xref: /illumos-gate/usr/src/uts/common/fs/zfs/zvol.c (revision 7b421453)

/*
 * 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 2010 Robert Milkowski
 *
 * Copyright 2017 Nexenta Systems, Inc.  All rights reserved.
 * Copyright (c) 2012, 2020 by Delphix. All rights reserved.
 * Copyright (c) 2014 Integros [integros.com]
 * Copyright 2019 Joyent, Inc.
 */

/*
 * ZFS volume emulation driver.
 *
 * Makes a DMU object look like a volume of arbitrary size, up to 2^64 bytes.
 * Volumes are accessed through the symbolic links named:
 *
 * /dev/zvol/dsk/<pool_name>/<dataset_name>
 * /dev/zvol/rdsk/<pool_name>/<dataset_name>
 *
 * These links are created by the /dev filesystem (sdev_zvolops.c).
 * Volumes are persistent through reboot.  No user command needs to be
 * run before opening and using a device.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/errno.h>
#include <sys/uio.h>
#include <sys/buf.h>
#include <sys/modctl.h>
#include <sys/open.h>
#include <sys/kmem.h>
#include <sys/conf.h>
#include <sys/cmn_err.h>
#include <sys/stat.h>
#include <sys/zap.h>
#include <sys/spa.h>
#include <sys/spa_impl.h>
#include <sys/zio.h>
#include <sys/dmu_traverse.h>
#include <sys/dnode.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_prop.h>
#include <sys/dkio.h>
#include <sys/efi_partition.h>
#include <sys/byteorder.h>
#include <sys/pathname.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#include <sys/crc32.h>
#include <sys/dirent.h>
#include <sys/policy.h>
#include <sys/fs/zfs.h>
#include <sys/zfs_ioctl.h>
#include <sys/mkdev.h>
#include <sys/zil.h>
#include <sys/refcount.h>
#include <sys/zfs_znode.h>
#include <sys/zfs_rlock.h>
#include <sys/vdev_impl.h>
#include <sys/zvol.h>
#include <sys/dumphdr.h>
#include <sys/zil_impl.h>
#include <sys/dbuf.h>
#include <sys/dmu_tx.h>
#include <sys/zfeature.h>
#include <sys/zio_checksum.h>
#include <sys/zil_impl.h>
#include <sys/smt.h>
#include <sys/dkioc_free_util.h>
#include <sys/zfs_rlock.h>

#include "zfs_namecheck.h"

void *zfsdev_state;
static char *zvol_tag = "zvol_tag";

#define	ZVOL_DUMPSIZE		"dumpsize"

/*
 * This lock protects the zfsdev_state structure from being modified
 * while it's being used, e.g. an open that comes in before a create
 * finishes.  It also protects temporary opens of the dataset so that,
 * e.g., an open doesn't get a spurious EBUSY.
 */
kmutex_t zfsdev_state_lock;
static uint32_t zvol_minors;

typedef struct zvol_extent {
	list_node_t	ze_node;
	dva_t		ze_dva;		/* dva associated with this extent */
	uint64_t	ze_nblks;	/* number of blocks in extent */
} zvol_extent_t;

/*
 * The in-core state of each volume.
 */
typedef struct zvol_state {
	char		zv_name[MAXPATHLEN]; /* pool/dd name */
	uint64_t	zv_volsize;	/* amount of space we advertise */
	uint64_t	zv_volblocksize; /* volume block size */
	minor_t		zv_minor;	/* minor number */
	uint8_t		zv_min_bs;	/* minimum addressable block shift */
	uint8_t		zv_flags;	/* readonly, dumpified, etc. */
	objset_t	*zv_objset;	/* objset handle */
	uint32_t	zv_open_count[OTYPCNT];	/* open counts */
	uint32_t	zv_total_opens;	/* total open count */
	zilog_t		*zv_zilog;	/* ZIL handle */
	list_t		zv_extents;	/* List of extents for dump */
	rangelock_t	zv_rangelock;
	dnode_t		*zv_dn;		/* dnode hold */
} zvol_state_t;

/*
 * zvol specific flags
 */
#define	ZVOL_RDONLY	0x1
#define	ZVOL_DUMPIFIED	0x2
#define	ZVOL_EXCL	0x4
#define	ZVOL_WCE	0x8

