[gparted/new-master] Fix false usage figures for busy SWRAID members (#27)

[Mike Fleetwood <mfleetwo src gnome org>]

commit 79770640c1c2df64d9c8c4018f0c529bfc3f47c9
Author: Mike Fleetwood <mike fleetwood googlemail com>
Date:   Sun Nov 18 12:41:56 2018 +0000

    Fix false usage figures for busy SWRAID members (#27)
    
    Create an active Linux Software RAID member which is larger than /dev
    virtual file system and GParted will report the usage figure of the /dev
    virtual file system for the SWRAID member.
    
        # df -h /dev
        Filesystem      Size  Used Avail Use% Mounted on
        devtmpfs        732M     0  732M   0% /dev
        # sgdisk -n 1:1M:+1G /dev/sdb
        # mdadm --create --verbose /dev/md1 --level=linear --raid-devices=1 --force /dev/sdb1
        mdadm: Defaulting to version 1.2 metadata
        mdadm: array /dev/md1 started.
    
    GParted reports the usage of /dev/sdb1 as:
        Partition  Mount Point  Size     Used   Unused     Unallocated
        /dev/sdb1  /dev/md1     1.00GiB  0.00B  731.04MiB  292.96MiB
    
    However GParted should have reported the usage as "---" for unknown
    because it isn't coded to query the size of the SWRAID member within a
    partition.
    
    The fault has been bisected to this commit:
        Extend un/mounting and usage reporting to unsupported file systems (!13)
        95903efb1f284f3d6819f38e894dc6c3464b2183
    
    What happens for busy Linux Software RAID array members:
    *   GParted_Core::is_busy()
        has custom code to identify busy members.
    *   GParted_Core::set_mountpoints()
        has custom code to add the array device name as the "mount point" of
        the member.
    *   GParted_Core::set_used_sectors()
        falls into the else not a supported file system (because SWRAID
        doesn't have a derived FileSystem implementation class).
    *   GParted_Core::mounted_set_used_sectors()
        is called to get the file system usage of mounted, but unsupported
        file systems, such as UFS and any others.
    *   Utils::get_mounted_filesystem_usage()
        is called which queries the kernel using statvfs() and gets the file
        system usage of the /dev virtual file system because the array
        device name will always start /dev.
    
    Fix by ensuring that GParted only asks the kernel for the usage of paths
    which it knows are mount points of mounted file systems.  (As read from
    /proc/mounts and cached in the Mount_Info module).  Also rename the
    method, by inserting "_fs", to mounted_fs_set_used_sectors() to remind
    us that it is for mounted *file systems* only.
    
    Closes #27 - GParted may report incorrect usage for SWRAID partitions
                 instead of unknown

 include/GParted_Core.h |  2 +-
 src/GParted_Core.cc    | 10 +++++-----
 2 files changed, 6 insertions(+), 6 deletions(-)
---
diff --git a/include/GParted_Core.h b/include/GParted_Core.h
index 94d204b5..c0b81445 100644
--- a/include/GParted_Core.h
+++ b/include/GParted_Core.h
@@ -96,7 +96,7 @@ private:
        bool set_mountpoints_helper( Partition & partition, const Glib::ustring & path );
        bool is_busy( FSType fstype, const Glib::ustring & path );
        void set_used_sectors( Partition & partition, PedDisk* lp_disk );
-       void mounted_set_used_sectors( Partition & partition ) ;
+       void mounted_fs_set_used_sectors(Partition& partition);
 #ifdef HAVE_LIBPARTED_FS_RESIZE
        void LP_set_used_sectors( Partition & partition, PedDisk* lp_disk ) ;
 #endif
diff --git a/src/GParted_Core.cc b/src/GParted_Core.cc
index a79cda9c..8528a604 100644
--- a/src/GParted_Core.cc
+++ b/src/GParted_Core.cc
@@ -1748,7 +1748,7 @@ void GParted_Core::set_used_sectors( Partition & partition, PedDisk* lp_disk )
                                                p_filesystem->set_used_sectors( partition );
                                        break;
                                case FS::GPARTED:
-                                       mounted_set_used_sectors( partition );
+                                       mounted_fs_set_used_sectors( partition );
                                        break;
                                default:
                                        break;
@@ -1830,15 +1830,15 @@ void GParted_Core::set_used_sectors( Partition & partition, PedDisk* lp_disk )
        }
        else
        {
-               // Set usage of mouted but unsupported file systems
+               // Set usage of mounted but unsupported file systems.
                if ( partition.busy )
-                       mounted_set_used_sectors( partition );
+                       mounted_fs_set_used_sectors(partition);
        }
 }
 
-void GParted_Core::mounted_set_used_sectors( Partition & partition )
+void GParted_Core::mounted_fs_set_used_sectors( Partition & partition )
 {
-       if ( partition .get_mountpoints() .size() > 0 )
+       if (partition.get_mountpoints().size() > 0 && Mount_Info::is_dev_mounted(partition.get_path()))
        {
                Byte_Value fs_size ;
                Byte_Value fs_free ;