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Read file system size for mounted ext2/3/4 from superblock (#683255) 

A user had a 190 MiB partition containing an old ext2 file system.  When
unmounted it was reported as filling the partition, but when mounted it
was reported as having 6% unallocated space.  The file system's inode
tables were approximately twice the size of those created by default
with the current mkfs.ext2 defaults.

To create an equivalent file system in a 190 MiB partition:
    mkfs.ext2 -N 97344 /dev/sda15

It turns out that for ext2, ext3 and ext4 file systems what was
described as intrinsic unallocated space during the development of
Bug #499202 is actually file system overhead.  When mounted the ext2/3/4
kernel code reports the size of the file system after subtracting the
overhead.  Overhead is made up of superblock backups, group descriptors,
allocation bitmaps and largest of all inode tables.  E2fsprogs tools
don't subtract this overhead when reporting the file system size.

References:

 *  The Second Extended File System, Internal Layout, by Dave Poirier
    http://www.nongnu.org/ext2-doc/ext2.html

 *  Linux ext2_statfs() function
    http://lxr.linux.no/#linux+v3.5.3/fs/ext2/super.c#L1311

Call the file system specific method for reading the usage of ext2, ext3
and ext4 file systems while mounted.  Make it read the file system size
from the on disk superblock to avoid subtraction of overhead and use the
statvfs() system call to return an up to date free space figure.

Bug #683255 - ext2: statvfs differs from dumpe2fs (x MB unallocated
              space within the partition)
This commit is contained in:
Mike Fleetwood 2012-09-12 23:51:49 +01:00 committed by Curtis Gedak
parent 01150758c3
commit 3828019030
6 changed files with 132 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/Utils.h
View File

@ -188,6 +188,9 @@ public:
const Glib::ustring& delimiters ) ;
static int convert_to_int(const Glib::ustring & src);
static Glib::ustring generate_uuid(void);
static int get_mounted_filesystem_usage( const Glib::ustring & mountpoint,
Byte_Value & fs_size, Byte_Value & fs_free,
Glib::ustring error_message ) ;
private:
static bool get_kernel_version( int & major_ver, int & minor_ver, int & patch_ver ) ;

19
src/GParted_Core.cc
View File

@ -52,7 +52,6 @@
#include <set>
#include <cerrno>
#include <cstring>
#include <sys/statvfs.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
@ -1597,19 +1596,17 @@ void GParted_Core::set_used_sectors( std::vector<Partition> & partitions )
void GParted_Core::mounted_set_used_sectors( Partition & partition )
{
struct statvfs sfs ;
if ( partition .get_mountpoints() .size() > 0 )
{
if ( statvfs( partition .get_mountpoint() .c_str(), &sfs ) == 0 )
{
Sector fs_size = static_cast<Sector>( sfs .f_blocks ) * sfs .f_frsize / partition .sector_size ;
Sector fs_free = static_cast<Sector>( sfs .f_bfree ) * sfs .f_bsize / partition .sector_size ;
partition .set_sector_usage( fs_size, fs_free ) ;
}
Byte_Value fs_size ;
Byte_Value fs_free ;
Glib::ustring error_message ;
if ( Utils::get_mounted_filesystem_usage( partition .get_mountpoint(),
fs_size, fs_free, error_message ) == 0 )
partition .set_sector_usage( fs_size / partition .sector_size,
fs_free / partition .sector_size ) ;
else
partition .messages .push_back( "statvfs (" + partition .get_mountpoint() + "): " +
Glib::strerror( errno ) ) ;
partition .messages .push_back( error_message ) ;
}
}

