Simple ext2fs allocation routine cleanups

[John Baldwin]

On Wednesday, February 23, 2011 11:35:33 am gnehzuil gnehzuil wrote:
> Hi John,
> 
> I use dbench program to do some tests for your changes. However, it causes
> kernel crash. The error is as follows:
> 
> panic: __lockmgr_args: recursing on non recursive lockmgr ext2fs @
> /usr/src/sys/kern/vfs_subr.c:2124

I wasn't able to reproduce that, but I did have silly off-by-one bugs in the 
use of ffs() that should be fixed now:

Index: ext2_alloc.c
===================================================================
--- ext2_alloc.c	(revision 218975)
+++ ext2_alloc.c	(working copy)
@@ -815,16 +815,12 @@ ext2_nodealloccg(struct inode *ip, int cg, daddr_t
 		}
 	} 
 	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) - 1;
 gotit:
 	setbit(ibp, ipref);
 	EXT2_LOCK(ump);
@@ -952,7 +948,6 @@ ext2_vfree(pvp, ino, mode)
 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 @@ ext2_mapsearch(struct m_ext2fs *fs, char *bbp, dad
 		}
 	}
 	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) - 1);
 }
 
 /*

-- 
John Baldwin