Handle btrfs tools rounding of figures (#499202)
The btrfs programs only provide approximations of file system sizes
because they display figures using binary prefix multipliers to two
decimal places of precision. E.g. 2.00GB. For partition sizes where
the contained file system size rounds upwards, GParted will fail to read
the file system usage and report a warning because the file system will
appear to be larger than the partition.
For example, create a 2047 MiB partition containing a btrfs file system
and display its size.
# btrfs filesystem show
Label: none uuid: 92535375-5e76-4a70-896a-8d796a577993
Total devices 1 FS bytes used 28.00KB
devid 1 size 2.00GB used 240.62MB path /dev/sda12
The file system size appears to be 2048 MiB, but that is larger than the
partition, hence the issue GParted has. (Actually uses the btrfs devid
size which is the size of the btrfs file system within the partition in
question).
This issue is new with the fix for Bug #499202 because it queries the
file system sizes for the first time. The same issue could
theoretically occur previously, but with the used figure (FS bytes
used). This would have been virtually impossible to trigger because
btrfs file system would have to have been greater than 99% full, but
btrfs has been notorious for early reporting of file system full.
The fix is that if a btrfs file system size appears larger than the
partition size, but the minimum possible size which could have been
rounded to the reported figure is within the partition size use the
smaller partition size instead. Apply the method to the used figure
too, in case the file system is 100% full. Also if the btrfs file
system size appears smaller than the partition size, but the maximum
possible size which could have been rounded to the reported figure is
within the partition size use the larger partition size instead to avoid
reporting, presumably false, unallocated space. Not applied to file
system used figure.
Bug 499202 - gparted does not see the difference if partition size
differs from filesystem size
This commit is contained in:
Mike Fleetwood
Curtis Gedak
parent
7ddbc9bd92
commit
7fc16a1b69
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@ -45,7 +45,9 @@ public:
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bool check_repair( const Partition & partition, OperationDetail & operationdetail ) ;
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private:
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Sector btrfs_size_to_num( Glib::ustring s ) const ;
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Byte_Value btrfs_size_to_num( Glib::ustring str, Byte_Value ptn_bytes, bool scale_up ) const ;
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gdouble btrfs_size_max_delta( Glib::ustring str ) const ;
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gdouble btrfs_size_to_gdouble( Glib::ustring str ) const ;
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};
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} //GParted
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84
src/btrfs.cc
84
src/btrfs.cc
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@ -19,6 +19,8 @@
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#include "../include/btrfs.h"
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#include <ctype.h>
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namespace GParted
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{
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@ -117,7 +119,6 @@ bool btrfs::check_repair( const Partition & partition, OperationDetail & operati
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void btrfs::set_used_sectors( Partition & partition )
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{
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if ( btrfs_found )
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exit_status = Utils::execute_command( "btrfs filesystem show " + partition .get_path(), output, error, true ) ;
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else
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@ -130,15 +131,16 @@ void btrfs::set_used_sectors( Partition & partition )
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// file system wide used bytes (wrong for multi-device
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// file systems).
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Byte_Value ptn_bytes = partition .get_byte_length() ;
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Glib::ustring str ;
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//Btrfs file system device size
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Glib::ustring regexp = "devid .* size ([0-9\\.]+.?B) .* path " + partition .get_path() ;
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if ( ! ( str = Utils::regexp_label( output, regexp ) ) .empty() )
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T = btrfs_size_to_num( str ) ;
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T = btrfs_size_to_num( str, ptn_bytes, true ) ;
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//Btrfs file system wide used bytes
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if ( ! ( str = Utils::regexp_label( output, "FS bytes used ([0-9\\.]+.?B)" ) ) .empty() )
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N = T - btrfs_size_to_num( str ) ;
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N = T - btrfs_size_to_num( str, ptn_bytes, false ) ;
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if ( T > -1 && N > -1 )
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{
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@ -304,7 +306,79 @@ void btrfs::read_uuid( Partition & partition )
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}
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}
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Sector btrfs::btrfs_size_to_num( Glib::ustring str ) const
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//Private methods
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//Return the value of a btrfs tool formatted size, including reversing
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// changes in certain cases caused by using binary prefix multipliers
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// and rounding to two decimal places of precision. E.g. "2.00GB".
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Byte_Value btrfs::btrfs_size_to_num( Glib::ustring str, Byte_Value ptn_bytes, bool scale_up ) const
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{
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Byte_Value size_bytes = Utils::round( btrfs_size_to_gdouble( str ) ) ;
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gdouble delta = btrfs_size_max_delta( str ) ;
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Byte_Value upper_size = size_bytes + ceil( delta ) ;
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Byte_Value lower_size = size_bytes - floor( delta ) ;
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if ( size_bytes > ptn_bytes && lower_size <= ptn_bytes )
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{
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//Scale value down to partition size:
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// The btrfs tool reported size appears larger than the partition
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// size, but the minimum possible size which could have been rounded
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// to the reported figure is within the partition size so use the
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// smaller partition size instead. Applied to FS device size and FS
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// wide used bytes.
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// ............| ptn_bytes
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// [ x ) size_bytes with upper & lower size
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// x scaled down size_bytes
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// Do this to avoid the FS size or used bytes being larger than the
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// partition size and GParted failing to read the file system usage and
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// report a warning.
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size_bytes = ptn_bytes ;
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}
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else if ( scale_up && size_bytes < ptn_bytes && upper_size > ptn_bytes )
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{
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//Scale value up to partition size:
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// The btrfs tool reported size appears smaller than the partition
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// size, but the maximum possible size which could have been rounded
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// to the reported figure is within the partition size so use the
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// larger partition size instead. Applied to FS device size only.
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// ............| ptn_bytes
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// [ x ) size_bytes with upper & lower size
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// x scaled up size_bytes
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// Make an assumption that the file system actually fills the
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// partition, rather than is slightly smaller to avoid false reporting
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// of unallocated space.
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size_bytes = ptn_bytes ;
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}
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return size_bytes ;
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}
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//Return maximum delta for which num +/- delta would be rounded by btrfs
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// tools to str. E.g. btrfs_size_max_delta("2.00GB") -> 5368709.12
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gdouble btrfs::btrfs_size_max_delta( Glib::ustring str ) const
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{
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Glib::ustring limit_str ;
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//Create limit_str. E.g. str = "2.00GB" -> limit_str = "0.005GB"
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for ( Glib::ustring::iterator p = str .begin() ; p != str .end() ; p ++ )
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{
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if ( isdigit( *p ) )
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limit_str .append( "0" ) ;
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else if ( *p == '.' )
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limit_str .append( "." ) ;
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else
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{
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limit_str .append( "5" ) ;
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limit_str .append( p, str .end() ) ;
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break ;
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}
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}
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gdouble max_delta = btrfs_size_to_gdouble( limit_str ) ;
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return max_delta ;
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}
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//Return the value of a btrfs tool formatted size.
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// E.g. btrfs_size_to_gdouble("2.00GB") -> 2147483648.0
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gdouble btrfs::btrfs_size_to_gdouble( Glib::ustring str ) const
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{
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gchar * suffix ;
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gdouble rawN = g_ascii_strtod( str .c_str(), & suffix ) ;
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@ -317,7 +391,7 @@ Sector btrfs::btrfs_size_to_num( Glib::ustring str ) const
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case 'T': mult = TEBIBYTE ; break ;
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default: mult = 1 ; break ;
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}
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return Utils::round( rawN * mult ) ;
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return rawN * mult ;
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}
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} //GParted
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