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>

3 files changed, 17 insertions, 11 deletions

diff --git a/fs/ubifs/recovery.c b/fs/ubifs/recovery.c
index 805605250f12..093a1ecb700f 100644
--- a/fs/ubifs/recovery.c
+++ b/fs/ubifs/recovery.c
@@ -543,8 +543,8 @@ static int drop_incomplete_group(struct ubifs_scan_leb *sleb, int *offs)
  *
  * This function does a scan of a LEB, but caters for errors that might have
  * been caused by the unclean unmount from which we are attempting to recover.
- *
- * This function returns %0 on success and a negative error code on failure.
+ * Returns %0 in case of success, %-EUCLEAN if an unrecoverable corruption is
+ * found, and a negative error code in case of failure.
  */
 struct ubifs_scan_leb *ubifs_recover_leb(struct ubifs_info *c, int lnum,
                                          int offs, void *sbuf, int grouped)
@@ -643,7 +643,8 @@ struct ubifs_scan_leb *ubifs_recover_leb(struct ubifs_info *c, int lnum,
                         goto corrupted;
                 default:
                         dbg_err("unknown");
-                        goto corrupted;
+                        err = -EINVAL;
+                        goto error;
                 }
         }
 
diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c
index 769be42f39d6..2970500f32df 100644
--- a/fs/ubifs/replay.c
+++ b/fs/ubifs/replay.c
@@ -837,9 +837,10 @@ static int replay_log_leb(struct ubifs_info *c, int lnum, int offs, void *sbuf)
 
         dbg_mnt("replay log LEB %d:%d", lnum, offs);
         sleb = ubifs_scan(c, lnum, offs, sbuf);
-        if (IS_ERR(sleb)) {
-                if (c->need_recovery)
-                        sleb = ubifs_recover_log_leb(c, lnum, offs, sbuf);
+        if (IS_ERR(sleb) ) {
+                if (PTR_ERR(sleb) != -EUCLEAN || !c->need_recovery)
+                        return PTR_ERR(sleb);
+                sleb = ubifs_recover_log_leb(c, lnum, offs, sbuf);
                 if (IS_ERR(sleb))
                         return PTR_ERR(sleb);
         }
diff --git a/fs/ubifs/scan.c b/fs/ubifs/scan.c
index 165c14ba1a46..892ebfee4fe5 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);