Unlinking large files in IMFS

[Joel Sherrill]

Andy Dachs wrote:
> 
> I just updated my MPC8260 BSP to work with the rtems-ss-20010126 snapshot.  Its still a little rough around the edges but I came across a problem unlinking large files which I don't think is related to my BSP.  I saw similar symptoms with the beta3a release but never investigated fully.
> 
> Attached is a small test routine to demonstrate the problem.  Modify the NUM_BLOCKS value to get different file sizes (a value of 264 or above should generate the assertion).
> 
> Writing a 128k file and then calling unlink() is fine:
> 
> *** CRASH TEST, dummy? ***
> Writing file of 131584 bytes
> Written file
> Now trying to unlink it
> Success
> 
> Going to 135168 bytes generates an error:
> 
> *** CRASH TEST, dummy? ***
> Writing file of 135168 bytes
> Written file
> Now trying to unlink it
> assertion "0" failed: file "../../../../../../rtems-ss-20010126-afd/c/src/lib/libc/malloc.c", line 323
> 
> Just below that number is fine again:
> 
> *** CRASH TEST, dummy? ***
> Writing file of 134656 bytes
> Written file
> Now trying to unlink it
> Success
> 
> I should have enough heap (4M) so I don't think that's a problem.  By my calculations 135168 bytes is the magic number where triply indirect blocks would be required (for a filesystem using 128 byte blocks) so could it be related to that?

Definitely.  There is a different loop for singly, doubly and 
triply indirect blocks.  I think it is quite simple but you 
should test this and let me know.  



bash$ cvs diff -c memfile.c
Index: memfile.c
===================================================================
RCS file: /usr1/CVS/rtems/c/src/libfs/src/imfs/memfile.c,v
retrieving revision 1.13
diff -c -r1.13 memfile.c
*** memfile.c	2001/01/22 14:05:14	1.13
--- memfile.c	2001/03/22 20:13:50
***************
*** 509,514 ****
--- 509,516 ----
    if ( info->triply_indirect ) {
      for ( i=0 ; i<IMFS_MEMFILE_BLOCK_SLOTS ; i++ ) {
        p = (block_p *) info->triply_indirect[i];
+       if ( !p )
+          break;
        for ( j=0 ; j<IMFS_MEMFILE_BLOCK_SLOTS ; j++ ) {
          if ( p[j] ) {
            memfile_free_blocks_in_table( (block_p **)&p[j], to_free);


-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
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