tree a1a0c4836289df86bb62e7eae5c80c66fca1643a
parent 0568b409c74f7a125d92a09a3f386785700ef688
author Jens Axboe <axboe@suse.de> 1146506343 +0200
committer Jens Axboe <axboe@suse.de> 1146506343 +0200

[PATCH] pipe: introduce ->pin() buffer operation

The ->map() function is really expensive on highmem machines right now,
since it has to use the slower kmap() instead of kmap_atomic(). Splice
rarely needs to access the virtual address of a page, so it's a waste
of time doing it.

Introduce ->pin() to take over the responsibility of making sure the
page data is valid. ->map() is then reduced to just kmap(). That way we
can also share a most of the pipe buffer ops between pipe.c and splice.c

Signed-off-by: Jens Axboe <axboe@suse.de>