Hi Chuck, Bruce
This series of patches implement the NFSv4 Courteous Server.
A server which does not immediately expunge the state on lease expiration
is known as a Courteous Server. A Courteous Server continues to recognize
previously generated state tokens as valid until conflict arises between
the expired state and the requests from another client, or the server
reboots.
v2:
. add new callback, lm_expire_lock, to lock_manager_operations to
allow the lock manager to take appropriate action with conflict lock.
. handle conflicts of NFSv4 locks with NFSv3/NLM and local locks.
. expire courtesy client after 24hr if client has not reconnected.
. do not allow expired client to become courtesy client if there are
waiters for client's locks.
. modify client_info_show to show courtesy client and seconds from
last renew.
. fix a problem with NFSv4.1 server where the it keeps returning
SEQ4_STATUS_CB_PATH_DOWN in the successful SEQUENCE reply, after
the courtesy client reconnects, causing the client to keep sending
BCTS requests to server.
v3:
. modified posix_test_lock to check and resolve conflict locks
to handle NLM TEST and NFSv4 LOCKT requests.
. separate out fix for back channel stuck in SEQ4_STATUS_CB_PATH_DOWN.
v4:
. rework nfsd_check_courtesy to avoid dead lock of fl_lock and client_lock
by asking the laudromat thread to destroy the courtesy client.
. handle NFSv4 share reservation conflicts with courtesy client. This
includes conflicts between access mode and deny mode and vice versa.
. drop the patch for back channel stuck in SEQ4_STATUS_CB_PATH_DOWN.
v5:
. fix recursive locking of file_rwsem from posix_lock_file.
. retest with LOCKDEP enabled.
v6:
. merge witn 5.15-rc7
. fix a bug in nfs4_check_deny_bmap that did not check for matched
nfs4_file before checking for access/deny conflict. This bug causes
pynfs OPEN18 to fail since the server taking too long to release
lots of un-conflict clients' state.
. enhance share reservation conflict handler to handle case where
a large number of conflict courtesy clients need to be expired.
The 1st 100 clients are expired synchronously and the rest are
expired in the background by the laundromat and NFS4ERR_DELAY
is returned to the NFS client. This is needed to prevent the
NFS client from timing out waiting got the reply.
v7:
. Fix race condition in posix_test_lock and posix_lock_inode after
dropping spinlock.
. Enhance nfsd4_fl_expire_lock to work with with new lm_expire_lock
callback
. Always resolve share reservation conflicts asynchrously.
. Fix bug in nfs4_laundromat where spinlock is not used when
scanning cl_ownerstr_hashtbl.
. Fix bug in nfs4_laundromat where idr_get_next was called
with incorrect 'id'.
. Merge nfs4_destroy_courtesy_client into nfsd4_fl_expire_lock.
v8:
. Fix warning in nfsd4_fl_expire_lock reported by test robot.
v9:
. Simplify lm_expire_lock API by (1) remove the 'testonly' flag
and (2) specifying return value as true/false to indicate
whether conflict was succesfully resolved.
. Rework nfsd4_fl_expire_lock to mark client with
NFSD4_DESTROY_COURTESY_CLIENT then tell the laundromat to expire
the client in the background.
. Add a spinlock in nfs4_client to synchronize access to the
NFSD4_COURTESY_CLIENT and NFSD4_DESTROY_COURTESY_CLIENT flag to
handle race conditions when resolving lock and share reservation
conflict.
. Courtesy client that was marked as NFSD4_DESTROY_COURTESY_CLIENT
are now consisdered 'dead', waiting for the laundromat to expire
it. This client is no longer allowed to use its states if it
reconnects before the laundromat finishes expiring the client.
For v4.1 client, the detection is done in the processing of the
SEQUENCE op and returns NFS4ERR_BAD_SESSION to force the client
to re-establish new clientid and session.
For v4.0 client, the detection is done in the processing of the
RENEW and state-related ops and return NFS4ERR_EXPIRE to force
the client to re-establish new clientid.
v10:
Resolve deadlock in v9 by avoiding getting cl_client and
cl_cs_lock together. The laundromat needs to determine whether
the expired client has any state and also has no blockers on
its locks. Both of these conditions are allowed to change after
the laundromat transits an expired client to courtesy client.
When this happens, the laundromat will detect it on the next
run and and expire the courtesy client.
Remove client persistent record before marking it as COURTESY_CLIENT
and add client persistent record before clearing the COURTESY_CLIENT
flag to allow the courtesy client to transist to normal client to
continue to use its state.
Lock/delegation/share reversation conflict with courtesy client is
resolved by marking the courtesy client as DESTROY_COURTESY_CLIENT,
effectively disable it, then allow the current request to proceed
immediately.
Courtesy client marked as DESTROY_COURTESY_CLIENT is not allowed
to reconnect to reuse itsstate. It is expired by the laundromat
asynchronously in the background.
Move processing of expired clients from nfs4_laudromat to a
separate function, nfs4_get_client_reaplist, that creates the
reaplist and also to process courtesy clients.
Update Documentation/filesystems/locking.rst to include new
lm_lock_conflict call.
Modify leases_conflict to call lm_breaker_owns_lease only if
there is real conflict. This is to allow the lock manager to
resolve the delegation conflict if possible.
v11:
Add comment for lm_lock_conflict callback.
Replace static const courtesy_client_expiry with macro.
Remove courtesy_clnt argument from find_in_sessionid_hashtbl.
Callers use nfs4_client->cl_cs_client boolean to determined if
it's the courtesy client and take appropriate actions.
Rename NFSD4_COURTESY_CLIENT and NFSD4_DESTROY_COURTESY_CLIENT
with NFSD4_CLIENT_COURTESY and NFSD4_CLIENT_DESTROY_COURTESY.
v12:
Remove unnecessary comment in nfs4_get_client_reaplist.
Replace nfs4_client->cl_cs_client boolean with
NFSD4_CLIENT_COURTESY_CLNT flag.
Remove courtesy_clnt argument from find_client_in_id_table and
find_clp_in_name_tree. Callers use NFSD4_CLIENT_COURTESY_CLNT to
determined if it's the courtesy client and take appropriate actions.
v13:
Merge with 5.17-rc3.