/*
 * zvol maximum transfer in one DMU tx.
 */
int zvol_maxphys = DMU_MAX_ACCESS/2;

/*
 * Toggle unmap functionality.
 */
boolean_t zvol_unmap_enabled = B_TRUE;

/*
 * If true, unmaps requested as synchronous are executed synchronously,
 * otherwise all unmaps are asynchronous.
 */
boolean_t zvol_unmap_sync_enabled = B_FALSE;

extern int zfs_set_prop_nvlist(const char *, zprop_source_t,
    nvlist_t *, nvlist_t *);
static int zvol_remove_zv(zvol_state_t *);
static int zvol_get_data(void *arg, lr_write_t *lr, char *buf,
    struct lwb *lwb, zio_t *zio);
static int zvol_dumpify(zvol_state_t *zv);
static int zvol_dump_fini(zvol_state_t *zv);
static int zvol_dump_init(zvol_state_t *zv, boolean_t resize);

static void
zvol_size_changed(zvol_state_t *zv, uint64_t volsize)
{
	dev_t dev = makedevice(ddi_driver_major(zfs_dip), zv->zv_minor);

	zv->zv_volsize = volsize;
	VERIFY(ddi_prop_update_int64(dev, zfs_dip,
	    "Size", volsize) == DDI_SUCCESS);
	VERIFY(ddi_prop_update_int64(dev, zfs_dip,
	    "Nblocks", lbtodb(volsize)) == DDI_SUCCESS);

	/* Notify specfs to invalidate the cached size */
	spec_size_invalidate(dev, VBLK);
	spec_size_invalidate(dev, VCHR);
}

int
zvol_check_volsize(uint64_t volsize, uint64_t blocksize)
{
	if (volsize == 0)
		return (SET_ERROR(EINVAL));

	if (volsize % blocksize != 0)
		return (SET_ERROR(EINVAL));

#ifdef _ILP32
	if (volsize - 1 > SPEC_MAXOFFSET_T)
		return (SET_ERROR(EOVERFLOW));
#endif
	return (0);
}

int
zvol_check_volblocksize(uint64_t volblocksize)
{
	if (volblocksize < SPA_MINBLOCKSIZE ||
	    volblocksize > SPA_OLD_MAXBLOCKSIZE ||
	    !ISP2(volblocksize))
		return (SET_ERROR(EDOM));

	return (0);
}

int
zvol_get_stats(objset_t *os, nvlist_t *nv)
{
	int error;
	dmu_object_info_t doi;
	uint64_t val;

	error = zap_lookup(os, ZVOL_ZAP_OBJ, "size", 8, 1, &val);
	if (error)
		return (error);

	dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_VOLSIZE, val);

	error = dmu_object_info(os, ZVOL_OBJ, &doi);

	if (error == 0) {
		dsl_prop_nvlist_add_uint64(nv, ZFS_PROP_VOLBLOCKSIZE,
		    doi.doi_data_block_size);
	}

	return (error);
}

static zvol_state_t *
zvol_minor_lookup(const char *name)
{
	minor_t minor;
	zvol_state_t *zv;

	ASSERT(MUTEX_HELD(&zfsdev_state_lock));

	for (minor = 1; minor <= ZFSDEV_MAX_MINOR; minor++) {
		zv = zfsdev_get_soft_state(minor, ZSST_ZVOL);
		if (zv == NULL)
			continue;
		if (strcmp(zv->zv_name, name) == 0)
			return (zv);
	}

	return (NULL);
}

/* extent mapping arg */
struct maparg {
	zvol_state_t	*ma_zv;
	uint64_t	ma_blks;
};

/*ARGSUSED*/
static int
zvol_map_block(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
    const zbookmark_phys_t *zb, const dnode_phys_t *dnp, void *arg)
{
	struct maparg *ma = arg;
	zvol_extent_t *ze;
	int bs = ma->ma_zv->zv_volblocksize;

	if (bp == NULL || BP_IS_HOLE(bp) ||
	    zb->zb_object != ZVOL_OBJ || zb->zb_level != 0)
		return (0);

