splice: only return -EAGAIN if there's hope of more data (02cf01ae) · Commits · 戴 / test

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:

Johann Felix Soden <johfel@users.sourceforge.net> Signed-off-by:

Jens Axboe <jens.axboe@oracle.com>

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;
		}
		}
		}

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