diff options
Diffstat (limited to 'fs/minix/bitmap.c')
| -rw-r--r-- | fs/minix/bitmap.c | 41 |
1 files changed, 14 insertions, 27 deletions
diff --git a/fs/minix/bitmap.c b/fs/minix/bitmap.c index 7c82c29429d..ef175cb8cfd 100644 --- a/fs/minix/bitmap.c +++ b/fs/minix/bitmap.c @@ -16,39 +16,26 @@ #include <linux/bitops.h> #include <linux/sched.h> -static const int nibblemap[] = { 4,3,3,2,3,2,2,1,3,2,2,1,2,1,1,0 }; - static DEFINE_SPINLOCK(bitmap_lock); -static unsigned long count_free(struct buffer_head *map[], unsigned blocksize, __u32 numbits) +/* + * bitmap consists of blocks filled with 16bit words + * bit set == busy, bit clear == free + * endianness is a mess, but for counting zero bits it really doesn't matter... + */ +static __u32 count_free(struct buffer_head *map[], unsigned blocksize, __u32 numbits) { - unsigned i, j, sum = 0; - struct buffer_head *bh; - unsigned numblocks = minix_blocks_needed(numbits, blocksize); - - for (i=0; i<numblocks-1; i++) { - if (!(bh=map[i])) - return(0); - for (j=0; j<bh->b_size; j++) - sum += nibblemap[bh->b_data[j] & 0xf] - + nibblemap[(bh->b_data[j]>>4) & 0xf]; - } + __u32 sum = 0; + unsigned blocks = DIV_ROUND_UP(numbits, blocksize * 8); - if (numblocks==0 || !(bh=map[numblocks-1])) - return(0); - i = ((numbits - (numblocks-1) * bh->b_size * 8) / 16) * 2; - for (j=0; j<i; j++) { - sum += nibblemap[bh->b_data[j] & 0xf] - + nibblemap[(bh->b_data[j]>>4) & 0xf]; + while (blocks--) { + unsigned words = blocksize / 2; + __u16 *p = (__u16 *)(*map++)->b_data; + while (words--) + sum += 16 - hweight16(*p++); } - i = numbits%16; - if (i!=0) { - i = *(__u16 *)(&bh->b_data[j]) | ~((1<<i) - 1); - sum += nibblemap[i & 0xf] + nibblemap[(i>>4) & 0xf]; - sum += nibblemap[(i>>8) & 0xf] + nibblemap[(i>>12) & 0xf]; - } - return(sum); + return sum; } void minix_free_block(struct inode *inode, unsigned long block) |