Fix misspellings collected by members of KJ list.

Fix the misspellings of "propogate", "writting" and (oh, the shame
:-) "kenrel" in the source tree.

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
diff --git a/fs/direct-io.c b/fs/direct-io.c
index d9d0833..1e88d8d 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -439,7 +439,7 @@
  * Wait on and process all in-flight BIOs.  This must only be called once
  * all bios have been issued so that the refcount can only decrease.
  * This just waits for all bios to make it through dio_bio_complete.  IO
- * errors are propogated through dio->io_error and should be propogated via
+ * errors are propagated through dio->io_error and should be propagated via
  * dio_complete().
  */
 static void dio_await_completion(struct dio *dio)