jbd2: fix sphinx kernel-doc build warnings

Sphinx emits various (26) warnings when building make target 'htmldocs'.
Currently struct definitions contain duplicate documentation, some as
kernel-docs and some as standard c89 comments.  We can reduce
duplication while cleaning up the kernel docs.

Move all kernel-docs to right above each struct member.  Use the set of
all existing comments (kernel-doc and c89).  Add documentation for
missing struct members and function arguments.
Signed-off-by: Tobin C. Harding <me@tobin.cc>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

fs/jbd2/transaction.c

@@ -492,8 +492,10 @@ void jbd2_journal_free_reserved(handle_t *handle)
 EXPORT_SYMBOL(jbd2_journal_free_reserved);
 
 /**
- * int jbd2_journal_start_reserved(handle_t *handle) - start reserved handle
+ * int jbd2_journal_start_reserved() - start reserved handle
  * @handle: handle to start
+ * @type: for handle statistics
+ * @line_no: for handle statistics
  *
  * Start handle that has been previously reserved with jbd2_journal_reserve().
  * This attaches @handle to the running transaction (or creates one if there's
@@ -623,6 +625,7 @@ int jbd2_journal_extend(handle_t *handle, int nblocks)
  * int jbd2_journal_restart() - restart a handle .
  * @handle:  handle to restart
  * @nblocks: nr credits requested
+ * @gfp_mask: memory allocation flags (for start_this_handle)
  *
  * Restart a handle for a multi-transaction filesystem
  * operation.