block: add ability to flag write back caching on a device

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Add an internal helper and flag for setting whether a queue has
write back caching, or write through (or none). Add a sysfs file
to show this as well, and make it changeable from user space.

This will replace the (awkward) blk_queue_flush() interface that
drivers currently use to inform the block layer of write cache state
and capabilities.

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

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This commit is contained in:

Jens Axboe 2016-04-12 12:32:46 -06:00

parent e0489487ec

commit 93e9d8e836

4 changed files with 77 additions and 0 deletions

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9

Documentation/block/queue-sysfs.txt

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26

block/blk-settings.c

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39

block/blk-sysfs.c

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3

include/linux/blkdev.h

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