patch-2.4.27 linux-2.4.27/fs/xfs/xfs_bit.c

• Lines: 137
• Date: 2004-08-07 16:26:06.111406646 -0700
• Orig file: linux-2.4.26/fs/xfs/xfs_bit.c
• Orig date: 2004-02-18 05:36:32.000000000 -0800

diff -urN linux-2.4.26/fs/xfs/xfs_bit.c linux-2.4.27/fs/xfs/xfs_bit.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2002 Silicon Graphics, Inc.  All Rights Reserved.
+ * Copyright (c) 2000-2004 Silicon Graphics, Inc.  All Rights Reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of version 2 of the GNU General Public License as
@@ -154,14 +154,17 @@
 xfs_lowbit64(
 	__uint64_t	v)
 {
-	int n;
-	n = ffs((unsigned)v);
-	if (n <= 0) {
-		n = ffs(v >> 32);
-		if (n >= 0)
-			n+=32;
+	__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 <= 0) ? n : n-1;
+	return n - 1;
 }
 
 /*
@@ -171,10 +174,11 @@
 xfs_highbit64(
 	__uint64_t	v)
 {
-	__uint32_t h = v >> 32;
+	__uint32_t	h = (__uint32_t)(v >> 32);
+
 	if (h)
 		return xfs_highbit32(h) + 32;
-	return xfs_highbit32((__u32)v);
+	return xfs_highbit32((__uint32_t)v);
 }
 
 
@@ -238,32 +242,33 @@
 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 +293,20 @@
 	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;
 }