From a9b8d90f87263f985fa14250fc8caf7bfcde8803 Mon Sep 17 00:00:00 2001 From: Benjamin Coddington Date: Thu, 24 Aug 2023 14:52:19 -0400 Subject: [PATCH] NFSv4: fairly test all delegations on a SEQ4_ revocation When the client is required to use TEST_STATEID to discover which delegation(s) have been revoked, it may continually test delegations at the head of the list if the server continues to be unsatisfied and send SEQ4_STATUS_RECALLABLE_STATE_REVOKED. For a large number of delegations this behavior is prone to live-lock because the client may never be able to test and free revoked state at the end of the list since the SEQ4_STATUS_RECALLABLE_STATE_REVOKED will cause us to flag delegations at the head of the list to be tested. This problem is further exacerbated by the state manager's willingness to be scheduled out on a busy system while testing the list of delegations. Keep a generation counter for each attempt to test all delegations, and skip delegations that have already been tested in the current pass. Signed-off-by: Benjamin Coddington Tested-by: Torkil Svensgaard Tested-by: Ruben Vestergaard Signed-off-by: Trond Myklebust --- fs/nfs/delegation.c | 7 ++++++- fs/nfs/delegation.h | 1 + include/linux/nfs_fs_sb.h | 1 + 3 files changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c index cf7365581031..fa1a14def45c 100644 --- a/fs/nfs/delegation.c +++ b/fs/nfs/delegation.c @@ -448,6 +448,7 @@ int nfs_inode_set_delegation(struct inode *inode, const struct cred *cred, delegation->cred = get_cred(cred); delegation->inode = inode; delegation->flags = 1<test_gen = 0; spin_lock_init(&delegation->lock); spin_lock(&clp->cl_lock); @@ -1294,6 +1295,8 @@ static int nfs_server_reap_expired_delegations(struct nfs_server *server, struct inode *inode; const struct cred *cred; nfs4_stateid stateid; + unsigned long gen = ++server->delegation_gen; + restart: rcu_read_lock(); restart_locked: @@ -1303,7 +1306,8 @@ restart_locked: test_bit(NFS_DELEGATION_RETURNING, &delegation->flags) || test_bit(NFS_DELEGATION_TEST_EXPIRED, - &delegation->flags) == 0) + &delegation->flags) == 0 || + delegation->test_gen == gen) continue; inode = nfs_delegation_grab_inode(delegation); if (inode == NULL) @@ -1312,6 +1316,7 @@ restart_locked: cred = get_cred_rcu(delegation->cred); nfs4_stateid_copy(&stateid, &delegation->stateid); spin_unlock(&delegation->lock); + delegation->test_gen = gen; clear_bit(NFS_DELEGATION_TEST_EXPIRED, &delegation->flags); rcu_read_unlock(); nfs_delegation_test_free_expired(inode, &stateid, cred); diff --git a/fs/nfs/delegation.h b/fs/nfs/delegation.h index 1c378992b7c0..a6f495d012cf 100644 --- a/fs/nfs/delegation.h +++ b/fs/nfs/delegation.h @@ -21,6 +21,7 @@ struct nfs_delegation { fmode_t type; unsigned long pagemod_limit; __u64 change_attr; + unsigned long test_gen; unsigned long flags; refcount_t refcount; spinlock_t lock; diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h index cd628c4b011e..cd797e00fe35 100644 --- a/include/linux/nfs_fs_sb.h +++ b/include/linux/nfs_fs_sb.h @@ -239,6 +239,7 @@ struct nfs_server { struct list_head delegations; struct list_head ss_copies; + unsigned long delegation_gen; unsigned long mig_gen; unsigned long mig_status; #define NFS_MIG_IN_TRANSITION (1)