summaryrefslogtreecommitdiff
path: root/fs/xfs/scrub/bitmap.c
blob: 813b5f21911387e32045ba65daadafd9a51e1389 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2018 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <darrick.wong@oracle.com>
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_btree.h"
#include "scrub/bitmap.h"

/*
 * Set a range of this bitmap.  Caller must ensure the range is not set.
 *
 * This is the logical equivalent of bitmap |= mask(start, len).
 */
int
xbitmap_set(
	struct xbitmap		*bitmap,
	uint64_t		start,
	uint64_t		len)
{
	struct xbitmap_range	*bmr;

	bmr = kmem_alloc(sizeof(struct xbitmap_range), KM_MAYFAIL);
	if (!bmr)
		return -ENOMEM;

	INIT_LIST_HEAD(&bmr->list);
	bmr->start = start;
	bmr->len = len;
	list_add_tail(&bmr->list, &bitmap->list);

	return 0;
}

/* Free everything related to this bitmap. */
void
xbitmap_destroy(
	struct xbitmap		*bitmap)
{
	struct xbitmap_range	*bmr;
	struct xbitmap_range	*n;

	for_each_xbitmap_extent(bmr, n, bitmap) {
		list_del(&bmr->list);
		kmem_free(bmr);
	}
}

/* Set up a per-AG block bitmap. */
void
xbitmap_init(
	struct xbitmap		*bitmap)
{
	INIT_LIST_HEAD(&bitmap->list);
}

/* Compare two btree extents. */
static int
xbitmap_range_cmp(
	void			*priv,
	const struct list_head	*a,
	const struct list_head	*b)
{
	struct xbitmap_range	*ap;
	struct xbitmap_range	*bp;

	ap = container_of(a, struct xbitmap_range, list);
	bp = container_of(b, struct xbitmap_range, list);

	if (ap->start > bp->start)
		return 1;
	if (ap->start < bp->start)
		return -1;
	return 0;
}

/*
 * Remove all the blocks mentioned in @sub from the extents in @bitmap.
 *
 * The intent is that callers will iterate the rmapbt for all of its records
 * for a given owner to generate @bitmap; and iterate all the blocks of the
 * metadata structures that are not being rebuilt and have the same rmapbt
 * owner to generate @sub.  This routine subtracts all the extents
 * mentioned in sub from all the extents linked in @bitmap, which leaves
 * @bitmap as the list of blocks that are not accounted for, which we assume
 * are the dead blocks of the old metadata structure.  The blocks mentioned in
 * @bitmap can be reaped.
 *
 * This is the logical equivalent of bitmap &= ~sub.
 */
#define LEFT_ALIGNED	(1 << 0)
#define RIGHT_ALIGNED	(1 << 1)
int
xbitmap_disunion(
	struct xbitmap		*bitmap,
	struct xbitmap		*sub)
{
	struct list_head	*lp;
	struct xbitmap_range	*br;
	struct xbitmap_range	*new_br;
	struct xbitmap_range	*sub_br;
	uint64_t		sub_start;
	uint64_t		sub_len;
	int			state;
	int			error = 0;

	if (list_empty(&bitmap->list) || list_empty(&sub->list))
		return 0;
	ASSERT(!list_empty(&sub->list));

	list_sort(NULL, &bitmap->list, xbitmap_range_cmp);
	list_sort(NULL, &sub->list, xbitmap_range_cmp);

	/*
	 * Now that we've sorted both lists, we iterate bitmap once, rolling
	 * forward through sub and/or bitmap as necessary until we find an
	 * overlap or reach the end of either list.  We do not reset lp to the
	 * head of bitmap nor do we reset sub_br to the head of sub.  The
	 * list traversal is similar to merge sort, but we're deleting
	 * instead.  In this manner we avoid O(n^2) operations.
	 */
	sub_br = list_first_entry(&sub->list, struct xbitmap_range,
			list);
	lp = bitmap->list.next;
	while (lp != &bitmap->list) {
		br = list_entry(lp, struct xbitmap_range, list);

		/*
		 * Advance sub_br and/or br until we find a pair that
		 * intersect or we run out of extents.
		 */
		while (sub_br->start + sub_br->len <= br->start) {
			if (list_is_last(&sub_br->list, &sub->list))
				goto out;
			sub_br = list_next_entry(sub_br, list);
		}
		if (sub_br->start >= br->start + br->len) {
			lp = lp->next;
			continue;
		}

