diff options
authorNeilBrown <>2012-12-17 16:19:09 -0500
committerSteve Dickson <>2012-12-17 16:33:17 -0500
commitffe1b3f8483c96e85409e5ea5ed69ab98128a3a1 (patch)
parent11d4f1d2feae160caa35c4eb8565c969dc16a24d (diff)
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 <>
1 files 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