[xfs-masters] [PATCH 0/6] Handle bio_alloc failure

[Theodore Tso]

On Tue, Apr 14, 2009 at 08:20:49PM +0200, Jens Axboe wrote:
> 
> It's a bio_alloc() guarantee, it uses a mempool backing. And if you use
> a mempool backing, any allocation that can wait will always be
> satisfied.
> 

Am I missing something?  I don't see anything in
include/linux/mempool.h or mm/mempool.c, or in block/blk-core.c or
include/linux/bio.h which documents that GFP_WAIT implies that
bio_alloc() will always succeed.   

My concern is that at some point in the future, someone either in the
block device layer or in mm/mempool.c will consider this an
implementation detail, and all of sudden calls to bio_alloc() with
GFP_WAIT will start failing and the resulting hilarty which ensues
won't be easily predicted by the developer making this change.

Regards,

					- Ted