When an md device stacks on top of a device which defines a
merge_bvec_fn, the md device must either call that function to check
that bios aren't created which are 'too big' (often a difficult thing
to do) or must ensure the bios never have more than a single page.
It came up in a recent discussion on dm-devel that the current
approach of limiting a request to PAGE_SIZE is not sufficient as you
could have several sub-page buffers.
So this patch changes to the use max_segments and
segment_boundary_mask to ensure there is only a single page - or part
there of - in a bio if an underlying device has a merge_bvec_fn.
This can affect 'xen' installations particularly.
This patch is tagged for -stable.
Thanks,
NeilBrown
The following changes since commit 25cf84cf377c0aae5dbcf937ea89bc7893db5176:
Linus Torvalds (1):
Merge git://git.kernel.org/.../amit/virtio-console
are available in the git repository at:
git://neil.brown.name/md/ for-linus
NeilBrown (1):
md: deal with merge_bvec_fn in component devices better.
drivers/md/linear.c | 12 +++++++-----
drivers/md/multipath.c | 20 ++++++++++++--------
drivers/md/raid0.c | 13 +++++++------
drivers/md/raid1.c | 28 +++++++++++++++++-----------
drivers/md/raid10.c | 28 +++++++++++++++++-----------
5 files changed, 60 insertions(+), 41 deletions(-)
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