f2fs: handle error from f2fs_iget_nowait

In case f2fs_iget_nowait returns error, it results in truncate_hole being
called with 'error' value as inode pointer. There is no check in truncate_hole
for valid inode, so it could result in crash due "invalid access to memory".
Avoid this by handling error condition properly.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

fs/f2fs/recovery.c

@@ -228,6 +228,9 @@ static void check_index_in_prev_nodes(struct f2fs_sb_info *sbi,
 
 	/* Deallocate previous index in the node page */
 	inode = f2fs_iget_nowait(sbi->sb, ino);
+	if (IS_ERR(inode))
+		return;
+
 	truncate_hole(inode, bidx, bidx + 1);
 	iput(inode);
 }