Fix DMA access of block device in 64-bit kernel on some non-x86 systems with 4GB or upper 4GB memory

For some non-x86 systems with 4GB or upper 4GB memory,
we need increase the range of addresses that can be
used for direct DMA in 64-bit kernel.
Signed-off-by: NYang Shi <yang.shi@windriver.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Block layer alignment was used for two different purposes - memory
alignment and padding.  This causes problems in lower layers because
drivers which only require memory alignment ends up with adjusted
rq->data_len.  Separate out padding such that padding occurs iff
driver explicitly requests it.

Tomo: restorethe code to update bio in blk_rq_map_user
      introduced by the commit 40b01b9b
      according to padding alignment.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

kernel-doc for block/:
- add missing parameters
- fix one function's parameter list (remove blank line)
- add 2 source files to docbook for non-exported kernel-doc functions
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Draining shouldn't be done for commands where overflow may indicate
data integrity issues.  Add dma_drain_needed callback to
request_queue.  Drain buffer is appened iff this function returns
non-zero.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

blk_settings_init() can become static.
Signed-off-by: NAdrian Bunk <bunk@kernel.org>
Signed-off-by: NJens Axboe <axboe@carl.home.kernel.dk>

Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Adds files for barrier handling, rq execution, io context handling,
mapping data to requests, and queue settings.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>