Re: [PATCH] udf: use ext2_find_next_bit

[Jan Kara <jack@suse.cz>]

On Tue 23-02-10 23:11:13, Akinobu Mita wrote:
> Use ext2_find_next_bit (generic_find_next_le_bit) to find the set bit
> in little endian bitmap region.
> 
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> Cc: Jan Kara <jack@suse.cz>
  I've looked at the code and I think this is wrong. UDF uses 1 for free
block in the bitmap and 0 for used one. So you need to use
generic_find_next_le_bit...
  Something like the patch below?

								Honza

-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR
---

>From bfc8c674188d4be5856e445f9b57e1b7a3dbff6d Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Wed, 24 Feb 2010 17:18:57 +0100
Subject: [PATCH] udf: Use generic function for bit searching

Use generic_find_next_le_bit to search for bits in bitmap so
that we don't duplicate code unnecessarily.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/udf/balloc.c |   51 ++-------------------------------------------------
 1 files changed, 2 insertions(+), 49 deletions(-)

diff --git a/fs/udf/balloc.c b/fs/udf/balloc.c
index 82372e3..f5ff06c 100644
--- a/fs/udf/balloc.c
+++ b/fs/udf/balloc.c
@@ -31,55 +31,8 @@
 #define udf_clear_bit(nr, addr) ext2_clear_bit(nr, addr)
 #define udf_set_bit(nr, addr) ext2_set_bit(nr, addr)
 #define udf_test_bit(nr, addr) ext2_test_bit(nr, addr)
-#define udf_find_first_one_bit(addr, size) find_first_one_bit(addr, size)
 #define udf_find_next_one_bit(addr, size, offset) \
-		find_next_one_bit(addr, size, offset)
-
-#define leBPL_to_cpup(x) leNUM_to_cpup(BITS_PER_LONG, x)
-#define leNUM_to_cpup(x, y) xleNUM_to_cpup(x, y)
-#define xleNUM_to_cpup(x, y) (le ## x ## _to_cpup(y))
-#define uintBPL_t uint(BITS_PER_LONG)
-#define uint(x) xuint(x)
-#define xuint(x) __le ## x
-
-static inline int find_next_one_bit(void *addr, int size, int offset)
-{
-	uintBPL_t *p = ((uintBPL_t *) addr) + (offset / BITS_PER_LONG);
-	int result = offset & ~(BITS_PER_LONG - 1);
-	unsigned long tmp;
-
-	if (offset >= size)
-		return size;
-	size -= result;
-	offset &= (BITS_PER_LONG - 1);
-	if (offset) {
-		tmp = leBPL_to_cpup(p++);
-		tmp &= ~0UL << offset;
-		if (size < BITS_PER_LONG)
-			goto found_first;
-		if (tmp)
-			goto found_middle;
-		size -= BITS_PER_LONG;
-		result += BITS_PER_LONG;
-	}
-	while (size & ~(BITS_PER_LONG - 1)) {
-		tmp = leBPL_to_cpup(p++);
-		if (tmp)
-			goto found_middle;
-		result += BITS_PER_LONG;
-		size -= BITS_PER_LONG;
-	}
-	if (!size)
-		return result;
-	tmp = leBPL_to_cpup(p);
-found_first:
-	tmp &= ~0UL >> (BITS_PER_LONG - size);
-found_middle:
-	return result + ffz(~tmp);
-}
-
-#define find_first_one_bit(addr, size)\
-	find_next_one_bit((addr), (size), 0)
+		generic_find_next_le_bit((unsigned long *)addr, size, offset)
 
 static int read_block_bitmap(struct super_block *sb,
 			     struct udf_bitmap *bitmap, unsigned int block,
@@ -356,7 +309,7 @@ repeat:
 				break;
 			}
 		} else {
-			bit = udf_find_next_one_bit((char *)bh->b_data,
+			bit = udf_find_next_one_bit(bh->b_data,
 						    sb->s_blocksize << 3,
 						    group_start << 3);
 			if (bit < sb->s_blocksize << 3)
-- 
1.6.4.2