From ee1dde6b44b7f8e150e17fdc7d6eea156f8783c5 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 3 Aug 2010 12:48:50 +0200 Subject: [PATCH] splice: fix misuse of SPLICE_F_NONBLOCK commit 6965031d331a642e31278fa1b5bd47f372ffdd5d upstream. 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 Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- fs/splice.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-) diff --git a/fs/splice.c b/fs/splice.c index 7394e9e17534..e5efbb96d2bd 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -365,17 +365,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, * If the page isn't uptodate, we may need to start io on it */ if (!PageUptodate(page)) { - /* - * If in nonblock mode then dont block on waiting - * for an in-flight io page - */ - if (flags & SPLICE_F_NONBLOCK) { - if (!trylock_page(page)) { - error = -EAGAIN; - break; - } - } else - lock_page(page); + lock_page(page); /* * Page was truncated, or invalidated by the -- 2.34.1