gfs2: Fix a number of kernel-doc warnings

Building the kernel with W=1 results in a number of kernel-doc warnings
like incorrect function names and parameter descriptions.  Fix those,
mostly by adding missing parameter descriptions, removing left-over
descriptions, and demoting some less important kernel-doc comments into
regular comments.

Originally proposed by Lee Jones; improved and combined into a single
patch by Andreas.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
index b4fd461..d68184e 100644
--- a/fs/gfs2/meta_io.c
+++ b/fs/gfs2/meta_io.c
@@ -243,6 +243,7 @@ static void gfs2_submit_bhs(int op, int op_flags, struct buffer_head *bhs[],
  * @gl: The glock covering the block
  * @blkno: The block number
  * @flags: flags
+ * @rahead: Do read-ahead
  * @bhp: the place where the buffer is returned (NULL on failure)
  *
  * Returns: errno