/*
   *  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
  ", 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
  ");
  	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
  ", bitmap_nr);
  
  	uspi = sbi->s_uspi;
  	if (sbi->s_cgno[bitmap_nr] == UFS_CGNO_EMPTY) {
  		UFSD("EXIT
  ");
  		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
  ");
  }
  
  /*
   * 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
  ", 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
  ");
  		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)
  ");
  				return NULL;
  			}
  			else {
  				UFSD("EXIT
  ");
  				return sbi->s_ucpi[cgno];
  			}
  		} else {
  			ufs_read_cylinder (sb, cgno, cgno);
  			UFSD("EXIT
  ");
  			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
  ");
  	return sbi->s_ucpi[0];
  }