nfsd: eliminate the NFSD_FILE_BREAK_* flags

We had a report from the spring Bake-a-thon of data corruption in some
nfstest_interop tests. Looking at the traces showed the NFS server
allowing a v3 WRITE to proceed while a read delegation was still
outstanding.

Currently, we only set NFSD_FILE_BREAK_* flags if
NFSD_MAY_NOT_BREAK_LEASE was set when we call nfsd_file_alloc.
NFSD_MAY_NOT_BREAK_LEASE was intended to be set when finding files for
COMMIT ops, where we need a writeable filehandle but don't need to
break read leases.

It doesn't make any sense to consult that flag when allocating a file
since the file may be used on subsequent calls where we do want to break
the lease (and the usage of it here seems to be reverse from what it
should be anyway).

Also, after calling nfsd_open_break_lease, we don't want to clear the
BREAK_* bits. A lease could end up being set on it later (more than
once) and we need to be able to break those leases as well.

This means that the NFSD_FILE_BREAK_* flags now just mirror
NFSD_MAY_{READ,WRITE} flags, so there's no need for them at all. Just
drop those flags and unconditionally call nfsd_open_break_lease every
time.
Reported-by: Olga Kornieskaia <kolga@netapp.com>
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2107360
Fixes: 65294c1f (nfsd: add a new struct file caching facility to nfsd)
Cc: <stable@vger.kernel.org> # 5.4.x : bb283ca1 NFSD: Clean up the show_nf_flags() macro
Cc: <stable@vger.kernel.org> # 5.4.x
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/filecache.c

@@ -184,12 +184,6 @@ nfsd_file_alloc(struct inode *inode, unsigned int may, unsigned int hashval,
 		nf->nf_hashval = hashval;
 		refcount_set(&nf->nf_ref, 1);
 		nf->nf_may = may & NFSD_FILE_MAY_MASK;
-		if (may & NFSD_MAY_NOT_BREAK_LEASE) {
-			if (may & NFSD_MAY_WRITE)
-				__set_bit(NFSD_FILE_BREAK_WRITE, &nf->nf_flags);
-			if (may & NFSD_MAY_READ)
-				__set_bit(NFSD_FILE_BREAK_READ, &nf->nf_flags);
-		}
 		nf->nf_mark = NULL;
 		trace_nfsd_file_alloc(nf);
 	}
@@ -958,21 +952,7 @@ nfsd_do_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
 
 	this_cpu_inc(nfsd_file_cache_hits);
 
-	if (!(may_flags & NFSD_MAY_NOT_BREAK_LEASE)) {
-		bool write = (may_flags & NFSD_MAY_WRITE);
-
-		if (test_bit(NFSD_FILE_BREAK_READ, &nf->nf_flags) ||
-		    (test_bit(NFSD_FILE_BREAK_WRITE, &nf->nf_flags) && write)) {
-			status = nfserrno(nfsd_open_break_lease(
-					file_inode(nf->nf_file), may_flags));
-			if (status == nfs_ok) {
-				clear_bit(NFSD_FILE_BREAK_READ, &nf->nf_flags);
-				if (write)
-					clear_bit(NFSD_FILE_BREAK_WRITE,
-						  &nf->nf_flags);
-			}
-		}
-	}
+	status = nfserrno(nfsd_open_break_lease(file_inode(nf->nf_file), may_flags));
 out:
 	if (status == nfs_ok) {
 		*pnf = nf;

fs/nfsd/filecache.h

@@ -37,9 +37,7 @@ struct nfsd_file {
 	struct net		*nf_net;
 #define NFSD_FILE_HASHED	(0)
 #define NFSD_FILE_PENDING	(1)
-#define NFSD_FILE_BREAK_READ	(2)
-#define NFSD_FILE_BREAK_WRITE	(3)
-#define NFSD_FILE_REFERENCED	(4)
+#define NFSD_FILE_REFERENCED	(2)
 	unsigned long		nf_flags;
 	struct inode		*nf_inode;
 	unsigned int		nf_hashval;

fs/nfsd/trace.h

@@ -696,8 +696,6 @@ DEFINE_CLID_EVENT(confirmed_r);
 	__print_flags(val, "|",						\
 		{ 1 << NFSD_FILE_HASHED,	"HASHED" },		\
 		{ 1 << NFSD_FILE_PENDING,	"PENDING" },		\
-		{ 1 << NFSD_FILE_BREAK_READ,	"BREAK_READ" },		\
-		{ 1 << NFSD_FILE_BREAK_WRITE,	"BREAK_WRITE" },	\
 		{ 1 << NFSD_FILE_REFERENCED,	"REFERENCED"})
 
 DECLARE_EVENT_CLASS(nfsd_file_class,