Cleanup Documentation/filesystems/locking.rst: replace i_lock
with flc_lock, update API's that use flc_lock.
Rename lm_lock_conflict to lm_lock_expired().
Remove comment of lm_lock_expired API in lock_manager_operations.
Same information is in patch description.
Update commit messages of 4/4.
Add some comment for NFSD4_CLIENT_COURTESY_CLNT.
Add nfsd4_discard_courtesy_clnt() to eliminate duplicate code of
discarding courtesy client; setting NFSD4_DESTROY_COURTESY_CLIENT.
v14:
. merge with Chuck's public for-next branch.
. remove courtesy_client_expiry, use client's last renew time.
. simplify comment of nfs4_check_access_deny_bmap.
. add comment about race condition in nfs4_get_client_reaplist.
. add list_del when walking cslist in nfs4_get_client_reaplist.
. remove duplicate INIT_LIST_HEAD(&reaplist) from nfs4_laundromat
. Modify find_confirmed_client and find_confirmed_client_by_name
to detect courtesy client and destroy it.
. refactor lookup_clientid to use find_client_in_id_table
directly instead of find_confirmed_client.
. refactor nfsd4_setclientid to call find_clp_in_name_tree
directly instead of find_confirmed_client_by_name.
. remove comment of NFSD4_CLIENT_COURTESY.
. replace NFSD4_CLIENT_DESTROY_COURTESY with NFSD4_CLIENT_EXPIRED.
. replace NFSD4_CLIENT_COURTESY_CLNT with NFSD4_CLIENT_RECONNECTED.
v15:
. add helper locks_has_blockers_locked in fs.h to check for
lock blockers
. rename nfs4_conflict_clients to nfs4_resolve_deny_conflicts_locked
. update nfs4_upgrade_open() to handle courtesy clients.
. add helper nfs4_check_and_expire_courtesy_client and
nfs4_is_courtesy_client_expired to deduplicate some code.
. update nfs4_anylock_blocker:
. replace list_for_each_entry_safe with list_for_each_entry
. break nfs4_anylock_blocker into 2 smaller functions.
. update nfs4_get_client_reaplist:
. remove unnecessary commets
. acquire cl_cs_lock before setting NFSD4_CLIENT_COURTESY flag
. update client_info_show to show 'time since last renew: 00:00:38'
instead of 'seconds from last renew: 38'.
v16:
. update client_info_show to display 'status' as
'confirmed/unconfirmed/courtesy'
. replace helper locks_has_blockers_locked in fs.h in v15 with new
locks_owner_has_blockers call in fs/locks.c
. update nfs4_lockowner_has_blockers to use locks_owner_has_blockers
. move nfs4_check_and_expire_courtesy_client from 5/11 to 4/11
. remove unnecessary check for NULL clp in find_in_sessionid_hashtb
. fix typo in commit messages
v17:
. replace flags used for courtesy client with enum courtesy_client_state
. add state table in nfsd/state.h
. make nfsd4_expire_courtesy_clnt, nfsd4_discard_courtesy_clnt and
nfsd4_courtesy_clnt_expired as static inline.
. update nfsd_breaker_owns_lease to use dl->dl_stid.sc_client directly
. fix kernel test robot warning when CONFIG_FILE_LOCKING not defined.
v18:
. modify 0005-NFSD-Update-nfs4_get_vfs_file-to-handle-courtesy-cli.patch to:
. remove nfs4_check_access_deny_bmap, fold this functionality
into nfs4_resolve_deny_conflicts_locked by making use of
bmap_to_share_mode.
. move nfs4_resolve_deny_conflicts_locked into nfs4_file_get_access
and nfs4_file_check_deny.
v19:
. modify 0002-NFSD-Add-courtesy-client-state-macro-and-spinlock-to.patch to
. add NFSD4_CLIENT_ACTIVE
. redo Courtesy client state table
. modify 0007-NFSD-Update-find_in_sessionid_hashtbl-to-handle-cour.patch and
0008-NFSD-Update-find_client_in_id_table-to-handle-courte.patch to:
. set cl_cs_client_stare to NFSD4_CLIENT_ACTIVE when reactive
courtesy client
v20:
. modify 0006-NFSD-Update-find_clp_in_name_tree-to-handle-courtesy.patch to:
. add nfsd4_discard_reconnect_clnt
. replace call to nfsd4_discard_courtesy_clnt with
nfsd4_discard_reconnect_clnt
. modify 0007-NFSD-Update-find_in_sessionid_hashtbl-to-handle-cour.patch to:
. replace call to nfsd4_discard_courtesy_clnt with
nfsd4_discard_reconnect_clnt
. modify 0008-NFSD-Update-find_client_in_id_table-to-handle-courte.patch
. replace call to nfsd4_discard_courtesy_clnt with
nfsd4_discard_reconnect_clnt
Update find_clp_in_name_tree to check and expire courtesy client.
Update find_confirmed_client_by_name to discard the courtesy
client by setting CLIENT_EXPIRED.
Update nfsd4_setclientid to expire client with CLIENT_EXPIRED
state to prevent multiple confirmed clients with the same name
on the conf_name_tree.
