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author | Jens Axboe <jens.axboe@oracle.com> | 2009-02-24 08:10:09 +0100 |
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committer | Jens Axboe <jens.axboe@oracle.com> | 2009-02-26 10:45:48 +0100 |
commit | 9e973e64ac6dc504e6447d52193d4fff1a670156 (patch) | |
tree | 518cb0f34f9229f7faa81754733ce3926b84625c /fs/dlm | |
parent | 1e42807918d17e8c93bf14fbb74be84b141334c1 (diff) |
xen/blkfront: use blk_rq_map_sg to generate ring entries
On occasion, the request will apparently have more segments than we
fit into the ring. Jens says:
> The second problem is that the block layer then appears to create one
> too many segments, but from the dump it has rq->nr_phys_segments ==
> BLKIF_MAX_SEGMENTS_PER_REQUEST. I suspect the latter is due to
> xen-blkfront not handling the merging on its own. It should check that
> the new page doesn't form part of the previous page. The
> rq_for_each_segment() iterates all single bits in the request, not dma
> segments. The "easiest" way to do this is to call blk_rq_map_sg() and
> then iterate the mapped sg list. That will give you what you are
> looking for.
> Here's a test patch, compiles but otherwise untested. I spent more
> time figuring out how to enable XEN than to code it up, so YMMV!
> Probably the sg list wants to be put inside the ring and only
> initialized on allocation, then you can get rid of the sg on stack and
> sg_init_table() loop call in the function. I'll leave that, and the
> testing, to you.
[Moved sg array into info structure, and initialize once. -J]
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Diffstat (limited to 'fs/dlm')
0 files changed, 0 insertions, 0 deletions