tree 17a50abdadaa58686983510230932323bf5d123c
parent e0489487ec9cd79ee1fa0dc5d3789c08b0e51a2c
author Jens Axboe <axboe@fb.com> 1460485966 -0600
committer Jens Axboe <axboe@fb.com> 1460497587 -0600

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

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>