Signed-off-by: Dai Ngo <[email protected]>
---
fs/nfsd/nfs4state.c | 25 ++++++++++++++++++++++---
fs/nfsd/state.h | 28 ++++++++++++++++++++++++++++
2 files changed, 50 insertions(+), 3 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index fe8969ba94b3..d14cea763511 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2893,8 +2893,11 @@ find_clp_in_name_tree(struct xdr_netobj *name, struct rb_root *root)
node = node->rb_left;
else if (cmp < 0)
node = node->rb_right;
- else
+ else {
+ if (nfsd4_courtesy_clnt_expired(clp))
+ return NULL;
return clp;
+ }
}
return NULL;
}
@@ -2973,8 +2976,13 @@ static bool clp_used_exchangeid(struct nfs4_client *clp)
static struct nfs4_client *
find_confirmed_client_by_name(struct xdr_netobj *name, struct nfsd_net *nn)
{
+ struct nfs4_client *clp;
+
lockdep_assert_held(&nn->client_lock);
- return find_clp_in_name_tree(name, &nn->conf_name_tree);
+ clp = find_clp_in_name_tree(name, &nn->conf_name_tree);
+ if (clp && nfsd4_discard_reconnect_clnt(clp))
+ clp = NULL;
+ return clp;
}
static struct nfs4_client *
@@ -4091,12 +4099,19 @@ nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
struct nfs4_client *unconf = NULL;
__be32 status;
struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
+ struct nfs4_client *cclient = NULL;
new = create_client(clname, rqstp, &clverifier);
if (new == NULL)
return nfserr_jukebox;
spin_lock(&nn->client_lock);
- conf = find_confirmed_client_by_name(&clname, nn);
+ /* find confirmed client by name */
+ conf = find_clp_in_name_tree(&clname, &nn->conf_name_tree);
+ if (conf && conf->cl_cs_client_state == NFSD4_CLIENT_RECONNECTED) {
+ cclient = conf;
+ conf = NULL;
+ }
+
if (conf && client_has_state(conf)) {
status = nfserr_clid_inuse;
if (clp_used_exchangeid(conf))
@@ -4127,7 +4142,11 @@ nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
new = NULL;
status = nfs_ok;
out:
+ if (cclient)
+ unhash_client_locked(cclient);
spin_unlock(&nn->client_lock);
+ if (cclient)
+ expire_client(cclient);
if (new)
free_client(new);
if (unconf) {
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index 8b81493ee48a..16167f223353 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -735,6 +735,7 @@ extern void nfsd4_client_record_remove(struct nfs4_client *clp);
extern int nfsd4_client_record_check(struct nfs4_client *clp);
extern void nfsd4_record_grace_done(struct nfsd_net *nn);
+/* courteous server */
static inline bool
nfsd4_expire_courtesy_clnt(struct nfs4_client *clp)
{
@@ -749,4 +750,31 @@ nfsd4_expire_courtesy_clnt(struct nfs4_client *clp)
return rc;
}
+static inline bool
+nfsd4_discard_reconnect_clnt(struct nfs4_client *clp)
+{
+ bool ret = false;
+
+ spin_lock(&clp->cl_cs_lock);
+ if (clp->cl_cs_client_state == NFSD4_CLIENT_RECONNECTED) {
+ clp->cl_cs_client_state = NFSD4_CLIENT_EXPIRED;
+ ret = true;
+ }
+ spin_unlock(&clp->cl_cs_lock);
+ return ret;
+}
+
+static inline bool
+nfsd4_courtesy_clnt_expired(struct nfs4_client *clp)
+{
+ bool rc = false;
+
+ spin_lock(&clp->cl_cs_lock);
+ if (clp->cl_cs_client_state == NFSD4_CLIENT_EXPIRED)
+ rc = true;
+ if (clp->cl_cs_client_state == NFSD4_CLIENT_COURTESY)
+ clp->cl_cs_client_state = NFSD4_CLIENT_RECONNECTED;
+ spin_unlock(&clp->cl_cs_lock);
+ return rc;
+}
#endif /* NFSD4_STATE_H */
--
2.9.5
Update client_info_show to show state of courtesy client
and time since last renew.
Signed-off-by: Dai Ngo <[email protected]>
---
fs/nfsd/nfs4state.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index edd50a4485aa..98557031c1ed 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2485,7 +2485,8 @@ static int client_info_show(struct seq_file *m, void *v)
{
struct inode *inode = m->private;
struct nfs4_client *clp;
- u64 clid;
+ u64 clid, hrs;
+ u32 mins, secs;
clp = get_nfsdfs_clp(inode);
if (!clp)
@@ -2493,10 +2494,17 @@ static int client_info_show(struct seq_file *m, void *v)
memcpy(&clid, &clp->cl_clientid, sizeof(clid));
seq_printf(m, "clientid: 0x%llx\n", clid);
seq_printf(m, "address: \"%pISpc\"\n", (struct sockaddr *)&clp->cl_addr);
- if (test_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags))
+
+ if (clp->cl_cs_client_state == NFSD4_CLIENT_COURTESY)
+ seq_puts(m, "status: courtesy\n");
+ else if (clp->cl_cs_client_state == NFSD4_CLIENT_CONFIRMED)
seq_puts(m, "status: confirmed\n");
else
seq_puts(m, "status: unconfirmed\n");
+ hrs = div_u64_rem(ktime_get_boottime_seconds() - clp->cl_time,
+ 3600, &secs);
+ mins = div_u64_rem((u64)secs, 60, &secs);
+ seq_printf(m, "time since last renew: %llu:%02u:%02u\n", hrs, mins, secs);
seq_printf(m, "name: ");
seq_quote_mem(m, clp->cl_name.data, clp->cl_name.len);
seq_printf(m, "\nminor version: %d\n", clp->cl_minorversion);
--
2.9.5
Update nfsd_breaker_owns_lease() to handle delegation conflict with
courtesy client by calling nfsd4_expire_courtesy_clnt.
Signed-off-by: Dai Ngo <[email protected]>
---
fs/nfsd/nfs4state.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 80772662236b..f20c75890594 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4727,6 +4727,9 @@ static bool nfsd_breaker_owns_lease(struct file_lock *fl)
struct svc_rqst *rqst;
struct nfs4_client *clp;
+ if (nfsd4_expire_courtesy_clnt(dl->dl_stid.sc_client))
+ return true;
+
if (!i_am_nfsd())
return false;
rqst = kthread_data(current);
--
2.9.5
Update find_in_sessionid_hashtbl to:
. skip client with CLIENT_EXPIRED state; discarded courtesy client.
. if courtesy client was found then set CLIENT_RECONNECTED so caller
can take appropriate action.
Update nfsd4_sequence and nfsd4_bind_conn_to_session to create client
record for courtesy client with CLIENT_RECONNECTED state.
Update nfsd4_destroy_session to discard courtesy client with
CLIENT_RECONNECTED state.
