Commit 5b9d31ae authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFSv4: Add a parameter to limit the number of retries after NFS4ERR_DELAY 



When using a 'softerr' mount, the NFSv4 client can get stuck waiting
forever while the server just returns NFS4ERR_DELAY. Among other things,
this causes the knfsd server threads to busy wait.
Add a parameter that tells the NFSv4 client how many times to retry
before giving up.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent 05d3ef8b

Documentation/admin-guide/kernel-parameters.txt

+7 −0
Original line number Diff line number Diff line
@@ -3533,6 +3533,13 @@ 
			[NFS] set the TCP port on which the NFSv4 callback

			channel should listen.



	nfs.delay_retrans=

			[NFS] specifies the number of times the NFSv4 client

			retries the request before returning an EAGAIN error,

			after a reply of NFS4ERR_DELAY from the server.

			Only applies if the softerr mount option is enabled,

			and the specified value is >= 0.



	nfs.enable_ino64=

			[NFS] enable 64-bit inode numbers.

			If zero, the NFS client will fake up a 32-bit inode

fs/nfs/nfs4_fs.h

+2 −0
Original line number Diff line number Diff line
@@ -209,6 +209,7 @@ struct nfs4_exception { 
	struct inode *inode;

	nfs4_stateid *stateid;

	long timeout;

	unsigned short retrans;

	unsigned char task_is_privileged : 1;

	unsigned char delay : 1,

		      recovering : 1,
@@ -546,6 +547,7 @@ extern unsigned short max_session_slots; 
extern unsigned short max_session_cb_slots;

extern unsigned short send_implementation_id;

extern bool recover_lost_locks;

extern short nfs_delay_retrans;



#define NFS4_CLIENT_ID_UNIQ_LEN		(64)

extern char nfs4_client_id_uniquifier[NFS4_CLIENT_ID_UNIQ_LEN];

fs/nfs/nfs4proc.c

+25 −0
Original line number Diff line number Diff line
@@ -585,6 +585,21 @@ static int nfs4_do_handle_exception(struct nfs_server *server, 
	return 0;

}



/*

 * Track the number of NFS4ERR_DELAY related retransmissions and return

 * EAGAIN if the 'softerr' mount option is set, and we've exceeded the limit

 * set by 'nfs_delay_retrans'.

 */

static int nfs4_exception_should_retrans(const struct nfs_server *server,

					 struct nfs4_exception *exception)

{

	if (server->flags & NFS_MOUNT_SOFTERR && nfs_delay_retrans >= 0) {

		if (exception->retrans++ >= (unsigned short)nfs_delay_retrans)

			return -EAGAIN;

	}

	return 0;

}



/* This is the error handling routine for processes that are allowed

 * to sleep.

 */
@@ -595,6 +610,11 @@ int nfs4_handle_exception(struct nfs_server *server, int errorcode, struct nfs4_ 


	ret = nfs4_do_handle_exception(server, errorcode, exception);

	if (exception->delay) {

		int ret2 = nfs4_exception_should_retrans(server, exception);

		if (ret2 < 0) {

			exception->retry = 0;

			return ret2;

		}

		ret = nfs4_delay(&exception->timeout,

				exception->interruptible);

		goto out_retry;
@@ -623,6 +643,11 @@ nfs4_async_handle_exception(struct rpc_task *task, struct nfs_server *server, 


	ret = nfs4_do_handle_exception(server, errorcode, exception);

	if (exception->delay) {

		int ret2 = nfs4_exception_should_retrans(server, exception);

		if (ret2 < 0) {

			exception->retry = 0;

			return ret2;

		}

		rpc_delay(task, nfs4_update_delay(&exception->timeout));

		goto out_retry;

	}

fs/nfs/super.c

+7 −1
Original line number Diff line number Diff line
@@ -1366,6 +1366,7 @@ unsigned short max_session_cb_slots = NFS4_DEF_CB_SLOT_TABLE_SIZE; 
unsigned short send_implementation_id = 1;

char nfs4_client_id_uniquifier[NFS4_CLIENT_ID_UNIQ_LEN] = "";

bool recover_lost_locks = false;

short nfs_delay_retrans = -1;



EXPORT_SYMBOL_GPL(nfs_callback_nr_threads);

EXPORT_SYMBOL_GPL(nfs_callback_set_tcpport);
@@ -1376,6 +1377,7 @@ EXPORT_SYMBOL_GPL(max_session_cb_slots); 
EXPORT_SYMBOL_GPL(send_implementation_id);

EXPORT_SYMBOL_GPL(nfs4_client_id_uniquifier);

EXPORT_SYMBOL_GPL(recover_lost_locks);

EXPORT_SYMBOL_GPL(nfs_delay_retrans);



#define NFS_CALLBACK_MAXPORTNR (65535U)
@@ -1424,5 +1426,9 @@ MODULE_PARM_DESC(recover_lost_locks, 
		 "If the server reports that a lock might be lost, "

		 "try to recover it risking data corruption.");





module_param_named(delay_retrans, nfs_delay_retrans, short, 0644);

MODULE_PARM_DESC(delay_retrans,

		 "Unless negative, specifies the number of times the NFSv4 "

		 "client retries a request before returning an EAGAIN error, "

		 "after a reply of NFS4ERR_DELAY from the server.");

#endif /* CONFIG_NFS_V4 */