[XFS] Use the generic bitops rather than implementing them ourselves.

This keeps xfs_lowbit64 as it was since there aren't good generic helpers
there ... Patch inspired by Andi Kleen.

SGI-PV: 981498

SGI-Modid: xfs-linux-melb:xfs-kern:31472a

Signed-off-by: David Chinner <david@fromorbit.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Donald Douwsma <donaldd@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

1 files changed, 30 insertions, 4 deletions

diff --git a/fs/xfs/xfs_bit.h b/fs/xfs/xfs_bit.h
index 082641a9782c..8e0e463dae2d 100644
--- a/fs/xfs/xfs_bit.h
+++ b/fs/xfs/xfs_bit.h
@@ -47,13 +47,39 @@ static inline __uint64_t xfs_mask64lo(int n)
 }
 
 /* Get high bit set out of 32-bit argument, -1 if none set */
-extern int xfs_highbit32(__uint32_t v);
+static inline int xfs_highbit32(__uint32_t v)
+{
+        return fls(v) - 1;
+}
+
+/* Get high bit set out of 64-bit argument, -1 if none set */
+static inline int xfs_highbit64(__uint64_t v)
+{
+        return fls64(v) - 1;
+}
+
+/* Get low bit set out of 32-bit argument, -1 if none set */
+static inline int xfs_lowbit32(__uint32_t v)
+{
+        unsigned long   t = v;
+        return (v) ? find_first_bit(&t, 32) : -1;
+}
 
 /* Get low bit set out of 64-bit argument, -1 if none set */
-extern int xfs_lowbit64(__uint64_t v);
+static inline int xfs_lowbit64(__uint64_t v)
+{
+        __uint32_t      w = (__uint32_t)v;
+        int             n = 0;
 
-/* Get high bit set out of 64-bit argument, -1 if none set */
-extern int xfs_highbit64(__uint64_t);
+        if (w) {        /* lower bits */
+                n = ffs(w);
+        } else {        /* upper bits */
+                w = (__uint32_t)(v >> 32);
+                if (w && (n = ffs(w)))
+                n += 32;
+        }
+        return n - 1;
+}
 
 /* Return whether bitmap is empty (1 == empty) */
 extern int xfs_bitmap_empty(uint *map, uint size);