Problems with bigblock support of fat

[Robert Reither]

I encounted really bad problems with 2048 Bytes/sec MO-Drive.
I'm using an Olympus PowerMO 640.
230MB Media works fine, but if i try to use 640(2048B/S) medias i'm really
in troubles. Looks quite the same as the problems i've reported for the
2.1.x kernels some time ago. (2.2.17/18 works fine 4 me).

OK, what i did :

Using kernel 2.4.0 on an Athlon TB 750 with 128 MB
MO was formated with FAT32.

i mounted the mo drive ...

i try to read a file from it (used : 'pico /mo/file.txt') ...
And got a nice crash : Segmentation Fault

OK, was easy to find this bug, fs/fat/cvf.c has a bug in bigblock_cvf struct
the field with the read function was a NULL.
I changed this to generic_file_read (like with default blocksize), and
tested it. First seemed to work fine, but :

I could read/write a file now, but the written data was not compatible
with DOS Systems (Tested under DOS6.22, WIN98SE) !

If i write a file to an empty MO-Disk, the start-cluster is 2 in the 
table. But the real data was written to (and also read from)
cluster 33 by linux !

I already posted this report to the maintainer of the fat-fs(Gordon Chaffee)
 a month ago, but i did not get a response yet. 
(tested it with kernel -test8 and -test9)

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Robert Reither                8925573 E754 (ja wirklich schon !!)
TU-Vienna
AUSTRIA
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