linux-kernel - [PATCH v2 6/6] nfsd: Implement NFSv4 FATTR4_CASE_INSENSITIVE and FATTR4_CASE

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Message-ID: <20251211152116.480799-7-cel@kernel.org>
Date: Thu, 11 Dec 2025 10:21:16 -0500
From: Chuck Lever <cel@...nel.org>
To: Al Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>
Cc: <linux-fsdevel@...r.kernel.org>,
	linux-ext4@...r.kernel.org,
	<linux-nfs@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	hirofumi@...l.parknet.co.jp,
	almaz.alexandrovich@...agon-software.com,
	tytso@....edu,
	adilger.kernel@...ger.ca,
	Volker.Lendecke@...net.de,
	Chuck Lever <chuck.lever@...cle.com>
Subject: [PATCH v2 6/6] nfsd: Implement NFSv4 FATTR4_CASE_INSENSITIVE and FATTR4_CASE_PRESERVING

From: Chuck Lever <chuck.lever@...cle.com>

Replace the hard-coded values for the NFSv4 case_insensitive and
case_preserving attributes with dynamic values retrieved from the
underlying filesystem via vfs_get_case_info().

This allows NFSv4 clients to discover the actual case sensitivity
behavior of exported filesystems, including per-directory settings
for filesystems like ext4 with casefold support.

Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
---
 fs/nfsd/nfs4xdr.c | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 67bb9c0b9fcb..0c51d390d995 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2933,6 +2933,8 @@ struct nfsd4_fattr_args {
 	u32			rdattr_err;
 	bool			contextsupport;
 	bool			ignore_crossmnt;
+	bool			case_insensitive;
+	bool			case_preserving;
 };
 
 typedef __be32(*nfsd4_enc_attr)(struct xdr_stream *xdr,
@@ -3131,6 +3133,18 @@ static __be32 nfsd4_encode_fattr4_acl(struct xdr_stream *xdr,
 	return nfs_ok;
 }
 
+static __be32 nfsd4_encode_fattr4_case_insensitive(struct xdr_stream *xdr,
+					const struct nfsd4_fattr_args *args)
+{
+	return nfsd4_encode_bool(xdr, args->case_insensitive);
+}
+
+static __be32 nfsd4_encode_fattr4_case_preserving(struct xdr_stream *xdr,
+					const struct nfsd4_fattr_args *args)
+{
+	return nfsd4_encode_bool(xdr, args->case_preserving);
+}
+
 static __be32 nfsd4_encode_fattr4_filehandle(struct xdr_stream *xdr,
 					     const struct nfsd4_fattr_args *args)
 {
@@ -3482,8 +3496,8 @@ static const nfsd4_enc_attr nfsd4_enc_fattr4_encode_ops[] = {
 	[FATTR4_ACLSUPPORT]		= nfsd4_encode_fattr4_aclsupport,
 	[FATTR4_ARCHIVE]		= nfsd4_encode_fattr4__noop,
 	[FATTR4_CANSETTIME]		= nfsd4_encode_fattr4__true,
-	[FATTR4_CASE_INSENSITIVE]	= nfsd4_encode_fattr4__false,
-	[FATTR4_CASE_PRESERVING]	= nfsd4_encode_fattr4__true,
+	[FATTR4_CASE_INSENSITIVE]	= nfsd4_encode_fattr4_case_insensitive,
+	[FATTR4_CASE_PRESERVING]	= nfsd4_encode_fattr4_case_preserving,
 	[FATTR4_CHOWN_RESTRICTED]	= nfsd4_encode_fattr4__true,
 	[FATTR4_FILEHANDLE]		= nfsd4_encode_fattr4_filehandle,
 	[FATTR4_FILEID]			= nfsd4_encode_fattr4_fileid,
@@ -3669,8 +3683,9 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct xdr_stream *xdr,
 		if (err)
 			goto out_nfserr;
 	}
-	if ((attrmask[0] & (FATTR4_WORD0_FILEHANDLE | FATTR4_WORD0_FSID)) &&
-	    !fhp) {
+	if ((attrmask[0] & (FATTR4_WORD0_FILEHANDLE | FATTR4_WORD0_FSID |
+			    FATTR4_WORD0_CASE_INSENSITIVE |
+			    FATTR4_WORD0_CASE_PRESERVING)) && !fhp) {
 		tempfh = kmalloc(sizeof(struct svc_fh), GFP_KERNEL);
 		status = nfserr_jukebox;
 		if (!tempfh)
@@ -3682,6 +3697,13 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct xdr_stream *xdr,
 		args.fhp = tempfh;
 	} else
 		args.fhp = fhp;
+	if (attrmask[0] & (FATTR4_WORD0_CASE_INSENSITIVE |
+			   FATTR4_WORD0_CASE_PRESERVING)) {
+		status = nfsd_get_case_info(args.fhp, &args.case_insensitive,
+					    &args.case_preserving);
+		if (status != nfs_ok)
+			goto out;
+	}
 
 	if (attrmask[0] & FATTR4_WORD0_ACL) {
 		err = nfsd4_get_nfs4_acl(rqstp, dentry, &args.acl);
-- 
2.52.0