Simple ext2fs allocation routine cleanups

[John Baldwin]

I have some small changes to ext2fs to use ffs() to simplify some of the 
allocation routines.  The changes compile, but I have not had time to generate 
a test ext2fs file system to run-test them.  If someone has some spare cycles 
to setup a test file system and try them out I would appreciate it.  Otherwise 
I will get to it eventually.  Given that this hasn't been run-tested yet, I 
would not recommend using it for a production ext2fs since it may completely 
trash the filesystem.

Index: ext2_alloc.c
===================================================================
--- ext2_alloc.c	(revision 218951)
+++ ext2_alloc.c	(working copy)
@@ -815,16 +815,12 @@
 		}
 	} 
 	i = start + len - loc;
-	map = ibp[i];
-	ipref = i * NBBY;
-	for (i = 1; i < (1 << NBBY); i <<= 1, ipref++) {
-		if ((map & i) == 0) {
-			goto gotit;
-		}
+	map = ibp[i] ^ 0xff;
+	if (map == 0) {
+		printf("fs = %s\n", fs->e2fs_fsmnt);
+		panic("ext2fs_nodealloccg: block not in map");
 	}
-	printf("fs = %s\n", fs->e2fs_fsmnt);
-	panic("ext2fs_nodealloccg: block not in map");
-	/* NOTREACHED */
+	ipref = i * NBBY + ffs(map);
 gotit:
 	setbit(ibp, ipref);
 	EXT2_LOCK(ump);
@@ -952,7 +948,6 @@
 static daddr_t
 ext2_mapsearch(struct m_ext2fs *fs, char *bbp, daddr_t bpref)
 {
-	daddr_t bno;
 	int start, len, loc, i, map;
 
 	/*
@@ -977,15 +972,12 @@
 		}
 	}
 	i = start + len - loc;
-	map = bbp[i];
-	bno = i * NBBY;
-	for (i = 1; i < (1 << NBBY); i <<= 1, bno++) {
-		if ((map & i) == 0)
-			return (bno);
+	map = bbp[i] ^ 0xff;
+	if (map == 0) {
+		printf("fs = %s\n", fs->e2fs_fsmnt);
+		panic("ext2fs_mapsearch: block not in map");
 	}
-	printf("fs = %s\n", fs->e2fs_fsmnt);
-	panic("ext2fs_mapsearch: block not in map");
-	/* NOTREACHED */
+	return (i * NBBY + ffs(map));
 }
 
 /*

-- 
John Baldwin