From 81dc4778cc2b8ecd8ce6a0312e701550df766bbb Mon Sep 17 00:00:00 2001
From: kib <kib@FreeBSD.org>
Date: Tue, 15 Sep 2020 21:55:21 +0000
Subject: [PATCH] Do not copy vp into f_data for DTYPE_VNODE files.

The pointer to vnode is already stored into f_vnode, so f_data can be
reused.  Fix all found users of f_data for DTYPE_VNODE.

Provide finit_vnode() helper to initialize file of DTYPE_VNODE type.

Reviewed by:	markj (previous version)
Discussed with:	freqlabs (openzfs chunk)
Tested by:	pho (previous version)
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D26346
---
 .../openzfs/module/os/freebsd/zfs/zfs_file_os.c       |  2 +-
 sys/fs/nfs/nfsdport.h                                 |  2 +-
 sys/kern/kern_descrip.c                               |  9 +++++++++
 sys/kern/vfs_syscalls.c                               | 11 ++---------
 sys/sys/file.h                                        |  1 +
 sys/ufs/ffs/ffs_alloc.c                               |  2 +-
 6 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_file_os.c b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_file_os.c
index ec7c04717c8..81796915f5d 100644
--- a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_file_os.c
+++ b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_file_os.c
@@ -239,7 +239,7 @@ zfs_file_fsync(zfs_file_t *fp, int flags)
 	if (fp->f_type != DTYPE_VNODE)
 		return (EINVAL);
 
-	v = fp->f_data;
+	v = fp->f_vnode;
 	return (zfs_vop_fsync(v));
 }
 
diff --git a/sys/fs/nfs/nfsdport.h b/sys/fs/nfs/nfsdport.h
index 28b155fba72..6d468219adf 100644
--- a/sys/fs/nfs/nfsdport.h
+++ b/sys/fs/nfs/nfsdport.h
@@ -94,7 +94,7 @@ struct nfsexstuff {
 #define	NFSLOCKHASH(f) 							\
 	(&nfslockhash[nfsrv_hashfh(f) % nfsrv_lockhashsize])
 
-#define	NFSFPVNODE(f)	((struct vnode *)((f)->f_data))
+#define	NFSFPVNODE(f)	((f)->f_vnode)
 #define	NFSFPCRED(f)	((f)->f_cred)
 #define	NFSFPFLAG(f)	((f)->f_flag)
 
diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index 3bfe913682e..6d67f9ce2e5 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -2622,6 +2622,15 @@ finit(struct file *fp, u_int flag, short type, void *data, struct fileops *ops)
 	atomic_store_rel_ptr((volatile uintptr_t *)&fp->f_ops, (uintptr_t)ops);
 }
 
+void
+finit_vnode(struct file *fp, u_int flag, void *data, struct fileops *ops)
+{
+	fp->f_seqcount[UIO_READ] = 1;
+	fp->f_seqcount[UIO_WRITE] = 1;
+	finit(fp, (flag & FMASK) | (fp->f_flag & FHASLOCK), DTYPE_VNODE,
+	    data, ops);
+}
+
 int
 fget_cap_locked(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
     struct file **fpp, struct filecaps *havecapsp)
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index f44b440be66..718ae706de5 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -1163,10 +1163,7 @@ kern_openat(struct thread *td, int fd, const char *path, enum uio_seg pathseg,
 	 */
 	if (fp->f_ops == &badfileops) {
 		KASSERT(vp->v_type != VFIFO, ("Unexpected fifo."));
-		fp->f_seqcount[UIO_READ] = 1;
-		fp->f_seqcount[UIO_WRITE] = 1;
-		finit(fp, (flags & FMASK) | (fp->f_flag & FHASLOCK),
-		    DTYPE_VNODE, vp, &vnops);
+		finit_vnode(fp, flags, NULL, &vnops);
 	}
 
 	VOP_UNLOCK(vp);
@@ -4138,7 +4135,6 @@ kern_getdirentries(struct thread *td, int fd, char *buf, size_t count,
 		vp = vp->v_mount->mnt_vnodecovered;
 		VREF(vp);
 		fp->f_vnode = vp;
-		fp->f_data = vp;
 		foffset = 0;
 		vput(tvp);
 		goto unionread;
@@ -4502,10 +4498,7 @@ sys_fhopen(struct thread *td, struct fhopen_args *uap)
 	td->td_dupfd = 0;
 #endif
 	fp->f_vnode = vp;
-	fp->f_seqcount[UIO_READ] = 1;
-	fp->f_seqcount[UIO_WRITE] = 1;
-	finit(fp, (fmode & FMASK) | (fp->f_flag & FHASLOCK), DTYPE_VNODE, vp,
-	    &vnops);
+	finit_vnode(fp, fmode, NULL, &vnops);
 	VOP_UNLOCK(vp);
 	if ((fmode & O_TRUNC) != 0) {
 		error = fo_truncate(fp, 0, td->td_ucred, td);
diff --git a/sys/sys/file.h b/sys/sys/file.h
index 10d48376446..7c69ee2ae98 100644
--- a/sys/sys/file.h
+++ b/sys/sys/file.h
@@ -268,6 +268,7 @@ fo_fill_kinfo_t	vn_fill_kinfo;
 int vn_fill_kinfo_vnode(struct vnode *vp, struct kinfo_file *kif);
 
 void finit(struct file *, u_int, short, void *, struct fileops *);
+void finit_vnode(struct file *, u_int, void *, struct fileops *);
 int fgetvp(struct thread *td, int fd, cap_rights_t *rightsp,
     struct vnode **vpp);
 int fgetvp_exec(struct thread *td, int fd, cap_rights_t *rightsp,
diff --git a/sys/ufs/ffs/ffs_alloc.c b/sys/ufs/ffs/ffs_alloc.c
index 9677a236cc7..7ad39e63bb1 100644
--- a/sys/ufs/ffs/ffs_alloc.c
+++ b/sys/ufs/ffs/ffs_alloc.c
@@ -3220,7 +3220,7 @@ sysctl_ffs_fsck(SYSCTL_HANDLER_ARGS)
 	if ((error = getvnode(td, cmd.handle,
 	    cap_rights_init(&rights, CAP_FSCK), &fp)) != 0)
 		return (error);
-	vp = fp->f_data;
+	vp = fp->f_vnode;
 	if (vp->v_type != VREG && vp->v_type != VDIR) {
 		fdrop(fp, td);
 		return (EINVAL);
-- 
2.45.0