lkml.org 
[lkml]   [2017]   [Jan]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: 4.9.0 regression in pipe-backed iov_iter with systemd-nspawn
On Fri, Jan 13, 2017 at 08:08:27PM +0000, Al Viro wrote:

> Because it's "truncate to size", not "throw everything up to that point
> out".
>
> We have some amount of data pushed into pipe (in this case - 0) and we
> have some buffers allocated by ..._get_pages() past the end of it.
> Some of that we want to keep (again, in this case - none) and have the next
> copy_to_iter() go after those, the rest we discard.

PS: 'size' argument of iov_iter_advance() is the second "some" in the
above - we tell it how much we want to advance by and everything past
that point is, in case of PIPE_ITER, discarded.

\
 
 \ /
  Last update: 2017-01-13 21:12    [W:0.105 / U:0.324 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site