If an NFS server returns more than a few EJUKEBOX errors for a given RPC

request, the FreeBSD NFS client will quickly back off to a excessively
long wait (days, then weeks) before retrying the request.

Change the behavior of the FreeBSD NFS client to match the behavior of
the reference NFS client implementation (Solaris).  This provides a fixed
delay of 10 seconds between each retry by default.  A sysctl, called
nfs3_jukebox_delay, is now available to tune the delay.  Unlike Solaris,
the sysctl value on FreeBSD is in seconds, rather than in HZ.

Sponsored by:	Network Appliance, Incorporated
Reviewed by:	rick
Approved by:	silby
MFC after:	3 days

1 files changed, 4 insertions, 8 deletions

diff --git a/sys/nfsclient/nfs_socket.c b/sys/nfsclient/nfs_socket.c
index 9071ec9..27f047b 100644
--- a/sys/nfsclient/nfs_socket.c
+++ b/sys/nfsclient/nfs_socket.c
@@ -115,6 +115,7 @@ static int	nfs_realign_test;
 static int	nfs_realign_count;
 static int	nfs_bufpackets = 4;
 static int	nfs_reconnects;
+static int	nfs3_jukebox_delay = 10;
 
 SYSCTL_DECL(_vfs_nfs);
 
@@ -123,6 +124,8 @@ SYSCTL_INT(_vfs_nfs, OID_AUTO, realign_count, CTLFLAG_RW, &nfs_realign_count, 0,
 SYSCTL_INT(_vfs_nfs, OID_AUTO, bufpackets, CTLFLAG_RW, &nfs_bufpackets, 0, "");
 SYSCTL_INT(_vfs_nfs, OID_AUTO, reconnects, CTLFLAG_RD, &nfs_reconnects, 0,
     "number of times the nfs client has had to reconnect");
+SYSCTL_INT(_vfs_nfs, OID_AUTO, nfs3_jukebox_delay, CTLFLAG_RW, &nfs3_jukebox_delay, 0,
+    "number of seconds to delay a retry after receiving EJUKEBOX");
 
 
 /*
@@ -907,9 +910,6 @@ nfs_clnt_udp_soupcall(struct socket *so, void *arg, int waitflag)
  *	  by mrep or error
  * nb: always frees up mreq mbuf list
  */
-/* XXX overloaded before */
-#define	NQ_TRYLATERDEL	15	/* Initial try later delay (sec) */
-
 int
 nfs_request(struct vnode *vp, struct mbuf *mrest, int procnum,
     struct thread *td, struct ucred *cred, struct mbuf **mrp,
@@ -924,7 +924,6 @@ nfs_request(struct vnode *vp, struct mbuf *mrest, int procnum,
 	time_t waituntil;
 	caddr_t dpos;
 	int s, error = 0, mrest_len, auth_len, auth_type;
-	int trylater_delay = NQ_TRYLATERDEL, trylater_cnt = 0;
 	struct timeval now;
 	u_int32_t *xidp;
 
@@ -1123,13 +1122,10 @@ tryagain:
 				error == NFSERR_TRYLATER) {
 				m_freem(mrep);
 				error = 0;
-				waituntil = time_second + trylater_delay;
+				waituntil = time_second + nfs3_jukebox_delay;
 				while (time_second < waituntil)
 					(void) tsleep(&lbolt,
 						PSOCK, "nqnfstry", 0);
-				trylater_delay *= nfs_backoff[trylater_cnt];
-				if (trylater_cnt < NFS_NBACKOFF - 1)
-					trylater_cnt++;
 				if (++nfs_xid == 0)
 					nfs_xid++;
 				rep->r_xid = *xidp = txdr_unsigned(nfs_xid);