linux-ext4 - [PATCH] resize2fs: clear uninit BG if allocating from new group

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Date:	Thu, 17 Sep 2015 17:42:18 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	linux-ext4@...r.kernel.org
Subject: [PATCH] resize2fs: clear uninit BG if allocating from new group

If resize2fs_get_alloc_block() allocates from a BLOCK_UNINIT
group, nothing clears the UNINIT flag, so it is skipped when we
go to write out modified bitmaps.  This leads to post-resize2fs
e2fsck errors; used blocks in UNINIT groups, not marked in the
block bitmap.

This shamelessly cuts & pastes clear_block_uninit() into
resize2fs.c, and my problem goes away.

Signed-off-by: Eric Sandeen <sandeen@...hat.com>
---

I've kind of lost the thread on resize2fs lately, so maybe this is
a hack job?  At least it highlights the issue, even if it's not
quite right.  Passes "make check" here and seems ok to me...

Thanks,
-Eric

diff --git a/resize/resize2fs.c b/resize/resize2fs.c
index 07c6a0c..0f202bd 100644
--- a/resize/resize2fs.c
+++ b/resize/resize2fs.c
@@ -1614,12 +1614,27 @@ static blk64_t get_new_block(ext2_resize_t rfs)
 	}
 }
 
+static void clear_block_uninit(ext2_filsys fs, dgrp_t group)
+{
+	if (!ext2fs_has_group_desc_csum(fs) ||
+	    !(ext2fs_bg_flags_test(fs, group, EXT2_BG_BLOCK_UNINIT)))
+		return;
+
+	/* uninit block bitmaps are now initialized in read_bitmaps() */
+
+	ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
+	ext2fs_group_desc_csum_set(fs, group);
+	ext2fs_mark_super_dirty(fs);
+	ext2fs_mark_bb_dirty(fs);
+}
+
 static errcode_t resize2fs_get_alloc_block(ext2_filsys fs,
 					   blk64_t goal EXT2FS_ATTR((unused)),
 					   blk64_t *ret)
 {
 	ext2_resize_t rfs = (ext2_resize_t) fs->priv_data;
 	blk64_t blk;
+	int group;
 
 	blk = get_new_block(rfs);
 	if (!blk)
@@ -1632,6 +1647,12 @@ static errcode_t resize2fs_get_alloc_block(ext2_filsys fs,
 
 	ext2fs_mark_block_bitmap2(rfs->old_fs->block_map, blk);
 	ext2fs_mark_block_bitmap2(rfs->new_fs->block_map, blk);
+
+	group = ext2fs_group_of_blk2(rfs->old_fs, blk);
+	clear_block_uninit(rfs->old_fs, group);
+	group = ext2fs_group_of_blk2(rfs->new_fs, blk);
+	clear_block_uninit(rfs->new_fs, group);
+
 	*ret = (blk64_t) blk;
 	return 0;
 }

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