cramfs root filesystem corruption

[Paul Ruhland]

I've found a few posts similar to this from about a year back in the main
kernel list but I could never follow the thread to any conclusion.

I'm running a cramfs root filesystem on an 850 system, linux-2.4.4 ( from denx
).  Everything has been running fine but the cramfs filesystem has started
behaving badly.

The cramfs image is in flash, mounted as root via mtd blockdevice.

Typically the error occurs during flash reprogramming ( using mtd char device
'/dev/mtd0' ) ...during/after flash programming the cramfs filesystem 'loses'
information ( files disappear ).  The errors from syslog are 'error during
decompression', typically the error numbers ( from 'linux/zlib_fs.h' ) are
Z_BUF_ERROR, for the first error,  and Z_DATA_ERROR for the rest.  I've got
my BDI breaking at the uncompress error and the source length is huge:

(gdb) frame 0
#0  cramfs_uncompress_block (dst=0xc078c000, dstlen=4096, src=0xc0145ac0,
srclen=4969176) at uncompress.c:49

The reprogramming of the flash is successful, all new data has been written to
the correct location(s).  The cramfs image ( root filesystem ) in flash is
NOT corrupt.  A hard reboot and everything is fine.

Has anyone seen such cramfs problem before?  I'm just looking to see if there
is any 'known' problems before I get to far into debugging this thing.

--
Paul Ruhland

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/