	VERIFY(!BP_IS_EMBEDDED(bp));

	VERIFY3U(ma->ma_blks, ==, zb->zb_blkid);
	ma->ma_blks++;

	/* Abort immediately if we have encountered gang blocks */
	if (BP_IS_GANG(bp))
		return (SET_ERROR(EFRAGS));

	/*
	 * See if the block is at the end of the previous extent.
	 */
	ze = list_tail(&ma->ma_zv->zv_extents);
	if (ze &&
	    DVA_GET_VDEV(BP_IDENTITY(bp)) == DVA_GET_VDEV(&ze->ze_dva) &&
	    DVA_GET_OFFSET(BP_IDENTITY(bp)) ==
	    DVA_GET_OFFSET(&ze->ze_dva) + ze->ze_nblks * bs) {
		ze->ze_nblks++;
		return (0);
	}

	dprintf_bp(bp, "%s", "next blkptr:");

	/* start a new extent */
	ze = kmem_zalloc(sizeof (zvol_extent_t), KM_SLEEP);
	ze->ze_dva = bp->blk_dva[0];	/* structure assignment */
	ze->ze_nblks = 1;
	list_insert_tail(&ma->ma_zv->zv_extents, ze);
	return (0);
}

static void
zvol_free_extents(zvol_state_t *zv)
{
	zvol_extent_t *ze;

	while (ze = list_head(&zv->zv_extents)) {
		list_remove(&zv->zv_extents, ze);
		kmem_free(ze, sizeof (zvol_extent_t));
	}
}

static int
zvol_get_lbas(zvol_state_t *zv)
{
	objset_t *os = zv->zv_objset;
	struct maparg	ma;
	int		err;

	ma.ma_zv = zv;
	ma.ma_blks = 0;
	zvol_free_extents(zv);

	/* commit any in-flight changes before traversing the dataset */
	txg_wait_synced(dmu_objset_pool(os), 0);
	err = traverse_dataset(dmu_objset_ds(os), 0,
	    TRAVERSE_PRE | TRAVERSE_PREFETCH_METADATA, zvol_map_block, &ma);
	if (err || ma.ma_blks != (zv->zv_volsize / zv->zv_volblocksize)) {
		zvol_free_extents(zv);
		return (err ? err : EIO);
	}

	return (0);
}

/* ARGSUSED */
void
zvol_create_cb(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx)
{
	zfs_creat_t *zct = arg;
	nvlist_t *nvprops = zct->zct_props;
	int error;
	uint64_t volblocksize, volsize;

	VERIFY(nvlist_lookup_uint64(nvprops,
	    zfs_prop_to_name(ZFS_PROP_VOLSIZE), &volsize) == 0);
	if (nvlist_lookup_uint64(nvprops,
	    zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), &volblocksize) != 0)
		volblocksize = zfs_prop_default_numeric(ZFS_PROP_VOLBLOCKSIZE);

	/*
	 * These properties must be removed from the list so the generic
	 * property setting step won't apply to them.
	 */
	VERIFY(nvlist_remove_all(nvprops,
	    zfs_prop_to_name(ZFS_PROP_VOLSIZE)) == 0);
	(void) nvlist_remove_all(nvprops,
	    zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE));

	error = dmu_object_claim(os, ZVOL_OBJ, DMU_OT_ZVOL, volblocksize,
	    DMU_OT_NONE, 0, tx);
	ASSERT(error == 0);

	error = zap_create_claim(os, ZVOL_ZAP_OBJ, DMU_OT_ZVOL_PROP,
	    DMU_OT_NONE, 0, tx);
	ASSERT(error == 0);

	error = zap_update(os, ZVOL_ZAP_OBJ, "size", 8, 1, &volsize, tx);
	ASSERT(error == 0);
}

