C++ rw_exit函数代码示例

/*
 * Look up an entry in a directory.
 *
 * NOTE: '.' and '..' are handled as special cases because
 *	no directory entries are actually stored for them.  If this is
 *	the root of a filesystem, then '.zfs' is also treated as a
 *	special pseudo-directory.
 */
int
zfs_dirlook(znode_t *dzp, char *name, vnode_t **vpp)
{
	zfs_dirlock_t *dl;
	znode_t *zp;
	int error = 0;

	if (name[0] == 0 || (name[0] == '.' && name[1] == 0)) {
		*vpp = ZTOV(dzp);
		VN_HOLD(*vpp);
	} else if (name[0] == '.' && name[1] == '.' && name[2] == 0) {
		zfsvfs_t *zfsvfs = dzp->z_zfsvfs;
		/*
		 * If we are a snapshot mounted under .zfs, return
		 * the vp for the snapshot directory.
		 */
		if (dzp->z_phys->zp_parent == dzp->z_id &&
		    zfsvfs->z_parent != zfsvfs) {
			error = zfsctl_root_lookup(zfsvfs->z_parent->z_ctldir,
			    "snapshot", vpp, NULL, 0, NULL, kcred);
			return (error);
		}
		rw_enter(&dzp->z_parent_lock, RW_READER);
		error = zfs_zget(zfsvfs, dzp->z_phys->zp_parent, &zp);
		if (error == 0)
			*vpp = ZTOV(zp);
		rw_exit(&dzp->z_parent_lock);
	} else if (zfs_has_ctldir(dzp) && strcmp(name, ZFS_CTLDIR_NAME) == 0) {
		*vpp = zfsctl_root(dzp);
	} else {
		error = zfs_dirent_lock(&dl, dzp, name, &zp, ZEXISTS | ZSHARED);
		if (error == 0) {
			*vpp = ZTOV(zp);
			zfs_dirent_unlock(dl);
			dzp->z_zn_prefetch = B_TRUE; /* enable prefetching */
		}
	}

	return (error);
}

int
rds_open_transport_driver()
{
	int ret = 0;

	rw_enter(&rds_transport_lock, RW_WRITER);
	if (rds_transport_handle != NULL) {
		/*
		 * Someone beat us to it.
		 */
		goto done;
	}

	if (ibt_hw_is_present() == 0) {
		ret = ENODEV;
		goto done;
	}

	if (rds_li == NULL) {
		ret = EPROTONOSUPPORT;
		goto done;
	}

	ret = ldi_open_by_name("/devices/ib/[email protected]:rdsib",
	    FREAD | FWRITE, kcred, &rds_transport_handle, rds_li);
	if (ret != 0) {
		ret = EPROTONOSUPPORT;
		rds_transport_handle = NULL;
		goto done;
	}

	ret = rds_transport_ops->rds_transport_open_ib();
	if (ret != 0) {
		(void) ldi_close(rds_transport_handle, FNDELAY, kcred);
		rds_transport_handle = NULL;
	}
done:
	rw_exit(&rds_transport_lock);
	return (ret);
}

static int
splat_rwlock_test4_type(taskq_t *tq, rw_priv_t *rwp, int expected_rc,
			krw_t holder_type, krw_t try_type)
{
	int id, rc = 0;

	/* Schedule a task function which will try and acquire the rwlock
	 * using type try_type while the rwlock is being held as holder_type.
	 * The result must match expected_rc for the test to pass */
	rwp->rw_rc = -EINVAL;
	rwp->rw_type = try_type;

	if (holder_type == RW_WRITER || holder_type == RW_READER)
		rw_enter(&rwp->rw_rwlock, holder_type);

	id = taskq_dispatch(tq, splat_rwlock_test4_func, rwp, TQ_SLEEP);
	if (id == 0) {
		splat_vprint(rwp->rw_file, SPLAT_RWLOCK_TEST4_NAME, "%s",
			     "taskq_dispatch() failed\n");
		rc = -EINVAL;
		goto out;
	}

	taskq_wait_id(tq, id);

	if (rwp->rw_rc != expected_rc)
		rc = -EINVAL;

	splat_vprint(rwp->rw_file, SPLAT_RWLOCK_TEST4_NAME,
		     "%srw_tryenter(%s) returned %d (expected %d) when %s\n",
		     rc ? "Fail " : "", splat_rwlock_test4_name(try_type),
		     rwp->rw_rc, expected_rc,
		     splat_rwlock_test4_name(holder_type));
out:
	if (holder_type == RW_WRITER || holder_type == RW_READER)
		rw_exit(&rwp->rw_rwlock);

	return rc;
}

/*
 * Install an exec module.
 */
static int
mod_installexec(struct modlexec *modl, struct modlinkage *modlp)
{
	struct execsw *eswp;
	struct modctl *mcp;
	char *modname;
	char *magic;
	size_t magic_size;

