/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Copyright (C) 2020 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <darrick.wong@oracle.com>
 */
#ifndef __XFS_BTREE_STAGING_H__
#define __XFS_BTREE_STAGING_H__

/* Fake root for an AG-rooted btree. */
struct xbtree_afakeroot {
        /* AG block number of the new btree root. */
        xfs_agblock_t           af_root;

        /* Height of the new btree. */
        unsigned int            af_levels;

        /* Number of blocks used by the btree. */
        unsigned int            af_blocks;
};

/* Cursor interactions with fake roots for AG-rooted btrees. */
void xfs_btree_stage_afakeroot(struct xfs_btree_cur *cur,
                struct xbtree_afakeroot *afake);
void xfs_btree_commit_afakeroot(struct xfs_btree_cur *cur, struct xfs_trans *tp,
                struct xfs_buf *agbp);

/* Fake root for an inode-rooted btree. */
struct xbtree_ifakeroot {
        /* Fake inode fork. */
        struct xfs_ifork        *if_fork;

        /* Number of blocks used by the btree. */
        int64_t                 if_blocks;

        /* Height of the new btree. */
        unsigned int            if_levels;

        /* Number of bytes available for this fork in the inode. */
        unsigned int            if_fork_size;
};

/* Cursor interactions with fake roots for inode-rooted btrees. */
void xfs_btree_stage_ifakeroot(struct xfs_btree_cur *cur,
                struct xbtree_ifakeroot *ifake);
void xfs_btree_commit_ifakeroot(struct xfs_btree_cur *cur, struct xfs_trans *tp,
                int whichfork);

/* Bulk loading of staged btrees. */
typedef int (*xfs_btree_bload_get_records_fn)(struct xfs_btree_cur *cur,
                unsigned int idx, struct xfs_btree_block *block,
                unsigned int nr_wanted, void *priv);
typedef int (*xfs_btree_bload_claim_block_fn)(struct xfs_btree_cur *cur,
                union xfs_btree_ptr *ptr, void *priv);
typedef size_t (*xfs_btree_bload_iroot_size_fn)(struct xfs_btree_cur *cur,
                unsigned int level, unsigned int nr_this_level, void *priv);

struct xfs_btree_bload {
        /*
         * This function will be called to load @nr_wanted records into the
         * btree.  The implementation does this by setting the cursor's bc_rec
         * field in in-core format and using init_rec_from_cur to set the
         * records in the btree block.  Records must be returned in sort order.
         * The function must return the number of records loaded or the usual
         * negative errno.
         */
        xfs_btree_bload_get_records_fn  get_records;

        /*
         * This function will be called nr_blocks times to obtain a pointer
         * to a new btree block on disk.  Callers must preallocate all space
         * for the new btree before calling xfs_btree_bload, and this function
         * is what claims that reservation.
         */
        xfs_btree_bload_claim_block_fn  claim_block;

        /*
         * This function should return the size of the in-core btree root
         * block.  It is only necessary for XFS_BTREE_TYPE_INODE btrees.
         */
        xfs_btree_bload_iroot_size_fn   iroot_size;

        /*
         * The caller should set this to the number of records that will be
         * stored in the new btree.
         */
        uint64_t                        nr_records;

        /*
         * Number of free records to leave in each leaf block.  If the caller
         * sets this to -1, the slack value will be calculated to be halfway
         * between maxrecs and minrecs.  This typically leaves the block 75%
         * full.  Note that slack values are not enforced on inode root blocks.
         */
        int                             leaf_slack;

        /*
         * Number of free key/ptrs pairs to leave in each node block.  This
         * field has the same semantics as leaf_slack.
         */
        int                             node_slack;

        /*
         * The xfs_btree_bload_compute_geometry function will set this to the
         * number of btree blocks needed to store nr_records records.
         */
        uint64_t                        nr_blocks;

        /*
         * The xfs_btree_bload_compute_geometry function will set this to the
         * height of the new btree.
         */
        unsigned int                    btree_height;

        /*
         * Flush the new btree block buffer list to disk after this many blocks
         * have been formatted.  Zero prohibits writing any buffers until all
         * blocks have been formatted.
         */
        uint16_t                        max_dirty;

        /* Number of dirty buffers. */
        uint16_t                        nr_dirty;
};

int xfs_btree_bload_compute_geometry(struct xfs_btree_cur *cur,
                struct xfs_btree_bload *bbl, uint64_t nr_records);
int xfs_btree_bload(struct xfs_btree_cur *cur, struct xfs_btree_bload *bbl,
                void *priv);

#endif  /* __XFS_BTREE_STAGING_H__ */