From 02cf01aea5af7a4d1a38045712fe11bffcc206b0 Mon Sep 17 00:00:00 2001
From: Jens Axboe <jens.axboe@oracle.com>
Date: Wed, 20 Feb 2008 10:34:51 +0100
Subject: [PATCH] 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: Johann Felix Soden <johfel@users.sourceforge.net>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/splice.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/fs/splice.c b/fs/splice.c
index 9b559ee711a8..0670c915cd35 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -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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