From f908ee9463b09ddd05e1c1a0111132212dc05fac Mon Sep 17 00:00:00 2001
From: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
Date: Fri, 11 May 2012 16:36:44 +0200
Subject: [PATCH] bio allocation failure due to bio_get_nr_vecs()

The number of bio_get_nr_vecs() is passed down via bio_alloc() to
bvec_alloc_bs(), which fails the bio allocation if
nr_iovecs > BIO_MAX_PAGES. For the underlying caller this causes an
unexpected bio allocation failure.
Limiting to queue_max_segments() is not sufficient, as max_segments
also might be very large.

bvec_alloc_bs(gfp_mask, nr_iovecs, ) => NULL when nr_iovecs  > BIO_MAX_PAGES
bio_alloc_bioset(gfp_mask, nr_iovecs, ...)
bio_alloc(GFP_NOIO, nvecs)
xfs_alloc_ioend_bio()

Signed-off-by: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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