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_buf_item.c b/fs/xfs/xfs_buf_item.c
index 7b7e005..da399ac 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -420,7 +420,7 @@
 
 	if (freed && stale) {
 		ASSERT(bip->bli_flags & XFS_BLI_STALE);
-		ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
+		ASSERT(xfs_buf_islocked(bp));
 		ASSERT(!(XFS_BUF_ISDELAYWRITE(bp)));
 		ASSERT(XFS_BUF_ISSTALE(bp));
 		ASSERT(bip->bli_format.blf_flags & XFS_BLF_CANCEL);
@@ -483,7 +483,7 @@
 
 	if (XFS_BUF_ISPINNED(bp))
 		return XFS_ITEM_PINNED;
-	if (!XFS_BUF_CPSEMA(bp))
+	if (!xfs_buf_trylock(bp))
 		return XFS_ITEM_LOCKED;
 
 	/* take a reference to the buffer.  */
@@ -905,7 +905,7 @@
 	xfs_log_item_t	*head_lip;
 
 	ASSERT(XFS_BUF_ISBUSY(bp));
-	ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
+	ASSERT(xfs_buf_islocked(bp));
 
 	lip->li_cb = cb;
 	if (XFS_BUF_FSPRIVATE(bp, void *) != NULL) {