/*
 * Replay a TX_TRUNCATE ZIL transaction if asked.  TX_TRUNCATE is how we
 * implement DKIOCFREE/free-long-range.
 */
static int
zvol_replay_truncate(void *arg1, void *arg2, boolean_t byteswap)
{
	zvol_state_t *zv = arg1;
	lr_truncate_t *lr = arg2;
	uint64_t offset, length;

	if (byteswap)
		byteswap_uint64_array(lr, sizeof (*lr));

	offset = lr->lr_offset;
	length = lr->lr_length;

	return (dmu_free_long_range(zv->zv_objset, ZVOL_OBJ, offset, length));
}

/*
 * Replay a TX_WRITE ZIL transaction that didn't get committed
 * after a system failure
 */
/* ARGSUSED */
static int
zvol_replay_write(void *arg1, void *arg2, boolean_t byteswap)
{
	zvol_state_t *zv = arg1;
	lr_write_t *lr = arg2;
	objset_t *os = zv->zv_objset;
	char *data = (char *)(lr + 1);	/* data follows lr_write_t */
	uint64_t offset, length;
	dmu_tx_t *tx;
	int error;

	if (byteswap)
		byteswap_uint64_array(lr, sizeof (*lr));

	offset = lr->lr_offset;
	length = lr->lr_length;

	/* If it's a dmu_sync() block, write the whole block */
	if (lr->lr_common.lrc_reclen == sizeof (lr_write_t)) {
		uint64_t blocksize = BP_GET_LSIZE(&lr->lr_blkptr);
		if (length < blocksize) {
			offset -= offset % blocksize;
			length = blocksize;
		}
	}

	tx = dmu_tx_create(os);
	dmu_tx_hold_write(tx, ZVOL_OBJ, offset, length);
	error = dmu_tx_assign(tx, TXG_WAIT);
	if (error) {
		dmu_tx_abort(tx);
	} else {
		dmu_write(os, ZVOL_OBJ, offset, length, data, tx);
		dmu_tx_commit(tx);
	}

	return (error);
}

/* ARGSUSED */
static int
zvol_replay_err(void *arg1, void *arg2, boolean_t byteswap)
{
	return (SET_ERROR(ENOTSUP));
}

/*
 * Callback vectors for replaying records.
 * Only TX_WRITE and TX_TRUNCATE are needed for zvol.
 */
zil_replay_func_t *zvol_replay_vector[TX_MAX_TYPE] = {
	zvol_replay_err,	/* 0 no such transaction type */
	zvol_replay_err,	/* TX_CREATE */
	zvol_replay_err,	/* TX_MKDIR */
	zvol_replay_err,	/* TX_MKXATTR */
	zvol_replay_err,	/* TX_SYMLINK */
	zvol_replay_err,	/* TX_REMOVE */
	zvol_replay_err,	/* TX_RMDIR */
	zvol_replay_err,	/* TX_LINK */
	zvol_replay_err,	/* TX_RENAME */
	zvol_replay_write,	/* TX_WRITE */
	zvol_replay_truncate,	/* TX_TRUNCATE */
	zvol_replay_err,	/* TX_SETATTR */
	zvol_replay_err,	/* TX_ACL */
	zvol_replay_err,	/* TX_CREATE_ACL */
	zvol_replay_err,	/* TX_CREATE_ATTR */
	zvol_replay_err,	/* TX_CREATE_ACL_ATTR */
	zvol_replay_err,	/* TX_MKDIR_ACL */
	zvol_replay_err,	/* TX_MKDIR_ATTR */
	zvol_replay_err,	/* TX_MKDIR_ACL_ATTR */
	zvol_replay_err,	/* TX_WRITE2 */
};

int
zvol_name2minor(const char *name, minor_t *minor)
{
	zvol_state_t *zv;

	mutex_enter(&zfsdev_state_lock);
	zv = zvol_minor_lookup(name);
	if (minor && zv)
		*minor = zv->zv_minor;
	mutex_exit(&zfsdev_state_lock);
	return (zv ? 0 : -1);
}

/*
 * Create a minor node (plus a whole lot more) for the specified volume.
 */
int
zvol_create_minor(const char *name)
{
	zfs_soft_state_t *zs;
	zvol_state_t *zv;
	objset_t *os;
	dmu_object_info_t doi;
	minor_t minor = 0;
	char chrbuf[30], blkbuf[30];
	int error;

	mutex_enter(&zfsdev_state_lock);

	if (zvol_minor_lookup(name) != NULL) {
		mutex_exit(&zfsdev_state_lock);
		return (SET_ERROR(EEXIST));
	}

