[PATCH v3][next] NFSD: Avoid multiple -Wflex-array-member-not-at-end warnings

["Gustavo A. R. Silva" <gustavoars@kernel.org>]

Replace flexible-array member with a fixed-size array.

With this changes, fix many instances of the following type of
warnings:

fs/nfsd/nfsfh.h:79:33: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
fs/nfsd/state.h:763:33: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
fs/nfsd/state.h:669:33: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
fs/nfsd/state.h:549:33: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
fs/nfsd/xdr4.h:705:33: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
fs/nfsd/xdr4.h:678:33: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
Changes in v3:
 - Replace flexible-array member with a fixed-size array. (NeilBrown)

Changes in v2:
 - Use indices into `fh_raw`. (Christoph)
 - Remove union and flexible-array member `fh_fsid`. (Christoph)
 - Link: https://lore.kernel.org/linux-hardening/aEoKCuQ1YDs2Ivn0@kspp/

v1:
 - Link: https://lore.kernel.org/linux-hardening/aBp37ZXBJM09yAXp@kspp/

 fs/nfsd/nfsfh.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfsd/nfsfh.h b/fs/nfsd/nfsfh.h
index 5103c2f4d225..760e77f3630b 100644
--- a/fs/nfsd/nfsfh.h
+++ b/fs/nfsd/nfsfh.h
@@ -56,7 +56,7 @@ struct knfsd_fh {
 			u8		fh_auth_type;	/* deprecated */
 			u8		fh_fsid_type;
 			u8		fh_fileid_type;
-			u32		fh_fsid[]; /* flexible-array member */
+			u32		fh_fsid[NFS4_FHSIZE / 4 - 1];
 		};
 	};
 };
-- 
2.43.0