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 74ff459b75efa2095d0a03c38fdf02e2b7d34d3c..b0c0c2fc2fbac8e353432225e032ff9fa4b65681 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 dd0f3eed3890de367afa06b47b1a2cee1ed17c18..f09b153ac82ff65dcb5b3a7a9671942f07d9926f 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,