Signed-off-by: Dai Ngo <[email protected]>
---
fs/nfsd/nfs4state.c | 39 +++++++++++++++++++++++++++++++++++++--
1 file changed, 37 insertions(+), 2 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index d14cea763511..0fd058826e85 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -701,6 +701,22 @@ __nfs4_file_get_access(struct nfs4_file *fp, u32 access)
atomic_inc(&fp->fi_access[O_RDONLY]);
}
+static void
+nfsd4_reactivate_courtesy_client(struct nfs4_client *clp, __be32 status)
+{
+ spin_lock(&clp->cl_cs_lock);
+ if (clp->cl_cs_client_state == NFSD4_CLIENT_RECONNECTED) {
+ if (status == nfs_ok) {
+ clp->cl_cs_client_state = NFSD4_CLIENT_ACTIVE;
+ spin_unlock(&clp->cl_cs_lock);
+ nfsd4_client_record_create(clp);
+ return;
+ }
+ clp->cl_cs_client_state = NFSD4_CLIENT_EXPIRED;
+ }
+ spin_unlock(&clp->cl_cs_lock);
+}
+
/*
* Check if courtesy clients have conflicting access and resolve it if possible
*
@@ -1994,13 +2010,21 @@ find_in_sessionid_hashtbl(struct nfs4_sessionid *sessionid, struct net *net,
{
struct nfsd4_session *session;
__be32 status = nfserr_badsession;
+ struct nfs4_client *clp;
session = __find_in_sessionid_hashtbl(sessionid, net);
if (!session)
goto out;
+ clp = session->se_client;
+ if (nfsd4_courtesy_clnt_expired(clp)) {
+ session = NULL;
+ goto out;
+ }
status = nfsd4_get_session_locked(session);
- if (status)
+ if (status) {
session = NULL;
+ nfsd4_discard_reconnect_clnt(clp);
+ }
out:
*ret = status;
return session;
@@ -3700,6 +3724,7 @@ __be32 nfsd4_bind_conn_to_session(struct svc_rqst *rqstp,
struct nfsd4_session *session;
struct net *net = SVC_NET(rqstp);
struct nfsd_net *nn = net_generic(net, nfsd_net_id);
+ struct nfs4_client *clp;
if (!nfsd4_last_compound_op(rqstp))
return nfserr_not_only_op;
@@ -3732,6 +3757,8 @@ __be32 nfsd4_bind_conn_to_session(struct svc_rqst *rqstp,
nfsd4_init_conn(rqstp, conn, session);
status = nfs_ok;
out:
+ clp = session->se_client;
+ nfsd4_reactivate_courtesy_client(clp, status);
nfsd4_put_session(session);
out_no_session:
return status;
@@ -3754,6 +3781,7 @@ nfsd4_destroy_session(struct svc_rqst *r, struct nfsd4_compound_state *cstate,
int ref_held_by_me = 0;
struct net *net = SVC_NET(r);
struct nfsd_net *nn = net_generic(net, nfsd_net_id);
+ struct nfs4_client *clp;
status = nfserr_not_only_op;
if (nfsd4_compound_in_session(cstate, sessionid)) {
@@ -3766,6 +3794,11 @@ nfsd4_destroy_session(struct svc_rqst *r, struct nfsd4_compound_state *cstate,
ses = find_in_sessionid_hashtbl(sessionid, net, &status);
if (!ses)
goto out_client_lock;
+ clp = ses->se_client;
+ if (nfsd4_discard_reconnect_clnt(clp)) {
+ status = nfserr_badsession;
+ goto out_put_session;
+ }
status = nfserr_wrong_cred;
if (!nfsd4_mach_creds_match(ses->se_client, r))
goto out_put_session;
@@ -3870,7 +3903,7 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
struct nfsd4_compoundres *resp = rqstp->rq_resp;
struct xdr_stream *xdr = resp->xdr;
struct nfsd4_session *session;
- struct nfs4_client *clp;
+ struct nfs4_client *clp = NULL;
struct nfsd4_slot *slot;
struct nfsd4_conn *conn;
__be32 status;
@@ -3980,6 +4013,8 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
if (conn)
free_conn(conn);
spin_unlock(&nn->client_lock);
+ if (clp)
+ nfsd4_reactivate_courtesy_client(clp, status);
return status;
out_put_session:
nfsd4_put_session_locked(session);
--
2.9.5
I've got a process complaint here. Not a big deal, but I think we can
fix it and do a little better:
So, I appreciate that a big patch got split up. But we're not getting
all of the advantages of that, because what most of the patches do is
add new functions that don't actually have callers yet, or code that's
effectively dead until one of the last patches that actually tells the
laundromat to start transitioning clients to the courtesy state.
That means when reviewing these, I often have to look forward through
the patches to understand how the new code that's being added works.
Sometimes that's the best you can do. But I think we can order these so
that most of the patches actually make testable changes. That means
that if we introduce a bug, a bisect will land on the actual patch that
introduced the bug instead of a later patch that activated that code.
It also makes the patches easier to read in isolation.
I'll try to write up a suggestion.
--b.
On Wed, Apr 06, 2022 at 03:45:23PM -0700, Dai Ngo wrote:
> Hi Chuck, Bruce
>
> This series of patches implement the NFSv4 Courteous Server.
>
> A server which does not immediately expunge the state on lease expiration
> is known as a Courteous Server. A Courteous Server continues to recognize
> previously generated state tokens as valid until conflict arises between
> the expired state and the requests from another client, or the server
> reboots.
>
> v2:
>
> . add new callback, lm_expire_lock, to lock_manager_operations to
> allow the lock manager to take appropriate action with conflict lock.
>
> . handle conflicts of NFSv4 locks with NFSv3/NLM and local locks.
>
> . expire courtesy client after 24hr if client has not reconnected.
>
> . do not allow expired client to become courtesy client if there are
> waiters for client's locks.
>
> . modify client_info_show to show courtesy client and seconds from
> last renew.
>
> . fix a problem with NFSv4.1 server where the it keeps returning
> SEQ4_STATUS_CB_PATH_DOWN in the successful SEQUENCE reply, after
> the courtesy client reconnects, causing the client to keep sending
> BCTS requests to server.
>
> v3:
>
> . modified posix_test_lock to check and resolve conflict locks
> to handle NLM TEST and NFSv4 LOCKT requests.
>
> . separate out fix for back channel stuck in SEQ4_STATUS_CB_PATH_DOWN.
