/*
 * dat.c - NILFS disk address translation.
 *
 * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * Written by Koji Sato.
 */

#include <linux/types.h>
#include <linux/buffer_head.h>
#include <linux/string.h>
#include <linux/errno.h>
#include "nilfs.h"
#include "mdt.h"
#include "alloc.h"
#include "dat.h"


#define NILFS_CNO_MIN   ((__u64)1)
#define NILFS_CNO_MAX   (~(__u64)0)

/**
 * struct nilfs_dat_info - on-memory private data of DAT file
 * @mi: on-memory private data of metadata file
 * @palloc_cache: persistent object allocator cache of DAT file
 * @shadow: shadow map of DAT file
 */
struct nilfs_dat_info {
        struct nilfs_mdt_info mi;
        struct nilfs_palloc_cache palloc_cache;
        struct nilfs_shadow_map shadow;
};

static inline struct nilfs_dat_info *NILFS_DAT_I(struct inode *dat)
{
        return (struct nilfs_dat_info *)NILFS_MDT(dat);
}

static int nilfs_dat_prepare_entry(struct inode *dat,
                                   struct nilfs_palloc_req *req, int create)
{
        return nilfs_palloc_get_entry_block(dat, req->pr_entry_nr,
                                            create, &req->pr_entry_bh);
}

static void nilfs_dat_commit_entry(struct inode *dat,
                                   struct nilfs_palloc_req *req)
{
        mark_buffer_dirty(req->pr_entry_bh);
        nilfs_mdt_mark_dirty(dat);
        brelse(req->pr_entry_bh);
}

static void nilfs_dat_abort_entry(struct inode *dat,
                                  struct nilfs_palloc_req *req)
{
        brelse(req->pr_entry_bh);
}

int nilfs_dat_prepare_alloc(struct inode *dat, struct nilfs_palloc_req *req)
{
        int ret;

        ret = nilfs_palloc_prepare_alloc_entry(dat, req);
        if (ret < 0)
                return ret;

        ret = nilfs_dat_prepare_entry(dat, req, 1);
        if (ret < 0)
                nilfs_palloc_abort_alloc_entry(dat, req);

        return ret;
}

void nilfs_dat_commit_alloc(struct inode *dat, struct nilfs_palloc_req *req)
{
        struct nilfs_dat_entry *entry;
        void *kaddr;

        kaddr = kmap_atomic(req->pr_entry_bh->b_page);
        entry = nilfs_palloc_block_get_entry(dat, req->pr_entry_nr,
                                             req->pr_entry_bh, kaddr);
        entry->de_start = cpu_to_le64(NILFS_CNO_MIN);
        entry->de_end = cpu_to_le64(NILFS_CNO_MAX);
        entry->de_blocknr = cpu_to_le64(0);
        kunmap_atomic(kaddr);

        nilfs_palloc_commit_alloc_entry(dat, req);
        nilfs_dat_commit_entry(dat, req);
}

void nilfs_dat_abort_alloc(struct inode *dat, struct nilfs_palloc_req *req)
{
        nilfs_dat_abort_entry(dat, req);
        nilfs_palloc_abort_alloc_entry(dat, req);
}

static void nilfs_dat_commit_free(struct inode *dat,
                                  struct nilfs_palloc_req *req)
{
        struct nilfs_dat_entry *entry;
        void *kaddr;

        kaddr = kmap_atomic(req->pr_entry_bh->b_page);
        entry = nilfs_palloc_block_get_entry(dat, req->pr_entry_nr,
                                             req->pr_entry_bh, kaddr);
        entry->de_start = cpu_to_le64(NILFS_CNO_MIN);
        entry->de_end = cpu_to_le64(NILFS_CNO_MIN);
        entry->de_blocknr = cpu_to_le64(0);
        kunmap_atomic(kaddr);

        nilfs_dat_commit_entry(dat, req);
        nilfs_palloc_commit_free_entry(dat, req);
}

int nilfs_dat_prepare_start(struct inode *dat, struct nilfs_palloc_req *req)
{
        int ret;

        ret = nilfs_dat_prepare_entry(dat, req, 0);
        WARN_ON(ret == -ENOENT);
        return ret;
}

void nilfs_dat_commit_start(struct inode *dat, struct nilfs_palloc_req *req,
                            sector_t blocknr)
{
        struct nilfs_dat_entry *entry;
        void *kaddr;

