Passes pynfs, fstests, and the git regression suite. Please apply
these to origin/linux-5.10.y.
---
Chuck Lever (2):
NFSD: Modernize nfsd4_release_lockowner()
NFSD: Add documenting comment for nfsd4_release_lockowner()
NeilBrown (1):
nfsd: fix RELEASE_LOCKOWNER
fs/nfsd/nfs4state.c | 65 +++++++++++++++++++++++++--------------------
1 file changed, 36 insertions(+), 29 deletions(-)
--
Chuck Lever
From: NeilBrown <[email protected]>
[ Upstream commit edcf9725150e42beeca42d085149f4c88fa97afd ]
The test on so_count in nfsd4_release_lockowner() is nonsense and
harmful. Revert to using check_for_locks(), changing that to not sleep.
First: harmful.
As is documented in the kdoc comment for nfsd4_release_lockowner(), the
test on so_count can transiently return a false positive resulting in a
return of NFS4ERR_LOCKS_HELD when in fact no locks are held. This is
clearly a protocol violation and with the Linux NFS client it can cause
incorrect behaviour.
If RELEASE_LOCKOWNER is sent while some other thread is still
processing a LOCK request which failed because, at the time that request
was received, the given owner held a conflicting lock, then the nfsd
thread processing that LOCK request can hold a reference (conflock) to
the lock owner that causes nfsd4_release_lockowner() to return an
incorrect error.
The Linux NFS client ignores that NFS4ERR_LOCKS_HELD error because it
never sends NFS4_RELEASE_LOCKOWNER without first releasing any locks, so
it knows that the error is impossible. It assumes the lock owner was in
fact released so it feels free to use the same lock owner identifier in
some later locking request.
When it does reuse a lock owner identifier for which a previous RELEASE
failed, it will naturally use a lock_seqid of zero. However the server,
which didn't release the lock owner, will expect a larger lock_seqid and
so will respond with NFS4ERR_BAD_SEQID.
So clearly it is harmful to allow a false positive, which testing
so_count allows.
The test is nonsense because ... well... it doesn't mean anything.
so_count is the sum of three different counts.
1/ the set of states listed on so_stateids
2/ the set of active vfs locks owned by any of those states
3/ various transient counts such as for conflicting locks.
When it is tested against '2' it is clear that one of these is the
transient reference obtained by find_lockowner_str_locked(). It is not
clear what the other one is expected to be.
In practice, the count is often 2 because there is precisely one state
on so_stateids. If there were more, this would fail.
In my testing I see two circumstances when RELEASE_LOCKOWNER is called.
In one case, CLOSE is called before RELEASE_LOCKOWNER. That results in
all the lock states being removed, and so the lockowner being discarded
(it is removed when there are no more references which usually happens
when the lock state is discarded). When nfsd4_release_lockowner() finds
that the lock owner doesn't exist, it returns success.
The other case shows an so_count of '2' and precisely one state listed
in so_stateid. It appears that the Linux client uses a separate lock
owner for each file resulting in one lock state per lock owner, so this
test on '2' is safe. For another client it might not be safe.
So this patch changes check_for_locks() to use the (newish)
find_any_file_locked() so that it doesn't take a reference on the
nfs4_file and so never calls nfsd_file_put(), and so never sleeps. With
this check is it safe to restore the use of check_for_locks() rather
than testing so_count against the mysterious '2'.
Fixes: ce3c4ad7f4ce ("NFSD: Fix possible sleep during nfsd4_release_lockowner()")
Signed-off-by: NeilBrown <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
Cc: [email protected] # v6.2+
Signed-off-by: Chuck Lever <[email protected]>
---
fs/nfsd/nfs4state.c | 26 +++++++++++++++-----------
1 file changed, 15 insertions(+), 11 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index b6480be7b5e6..16b073c63798 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -7080,14 +7080,16 @@ check_for_locks(struct nfs4_file *fp, struct nfs4_lockowner *lowner)
{
struct file_lock *fl;
int status = false;
- struct nfsd_file *nf = find_any_file(fp);
+ struct nfsd_file *nf;
struct inode *inode;
struct file_lock_context *flctx;
+ spin_lock(&fp->fi_lock);
+ nf = find_any_file_locked(fp);
if (!nf) {
/* Any valid lock stateid should have some sort of access */
WARN_ON_ONCE(1);
- return status;
+ goto out;
}
inode = locks_inode(nf->nf_file);
@@ -7103,7 +7105,8 @@ check_for_locks(struct nfs4_file *fp, struct nfs4_lockowner *lowner)
}
spin_unlock(&flctx->flc_lock);
}
- nfsd_file_put(nf);
+out:
+ spin_unlock(&fp->fi_lock);
return status;
}
@@ -7113,10 +7116,8 @@ check_for_locks(struct nfs4_file *fp, struct nfs4_lockowner *lowner)
* @cstate: NFSv4 COMPOUND state
* @u: RELEASE_LOCKOWNER arguments
*
- * The lockowner's so_count is bumped when a lock record is added
- * or when copying a conflicting lock. The latter case is brief,
- * but can lead to fleeting false positives when looking for
- * locks-in-use.
+ * Check if theree are any locks still held and if not - free the lockowner
+ * and any lock state that is owned.
