From 06b155bff995fe13d68cc2829121d0d719e6fde7 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Sat, 9 Aug 2014 12:31:04 -0400
Subject: [PATCH 1/5] e2fsck: fix file systems with an overly large
 s_first_meta_bg

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 e2fsck/problem.c |  5 +++++
 e2fsck/problem.h |  3 +++
 e2fsck/super.c   | 12 ++++++++++++
 3 files changed, 20 insertions(+)

diff --git a/e2fsck/problem.c b/e2fsck/problem.c
index 2e41bb2e..6c7f514e 100644
--- a/e2fsck/problem.c
+++ b/e2fsck/problem.c
@@ -438,6 +438,11 @@ static struct e2fsck_problem problem_table[] = {
 	  N_("@S 64bit filesystems needs extents to access the whole disk.  "),
 	  PROMPT_FIX, PR_PREEN_OK | PR_NO_OK},
 
+	/* The first_meta_bg is too big */
+	{ PR_0_FIRST_META_BG_TOO_BIG,
+	  N_("First_meta_bg is too big.  (%N, max value %g).  "),
+	  PROMPT_CLEAR, 0 },
+
 	/* Meta_bg and resize_inode are not compatible, disable resize_inode*/
 	{ PR_0_DISABLE_RESIZE_INODE,
 	  N_("Resize_@i and meta_bg features are enabled. Those features are\n"
diff --git a/e2fsck/problem.h b/e2fsck/problem.h
index a591974e..2fc9be05 100644
--- a/e2fsck/problem.h
+++ b/e2fsck/problem.h
@@ -252,6 +252,9 @@ struct problem_context {
 /* 64bit is set but extents are not set. */
 #define PR_0_64BIT_WITHOUT_EXTENTS		0x000048
 
+/* The first_meta_bg is too big */
+#define PR_0_FIRST_META_BG_TOO_BIG		0x000049
+
 /* Meta_bg and resize_inode are not compatible, remove resize_inode*/
 #define PR_0_DISABLE_RESIZE_INODE		0x000051
 
diff --git a/e2fsck/super.c b/e2fsck/super.c
index 7e2c2e4f..7439d9d4 100644
--- a/e2fsck/super.c
+++ b/e2fsck/super.c
@@ -599,6 +599,18 @@ void check_super_block(e2fsck_t ctx)
 		ext2fs_mark_super_dirty(fs);
 	}
 
+	if ((fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) &&
+	    (fs->super->s_first_meta_bg > fs->desc_blocks)) {
+		pctx.group = fs->desc_blocks;
+		pctx.num = fs->super->s_first_meta_bg;
+		if (fix_problem(ctx, PR_0_FIRST_META_BG_TOO_BIG, &pctx)) {
+			fs->super->s_feature_incompat &=
+				~EXT2_FEATURE_INCOMPAT_META_BG;
+			fs->super->s_first_meta_bg = 0;
+			ext2fs_mark_super_dirty(fs);
+		}
+	}
+
 	/*
 	 * Verify the group descriptors....
 	 */
-- 
2.21.3