		/* trim sub_br to fit the extent we have */
		sub_start = sub_br->start;
		sub_len = sub_br->len;
		if (sub_br->start < br->start) {
			sub_len -= br->start - sub_br->start;
			sub_start = br->start;
		}
		if (sub_len > br->len)
			sub_len = br->len;

		state = 0;
		if (sub_start == br->start)
			state |= LEFT_ALIGNED;
		if (sub_start + sub_len == br->start + br->len)
			state |= RIGHT_ALIGNED;
		switch (state) {
		case LEFT_ALIGNED:
			/* Coincides with only the left. */
			br->start += sub_len;
			br->len -= sub_len;
			break;
		case RIGHT_ALIGNED:
			/* Coincides with only the right. */
			br->len -= sub_len;
			lp = lp->next;
			break;
		case LEFT_ALIGNED | RIGHT_ALIGNED:
			/* Total overlap, just delete ex. */
			lp = lp->next;
			list_del(&br->list);
			kmem_free(br);
			break;
		case 0:
			/*
			 * Deleting from the middle: add the new right extent
			 * and then shrink the left extent.
			 */
			new_br = kmem_alloc(sizeof(struct xbitmap_range),
					KM_MAYFAIL);
			if (!new_br) {
				error = -ENOMEM;
				goto out;
			}
			INIT_LIST_HEAD(&new_br->list);
			new_br->start = sub_start + sub_len;
			new_br->len = br->start + br->len - new_br->start;
			list_add(&new_br->list, &br->list);
			br->len = sub_start - br->start;
			lp = lp->next;
			break;
		default:
			ASSERT(0);
			break;
		}
	}

out:
	return error;
}
#undef LEFT_ALIGNED
#undef RIGHT_ALIGNED

/*
 * Record all btree blocks seen while iterating all records of a btree.
 *
 * We know that the btree query_all function starts at the left edge and walks
 * towards the right edge of the tree.  Therefore, we know that we can walk up
 * the btree cursor towards the root; if the pointer for a given level points
 * to the first record/key in that block, we haven't seen this block before;
 * and therefore we need to remember that we saw this block in the btree.
 *
 * So if our btree is:
 *
 *    4
 *  / | \
 * 1  2  3
 *
 * Pretend for this example that each leaf block has 100 btree records.  For
 * the first btree record, we'll observe that bc_ptrs[0] == 1, so we record
 * that we saw block 1.  Then we observe that bc_ptrs[1] == 1, so we record
 * block 4.  The list is [1, 4].
 *
 * For the second btree record, we see that bc_ptrs[0] == 2, so we exit the
 * loop.  The list remains [1, 4].
 *
 * For the 101st btree record, we've moved onto leaf block 2.  Now
 * bc_ptrs[0] == 1 again, so we record that we saw block 2.  We see that
 * bc_ptrs[1] == 2, so we exit the loop.  The list is now [1, 4, 2].
 *
 * For the 102nd record, bc_ptrs[0] == 2, so we continue.
 *
 * For the 201st record, we've moved on to leaf block 3.  bc_ptrs[0] == 1, so
 * we add 3 to the list.  Now it is [1, 4, 2, 3].
 *
 * For the 300th record we just exit, with the list being [1, 4, 2, 3].
 */

/*
 * Record all the buffers pointed to by the btree cursor.  Callers already
 * engaged in a btree walk should call this function to capture the list of
 * blocks going from the leaf towards the root.
 */
int
xbitmap_set_btcur_path(
	struct xbitmap		*bitmap,
	struct xfs_btree_cur	*cur)
{
	struct xfs_buf		*bp;
	xfs_fsblock_t		fsb;
	int			i;
	int			error;

	for (i = 0; i < cur->bc_nlevels && cur->bc_ptrs[i] == 1; i++) {
		xfs_btree_get_block(cur, i, &bp);
		if (!bp)
			continue;
		fsb = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
		error = xbitmap_set(bitmap, fsb, 1);
		if (error)
			return error;
	}

	return 0;
}

/* Collect a btree's block in the bitmap. */
STATIC int
xbitmap_collect_btblock(
	struct xfs_btree_cur	*cur,
	int			level,
	void			*priv)
{
	struct xbitmap		*bitmap = priv;
	struct xfs_buf		*bp;
	xfs_fsblock_t		fsbno;

	xfs_btree_get_block(cur, level, &bp);
	if (!bp)
		return 0;

	fsbno = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
	return xbitmap_set(bitmap, fsbno, 1);
}

/* Walk the btree and mark the bitmap wherever a btree block is found. */
int
xbitmap_set_btblocks(
	struct xbitmap		*bitmap,
	struct xfs_btree_cur	*cur)
{
	return xfs_btree_visit_blocks(cur, xbitmap_collect_btblock,
			XFS_BTREE_VISIT_ALL, bitmap);
}

/* How many bits are set in this bitmap? */
uint64_t
xbitmap_hweight(
	struct xbitmap		*bitmap)
{
	struct xbitmap_range	*bmr;
	struct xbitmap_range	*n;
	uint64_t		ret = 0;

	for_each_xbitmap_extent(bmr, n, bitmap)
		ret += bmr->len;

	return ret;
}