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	Restructure the zfsdev_state_list to allow for lock-free reading by converting to a simple singly-linked list from which items are never deleted and over which only forward iterations are performed. It depends on, among other things, the atomicity of accessing the zs_minor integer and zs_next pointer. This fixes a lock inversion in which the zfsdev_state_lock is used by both the sync task (txg_sync) and indirectly by any user program which uses /dev/zfs; the zfsdev_release method uses the same lock and then blocks on the sync task. The most typical failure scenerio occurs when the sync task is cleaning up a user hold while various concurrent "zfs" commands are in progress. Neither Illumos nor Solaris are affected by this issue because they use DDI interface which provides lock-free reading of device state via the ddi_get_soft_state() function. Signed-off-by: Tim Chase <tim@chase2k.com> Signed-off-by: Chunwei Chen <tuxoko@gmail.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #2301
		
			
				
	
	
		
			400 lines
		
	
	
		
			10 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			400 lines
		
	
	
		
			10 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
/*
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 * CDDL HEADER START
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 *
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 * The contents of this file are subject to the terms of the
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 * Common Development and Distribution License (the "License").
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 * You may not use this file except in compliance with the License.
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 *
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 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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 * or http://www.opensolaris.org/os/licensing.
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 * See the License for the specific language governing permissions
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 * and limitations under the License.
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 *
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 * When distributing Covered Code, include this CDDL HEADER in each
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 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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 * If applicable, add the following below this CDDL HEADER, with the
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 * fields enclosed by brackets "[]" replaced with your own identifying
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 * information: Portions Copyright [yyyy] [name of copyright owner]
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 *
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 * CDDL HEADER END
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 */
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/*
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 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
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 * Copyright (c) 2012 by Delphix. All rights reserved.
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 */
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#ifndef	_SYS_ZFS_IOCTL_H
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#define	_SYS_ZFS_IOCTL_H
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#include <sys/cred.h>
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#include <sys/dmu.h>
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#include <sys/zio.h>
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#include <sys/dsl_deleg.h>
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#include <sys/spa.h>
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#include <sys/zfs_stat.h>
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#ifdef _KERNEL
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#include <sys/nvpair.h>
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#endif	/* _KERNEL */
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#ifdef	__cplusplus
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extern "C" {
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#endif
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/*
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 * The structures in this file are passed between userland and the
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 * kernel.  Userland may be running a 32-bit process, while the kernel
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 * is 64-bit.  Therefore, these structures need to compile the same in
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 * 32-bit and 64-bit.  This means not using type "long", and adding
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 * explicit padding so that the 32-bit structure will not be packed more
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 * tightly than the 64-bit structure (which requires 64-bit alignment).
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 */
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/*
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 * Property values for snapdir
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 */
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#define	ZFS_SNAPDIR_HIDDEN		0
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#define	ZFS_SNAPDIR_VISIBLE		1
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/*
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 * Property values for snapdev
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 */
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#define	ZFS_SNAPDEV_HIDDEN		0
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#define	ZFS_SNAPDEV_VISIBLE		1
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/*
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 * Property values for acltype
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 */
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#define	ZFS_ACLTYPE_OFF			0
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#define	ZFS_ACLTYPE_POSIXACL		1
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/*
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 * Field manipulation macros for the drr_versioninfo field of the
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 * send stream header.
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 */
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/*
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 * Header types for zfs send streams.
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 */
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typedef enum drr_headertype {
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	DMU_SUBSTREAM = 0x1,
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	DMU_COMPOUNDSTREAM = 0x2
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} drr_headertype_t;
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#define	DMU_GET_STREAM_HDRTYPE(vi)	BF64_GET((vi), 0, 2)
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#define	DMU_SET_STREAM_HDRTYPE(vi, x)	BF64_SET((vi), 0, 2, x)
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#define	DMU_GET_FEATUREFLAGS(vi)	BF64_GET((vi), 2, 30)
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#define	DMU_SET_FEATUREFLAGS(vi, x)	BF64_SET((vi), 2, 30, x)
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/*
