On Mon, Sep 17, 2007 at 11:23:46PM +0100, Nix wrote:
Actually, they're nothing to do with malloc failures--the message
printed here is misleading, and isn't even an error; it gets printed
whenever an upcall to mountd is made. The problem is almost certainly a
problem with kernel<->mountd communication--the kernel depends on mountd
to answer questions about exported filesystems as part of the fh_verify
code.
It's just a shot in the dark, but you might try the latest nfs-utils
(get the latest out of git://linux-nfs.org/nfs-utils if you're already
on the most recent your distro will give you). Or just apply the
following--which did fix a problem whose symptoms varied depending on
libc behavior.
If that doesn't work, I'd try
strace -s0 `pidof rpc.mountd`
and also look at the contents of /proc/net/rpc/nfsd.fh/contents.
--b.
commit dd087896285da9e160e13ee9f7d75381b67895e3
Author: J. Bruce Fields <bfields@citi.umich.edu>
Date: Thu Jul 26 16:30:46 2007 -0400
Use __fpurge to ensure single-line writes to cache files
On a recent Debian/Sid machine, I saw libc retrying stdio writes that
returned write errors. The result is that if an export downcall returns
an error (which it can in normal operation, since it currently
(incorrectly) returns -ENOENT on any negative downcall), then subsequent
downcalls will write multiple lines (including the original line that
received the error).
The result is that the server fails to respond to any rpc call that
refers to an unexported mount point (such as a readdir of a directory
containing such a mountpoint), so client commands hang.
I don't know whether this libc behavior is correct or expected, but it
seems safest to add the __fpurge() (suggested by Neil) to ensure data is
thrown away.
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
diff --git a/support/nfs/cacheio.c b/support/nfs/cacheio.c
index a76915b..9d271cd 100644
--- a/support/nfs/cacheio.c
+++ b/support/nfs/cacheio.c
@@ -17,6 +17,7 @@
#include <nfslib.h>
#include <stdio.h>
+#include <stdio_ext.h>
#include <ctype.h>
#include <unistd.h>
#include <sys/types.h>
@@ -111,7 +112,18 @@ void qword_printint(FILE *f, int num)
int qword_eol(FILE *f)
{
+ int err;
+
fprintf(f,"\n");
+ err = fflush(f);
+ /*
+ * We must send one line (and one line only) in a single write
+ * call. In case of a write error, libc may accumulate the
+ * unwritten data and try to write it again later, resulting in a
+ * multi-line write. So we must explicitly ask it to throw away
+ * any such cached data:
+ */
+ __fpurge(f);
return fflush(f);
}
-
