xref: /illumos-gate/usr/src/uts/common/fs/zfs/sys/mmp.h (revision 4348eb901228d2f8fa50bb132a34248e8662074e)
1 /*
2  * CDDL HEADER START
3  *
4  * This file and its contents are supplied under the terms of the
5  * Common Development and Distribution License ("CDDL"), version 1.0.
6  * You may only use this file in accordance with the terms of version
7  * 1.0 of the CDDL.
8  *
9  * A full copy of the text of the CDDL should have accompanied this
10  * source.  A copy of the CDDL is also available via the Internet at
11  * http://www.illumos.org/license/CDDL.
12  *
13  * CDDL HEADER END
14  */
15 /*
16  * Copyright (C) 2017 by Lawrence Livermore National Security, LLC.
17  */
18 
19 #ifndef _SYS_MMP_H
20 #define	_SYS_MMP_H
21 
22 #include <sys/spa.h>
23 #include <sys/zfs_context.h>
24 #include <sys/uberblock_impl.h>
25 
26 #ifdef	__cplusplus
27 extern "C" {
28 #endif
29 
30 #define	MMP_MIN_INTERVAL		100	/* ms */
31 #define	MMP_DEFAULT_INTERVAL		1000	/* ms */
32 #define	MMP_DEFAULT_IMPORT_INTERVALS	20
33 #define	MMP_DEFAULT_FAIL_INTERVALS	10
34 #define	MMP_MIN_FAIL_INTERVALS		2	/* min if != 0 */
35 #define	MMP_IMPORT_SAFETY_FACTOR	200	/* pct */
36 #define	MMP_INTERVAL_OK(interval)	MAX(interval, MMP_MIN_INTERVAL)
37 #define	MMP_FAIL_INTVS_OK(fails)	(fails == 0 ? 0 : MAX(fails, \
38 					    MMP_MIN_FAIL_INTERVALS))
39 
40 typedef struct mmp_thread {
41 	kmutex_t	mmp_thread_lock; /* protect thread mgmt fields */
42 	kcondvar_t	mmp_thread_cv;
43 	kthread_t	*mmp_thread;
44 	uint8_t		mmp_thread_exiting;
45 	kmutex_t	mmp_io_lock;	/* protect below */
46 	hrtime_t	mmp_last_write;	/* last successful MMP write */
47 	uint64_t	mmp_delay;	/* decaying avg ns between MMP writes */
48 	uberblock_t	mmp_ub;		/* last ub written by sync */
49 	zio_t		*mmp_zio_root;	/* root of mmp write zios */
50 	uint64_t	mmp_kstat_id;	/* unique id for next MMP write kstat */
51 	int		mmp_skip_error; /* reason for last skipped write */
52 	vdev_t		*mmp_last_leaf;	/* last mmp write sent here */
53 	uint64_t	mmp_leaf_last_gen;	/* last mmp write sent here */
54 	uint32_t	mmp_seq;	/* intra-second update counter */
55 } mmp_thread_t;
56 
57 
58 extern void mmp_init(struct spa *spa);
59 extern void mmp_fini(struct spa *spa);
60 extern void mmp_thread_start(struct spa *spa);
61 extern void mmp_thread_stop(struct spa *spa);
62 extern void mmp_update_uberblock(struct spa *spa, struct uberblock *ub);
63 extern void mmp_signal_all_threads(void);
64 
65 /* Global tuning */
66 extern ulong_t zfs_multihost_interval;
67 extern uint_t zfs_multihost_fail_intervals;
68 extern uint_t zfs_multihost_import_intervals;
69 
70 #ifdef	__cplusplus
71 }
72 #endif
73 
74 #endif	/* _SYS_MMP_H */
75