        kaddr = kmap_atomic(req->pr_entry_bh->b_page);
        entry = nilfs_palloc_block_get_entry(dat, req->pr_entry_nr,
                                             req->pr_entry_bh, kaddr);
        entry->de_start = cpu_to_le64(nilfs_mdt_cno(dat));
        entry->de_blocknr = cpu_to_le64(blocknr);
        kunmap_atomic(kaddr);

        nilfs_dat_commit_entry(dat, req);
}

int nilfs_dat_prepare_end(struct inode *dat, struct nilfs_palloc_req *req)
{
        struct nilfs_dat_entry *entry;
        sector_t blocknr;
        void *kaddr;
        int ret;

        ret = nilfs_dat_prepare_entry(dat, req, 0);
        if (ret < 0) {
                WARN_ON(ret == -ENOENT);
                return ret;
        }

        kaddr = kmap_atomic(req->pr_entry_bh->b_page);
        entry = nilfs_palloc_block_get_entry(dat, req->pr_entry_nr,
                                             req->pr_entry_bh, kaddr);
        blocknr = le64_to_cpu(entry->de_blocknr);
        kunmap_atomic(kaddr);

        if (blocknr == 0) {
                ret = nilfs_palloc_prepare_free_entry(dat, req);
                if (ret < 0) {
                        nilfs_dat_abort_entry(dat, req);
                        return ret;
                }
        }

        return 0;
}

void nilfs_dat_commit_end(struct inode *dat, struct nilfs_palloc_req *req,
                          int dead)
{
        struct nilfs_dat_entry *entry;
        __u64 start, end;
        sector_t blocknr;
        void *kaddr;

        kaddr = kmap_atomic(req->pr_entry_bh->b_page);
        entry = nilfs_palloc_block_get_entry(dat, req->pr_entry_nr,
                                             req->pr_entry_bh, kaddr);
        end = start = le64_to_cpu(entry->de_start);
        if (!dead) {
                end = nilfs_mdt_cno(dat);
                WARN_ON(start > end);
        }
        entry->de_end = cpu_to_le64(end);
        blocknr = le64_to_cpu(entry->de_blocknr);
        kunmap_atomic(kaddr);

        if (blocknr == 0)
                nilfs_dat_commit_free(dat, req);
        else
                nilfs_dat_commit_entry(dat, req);
}

void nilfs_dat_abort_end(struct inode *dat, struct nilfs_palloc_req *req)
{
        struct nilfs_dat_entry *entry;
        __u64 start;
        sector_t blocknr;
        void *kaddr;

        kaddr = kmap_atomic(req->pr_entry_bh->b_page);
        entry = nilfs_palloc_block_get_entry(dat, req->pr_entry_nr,
                                             req->pr_entry_bh, kaddr);
        start = le64_to_cpu(entry->de_start);
        blocknr = le64_to_cpu(entry->de_blocknr);
        kunmap_atomic(kaddr);

        if (start == nilfs_mdt_cno(dat) && blocknr == 0)
                nilfs_palloc_abort_free_entry(dat, req);
        nilfs_dat_abort_entry(dat, req);
}

int nilfs_dat_prepare_update(struct inode *dat,
                             struct nilfs_palloc_req *oldreq,
                             struct nilfs_palloc_req *newreq)
{
        int ret;

        ret = nilfs_dat_prepare_end(dat, oldreq);
        if (!ret) {
                ret = nilfs_dat_prepare_alloc(dat, newreq);
                if (ret < 0)
                        nilfs_dat_abort_end(dat, oldreq);
        }
        return ret;
}

void nilfs_dat_commit_update(struct inode *dat,
                             struct nilfs_palloc_req *oldreq,
                             struct nilfs_palloc_req *newreq, int dead)
{
        nilfs_dat_commit_end(dat, oldreq, dead);
        nilfs_dat_commit_alloc(dat, newreq);
}

void nilfs_dat_abort_update(struct inode *dat,
                            struct nilfs_palloc_req *oldreq,
                            struct nilfs_palloc_req *newreq)
{
        nilfs_dat_abort_end(dat, oldreq);
        nilfs_dat_abort_alloc(dat, newreq);
}

