[PATCH 1/3] NFSv4: Fix a potential state reclaim deadlock

[PATCH 1/3] NFSv4: Fix a potential state reclaim deadlock

[trondmy]

From: Trond Myklebust <trond.myklebust@hammerspace.com>

If the server reboots while we are engaged in a delegation return, and
there is a pNFS layout with return-on-close set, then the current code
can end up deadlocking in pnfs_roc() when nfs_inode_set_delegation()
tries to return the old delegation.
Now that delegreturn actually uses its own copy of the stateid, it
should be safe to just always update the delegation stateid in place.

Fixes: 078000d02d57 ("pNFS: We want return-on-close to complete when evicting the inode")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/delegation.c | 36 +++++++++++++++++-------------------
 1 file changed, 17 insertions(+), 19 deletions(-)

diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 5c97cad741a7..ead8a0e06abf 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -228,8 +228,7 @@ static int nfs_delegation_claim_opens(struct inode *inode,
  *
  */
 void nfs_inode_reclaim_delegation(struct inode *inode, const struct cred *cred,
-				  fmode_t type,
-				  const nfs4_stateid *stateid,
+				  fmode_t type, const nfs4_stateid *stateid,
 				  unsigned long pagemod_limit)
 {
 	struct nfs_delegation *delegation;
@@ -239,25 +238,24 @@ void nfs_inode_reclaim_delegation(struct inode *inode, const struct cred *cred,
 	delegation = rcu_dereference(NFS_I(inode)->delegation);
 	if (delegation != NULL) {
 		spin_lock(&delegation->lock);
-		if (nfs4_is_valid_delegation(delegation, 0)) {
-			nfs4_stateid_copy(&delegation->stateid, stateid);
-			delegation->type = type;
-			delegation->pagemod_limit = pagemod_limit;
-			oldcred = delegation->cred;
-			delegation->cred = get_cred(cred);
-			clear_bit(NFS_DELEGATION_NEED_RECLAIM,
-				  &delegation->flags);
-			spin_unlock(&delegation->lock);
-			rcu_read_unlock();
-			put_cred(oldcred);
-			trace_nfs4_reclaim_delegation(inode, type);
-			return;
-		}
-		/* We appear to have raced with a delegation return. */
+		nfs4_stateid_copy(&delegation->stateid, stateid);
+		delegation->type = type;
+		delegation->pagemod_limit = pagemod_limit;
+		oldcred = delegation->cred;
+		delegation->cred = get_cred(cred);
+		clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
+		if (test_and_clear_bit(NFS_DELEGATION_REVOKED,
+				       &delegation->flags))
+			atomic_long_inc(&nfs_active_delegations);
 		spin_unlock(&delegation->lock);
+		rcu_read_unlock();
+		put_cred(oldcred);
+		trace_nfs4_reclaim_delegation(inode, type);
+	} else {
+		rcu_read_unlock();
+		nfs_inode_set_delegation(inode, cred, type, stateid,
+					 pagemod_limit);
 	}
-	rcu_read_unlock();
-	nfs_inode_set_delegation(inode, cred, type, stateid, pagemod_limit);
 }
 
 static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
-- 
2.37.3

[PATCH 2/3] NFSv4.1: Handle RECLAIM_COMPLETE trunking errors

[trondmy]

From: Trond Myklebust <trond.myklebust@hammerspace.com>

If RECLAIM_COMPLETE sets the NFS4CLNT_BIND_CONN_TO_SESSION flag, then we
need to loop back in order to handle it.

Fixes: 0048fdd06614 ("NFSv4.1: RECLAIM_COMPLETE must handle NFS4ERR_CONN_NOT_BOUND_TO_SESSION")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/nfs4state.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 9bab3e9c702a..0b6bd6336c98 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -2671,6 +2671,7 @@ static void nfs4_state_manager(struct nfs_client *clp)
 			if (status < 0)
 				goto out_error;
 			nfs4_state_end_reclaim_reboot(clp);
+			continue;
 		}
 
 		/* Detect expired delegations... */
-- 
2.37.3

[PATCH 3/3] NFSv4.1: We must always send RECLAIM_COMPLETE after a reboot

[trondmy]

From: Trond Myklebust <trond.myklebust@hammerspace.com>

Currently, we are only guaranteed to send RECLAIM_COMPLETE if we have
open state to recover. Fix the client to always send RECLAIM_COMPLETE
after setting up the lease.

Fixes: fce5c838e133 ("nfs41: RECLAIM_COMPLETE functionality")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/nfs4state.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 0b6bd6336c98..a629d7db9420 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1787,6 +1787,7 @@ static void nfs4_state_mark_reclaim_helper(struct nfs_client *clp,
 
 static void nfs4_state_start_reclaim_reboot(struct nfs_client *clp)
 {
+	set_bit(NFS4CLNT_RECLAIM_REBOOT, &clp->cl_state);
 	/* Mark all delegations for reclaim */
 	nfs_delegation_mark_reclaim(clp);
 	nfs4_state_mark_reclaim_helper(clp, nfs4_state_mark_reclaim_reboot);
-- 
2.37.3