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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>
hifive-unleashed-5.1
Jens Axboe 2008-02-20 10:34:51 +01:00 committed by Jens Axboe
parent 5d87a052c7
commit 02cf01aea5
1 changed files with 8 additions and 4 deletions
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12
fs/splice.c
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@ -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;
}
}
}