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 * Feature flags for zfs send streams (flags in drr_versioninfo)
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 */
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#define	DMU_BACKUP_FEATURE_DEDUP	(0x1)
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#define	DMU_BACKUP_FEATURE_DEDUPPROPS	(0x2)
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#define	DMU_BACKUP_FEATURE_SA_SPILL	(0x4)
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/*
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 * Mask of all supported backup features
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 */
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#define	DMU_BACKUP_FEATURE_MASK	(DMU_BACKUP_FEATURE_DEDUP | \
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		DMU_BACKUP_FEATURE_DEDUPPROPS | DMU_BACKUP_FEATURE_SA_SPILL)
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/* Are all features in the given flag word currently supported? */
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#define	DMU_STREAM_SUPPORTED(x)	(!((x) & ~DMU_BACKUP_FEATURE_MASK))
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/*
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 * The drr_versioninfo field of the dmu_replay_record has the
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 * following layout:
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 *
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 *	64	56	48	40	32	24	16	8	0
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 *	+-------+-------+-------+-------+-------+-------+-------+-------+
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 *  	|		reserved	|        feature-flags	    |C|S|
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 *	+-------+-------+-------+-------+-------+-------+-------+-------+
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 *
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 * The low order two bits indicate the header type: SUBSTREAM (0x1)
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 * or COMPOUNDSTREAM (0x2).  Using two bits for this is historical:
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 * this field used to be a version number, where the two version types
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 * were 1 and 2.  Using two bits for this allows earlier versions of
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 * the code to be able to recognize send streams that don't use any
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 * of the features indicated by feature flags.
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 */
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#define	DMU_BACKUP_MAGIC 0x2F5bacbacULL
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#define	DRR_FLAG_CLONE		(1<<0)
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#define	DRR_FLAG_CI_DATA	(1<<1)
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/*
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 * flags in the drr_checksumflags field in the DRR_WRITE and
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 * DRR_WRITE_BYREF blocks
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 */
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#define	DRR_CHECKSUM_DEDUP	(1<<0)
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#define	DRR_IS_DEDUP_CAPABLE(flags)	((flags) & DRR_CHECKSUM_DEDUP)
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/*
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 * zfs ioctl command structure
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 */
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typedef struct dmu_replay_record {
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	enum {
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		DRR_BEGIN, DRR_OBJECT, DRR_FREEOBJECTS,
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		DRR_WRITE, DRR_FREE, DRR_END, DRR_WRITE_BYREF,
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		DRR_SPILL, DRR_NUMTYPES
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	} drr_type;
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	uint32_t drr_payloadlen;
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	union {
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		struct drr_begin {
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			uint64_t drr_magic;
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			uint64_t drr_versioninfo; /* was drr_version */
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			uint64_t drr_creation_time;
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			dmu_objset_type_t drr_type;
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			uint32_t drr_flags;
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			uint64_t drr_toguid;
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			uint64_t drr_fromguid;
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			char drr_toname[MAXNAMELEN];
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		} drr_begin;
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		struct drr_end {
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			zio_cksum_t drr_checksum;
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			uint64_t drr_toguid;
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		} drr_end;
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		struct drr_object {
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			uint64_t drr_object;
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			dmu_object_type_t drr_type;
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			dmu_object_type_t drr_bonustype;
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			uint32_t drr_blksz;
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			uint32_t drr_bonuslen;
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			uint8_t drr_checksumtype;
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			uint8_t drr_compress;
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			uint8_t drr_pad[6];
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			uint64_t drr_toguid;
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			/* bonus content follows */
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		} drr_object;
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		struct drr_freeobjects {
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			uint64_t drr_firstobj;
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			uint64_t drr_numobjs;
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			uint64_t drr_toguid;
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		} drr_freeobjects;
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		struct drr_write {
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			uint64_t drr_object;
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			dmu_object_type_t drr_type;
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			uint32_t drr_pad;
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			uint64_t drr_offset;
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			uint64_t drr_length;
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			uint64_t drr_toguid;
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			uint8_t drr_checksumtype;
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			uint8_t drr_checksumflags;
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			uint8_t drr_pad2[6];
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			ddt_key_t drr_key; /* deduplication key */
