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RAMFS problem
- To: ecos discussion list <ecos-discuss at sources dot redhat dot com>
- Subject: [ECOS] RAMFS problem
- From: Richard Panton <rpanton at 3glab dot com>
- Date: Fri, 20 Jul 2001 17:59:47 +0100 (BST)
It seems that ramfs is failing for files bigger than 0x8800 bytes (using
the default configuration).
When the fault occurs:
All 8 direct blocks are full.
The indirect block points to:
All 64 direct pointers used.
The indirect2 block points to:
Indirect block points to:
All 64 direct pointers used.
When an attempt is made to write to node->indirect2->indirect[1]->data, a
data fault occurs.
I think to fix this requires a change to findbuffer_indirect1():
Index: ramfs.c
===================================================================
RCS file: /cvs/ecos/ecos/packages/fs/ram/current/src/ramfs.c,v
retrieving revision 1.1
diff -r1.1 ramfs.c
777c777
< err = findbuffer_direct( bi,
---
> err = findbuffer_direct( bi * CYGNUM_RAMFS_BLOCK_SIZE,
===================================================================
Without the multiplier, bi (used here as an offset rather than a block
number) can range from 0 to CYGNUM_RAMFS_BLOCK_SIZE - 1
This ALWAYS falls inside the first (indirect) block, so the reference
later on in the function to blocks[bi] refers to an unassigned block.
(Also, at line 726, shouldn't that be:
if ( bi >= nblocks )
rather than
if ( bi > nblocks )
?????)
There's probably a similar sort of fix required in findbuffer_indirect2(),
but my head hurts enough already after trying to trace this through....
Nick, your name's on this one...
Best Regards,
Richard