SYS_renameat2 //= 4351;
+       $SYS_fstatfs = 4100;
     } else {
         # as a last resort, try using the *.ph files which may not
         # exist or may be wrong
@@ -323,6 +335,38 @@ sub rename_noreplace ($$) {
        }
 }
 
+sub nodatacow_fh {
+       return if !defined($SYS_fstatfs);
+       my $buf = '';
+       vec($buf, 120 * 8 - 1, 1) = 0;
+       my ($fh) = @_;
+       syscall($SYS_fstatfs, fileno($fh), $buf) == 0 or
+               return warn("fstatfs: $!\n");
+       my $f_type = unpack('l!', $buf); # statfs.f_type is a signed word
+       return if $f_type != 0x9123683E; # BTRFS_SUPER_MAGIC
+
+       state ($FS_IOC_GETFLAGS, $FS_IOC_SETFLAGS);
+       unless (defined $FS_IOC_GETFLAGS) {
+               if (substr($Config{byteorder}, 0, 4) eq '1234') {
+                       $FS_IOC_GETFLAGS = 0x80086601;
+                       $FS_IOC_SETFLAGS = 0x40086602;
+               } else { # Big endian
+                       $FS_IOC_GETFLAGS = 0x40086601;
+                       $FS_IOC_SETFLAGS = 0x80086602;
+               }
+       }
+       ioctl($fh, $FS_IOC_GETFLAGS, $buf) //
+               return warn("FS_IOC_GET_FLAGS: $!\n");
+       my $attr = unpack('l!', $buf);
+       return if ($attr & 0x00800000); # FS_NOCOW_FL;
+       ioctl($fh, $FS_IOC_SETFLAGS, pack('l', $attr | 0x00800000)) //
+               warn("FS_IOC_SET_FLAGS: $!\n");
+}
+
+sub nodatacow_dir {
+       if (open my $fh, '<', $_[0]) { nodatacow_fh($fh) }
+}
+
 1;
 
 =head1 WARRANTY