Hi Christoph, On 29 October 2017 at 10:41, Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > On Sun, Oct 29, 2017 at 10:40:23AM +0200, Christoph Hellwig wrote: >> Signed-off-by: Christoph Hellwig <hch@xxxxxx> >> --- >> man2/readv.2 | 19 +++++++++++++++++++ >> 1 file changed, 19 insertions(+) >> >> diff --git a/man2/readv.2 b/man2/readv.2 >> index 831cf6260..21d82849e 100644 >> --- a/man2/readv.2 >> +++ b/man2/readv.2 >> @@ -232,6 +232,25 @@ This flag is meaningful only for >> .BR pwritev2 (), >> and its effect applies only to the data range written by the system call. >> .\" commit e864f39569f4092c2b2bc72c773b6e486c7e3bd9 >> +.TP >> +.BR RWF_NOWAIT " (since Linux 4.14)" >> +Dot not wait for data when it cannot be instantly retreived. If this flag >> +is specified the >> +.BR preadv2 () >> +system call will return instantly when it would have to read data from >> +the backing storage or wait for a lock. Instead it will return -1 and set >> +.I errno >> +to >> +.BR EAGAIN >> +if no data could be read, or return less bytes than requested if some data >> +could be read. >> +This flag is meaningful only for >> +.BR preadv2 () >> +at the moment. >> +.\" commit 3239d834847627b6634a4139cf1dc58f6f137a46 >> +.\" commit 91f9943e1c7b6638f27312d03fe71fcc67b23571 > > The phrasing is a bit tortured ... try this: > > .TP > .BR RWF_NOWAIT " (since Linux 4.14)" > Do not wait for data which is not immediately available. > If this flag is specified the > .BR preadv2 () > system call will return instantly if it would have to read data from > the backing storage or wait for a lock. > If some data was successfully read, it will return the number of bytes read. > If no bytes were read, it will return -1 and set > .IR errno to > .BR EAGAIN . > This flag is meaningful only for > .BR preadv2 () > at the moment. > .\" commit 3239d834847627b6634a4139cf1dc58f6f137a46 > .\" commit 91f9943e1c7b6638f27312d03fe71fcc67b23571 What are your thoughts on Matthew's proposed rewording? Thanks, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