>
> v4:
>
> . rework nfsd_check_courtesy to avoid dead lock of fl_lock and client_lock
> by asking the laudromat thread to destroy the courtesy client.
>
> . handle NFSv4 share reservation conflicts with courtesy client. This
> includes conflicts between access mode and deny mode and vice versa.
>
> . drop the patch for back channel stuck in SEQ4_STATUS_CB_PATH_DOWN.
>
> v5:
>
> . fix recursive locking of file_rwsem from posix_lock_file.
>
> . retest with LOCKDEP enabled.
>
> v6:
>
> . merge witn 5.15-rc7
>
> . fix a bug in nfs4_check_deny_bmap that did not check for matched
> nfs4_file before checking for access/deny conflict. This bug causes
> pynfs OPEN18 to fail since the server taking too long to release
> lots of un-conflict clients' state.
>
> . enhance share reservation conflict handler to handle case where
> a large number of conflict courtesy clients need to be expired.
> The 1st 100 clients are expired synchronously and the rest are
> expired in the background by the laundromat and NFS4ERR_DELAY
> is returned to the NFS client. This is needed to prevent the
> NFS client from timing out waiting got the reply.
>
> v7:
>
> . Fix race condition in posix_test_lock and posix_lock_inode after
> dropping spinlock.
>
> . Enhance nfsd4_fl_expire_lock to work with with new lm_expire_lock
> callback
>
> . Always resolve share reservation conflicts asynchrously.
>
> . Fix bug in nfs4_laundromat where spinlock is not used when
> scanning cl_ownerstr_hashtbl.
>
> . Fix bug in nfs4_laundromat where idr_get_next was called
> with incorrect 'id'.
>
> . Merge nfs4_destroy_courtesy_client into nfsd4_fl_expire_lock.
>
> v8:
>
> . Fix warning in nfsd4_fl_expire_lock reported by test robot.
>
> v9:
>
> . Simplify lm_expire_lock API by (1) remove the 'testonly' flag
> and (2) specifying return value as true/false to indicate
> whether conflict was succesfully resolved.
>
> . Rework nfsd4_fl_expire_lock to mark client with
> NFSD4_DESTROY_COURTESY_CLIENT then tell the laundromat to expire
> the client in the background.
>
> . Add a spinlock in nfs4_client to synchronize access to the
> NFSD4_COURTESY_CLIENT and NFSD4_DESTROY_COURTESY_CLIENT flag to
> handle race conditions when resolving lock and share reservation
> conflict.
>
> . Courtesy client that was marked as NFSD4_DESTROY_COURTESY_CLIENT
> are now consisdered 'dead', waiting for the laundromat to expire
> it. This client is no longer allowed to use its states if it
> reconnects before the laundromat finishes expiring the client.
>
> For v4.1 client, the detection is done in the processing of the
> SEQUENCE op and returns NFS4ERR_BAD_SESSION to force the client
> to re-establish new clientid and session.
> For v4.0 client, the detection is done in the processing of the
> RENEW and state-related ops and return NFS4ERR_EXPIRE to force
> the client to re-establish new clientid.
>
> v10:
>
> Resolve deadlock in v9 by avoiding getting cl_client and
> cl_cs_lock together. The laundromat needs to determine whether
> the expired client has any state and also has no blockers on
> its locks. Both of these conditions are allowed to change after
> the laundromat transits an expired client to courtesy client.
> When this happens, the laundromat will detect it on the next
> run and and expire the courtesy client.
>
> Remove client persistent record before marking it as COURTESY_CLIENT
> and add client persistent record before clearing the COURTESY_CLIENT
> flag to allow the courtesy client to transist to normal client to
> continue to use its state.
>
> Lock/delegation/share reversation conflict with courtesy client is
> resolved by marking the courtesy client as DESTROY_COURTESY_CLIENT,
> effectively disable it, then allow the current request to proceed
> immediately.
>
> Courtesy client marked as DESTROY_COURTESY_CLIENT is not allowed
> to reconnect to reuse itsstate. It is expired by the laundromat
> asynchronously in the background.
>
> Move processing of expired clients from nfs4_laudromat to a
> separate function, nfs4_get_client_reaplist, that creates the
> reaplist and also to process courtesy clients.
>
> Update Documentation/filesystems/locking.rst to include new
> lm_lock_conflict call.
>
> Modify leases_conflict to call lm_breaker_owns_lease only if
> there is real conflict. This is to allow the lock manager to
> resolve the delegation conflict if possible.
>
> v11:
>
> Add comment for lm_lock_conflict callback.
>
> Replace static const courtesy_client_expiry with macro.
>
> Remove courtesy_clnt argument from find_in_sessionid_hashtbl.
> Callers use nfs4_client->cl_cs_client boolean to determined if
> it's the courtesy client and take appropriate actions.
>
> Rename NFSD4_COURTESY_CLIENT and NFSD4_DESTROY_COURTESY_CLIENT
> with NFSD4_CLIENT_COURTESY and NFSD4_CLIENT_DESTROY_COURTESY.
>
> v12:
>
> Remove unnecessary comment in nfs4_get_client_reaplist.
>
> Replace nfs4_client->cl_cs_client boolean with
> NFSD4_CLIENT_COURTESY_CLNT flag.
>
> Remove courtesy_clnt argument from find_client_in_id_table and
> find_clp_in_name_tree. Callers use NFSD4_CLIENT_COURTESY_CLNT to
> determined if it's the courtesy client and take appropriate actions.
>
> v13:
>
> Merge with 5.17-rc3.
>
> Cleanup Documentation/filesystems/locking.rst: replace i_lock
> with flc_lock, update API's that use flc_lock.
>
> Rename lm_lock_conflict to lm_lock_expired().
>
> Remove comment of lm_lock_expired API in lock_manager_operations.
> Same information is in patch description.
>
> Update commit messages of 4/4.
>
> Add some comment for NFSD4_CLIENT_COURTESY_CLNT.
>
> Add nfsd4_discard_courtesy_clnt() to eliminate duplicate code of
> discarding courtesy client; setting NFSD4_DESTROY_COURTESY_CLIENT.
>
> v14:
>
> . merge with Chuck's public for-next branch.