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			/* content follows */
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		} drr_write;
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		struct drr_free {
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			uint64_t drr_object;
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			uint64_t drr_offset;
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			uint64_t drr_length;
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			uint64_t drr_toguid;
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		} drr_free;
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		struct drr_write_byref {
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			/* where to put the data */
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			uint64_t drr_object;
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			uint64_t drr_offset;
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			uint64_t drr_length;
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			uint64_t drr_toguid;
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			/* where to find the prior copy of the data */
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			uint64_t drr_refguid;
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			uint64_t drr_refobject;
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			uint64_t drr_refoffset;
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			/* properties of the data */
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			uint8_t drr_checksumtype;
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			uint8_t drr_checksumflags;
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			uint8_t drr_pad2[6];
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			ddt_key_t drr_key; /* deduplication key */
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		} drr_write_byref;
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		struct drr_spill {
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			uint64_t drr_object;
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			uint64_t drr_length;
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			uint64_t drr_toguid;
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			uint64_t drr_pad[4]; /* needed for crypto */
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			/* spill data follows */
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		} drr_spill;
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	} drr_u;
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} dmu_replay_record_t;
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/* diff record range types */
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typedef enum diff_type {
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	DDR_NONE = 0x1,
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	DDR_INUSE = 0x2,
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	DDR_FREE = 0x4
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} diff_type_t;
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/*
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 * The diff reports back ranges of free or in-use objects.
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 */
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typedef struct dmu_diff_record {
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	uint64_t ddr_type;
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	uint64_t ddr_first;
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	uint64_t ddr_last;
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} dmu_diff_record_t;
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typedef struct zinject_record {
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	uint64_t	zi_objset;
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	uint64_t	zi_object;
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	uint64_t	zi_start;
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	uint64_t	zi_end;
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	uint64_t	zi_guid;
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	uint32_t	zi_level;
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	uint32_t	zi_error;
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	uint64_t	zi_type;
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	uint32_t	zi_freq;
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	uint32_t	zi_failfast;
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	char		zi_func[MAXNAMELEN];
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	uint32_t	zi_iotype;
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	int32_t		zi_duration;
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	uint64_t	zi_timer;
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	uint32_t	zi_cmd;
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	uint32_t	zi_pad;
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} zinject_record_t;
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#define	ZINJECT_NULL		0x1
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#define	ZINJECT_FLUSH_ARC	0x2
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#define	ZINJECT_UNLOAD_SPA	0x4
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#define	ZEVENT_NONE		0x0
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#define	ZEVENT_NONBLOCK		0x1
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#define	ZEVENT_SIZE		1024
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#define	ZEVENT_SEEK_START	0
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#define	ZEVENT_SEEK_END		UINT64_MAX
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typedef enum zinject_type {
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	ZINJECT_UNINITIALIZED,
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	ZINJECT_DATA_FAULT,
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	ZINJECT_DEVICE_FAULT,
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	ZINJECT_LABEL_FAULT,
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	ZINJECT_IGNORED_WRITES,
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	ZINJECT_PANIC,
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	ZINJECT_DELAY_IO,
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} zinject_type_t;
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typedef struct zfs_share {
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	uint64_t	z_exportdata;
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	uint64_t	z_sharedata;
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	uint64_t	z_sharetype;	/* 0 = share, 1 = unshare */
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	uint64_t	z_sharemax;  /* max length of share string */
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} zfs_share_t;
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/*
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 * ZFS file systems may behave the usual, POSIX-compliant way, where
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 * name lookups are case-sensitive.  They may also be set up so that
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 * all the name lookups are case-insensitive, or so that only some
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 * lookups, the ones that set an FIGNORECASE flag, are case-insensitive.
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 */
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typedef enum zfs_case {
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	ZFS_CASE_SENSITIVE,
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	ZFS_CASE_INSENSITIVE,
