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List:       linux-coda
Subject:    Re: Coda and Ext3
From:       Jan Harkes <jaharkes () cs ! cmu ! edu>
Date:       2001-09-19 15:47:23
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On Wed, Sep 19, 2001 at 10:23:36AM -0400, Sujal Shah wrote:
>      The Linux Coda drivers and the ext3 patches don't seem to get along
> very well, at least in Linux 2.4.7.  I've got a stock 2.4.7 kernel with
> a patch applied to the USB drivers (for a sony digital camera; see
> http://www.sujal.net/tech/linux/ just a change in unusual_devs.h). 
> 
> After I applied the ext3 patches from
> http://www.uow.edu.au/~andrewm/linux/ext3/ .  Basically, when an
> application tries to write to a file system mounted via coda, the
> application terminates with "Memory Fault" returned to the terminal. 
> THe file system still thinks it's busy (can't umount).

Yeah, I know, and it will probably work when you don't enable
data-journalling. Coda's kernelmodule currently uses generic_file_read
and generic_file_write on it's containerfiles, which works for many
filesystems. However, ext3fs (and tmpfs and several others) have a
filesystem specific write implementation and don't really like being
called with the generic functions.

The patch is simple, but I haven't made it yet. Basically we need to
wrap the read/write calls and call cii->c_cfile->f_op->file_write or
something.

> loaded, however.  Also, I backed out the patches for ext3 and the
> problem went away.

ext2 uses the generic file read/write functions, so whenever ext2 is the
underlying filesystem it all works fine.

Jan

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