/*
 *  linux/fs/ufs/cylinder.c
 *
 * Copyright (C) 1998
 * Daniel Pirkl <daniel.pirkl@email.cz>
 * Charles University, Faculty of Mathematics and Physics
 *
 *  ext2 - inode (block) bitmap caching inspired
 */

#include <linux/fs.h>
#include <linux/time.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/bitops.h>

#include <asm/byteorder.h>

#include "ufs_fs.h"
#include "ufs.h"
#include "swab.h"
#include "util.h"

/*
 * Read cylinder group into cache. The memory space for ufs_cg_private_info
 * structure is already allocated during ufs_read_super.
 */
static void ufs_read_cylinder (struct super_block * sb,
        unsigned cgno, unsigned bitmap_nr)
{
        struct ufs_sb_info * sbi = UFS_SB(sb);
        struct ufs_sb_private_info * uspi;
        struct ufs_cg_private_info * ucpi;
        struct ufs_cylinder_group * ucg;
        unsigned i, j;

        UFSD("ENTER, cgno %u, bitmap_nr %u\n", cgno, bitmap_nr);
        uspi = sbi->s_uspi;
        ucpi = sbi->s_ucpi[bitmap_nr];
        ucg = (struct ufs_cylinder_group *)sbi->s_ucg[cgno]->b_data;

        UCPI_UBH(ucpi)->fragment = ufs_cgcmin(cgno);
        UCPI_UBH(ucpi)->count = uspi->s_cgsize >> sb->s_blocksize_bits;
        /*
         * We have already the first fragment of cylinder group block in buffer
         */
        UCPI_UBH(ucpi)->bh[0] = sbi->s_ucg[cgno];
        for (i = 1; i < UCPI_UBH(ucpi)->count; i++)
                if (!(UCPI_UBH(ucpi)->bh[i] = sb_bread(sb, UCPI_UBH(ucpi)->fragment + i)))
                        goto failed;
        sbi->s_cgno[bitmap_nr] = cgno;
                        
        ucpi->c_cgx     = fs32_to_cpu(sb, ucg->cg_cgx);
        ucpi->c_ncyl    = fs16_to_cpu(sb, ucg->cg_ncyl);
        ucpi->c_niblk   = fs16_to_cpu(sb, ucg->cg_niblk);
        ucpi->c_ndblk   = fs32_to_cpu(sb, ucg->cg_ndblk);
        ucpi->c_rotor   = fs32_to_cpu(sb, ucg->cg_rotor);
        ucpi->c_frotor  = fs32_to_cpu(sb, ucg->cg_frotor);
        ucpi->c_irotor  = fs32_to_cpu(sb, ucg->cg_irotor);
        ucpi->c_btotoff = fs32_to_cpu(sb, ucg->cg_btotoff);
        ucpi->c_boff    = fs32_to_cpu(sb, ucg->cg_boff);
        ucpi->c_iusedoff = fs32_to_cpu(sb, ucg->cg_iusedoff);
        ucpi->c_freeoff = fs32_to_cpu(sb, ucg->cg_freeoff);
        ucpi->c_nextfreeoff = fs32_to_cpu(sb, ucg->cg_nextfreeoff);
        ucpi->c_clustersumoff = fs32_to_cpu(sb, ucg->cg_u.cg_44.cg_clustersumoff);
        ucpi->c_clusteroff = fs32_to_cpu(sb, ucg->cg_u.cg_44.cg_clusteroff);
        ucpi->c_nclusterblks = fs32_to_cpu(sb, ucg->cg_u.cg_44.cg_nclusterblks);
        UFSD("EXIT\n");
        return; 
        
failed:
        for (j = 1; j < i; j++)
                brelse (sbi->s_ucg[j]);
        sbi->s_cgno[bitmap_nr] = UFS_CGNO_EMPTY;
        ufs_error (sb, "ufs_read_cylinder", "can't read cylinder group block %u", cgno);
}

/*
 * Remove cylinder group from cache, doesn't release memory
 * allocated for cylinder group (this is done at ufs_put_super only).
 */
void ufs_put_cylinder (struct super_block * sb, unsigned bitmap_nr)
{
        struct ufs_sb_info * sbi = UFS_SB(sb);
        struct ufs_sb_private_info * uspi; 
        struct ufs_cg_private_info * ucpi;
        struct ufs_cylinder_group * ucg;
        unsigned i;

