NFSv4: nfs4_copy_delegation_stateid() must fail if the delegation is invalid

We must not allow the use of delegations that have been revoked or are
being returned.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Fixes: 869f9dfa4d6d ("NFSv4: Fix races between nfs_remove_bad_delegation()...")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org # v3.19+
Tested-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 86d2c748140b8a2f5fdfdf48a9c5ed624ccee154..b9c65421ed812c04fad08d18290449634a7d85fb 100644 (file)
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -41,6 +41,17 @@ void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
        set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
 }
 
+static bool
+nfs4_is_valid_delegation(const struct nfs_delegation *delegation,
+               fmode_t flags)
+{
+       if (delegation != NULL && (delegation->type & flags) == flags &&
+           !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
+           !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
+               return true;
+       return false;
+}
+
 static int
 nfs4_do_check_delegation(struct inode *inode, fmode_t flags, bool mark)
 {
@@ -50,9 +61,7 @@ nfs4_do_check_delegation(struct inode *inode, fmode_t flags, bool mark)
        flags &= FMODE_READ|FMODE_WRITE;
        rcu_read_lock();
        delegation = rcu_dereference(NFS_I(inode)->delegation);
-       if (delegation != NULL && (delegation->type & flags) == flags &&
-           !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
-           !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
+       if (nfs4_is_valid_delegation(delegation, flags)) {
                if (mark)
                        nfs_mark_delegation_referenced(delegation);
                ret = 1;
@@ -894,7 +903,7 @@ bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags,
        flags &= FMODE_READ|FMODE_WRITE;
        rcu_read_lock();
        delegation = rcu_dereference(nfsi->delegation);
-       ret = (delegation != NULL && (delegation->type & flags) == flags);
+       ret = nfs4_is_valid_delegation(delegation, flags);
        if (ret) {
                nfs4_stateid_copy(dst, &delegation->stateid);
                nfs_mark_delegation_referenced(delegation);