dm mpath: add optional "queue_mode" feature

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Allow a user to specify an optional feature 'queue_mode <mode>' where
<mode> may be "bio", "rq" or "mq" -- which corresponds to bio-based,
request_fn rq-based, and blk-mq rq-based respectively.

If the queue_mode feature isn't specified the default for the
"multipath" target is still "rq" but if dm_mod.use_blk_mq is set to Y
it'll default to mode "mq".

This new queue_mode feature introduces the ability for each multipath
device to have its own queue_mode (whereas before this feature all
multipath devices effectively had to have the same queue_mode).

This commit also goes a long way to eliminate the awkward (ab)use of
DM_TYPE_*, the associated filter_md_type() and other relatively fragile
and difficult to maintain code.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>

...

This commit is contained in:

Mike Snitzer 2016-05-24 21:16:51 -04:00

parent bf661be1fc

commit e83068a5fa

7 changed files with 159 additions and 119 deletions

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149

drivers/md/dm-mpath.c

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19

drivers/md/dm-rq.c

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2

drivers/md/dm-rq.h

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67

drivers/md/dm-table.c

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15

drivers/md/dm.c

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10

drivers/md/dm.h

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16

include/linux/device-mapper.h

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