[PATCH 3/5] smb3: fix temporary data corruption in collapse range

[Matthew Wilcox]

On Tue, Aug 23, 2022 at 02:07:41PM +0100, David Howells wrote:
>  
> +	filemap_invalidate_lock(inode->i_mapping);
>  	filemap_write_and_wait(inode->i_mapping);
> +	truncate_pagecache_range(inode, off, old_eof);

It's a bit odd to writeback the entire file but then truncate only part
of it.  XFS does the same part:

        error = filemap_write_and_wait_range(inode->i_mapping, start, end);
        if (error)
                return error;
        truncate_pagecache_range(inode, start, end);

... and presumably, you'd also want the error check?

>  	rc = smb2_copychunk_range(xid, cfile, cfile, off + len,
> -				  i_size_read(inode) - off - len, off);
> +				  old_eof - off - len, off);