Re: ftruncate-mmap: pages are lost after writing to mmaped file.

From: Peter Zijlstra
Date: Tue Mar 24 2009 - 10:56:37 EST


On Tue, 2009-03-24 at 15:47 +0100, Jan Kara wrote:
>
> Or we could implement ext3_mkwrite() to allocate buffers already when we
> make page writeable. But it costs some performace (we have to write page
> full of zeros when allocating those buffers, where previously we didn't
> have to do anything) and it's not trivial to make it work if pagesize >
> blocksize (we should not allocate buffers outside of i_size so if i_size
> = 1024, we create just one block in ext3_mkwrite() but then we need to
> allocate more when we extend the file).

I think this is the best option, failing with SIGBUS when we fail to
allocate blocks seems consistent with other filesystems as well.

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