On Mon, 16 Mar 2015 14:32:26 -0400 Milosz Tanski [off-list ref] wrote:

+.BR pwritev2 ()
 can also fail for the same reasons as
 .BR lseek (2).
-Additionally, the following error is defined:
+Additionally, the following errors are defined:
+.TP
+.B EAGAIN
+The operation would block. This is possible if the file descriptor \fIfd\fP refers to a socket and has been marked nonblocking
+.RB ( O_NONBLOCK ),
+or the operation is a
+.BR preadv2
+and the \fIflags\fP argument is set to
+.BR RWF_NONBLOCK.

Can you please expand on this to describe the circumstances in which
pread2() returns -EAGAIN?  Let's fix up the short-read confusion.

And let's have a think about EAGAIN vs EWOULDBLOCK.