linux-kernel - [PATCH v3 35/38] nfsd: add the filehandle to returned attributes in CB

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Message-Id: <20250924-dir-deleg-v3-35-9f3af8bc5c40@kernel.org>
Date: Wed, 24 Sep 2025 14:06:21 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Alexander Viro <viro@...iv.linux.org.uk>, 
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
 Chuck Lever <chuck.lever@...cle.com>, 
 Alexander Aring <alex.aring@...il.com>, 
 Trond Myklebust <trondmy@...nel.org>, Anna Schumaker <anna@...nel.org>, 
 Steve French <sfrench@...ba.org>, 
 Ronnie Sahlberg <ronniesahlberg@...il.com>, 
 Shyam Prasad N <sprasad@...rosoft.com>, Tom Talpey <tom@...pey.com>, 
 Bharath SM <bharathsm@...rosoft.com>, NeilBrown <neil@...wn.name>, 
 Olga Kornievskaia <okorniev@...hat.com>, Dai Ngo <Dai.Ngo@...cle.com>, 
 Jonathan Corbet <corbet@....net>, Amir Goldstein <amir73il@...il.com>, 
 Miklos Szeredi <miklos@...redi.hu>, Paulo Alcantara <pc@...guebit.org>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 "Rafael J. Wysocki" <rafael@...nel.org>, Danilo Krummrich <dakr@...nel.org>, 
 David Howells <dhowells@...hat.com>, Tyler Hicks <code@...icks.com>, 
 Namjae Jeon <linkinjeon@...nel.org>, Steve French <smfrench@...il.com>, 
 Sergey Senozhatsky <senozhatsky@...omium.org>, 
 Carlos Maiolino <cem@...nel.org>, Steven Rostedt <rostedt@...dmis.org>, 
 Masami Hiramatsu <mhiramat@...nel.org>, 
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, 
 Paulo Alcantara <pc@...guebit.org>
Cc: Rick Macklem <rick.macklem@...il.com>, linux-fsdevel@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-nfs@...r.kernel.org, 
 linux-cifs@...r.kernel.org, samba-technical@...ts.samba.org, 
 linux-doc@...r.kernel.org, netfs@...ts.linux.dev, ecryptfs@...r.kernel.org, 
 linux-unionfs@...r.kernel.org, linux-xfs@...r.kernel.org, 
 linux-trace-kernel@...r.kernel.org, Jeff Layton <jlayton@...nel.org>
Subject: [PATCH v3 35/38] nfsd: add the filehandle to returned attributes
 in CB_NOTIFY

nfsd's usual fh_compose routine requires a svc_export and fills out a
svc_fh. In the context of a CB_NOTIFY there is no such export to
consult.

Add a new routine that composes a filehandle with only a parent
filehandle and nfs4_file. Use that to fill out the fhandle field in the
nfsd4_fattr_args.

Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
 fs/nfsd/nfs4xdr.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 822a9d47dd88df579e4f57f04dd6737653f71c94..11b622aca5111502b483f269b1fce6a684804645 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3763,6 +3763,39 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct xdr_stream *xdr,
 	goto out;
 }

+static bool
+setup_notify_fhandle(struct dentry *dentry, struct nfs4_file *fi,
+		     struct nfsd4_fattr_args *args)
+{
+	int fileid_type, fsid_len, maxsize, flags = 0;
+	struct knfsd_fh *fhp = &args->fhandle;
+	struct inode *inode = d_inode(dentry);
+	struct inode *parent = NULL;
+	struct fid *fid;
+
+	fsid_len = key_len(fi->fi_fhandle.fh_fsid_type);
+	fhp->fh_size = 4 + fsid_len;
+
+	/* Copy first 4 bytes + fsid */
+	memcpy(&fhp->fh_raw, &fi->fi_fhandle.fh_raw, fhp->fh_size);
+
+	fid = (struct fid *)(fh_fsid(fhp) + fsid_len/4);
+	maxsize = (NFS4_FHSIZE - fhp->fh_size)/4;
+
+	if (fi->fi_connectable && !S_ISDIR(inode->i_mode)) {
+		parent = d_inode(fi->fi_deleg_file->nf_file->f_path.dentry);
+		flags = EXPORT_FH_CONNECTABLE;
+	}
+
+	fileid_type = exportfs_encode_inode_fh(inode, fid, &maxsize, parent, flags);
+	if (fileid_type < 0)
+		return false;
+
+	fhp->fh_fileid_type = fileid_type;
+	fhp->fh_size += maxsize * 4;
+	return true;
+}
+
 #define CB_NOTIFY_STATX_REQUEST_MASK (STATX_BASIC_STATS   | \
 				      STATX_BTIME	  | \
 				      STATX_CHANGE_COOKIE)
@@ -3811,6 +3844,9 @@ nfsd4_setup_notify_entry4(struct notify_entry4 *ne, struct xdr_stream *xdr,
 		      FATTR4_WORD1_TIME_METADATA | FATTR4_WORD1_TIME_MODIFY;
 	attrmask[2] = 0;

+	if (setup_notify_fhandle(dentry, fi, &args))
+		attrmask[0] |= FATTR4_WORD0_FILEHANDLE;
+
 	if (args.stat.result_mask & STATX_BTIME)
 		attrmask[1] |= FATTR4_WORD1_TIME_CREATE;

-- 
2.51.0