1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2018-2023 Oracle.  All Rights Reserved.
4 * Author: Darrick J. Wong <djwong@kernel.org>
5 */
6#include "xfs.h"
7#include "xfs_shared.h"
8#include "xfs_bit.h"
9#include "xfs_format.h"
10#include "xfs_trans_resv.h"
11#include "xfs_mount.h"
12#include "xfs_btree.h"
13#include "bitmap.h"
14#include "scrub/agb_bitmap.h"
15
16/*
17 * Record all btree blocks seen while iterating all records of a btree.
18 *
19 * We know that the btree query_all function starts at the left edge and walks
20 * towards the right edge of the tree.  Therefore, we know that we can walk up
21 * the btree cursor towards the root; if the pointer for a given level points
22 * to the first record/key in that block, we haven't seen this block before;
23 * and therefore we need to remember that we saw this block in the btree.
24 *
25 * So if our btree is:
26 *
27 *    4
28 *  / | \
29 * 1  2  3
30 *
31 * Pretend for this example that each leaf block has 100 btree records.  For
32 * the first btree record, we'll observe that bc_levels[0].ptr == 1, so we
33 * record that we saw block 1.  Then we observe that bc_levels[1].ptr == 1, so
34 * we record block 4.  The list is [1, 4].
35 *
36 * For the second btree record, we see that bc_levels[0].ptr == 2, so we exit
37 * the loop.  The list remains [1, 4].
38 *
39 * For the 101st btree record, we've moved onto leaf block 2.  Now
40 * bc_levels[0].ptr == 1 again, so we record that we saw block 2.  We see that
41 * bc_levels[1].ptr == 2, so we exit the loop.  The list is now [1, 4, 2].
42 *
43 * For the 102nd record, bc_levels[0].ptr == 2, so we continue.
44 *
45 * For the 201st record, we've moved on to leaf block 3.
46 * bc_levels[0].ptr == 1, so we add 3 to the list.  Now it is [1, 4, 2, 3].
47 *
48 * For the 300th record we just exit, with the list being [1, 4, 2, 3].
49 */
50
51/* Mark a btree block to the agblock bitmap. */
52STATIC int
53xagb_bitmap_visit_btblock(
54	struct xfs_btree_cur	*cur,
55	int			level,
56	void			*priv)
57{
58	struct xagb_bitmap	*bitmap = priv;
59	struct xfs_buf		*bp;
60	xfs_fsblock_t		fsbno;
61	xfs_agblock_t		agbno;
62
63	xfs_btree_get_block(cur, level, &bp);
64	if (!bp)
65		return 0;
66
67	fsbno = XFS_DADDR_TO_FSB(cur->bc_mp, xfs_buf_daddr(bp));
68	agbno = XFS_FSB_TO_AGBNO(cur->bc_mp, fsbno);
69
70	return xagb_bitmap_set(bitmap, agbno, 1);
71}
72
73/* Mark all (per-AG) btree blocks in the agblock bitmap. */
74int
75xagb_bitmap_set_btblocks(
76	struct xagb_bitmap	*bitmap,
77	struct xfs_btree_cur	*cur)
78{
79	return xfs_btree_visit_blocks(cur, xagb_bitmap_visit_btblock,
80			XFS_BTREE_VISIT_ALL, bitmap);
81}
82
83/*
84 * Record all the buffers pointed to by the btree cursor.  Callers already
85 * engaged in a btree walk should call this function to capture the list of
86 * blocks going from the leaf towards the root.
87 */
88int
89xagb_bitmap_set_btcur_path(
90	struct xagb_bitmap	*bitmap,
91	struct xfs_btree_cur	*cur)
92{
93	int			i;
94	int			error;
95
96	for (i = 0; i < cur->bc_nlevels && cur->bc_levels[i].ptr == 1; i++) {
97		error = xagb_bitmap_visit_btblock(cur, i, bitmap);
98		if (error)
99			return error;
100	}
101
102	return 0;
103}
104