patch-2_6_7-vs1_9_1_12

[linux-2.6.git] / fs / xfs / xfs_bit.c

diff --git a/fs/xfs/xfs_bit.c b/fs/xfs/xfs_bit.c
index 38fece1..ec12a13 100644 (file)
--- a/fs/xfs/xfs_bit.c
+++ b/fs/xfs/xfs_bit.c
@@ -238,32 +238,33 @@ xfs_count_bits(uint *map, uint size, uint start_bit)
 int
 xfs_contig_bits(uint *map, uint        size, uint start_bit)
 {
-#if BITS_PER_LONG == 32
-       return find_next_zero_bit((unsigned long *)map,
-                       size * sizeof(uint) * 8, start_bit) - start_bit;
-#else
-       /*
-        * The first argument to find_next_zero_bit needs to be aligned,
-        * but this is coming from the xfs_buf_log_format_t on-disk
-        * struct, which can't be padded or otherwise modified w/o breaking
-        * on-disk compatibility... so create a temporary, aligned
-        * variable, copy over the bitmap, and send that to find_next_zero_bit
-        * This only happens in recovery, so it's ugly but not too bad.
-        */
-       void * addr;
-       int bit;
-       size_t bitmap_size = size * sizeof(uint);
-
-       addr = (void *)kmem_alloc(bitmap_size, KM_SLEEP);
-       memcpy(addr, map, size * sizeof(uint));
-
-       bit = find_next_zero_bit((unsigned long *)addr,
-                       size * sizeof(uint) * 8, start_bit) - start_bit;
+       uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
+       uint result = 0;
+       uint tmp;
 
-       kmem_free(addr, bitmap_size);
+       size <<= BIT_TO_WORD_SHIFT;
 
-       return bit;
-#endif
+       ASSERT(start_bit < size);
+       size -= start_bit & ~(NBWORD - 1);
+       start_bit &= (NBWORD - 1);
+       if (start_bit) {
+               tmp = *p++;
+               /* set to one first offset bits prior to start */
+               tmp |= (~0U >> (NBWORD-start_bit));
+               if (tmp != ~0U)
+                       goto found;
+               result += NBWORD;
+               size -= NBWORD;
+       }
+       while (size) {
+               if ((tmp = *p++) != ~0U)
+                       goto found;
+               result += NBWORD;
+               size -= NBWORD;
+       }
+       return result - start_bit;
+found:
+       return result + ffz(tmp) - start_bit;
 }
 
 /*
@@ -288,25 +289,20 @@ int xfs_next_bit(uint *map, uint size, uint start_bit)
        start_bit &= (NBWORD - 1);
        if (start_bit) {
                tmp = *p++;
-               /* set to zero first offset bits */
+               /* set to zero first offset bits prior to start */
                tmp &= (~0U << start_bit);
-               if (size < NBWORD)
-                       goto found_first;
                if (tmp != 0U)
-                       goto found_middle;
-               size -= NBWORD;
+                       goto found;
                result += NBWORD;
+               size -= NBWORD;
        }
-       while (size >= NBWORD) {
+       while (size) {
                if ((tmp = *p++) != 0U)
-                       goto found_middle;
+                       goto found;
                result += NBWORD;
                size -= NBWORD;
        }
-       if (!size)
-               return -1;
-       tmp = *p;
-found_first:
-found_middle:
+       return -1;
+found:
        return result + ffs(tmp) - 1;
 }