commit f3745728bc254892da4c569ba3fd8801895f3524
Author: Eric Sandeen <sandeen@redhat.com>
Date:   Sun Mar 6 21:51:23 2016 -0500

    resize2fs: clear uninit BG if allocating from new group
    
    If resize2fs_get_alloc_block() allocates from a BLOCK_UNINIT group, we
    need to make sure that the UNINIT flag is cleared on both file system
    structures which are maintained by resize2fs.  This causes the
    modified bitmaps to not get written out, which leads to post-resize2fs
    e2fsck errors; used blocks in UNINIT groups, not marked in the block
    bitmap.  This was seen on r_ext4_small_bg.
    
    This patch uses clear_block_uninit() to clear the flag,
    and my problem goes away.
    
    Signed-off-by: Eric Sandeen <sandeen@redhat.com>
    Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
    Reviewed-by: Andreas Dilger <adilger@dilger.ca>
    Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Index: e2fsprogs-1.42.9/lib/ext2fs/alloc.c
===================================================================
--- e2fsprogs-1.42.9.orig/lib/ext2fs/alloc.c
+++ e2fsprogs-1.42.9/lib/ext2fs/alloc.c
@@ -27,6 +27,22 @@
 #include "ext2fs.h"
 
 /*
+ * Clear the uninit block bitmap flag if necessary
+ */
+void ext2fs_clear_block_uninit(ext2_filsys fs, dgrp_t group)
+{
+	if (!(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);
+}
+
+/*
  * Check for uninit block bitmaps and deal with them appropriately
  */
 static void check_block_uninit(ext2_filsys fs, ext2fs_block_bitmap map,
Index: e2fsprogs-1.42.9/lib/ext2fs/ext2fs.h
===================================================================
--- e2fsprogs-1.42.9.orig/lib/ext2fs/ext2fs.h
+++ e2fsprogs-1.42.9/lib/ext2fs/ext2fs.h
@@ -639,6 +639,7 @@ static inline int ext2fs_needs_large_fil
 }
 
 /* alloc.c */
+extern void ext2fs_clear_block_uninit(ext2_filsys fs, dgrp_t group);
 extern errcode_t ext2fs_new_inode(ext2_filsys fs, ext2_ino_t dir, int mode,
 				  ext2fs_inode_bitmap map, ext2_ino_t *ret);
 extern errcode_t ext2fs_new_block(ext2_filsys fs, blk_t goal,
Index: e2fsprogs-1.42.9/resize/resize2fs.c
===================================================================
--- e2fsprogs-1.42.9.orig/resize/resize2fs.c
+++ e2fsprogs-1.42.9/resize/resize2fs.c
@@ -1196,6 +1196,7 @@ static errcode_t resize2fs_get_alloc_blo
 {
 	ext2_resize_t rfs = (ext2_resize_t) fs->priv_data;
 	blk64_t blk;
+	int group;
 
 	blk = get_new_block(rfs);
 	if (!blk)
@@ -1208,6 +1209,12 @@ static errcode_t resize2fs_get_alloc_blo
 
 	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);
+	ext2fs_clear_block_uninit(rfs->old_fs, group);
+	group = ext2fs_group_of_blk2(rfs->new_fs, blk);
+	ext2fs_clear_block_uninit(rfs->new_fs, group);
+
 	*ret = (blk64_t) blk;
 	return 0;
 }