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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2018-2023 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <djwong@kernel.org>
*/
#include "xfs.h"
#include "xfs_shared.h"
#include "xfs_bit.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_btree.h"
#include "bitmap.h"
#include "scrub/agb_bitmap.h"
/*
* 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_levels[0].ptr == 1, so we
* record that we saw block 1. Then we observe that bc_levels[1].ptr == 1, so
* we record block 4. The list is [1, 4].
*
* For the second btree record, we see that bc_levels[0].ptr == 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_levels[0].ptr == 1 again, so we record that we saw block 2. We see that
* bc_levels[1].ptr == 2, so we exit the loop. The list is now [1, 4, 2].
*
* For the 102nd record, bc_levels[0].ptr == 2, so we continue.
*
* For the 201st record, we've moved on to leaf block 3.
* bc_levels[0].ptr == 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].
*/
/* Mark a btree block to the agblock bitmap. */
STATIC int
xagb_bitmap_visit_btblock(
struct xfs_btree_cur *cur,
int level,
void *priv)
{
struct xagb_bitmap *bitmap = priv;
struct xfs_buf *bp;
xfs_fsblock_t fsbno;
xfs_agblock_t agbno;
xfs_btree_get_block(cur, level, &bp);
if (!bp)
return 0;
fsbno = XFS_DADDR_TO_FSB(cur->bc_mp, xfs_buf_daddr(bp));
agbno = XFS_FSB_TO_AGBNO(cur->bc_mp, fsbno);
return xagb_bitmap_set(bitmap, agbno, 1);
}
/* Mark all (per-AG) btree blocks in the agblock bitmap. */
int
xagb_bitmap_set_btblocks(
struct xagb_bitmap *bitmap,
struct xfs_btree_cur *cur)
{
return xfs_btree_visit_blocks(cur, xagb_bitmap_visit_btblock,
XFS_BTREE_VISIT_ALL, bitmap);
}
/*
* 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
xagb_bitmap_set_btcur_path(
struct xagb_bitmap *bitmap,
struct xfs_btree_cur *cur)
{
int i;
int error;
for (i = 0; i < cur->bc_nlevels && cur->bc_levels[i].ptr == 1; i++) {
error = xagb_bitmap_visit_btblock(cur, i, bitmap);
if (error)
return error;
}
return 0;
}
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