block: better op and flags encoding

Now that we don't need the common flags to overflow outside the range
of a 32-bit type we can encode them the same way for both the bio and
request fields.  This in addition allows us to place the operation
first (and make some room for more ops while we're at it) and to
stop having to shift around the operation values.

In addition this allows passing around only one value in the block layer
instead of two (and eventuall also in the file systems, but we can do
that later) and thus clean up a lot of code.

Last but not least this allows decreasing the size of the cmd_flags
field in struct request to 32-bits.  Various functions passing this
value could also be updated, but I'd like to avoid the churn for now.

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

1 files changed, 2 insertions, 2 deletions

diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt
index 6acea160298c..01ddeaf64b0f 100644
--- a/Documentation/block/biodoc.txt
+++ b/Documentation/block/biodoc.txt
@@ -553,8 +553,8 @@ struct request {
 	struct request_list *rl;
 }
 	
-See the rq_flag_bits definitions for an explanation of the various flags
-available. Some bits are used by the block layer or i/o scheduler.
+See the req_ops and req_flag_bits definitions for an explanation of the various
+flags available. Some bits are used by the block layer or i/o scheduler.
 	
 The behaviour of the various sector counts are almost the same as before,
 except that since we have multi-segment bios, current_nr_sectors refers