1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _RAID1_H
3#define _RAID1_H
4
5/*
6 * each barrier unit size is 64MB fow now
7 * note: it must be larger than RESYNC_DEPTH
8 */
9#define BARRIER_UNIT_SECTOR_BITS	17
10#define BARRIER_UNIT_SECTOR_SIZE	(1<<17)
11/*
12 * In struct r1conf, the following members are related to I/O barrier
13 * buckets,
14 *	atomic_t	*nr_pending;
15 *	atomic_t	*nr_waiting;
16 *	atomic_t	*nr_queued;
17 *	atomic_t	*barrier;
18 * Each of them points to array of atomic_t variables, each array is
19 * designed to have BARRIER_BUCKETS_NR elements and occupy a single
20 * memory page. The data width of atomic_t variables is 4 bytes, equal
21 * to 1<<(ilog2(sizeof(atomic_t))), BARRIER_BUCKETS_NR_BITS is defined
22 * as (PAGE_SHIFT - ilog2(sizeof(int))) to make sure an array of
23 * atomic_t variables with BARRIER_BUCKETS_NR elements just exactly
24 * occupies a single memory page.
25 */
26#define BARRIER_BUCKETS_NR_BITS		(PAGE_SHIFT - ilog2(sizeof(atomic_t)))
27#define BARRIER_BUCKETS_NR		(1<<BARRIER_BUCKETS_NR_BITS)
28
29/* Note: raid1_info.rdev can be set to NULL asynchronously by raid1_remove_disk.
30 * There are three safe ways to access raid1_info.rdev.
31 * 1/ when holding mddev->reconfig_mutex
32 * 2/ when resync/recovery is known to be happening - i.e. in code that is
33 *    called as part of performing resync/recovery.
34 * 3/ while holding rcu_read_lock(), use rcu_dereference to get the pointer
35 *    and if it is non-NULL, increment rdev->nr_pending before dropping the
36 *    RCU lock.
37 * When .rdev is set to NULL, the nr_pending count checked again and if it has
38 * been incremented, the pointer is put back in .rdev.
39 */
40
41struct raid1_info {
42	struct md_rdev	*rdev;
43	sector_t	head_position;
44
45	/* When choose the best device for a read (read_balance())
46	 * we try to keep sequential reads one the same device
47	 */
48	sector_t	next_seq_sect;
49	sector_t	seq_start;
50};
51
52/*
53 * memory pools need a pointer to the mddev, so they can force an unplug
54 * when memory is tight, and a count of the number of drives that the
55 * pool was allocated for, so they know how much to allocate and free.
56 * mddev->raid_disks cannot be used, as it can change while a pool is active
57 * These two datums are stored in a kmalloced struct.
58 * The 'raid_disks' here is twice the raid_disks in r1conf.
59 * This allows space for each 'real' device can have a replacement in the
60 * second half of the array.
61 */
62
63struct pool_info {
64	struct mddev *mddev;
65	int	raid_disks;
66};
67
68struct r1conf {
69	struct mddev		*mddev;
70	struct raid1_info	*mirrors;	/* twice 'raid_disks' to
71						 * allow for replacements.
72						 */
73	int			raid_disks;
74	int			nonrot_disks;
75
76	spinlock_t		device_lock;
77
78	/* list of 'struct r1bio' that need to be processed by raid1d,
79	 * whether to retry a read, writeout a resync or recovery
80	 * block, or anything else.
81	 */
82	struct list_head	retry_list;
83	/* A separate list of r1bio which just need raid_end_bio_io called.
84	 * This mustn't happen for writes which had any errors if the superblock
85	 * needs to be written.
86	 */
87	struct list_head	bio_end_io_list;
88
89	/* queue pending writes to be submitted on unplug */
90	struct bio_list		pending_bio_list;
91
92	/* for use when syncing mirrors:
93	 * We don't allow both normal IO and resync/recovery IO at
94	 * the same time - resync/recovery can only happen when there
95	 * is no other IO.  So when either is active, the other has to wait.
