Re: [PATCH] ceph: fix write_begin optimization when write is beyond EOF

[Matthew Wilcox <willy@xxxxxxxxxxxxx>]

On Fri, Jun 11, 2021 at 03:59:04PM -0400, Jeff Layton wrote:
>  		if ((pos_in_page == 0 && len == PAGE_SIZE) ||
> -		    (pos >= i_size_read(inode)) ||
> +		    (index > (i_size_read(inode) / PAGE_SIZE)) ||

I think that wants to be ((i_size_read(inode) - 1) / PAGE_SIZE)

If your file is 4096 bytes long, that means bytes 0-4095 contain data.
Except that i_size can be 0, so ...

		if ((offset == 0 && len == PAGE_SIZE) || i_size == 0 ||
		    (index > (i_size - 1) / PAGE_SIZE) ||
		    (offset == 0 && pos + len >= i_size))
  			zero_user_segments(page, 0, pos_in_page,
  					   pos_in_page + len, PAGE_SIZE);