splice: reinstate SIGPIPE/EPIPE handling

commit 52bce91165e5f2db422b2b972e83d389e5e4725c upstream.

Commit 8924feff66f3 ("splice: lift pipe_lock out of splice_to_pipe()")
caused a regression when there were no more readers left on a pipe that
was being spliced into: rather than the expected SIGPIPE and -EPIPE
return value, the writer would end up waiting forever for space to free
up (which obviously was not going to happen with no readers around).

Fixes: 8924feff66f3 ("splice: lift pipe_lock out of splice_to_pipe()")
Reported-and-tested-by: Andreas Schwab <schwab@linux-m68k.org>
Debugged-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/fs/splice.c b/fs/splice.c
index 5a7750bd2eea..63b8f54485dc 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1086,7 +1086,13 @@ EXPORT_SYMBOL(do_splice_direct);
 
 static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags)
 {
-        while (pipe->nrbufs == pipe->buffers) {
+        for (;;) {
+                if (unlikely(!pipe->readers)) {
+                        send_sig(SIGPIPE, current, 0);
+                        return -EPIPE;
+                }
+                if (pipe->nrbufs != pipe->buffers)
+                        return 0;
                 if (flags & SPLICE_F_NONBLOCK)
                         return -EAGAIN;
                 if (signal_pending(current))
@@ -1095,7 +1101,6 @@ static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags)
                 pipe_wait(pipe);
                 pipe->waiting_writers--;
         }
-        return 0;
 }
 
 static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,