>
> . remove courtesy_client_expiry, use client's last renew time.
>
> . simplify comment of nfs4_check_access_deny_bmap.
>
> . add comment about race condition in nfs4_get_client_reaplist.
>
> . add list_del when walking cslist in nfs4_get_client_reaplist.
>
> . remove duplicate INIT_LIST_HEAD(&reaplist) from nfs4_laundromat
>
> . Modify find_confirmed_client and find_confirmed_client_by_name
> to detect courtesy client and destroy it.
>
> . refactor lookup_clientid to use find_client_in_id_table
> directly instead of find_confirmed_client.
>
> . refactor nfsd4_setclientid to call find_clp_in_name_tree
> directly instead of find_confirmed_client_by_name.
>
> . remove comment of NFSD4_CLIENT_COURTESY.
>
> . replace NFSD4_CLIENT_DESTROY_COURTESY with NFSD4_CLIENT_EXPIRED.
>
> . replace NFSD4_CLIENT_COURTESY_CLNT with NFSD4_CLIENT_RECONNECTED.
>
> v15:
>
> . add helper locks_has_blockers_locked in fs.h to check for
> lock blockers
>
> . rename nfs4_conflict_clients to nfs4_resolve_deny_conflicts_locked
>
> . update nfs4_upgrade_open() to handle courtesy clients.
>
> . add helper nfs4_check_and_expire_courtesy_client and
> nfs4_is_courtesy_client_expired to deduplicate some code.
>
> . update nfs4_anylock_blocker:
> . replace list_for_each_entry_safe with list_for_each_entry
> . break nfs4_anylock_blocker into 2 smaller functions.
>
> . update nfs4_get_client_reaplist:
> . remove unnecessary commets
> . acquire cl_cs_lock before setting NFSD4_CLIENT_COURTESY flag
>
> . update client_info_show to show 'time since last renew: 00:00:38'
> instead of 'seconds from last renew: 38'.
>
> v16:
>
> . update client_info_show to display 'status' as
> 'confirmed/unconfirmed/courtesy'
>
> . replace helper locks_has_blockers_locked in fs.h in v15 with new
> locks_owner_has_blockers call in fs/locks.c
>
> . update nfs4_lockowner_has_blockers to use locks_owner_has_blockers
>
> . move nfs4_check_and_expire_courtesy_client from 5/11 to 4/11
>
> . remove unnecessary check for NULL clp in find_in_sessionid_hashtb
>
> . fix typo in commit messages
>
> v17:
>
> . replace flags used for courtesy client with enum courtesy_client_state
>
> . add state table in nfsd/state.h
>
> . make nfsd4_expire_courtesy_clnt, nfsd4_discard_courtesy_clnt and
> nfsd4_courtesy_clnt_expired as static inline.
>
> . update nfsd_breaker_owns_lease to use dl->dl_stid.sc_client directly
>
> . fix kernel test robot warning when CONFIG_FILE_LOCKING not defined.
>
> v18:
>
> . modify 0005-NFSD-Update-nfs4_get_vfs_file-to-handle-courtesy-cli.patch to:
>
> . remove nfs4_check_access_deny_bmap, fold this functionality
> into nfs4_resolve_deny_conflicts_locked by making use of
> bmap_to_share_mode.
>
> . move nfs4_resolve_deny_conflicts_locked into nfs4_file_get_access
> and nfs4_file_check_deny.
>
> v19:
>
> . modify 0002-NFSD-Add-courtesy-client-state-macro-and-spinlock-to.patch to
>
> . add NFSD4_CLIENT_ACTIVE
>
> . redo Courtesy client state table
>
> . modify 0007-NFSD-Update-find_in_sessionid_hashtbl-to-handle-cour.patch and
> 0008-NFSD-Update-find_client_in_id_table-to-handle-courte.patch to:
>
> . set cl_cs_client_stare to NFSD4_CLIENT_ACTIVE when reactive
> courtesy client
>
> v20:
>
> . modify 0006-NFSD-Update-find_clp_in_name_tree-to-handle-courtesy.patch to:
> . add nfsd4_discard_reconnect_clnt
> . replace call to nfsd4_discard_courtesy_clnt with
> nfsd4_discard_reconnect_clnt
>
> . modify 0007-NFSD-Update-find_in_sessionid_hashtbl-to-handle-cour.patch to:
> . replace call to nfsd4_discard_courtesy_clnt with
> nfsd4_discard_reconnect_clnt
>
> . modify 0008-NFSD-Update-find_client_in_id_table-to-handle-courte.patch
> . replace call to nfsd4_discard_courtesy_clnt with
> nfsd4_discard_reconnect_clnt
On 4/8/22 9:39 AM, J. Bruce Fields wrote:
> I've got a process complaint here. Not a big deal, but I think we can
> fix it and do a little better:
>
> So, I appreciate that a big patch got split up. But we're not getting
> all of the advantages of that, because what most of the patches do is
> add new functions that don't actually have callers yet, or code that's
> effectively dead until one of the last patches that actually tells the
> laundromat to start transitioning clients to the courtesy state.
>
> That means when reviewing these, I often have to look forward through
> the patches to understand how the new code that's being added works.
>
> Sometimes that's the best you can do. But I think we can order these so
> that most of the patches actually make testable changes. That means
> that if we introduce a bug, a bisect will land on the actual patch that
> introduced the bug instead of a later patch that activated that code.
> It also makes the patches easier to read in isolation.
>
> I'll try to write up a suggestion.
Thank you Bruce, I'm looking forward to your suggestion.
-Dai
>
> --b.
>
> On Wed, Apr 06, 2022 at 03:45:23PM -0700, Dai Ngo wrote:
>> Hi Chuck, Bruce
>>
>> This series of patches implement the NFSv4 Courteous Server.
>>
>> A server which does not immediately expunge the state on lease expiration
>> is known as a Courteous Server. A Courteous Server continues to recognize
>> previously generated state tokens as valid until conflict arises between
>> the expired state and the requests from another client, or the server
>> reboots.
>>
>> v2:
>>
>> . add new callback, lm_expire_lock, to lock_manager_operations to
>> allow the lock manager to take appropriate action with conflict lock.