	/* lie and say we're read-only */
	error = dmu_objset_own(name, DMU_OST_ZVOL, B_TRUE, B_TRUE, FTAG, &os);

	if (error) {
		mutex_exit(&zfsdev_state_lock);
		return (error);
	}

	if ((minor = zfsdev_minor_alloc()) == 0) {
		dmu_objset_disown(os, 1, FTAG);
		mutex_exit(&zfsdev_state_lock);
		return (SET_ERROR(ENXIO));
	}

	if (ddi_soft_state_zalloc(zfsdev_state, minor) != DDI_SUCCESS) {
		dmu_objset_disown(os, 1, FTAG);
		mutex_exit(&zfsdev_state_lock);
		return (SET_ERROR(EAGAIN));
	}
	(void) ddi_prop_update_string(minor, zfs_dip, ZVOL_PROP_NAME,
	    (char *)name);

	(void) snprintf(chrbuf, sizeof (chrbuf), "%u,raw", minor);

	if (ddi_create_minor_node(zfs_dip, chrbuf, S_IFCHR,
	    minor, DDI_PSEUDO, 0) == DDI_FAILURE) {
		ddi_soft_state_free(zfsdev_state, minor);
		dmu_objset_disown(os, 1, FTAG);
		mutex_exit(&zfsdev_state_lock);
		return (SET_ERROR(EAGAIN));
	}

	(void) snprintf(blkbuf, sizeof (blkbuf), "%u", minor);

	if (ddi_create_minor_node(zfs_dip, blkbuf, S_IFBLK,
	    minor, DDI_PSEUDO, 0) == DDI_FAILURE) {
		ddi_remove_minor_node(zfs_dip, chrbuf);
		ddi_soft_state_free(zfsdev_state, minor);
		dmu_objset_disown(os, 1, FTAG);
		mutex_exit(&zfsdev_state_lock);
		return (SET_ERROR(EAGAIN));
	}

	zs = ddi_get_soft_state(zfsdev_state, minor);
	zs->zss_type = ZSST_ZVOL;
	zv = zs->zss_data = kmem_zalloc(sizeof (zvol_state_t), KM_SLEEP);
	(void) strlcpy(zv->zv_name, name, MAXPATHLEN);
	zv->zv_min_bs = DEV_BSHIFT;
	zv->zv_minor = minor;
	zv->zv_objset = os;
	if (dmu_objset_is_snapshot(os) || !spa_writeable(dmu_objset_spa(os)))
		zv->zv_flags |= ZVOL_RDONLY;
	rangelock_init(&zv->zv_rangelock, NULL, NULL);
	list_create(&zv->zv_extents, sizeof (zvol_extent_t),
	    offsetof(zvol_extent_t, ze_node));
	/* get and cache the blocksize */
	error = dmu_object_info(os, ZVOL_OBJ, &doi);
	ASSERT(error == 0);
	zv->zv_volblocksize = doi.doi_data_block_size;

	if (spa_writeable(dmu_objset_spa(os))) {
		if (zil_replay_disable)
			zil_destroy(dmu_objset_zil(os), B_FALSE);
		else
			zil_replay(os, zv, zvol_replay_vector);
	}
	dmu_objset_disown(os, 1, FTAG);
	zv->zv_objset = NULL;

	zvol_minors++;

	mutex_exit(&zfsdev_state_lock);

	return (0);
}

/*
 * Remove minor node for the specified volume.
 */
static int
zvol_remove_zv(zvol_state_t *zv)
{
	char nmbuf[20];
	minor_t minor = zv->zv_minor;

	ASSERT(MUTEX_HELD(&zfsdev_state_lock));
	if (zv->zv_total_opens != 0)
		return (SET_ERROR(EBUSY));

	(void) snprintf(nmbuf, sizeof (nmbuf), "%u,raw", minor);
	ddi_remove_minor_node(zfs_dip, nmbuf);

	(void) snprintf(nmbuf, sizeof (nmbuf), "%u", minor);
	ddi_remove_minor_node(zfs_dip, nmbuf);

	rangelock_fini(&zv->zv_rangelock);

	kmem_free(zv, sizeof (zvol_state_t));

	ddi_soft_state_free(zfsdev_state, minor);