[Bug 2163] New: RFS file system : error in rtems_refs_group_bitmap_alloc group search algorithm

[bugzilla-daemon at rtems.org]

https://www.rtems.org/bugzilla/show_bug.cgi?id=2163

             Bug #: 2163
           Summary: RFS file system : error in
                    rtems_refs_group_bitmap_alloc group search algorithm
    Classification: Unclassified
           Product: RTEMS
           Version: HEAD
          Platform: All
        OS/Version: RTEMS
            Status: NEW
          Severity: normal
          Priority: P3
         Component: cpukit
        AssignedTo: joel.sherrill at oarcorp.com
        ReportedBy: Alan.P.Cudmore at nasa.gov


There is a bug in the rtems_rfs_group_bitmap_alloc function in
rtems-rfs-group.c

The file system will start at a target group to search for free blocks, then
alternatively search "above" and "below" that group until it finds a block. If
the  end of the groups are reached, it will do a linear search through the
blocks. 

The algorithm that searches "above" and "below" the groups will increment the
group offset each time it switches direction, causing some groups to be
skipped. If the group offset is incremented on every other direction switch,
then the groups will be searched without being skipped. 

This caused a problem in an application where there was a non-standard block
size, which caused the search to skip available blocks. 

I have a working patch for this, which I will submit.

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