[gparted] Don't limit ext4 volume size when 64bit feature is available (#766910)

[Curtis Gedak <gedakc src gnome org>]

commit a13526bf4102bd18019cab83abf0c3b83b9fb232
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Fri Jun 3 22:23:25 2016 +0100

    Don't limit ext4 volume size when 64bit feature is available (#766910)
    
    E2fsprogs 1.42 adds ext4 64bit feature [1] allowing volume sizes larger
    than 16 TiB.  However only enable large volumes from e2fsprogs 1.42.9
    when a large number of 64bit bugs were fixed [2].  (Also RHEL / CentOS 7
    use e2fsprogs 1.42.9 and always enable 64bit feature by default).
    
    [1] Release notes, E2fsprogs 1.42 (November 29, 2011)
        http://e2fsprogs.sourceforge.net/e2fsprogs-release.html#1.42
    
        "This release of e2fsprogs has support for file systems > 16TB.
        Online resize requires kernel support which will hopefully be in
        Linux version 3.2.  Offline support is not yet available for > 16TB
        file systems, but will be coming".
    
    [2] Release notes, E2fsprogs 1.42.9 (December 28, 2013)
        http://e2fsprogs.sourceforge.net/e2fsprogs-release.html#1.42.9
    
        "Fixed a large number of bugs in resize2fs, e2fsck, debugfs, and
        libext2fs to correctly handle bigalloc and 64-bit file systems.
        There were many corner cases that had not been noticed in previous
        uses of these file systems, since they are not as common.  Some of
        the bugs could cause file system corruption or data loss, so users
        of 64-bit or bigalloc file systems are strongly urged to upgrade to
        e2fsprogs 1.42.9".
    
    Bug 766910 - Multiple boot loaders don't work on 64bit EXT4 file systems

 src/ext2.cc |   31 +++++++++++++++++++++++++++++--
 1 files changed, 29 insertions(+), 2 deletions(-)
---
diff --git a/src/ext2.cc b/src/ext2.cc
index 8952e48..0d4486e 100644
--- a/src/ext2.cc
+++ b/src/ext2.cc
@@ -43,6 +43,30 @@ FS ext2::get_filesystem_support()
                fs .create = FS::EXTERNAL ;
                fs .create_with_label = FS::EXTERNAL ;
 
+               // Determine availability of ext4 64bit feature
+               bool have_64bit_feature = false;
+               if ( specific_type == FS_EXT4 )
+               {
+                       Utils::execute_command( mkfs_cmd + " -V", output, error, true );
+                       int mke4fs_major_ver = 0;
+                       int mke4fs_minor_ver = 0;
+                       int mke4fs_patch_ver = 0;
+                       if ( sscanf( error.c_str(), "mke2fs %d.%d.%d",
+                                    &mke4fs_major_ver, &mke4fs_minor_ver, &mke4fs_patch_ver ) >= 2 )
+                       {
+                               // Ext4 64bit feature was added in e2fsprogs 1.42, but
+                               // only enable large volumes from 1.42.9 when a large
+                               // number of 64bit bugs were fixed.
+                               // *   Release notes, E2fsprogs 1.42 (November 29, 2011)
+                               //     http://e2fsprogs.sourceforge.net/e2fsprogs-release.html#1.42
+                               // *   Release notes, E2fsprogs 1.42.9 (December 28, 2013)
+                               //     http://e2fsprogs.sourceforge.net/e2fsprogs-release.html#1.42.9
+                               have_64bit_feature =    ( mke4fs_major_ver > 1 )
+                                                    || ( mke4fs_major_ver == 1 && mke4fs_minor_ver > 42 )
+                                                    || ( mke4fs_major_ver == 1 && mke4fs_minor_ver == 42 && 
mke4fs_patch_ver >= 9 );
+                       }
+               }
+
                if ( specific_type == FS_EXT4 && ! Glib::find_program_in_path( "dumpe4fs" ).empty() )
                        dump_cmd = "dumpe4fs";
                else if ( ! Glib::find_program_in_path( "dumpe2fs" ).empty() )
@@ -115,7 +139,7 @@ FS ext2::get_filesystem_support()
                        fs .online_grow = fs .grow ;
 #endif
 
-               // Maximum size of an ext2/3/4 volume is 2^32 - 1 blocks, ignoring ext4
+               // Maximum size of an ext2/3/4 volume is 2^32 - 1 blocks, except for ext4
                // with 64bit feature.  That is just under 16 TiB with a 4K block size.
                // *   Ext4 Disk Layout, Blocks
                //     https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout#Blocks
@@ -123,7 +147,10 @@ FS ext2::get_filesystem_support()
                // Copy, New and Resize/Move dialogs should limit FS correctly without
                // this.  See bug #766910 comment #12 onwards for further discussion.
                //     https://bugzilla.gnome.org/show_bug.cgi?id=766910#c12
-               fs.MAX = Utils::floor_size( 16 * TEBIBYTE - 4 * KIBIBYTE, MEBIBYTE );
+               if ( specific_type == FS_EXT2                             ||
+                    specific_type == FS_EXT3                             ||
+                    ( specific_type == FS_EXT4 && ! have_64bit_feature )    )
+                       fs.MAX = Utils::floor_size( 16 * TEBIBYTE - 4 * KIBIBYTE, MEBIBYTE );
        }
 
        return fs ;