commit 6965031d331a642e31278fa1b5bd47f372ffdd5d
author Miklos Szeredi <miklos@szeredi.hu> Tue Aug 03 12:48:50 2010 +0200
committer Jens Axboe <jaxboe@fusionio.com> Sat Aug 07 18:52:56 2010 +0200
tree 403363107b75f4efedd877c75ed8099377d41ec7
parent 7901d14144311c930918b1222aae7611284c63eb

splice: fix misuse of SPLICE_F_NONBLOCK

SPLICE_F_NONBLOCK is clearly documented to only affect blocking on the
pipe.  In __generic_file_splice_read(), however, it causes an EAGAIN
if the page is currently being read.

This makes it impossible to write an application that only wants
failure if the pipe is full.  For example if the same process is
handling both ends of a pipe and isn't otherwise able to determine
whether a splice to the pipe will fill it or not.

We could make the read non-blocking on O_NONBLOCK or some other splice
flag, but for now this is the simplest fix.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>