// SPDX-License-Identifier: GPL-2.0+
/*
 * Dummy inodes to buffer blocks for garbage collection
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * Written by Seiji Kihara, Amagai Yoshiji, and Ryusuke Konishi.
 * Revised by Ryusuke Konishi.
 *
 */
/*
 * This file adds the cache of on-disk blocks to be moved in garbage
 * collection.  The disk blocks are held with dummy inodes (called
 * gcinodes), and this file provides lookup function of the dummy
 * inodes and their buffer read function.
 *
 * Buffers and pages held by the dummy inodes will be released each
 * time after they are copied to a new log.  Dirty blocks made on the
 * current generation and the blocks to be moved by GC never overlap
 * because the dirty blocks make a new generation; they rather must be
 * written individually.
 */

#include <linux/buffer_head.h>
#include <linux/mpage.h>
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include "nilfs.h"
#include "btree.h"
#include "btnode.h"
#include "page.h"
#include "mdt.h"
#include "dat.h"
#include "ifile.h"

/*
 * nilfs_gccache_submit_read_data() - add data buffer and submit read request
 * @inode - gc inode
 * @blkoff - dummy offset treated as the key for the page cache
 * @pbn - physical block number of the block
 * @vbn - virtual block number of the block, 0 for non-virtual block
 * @out_bh - indirect pointer to a buffer_head struct to receive the results
 *
 * Description: nilfs_gccache_submit_read_data() registers the data buffer
 * specified by @pbn to the GC pagecache with the key @blkoff.
 * This function sets @vbn (@pbn if @vbn is zero) in b_blocknr of the buffer.
 *
 * Return: 0 on success, or one of the following negative error codes on
 * failure:
 * * %-EIO      - I/O error (including metadata corruption).
 * * %-ENOENT   - The block specified with @pbn does not exist.
 * * %-ENOMEM   - Insufficient memory available.
 */
int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
                                   sector_t pbn, __u64 vbn,
                                   struct buffer_head **out_bh)
{
        struct buffer_head *bh;
        int err;

        bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
        if (unlikely(!bh))
                return -ENOMEM;

        if (buffer_uptodate(bh))
                goto out;

        if (pbn == 0) {
                struct the_nilfs *nilfs = inode->i_sb->s_fs_info;

                err = nilfs_dat_translate(nilfs->ns_dat, vbn, &pbn);
                if (unlikely(err)) /* -EIO, -ENOMEM, -ENOENT */
                        goto failed;
        }

        lock_buffer(bh);
        if (buffer_uptodate(bh)) {
                unlock_buffer(bh);
                goto out;
        }

        if (!buffer_mapped(bh))
                set_buffer_mapped(bh);
        bh->b_blocknr = pbn;
        bh->b_end_io = end_buffer_read_sync;
        get_bh(bh);
        submit_bh(REQ_OP_READ, bh);
        if (vbn)
                bh->b_blocknr = vbn;
 out:
        err = 0;
        *out_bh = bh;

 failed:
        folio_unlock(bh->b_folio);
        folio_put(bh->b_folio);
        if (unlikely(err))
                brelse(bh);
        return err;
}

/*
 * nilfs_gccache_submit_read_node() - add node buffer and submit read request
 * @inode - gc inode
 * @pbn - physical block number for the block
 * @vbn - virtual block number for the block
 * @out_bh - indirect pointer to a buffer_head struct to receive the results
 *
 * Description: nilfs_gccache_submit_read_node() registers the node buffer
 * specified by @vbn to the GC pagecache.  @pbn can be supplied by the
 * caller to avoid translation of the disk block address.
 *
 * Return: 0 on success, or one of the following negative error codes on
 * failure:
 * * %-EIO      - I/O error (including metadata corruption).
 * * %-ENOENT   - Invalid virtual block address.
 * * %-ENOMEM   - Insufficient memory available.
 */
int nilfs_gccache_submit_read_node(struct inode *inode, sector_t pbn,
                                   __u64 vbn, struct buffer_head **out_bh)
{
        struct inode *btnc_inode = NILFS_I(inode)->i_assoc_inode;
        int ret;

        ret = nilfs_btnode_submit_block(btnc_inode->i_mapping, vbn ? : pbn, pbn,
                                        REQ_OP_READ, out_bh, &pbn);
        if (ret == -EEXIST) /* internal code (cache hit) */
                ret = 0;
        return ret;
}

int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *bh)
{
        wait_on_buffer(bh);
        if (!buffer_uptodate(bh)) {
                struct inode *inode = bh->b_folio->mapping->host;

                nilfs_err(inode->i_sb,
                          "I/O error reading %s block for GC (ino=%lu, vblocknr=%llu)",
                          buffer_nilfs_node(bh) ? "node" : "data",
                          inode->i_ino, (unsigned long long)bh->b_blocknr);
                return -EIO;
        }
        if (buffer_dirty(bh))
                return -EEXIST;

        if (buffer_nilfs_node(bh) && nilfs_btree_broken_node_block(bh)) {
                clear_buffer_uptodate(bh);
                return -EIO;
        }
        mark_buffer_dirty(bh);
        return 0;
}

int nilfs_init_gcinode(struct inode *inode)
{
        struct nilfs_inode_info *ii = NILFS_I(inode);

        inode->i_mode = S_IFREG;
        mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
        inode->i_mapping->a_ops = &nilfs_buffer_cache_aops;

        ii->i_flags = 0;
        nilfs_bmap_init_gc(ii->i_bmap);

        return nilfs_attach_btree_node_cache(inode);
}

/**
 * nilfs_remove_all_gcinodes() - remove all unprocessed gc inodes
 * @nilfs: NILFS filesystem instance
 */
void nilfs_remove_all_gcinodes(struct the_nilfs *nilfs)
{
        struct list_head *head = &nilfs->ns_gc_inodes;
        struct nilfs_inode_info *ii;

        while (!list_empty(head)) {
                ii = list_first_entry(head, struct nilfs_inode_info, i_dirty);
                list_del_init(&ii->i_dirty);
                truncate_inode_pages(&ii->vfs_inode.i_data, 0);
                nilfs_btnode_cache_clear(ii->i_assoc_inode->i_mapping);
                iput(&ii->vfs_inode);
        }
}