[PATCH] update max_sectors documentation

The max_sectors has been split into max_hw_sectors and max_sectors for some
time. A patch to have blk_queue_max_sectors enforce this was sent by
me and it broke IDE. This patch updates the documentation.

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

diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt
index 8e63831971d5e4dc1eaf8622e4b9828cd679e1d5..f989a9e839b49abde7b12bfea3926aca9b3635a3 100644 (file)
--- a/Documentation/block/biodoc.txt
+++ b/Documentation/block/biodoc.txt
@@ -132,8 +132,18 @@ Some new queue property settings:
                limit. No highmem default.
 
        blk_queue_max_sectors(q, max_sectors)
-               Maximum size request you can handle in units of 512 byte
-               sectors. 255 default.
+               Sets two variables that limit the size of the request.
+
+               - The request queue's max_sectors, which is a soft size in
+               in units of 512 byte sectors, and could be dynamically varied
+               by the core kernel.
+
+               - The request queue's max_hw_sectors, which is a hard limit
+               and reflects the maximum size request a driver can handle
+               in units of 512 byte sectors.
+
+               The default for both max_sectors and max_hw_sectors is
+               255. The upper limit of max_sectors is 1024.
 
        blk_queue_max_phys_segments(q, max_segments)
                Maximum physical segments you can handle in a request. 128