lkml.org 
[lkml]   [2022]   [Nov]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [Linux-cachefs] [PATCH v2 2/2] netfs: Fix dodgy maths
From


On 11/5/22 12:38 AM, David Howells wrote:
> Fix the dodgy maths in netfs_rreq_unlock_folios(). start_page could be
> inside the folio, in which case the calculation of pgpos will be come up
> with a negative number (though for the moment rreq->start is rounded down
> earlier and folios would have to get merged whilst locked)
>
> Alter how this works to just frame the tracking in terms of absolute file
> positions, rather than offsets from the start of the I/O request. This
> simplifies the maths and makes it easier to follow.
>
> Fix the issue by using folio_pos() and folio_size() to calculate the end
> position of the page.
>
> Fixes: 3d3c95046742 ("netfs: Provide readahead and readpage netfs helpers")
> Reported-by: Matthew Wilcox <willy@infradead.org>
> Signed-off-by: David Howells <dhowells@redhat.com>
> cc: Jeff Layton <jlayton@kernel.org>
> cc: linux-cachefs@redhat.com
> cc: linux-fsdevel@vger.kernel.org
> Link: https://lore.kernel.org/r/Y2SJw7w1IsIik3nb@casper.infradead.org/

Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>

--
Thanks,
Jingbo

\
 
 \ /
  Last update: 2022-11-09 06:36    [W:0.081 / U:0.644 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site