address hfs on-disk corruption robustness review comments

Address Roman's review comments for the previously sent on-disk
corruption hfs robustness patch.

- use 0 as a failure value, rather than making a new macro HFS_BAD_KEYLEN,
  and use a switch statement instead of if's.

- Add new fail: target to __hfs_brec_find to skip assignments using bad
  values when exiting with a failure.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/hfs/bfind.c

@@ -52,9 +52,9 @@ int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd)
 		rec = (e + b) / 2;
 		len = hfs_brec_lenoff(bnode, rec, &off);
 		keylen = hfs_brec_keylen(bnode, rec);
-		if (keylen == HFS_BAD_KEYLEN) {
+		if (keylen == 0) {
 			res = -EINVAL;
-			goto done;
+			goto fail;
 		}
 		hfs_bnode_read(bnode, fd->key, off, keylen);
 		cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
@@ -71,9 +71,9 @@ int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd)
 	if (rec != e && e >= 0) {
 		len = hfs_brec_lenoff(bnode, e, &off);
 		keylen = hfs_brec_keylen(bnode, e);
-		if (keylen == HFS_BAD_KEYLEN) {
+		if (keylen == 0) {
 			res = -EINVAL;
-			goto done;
+			goto fail;
 		}
 		hfs_bnode_read(bnode, fd->key, off, keylen);
 	}
@@ -83,6 +83,7 @@ int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd)
 	fd->keylength = keylen;
 	fd->entryoffset = off + keylen;
 	fd->entrylength = len - keylen;
+fail:
 	return res;
 }
 
@@ -206,7 +207,7 @@ int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
 
 	len = hfs_brec_lenoff(bnode, fd->record, &off);
 	keylen = hfs_brec_keylen(bnode, fd->record);
-	if (keylen == HFS_BAD_KEYLEN) {
+	if (keylen == 0) {
 		res = -EINVAL;
 		goto out;
 	}

fs/hfs/brec.c

@@ -49,14 +49,14 @@ u16 hfs_brec_keylen(struct hfs_bnode *node, u16 rec)
 			if (retval > node->tree->max_key_len + 2) {
 				printk(KERN_ERR "hfs: keylen %d too large\n",
 					retval);
-				retval = HFS_BAD_KEYLEN;
+				retval = 0;
 			}
 		} else {
 			retval = (hfs_bnode_read_u8(node, recoff) | 1) + 1;
 			if (retval > node->tree->max_key_len + 1) {
 				printk(KERN_ERR "hfs: keylen %d too large\n",
 					retval);
-				retval = HFS_BAD_KEYLEN;
+				retval = 0;
 			}
 		}
 	}

fs/hfs/btree.c

@@ -81,16 +81,24 @@ struct hfs_btree *hfs_btree_open(struct super_block *sb, u32 id, btree_keycmp ke
 		goto fail_page;
 	if (!tree->node_count)
 		goto fail_page;
-	if ((id == HFS_EXT_CNID) && (tree->max_key_len != HFS_MAX_EXT_KEYLEN)) {
+	switch (id) {
+	case HFS_EXT_CNID:
+		if (tree->max_key_len != HFS_MAX_EXT_KEYLEN) {
 			printk(KERN_ERR "hfs: invalid extent max_key_len %d\n",
 				tree->max_key_len);
 			goto fail_page;
 		}
-	if ((id == HFS_CAT_CNID) && (tree->max_key_len != HFS_MAX_CAT_KEYLEN)) {
+		break;
+	case HFS_CAT_CNID:
+		if (tree->max_key_len != HFS_MAX_CAT_KEYLEN) {
 			printk(KERN_ERR "hfs: invalid catalog max_key_len %d\n",
 				tree->max_key_len);
 			goto fail_page;
 		}
+		break;
+	default:
+		BUG();
+	}
 
 	tree->node_size_shift = ffs(size) - 1;
 	tree->pages_per_bnode = (tree->node_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;

fs/hfs/hfs.h

@@ -28,8 +28,6 @@
 #define HFS_MAX_NAMELEN		128
 #define HFS_MAX_VALENCE		32767U
 
-#define HFS_BAD_KEYLEN		0xFF
-
 /* Meanings of the drAtrb field of the MDB,
  * Reference: _Inside Macintosh: Files_ p. 2-61
  */