Test1:

root@darkstar:/mnt/host# mount -t jffs2 /dev/mtdblock0 /mnt/test
root@darkstar:/mnt/host# cd /mnt/test
root@darkstar:/mnt/test# cp -R /usr .
cp: writing `./usr/bin/indent': Input/output error
jffs2_flash_writev(): Non-contiguous write to 01f802a4
wbuf was previously 01f80010-01f802b4
Kernel panic - not syncing: BUG!

Test2:
root@darkstar:/mnt/test# cp /bin/mount .
cp: writing `./mount': Input/output error
root@darkstar:/mnt/test# dmesg | tail
mtdramecc: overwrite of ECC block 9437184 at 9437200
jffs2_flush_wbuf(): Write failed with -5
mtdramecc: overwrite of ECC block 9043968 at 9043984
jffs2_flush_wbuf(): Write failed with -5
mtdramecc: overwrite of ECC block 9175040 at 9175056
jffs2_flush_wbuf(): Write failed with -5
mtdramecc: overwrite of ECC block 8781824 at 8781840
jffs2_flush_wbuf(): Write failed with -5
mtdramecc: overwrite of ECC block 8912896 at 8912912
jffs2_flush_wbuf(): Write failed with -5