xfs
[Top] [All Lists]

[PATCH] Clean up bitops

To: xfs@xxxxxxxxxxx
Subject: [PATCH] Clean up bitops
From: David Chinner <dgc@xxxxxxx>
Date: Tue, 30 Oct 2007 10:36:35 +1100
Cc: xfs-dev@xxxxxxx
Sender: xfs-bounce@xxxxxxxxxxx
User-agent: Mutt/1.4.2.1i
Use the generic bitops rather than implementing them ourselves.
Patch inspired by Andi Kleen.

Signed-off-by: Dave Chinner <dgc@xxxxxxx>
---
 fs/xfs/xfs_bit.c     |  103 ---------------------------------------------------
 fs/xfs/xfs_bit.h     |   27 ++++++++++---
 fs/xfs/xfs_rtalloc.c |   19 +++------
 3 files changed, 29 insertions(+), 120 deletions(-)

Index: 2.6.x-xfs-new/fs/xfs/xfs_bit.c
===================================================================
--- 2.6.x-xfs-new.orig/fs/xfs/xfs_bit.c 2007-06-20 15:54:59.000000000 +1000
+++ 2.6.x-xfs-new/fs/xfs/xfs_bit.c      2007-10-05 08:48:48.107390247 +1000
@@ -25,109 +25,6 @@
  * XFS bit manipulation routines, used in non-realtime code.
  */
 
-#ifndef HAVE_ARCH_HIGHBIT
-/*
- * Index of high bit number in byte, -1 for none set, 0..7 otherwise.
- */
-static const char xfs_highbit[256] = {
-       -1, 0, 1, 1, 2, 2, 2, 2,                        /* 00 .. 07 */
-       3, 3, 3, 3, 3, 3, 3, 3,                 /* 08 .. 0f */
-       4, 4, 4, 4, 4, 4, 4, 4,                 /* 10 .. 17 */
-       4, 4, 4, 4, 4, 4, 4, 4,                 /* 18 .. 1f */
-       5, 5, 5, 5, 5, 5, 5, 5,                 /* 20 .. 27 */
-       5, 5, 5, 5, 5, 5, 5, 5,                 /* 28 .. 2f */
-       5, 5, 5, 5, 5, 5, 5, 5,                 /* 30 .. 37 */
-       5, 5, 5, 5, 5, 5, 5, 5,                 /* 38 .. 3f */
-       6, 6, 6, 6, 6, 6, 6, 6,                 /* 40 .. 47 */
-       6, 6, 6, 6, 6, 6, 6, 6,                 /* 48 .. 4f */
-       6, 6, 6, 6, 6, 6, 6, 6,                 /* 50 .. 57 */
-       6, 6, 6, 6, 6, 6, 6, 6,                 /* 58 .. 5f */
-       6, 6, 6, 6, 6, 6, 6, 6,                 /* 60 .. 67 */
-       6, 6, 6, 6, 6, 6, 6, 6,                 /* 68 .. 6f */
-       6, 6, 6, 6, 6, 6, 6, 6,                 /* 70 .. 77 */
-       6, 6, 6, 6, 6, 6, 6, 6,                 /* 78 .. 7f */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* 80 .. 87 */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* 88 .. 8f */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* 90 .. 97 */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* 98 .. 9f */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* a0 .. a7 */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* a8 .. af */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* b0 .. b7 */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* b8 .. bf */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* c0 .. c7 */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* c8 .. cf */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* d0 .. d7 */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* d8 .. df */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* e0 .. e7 */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* e8 .. ef */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* f0 .. f7 */
-       7, 7, 7, 7, 7, 7, 7, 7,                 /* f8 .. ff */
-};
-#endif
-
-/*
- * xfs_highbit32: get high bit set out of 32-bit argument, -1 if none set.
- */
-inline int
-xfs_highbit32(
-       __uint32_t      v)
-{
-#ifdef HAVE_ARCH_HIGHBIT
-       return highbit32(v);
-#else
-       int             i;
-
-       if (v & 0xffff0000)
-               if (v & 0xff000000)
-                       i = 24;
-               else
-                       i = 16;
-       else if (v & 0x0000ffff)
-               if (v & 0x0000ff00)
-                       i = 8;
-               else
-                       i = 0;
-       else
-               return -1;
-       return i + xfs_highbit[(v >> i) & 0xff];
-#endif
-}
-
-/*
- * xfs_lowbit64: get low bit set out of 64-bit argument, -1 if none set.
- */
-int
-xfs_lowbit64(
-       __uint64_t      v)
-{
-       __uint32_t      w = (__uint32_t)v;
-       int             n = 0;
-
-       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;
-}
-
-/*
- * xfs_highbit64: get high bit set out of 64-bit argument, -1 if none set.
- */
-int
-xfs_highbit64(
-       __uint64_t      v)
-{
-       __uint32_t      h = (__uint32_t)(v >> 32);
-
-       if (h)
-               return xfs_highbit32(h) + 32;
-       return xfs_highbit32((__uint32_t)v);
-}
-
-
 /*
  * Return whether bitmap is empty.
  * Size is number of words in the bitmap, which is padded to word boundary
Index: 2.6.x-xfs-new/fs/xfs/xfs_bit.h
===================================================================
--- 2.6.x-xfs-new.orig/fs/xfs/xfs_bit.h 2007-06-20 15:54:59.000000000 +1000
+++ 2.6.x-xfs-new/fs/xfs/xfs_bit.h      2007-10-05 09:07:20.574761334 +1000
@@ -47,13 +47,30 @@ static inline __uint64_t xfs_mask64lo(in
 }
 
