C++ VN_HOLD函数代码示例

vnode_t *
smb_lookuppathvptovp(smb_request_t *sr, char *path, vnode_t *startvp,
    vnode_t *rootvp)
{
	pathname_t pn;
	vnode_t *vp = NULL;
	int lookup_flags = FOLLOW;

	if (SMB_TREE_IS_CASEINSENSITIVE(sr))
		lookup_flags |= FIGNORECASE;

	(void) pn_alloc(&pn);

	if (pn_set(&pn, path) == 0) {
		VN_HOLD(startvp);
		if (rootvp != rootdir)
			VN_HOLD(rootvp);

		/* lookuppnvp should release the holds */
		if (lookuppnvp(&pn, NULL, lookup_flags, NULL, &vp,
		    rootvp, startvp, kcred) != 0) {
			pn_free(&pn);
			return (NULL);
		}
	}

	pn_free(&pn);
	return (vp);
}

/*
 * Lookup a rnode by fhandle.  Ignores rnodes that had failed recovery.
 * Returns NULL if no match.  If an rnode is returned, the reference count
 * on the master vnode is incremented.
 *
 * The caller must be holding the hash queue lock, either shared or exclusive.
 */
rnode4_t *
r4find(r4hashq_t *rhtp, nfs4_sharedfh_t *fh, struct vfs *vfsp)
{
	rnode4_t *rp;
	vnode_t *vp;

	ASSERT(RW_LOCK_HELD(&rhtp->r_lock));

	for (rp = rhtp->r_hashf; rp != (rnode4_t *)rhtp; rp = rp->r_hashf) {
		vp = RTOV4(rp);
		if (vp->v_vfsp == vfsp && SFH4_SAME(rp->r_fh, fh)) {

			mutex_enter(&rp->r_statelock);
			if (rp->r_flags & R4RECOVERR) {
				mutex_exit(&rp->r_statelock);
				continue;
			}
			mutex_exit(&rp->r_statelock);
#ifdef DEBUG
			r4_dup_check(rp, vfsp);
#endif
			if (rp->r_freef != NULL) {
				mutex_enter(&rp4freelist_lock);
				/*
				 * If the rnode is on the freelist,
				 * then remove it and use that reference
				 * as the new reference.  Otherwise,
				 * need to increment the reference count.
				 */
				if (rp->r_freef != NULL) {
					rp4_rmfree(rp);
					mutex_exit(&rp4freelist_lock);
				} else {
					mutex_exit(&rp4freelist_lock);
					VN_HOLD(vp);
				}
			} else
				VN_HOLD(vp);

			/*
			 * if root vnode, set v_flag to indicate that
			 */
			if (isrootfh(fh, rp)) {
				if (!(vp->v_flag & VROOT)) {
					mutex_enter(&vp->v_lock);
					vp->v_flag |= VROOT;
					mutex_exit(&vp->v_lock);
				}
			}
			return (rp);
		}
	}
	return (NULL);
}

int
xfs_cap_vset(
	vnode_t			*vp,
	void			*cap,
	size_t			size)
{
	posix_cap_xattr		*xattr_cap = cap;
	xfs_cap_set_t		xfs_cap;
	int			error;

	if (!cap)
		return -EINVAL;

	error = posix_cap_xattr_to_xfs(xattr_cap, size, &xfs_cap);
	if (error)
		return -error;

	VN_HOLD(vp);
	error = xfs_cap_allow_set(vp);
	if (error)
		goto out;

	VOP_ATTR_SET(vp, SGI_CAP_LINUX, (char *)&xfs_cap,
			sizeof(xfs_cap_set_t), ATTR_ROOT, sys_cred, error);
out:
	VN_RELE(vp);
	return -error;
}

/*
 * New Leaf driver open entry point.  We make a vnode and go through specfs
 * in order to obtain open close exclusions guarantees.  Note that we drop
 * OTYP_LYR if it was specified - we are going through specfs and it provides
 * last close semantics (FKLYR is provided to open(9E)).  Also, since
 * spec_open will drive attach via e_ddi_hold_devi_by_dev for a makespecvp
 * vnode with no SDIP_SET on the common snode, the dev_lopen caller no longer
 * needs to call ddi_hold_installed_driver.
 */
int
dev_lopen(dev_t *devp, int flag, int otype, struct cred *cred)
{
	struct vnode	*vp;
	int		error;
	struct vnode	*cvp;

	vp = makespecvp(*devp, (otype == OTYP_BLK) ? VBLK : VCHR);
	error = VOP_OPEN(&vp, flag | FKLYR, cred, NULL);
	if (error == 0) {
		/* Pick up the (possibly) new dev_t value. */
		*devp = vp->v_rdev;

		/*
		 * Place extra hold on the common vnode, which contains the
		 * open count, so that it is not destroyed by the VN_RELE of
		 * the shadow makespecvp vnode below.
		 */
		cvp = STOV(VTOCS(vp));
		VN_HOLD(cvp);
	}

