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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2020 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_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_btree.h"
#include "xfs_trace.h"
#include "xfs_btree_staging.h"
/*
* Staging Cursors and Fake Roots for Btrees
* =========================================
*
* A staging btree cursor is a special type of btree cursor that callers must
* use to construct a new btree index using the btree bulk loader code. The
* bulk loading code uses the staging btree cursor to abstract the details of
* initializing new btree blocks and filling them with records or key/ptr
* pairs. Regular btree operations (e.g. queries and modifications) are not
* supported with staging cursors, and callers must not invoke them.
*
* Fake root structures contain all the information about a btree that is under
* construction by the bulk loading code. Staging btree cursors point to fake
* root structures instead of the usual AG header or inode structure.
*
* Callers are expected to initialize a fake root structure and pass it into
* the _stage_cursor function for a specific btree type. When bulk loading is
* complete, callers should call the _commit_staged_btree function for that
* specific btree type to commit the new btree into the filesystem.
*/
/*
* Don't allow staging cursors to be duplicated because they're supposed to be
* kept private to a single thread.
*/
STATIC struct xfs_btree_cur *
xfs_btree_fakeroot_dup_cursor(
struct xfs_btree_cur *cur)
{
ASSERT(0);
return NULL;
}
/*
* Don't allow block allocation for a staging cursor, because staging cursors
* do not support regular btree modifications.
*
* Bulk loading uses a separate callback to obtain new blocks from a
* preallocated list, which prevents ENOSPC failures during loading.
*/
STATIC int
xfs_btree_fakeroot_alloc_block(
struct xfs_btree_cur *cur,
union xfs_btree_ptr *start_bno,
union xfs_btree_ptr *new_bno,
int *stat)
{
ASSERT(0);
return -EFSCORRUPTED;
}
/*
* Don't allow block freeing for a staging cursor, because staging cursors
* do not support regular btree modifications.
*/
STATIC int
xfs_btree_fakeroot_free_block(
struct xfs_btree_cur *cur,
struct xfs_buf *bp)
{
ASSERT(0);
return -EFSCORRUPTED;
}
/* Initialize a pointer to the root block from the fakeroot. */
STATIC void
xfs_btree_fakeroot_init_ptr_from_cur(
struct xfs_btree_cur *cur,
union xfs_btree_ptr *ptr)
{
struct xbtree_afakeroot *afake;
ASSERT(cur->bc_flags & XFS_BTREE_STAGING);
afake = cur->bc_ag.afake;
ptr->s = cpu_to_be32(afake->af_root);
}
/*
* Bulk Loading for AG Btrees
* ==========================
*
* For a btree rooted in an AG header, pass a xbtree_afakeroot structure to the
* staging cursor. Callers should initialize this to zero.
*
* The _stage_cursor() function for a specific btree type should call
* xfs_btree_stage_afakeroot to set up the in-memory cursor as a staging
* cursor. The corresponding _commit_staged_btree() function should log the
* new root and call xfs_btree_commit_afakeroot() to transform the staging
* cursor into a regular btree cursor.
*/
/* Update the btree root information for a per-AG fake root. */
STATIC void
xfs_btree_afakeroot_set_root(
struct xfs_btree_cur *cur,
union xfs_btree_ptr *ptr,
int inc)
{
struct xbtree_afakeroot *afake = cur->bc_ag.afake;
ASSERT(cur->bc_flags & XFS_BTREE_STAGING);
afake->af_root = be32_to_cpu(ptr->s);
afake->af_levels += inc;
}
/*
* Initialize a AG-rooted btree cursor with the given AG btree fake root.
* The btree cursor's bc_ops will be overridden as needed to make the staging
* functionality work.
*/
void
xfs_btree_stage_afakeroot(
struct xfs_btree_cur *cur,
struct xbtree_afakeroot *afake)
{
struct xfs_btree_ops *nops;
ASSERT(!(cur->bc_flags & XFS_BTREE_STAGING));
ASSERT(!(cur->bc_flags & XFS_BTREE_ROOT_IN_INODE));
ASSERT(cur->bc_tp == NULL);
nops = kmem_alloc(sizeof(struct xfs_btree_ops), KM_NOFS);
memcpy(nops, cur->bc_ops, sizeof(struct xfs_btree_ops));
nops->alloc_block = xfs_btree_fakeroot_alloc_block;
nops->free_block = xfs_btree_fakeroot_free_block;
nops->init_ptr_from_cur = xfs_btree_fakeroot_init_ptr_from_cur;
nops->set_root = xfs_btree_afakeroot_set_root;
nops->dup_cursor = xfs_btree_fakeroot_dup_cursor;
cur->bc_ag.afake = afake;
cur->bc_nlevels = afake->af_levels;
cur->bc_ops = nops;
cur->bc_flags |= XFS_BTREE_STAGING;
}
/*
* Transform an AG-rooted staging btree cursor back into a regular cursor by
* substituting a real btree root for the fake one and restoring normal btree
* cursor ops. The caller must log the btree root change prior to calling
* this.
*/
void
xfs_btree_commit_afakeroot(
struct xfs_btree_cur *cur,
struct xfs_trans *tp,
struct xfs_buf *agbp,
const struct xfs_btree_ops *ops)
{
ASSERT(cur->bc_flags & XFS_BTREE_STAGING);
ASSERT(cur->bc_tp == NULL);
trace_xfs_btree_commit_afakeroot(cur);
kmem_free((void *)cur->bc_ops);
cur->bc_ag.agbp = agbp;
cur->bc_ops = ops;
cur->bc_flags &= ~XFS_BTREE_STAGING;
cur->bc_tp = tp;
}
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