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	ZFS_CASE_MIXED
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} zfs_case_t;
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typedef struct zfs_cmd {
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	char		zc_name[MAXPATHLEN];	/* name of pool or dataset */
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	uint64_t	zc_nvlist_src;		/* really (char *) */
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	uint64_t	zc_nvlist_src_size;
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	uint64_t	zc_nvlist_dst;		/* really (char *) */
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	uint64_t	zc_nvlist_dst_size;
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	boolean_t	zc_nvlist_dst_filled;	/* put an nvlist in dst? */
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	int		zc_pad2;
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	/*
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	 * The following members are for legacy ioctls which haven't been
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	 * converted to the new method.
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	 */
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	uint64_t	zc_history;		/* really (char *) */
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	char		zc_value[MAXPATHLEN * 2];
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	char		zc_string[MAXNAMELEN];
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	uint64_t	zc_guid;
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	uint64_t	zc_nvlist_conf;		/* really (char *) */
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	uint64_t	zc_nvlist_conf_size;
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	uint64_t	zc_cookie;
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	uint64_t	zc_objset_type;
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	uint64_t	zc_perm_action;
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	uint64_t	zc_history_len;
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	uint64_t	zc_history_offset;
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	uint64_t	zc_obj;
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	uint64_t	zc_iflags;		/* internal to zfs(7fs) */
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	zfs_share_t	zc_share;
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	dmu_objset_stats_t zc_objset_stats;
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	struct drr_begin zc_begin_record;
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	zinject_record_t zc_inject_record;
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	boolean_t	zc_defer_destroy;
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	boolean_t	zc_temphold;
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	uint64_t	zc_action_handle;
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	int		zc_cleanup_fd;
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	uint8_t		zc_simple;
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	uint8_t		zc_pad[3];		/* alignment */
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	uint64_t	zc_sendobj;
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	uint64_t	zc_fromobj;
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	uint64_t	zc_createtxg;
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	zfs_stat_t	zc_stat;
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} zfs_cmd_t;
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typedef struct zfs_useracct {
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	char zu_domain[256];
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	uid_t zu_rid;
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	uint32_t zu_pad;
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	uint64_t zu_space;
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} zfs_useracct_t;
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#define	ZFSDEV_MAX_MINOR	(1 << 16)
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#define	ZFS_MIN_MINOR	(ZFSDEV_MAX_MINOR + 1)
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#define	ZPOOL_EXPORT_AFTER_SPLIT 0x1
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#ifdef _KERNEL
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typedef struct zfs_creat {
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	nvlist_t	*zct_zplprops;
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	nvlist_t	*zct_props;
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} zfs_creat_t;
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extern int zfs_secpolicy_snapshot_perms(const char *name, cred_t *cr);
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extern int zfs_secpolicy_rename_perms(const char *from,
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    const char *to, cred_t *cr);
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extern int zfs_secpolicy_destroy_perms(const char *name, cred_t *cr);
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extern int zfs_unmount_snap(const char *);
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extern void zfs_destroy_unmount_origin(const char *);
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extern boolean_t dataset_name_hidden(const char *name);
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enum zfsdev_state_type {
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	ZST_ONEXIT,
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	ZST_ZEVENT,
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	ZST_ALL,
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};
 | 
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 | 
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/*
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						|
 * The zfsdev_state_t structure is managed as a singly-linked list
 | 
						|
 * from which items are never deleted.  This allows for lock-free
 | 
						|
 * reading of the list so long as assignments to the zs_next and
 | 
						|
 * reads from zs_minor are performed atomically.  Empty items are
 | 
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 * indicated by storing -1 into zs_minor.
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 */
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typedef struct zfsdev_state {
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	struct zfsdev_state	*zs_next;	/* next zfsdev_state_t link */
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	struct file		*zs_file;	/* associated file struct */
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						|
	minor_t			zs_minor;	/* made up minor number */
 | 
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	void			*zs_onexit;	/* onexit data */
 | 
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	void			*zs_zevent;	/* zevent data */
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} zfsdev_state_t;
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extern void *zfsdev_get_state(minor_t minor, enum zfsdev_state_type which);
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extern minor_t zfsdev_getminor(struct file *filp);
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extern minor_t zfsdev_minor_alloc(void);
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#endif	/* _KERNEL */
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#ifdef	__cplusplus
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}
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#endif
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#endif	/* _SYS_ZFS_IOCTL_H */
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