	/*
	 * See if execsw entry is already allocated.  Can't use findexectype()
	 * because we may get a recursive call to here.
	 */

	if ((eswp = findexecsw(modl->exec_execsw->exec_magic)) == NULL) {
		mcp = mod_getctl(modlp);
		ASSERT(mcp != NULL);
		modname = mcp->mod_modname;
		magic = modl->exec_execsw->exec_magic;
		magic_size = modl->exec_execsw->exec_maglen;
		if ((eswp = allocate_execsw(modname, magic, magic_size)) ==
		    NULL) {
			printf("no unused entries in 'execsw'\n");
			return (ENOSPC);
		}
	}
	if (eswp->exec_func != NULL) {
		printf("exec type %x is already installed\n",
			*eswp->exec_magic);
			return (EBUSY);		 /* it's already there! */
	}

	rw_enter(eswp->exec_lock, RW_WRITER);
	eswp->exec_func = modl->exec_execsw->exec_func;
	eswp->exec_core = modl->exec_execsw->exec_core;
	rw_exit(eswp->exec_lock);

	return (0);
}

/*
 * Query domain table by index, returning domain string
 *
 * Returns a pointer from an avl node of the domain string.
 *
 */
const char *
zfs_fuid_find_by_idx(zfsvfs_t *zfsvfs, uint32_t idx)
{
	char *domain;

	if (idx == 0 || !zfsvfs->z_use_fuids)
		return (NULL);

	if (!zfsvfs->z_fuid_loaded)
		zfs_fuid_init(zfsvfs);

	rw_enter(&zfsvfs->z_fuid_lock, RW_READER);

	if (zfsvfs->z_fuid_obj || zfsvfs->z_fuid_dirty)
		domain = zfs_fuid_idx_domain(&zfsvfs->z_fuid_idx, idx);
	else
		domain = nulldomain;
	rw_exit(&zfsvfs->z_fuid_lock);

	ASSERT(domain);
	return (domain);
}

void
dsl_dir_stats(dsl_dir_t *dd, nvlist_t *nv)
{
	mutex_enter(&dd->dd_lock);
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USED,
	    dd->dd_phys->dd_used_bytes);
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_QUOTA, dd->dd_phys->dd_quota);
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_RESERVATION,
	    dd->dd_phys->dd_reserved);
	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_COMPRESSRATIO,
	    dd->dd_phys->dd_compressed_bytes == 0 ? 100 :
	    (dd->dd_phys->dd_uncompressed_bytes * 100 /
	    dd->dd_phys->dd_compressed_bytes));
	if (dd->dd_phys->dd_flags & DD_FLAG_USED_BREAKDOWN) {
		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USEDSNAP,
		    dd->dd_phys->dd_used_breakdown[DD_USED_SNAP]);
		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USEDDS,
		    dd->dd_phys->dd_used_breakdown[DD_USED_HEAD]);
		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USEDREFRESERV,
		    dd->dd_phys->dd_used_breakdown[DD_USED_REFRSRV]);
		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_USEDCHILD,
		    dd->dd_phys->dd_used_breakdown[DD_USED_CHILD] +
		    dd->dd_phys->dd_used_breakdown[DD_USED_CHILD_RSRV]);
	}
	mutex_exit(&dd->dd_lock);

	rw_enter(&dd->dd_pool->dp_config_rwlock, RW_READER);
	if (dsl_dir_is_clone(dd)) {
		dsl_dataset_t *ds;
		char buf[MAXNAMELEN];

		VERIFY(0 == dsl_dataset_hold_obj(dd->dd_pool,
		    dd->dd_phys->dd_origin_obj, FTAG, &ds));
		dsl_dataset_name(ds, buf);
		dsl_dataset_rele(ds, FTAG);
		dsl_prop_nvlist_add_string(nv, ZFS_PROP_ORIGIN, buf);
	}
	rw_exit(&dd->dd_pool->dp_config_rwlock);
}

/*
 * Selects the raidz operation for raidz_map
 * If rm_ops is set to NULL original raidz implementation will be used
 */
void
vdev_raidz_math_get_ops(raidz_map_t *rm)
{
	rw_enter(&vdev_raidz_impl_lock, RW_READER);

	rm->rm_ops = vdev_raidz_used_impl;

