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.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
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
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