*
* Return values:
* %nfs_ok: lockowner released or not found
@@ -7152,10 +7153,13 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp,
spin_unlock(&clp->cl_lock);
return nfs_ok;
}
- if (atomic_read(&lo->lo_owner.so_count) != 2) {
- spin_unlock(&clp->cl_lock);
- nfs4_put_stateowner(&lo->lo_owner);
- return nfserr_locks_held;
+
+ list_for_each_entry(stp, &lo->lo_owner.so_stateids, st_perstateowner) {
+ if (check_for_locks(stp->st_stid.sc_file, lo)) {
+ spin_unlock(&clp->cl_lock);
+ nfs4_put_stateowner(&lo->lo_owner);
+ return nfserr_locks_held;
+ }
}
unhash_lockowner_locked(lo);
while (!list_empty(&lo->lo_owner.so_stateids)) {
From: Chuck Lever <[email protected]>
[ Upstream commit bd8fdb6e545f950f4654a9a10d7e819ad48146e5 ]
Refactor: Use existing helpers that other lock operations use. This
change removes several automatic variables, so re-organize the
variable declarations for readability.
Stable-dep-of: edcf9725150e ("nfsd: fix RELEASE_LOCKOWNER")
Signed-off-by: Chuck Lever <[email protected]>
---
fs/nfsd/nfs4state.c | 36 +++++++++++-------------------------
1 file changed, 11 insertions(+), 25 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index d402ca0b535f..1b40b2197ce6 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -7113,16 +7113,13 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp,
union nfsd4_op_u *u)
{
struct nfsd4_release_lockowner *rlockowner = &u->release_lockowner;
+ struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
clientid_t *clid = &rlockowner->rl_clientid;
- struct nfs4_stateowner *sop;
- struct nfs4_lockowner *lo = NULL;
struct nfs4_ol_stateid *stp;
- struct xdr_netobj *owner = &rlockowner->rl_owner;
- unsigned int hashval = ownerstr_hashval(owner);
- __be32 status;
- struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
+ struct nfs4_lockowner *lo;
struct nfs4_client *clp;
- LIST_HEAD (reaplist);
+ LIST_HEAD(reaplist);
+ __be32 status;
dprintk("nfsd4_release_lockowner clientid: (%08x/%08x):\n",
clid->cl_boot, clid->cl_id);
@@ -7130,30 +7127,19 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp,
status = lookup_clientid(clid, cstate, nn, false);
if (status)
return status;
-
clp = cstate->clp;
- /* Find the matching lock stateowner */
- spin_lock(&clp->cl_lock);
- list_for_each_entry(sop, &clp->cl_ownerstr_hashtbl[hashval],
- so_strhash) {
- if (sop->so_is_open_owner || !same_owner_str(sop, owner))
- continue;
-
- if (atomic_read(&sop->so_count) != 1) {
- spin_unlock(&clp->cl_lock);
- return nfserr_locks_held;
- }
-
- lo = lockowner(sop);
- nfs4_get_stateowner(sop);
- break;
- }
+ spin_lock(&clp->cl_lock);
+ lo = find_lockowner_str_locked(clp, &rlockowner->rl_owner);
if (!lo) {
spin_unlock(&clp->cl_lock);
return status;
}
-
+ if (atomic_read(&lo->lo_owner.so_count) != 2) {
+ spin_unlock(&clp->cl_lock);
+ nfs4_put_stateowner(&lo->lo_owner);
+ return nfserr_locks_held;
+ }
unhash_lockowner_locked(lo);
while (!list_empty(&lo->lo_owner.so_stateids)) {
stp = list_first_entry(&lo->lo_owner.so_stateids,
From: Chuck Lever <[email protected]>
[ Upstream commit 043862b09cc00273e35e6c3a6389957953a34207 ]
And return explicit nfserr values that match what is documented in the
new comment / API contract.
Stable-dep-of: edcf9725150e ("nfsd: fix RELEASE_LOCKOWNER")
Signed-off-by: Chuck Lever <[email protected]>
---
fs/nfsd/nfs4state.c | 23 ++++++++++++++++++++---
1 file changed, 20 insertions(+), 3 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 1b40b2197ce6..b6480be7b5e6 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -7107,6 +7107,23 @@ check_for_locks(struct nfs4_file *fp, struct nfs4_lockowner *lowner)
return status;
}
+/**
+ * nfsd4_release_lockowner - process NFSv4.0 RELEASE_LOCKOWNER operations
+ * @rqstp: RPC transaction
+ * @cstate: NFSv4 COMPOUND state
+ * @u: RELEASE_LOCKOWNER arguments
+ *
+ * The lockowner's so_count is bumped when a lock record is added
+ * or when copying a conflicting lock. The latter case is brief,
+ * but can lead to fleeting false positives when looking for
+ * locks-in-use.
+ *
+ * Return values:
+ * %nfs_ok: lockowner released or not found
+ * %nfserr_locks_held: lockowner still in use
+ * %nfserr_stale_clientid: clientid no longer active
+ * %nfserr_expired: clientid not recognized
+ */
__be32
nfsd4_release_lockowner(struct svc_rqst *rqstp,
struct nfsd4_compound_state *cstate,
@@ -7133,7 +7150,7 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp,
lo = find_lockowner_str_locked(clp, &rlockowner->rl_owner);
if (!lo) {
spin_unlock(&clp->cl_lock);
- return status;
+ return nfs_ok;
}
if (atomic_read(&lo->lo_owner.so_count) != 2) {
spin_unlock(&clp->cl_lock);
@@ -7149,11 +7166,11 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp,
put_ol_stateid_locked(stp, &reaplist);
}
spin_unlock(&clp->cl_lock);
+
free_ol_stateid_reaplist(&reaplist);
remove_blocked_locks(lo);
nfs4_put_stateowner(&lo->lo_owner);
-
- return status;
+ return nfs_ok;
}
static inline struct nfs4_client_reclaim *