 /* Get high bit set out of 32-bit argument, -1 if none set */
-extern int xfs_highbit32(__uint32_t v);
-
-/* Get low bit set out of 64-bit argument, -1 if none set */
-extern int xfs_lowbit64(__uint64_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 */
-extern int xfs_highbit64(__uint64_t);
+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 */
+static inline int xfs_lowbit64(__uint64_t v)
+{
+       unsigned long   t = v;
+       return (v) ? find_first_bit(&t, 64) : -1;
+}
 
 /* Return whether bitmap is empty (1 == empty) */
 extern int xfs_bitmap_empty(uint *map, uint size);
Index: 2.6.x-xfs-new/fs/xfs/xfs_rtalloc.c
===================================================================
--- 2.6.x-xfs-new.orig/fs/xfs/xfs_rtalloc.c     2007-08-24 22:24:45.000000000 
+1000
+++ 2.6.x-xfs-new/fs/xfs/xfs_rtalloc.c  2007-10-05 09:08:04.365058330 +1000
@@ -73,18 +73,6 @@ STATIC int xfs_rtmodify_summary(xfs_moun
  */
 
 /*
- * xfs_lowbit32: get low bit set out of 32-bit argument, -1 if none set.
- */
-STATIC int
-xfs_lowbit32(
-       __uint32_t      v)
-{
-       if (v)
-               return ffs(v) - 1;
-       return -1;
-}
-
-/*
  * Allocate space to the bitmap or summary file, and zero it, for growfs.
  */
 STATIC int                             /* error */
@@ -444,6 +432,7 @@ xfs_rtallocate_extent_near(
        }
        bbno = XFS_BITTOBLOCK(mp, bno);
        i = 0;
+       ASSERT(minlen != 0);
        log2len = xfs_highbit32(minlen);
        /*
         * Loop over all bitmap blocks (bbno + i is current block).
@@ -612,6 +601,8 @@ xfs_rtallocate_extent_size(
        xfs_suminfo_t   sum;            /* summary information for extents */
 
        ASSERT(minlen % prod == 0 && maxlen % prod == 0);
+       ASSERT(maxlen != 0);
+
        /*
         * Loop over all the levels starting with maxlen.
         * At each level, look at all the bitmap blocks, to see if there
@@ -669,6 +660,9 @@ xfs_rtallocate_extent_size(
                *rtblock = NULLRTBLOCK;
                return 0;
        }
+       ASSERT(minlen != 0);
+       ASSERT(maxlen != 0);
+
        /*
         * Loop over sizes, from maxlen down to minlen.
         * This time, when we do the allocations, allow smaller ones
@@ -1954,6 +1948,7 @@ xfs_growfs_rt(
                                  nsbp->sb_blocksize * nsbp->sb_rextsize);
                nsbp->sb_rextents = nsbp->sb_rblocks;
                do_div(nsbp->sb_rextents, nsbp->sb_rextsize);
+               ASSERT(nsbp->sb_rextents != 0);
                nsbp->sb_rextslog = xfs_highbit32(nsbp->sb_rextents);
                nrsumlevels = nmp->m_rsumlevels = nsbp->sb_rextslog + 1;
                nrsumsize =


<Prev in Thread] Current Thread [Next in Thread>