/**
 * nilfs_dat_mark_dirty -
 * @dat: DAT file inode
 * @vblocknr: virtual block number
 *
 * Description:
 *
 * Return Value: On success, 0 is returned. On error, one of the following
 * negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 */
int nilfs_dat_mark_dirty(struct inode *dat, __u64 vblocknr)
{
        struct nilfs_palloc_req req;
        int ret;

        req.pr_entry_nr = vblocknr;
        ret = nilfs_dat_prepare_entry(dat, &req, 0);
        if (ret == 0)
                nilfs_dat_commit_entry(dat, &req);
        return ret;
}

/**
 * nilfs_dat_freev - free virtual block numbers
 * @dat: DAT file inode
 * @vblocknrs: array of virtual block numbers
 * @nitems: number of virtual block numbers
 *
 * Description: nilfs_dat_freev() frees the virtual block numbers specified by
 * @vblocknrs and @nitems.
 *
 * Return Value: On success, 0 is returned. On error, one of the following
 * negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 *
 * %-ENOENT - The virtual block number have not been allocated.
 */
int nilfs_dat_freev(struct inode *dat, __u64 *vblocknrs, size_t nitems)
{
        return nilfs_palloc_freev(dat, vblocknrs, nitems);
}

/**
 * nilfs_dat_move - change a block number
 * @dat: DAT file inode
 * @vblocknr: virtual block number
 * @blocknr: block number
 *
 * Description: nilfs_dat_move() changes the block number associated with
 * @vblocknr to @blocknr.
 *
 * Return Value: On success, 0 is returned. On error, one of the following
 * negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 */
int nilfs_dat_move(struct inode *dat, __u64 vblocknr, sector_t blocknr)
{
        struct buffer_head *entry_bh;
        struct nilfs_dat_entry *entry;
        void *kaddr;
        int ret;

        ret = nilfs_palloc_get_entry_block(dat, vblocknr, 0, &entry_bh);
        if (ret < 0)
                return ret;

        /*
         * The given disk block number (blocknr) is not yet written to
         * the device at this point.
         *
         * To prevent nilfs_dat_translate() from returning the
         * uncommitted block number, this makes a copy of the entry
         * buffer and redirects nilfs_dat_translate() to the copy.
         */
        if (!buffer_nilfs_redirected(entry_bh)) {
                ret = nilfs_mdt_freeze_buffer(dat, entry_bh);
                if (ret) {
                        brelse(entry_bh);
                        return ret;
                }
        }

        kaddr = kmap_atomic(entry_bh->b_page);
        entry = nilfs_palloc_block_get_entry(dat, vblocknr, entry_bh, kaddr);
        if (unlikely(entry->de_blocknr == cpu_to_le64(0))) {
                nilfs_msg(dat->i_sb, KERN_CRIT,
                          "%s: invalid vblocknr = %llu, [%llu, %llu)",
                          __func__, (unsigned long long)vblocknr,
                          (unsigned long long)le64_to_cpu(entry->de_start),
                          (unsigned long long)le64_to_cpu(entry->de_end));
                kunmap_atomic(kaddr);
                brelse(entry_bh);
                return -EINVAL;
        }
        WARN_ON(blocknr == 0);
        entry->de_blocknr = cpu_to_le64(blocknr);
        kunmap_atomic(kaddr);

        mark_buffer_dirty(entry_bh);
        nilfs_mdt_mark_dirty(dat);

        brelse(entry_bh);

        return 0;
}

/**
 * nilfs_dat_translate - translate a virtual block number to a block number
 * @dat: DAT file inode
 * @vblocknr: virtual block number
 * @blocknrp: pointer to a block number
 *
 * Description: nilfs_dat_translate() maps the virtual block number @vblocknr
 * to the corresponding block number.
 *
 * Return Value: On success, 0 is returned and the block number associated
 * with @vblocknr is stored in the place pointed by @blocknrp. On error, one
 * of the following negative error codes is returned.
 *
 * %-EIO - I/O error.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 *
 * %-ENOENT - A block number associated with @vblocknr does not exist.
 */
int nilfs_dat_translate(struct inode *dat, __u64 vblocknr, sector_t *blocknrp)
{
        struct buffer_head *entry_bh, *bh;
        struct nilfs_dat_entry *entry;
        sector_t blocknr;
        void *kaddr;
        int ret;

        ret = nilfs_palloc_get_entry_block(dat, vblocknr, 0, &entry_bh);
        if (ret < 0)
                return ret;

