xfs: simplify buffer pinning

Get rid of the xfs_buf_pin/xfs_buf_unpin/xfs_buf_ispin helpers and opencode
them in their only callers, just like we did for the inode pinning a while
ago.  Also remove duplicate trace points - the bufitem tracepoints cover
all the information that is present in a buffer tracepoint.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

diff --git a/fs/xfs/linux-2.6/xfs_buf.h b/fs/xfs/linux-2.6/xfs_buf.h
index 5fbecef..2a9749a 100644
--- a/fs/xfs/linux-2.6/xfs_buf.h
+++ b/fs/xfs/linux-2.6/xfs_buf.h
@@ -258,11 +258,6 @@
 /* Buffer Utility Routines */
 extern xfs_caddr_t xfs_buf_offset(xfs_buf_t *, size_t);
 
-/* Pinning Buffer Storage in Memory */
-extern void xfs_buf_pin(xfs_buf_t *);
-extern void xfs_buf_unpin(xfs_buf_t *);
-extern int xfs_buf_ispin(xfs_buf_t *);
-
 /* Delayed Write Buffer Routines */
 extern void xfs_buf_delwri_dequeue(xfs_buf_t *);
 extern void xfs_buf_delwri_promote(xfs_buf_t *);
@@ -351,7 +346,7 @@
 #define XFS_BUF_SET_VTYPE(bp, type)		do { } while (0)
 #define XFS_BUF_SET_REF(bp, ref)		do { } while (0)
 
-#define XFS_BUF_ISPINNED(bp)	xfs_buf_ispin(bp)
+#define XFS_BUF_ISPINNED(bp)	atomic_read(&((bp)->b_pin_count))
 
 #define XFS_BUF_VALUSEMA(bp)	xfs_buf_lock_value(bp)
 #define XFS_BUF_CPSEMA(bp)	(xfs_buf_cond_lock(bp) == 0)
@@ -370,8 +365,6 @@
 	xfs_buf_rele(bp);
 }
 
-#define xfs_bpin(bp)		xfs_buf_pin(bp)
-#define xfs_bunpin(bp)		xfs_buf_unpin(bp)
 #define xfs_biodone(bp)		xfs_buf_ioend(bp, 0)
 
 #define xfs_biomove(bp, off, len, data, rw) \