linux-ext4 - [PATCH] e2fsck: remove resize inode if both resize_inode and meta

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Date:   Wed,  8 Aug 2018 13:52:56 +0200
From:   Lukas Czerner <lczerner@...hat.com>
To:     linux-ext4@...r.kernel.org
Cc:     Lukas Czerner <lczerner@...hat.com>
Subject: [PATCH] e2fsck: remove resize inode if both resize_inode and meta_bg are enabled

Previous e2fsprogs versions allowed to create a file system with both
resize_inode and meta_bg enabled. This was fixed by upstream commit
42e77d5d ("libext2fs: don't create filesystems with meta_bg and resize_inode")

However e2fsck still does not recognize the conflict and will attempt to
clear and recreate resize_inode if it's corrupted due to this incompatible
feature combination, though it will create it in the same wrong layout.

Fix it by teaching e2fsck to recognize resize_inode and meta_bg
conflict and fixing it by disabling and clearing resize inode.

Signed-off-by: Lukas Czerner <lczerner@...hat.com>
---
 e2fsck/problem.c | 6 ++++++
 e2fsck/problem.h | 3 +++
 e2fsck/super.c   | 8 ++++++++
 3 files changed, 17 insertions(+)

diff --git a/e2fsck/problem.c b/e2fsck/problem.c
index a0a3cfec..e439539e 100644
--- a/e2fsck/problem.c
+++ b/e2fsck/problem.c
@@ -339,6 +339,12 @@ static struct e2fsck_problem problem_table[] = {
 	  N_("Resize @i not valid.  "),
 	  PROMPT_RECREATE, 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"
+	     "not compatible. Resize @i should be disabled.  "),
+	  PROMPT_FIX, 0 },
+
 	/* Superblock last mount time is in the future */
 	{ PR_0_FUTURE_SB_LAST_MOUNT,
 	  N_("@S last mount time (%t,\n\tnow = %T) is in the future.\n"),
diff --git a/e2fsck/problem.h b/e2fsck/problem.h
index 7db122ab..2c79169e 100644
--- a/e2fsck/problem.h
+++ b/e2fsck/problem.h
@@ -285,6 +285,9 @@ struct problem_context {
 /* Inode count in the superblock incorrect */
 #define PR_0_INODE_COUNT_BIG			0x000050
 
+/* Meta_bg and resize_inode are not compatible, remove resize_inode*/
+#define PR_0_DISABLE_RESIZE_INODE		0x000051
+
 /*
  * Pass 1 errors
  */
diff --git a/e2fsck/super.c b/e2fsck/super.c
index eb7ab0d1..e5932be6 100644
--- a/e2fsck/super.c
+++ b/e2fsck/super.c
@@ -436,6 +436,14 @@ void check_resize_inode(e2fsck_t ctx)
 
 	clear_problem_context(&pctx);
 
+	if (ext2fs_has_feature_resize_inode(fs->super) &&
+	    ext2fs_has_feature_meta_bg(fs->super) &&
+	    fix_problem(ctx, PR_0_DISABLE_RESIZE_INODE, &pctx)) {
+		ext2fs_clear_feature_resize_inode(fs->super);
+		fs->super->s_reserved_gdt_blocks = 0;
+		ext2fs_mark_super_dirty(fs);
+	}
+
 	/*
 	 * If the resize inode feature isn't set, then
 	 * s_reserved_gdt_blocks must be zero.
-- 
2.17.1