NFSv4: It is not safe to dereference lsp->ls_state in release_lockowner

It is quite possible for the release_lockowner RPC call to race with the
close RPC call, in which case, we cannot dereference lsp->ls_state in
order to find the nfs_server.

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

3 files changed, 7 insertions, 7 deletions

diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index b47bdb9c1612..97ecc863dd76 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -340,7 +340,7 @@ extern void nfs_increment_lock_seqid(int status, struct nfs_seqid *seqid);
 extern void nfs_release_seqid(struct nfs_seqid *seqid);
 extern void nfs_free_seqid(struct nfs_seqid *seqid);
 
-extern void nfs4_free_lock_state(struct nfs4_lock_state *lsp);
+extern void nfs4_free_lock_state(struct nfs_server *server, struct nfs4_lock_state *lsp);
 
 extern const nfs4_stateid zero_stateid;
 
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 5e0961acfef4..d41d97fb4cb9 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -4760,13 +4760,14 @@ out:
 
 struct nfs_release_lockowner_data {
         struct nfs4_lock_state *lsp;
+        struct nfs_server *server;
         struct nfs_release_lockowner_args args;
 };
 
 static void nfs4_release_lockowner_release(void *calldata)
 {
         struct nfs_release_lockowner_data *data = calldata;
-        nfs4_free_lock_state(data->lsp);
+        nfs4_free_lock_state(data->server, data->lsp);
         kfree(calldata);
 }
 
@@ -4788,6 +4789,7 @@ int nfs4_release_lockowner(struct nfs4_lock_state *lsp)
         if (!data)
                 return -ENOMEM;
         data->lsp = lsp;
+        data->server = server;
         data->args.lock_owner.clientid = server->nfs_client->cl_clientid;
         data->args.lock_owner.id = lsp->ls_seqid.owner_id;
         data->args.lock_owner.s_dev = server->s_dev;
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 12b068f2ec91..0f43414eb25a 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -791,10 +791,8 @@ out_free:
         return NULL;
 }
 
-void nfs4_free_lock_state(struct nfs4_lock_state *lsp)
+void nfs4_free_lock_state(struct nfs_server *server, struct nfs4_lock_state *lsp)
 {
-        struct nfs_server *server = lsp->ls_state->owner->so_server;
-
         ida_simple_remove(&server->lockowner_id, lsp->ls_seqid.owner_id);
         nfs4_destroy_seqid_counter(&lsp->ls_seqid);
         kfree(lsp);
@@ -828,7 +826,7 @@ static struct nfs4_lock_state *nfs4_get_lock_state(struct nfs4_state *state, fl_
         }
         spin_unlock(&state->state_lock);
         if (new != NULL)
-                nfs4_free_lock_state(new);
+                nfs4_free_lock_state(state->owner->so_server, new);
         return lsp;
 }
 
@@ -853,7 +851,7 @@ void nfs4_put_lock_state(struct nfs4_lock_state *lsp)
                 if (nfs4_release_lockowner(lsp) == 0)
                         return;
         }
-        nfs4_free_lock_state(lsp);
+        nfs4_free_lock_state(lsp->ls_state->owner->so_server, lsp);
 }
 
 static void nfs4_fl_copy_lock(struct file_lock *dst, struct file_lock *src)