UBIFS: small amendments in the LEB scanning code

This patch fixes few minor things I've spotted while going through
code:

1. Better document return codes
2. If 'ubifs_scan_a_node()' returns some thing we do not expect,
   treat this as an error.
3. Try to do recovery only when 'ubifs_scan()' returns %-EUCLEAN,
   not on any error.
4. If empty space starts at a non-aligned address, print a message.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Reviewed-by: Adrian Hunter <Adrian.Hunter@nokia.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/fs/ubifs/scan.c b/fs/ubifs/scan.c
index 165c14b..892ebfe 100644
--- a/fs/ubifs/scan.c
+++ b/fs/ubifs/scan.c
@@ -256,7 +256,9 @@ void ubifs_scanned_corruption(const struct ubifs_info *c, int lnum, int offs,
  * @sbuf: scan buffer (must be c->leb_size)
  *
  * This function scans LEB number @lnum and returns complete information about
- * its contents. Returns an error code in case of failure.
+ * its contents. Returns the scaned information in case of success and,
+ * %-EUCLEAN if the LEB neads recovery, and other negative error codes in case
+ * of failure.
  */
 struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
 				  int offs, void *sbuf)
@@ -279,7 +281,6 @@ struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
 		cond_resched();
 
 		ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 0);
-
 		if (ret > 0) {
 			/* Padding bytes or a valid padding node */
 			offs += ret;
@@ -304,7 +305,8 @@ struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
 			goto corrupted;
 		default:
 			dbg_err("unknown");
-			goto corrupted;
+			err = -EINVAL;
+			goto error;
 		}
 
 		err = ubifs_add_snod(c, sleb, buf, offs);
@@ -317,8 +319,10 @@ struct ubifs_scan_leb *ubifs_scan(const struct ubifs_info *c, int lnum,
 		len -= node_len;
 	}
 
-	if (offs % c->min_io_size)
-		goto corrupted;
+	if (offs % c->min_io_size) {
+		ubifs_err("empty space starts at non-aligned offset %d", offs);
+		goto corrupted;;
+	}
 
 	ubifs_end_scan(c, sleb, lnum, offs);