        if (!nilfs_doing_gc() && buffer_nilfs_redirected(entry_bh)) {
                bh = nilfs_mdt_get_frozen_buffer(dat, entry_bh);
                if (bh) {
                        WARN_ON(!buffer_uptodate(bh));
                        brelse(entry_bh);
                        entry_bh = bh;
                }
        }

        kaddr = kmap_atomic(entry_bh->b_page);
        entry = nilfs_palloc_block_get_entry(dat, vblocknr, entry_bh, kaddr);
        blocknr = le64_to_cpu(entry->de_blocknr);
        if (blocknr == 0) {
                ret = -ENOENT;
                goto out;
        }
        *blocknrp = blocknr;

 out:
        kunmap_atomic(kaddr);
        brelse(entry_bh);
        return ret;
}

ssize_t nilfs_dat_get_vinfo(struct inode *dat, void *buf, unsigned int visz,
                            size_t nvi)
{
        struct buffer_head *entry_bh;
        struct nilfs_dat_entry *entry;
        struct nilfs_vinfo *vinfo = buf;
        __u64 first, last;
        void *kaddr;
        unsigned long entries_per_block = NILFS_MDT(dat)->mi_entries_per_block;
        int i, j, n, ret;

        for (i = 0; i < nvi; i += n) {
                ret = nilfs_palloc_get_entry_block(dat, vinfo->vi_vblocknr,
                                                   0, &entry_bh);
                if (ret < 0)
                        return ret;
                kaddr = kmap_atomic(entry_bh->b_page);
                /* last virtual block number in this block */
                first = vinfo->vi_vblocknr;
                do_div(first, entries_per_block);
                first *= entries_per_block;
                last = first + entries_per_block - 1;
                for (j = i, n = 0;
                     j < nvi && vinfo->vi_vblocknr >= first &&
                             vinfo->vi_vblocknr <= last;
                     j++, n++, vinfo = (void *)vinfo + visz) {
                        entry = nilfs_palloc_block_get_entry(
                                dat, vinfo->vi_vblocknr, entry_bh, kaddr);
                        vinfo->vi_start = le64_to_cpu(entry->de_start);
                        vinfo->vi_end = le64_to_cpu(entry->de_end);
                        vinfo->vi_blocknr = le64_to_cpu(entry->de_blocknr);
                }
                kunmap_atomic(kaddr);
                brelse(entry_bh);
        }

        return nvi;
}

/**
 * nilfs_dat_read - read or get dat inode
 * @sb: super block instance
 * @entry_size: size of a dat entry
 * @raw_inode: on-disk dat inode
 * @inodep: buffer to store the inode
 */
int nilfs_dat_read(struct super_block *sb, size_t entry_size,
                   struct nilfs_inode *raw_inode, struct inode **inodep)
{
        static struct lock_class_key dat_lock_key;
        struct inode *dat;
        struct nilfs_dat_info *di;
        int err;

        if (entry_size > sb->s_blocksize) {
                nilfs_msg(sb, KERN_ERR, "too large DAT entry size: %zu bytes",
                          entry_size);
                return -EINVAL;
        } else if (entry_size < NILFS_MIN_DAT_ENTRY_SIZE) {
                nilfs_msg(sb, KERN_ERR, "too small DAT entry size: %zu bytes",
                          entry_size);
                return -EINVAL;
        }

        dat = nilfs_iget_locked(sb, NULL, NILFS_DAT_INO);
        if (unlikely(!dat))
                return -ENOMEM;
        if (!(dat->i_state & I_NEW))
                goto out;

        err = nilfs_mdt_init(dat, NILFS_MDT_GFP, sizeof(*di));
        if (err)
                goto failed;

        err = nilfs_palloc_init_blockgroup(dat, entry_size);
        if (err)
                goto failed;

        di = NILFS_DAT_I(dat);
        lockdep_set_class(&di->mi.mi_sem, &dat_lock_key);
        nilfs_palloc_setup_cache(dat, &di->palloc_cache);
        nilfs_mdt_setup_shadow_map(dat, &di->shadow);

        err = nilfs_read_inode_common(dat, raw_inode);
        if (err)
                goto failed;

        unlock_new_inode(dat);
 out:
        *inodep = dat;
        return 0;
 failed:
        iget_failed(dat);
        return err;
}