22
src/Utils.cc
View File

@ -24,6 +24,8 @@
#include <glibmm/regex.h>
#include <locale.h>
#include <uuid/uuid.h>
#include <cerrno>
#include <sys/statvfs.h>
namespace GParted
@ -606,6 +608,26 @@ Glib::ustring Utils::generate_uuid(void)
return uuid_str;
}
//Wrapper around statvfs() system call to get mounted file system size
// and free space, both in bytes.
int Utils::get_mounted_filesystem_usage( const Glib::ustring & mountpoint,
Byte_Value & fs_size, Byte_Value & fs_free,
Glib::ustring error_message )
{
struct statvfs sfs ;
int ret ;
ret = statvfs( mountpoint .c_str(), &sfs ) ;
if ( ret == 0 )
{
fs_size = static_cast<Byte_Value>( sfs .f_blocks ) * sfs .f_frsize ;
fs_free = static_cast<Byte_Value>( sfs .f_bfree ) * sfs .f_bsize ;
}
else
error_message = "statvfs (" + mountpoint + "): " + Glib::strerror( errno ) ;
return ret ;
}
//private functions ...
//Read kernel version, reporting success or failure

43
src/ext2.cc
View File

@ -59,13 +59,18 @@ FS ext2::get_filesystem_support()
fs .move = FS::GPARTED ;
}
fs .online_read = FS::GPARTED ;
fs .online_read = FS::EXTERNAL ;
return fs ;
}
void ext2::set_used_sectors( Partition & partition )
{
//Called when file system is unmounted *and* when mounted. Always read
// the file system size from the on disk superblock using dumpe2fs to
// avoid overhead subtraction. Read the free space from the kernel via
// the statvfs() system call when mounted and from the superblock when
// unmounted.
if ( ! Utils::execute_command( "dumpe2fs -h " + partition .get_path(), output, error, true ) )
{
index = output .find( "Block count:" ) ;
@ -73,24 +78,42 @@ void ext2::set_used_sectors( Partition & partition )
sscanf( output.substr( index ) .c_str(), "Block count: %Ld", &T ) != 1 )
T = -1 ;
index = output .find( "Free blocks:" ) ;
if ( index >= output .length() ||
sscanf( output.substr( index ) .c_str(), "Free blocks: %Ld", &N ) != 1 )
N = -1 ;
index = output .find( "Block size:" ) ;
if ( index >= output.length() ||
sscanf( output.substr( index ) .c_str(), "Block size: %Ld", &S ) != 1 )
S = -1 ;
if ( T > -1 && N > -1 && S > -1 )
{
if ( T > -1 && S > -1 )
T = Utils::round( T * ( S / double(partition .sector_size) ) ) ;
N = Utils::round( N * ( S / double(partition .sector_size) ) ) ;
partition .set_sector_usage( T, N ) ;
if ( partition .busy )
{
Byte_Value ignored ;
Byte_Value fs_free ;
if ( Utils::get_mounted_filesystem_usage( partition .get_mountpoint(),
ignored, fs_free, error ) == 0 )
N = Utils::round( fs_free / double(partition .sector_size) ) ;
else
{
N = -1 ;
partition .messages .push_back( error ) ;
}
}
else
{
index = output .find( "Free blocks:" ) ;
if ( index >= output .length() ||
sscanf( output.substr( index ) .c_str(), "Free blocks: %Ld", &N ) != 1 )
N = -1 ;
if ( N > -1 && S > -1 )
N = Utils::round( N * ( S / double(partition .sector_size) ) ) ;
}
if ( T > -1 && N > -1 )
partition .set_sector_usage( T, N ) ;
}
else
{
if ( ! output .empty() )
partition .messages .push_back( output ) ;