96	 * See more details description in raid1.c near raise_barrier().
97	 */
98	wait_queue_head_t	wait_barrier;
99	spinlock_t		resync_lock;
100	atomic_t		nr_sync_pending;
101	atomic_t		*nr_pending;
102	atomic_t		*nr_waiting;
103	atomic_t		*nr_queued;
104	atomic_t		*barrier;
105	int			array_frozen;
106
107	/* Set to 1 if a full sync is needed, (fresh device added).
108	 * Cleared when a sync completes.
109	 */
110	int			fullsync;
111
112	/* When the same as mddev->recovery_disabled we don't allow
113	 * recovery to be attempted as we expect a read error.
114	 */
115	int			recovery_disabled;
116
117	/* poolinfo contains information about the content of the
118	 * mempools - it changes when the array grows or shrinks
119	 */
120	struct pool_info	*poolinfo;
121	mempool_t		r1bio_pool;
122	mempool_t		r1buf_pool;
123
124	struct bio_set		bio_split;
125
126	/* temporary buffer to synchronous IO when attempting to repair
127	 * a read error.
128	 */
129	struct page		*tmppage;
130
131	/* When taking over an array from a different personality, we store
132	 * the new thread here until we fully activate the array.
133	 */
134	struct md_thread __rcu	*thread;
135
136	/* Keep track of cluster resync window to send to other
137	 * nodes.
138	 */
139	sector_t		cluster_sync_low;
140	sector_t		cluster_sync_high;
141
142};
143
144/*
145 * this is our 'private' RAID1 bio.
146 *
147 * it contains information about what kind of IO operations were started
148 * for this RAID1 operation, and about their status:
149 */
150
151struct r1bio {
152	atomic_t		remaining; /* 'have we finished' count,
153					    * used from IRQ handlers
154					    */
155	atomic_t		behind_remaining; /* number of write-behind ios remaining
156						 * in this BehindIO request
157						 */
158	sector_t		sector;
159	int			sectors;
160	unsigned long		state;
161	struct mddev		*mddev;
162	/*
163	 * original bio going to /dev/mdx
164	 */
165	struct bio		*master_bio;
166	/*
167	 * if the IO is in READ direction, then this is where we read
168	 */
169	int			read_disk;
170
171	struct list_head	retry_list;
172
173	/*
174	 * When R1BIO_BehindIO is set, we store pages for write behind
175	 * in behind_master_bio.
176	 */
177	struct bio		*behind_master_bio;
178
179	/*
180	 * if the IO is in WRITE direction, then multiple bios are used.
181	 * We choose the number when they are allocated.
182	 */
183	struct bio		*bios[];
184	/* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
185};
186
187/* bits for r1bio.state */
188enum r1bio_state {
189	R1BIO_Uptodate,
190	R1BIO_IsSync,
191	R1BIO_Degraded,
192	R1BIO_BehindIO,
193/* Set ReadError on bios that experience a readerror so that
194 * raid1d knows what to do with them.
195 */
196	R1BIO_ReadError,
197/* For write-behind requests, we call bi_end_io when
198 * the last non-write-behind device completes, providing
199 * any write was successful.  Otherwise we call when
200 * any write-behind write succeeds, otherwise we call
201 * with failure when last write completes (and all failed).
202 * Record that bi_end_io was called with this flag...
203 */
204	R1BIO_Returned,
205/* If a write for this request means we can clear some
206 * known-bad-block records, we set this flag
207 */
208	R1BIO_MadeGood,
209	R1BIO_WriteError,
210	R1BIO_FailFast,
211};
212
213static inline int sector_to_idx(sector_t sector)
214{
215	return hash_long(sector >> BARRIER_UNIT_SECTOR_BITS,
216			 BARRIER_BUCKETS_NR_BITS);
217}
218#endif
219