From 24ad33ff714bd117cab30e71e2ad41e4e1185108 Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Thu, 28 Jun 2007 16:43:30 +1000 Subject: [PATCH] [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 Signed-off-by: David Chinner Signed-off-by: Tim Shimmin --- fs/xfs/xfs_bit.c | 91 +++++-------------------------------------- fs/xfs/xfs_bit.h | 4 +- fs/xfs/xfs_buf_item.c | 4 +- 3 files changed, 13 insertions(+), 86 deletions(-) diff --git a/fs/xfs/xfs_bit.c b/fs/xfs/xfs_bit.c index 1afe07f67e3..fab0b6d5a41 100644 --- 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; + uint i; + uint ret = 0; - 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); + for (i = 0; i < size; i++) { + ret |= map[i]; } - /* - * 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++; - } - - /* - * Count the bits in each byte until the end of the bitmap. - */ - while (bytep < end_map) { - bits += xfs_countbit[*bytep]; - bytep++; - } - - return (bits); + return (ret == 0); } /* diff --git a/fs/xfs/xfs_bit.h b/fs/xfs/xfs_bit.h index 0bbe5681754..082641a9782 100644 --- 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 6c1bddc04e3..b0667cb27d6 100644 --- 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;