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NFSv4: Fix up another delegation related race

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When we can update_open_stateid(), we need to be certain that we don't
race with a delegation return. While we could do this by grabbing the
nfs_client->cl_lock, a dedicated spin lock in the delegation structure
will scale better.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust
2008-12-23 15:21:38 -05:00
parent 0cb2659b81
commit 343104308a
3 changed files with 60 additions and 28 deletions
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7
fs/nfs/delegation.c
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@@ -140,13 +140,17 @@ static struct nfs_delegation *nfs_detach_delegation_locked(struct nfs_inode *nfs
if (delegation == NULL)
goto nomatch;
spin_lock(&delegation->lock);
if (stateid != NULL && memcmp(delegation->stateid.data, stateid->data,
sizeof(delegation->stateid.data)) != 0)
goto nomatch;
goto nomatch_unlock;
list_del_rcu(&delegation->super_list);
nfsi->delegation_state = 0;
rcu_assign_pointer(nfsi->delegation, NULL);
spin_unlock(&delegation->lock);
return delegation;
nomatch_unlock:
spin_unlock(&delegation->lock);
nomatch:
return NULL;
}
@@ -172,6 +176,7 @@ int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct
delegation->change_attr = nfsi->change_attr;
delegation->cred = get_rpccred(cred);
delegation->inode = inode;
spin_lock_init(&delegation->lock);
spin_lock(&clp->cl_lock);
if (rcu_dereference(nfsi->delegation) != NULL) {