From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
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: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
---
.../admin-guide/kernel-parameters.txt | 7 ++++++
fs/nfs/nfs4_fs.h | 2 ++
fs/nfs/nfs4proc.c | 25 +++++++++++++++++++
fs/nfs/super.c | 8 +++++-
4 files changed, 41 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 722b6eca2e93..62af591ee2ad 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3517,6 +3517,13 @@
[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
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 4c9f8bd866ab..29b91482e5f4 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -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];
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 832fa226b8f2..99c054a6c7b5 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -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;
}
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 2284f749d892..929e122ff34b 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -1368,6 +1368,7 @@ 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);
@@ -1378,6 +1379,7 @@ 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)
@@ -1426,5 +1428,9 @@ 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 */
--
2.41.0
