NFS: Fix a soft lockup in the delegation recovery code

[ Upstream commit 6f9449be53f3ce383caed797708b332ede8d952c ]

Fix a soft lockup when NFS client delegation recovery is attempted
but the inode is in the process of being freed. When the
igrab(inode) call fails, and we have to restart the recovery process,
we need to ensure that we won't attempt to recover the same delegation
again.

Fixes: 45870d6909d5a ("NFSv4.1: Test delegation stateids when server...")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 74ff459..b0c0c2f 100644 (file)
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -240,6 +240,8 @@ static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation
        spin_lock(&delegation->lock);
        if (delegation->inode != NULL)
                inode = igrab(delegation->inode);
+       if (!inode)
+               set_bit(NFS_DELEGATION_INODE_FREEING, &delegation->flags);
        spin_unlock(&delegation->lock);
        return inode;
 }
@@ -955,10 +957,11 @@ restart:
        list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
                list_for_each_entry_rcu(delegation, &server->delegations,
                                                                super_list) {
-                       if (test_bit(NFS_DELEGATION_RETURNING,
-                                               &delegation->flags))
-                               continue;
-                       if (test_bit(NFS_DELEGATION_NEED_RECLAIM,
+                       if (test_bit(NFS_DELEGATION_INODE_FREEING,
+                                               &delegation->flags) ||
+                           test_bit(NFS_DELEGATION_RETURNING,
+                                               &delegation->flags) ||
+                           test_bit(NFS_DELEGATION_NEED_RECLAIM,
                                                &delegation->flags) == 0)
                                continue;
                        if (!nfs_sb_active(server->super))
@@ -1064,10 +1067,11 @@ restart:
        list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
                list_for_each_entry_rcu(delegation, &server->delegations,
                                                                super_list) {
-                       if (test_bit(NFS_DELEGATION_RETURNING,
-                                               &delegation->flags))
-                               continue;
-                       if (test_bit(NFS_DELEGATION_TEST_EXPIRED,
+                       if (test_bit(NFS_DELEGATION_INODE_FREEING,
+                                               &delegation->flags) ||
+                           test_bit(NFS_DELEGATION_RETURNING,
+                                               &delegation->flags) ||
+                           test_bit(NFS_DELEGATION_TEST_EXPIRED,
                                                &delegation->flags) == 0)
                                continue;
                        if (!nfs_sb_active(server->super))

diff --git a/fs/nfs/delegation.h b/fs/nfs/delegation.h
index dd0f3ee..f09b153 100644 (file)
--- a/fs/nfs/delegation.h
+++ b/fs/nfs/delegation.h
@@ -34,6 +34,7 @@ enum {
        NFS_DELEGATION_RETURNING,
        NFS_DELEGATION_REVOKED,
        NFS_DELEGATION_TEST_EXPIRED,
+       NFS_DELEGATION_INODE_FREEING,
 };
 
 int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred,