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Commit 02cf01ae authored by Jens Axboe's avatar Jens Axboe Committed by Jens Axboe
Browse files

splice: only return -EAGAIN if there's hope of more data 



sys_tee() currently is a bit eager in returning -EAGAIN, it may do so
even if we don't have a chance of anymore data becoming available. So
improve the logic and only return -EAGAIN if we have an attached writer
to the input pipe.

Reported by Johann Felix Soden <johfel@gmx.de> and
Patrick McManus <mcmanus@ducksong.com>.

Tested-by: default avatarJohann Felix Soden <johfel@users.sourceforge.net>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 5d87a052

fs/splice.c

+8 −4
Original line number Diff line number Diff line
@@ -1669,6 +1669,13 @@ static int link_pipe(struct pipe_inode_info *ipipe, 
		i++;

	} while (len);



	/*

	 * return EAGAIN if we have the potential of some data in the

	 * future, otherwise just return 0

	 */

	if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK))

		ret = -EAGAIN;



	inode_double_unlock(ipipe->inode, opipe->inode);



	/*
@@ -1709,11 +1716,8 @@ static long do_tee(struct file *in, struct file *out, size_t len, 
		ret = link_ipipe_prep(ipipe, flags);

		if (!ret) {

			ret = link_opipe_prep(opipe, flags);

			if (!ret) {

			if (!ret)

				ret = link_pipe(ipipe, opipe, len, flags);

				if (!ret && (flags & SPLICE_F_NONBLOCK))

					ret = -EAGAIN;

			}

		}

	}