>>
>> . handle conflicts of NFSv4 locks with NFSv3/NLM and local locks.
>>
>> . expire courtesy client after 24hr if client has not reconnected.
>>
>> . do not allow expired client to become courtesy client if there are
>> waiters for client's locks.
>>
>> . modify client_info_show to show courtesy client and seconds from
>> last renew.
>>
>> . fix a problem with NFSv4.1 server where the it keeps returning
>> SEQ4_STATUS_CB_PATH_DOWN in the successful SEQUENCE reply, after
>> the courtesy client reconnects, causing the client to keep sending
>> BCTS requests to server.
>>
>> v3:
>>
>> . modified posix_test_lock to check and resolve conflict locks
>> to handle NLM TEST and NFSv4 LOCKT requests.
>>
>> . separate out fix for back channel stuck in SEQ4_STATUS_CB_PATH_DOWN.
>>
>> v4:
>>
>> . rework nfsd_check_courtesy to avoid dead lock of fl_lock and client_lock
>> by asking the laudromat thread to destroy the courtesy client.
>>
>> . handle NFSv4 share reservation conflicts with courtesy client. This
>> includes conflicts between access mode and deny mode and vice versa.
>>
>> . drop the patch for back channel stuck in SEQ4_STATUS_CB_PATH_DOWN.
>>
>> v5:
>>
>> . fix recursive locking of file_rwsem from posix_lock_file.
>>
>> . retest with LOCKDEP enabled.
>>
>> v6:
>>
>> . merge witn 5.15-rc7
>>
>> . fix a bug in nfs4_check_deny_bmap that did not check for matched
>> nfs4_file before checking for access/deny conflict. This bug causes
>> pynfs OPEN18 to fail since the server taking too long to release
>> lots of un-conflict clients' state.
>>
>> . enhance share reservation conflict handler to handle case where
>> a large number of conflict courtesy clients need to be expired.
>> The 1st 100 clients are expired synchronously and the rest are
>> expired in the background by the laundromat and NFS4ERR_DELAY
>> is returned to the NFS client. This is needed to prevent the
>> NFS client from timing out waiting got the reply.
>>
>> v7:
>>
>> . Fix race condition in posix_test_lock and posix_lock_inode after
>> dropping spinlock.
>>
>> . Enhance nfsd4_fl_expire_lock to work with with new lm_expire_lock
>> callback
>>
>> . Always resolve share reservation conflicts asynchrously.
>>
>> . Fix bug in nfs4_laundromat where spinlock is not used when
>> scanning cl_ownerstr_hashtbl.
>>
>> . Fix bug in nfs4_laundromat where idr_get_next was called
>> with incorrect 'id'.
>>
>> . Merge nfs4_destroy_courtesy_client into nfsd4_fl_expire_lock.
>>
>> v8:
>>
>> . Fix warning in nfsd4_fl_expire_lock reported by test robot.
>>
>> v9:
>>
>> . Simplify lm_expire_lock API by (1) remove the 'testonly' flag
>> and (2) specifying return value as true/false to indicate
>> whether conflict was succesfully resolved.
>>
>> . Rework nfsd4_fl_expire_lock to mark client with
>> NFSD4_DESTROY_COURTESY_CLIENT then tell the laundromat to expire
>> the client in the background.
>>
>> . Add a spinlock in nfs4_client to synchronize access to the
>> NFSD4_COURTESY_CLIENT and NFSD4_DESTROY_COURTESY_CLIENT flag to
>> handle race conditions when resolving lock and share reservation
>> conflict.
>>
>> . Courtesy client that was marked as NFSD4_DESTROY_COURTESY_CLIENT
>> are now consisdered 'dead', waiting for the laundromat to expire
>> it. This client is no longer allowed to use its states if it
>> reconnects before the laundromat finishes expiring the client.
>>
>> For v4.1 client, the detection is done in the processing of the
>> SEQUENCE op and returns NFS4ERR_BAD_SESSION to force the client
>> to re-establish new clientid and session.
>> For v4.0 client, the detection is done in the processing of the
>> RENEW and state-related ops and return NFS4ERR_EXPIRE to force
>> the client to re-establish new clientid.
>>
>> v10:
>>
>> Resolve deadlock in v9 by avoiding getting cl_client and
>> cl_cs_lock together. The laundromat needs to determine whether
>> the expired client has any state and also has no blockers on
>> its locks. Both of these conditions are allowed to change after
>> the laundromat transits an expired client to courtesy client.
>> When this happens, the laundromat will detect it on the next
>> run and and expire the courtesy client.
>>
>> Remove client persistent record before marking it as COURTESY_CLIENT
>> and add client persistent record before clearing the COURTESY_CLIENT
>> flag to allow the courtesy client to transist to normal client to
>> continue to use its state.
>>
>> Lock/delegation/share reversation conflict with courtesy client is
>> resolved by marking the courtesy client as DESTROY_COURTESY_CLIENT,
>> effectively disable it, then allow the current request to proceed
>> immediately.
>>
>> Courtesy client marked as DESTROY_COURTESY_CLIENT is not allowed
>> to reconnect to reuse itsstate. It is expired by the laundromat
>> asynchronously in the background.
>>
>> Move processing of expired clients from nfs4_laudromat to a
>> separate function, nfs4_get_client_reaplist, that creates the
>> reaplist and also to process courtesy clients.
>>
>> Update Documentation/filesystems/locking.rst to include new
>> lm_lock_conflict call.
>>
>> Modify leases_conflict to call lm_breaker_owns_lease only if
>> there is real conflict. This is to allow the lock manager to
>> resolve the delegation conflict if possible.
>>
>> v11:
>>
>> Add comment for lm_lock_conflict callback.
>>
>> Replace static const courtesy_client_expiry with macro.
>>
>> Remove courtesy_clnt argument from find_in_sessionid_hashtbl.
>> Callers use nfs4_client->cl_cs_client boolean to determined if
>> it's the courtesy client and take appropriate actions.
>>
>> Rename NFSD4_COURTESY_CLIENT and NFSD4_DESTROY_COURTESY_CLIENT
>> with NFSD4_CLIENT_COURTESY and NFSD4_CLIENT_DESTROY_COURTESY.
