From febbc583319b567fe3d83e521cc2ace9be8d1501 Mon Sep 17 00:00:00 2001
 From: Benjamin Lim <jarsp.ctf@gmail.com>
 Date: Fri, 29 Mar 2019 07:29:45 -0400
 Subject: [PATCH] Fix ext4 block group descriptor sizing
 
 Ext4 allows for arbitrarily sized block group descriptors when 64-bit
 addressing is enabled, which was previously not properly supported. This
 patch dynamically allocates a chunk of memory of the correct size.
 
 Signed-off-by: Benjamin Lim <jarsp.ctf@gmail.com>
 Signed-off-by Ajay Kaher <akaher@vmware.com?
 
 ---
  fs/ext4/ext4_common.c | 19 +++++++++++++++----
  1 file changed, 15 insertions(+), 4 deletions(-)
 
 diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
 index feffbfa..464c33d 100644
 --- a/fs/ext4/ext4_common.c
 +++ b/fs/ext4/ext4_common.c
 @@ -1587,7 +1587,7 @@ static int ext4fs_blockgroup
  
  int ext4fs_read_inode(struct ext2_data *data, int ino, struct ext2_inode *inode)
  {
 -	struct ext2_block_group blkgrp;
 +	struct ext2_block_group *blkgrp;
  	struct ext2_sblock *sblock = &data->sblock;
  	struct ext_filesystem *fs = get_fs();
  	int log2blksz = get_fs()->dev_desc->log2blksz;
 @@ -1595,17 +1595,28 @@ int ext4fs_read_inode(struct ext2_data *data, int ino, struct ext2_inode *inode)
  	long int blkno;
  	unsigned int blkoff;
  
 +	/* Allocate blkgrp based on gdsize (for 64-bit support). */
 +	blkgrp = zalloc(get_fs()->gdsize);
 +	if (!blkgrp)
 +		return 0;
 +
  	/* It is easier to calculate if the first inode is 0. */
  	ino--;
  	status = ext4fs_blockgroup(data, ino / le32_to_cpu
 -				   (sblock->inodes_per_group), &blkgrp);
 -	if (status == 0)
 +				   (sblock->inodes_per_group), blkgrp);
 +	if (status == 0) {
 +		free(blkgrp);
  		return 0;
 +	}
  
  	inodes_per_block = EXT2_BLOCK_SIZE(data) / fs->inodesz;
 -	blkno = ext4fs_bg_get_inode_table_id(&blkgrp, fs) +
 +	blkno = ext4fs_bg_get_inode_table_id(blkgrp, fs) +
  	    (ino % le32_to_cpu(sblock->inodes_per_group)) / inodes_per_block;
  	blkoff = (ino % inodes_per_block) * fs->inodesz;
 +
 +	/* Free blkgrp as it is no longer required. */
 +	free(blkgrp);
 +
  	/* Read the inode. */
  	status = ext4fs_devread((lbaint_t)blkno << (LOG2_BLOCK_SIZE(data) -
  				log2blksz), blkoff,
 -- 
 2.7.4