	/* release the shadow makespecvp vnode. */
	VN_RELE(vp);
	return (error);
}

int
xfs_cap_vget(
	vnode_t		*vp,
	void		*cap,
	size_t		size)
{
	int		error;
	int		len = sizeof(xfs_cap_set_t);
	int		flags = ATTR_ROOT;
	xfs_cap_set_t	xfs_cap = { 0 };
	posix_cap_xattr	*xattr_cap = cap;
	char		*data = (char *)&xfs_cap;

	VN_HOLD(vp);
	if ((error = _MAC_VACCESS(vp, NULL, VREAD)))
		goto out;

	if (!size) {
		flags |= ATTR_KERNOVAL;
		data = NULL;
	}
	VOP_ATTR_GET(vp, SGI_CAP_LINUX, data, &len, flags, sys_cred, error);
	if (error)
		goto out;
	ASSERT(len == sizeof(xfs_cap_set_t));

	error = (size)? -posix_cap_xattr_size() :
			-posix_cap_xfs_to_xattr(&xfs_cap, xattr_cap, size);
out:
	VN_RELE(vp);
	return -error;
}

/*
 * Given a root znode, retrieve the associated .zfs directory.
 * Add a hold to the vnode and return it.
 */
vnode_t *
zfsctl_root(znode_t *zp)
{
	ASSERT(zfs_has_ctldir(zp));
	VN_HOLD(zp->z_zfsvfs->z_ctldir);
	return (zp->z_zfsvfs->z_ctldir);
}

STATIC int
linvfs_link(
	struct dentry	*old_dentry,
	struct inode	*dir,
	struct dentry	*dentry)
{
	struct inode	*ip;	/* inode of guy being linked to */
	vnode_t		*tdvp;	/* target directory for new name/link */
	vnode_t		*vp;	/* vp of name being linked */
	int		error;

	ip = old_dentry->d_inode;	/* inode being linked to */
	if (S_ISDIR(ip->i_mode))
		return -EPERM;

	tdvp = LINVFS_GET_VP(dir);
	vp = LINVFS_GET_VP(ip);

	VOP_LINK(tdvp, vp, dentry, NULL, error);
	if (!error) {
		VMODIFY(tdvp);
		VN_HOLD(vp);
		validate_fields(ip);
		d_instantiate(dentry, ip);
	}
	return -error;
}

/*
 * gfs_file_create(): create a new GFS file
 *
 *   size	- size of private data structure (v_data)
 *   pvp	- parent vnode (GFS directory)
 *   ops	- vnode operations vector
 *
 * In order to use this interface, the parent vnode must have been created by
 * gfs_dir_create(), and the private data stored in v_data must have a
 * 'gfs_file_t' as its first field.
 *
 * Given these constraints, this routine will automatically:
 *
 * 	- Allocate v_data for the vnode
 * 	- Initialize necessary fields in the vnode
 * 	- Hold the parent
 */
vnode_t *
gfs_file_create(size_t size, vnode_t *pvp, vnodeops_t *ops)
{
	gfs_file_t *fp;
	vnode_t *vp;

	/*
	 * Allocate vnode and internal data structure
	 */
	fp = kmem_zalloc(size, KM_SLEEP);
	vp = vn_alloc(KM_SLEEP);

	/*
	 * Set up various pointers
	 */
	fp->gfs_vnode = vp;
	fp->gfs_parent = pvp;
	vp->v_data = fp;
	fp->gfs_size = size;
	fp->gfs_type = GFS_FILE;

	/*
	 * Initialize vnode and hold parent.
	 */
	vn_setops(vp, ops);
	if (pvp) {
		VN_SET_VFS_TYPE_DEV(vp, pvp->v_vfsp, VREG, 0);
		VN_HOLD(pvp);
	}

	return (vp);
}

static int
zfsctl_unmount_snap(zfs_snapentry_t *sep, int fflags, cred_t *cr)
{
	vnode_t *svp = sep->se_root;
	int error;

	ASSERT(vn_ismntpt(svp));

	/* this will be dropped by dounmount() */
	if ((error = vn_vfswlock(svp)) != 0)
		return (error);

	VN_HOLD(svp);
	error = dounmount(vn_mountedvfs(svp), fflags, cr);
	if (error) {
		VN_RELE(svp);
		return (error);
	}

	/*
	 * We can't use VN_RELE(), as that will try to invoke
	 * zfsctl_snapdir_inactive(), which would cause us to destroy
	 * the sd_lock mutex held by our caller.
	 */
	ASSERT(svp->v_count == 1);
	gfs_vop_inactive(svp, cr, NULL);

	kmem_free(sep->se_name, strlen(sep->se_name) + 1);
	kmem_free(sep, sizeof (zfs_snapentry_t));

	return (0);
}

/*
 * find root of smbfs
 */
static int
smbfs_root(vfs_t *vfsp, vnode_t **vpp)
{
	smbmntinfo_t	*smi;
	vnode_t		*vp;

	smi = VFTOSMI(vfsp);

	if (curproc->p_zone != smi->smi_zone_ref.zref_zone)
		return (EPERM);

	if (smi->smi_flags & SMI_DEAD || vfsp->vfs_flag & VFS_UNMOUNTED)
		return (EIO);