>>
>> v12:
>>
>> Remove unnecessary comment in nfs4_get_client_reaplist.
>>
>> Replace nfs4_client->cl_cs_client boolean with
>> NFSD4_CLIENT_COURTESY_CLNT flag.
>>
>> Remove courtesy_clnt argument from find_client_in_id_table and
>> find_clp_in_name_tree. Callers use NFSD4_CLIENT_COURTESY_CLNT to
>> determined if it's the courtesy client and take appropriate actions.
>>
>> v13:
>>
>> Merge with 5.17-rc3.
>>
>> Cleanup Documentation/filesystems/locking.rst: replace i_lock
>> with flc_lock, update API's that use flc_lock.
>>
>> Rename lm_lock_conflict to lm_lock_expired().
>>
>> Remove comment of lm_lock_expired API in lock_manager_operations.
>> Same information is in patch description.
>>
>> Update commit messages of 4/4.
>>
>> Add some comment for NFSD4_CLIENT_COURTESY_CLNT.
>>
>> Add nfsd4_discard_courtesy_clnt() to eliminate duplicate code of
>> discarding courtesy client; setting NFSD4_DESTROY_COURTESY_CLIENT.
>>
>> v14:
>>
>> . merge with Chuck's public for-next branch.
>>
>> . remove courtesy_client_expiry, use client's last renew time.
>>
>> . simplify comment of nfs4_check_access_deny_bmap.
>>
>> . add comment about race condition in nfs4_get_client_reaplist.
>>
>> . add list_del when walking cslist in nfs4_get_client_reaplist.
>>
>> . remove duplicate INIT_LIST_HEAD(&reaplist) from nfs4_laundromat
>>
>> . Modify find_confirmed_client and find_confirmed_client_by_name
>> to detect courtesy client and destroy it.
>>
>> . refactor lookup_clientid to use find_client_in_id_table
>> directly instead of find_confirmed_client.
>>
>> . refactor nfsd4_setclientid to call find_clp_in_name_tree
>> directly instead of find_confirmed_client_by_name.
>>
>> . remove comment of NFSD4_CLIENT_COURTESY.
>>
>> . replace NFSD4_CLIENT_DESTROY_COURTESY with NFSD4_CLIENT_EXPIRED.
>>
>> . replace NFSD4_CLIENT_COURTESY_CLNT with NFSD4_CLIENT_RECONNECTED.
>>
>> v15:
>>
>> . add helper locks_has_blockers_locked in fs.h to check for
>> lock blockers
>>
>> . rename nfs4_conflict_clients to nfs4_resolve_deny_conflicts_locked
>>
>> . update nfs4_upgrade_open() to handle courtesy clients.
>>
>> . add helper nfs4_check_and_expire_courtesy_client and
>> nfs4_is_courtesy_client_expired to deduplicate some code.
>>
>> . update nfs4_anylock_blocker:
>> . replace list_for_each_entry_safe with list_for_each_entry
>> . break nfs4_anylock_blocker into 2 smaller functions.
>>
>> . update nfs4_get_client_reaplist:
>> . remove unnecessary commets
>> . acquire cl_cs_lock before setting NFSD4_CLIENT_COURTESY flag
>>
>> . update client_info_show to show 'time since last renew: 00:00:38'
>> instead of 'seconds from last renew: 38'.
>>
>> v16:
>>
>> . update client_info_show to display 'status' as
>> 'confirmed/unconfirmed/courtesy'
>>
>> . replace helper locks_has_blockers_locked in fs.h in v15 with new
>> locks_owner_has_blockers call in fs/locks.c
>>
>> . update nfs4_lockowner_has_blockers to use locks_owner_has_blockers
>>
>> . move nfs4_check_and_expire_courtesy_client from 5/11 to 4/11
>>
>> . remove unnecessary check for NULL clp in find_in_sessionid_hashtb
>>
>> . fix typo in commit messages
>>
>> v17:
>>
>> . replace flags used for courtesy client with enum courtesy_client_state
>>
>> . add state table in nfsd/state.h
>>
>> . make nfsd4_expire_courtesy_clnt, nfsd4_discard_courtesy_clnt and
>> nfsd4_courtesy_clnt_expired as static inline.
>>
>> . update nfsd_breaker_owns_lease to use dl->dl_stid.sc_client directly
>>
>> . fix kernel test robot warning when CONFIG_FILE_LOCKING not defined.
>>
>> v18:
>>
>> . modify 0005-NFSD-Update-nfs4_get_vfs_file-to-handle-courtesy-cli.patch to:
>>
>> . remove nfs4_check_access_deny_bmap, fold this functionality
>> into nfs4_resolve_deny_conflicts_locked by making use of
>> bmap_to_share_mode.
>>
>> . move nfs4_resolve_deny_conflicts_locked into nfs4_file_get_access
>> and nfs4_file_check_deny.
>>
>> v19:
>>
>> . modify 0002-NFSD-Add-courtesy-client-state-macro-and-spinlock-to.patch to
>>
>> . add NFSD4_CLIENT_ACTIVE
>>
>> . redo Courtesy client state table
>>
>> . modify 0007-NFSD-Update-find_in_sessionid_hashtbl-to-handle-cour.patch and
>> 0008-NFSD-Update-find_client_in_id_table-to-handle-courte.patch to:
>>
>> . set cl_cs_client_stare to NFSD4_CLIENT_ACTIVE when reactive
>> courtesy client
>>
>> v20:
>>
>> . modify 0006-NFSD-Update-find_clp_in_name_tree-to-handle-courtesy.patch to:
>> . add nfsd4_discard_reconnect_clnt
>> . replace call to nfsd4_discard_courtesy_clnt with
>> nfsd4_discard_reconnect_clnt
>>
>> . modify 0007-NFSD-Update-find_in_sessionid_hashtbl-to-handle-cour.patch to:
>> . replace call to nfsd4_discard_courtesy_clnt with
>> nfsd4_discard_reconnect_clnt
>>
>> . modify 0008-NFSD-Update-find_client_in_id_table-to-handle-courte.patch
>> . replace call to nfsd4_discard_courtesy_clnt with
>> nfsd4_discard_reconnect_clnt