git: 772258c89f28 - main - nfs_clrpcops.c: Fix acquisition of post-op attributes for link

The branch main has been updated by rmacklem:

URL: https://cgit.FreeBSD.org/src/commit/?id=772258c89f28501546844a60616211f44f55f4ce

commit 772258c89f28501546844a60616211f44f55f4ce
Author:     Rick Macklem <rmacklem@FreeBSD.org>
AuthorDate: 2025-05-16 00:27:14 +0000
Commit:     Rick Macklem <rmacklem@FreeBSD.org>
CommitDate: 2025-05-16 00:27:14 +0000

    nfs_clrpcops.c: Fix acquisition of post-op attributes for link
    
    Without this patch, the link RPC (done by nfsrpc_link()) did not
    acquire post link operation attributes for the file object for NFSv4.
    For some recent Linux NFSv4 servers that support delegations, this
    would result in the client's cached attribute for st_nlinks not being
    increased right away, because the delegation would indicate that the
    now stale cached attributes were still valid.
    
    This patch fixes the problem by acquiring post link attributes and
    updating the client's cached copy in the same manner as the NFSv3
    RPC did.
    
    Detected at the recent NFSv4 Bakeathon testing event.
    
    Applications will only be affected if they examine st_nlinks after
    a new hard link is created for a file object.
    
    MFC after:      2 weeks
---
 sys/fs/nfs/nfs_commonsubs.c     |  2 +-
 sys/fs/nfsclient/nfs_clrpcops.c | 40 +++++++++++++++++++++++++++-------------
 2 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/sys/fs/nfs/nfs_commonsubs.c b/sys/fs/nfs/nfs_commonsubs.c
index 39fa6f091eee..eeeb079a6aa7 100644
--- a/sys/fs/nfs/nfs_commonsubs.c
+++ b/sys/fs/nfs/nfs_commonsubs.c
@@ -254,7 +254,7 @@ static struct {
 	{ NFSV4OP_REMOVE, 1, "Remove", 6, },
 	{ NFSV4OP_REMOVE, 1, "Remove", 6, },
 	{ NFSV4OP_SAVEFH, 5, "Rename", 6, },
-	{ NFSV4OP_SAVEFH, 4, "Link", 4, },
+	{ NFSV4OP_SAVEFH, 6, "Link", 4, },
 	{ NFSV4OP_READDIR, 2, "Readdir", 7, },
 	{ NFSV4OP_READDIR, 2, "Readdir", 7, },
 	{ NFSV4OP_GETATTR, 1, "Getattr", 7, },
diff --git a/sys/fs/nfsclient/nfs_clrpcops.c b/sys/fs/nfsclient/nfs_clrpcops.c
index 0fb08df74a54..c1f94a65e506 100644
--- a/sys/fs/nfsclient/nfs_clrpcops.c
+++ b/sys/fs/nfsclient/nfs_clrpcops.c
@@ -3113,15 +3113,20 @@ nfsrpc_link(vnode_t dvp, vnode_t vp, char *name, int namelen,
 	(void)nfsm_fhtom(VFSTONFS(dvp->v_mount), nd, VTONFS(dvp)->n_fhp->nfh_fh,
 		VTONFS(dvp)->n_fhp->nfh_len, 0);
 	if (nd->nd_flag & ND_NFSV4) {
-		NFSM_BUILD(tl, u_int32_t *, NFSX_UNSIGNED);
-		*tl = txdr_unsigned(NFSV4OP_GETATTR);
-		NFSWCCATTR_ATTRBIT(&attrbits);
-		(void) nfsrv_putattrbit(nd, &attrbits);
-		nd->nd_flag |= ND_V4WCCATTR;
 		NFSM_BUILD(tl, u_int32_t *, NFSX_UNSIGNED);
 		*tl = txdr_unsigned(NFSV4OP_LINK);
 	}
 	(void) nfsm_strtom(nd, name, namelen);
+	if (nd->nd_flag & ND_NFSV4) {
+		NFSM_BUILD(tl, uint32_t *, NFSX_UNSIGNED);
+		*tl = txdr_unsigned(NFSV4OP_GETATTR);
+		NFSGETATTR_ATTRBIT(&attrbits);
+		(void)nfsrv_putattrbit(nd, &attrbits);
+		NFSM_BUILD(tl, uint32_t *, 2 * NFSX_UNSIGNED);
+		*tl++ = txdr_unsigned(NFSV4OP_RESTOREFH);
+		*tl = txdr_unsigned(NFSV4OP_GETATTR);
+		(void)nfsrv_putattrbit(nd, &attrbits);
+	}
 	error = nfscl_request(nd, vp, p, cred);
 	if (error)
 		return (error);
@@ -3130,19 +3135,28 @@ nfsrpc_link(vnode_t dvp, vnode_t vp, char *name, int namelen,
 		if (!error)
 			error = nfscl_wcc_data(nd, dvp, dnap, dattrflagp,
 			    NULL, NULL);
-	} else if ((nd->nd_flag & (ND_NFSV4 | ND_NOMOREDATA)) == ND_NFSV4) {
+	} else if (nd->nd_repstat == 0 && (nd->nd_flag & ND_NFSV4) != 0) {
 		/*
-		 * First, parse out the PutFH and Getattr result.
+		 * First and parse out the PutFH and Link results.
 		 */
-		NFSM_DISSECT(tl, u_int32_t *, 2 * NFSX_UNSIGNED);
-		if (!(*(tl + 1)))
-			NFSM_DISSECT(tl, u_int32_t *, 2 * NFSX_UNSIGNED);
-		if (*(tl + 1))
+		NFSM_DISSECT(tl, uint32_t *, 5 * NFSX_UNSIGNED +
+		    2 * NFSX_HYPER);
+		if (*(tl + 3))
 			nd->nd_flag |= ND_NOMOREDATA;
 		/*
-		 * Get the pre-op attributes.
+		 * Get the directory post-op attributes.
 		 */
-		error = nfscl_wcc_data(nd, dvp, dnap, dattrflagp, NULL, NULL);
+		if ((nd->nd_flag & ND_NOMOREDATA) == 0)
+			error = nfscl_postop_attr(nd, dnap, dattrflagp);
+		if (error == 0 && (nd->nd_flag & ND_NOMOREDATA) == 0) {
+			/* Get rid of the RestoreFH reply. */
+			NFSM_DISSECT(tl, uint32_t *, 2 * NFSX_UNSIGNED);
+			if (*(tl + 1))
+				nd->nd_flag |= ND_NOMOREDATA;
+		}
+		/* Get the file's post-op attributes. */
+		if (error == 0 && (nd->nd_flag & ND_NOMOREDATA) == 0)
+			error = nfscl_postop_attr(nd, nap, attrflagp);
 	}
 	if (nd->nd_repstat && !error)
 		error = nd->nd_repstat;