	/*
	 * The root vp is created in mount and held
	 * until unmount, so this is paranoia.
	 */
	if (smi->smi_root == NULL)
		return (EIO);

	/* Just take a reference and return it. */
	vp = SMBTOV(smi->smi_root);
	VN_HOLD(vp);
	*vpp = vp;

	return (0);
}

/*
 * Holds on dvp and rootvp (if not rootdir) are required by lookuppnvp()
 * and will be released within lookuppnvp().
 */
static int
smb_pathname_lookup(pathname_t *pn, pathname_t *rpn, int flags,
    vnode_t **vp, vnode_t *rootvp, vnode_t *dvp, smb_attr_t *attr, cred_t *cred)
{
	int err;

	*vp = NULL;
	VN_HOLD(dvp);
	if (rootvp != rootdir)
		VN_HOLD(rootvp);

	err = lookuppnvp(pn, rpn, flags, NULL, vp, rootvp, dvp, cred);
	if ((err == 0) && (attr != NULL))
		(void) smb_vop_getattr(*vp, NULL, attr, 0, kcred);

	return (err);
}

/*
 * Given a root znode, retrieve the associated .zfs directory.
 * Add a hold to the vnode and return it.
 */
vnode_t *
zfsctl_root(znode_t *zp)
{
	ASSERT(zfs_has_ctldir(zp));
	if (VN_HOLD(zp->z_zfsvfs->z_ctldir) != NULL)
		return (zp->z_zfsvfs->z_ctldir);
	else
		return NULL;
}

/* ARGSUSED */
static int
fdroot(vfs_t *vfsp, vnode_t **vpp)
{
	vnode_t *vp = (vnode_t *)vfsp->vfs_data;

	VN_HOLD(vp);
	*vpp = vp;
	return (0);
}

/*
 * Lookup the user file name from a given vp, using a specific credential.
 */
int
lookuppnatcred(
	struct pathname *pnp,		/* pathname to lookup */
	struct pathname *rpnp,		/* if non-NULL, return resolved path */
	int followlink,			/* (don't) follow sym links */
	vnode_t **dirvpp,		/* ptr for parent vnode */
	vnode_t **compvpp,		/* ptr for entry vnode */
	vnode_t *startvp,		/* start search from this vp */
	cred_t *cr)			/* user credential */
{
	vnode_t *vp;	/* current directory vp */
	vnode_t *rootvp;
	proc_t *p = curproc;

	if (pnp->pn_pathlen == 0)
		return (ENOENT);

	mutex_enter(&p->p_lock);	/* for u_rdir and u_cdir */
	if ((rootvp = PTOU(p)->u_rdir) == NULL)
		rootvp = rootdir;
	else if (rootvp != rootdir)	/* no need to VN_HOLD rootdir */
		VN_HOLD(rootvp);

	if (pnp->pn_path[0] == '/') {
		vp = rootvp;
	} else {
		vp = (startvp == NULL) ? PTOU(p)->u_cdir : startvp;
	}
	VN_HOLD(vp);
	mutex_exit(&p->p_lock);

	/*
	 * Skip over leading slashes
	 */
	if (pnp->pn_path[0] == '/') {
		do {
			pnp->pn_path++;
			pnp->pn_pathlen--;
		} while (pnp->pn_path[0] == '/');
	}

	return (lookuppnvp(pnp, rpnp, followlink, dirvpp,
	    compvpp, rootvp, vp, cr));
}

/*ARGSUSED*/
int
spec_sync(struct vfs *vfsp,
	short	flag,
	struct cred *cr)
{
	struct snode *sync_list;
	register struct snode **spp, *sp, *spnext;
	register struct vnode *vp;

	if (mutex_tryenter(&spec_syncbusy) == 0)
		return (0);

	if (flag & SYNC_ATTR) {
		mutex_exit(&spec_syncbusy);
		return (0);
	}
	mutex_enter(&stable_lock);
	sync_list = NULL;
	/*
	 * Find all the snodes that are dirty and add them to the sync_list
	 */
	for (spp = stable; spp < &stable[STABLESIZE]; spp++) {
		for (sp = *spp; sp != NULL; sp = sp->s_next) {
			vp = STOV(sp);
			/*
			 * Don't bother sync'ing a vp if it's
			 * part of a virtual swap device.
			 */
			if (IS_SWAPVP(vp))
				continue;

			if (vp->v_type == VBLK && vn_has_cached_data(vp)) {
				/*
				 * Prevent vp from going away before we
				 * we get a chance to do a VOP_PUTPAGE
				 * via sync_list processing
				 */
				VN_HOLD(vp);
				sp->s_list = sync_list;
				sync_list = sp;
			}
		}
	}
	mutex_exit(&stable_lock);
	/*
	 * Now write out all the snodes we marked asynchronously.
	 */
	for (sp = sync_list; sp != NULL; sp = spnext) {
		spnext = sp->s_list;
		vp = STOV(sp);
		(void) VOP_PUTPAGE(vp, (offset_t)0, (uint_t)0, B_ASYNC, cr);
		VN_RELE(vp);		/* Release our hold on vnode */
	}
	mutex_exit(&spec_syncbusy);
	return (0);
}