43
src/ext3.cc
View File

@ -60,13 +60,18 @@ FS ext3::get_filesystem_support()
fs .move = GParted::FS::GPARTED ;
}
fs .online_read = FS::GPARTED ;
fs .online_read = FS::EXTERNAL ;
return fs ;
}
void ext3::set_used_sectors( Partition & partition )
{
//Called when file system is unmounted *and* when mounted. Always read
// the file system size from the on disk superblock using dumpe2fs to
// avoid overhead subtraction. Read the free space from the kernel via
// the statvfs() system call when mounted and from the superblock when
// unmounted.
if ( ! Utils::execute_command( "dumpe2fs -h " + partition .get_path(), output, error, true ) )
{
index = output .find( "Block count: " ) ;
@ -74,24 +79,42 @@ void ext3::set_used_sectors( Partition & partition )
sscanf( output .substr( index ) .c_str(), "Block count: %Ld", &T ) != 1 )
T = -1 ;
index = output .find( "Free blocks:" ) ;
if ( index >= output .length() ||
sscanf( output.substr( index ) .c_str(), "Free blocks: %Ld", &N ) != 1 )
N = -1 ;
index = output .find( "Block size:" ) ;
if ( index >= output.length() ||
sscanf( output.substr( index ) .c_str(), "Block size: %Ld", &S ) != 1 )
S = -1 ;
if ( T > -1 && N > -1 && S > -1 )
{
if ( T > -1 && S > -1 )
T = Utils::round( T * ( S / double(partition .sector_size) ) ) ;
N = Utils::round( N * ( S / double(partition .sector_size) ) ) ;
partition .set_sector_usage( T, N ) ;
if ( partition .busy )
{
Byte_Value ignored ;
Byte_Value fs_free ;
if ( Utils::get_mounted_filesystem_usage( partition .get_mountpoint(),
ignored, fs_free, error ) == 0 )
N = Utils::round( fs_free / double(partition .sector_size) ) ;
else
{
N = -1 ;
partition .messages .push_back( error ) ;
}
}
else
{
index = output .find( "Free blocks:" ) ;
if ( index >= output .length() ||
sscanf( output.substr( index ) .c_str(), "Free blocks: %Ld", &N ) != 1 )
N = -1 ;
if ( N > -1 && S > -1 )
N = Utils::round( N * ( S / double(partition .sector_size) ) ) ;
}
if ( T > -1 && N > -1 )
partition .set_sector_usage( T, N ) ;
}
else
{
if ( ! output .empty() )
partition .messages .push_back( output ) ;

43
src/ext4.cc
View File

@ -63,13 +63,18 @@ FS ext4::get_filesystem_support()
}
}
fs .online_read = FS::GPARTED ;
fs .online_read = FS::EXTERNAL ;
return fs ;
}
void ext4::set_used_sectors( Partition & partition )
{
//Called when file system is unmounted *and* when mounted. Always read
// the file system size from the on disk superblock using dumpe2fs to
// avoid overhead subtraction. Read the free space from the kernel via
// the statvfs() system call when mounted and from the superblock when
// unmounted.
if ( ! Utils::execute_command( "dumpe2fs -h " + partition .get_path(), output, error, true ) )
{
index = output .find( "Block count:" ) ;
@ -77,24 +82,42 @@ void ext4::set_used_sectors( Partition & partition )
sscanf( output.substr( index ) .c_str(), "Block count: %Ld", &T ) != 1 )
T = -1 ;
index = output .find( "Free blocks:" ) ;
if ( index >= output .length() ||
sscanf( output.substr( index ) .c_str(), "Free blocks: %Ld", &N ) != 1 )
N = -1 ;
index = output .find( "Block size:" ) ;
if ( index >= output.length() ||
sscanf( output.substr( index ) .c_str(), "Block size: %Ld", &S ) != 1 )
S = -1 ;
if ( T > -1 && N > -1 && S > -1 )
{
if ( T > -1 && S > -1 )
T = Utils::round( T * ( S / double(partition .sector_size) ) ) ;
N = Utils::round( N * ( S / double(partition .sector_size) ) ) ;
partition .set_sector_usage( T, N ) ;
if ( partition .busy )
{
Byte_Value ignored ;
Byte_Value fs_free ;
if ( Utils::get_mounted_filesystem_usage( partition .get_mountpoint(),
ignored, fs_free, error ) == 0 )
N = Utils::round( fs_free / double(partition .sector_size) ) ;
else
{
N = -1 ;
partition .messages .push_back( error ) ;
}
}
else
{
index = output .find( "Free blocks:" ) ;
if ( index >= output .length() ||
sscanf( output.substr( index ) .c_str(), "Free blocks: %Ld", &N ) != 1 )
N = -1 ;
if ( N > -1 && S > -1 )
N = Utils::round( N * ( S / double(partition .sector_size) ) ) ;
}
if ( T > -1 && N > -1 )
partition .set_sector_usage( T, N ) ;
}
else
{
if ( ! output .empty() )
partition .messages .push_back( output ) ;