Re: [PATCHv3 0/5] fix xfs by making I/O to vmap/vmalloc areas work

[Christoph Hellwig <hch@lst.de>]

On Fri, Feb 05, 2010 at 09:50:52AM -0600, James Bottomley wrote:
> From: James Bottomley <James.Bottomley@HansenPartnership.com>
> 
> This is essentially a small tidy up from the previous series.  I
> thought about the Ben H additions, but since power doesn't seem to
> need this, they seemed a bit moot (we can expand the API when an
> actual user comes along).
> 
> The patch series adds a flush/invalidate_kernel_vmap_range() API that
> drivers using vmap/vmalloc areas must use before sending tohse areas
> for I/O.  This makes it crystal clear that coherence on these areas is
> the responsibility of the driver alone.  Fortunately xfs is the only
> thing in the kernel actually doing I/O to vmap areas.
> 
> Sin ce xfs is completely broken on most VIPT architectures without
> this, I'd like to submit it as a bug fix for 2.6.33.  Unfortunately,
> we actually have some parisc xfs users whose data is curently at
> severe risk.

Agreed.  There's also a lot of ARM users popping up with this recently,
while others worked around it using local flushing hacks previously.