        UFSD("ENTER, bitmap_nr %u\n", bitmap_nr);

        uspi = sbi->s_uspi;
        if (sbi->s_cgno[bitmap_nr] == UFS_CGNO_EMPTY) {
                UFSD("EXIT\n");
                return;
        }
        ucpi = sbi->s_ucpi[bitmap_nr];
        ucg = ubh_get_ucg(UCPI_UBH(ucpi));

        if (uspi->s_ncg > UFS_MAX_GROUP_LOADED && bitmap_nr >= sbi->s_cg_loaded) {
                ufs_panic (sb, "ufs_put_cylinder", "internal error");
                return;
        }
        /*
         * rotor is not so important data, so we put it to disk 
         * at the end of working with cylinder
         */
        ucg->cg_rotor = cpu_to_fs32(sb, ucpi->c_rotor);
        ucg->cg_frotor = cpu_to_fs32(sb, ucpi->c_frotor);
        ucg->cg_irotor = cpu_to_fs32(sb, ucpi->c_irotor);
        ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
        for (i = 1; i < UCPI_UBH(ucpi)->count; i++) {
                brelse (UCPI_UBH(ucpi)->bh[i]);
        }

        sbi->s_cgno[bitmap_nr] = UFS_CGNO_EMPTY;
        UFSD("EXIT\n");
}

/*
 * Find cylinder group in cache and return it as pointer.
 * If cylinder group is not in cache, we will load it from disk.
 *
 * The cache is managed by LRU algorithm. 
 */
struct ufs_cg_private_info * ufs_load_cylinder (
        struct super_block * sb, unsigned cgno)
{
        struct ufs_sb_info * sbi = UFS_SB(sb);
        struct ufs_sb_private_info * uspi;
        struct ufs_cg_private_info * ucpi;
        unsigned cg, i, j;

        UFSD("ENTER, cgno %u\n", cgno);

        uspi = sbi->s_uspi;
        if (cgno >= uspi->s_ncg) {
                ufs_panic (sb, "ufs_load_cylinder", "internal error, high number of cg");
                return NULL;
        }
        /*
         * Cylinder group number cg it in cache and it was last used
         */
        if (sbi->s_cgno[0] == cgno) {
                UFSD("EXIT\n");
                return sbi->s_ucpi[0];
        }
        /*
         * Number of cylinder groups is not higher than UFS_MAX_GROUP_LOADED
         */
        if (uspi->s_ncg <= UFS_MAX_GROUP_LOADED) {
                if (sbi->s_cgno[cgno] != UFS_CGNO_EMPTY) {
                        if (sbi->s_cgno[cgno] != cgno) {
                                ufs_panic (sb, "ufs_load_cylinder", "internal error, wrong number of cg in cache");
                                UFSD("EXIT (FAILED)\n");
                                return NULL;
                        }
                        else {
                                UFSD("EXIT\n");
                                return sbi->s_ucpi[cgno];
                        }
                } else {
                        ufs_read_cylinder (sb, cgno, cgno);
                        UFSD("EXIT\n");
                        return sbi->s_ucpi[cgno];
                }
        }
        /*
         * Cylinder group number cg is in cache but it was not last used, 
         * we will move to the first position
         */
        for (i = 0; i < sbi->s_cg_loaded && sbi->s_cgno[i] != cgno; i++);
        if (i < sbi->s_cg_loaded && sbi->s_cgno[i] == cgno) {
                cg = sbi->s_cgno[i];
                ucpi = sbi->s_ucpi[i];
                for (j = i; j > 0; j--) {
                        sbi->s_cgno[j] = sbi->s_cgno[j-1];
                        sbi->s_ucpi[j] = sbi->s_ucpi[j-1];
                }
                sbi->s_cgno[0] = cg;
                sbi->s_ucpi[0] = ucpi;
        /*
         * Cylinder group number cg is not in cache, we will read it from disk
         * and put it to the first position
         */
        } else {
                if (sbi->s_cg_loaded < UFS_MAX_GROUP_LOADED)
                        sbi->s_cg_loaded++;
                else
                        ufs_put_cylinder (sb, UFS_MAX_GROUP_LOADED-1);
                ucpi = sbi->s_ucpi[sbi->s_cg_loaded - 1];
                for (j = sbi->s_cg_loaded - 1; j > 0; j--) {
                        sbi->s_cgno[j] = sbi->s_cgno[j-1];
                        sbi->s_ucpi[j] = sbi->s_ucpi[j-1];
                }
                sbi->s_ucpi[0] = ucpi;
                ufs_read_cylinder (sb, cgno, 0);
        }
        UFSD("EXIT\n");
        return sbi->s_ucpi[0];
}