block: add a proper block layer data direction encoding

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Currently the block layer op_is_write, bio_data_dir and rq_data_dir
helper treat every operation that is not a READ as a data out operation.
This worked surprisingly long, but the new REQ_OP_ZONE_REPORT operation
actually adds a second operation that reads data from the device.
Surprisingly nothing critical relied on this direction, but this might
be a good opportunity to properly fix this issue up.

We take a little inspiration and use the least significant bit of the
operation number to encode the data direction, which just requires us
to renumber the operations to fix this scheme.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

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Christoph Hellwig 2016-10-20 15:12:15 +02:00 • committed by Jens Axboe

parent ef295ecf09

commit 87374179c5

2 changed files with 30 additions and 13 deletions

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38

include/linux/blk_types.h

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5

include/linux/fs.h

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