#if !defined(_KERNEL)
	if (zfs_vdev_raidz_impl == IMPL_CYCLE) {
		static size_t cycle_impl_idx = 0;
		size_t idx;
		/*
		 * Cycle through all supported new implementations, and
		 * when idx == raidz_supp_impl_cnt, use the original
		 */
		idx = (++cycle_impl_idx) % (raidz_supp_impl_cnt + 1);
		rm->rm_ops = raidz_supp_impl[idx];
	}
#endif

	rw_exit(&vdev_raidz_impl_lock);
}

/*
 * returns ENOENT, EIO, or 0.
 *
 * This interface will allocate a blank spill dbuf when a spill blk
 * doesn't already exist on the dnode.
 *
 * if you only want to find an already existing spill db, then
 * dmu_spill_hold_existing() should be used.
 */
int
dmu_spill_hold_by_dnode(dnode_t *dn, uint32_t flags, void *tag, dmu_buf_t **dbp)
{
	dmu_buf_impl_t *db = NULL;
	int err;

	if ((flags & DB_RF_HAVESTRUCT) == 0)
		rw_enter(&dn->dn_struct_rwlock, RW_READER);

	db = dbuf_hold(dn, DMU_SPILL_BLKID, tag);

	if ((flags & DB_RF_HAVESTRUCT) == 0)
		rw_exit(&dn->dn_struct_rwlock);

	ASSERT(db != NULL);
	err = dbuf_read(db, NULL, flags);
	if (err == 0)
		*dbp = &db->db;
	else
		dbuf_rele(db, tag);
	return (err);
}

static int
splat_rwlock_test5(struct file *file, void *arg)
{
	rw_priv_t *rwp;
	int rc = -EINVAL;

	rwp = (rw_priv_t *)kmalloc(sizeof(*rwp), GFP_KERNEL);
	if (rwp == NULL)
		return -ENOMEM;

	splat_init_rw_priv(rwp, file);

	rw_enter(&rwp->rw_rwlock, RW_WRITER);
	if (!RW_WRITE_HELD(&rwp->rw_rwlock)) {
		splat_vprint(file, SPLAT_RWLOCK_TEST5_NAME,
			     "rwlock should be write lock: %d\n",
			     RW_WRITE_HELD(&rwp->rw_rwlock));
		goto out;
	}

	rw_downgrade(&rwp->rw_rwlock);
	if (!RW_READ_HELD(&rwp->rw_rwlock)) {
		splat_vprint(file, SPLAT_RWLOCK_TEST5_NAME,
			     "rwlock should be read lock: %d\n",
			     RW_READ_HELD(&rwp->rw_rwlock));
		goto out;
	}

	rc = 0;
	splat_vprint(file, SPLAT_RWLOCK_TEST5_NAME, "%s",
		     "rwlock properly downgraded\n");
out:
	rw_exit(&rwp->rw_rwlock);
	rw_destroy(&rwp->rw_rwlock);
	kfree(rwp);

	return rc;
}

int64_t pap_putmsg(int fildes, struct strbuf * ctlptr, struct strbuf
                   * dataptr, int *flagsp)
{
    struct strbuf kctlptr;
    dl_promiscon_req_t *kpromiscon;

    inc_refcnt();

    dcmn_err((CE_CONT, "putmsg() syscall.\n"));

    rw_enter(&config_rwlock, RW_READER);

    if (!config.ppromisc ||
        copyin(ctlptr, &kctlptr, sizeof(struct strbuf)) != 0)
        goto err;

    mutex_enter(&promisc_lock);

    kpromiscon = (dl_promiscon_req_t *) kmem_alloc(kctlptr.len, KM_SLEEP);
    if (!kpromiscon)
        goto err_and_unlock;

    if (copyin(kctlptr.buf, kpromiscon, kctlptr.len) != 0)
        goto err_and_free;

    check_promisc(fildes, kpromiscon);

  err_and_free:
    kmem_free(kpromiscon, kctlptr.len);
  err_and_unlock:
    mutex_exit(&promisc_lock);
  err:

    rw_exit(&config_rwlock);
    dec_refcnt();

    return syscalls[PUTMSG].sc(fildes, ctlptr, dataptr, flagsp);
}

/*
 * increase statefile size
 */
static int
cpr_grow_statefile(vnode_t *vp, u_longlong_t newsize)
{
	extern uchar_t cpr_pagecopy[];
	struct inode *ip = VTOI(vp);
	u_longlong_t offset;
	int error, increase;
	ssize_t resid;

	rw_enter(&ip->i_contents, RW_READER);
	increase = (ip->i_size < newsize);
	offset = ip->i_size;
	rw_exit(&ip->i_contents);

	if (increase == 0)
		return (0);

