Merge branch 'upstream-linus' of master.kernel.org:/pub/scm/linux/kernel/git/jgarzik...

[~andy/linux] / Documentation / block / biodoc.txt

diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt
index 980a6e6f5981236cca2f9c06156a03db8ef0d225..3adaace328a660fac9591e7a4b0726661dd3d832 100644 (file)
--- a/Documentation/block/biodoc.txt
+++ b/Documentation/block/biodoc.txt
@@ -183,7 +183,7 @@ it, the pci dma mapping routines and associated data structures have now been
 modified to accomplish a direct page -> bus translation, without requiring
 a virtual address mapping (unlike the earlier scheme of virtual address
 -> bus translation). So this works uniformly for high-memory pages (which
-do not have a correponding kernel virtual address space mapping) and
+do not have a corresponding kernel virtual address space mapping) and
 low-memory pages.
 
 Note: Please refer to DMA-mapping.txt for a discussion on PCI high mem DMA
@@ -946,6 +946,13 @@ elevator_merged_fn         called when a request in the scheduler has been
                                scheduler for example, to reposition the request
                                if its sorting order has changed.
 
+elevator_allow_merge_fn                called whenever the block layer determines
+                               that a bio can be merged into an existing
+                               request safely. The io scheduler may still
+                               want to stop a merge at this point if it
+                               results in some sort of conflict internally,
+                               this hook allows it to do that.
+
 elevator_dispatch_fn           fills the dispatch queue with ready requests.
                                I/O schedulers are free to postpone requests by
                                not filling the dispatch queue unless @force
@@ -1013,7 +1020,7 @@ Characteristics:
 i. Binary tree
 AS and deadline i/o schedulers use red black binary trees for disk position
 sorting and searching, and a fifo linked list for time-based searching. This
-gives good scalability and good availablility of information. Requests are
+gives good scalability and good availability of information. Requests are
 almost always dispatched in disk sort order, so a cache is kept of the next
 request in sort order to prevent binary tree lookups.