NFS client fixes for Linux 6.2

Highlights include:
 
 Bugfixes
 - Fix a race in the RPCSEC_GSS upcall code that causes hung RPC calls
 - Fix a broken coalescing test in the pNFS file layout driver
 - Ensure that the access cache rcu path also applies the login test
 - Fix up for a sparse warning
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Merge tag 'nfs-for-6.2-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client fixes from Trond Myklebust:

 - Fix a race in the RPCSEC_GSS upcall code that causes hung RPC calls

 - Fix a broken coalescing test in the pNFS file layout driver

 - Ensure that the access cache rcu path also applies the login test

 - Fix up for a sparse warning

* tag 'nfs-for-6.2-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  NFS: Fix up a sparse warning
  NFS: Judge the file access cache's timestamp in rcu path
  pNFS/filelayout: Fix coalescing test for single DS
  SUNRPC: ensure the matching upcall is in-flight upon downcall

fs/nfs/dir.c

@@ -2957,12 +2957,14 @@ static u64 nfs_access_login_time(const struct task_struct *task,
 				 const struct cred *cred)
 {
 	const struct task_struct *parent;
+	const struct cred *pcred;
 	u64 ret;
 
 	rcu_read_lock();
 	for (;;) {
 		parent = rcu_dereference(task->real_parent);
-		if (parent == task || cred_fscmp(parent->cred, cred) != 0)
+		pcred = rcu_dereference(parent->cred);
+		if (parent == task || cred_fscmp(pcred, cred) != 0)
 			break;
 		task = parent;
 	}
@@ -3023,6 +3025,7 @@ static int nfs_access_get_cached_rcu(struct inode *inode, const struct cred *cre
 	 * but do it without locking.
 	 */
 	struct nfs_inode *nfsi = NFS_I(inode);
+	u64 login_time = nfs_access_login_time(current, cred);
 	struct nfs_access_entry *cache;
 	int err = -ECHILD;
 	struct list_head *lh;
@@ -3037,6 +3040,8 @@ static int nfs_access_get_cached_rcu(struct inode *inode, const struct cred *cre
 		cache = NULL;
 	if (cache == NULL)
 		goto out;
+	if ((s64)(login_time - cache->timestamp) > 0)
+		goto out;
 	if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_ACCESS))
 		goto out;
 	*mask = cache->mask;

fs/nfs/filelayout/filelayout.c

@@ -783,6 +783,12 @@ filelayout_alloc_lseg(struct pnfs_layout_hdr *layoutid,
 	return &fl->generic_hdr;
 }
 
+static bool
+filelayout_lseg_is_striped(const struct nfs4_filelayout_segment *flseg)
+{
+	return flseg->num_fh > 1;
+}
+
 /*
  * filelayout_pg_test(). Called by nfs_can_coalesce_requests()
  *
@@ -803,6 +809,8 @@ filelayout_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
 	size = pnfs_generic_pg_test(pgio, prev, req);
 	if (!size)
 		return 0;
+	else if (!filelayout_lseg_is_striped(FILELAYOUT_LSEG(pgio->pg_lseg)))
+		return size;
 
 	/* see if req and prev are in the same stripe */
 	if (prev) {

include/linux/sunrpc/rpc_pipe_fs.h

@@ -92,6 +92,11 @@ extern ssize_t rpc_pipe_generic_upcall(struct file *, struct rpc_pipe_msg *,
 				       char __user *, size_t);
 extern int rpc_queue_upcall(struct rpc_pipe *, struct rpc_pipe_msg *);
 
+/* returns true if the msg is in-flight, i.e., already eaten by the peer */
+static inline bool rpc_msg_is_inflight(const struct rpc_pipe_msg *msg) {
+	return (msg->copied != 0 && list_empty(&msg->list));
+}
+
 struct rpc_clnt;
 extern struct dentry *rpc_create_client_dir(struct dentry *, const char *, struct rpc_clnt *);
 extern int rpc_remove_client_dir(struct rpc_clnt *);

net/sunrpc/auth_gss/auth_gss.c

@@ -302,7 +302,7 @@ __gss_find_upcall(struct rpc_pipe *pipe, kuid_t uid, const struct gss_auth *auth
 	list_for_each_entry(pos, &pipe->in_downcall, list) {
 		if (!uid_eq(pos->uid, uid))
 			continue;
-		if (auth && pos->auth->service != auth->service)
+		if (pos->auth->service != auth->service)
 			continue;
 		refcount_inc(&pos->count);
 		return pos;
@@ -686,6 +686,21 @@ gss_create_upcall(struct gss_auth *gss_auth, struct gss_cred *gss_cred)
 	return err;
 }
 
+static struct gss_upcall_msg *
+gss_find_downcall(struct rpc_pipe *pipe, kuid_t uid)
+{
+	struct gss_upcall_msg *pos;
+	list_for_each_entry(pos, &pipe->in_downcall, list) {
+		if (!uid_eq(pos->uid, uid))
+			continue;
+		if (!rpc_msg_is_inflight(&pos->msg))
+			continue;
+		refcount_inc(&pos->count);
+		return pos;
+	}
+	return NULL;
+}
+
 #define MSG_BUF_MAXSIZE 1024
 
 static ssize_t
@@ -732,7 +747,7 @@ gss_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
 	err = -ENOENT;
 	/* Find a matching upcall */
 	spin_lock(&pipe->lock);
-	gss_msg = __gss_find_upcall(pipe, uid, NULL);
+	gss_msg = gss_find_downcall(pipe, uid);
 	if (gss_msg == NULL) {
 		spin_unlock(&pipe->lock);
 		goto err_put_ctx;