From ffe1b3f8483c96e85409e5ea5ed69ab98128a3a1 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 17 Dec 2012 16:19:09 -0500 Subject: [PATCH] mountd: fix checking for errors when exporting filesystems commit 5604b35a61e22930873ffc4e9971002f578e7978 nfs-utils: Increase the stdio file buffer size for procfs files changed writes to some sysfs files to be line buffered (_IOLBF) where they weren't before. While this probably makes sense, it introduced a bug. With fully buffered streams, you don't expect to get an error until you call fflush(). With line buffered streams you can get the error from fprintf() et al. qword_eol() only tests the return from fflush(), not from fprintf(). Consequently errors were not noticed. One result of this is that if you export, with crossmnt, a filesystem underneath which are mounted non-exportable filesystems (e.g. /proc) then an 'ls -l' on the client will block indefinitely waiting for a meaningful 'yes' or 'no' from the server, but will never get one. This patch changes qword_eol to test both fprintf and fflush. Acked-by: J. Bruce Fields Signed-off-by: NeilBrown Signed-off-by: Steve Dickson --- support/nfs/cacheio.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/support/nfs/cacheio.c b/support/nfs/cacheio.c index e641c45..61e07a8 100644 --- a/support/nfs/cacheio.c +++ b/support/nfs/cacheio.c @@ -162,11 +162,16 @@ int qword_eol(FILE *f) { int err; - fprintf(f,"\n"); - err = fflush(f); - if (err) { - xlog_warn("qword_eol: fflush failed: errno %d (%s)", + err = fprintf(f,"\n"); + if (err < 0) { + xlog_warn("qword_eol: fprintf failed: errno %d (%s)", errno, strerror(errno)); + } else { + err = fflush(f); + if (err) { + xlog_warn("qword_eol: fflush failed: errno %d (%s)", + errno, strerror(errno)); + } } /* * We must send one line (and one line only) in a single write -- 2.39.2