Re: [PATCH, RFC] xip: use i_mutex for xip_file_fault

From: Al Viro
Date: Sat Sep 10 2011 - 11:56:46 EST


On Sat, Sep 10, 2011 at 05:31:39PM +0200, Marco Stornelli wrote:
> From: Marco Stornelli <marco.stornelli@xxxxxxxxx>
>
> There aren't sufficient sync points for a fs for xip operations. In
> particular for the mmap case. It can be not sufficient to lock/unlock
> to do some operation inside get_xip_mem callback. For xip_file_read
> it's really easy to write a fs specific wrapper, xip_file_write hold
> i_mutex so no problem. With this patch we can avoid concurrent truncate
> operation and xip mmap.

Umm... I really don't like that; what's going to happen if you have a file
mmapped and do write() to that file from address in that mapping?
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