mirror_zfs/module/os/linux/zfs/zfs_ioctl_os.c
Alan Somers 75b4cbf625
libzfs: On FreeBSD, use MNT_NOWAIT with getfsstat
`getfsstat(2)` is used to retrieve the list of mounted file systems,
which libzfs uses when fetching properties like mountpoint, atime,
setuid, etc.  The `mode` parameter may be `MNT_NOWAIT`, which uses
information in the VFS's cache, or `MNT_WAIT`, which effectively does a
`statfs` on every single mounted file system in order to fetch the most
up-to-date information.  As far as I can tell, the only fields that
libzfs cares about are the filesystem's name, mountpoint, fstypename,
and mount flags.  Those things are always updated on mount and unmount,
so they will always be accurate in the VFS's mount cache except in two
circumstances:

1) When a file system is busy unmounting
2) When a ZFS file system changes the value of a mount-overridable
   property like atime or setuid, but doesn't remount the file system.
   Right now that only happens when the property is changed by an
   unprivileged user who has delegated authority to change the property
   but not to mount the dataset.  But perhaps libzfs could choose to do
   it for other reasons in the future.

Switching to `MNT_NOWAIT` will greatly improve speed with no downside,
as long as we explicitly update the mount cache whenever we change a
mount-overridable property.

For comparison, Illumos gets this information using the native
`getmntany` and `getmntent` functions, which also use cached
information.  The illumos function that would refresh the cache,
`resetmnttab`, is never called by libzfs.

And on GNU/Linux, `getmntany` and `getmntent` don't even communicate
with the kernel directly.  They simply parse the file they are given,
which is usually /etc/mtab or /proc/mounts.  Perhaps the implementation
of /proc/mounts is synchronous, ala MNT_WAIT; I don't know.

Sponsored-by:	Axcient
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by:	Alan Somers <asomers@gmail.com>
Closes: #12091
2021-06-08 07:36:43 -06:00

