NFSv4: Deal more correctly with duplicate delegations

If a (broken?) server hands out two different delegations for the same
file, then we should return one of them.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 51 insertions, 38 deletions

diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 2dead8d1dd55..b9eadd18ba70 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -125,6 +125,32 @@ void nfs_inode_reclaim_delegation(struct inode *inode, struct rpc_cred *cred, st
         put_rpccred(oldcred);
 }
 
+static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
+{
+        int res = 0;
+
+        res = nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid, issync);
+        nfs_free_delegation(delegation);
+        return res;
+}
+
+static struct nfs_delegation *nfs_detach_delegation_locked(struct nfs_inode *nfsi, const nfs4_stateid *stateid)
+{
+        struct nfs_delegation *delegation = rcu_dereference(nfsi->delegation);
+
+        if (delegation == NULL)
+                goto nomatch;
+        if (stateid != NULL && memcmp(delegation->stateid.data, stateid->data,
+                                sizeof(delegation->stateid.data)) != 0)
+                goto nomatch;
+        list_del_rcu(&delegation->super_list);
+        nfsi->delegation_state = 0;
+        rcu_assign_pointer(nfsi->delegation, NULL);
+        return delegation;
+nomatch:
+        return NULL;
+}
+
 /*
  * Set up a delegation on an inode
  */
@@ -133,6 +159,7 @@ int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct
         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
         struct nfs_inode *nfsi = NFS_I(inode);
         struct nfs_delegation *delegation;
+        struct nfs_delegation *freeme = NULL;
         int status = 0;
 
         delegation = kmalloc(sizeof(*delegation), GFP_KERNEL);
@@ -147,42 +174,45 @@ int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct
         delegation->inode = inode;
 
         spin_lock(&clp->cl_lock);
-        if (rcu_dereference(nfsi->delegation) == NULL) {
-                list_add_rcu(&delegation->super_list, &clp->cl_delegations);
-                nfsi->delegation_state = delegation->type;
-                rcu_assign_pointer(nfsi->delegation, delegation);
-                delegation = NULL;
-        } else {
+        if (rcu_dereference(nfsi->delegation) != NULL) {
                 if (memcmp(&delegation->stateid, &nfsi->delegation->stateid,
-                                        sizeof(delegation->stateid)) != 0 ||
-                                delegation->type != nfsi->delegation->type) {
-                        printk(KERN_WARNING "%s: server %s handed out "
-                                        "a duplicate delegation!\n",
-                                        __FUNCTION__, clp->cl_hostname);
-                        status = -EIO;
+                                        sizeof(delegation->stateid)) == 0 &&
+                                delegation->type == nfsi->delegation->type) {
+                        goto out;
+                }
+                /*
+                 * Deal with broken servers that hand out two
+                 * delegations for the same file.
+                 */
+                dfprintk(FILE, "%s: server %s handed out "
+                                "a duplicate delegation!\n",
+                                __FUNCTION__, clp->cl_hostname);
+                if (delegation->type <= nfsi->delegation->type) {
+                        freeme = delegation;
+                        delegation = NULL;
+                        goto out;
                 }
+                freeme = nfs_detach_delegation_locked(nfsi, NULL);
         }
+        list_add_rcu(&delegation->super_list, &clp->cl_delegations);
+        nfsi->delegation_state = delegation->type;
+        rcu_assign_pointer(nfsi->delegation, delegation);
+        delegation = NULL;
 
         /* Ensure we revalidate the attributes and page cache! */
         spin_lock(&inode->i_lock);
         nfsi->cache_validity |= NFS_INO_REVAL_FORCED;
         spin_unlock(&inode->i_lock);
 
+out:
         spin_unlock(&clp->cl_lock);
         if (delegation != NULL)
                 nfs_free_delegation(delegation);
+        if (freeme != NULL)
+                nfs_do_return_delegation(inode, freeme, 0);
         return status;
 }
 
-static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
-{
-        int res = 0;
-
-        res = nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid, issync);
-        nfs_free_delegation(delegation);
-        return res;
-}
-
 /* Sync all data to disk upon delegation return */
 static void nfs_msync_inode(struct inode *inode)
 {
@@ -211,23 +241,6 @@ static int __nfs_inode_return_delegation(struct inode *inode, struct nfs_delegat
         return nfs_do_return_delegation(inode, delegation, 1);
 }
 
-static struct nfs_delegation *nfs_detach_delegation_locked(struct nfs_inode *nfsi, const nfs4_stateid *stateid)
-{
-        struct nfs_delegation *delegation = rcu_dereference(nfsi->delegation);
-
-        if (delegation == NULL)
-                goto nomatch;
-        if (stateid != NULL && memcmp(delegation->stateid.data, stateid->data,
-                                sizeof(delegation->stateid.data)) != 0)
-                goto nomatch;
-        list_del_rcu(&delegation->super_list);
-        nfsi->delegation_state = 0;
-        rcu_assign_pointer(nfsi->delegation, NULL);
-        return delegation;
-nomatch:
-        return NULL;
-}
-
 /*
  * This function returns the delegation without reclaiming opens
  * or protecting against delegation reclaims.