NFSD: Define a proc_layoutcommit for the FlexFiles layout type

Avoid a crash if a pNFS client should happen to send a LAYOUTCOMMIT
operation on a FlexFiles layout.

Reported-by: Robert Morris <[email protected]>
Closes: https://lore.kernel.org/linux-nfs/[email protected]/T/#t
Cc: Thomas Haynes <[email protected]>
Cc: [email protected]
Fixes: 9b9960a ("nfsd: Add a super simple flex file server")
Signed-off-by: Chuck Lever <[email protected]>

Author: chucklever

fs/nfsd/flexfilelayout.c

@@ -125,6 +125,13 @@ nfsd4_ff_proc_getdeviceinfo(struct super_block *sb, struct svc_rqst *rqstp,
 	return 0;
 }
 
+static __be32
+nfsd4_ff_proc_layoutcommit(struct inode *inode, struct svc_rqst *rqstp,
+		struct nfsd4_layoutcommit *lcp)
+{
+	return nfs_ok;
+}
+
 const struct nfsd4_layout_ops ff_layout_ops = {
 	.notify_types		=
 			NOTIFY_DEVICEID4_DELETE | NOTIFY_DEVICEID4_CHANGE,
@@ -133,4 +140,5 @@ const struct nfsd4_layout_ops ff_layout_ops = {
 	.encode_getdeviceinfo	= nfsd4_ff_encode_getdeviceinfo,
 	.proc_layoutget		= nfsd4_ff_proc_layoutget,
 	.encode_layoutget	= nfsd4_ff_encode_layoutget,
+	.proc_layoutcommit	= nfsd4_ff_proc_layoutcommit,
 };