[XFS] Kill off xfs_count_bits

xfs_count_bits is only called once, and is then compared to 0. IOW, what
it really wants to know is, is the bitmap empty. This can be done more
simply, certainly.

SGI-PV: 966503
SGI-Modid: xfs-linux-melb:xfs-kern:28944a

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>

diff --git a/fs/xfs/xfs_bit.c b/fs/xfs/xfs_bit.c
index 1afe07f67e3b2e9ea0e0e8d02eb0a99e2478e0eb..fab0b6d5a41be3916ac8893a2f82f142cd4443f4 100644 (file)
--- a/fs/xfs/xfs_bit.c
+++ b/fs/xfs/xfs_bit.c
@@ -65,44 +65,6 @@ static const char xfs_highbit[256] = {
 };
 #endif
 
-/*
- * Count of bits set in byte, 0..8.
- */
-static const char xfs_countbit[256] = {
-       0, 1, 1, 2, 1, 2, 2, 3,                 /* 00 .. 07 */
-       1, 2, 2, 3, 2, 3, 3, 4,                 /* 08 .. 0f */
-       1, 2, 2, 3, 2, 3, 3, 4,                 /* 10 .. 17 */
-       2, 3, 3, 4, 3, 4, 4, 5,                 /* 18 .. 1f */
-       1, 2, 2, 3, 2, 3, 3, 4,                 /* 20 .. 27 */
-       2, 3, 3, 4, 3, 4, 4, 5,                 /* 28 .. 2f */
-       2, 3, 3, 4, 3, 4, 4, 5,                 /* 30 .. 37 */
-       3, 4, 4, 5, 4, 5, 5, 6,                 /* 38 .. 3f */
-       1, 2, 2, 3, 2, 3, 3, 4,                 /* 40 .. 47 */
-       2, 3, 3, 4, 3, 4, 4, 5,                 /* 48 .. 4f */
-       2, 3, 3, 4, 3, 4, 4, 5,                 /* 50 .. 57 */
-       3, 4, 4, 5, 4, 5, 5, 6,                 /* 58 .. 5f */
-       2, 3, 3, 4, 3, 4, 4, 5,                 /* 60 .. 67 */
-       3, 4, 4, 5, 4, 5, 5, 6,                 /* 68 .. 6f */
-       3, 4, 4, 5, 4, 5, 5, 6,                 /* 70 .. 77 */
-       4, 5, 5, 6, 5, 6, 6, 7,                 /* 78 .. 7f */
-       1, 2, 2, 3, 2, 3, 3, 4,                 /* 80 .. 87 */
-       2, 3, 3, 4, 3, 4, 4, 5,                 /* 88 .. 8f */
-       2, 3, 3, 4, 3, 4, 4, 5,                 /* 90 .. 97 */
-       3, 4, 4, 5, 4, 5, 5, 6,                 /* 98 .. 9f */
-       2, 3, 3, 4, 3, 4, 4, 5,                 /* a0 .. a7 */
-       3, 4, 4, 5, 4, 5, 5, 6,                 /* a8 .. af */
-       3, 4, 4, 5, 4, 5, 5, 6,                 /* b0 .. b7 */
-       4, 5, 5, 6, 5, 6, 6, 7,                 /* b8 .. bf */
-       2, 3, 3, 4, 3, 4, 4, 5,                 /* c0 .. c7 */
-       3, 4, 4, 5, 4, 5, 5, 6,                 /* c8 .. cf */
-       3, 4, 4, 5, 4, 5, 5, 6,                 /* d0 .. d7 */
-       4, 5, 5, 6, 5, 6, 6, 7,                 /* d8 .. df */
-       3, 4, 4, 5, 4, 5, 5, 6,                 /* e0 .. e7 */
-       4, 5, 5, 6, 5, 6, 6, 7,                 /* e8 .. ef */
-       4, 5, 5, 6, 5, 6, 6, 7,                 /* f0 .. f7 */
-       5, 6, 6, 7, 6, 7, 7, 8,                 /* f8 .. ff */
-};
-
 /*
  * xfs_highbit32: get high bit set out of 32-bit argument, -1 if none set.
  */
@@ -167,56 +129,21 @@ xfs_highbit64(
 