	/*
	 * write to each logical block to reserve disk space
	 */
	error = 0;
	cpr_pagecopy[0] = '1';
	for (; offset < newsize; offset += ip->i_fs->fs_bsize) {
		if (error = vn_rdwr(UIO_WRITE, vp, (caddr_t)cpr_pagecopy,
		    ip->i_fs->fs_bsize, (offset_t)offset, UIO_SYSSPACE, 0,
		    (rlim64_t)MAXOFF_T, CRED(), &resid)) {
			if (error == ENOSPC) {
				cpr_err(CE_WARN, "error %d while reserving "
				    "disk space for statefile %s\n"
				    "wanted %lld bytes, file is %lld short",
				    error, cpr_cprconfig_to_path(),
				    newsize, newsize - offset);
			}
			break;
		}
	}
	return (error);
}

/*
 * Remove an exec module.
 */
static int
mod_removeexec(struct modlexec *modl, struct modlinkage *modlp)
{
	struct execsw *eswp;
	struct modctl *mcp;
	char *modname;

	eswp = findexecsw(modl->exec_execsw->exec_magic);
	if (eswp == NULL) {
		mcp = mod_getctl(modlp);
		ASSERT(mcp != NULL);
		modname = mcp->mod_modname;
		cmn_err(CE_WARN, uninstall_err, modname);
		return (EINVAL);
	}
	if (moddebug & MODDEBUG_NOAUL_EXEC ||
	    !rw_tryenter(eswp->exec_lock, RW_WRITER))
		return (EBUSY);
	eswp->exec_func = NULL;
	eswp->exec_core = NULL;
	rw_exit(eswp->exec_lock);
	return (0);
}

static void
s1394_cmp_impr_recv_read_request(cmd1394_cmd_t *req)
{
	s1394_hal_t	*hal = req->cmd_callback_arg;
	s1394_cmp_hal_t *cmp = &hal->hal_cmp;

	TNF_PROBE_0_DEBUG(s1394_cmp_impr_recv_read_request_enter,
	    S1394_TNF_SL_CMP_STACK, "");

	if (req->cmd_type != CMD1394_ASYNCH_RD_QUAD) {
		req->cmd_result = IEEE1394_RESP_TYPE_ERROR;
	} else {
		rw_enter(&cmp->cmp_impr_rwlock, RW_READER);
		req->cmd_u.q.quadlet_data = cmp->cmp_impr_val;
		rw_exit(&cmp->cmp_impr_rwlock);
		req->cmd_result = IEEE1394_RESP_COMPLETE;
	}

	(void) s1394_send_response(hal, req);

	TNF_PROBE_0_DEBUG(s1394_cmp_impr_recv_read_request_exit,
	    S1394_TNF_SL_CMP_STACK, "");
}

static int
nfs4_active_reclaim(void)
{
	int freed;
	int index;
	rnode4_t *rp;

#ifdef DEBUG
	clstat4_debug.a_reclaim.value.ui64++;
#endif
	freed = 0;
	for (index = 0; index < rtable4size; index++) {
		rw_enter(&rtable4[index].r_lock, RW_READER);
		for (rp = rtable4[index].r_hashf;
		    rp != (rnode4_t *)(&rtable4[index]);
		    rp = rp->r_hashf) {
			if (nfs4_active_data_reclaim(rp))
				freed = 1;
		}
		rw_exit(&rtable4[index].r_lock);
	}
	return (freed);
}

static int
filemon_wrapper_execve(struct lwp * l, struct sys_execve_args * uap,
    register_t * retval)
{
	char fname[MAXPATHLEN];
	int ret;
	int error;
	size_t done;
	struct filemon *filemon;
	
	error = copyinstr(SCARG(uap, path), fname, sizeof(fname), &done);

	if ((ret = sys_execve(l, uap, retval)) == EJUSTRETURN && error == 0) {
		filemon = filemon_lookup(curproc);

		if (filemon) {
			filemon_printf(filemon, "E %d %s\n",
			    curproc->p_pid, fname);
			rw_exit(&filemon->fm_mtx);
		}
	}
	return (ret);
}