From: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Sun, 10 Oct 2021 10:58:12 +0200
Subject: [PATCH] NFSv4: Fixes for nfs4_inode_return_delegation()
Git-commit: 6e176d47160cec8bcaa28d9aa06926d72d54237c
Patch-mainline: v5.16
References: git-fixes

We mustn't call nfs_wb_all() on anything other than a regular file.
Furthermore, we can exit early when we don't hold a delegation.

Reported-by: David Wysochanski <dwysocha@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Acked-by: NeilBrown <neilb@suse.com>

---
 fs/nfs/delegation.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -755,11 +755,13 @@ int nfs4_inode_return_delegation(struct
 	struct nfs_delegation *delegation;
 
 	delegation = nfs_start_delegation_return(nfsi);
-	/* Synchronous recall of any application leases */
-	break_lease(inode, O_WRONLY | O_RDWR);
-	nfs_wb_all(inode);
-	if (delegation != NULL)
+	if (delegation != NULL) {
+		/* Synchronous recall of any application leases */
+		break_lease(inode, O_WRONLY | O_RDWR);
+		if (S_ISREG(inode->i_mode))
+			nfs_wb_all(inode);
 		return nfs_end_delegation_return(inode, delegation, 1);
+	}
 	return 0;
 }