 
 /*
- * Count the number of bits set in the bitmap starting with bit
- * start_bit.  Size is the size of the bitmap in words.
- *
- * Do the counting by mapping a byte value to the number of set
- * bits for that value using the xfs_countbit array, i.e.
- * xfs_countbit[0] == 0, xfs_countbit[1] == 1, xfs_countbit[2] == 1,
- * xfs_countbit[3] == 2, etc.
+ * Return whether bitmap is empty.
+ * Size is number of words in the bitmap, which is padded to word boundary
+ * Returns 1 for empty, 0 for non-empty.
  */
 int
-xfs_count_bits(uint *map, uint size, uint start_bit)
+xfs_bitmap_empty(uint *map, uint size)
 {
-       register int    bits;
-       register unsigned char  *bytep;
-       register unsigned char  *end_map;
-       int             byte_bit;
-
-       bits = 0;
-       end_map = (char*)(map + size);
-       bytep = (char*)(map + (start_bit & ~0x7));
-       byte_bit = start_bit & 0x7;
-
-       /*
-        * If the caller fell off the end of the map, return 0.
-        */
-       if (bytep >= end_map) {
-               return (0);
-       }
-
-       /*
-        * If start_bit is not byte aligned, then process the
-        * first byte separately.
-        */
-       if (byte_bit != 0) {
-               /*
-                * Shift off the bits we don't want to look at,
-                * before indexing into xfs_countbit.
-                */
-               bits += xfs_countbit[(*bytep >> byte_bit)];
-               bytep++;
-       }
+       uint i;
+       uint ret = 0;
 
-       /*
-        * Count the bits in each byte until the end of the bitmap.
-        */
-       while (bytep < end_map) {
-               bits += xfs_countbit[*bytep];
-               bytep++;
+       for (i = 0; i < size; i++) {
+               ret |= map[i];
        }
 
-       return (bits);
+       return (ret == 0);
 }
 
 /*

diff --git a/fs/xfs/xfs_bit.h b/fs/xfs/xfs_bit.h
index 0bbe568175428f4759a6a7ef1d89b0f6bd60baef..082641a9782c073e832fab360d88d98020f87310 100644 (file)
--- a/fs/xfs/xfs_bit.h
+++ b/fs/xfs/xfs_bit.h
@@ -55,8 +55,8 @@ extern int xfs_lowbit64(__uint64_t v);
 /* Get high bit set out of 64-bit argument, -1 if none set */
 extern int xfs_highbit64(__uint64_t);
 
-/* Count set bits in map starting with start_bit */
-extern int xfs_count_bits(uint *map, uint size, uint start_bit);
+/* Return whether bitmap is empty (1 == empty) */
+extern int xfs_bitmap_empty(uint *map, uint size);
 
 /* Count continuous one bits in map starting with start_bit */
 extern int xfs_contig_bits(uint *map, uint size, uint start_bit);

diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index 6c1bddc04e316557e47d9cf148468791c9b23e61..b0667cb27d6652be3db6731edb646da03eb7584c 100644 (file)
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -580,8 +580,8 @@ xfs_buf_item_unlock(
         * If the buf item isn't tracking any data, free it.
         * Otherwise, if XFS_BLI_HOLD is set clear it.
         */
-       if (xfs_count_bits(bip->bli_format.blf_data_map,
-                             bip->bli_format.blf_map_size, 0) == 0) {
+       if (xfs_bitmap_empty(bip->bli_format.blf_data_map,
+                            bip->bli_format.blf_map_size)) {
                xfs_buf_item_relse(bp);
        } else if (hold) {
                bip->bli_flags &= ~XFS_BLI_HOLD;