Re: [PATCH 1/2] block: handle the null_mapped flag correctly in blk_rq_map_user_iov

From: Jens Axboe
Date: Wed Feb 11 2015 - 13:23:15 EST

On 02/11/2015 06:07 AM, Christoph Hellwig wrote:
The tape drivers (and the sg driver in a special case that doesn't matter
here) use the null_mapped flag to tell blk_rq_map_user to not copy around
any data into or out of the bounce buffers. blk_rq_map_user_iov never
got that treatment, which didn't matter until I refactored blk_rq_map_user
to be implemented in terms of blk_rq_map_user_iov.

So this fixes a regression caused by:

commit ddad8dd0a162fde61646a627a3017c258601dc8a
Author: Christoph Hellwig <hch@xxxxxx>
Date: Sun Jan 18 16:16:29 2015 +0100

block: use blk_rq_map_user_iov to implement blk_rq_map_user

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Ming Lei <tom.leiming@xxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxx>

which we should probably note in the commit. I'll add that.

Jens Axboe

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