281 lines
6.4 KiB
C

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Portions Copyright 2011 Martin Matuska
* Copyright 2015, OmniTI Computer Consulting, Inc. All rights reserved.
* Portions Copyright 2012 Pawel Jakub Dawidek <pawel@dawidek.net>
* Copyright (c) 2014, 2016 Joyent, Inc. All rights reserved.
* Copyright 2016 Nexenta Systems, Inc. All rights reserved.
* Copyright (c) 2014, Joyent, Inc. All rights reserved.
* Copyright (c) 2011, 2018 by Delphix. All rights reserved.
* Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
* Copyright (c) 2013 Steven Hartland. All rights reserved.
* Copyright (c) 2014 Integros [integros.com]
* Copyright 2016 Toomas Soome <tsoome@me.com>
* Copyright (c) 2016 Actifio, Inc. All rights reserved.
* Copyright (c) 2018, loli10K <ezomori.nozomu@gmail.com>. All rights reserved.
* Copyright 2017 RackTop Systems.
* Copyright (c) 2017 Open-E, Inc. All Rights Reserved.
* Copyright (c) 2019 Datto Inc.
*/
#include <sys/types.h>
#include <sys/param.h>
#include <sys/errno.h>
#include <sys/uio.h>
#include <sys/file.h>
#include <sys/kmem.h>
#include <sys/stat.h>
#include <sys/zfs_ioctl.h>
#include <sys/zfs_vfsops.h>
#include <sys/zap.h>
#include <sys/spa.h>
#include <sys/nvpair.h>
#include <sys/fs/zfs.h>
#include <sys/zfs_ctldir.h>
#include <sys/zfs_dir.h>
#include <sys/zfs_onexit.h>
#include <sys/zvol.h>
#include <sys/fm/util.h>
#include <sys/dsl_crypt.h>
#include <sys/zfs_ioctl_impl.h>
#include <sys/zfs_sysfs.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
boolean_t
zfs_vfs_held(zfsvfs_t *zfsvfs)
{
return (zfsvfs->z_sb != NULL);
}
int
zfs_vfs_ref(zfsvfs_t **zfvp)
{
if (*zfvp == NULL || (*zfvp)->z_sb == NULL ||
!atomic_inc_not_zero(&((*zfvp)->z_sb->s_active))) {
return (SET_ERROR(ESRCH));
}
return (0);
}
void
zfs_vfs_rele(zfsvfs_t *zfsvfs)
{
deactivate_super(zfsvfs->z_sb);
}
void
zfsdev_private_set_state(void *priv, zfsdev_state_t *zs)
{
struct file *filp = priv;
filp->private_data = zs;
}
zfsdev_state_t *
zfsdev_private_get_state(void *priv)
{
struct file *filp = priv;
return (filp->private_data);
}
static int
zfsdev_open(struct inode *ino, struct file *filp)
{
int error;
mutex_enter(&zfsdev_state_lock);
error = zfsdev_state_init(filp);
mutex_exit(&zfsdev_state_lock);
return (-error);
}
static int
zfsdev_release(struct inode *ino, struct file *filp)
{
zfsdev_state_destroy(filp);
return (0);
}
static long
zfsdev_ioctl(struct file *filp, unsigned cmd, unsigned long arg)
{
uint_t vecnum;
zfs_cmd_t *zc;
int error, rc;
vecnum = cmd - ZFS_IOC_FIRST;
zc = kmem_zalloc(sizeof (zfs_cmd_t), KM_SLEEP);
if (ddi_copyin((void *)(uintptr_t)arg, zc, sizeof (zfs_cmd_t), 0)) {
error = -SET_ERROR(EFAULT);
goto out;
}
error = -zfsdev_ioctl_common(vecnum, zc, 0);
rc = ddi_copyout(zc, (void *)(uintptr_t)arg, sizeof (zfs_cmd_t), 0);
if (error == 0 && rc != 0)
error = -SET_ERROR(EFAULT);
out:
kmem_free(zc, sizeof (zfs_cmd_t));
return (error);
}
uint64_t
zfs_max_nvlist_src_size_os(void)
{
if (zfs_max_nvlist_src_size != 0)
return (zfs_max_nvlist_src_size);
return (MIN(ptob(zfs_totalram_pages) / 4, 128 * 1024 * 1024));
}
/* Update the VFS's cache of mountpoint properties */
void
zfs_ioctl_update_mount_cache(const char *dsname)
{
}
void
zfs_ioctl_init_os(void)
{
}
#ifdef CONFIG_COMPAT
static long
zfsdev_compat_ioctl(struct file *filp, unsigned cmd, unsigned long arg)
{
return (zfsdev_ioctl(filp, cmd, arg));
}
#else
#define zfsdev_compat_ioctl NULL
#endif
static const struct file_operations zfsdev_fops = {
.open = zfsdev_open,
.release = zfsdev_release,
.unlocked_ioctl = zfsdev_ioctl,
.compat_ioctl = zfsdev_compat_ioctl,
.owner = THIS_MODULE,
};
static struct miscdevice zfs_misc = {
.minor = ZFS_DEVICE_MINOR,
.name = ZFS_DRIVER,
.fops = &zfsdev_fops,
};
MODULE_ALIAS_MISCDEV(ZFS_DEVICE_MINOR);
MODULE_ALIAS("devname:zfs");
int
zfsdev_attach(void)
{
int error;
error = misc_register(&zfs_misc);
if (error == -EBUSY) {
/*
* Fallback to dynamic minor allocation in the event of a
* collision with a reserved minor in linux/miscdevice.h.
* In this case the kernel modules must be manually loaded.
*/
printk(KERN_INFO "ZFS: misc_register() with static minor %d "
"failed %d, retrying with MISC_DYNAMIC_MINOR\n",
ZFS_DEVICE_MINOR, error);
zfs_misc.minor = MISC_DYNAMIC_MINOR;
error = misc_register(&zfs_misc);
}
if (error)
printk(KERN_INFO "ZFS: misc_register() failed %d\n", error);
return (error);
}
void
zfsdev_detach(void)
{
misc_deregister(&zfs_misc);
}
#ifdef ZFS_DEBUG
#define ZFS_DEBUG_STR " (DEBUG mode)"
#else
#define ZFS_DEBUG_STR ""
#endif
static int __init
openzfs_init(void)
{
int error;
if ((error = zfs_kmod_init()) != 0) {
printk(KERN_NOTICE "ZFS: Failed to Load ZFS Filesystem v%s-%s%s"
", rc = %d\n", ZFS_META_VERSION, ZFS_META_RELEASE,
ZFS_DEBUG_STR, error);
return (-error);
}
zfs_sysfs_init();
printk(KERN_NOTICE "ZFS: Loaded module v%s-%s%s, "
"ZFS pool version %s, ZFS filesystem version %s\n",
ZFS_META_VERSION, ZFS_META_RELEASE, ZFS_DEBUG_STR,
SPA_VERSION_STRING, ZPL_VERSION_STRING);
#ifndef CONFIG_FS_POSIX_ACL
printk(KERN_NOTICE "ZFS: Posix ACLs disabled by kernel\n");
#endif /* CONFIG_FS_POSIX_ACL */
return (0);
}
static void __exit
openzfs_fini(void)
{
zfs_sysfs_fini();
zfs_kmod_fini();
printk(KERN_NOTICE "ZFS: Unloaded module v%s-%s%s\n",
ZFS_META_VERSION, ZFS_META_RELEASE, ZFS_DEBUG_STR);
}
#if defined(_KERNEL)
module_init(openzfs_init);
module_exit(openzfs_fini);
#endif
ZFS_MODULE_DESCRIPTION("ZFS");
ZFS_MODULE_AUTHOR(ZFS_META_AUTHOR);
ZFS_MODULE_LICENSE(ZFS_META_LICENSE);
ZFS_MODULE_VERSION(ZFS_META_VERSION "-" ZFS_META_RELEASE);