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ext4_bread

struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
			       ext4_lblk_t block, int map_flags)
{
	struct buffer_head *bh;


	bh = ext4_getblk(handle, inode, block, map_flags);
	if (IS_ERR(bh))
		return bh;
	if (!bh || buffer_uptodate(bh))
		return bh;
	ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1, &bh);
	wait_on_buffer(bh);
	if (buffer_uptodate(bh))
		return bh;
	put_bh(bh);
	return ERR_PTR(-EIO);
}