104 lines
2.9 KiB
C
104 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2018-2023 Oracle. All Rights Reserved.
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* Author: Darrick J. Wong <djwong@kernel.org>
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*/
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#include "xfs.h"
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#include "xfs_shared.h"
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#include "xfs_bit.h"
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#include "xfs_format.h"
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#include "xfs_trans_resv.h"
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#include "xfs_mount.h"
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#include "xfs_btree.h"
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#include "bitmap.h"
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#include "scrub/agb_bitmap.h"
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/*
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* Record all btree blocks seen while iterating all records of a btree.
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*
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* We know that the btree query_all function starts at the left edge and walks
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* towards the right edge of the tree. Therefore, we know that we can walk up
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* the btree cursor towards the root; if the pointer for a given level points
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* to the first record/key in that block, we haven't seen this block before;
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* and therefore we need to remember that we saw this block in the btree.
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*
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* So if our btree is:
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*
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* 4
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* / | \
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* 1 2 3
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*
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* Pretend for this example that each leaf block has 100 btree records. For
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* the first btree record, we'll observe that bc_levels[0].ptr == 1, so we
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* record that we saw block 1. Then we observe that bc_levels[1].ptr == 1, so
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* we record block 4. The list is [1, 4].
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*
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* For the second btree record, we see that bc_levels[0].ptr == 2, so we exit
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* the loop. The list remains [1, 4].
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*
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* For the 101st btree record, we've moved onto leaf block 2. Now
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* bc_levels[0].ptr == 1 again, so we record that we saw block 2. We see that
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* bc_levels[1].ptr == 2, so we exit the loop. The list is now [1, 4, 2].
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*
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* For the 102nd record, bc_levels[0].ptr == 2, so we continue.
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*
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* For the 201st record, we've moved on to leaf block 3.
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* bc_levels[0].ptr == 1, so we add 3 to the list. Now it is [1, 4, 2, 3].
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*
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* For the 300th record we just exit, with the list being [1, 4, 2, 3].
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*/
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/* Mark a btree block to the agblock bitmap. */
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STATIC int
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xagb_bitmap_visit_btblock(
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struct xfs_btree_cur *cur,
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int level,
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void *priv)
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{
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struct xagb_bitmap *bitmap = priv;
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struct xfs_buf *bp;
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xfs_fsblock_t fsbno;
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xfs_agblock_t agbno;
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xfs_btree_get_block(cur, level, &bp);
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if (!bp)
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return 0;
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fsbno = XFS_DADDR_TO_FSB(cur->bc_mp, xfs_buf_daddr(bp));
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agbno = XFS_FSB_TO_AGBNO(cur->bc_mp, fsbno);
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return xagb_bitmap_set(bitmap, agbno, 1);
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}
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/* Mark all (per-AG) btree blocks in the agblock bitmap. */
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int
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xagb_bitmap_set_btblocks(
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struct xagb_bitmap *bitmap,
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struct xfs_btree_cur *cur)
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{
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return xfs_btree_visit_blocks(cur, xagb_bitmap_visit_btblock,
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XFS_BTREE_VISIT_ALL, bitmap);
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}
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/*
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* Record all the buffers pointed to by the btree cursor. Callers already
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* engaged in a btree walk should call this function to capture the list of
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* blocks going from the leaf towards the root.
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*/
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int
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xagb_bitmap_set_btcur_path(
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struct xagb_bitmap *bitmap,
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struct xfs_btree_cur *cur)
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{
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int i;
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int error;
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for (i = 0; i < cur->bc_nlevels && cur->bc_levels[i].ptr == 1; i++) {
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error = xagb_bitmap_visit_btblock(cur, i, bitmap);
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if (error)
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return error;
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}
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return 0;
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}
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