ext4: pass a char * to ext4_count_free() instead of a buffer_head ptr

commit f6fb99ca upstream.

Make it possible for ext4_count_free to operate on buffers and not
just data in buffer_heads.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

fs/ext4/balloc.c

@@ -557,7 +557,8 @@ ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
 		if (bitmap_bh == NULL)
 			continue;
 
-		x = ext4_count_free(bitmap_bh, sb->s_blocksize);
+		x = ext4_count_free(bitmap_bh->b_data,
+				    EXT4_BLOCKS_PER_GROUP(sb) / 8);
 		printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
 			i, ext4_free_group_clusters(sb, gdp), x);
 		bitmap_count += x;

fs/ext4/bitmap.c

@@ -15,15 +15,13 @@
 
 static const int nibblemap[] = {4, 3, 3, 2, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 1, 0};
 
-unsigned int ext4_count_free(struct buffer_head *map, unsigned int numchars)
+unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
 {
 	unsigned int i, sum = 0;
 
-	if (!map)
-		return 0;
 	for (i = 0; i < numchars; i++)
-		sum += nibblemap[map->b_data[i] & 0xf] +
-			nibblemap[(map->b_data[i] >> 4) & 0xf];
+		sum += nibblemap[bitmap[i] & 0xf] +
+			nibblemap[(bitmap[i] >> 4) & 0xf];
 	return sum;
 }
 

fs/ext4/ext4.h

@@ -1757,7 +1757,7 @@ struct mmpd_data {
 # define NORET_AND	noreturn,
 
 /* bitmap.c */
-extern unsigned int ext4_count_free(struct buffer_head *, unsigned);
+extern unsigned int ext4_count_free(char *bitmap, unsigned numchars);
 
 /* balloc.c */
 extern unsigned int ext4_block_group(struct super_block *sb,

fs/ext4/ialloc.c

@@ -1057,7 +1057,8 @@ unsigned long ext4_count_free_inodes(struct super_block *sb)
 		if (!bitmap_bh)
 			continue;
 
-		x = ext4_count_free(bitmap_bh, EXT4_INODES_PER_GROUP(sb) / 8);
+		x = ext4_count_free(bitmap_bh->b_data,
+				    EXT4_INODES_PER_GROUP(sb) / 8);
 		printk(KERN_DEBUG "group %lu: stored = %d, counted = %lu\n",
 			(unsigned long) i, ext4_free_inodes_count(sb, gdp), x);
 		bitmap_count += x;