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/*

 *  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/ufs_fs.h>

#include <linux/time.h>

#include <linux/stat.h>

#include <linux/string.h>

#include <linux/bitops.h>

#include <asm/byteorder.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];

}