xfs: clean up buffer locking helpers

Rename xfs_buf_cond_lock and reverse it's return value to fit most other
trylock operations in the Kernel and XFS (with the exception of down_trylock,
after which xfs_buf_cond_lock was modelled), and replace xfs_buf_lock_val
with an xfs_buf_islocked for use in asserts, or and opencoded variant in
tracing.  remove the XFS_BUF_* wrappers for all the locking helpers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
diff --git a/fs/xfs/xfs_trans_buf.c b/fs/xfs/xfs_trans_buf.c
index 03b3b7f..bd54457 100644
--- a/fs/xfs/xfs_trans_buf.c
+++ b/fs/xfs/xfs_trans_buf.c
@@ -160,7 +160,7 @@
 	 */
 	bp = xfs_trans_buf_item_match(tp, target_dev, blkno, len);
 	if (bp != NULL) {
-		ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
+		ASSERT(xfs_buf_islocked(bp));
 		if (XFS_FORCED_SHUTDOWN(tp->t_mountp))
 			XFS_BUF_SUPER_STALE(bp);
 
@@ -327,7 +327,7 @@
 	 */
 	bp = xfs_trans_buf_item_match(tp, target, blkno, len);
 	if (bp != NULL) {
-		ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
+		ASSERT(xfs_buf_islocked(bp));
 		ASSERT(XFS_BUF_FSPRIVATE2(bp, xfs_trans_t *) == tp);
 		ASSERT(XFS_BUF_FSPRIVATE(bp, void *) != NULL);
 		ASSERT((XFS_BUF_ISERROR(bp)) == 0);