/*
   md.c : Multiple Devices driver for Linux
          Copyright (C) 1994-96 Marc ZYNGIER
	  <zyngier@ufr-info-p7.ibp.fr> or
	  <maz@gloups.fdn.fr>

   A lot of inspiration came from hd.c ...

   kerneld support by Boris Tobotras <boris@xtalk.msk.su>

   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, or (at your option)
   any later version.
   
   You should have received a copy of the GNU General Public License
   (for example /usr/src/linux/COPYING); if not, write to the Free
   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  
*/

#include <linux/config.h>
#include <linux/module.h>
#include <linux/version.h>
#include <linux/malloc.h>
#include <linux/mm.h>
#include <linux/md.h>
#include <linux/hdreg.h>
#include <linux/stat.h>
#include <linux/fs.h>
#include <linux/proc_fs.h>
#include <linux/blkdev.h>
#include <linux/genhd.h>
#ifdef CONFIG_KERNELD
#include <linux/kerneld.h>
#endif
#include <linux/errno.h>

#define MAJOR_NR MD_MAJOR
#define MD_DRIVER

#include <linux/blk.h>

static struct hd_struct md_hd_struct[MAX_MD_DEV];
static int md_blocksizes[MAX_MD_DEV];

int md_size[MAX_MD_DEV]={0, };

static void md_geninit (struct gendisk *);

static struct gendisk md_gendisk=
{
  MD_MAJOR,
  "md",
  0,
  1,
  MAX_MD_DEV,
  md_geninit,
  md_hd_struct,
  md_size,
  MAX_MD_DEV,
  NULL,
  NULL
};

static struct md_personality *pers[MAX_PERSONALITY]={NULL, };

struct md_dev md_dev[MAX_MD_DEV];

static struct gendisk *find_gendisk (kdev_t dev)
{
  struct gendisk *tmp=gendisk_head;

  while (tmp != NULL)
  {
    if (tmp->major==MAJOR(dev))
      return (tmp);
    
    tmp=tmp->next;
  }

  return (NULL);
}


char *partition_name (kdev_t dev)
{
  static char name[40];		/* This should be long
				   enough for a device name ! */
  struct gendisk *hd = find_gendisk (dev);

  if (!hd)
  {
    printk ("No gendisk entry for dev %s\n", kdevname(dev));
    sprintf (name, "dev %s", kdevname(dev));
    return (name);
  }

  return disk_name (hd, MINOR(dev), name);  /* routine in genhd.c */
}


static void set_ra (void)
{
  int i, j, minra=INT_MAX;

  for (i=0; i<MAX_MD_DEV; i++)
  {
    if (!md_dev[i].pers)
      continue;
    
    for (j=0; j<md_dev[i].nb_dev; j++)
      if (read_ahead[MAJOR(md_dev[i].devices[j].dev)]<minra)
	minra=read_ahead[MAJOR(md_dev[i].devices[j].dev)];
  }
  
  read_ahead[MD_MAJOR]=minra;
}


static int do_md_run (int minor, int repart)
{
  int pnum, i, min, current_ra, err;
  
  if (!md_dev[minor].nb_dev)
    return -EINVAL;
  
  if (md_dev[minor].pers)
    return -EBUSY;
  
  md_dev[minor].repartition=repart;
  
  if ((pnum=PERSONALITY(md_dev+minor) >> (PERSONALITY_SHIFT))
      >= MAX_PERSONALITY)
    return -EINVAL;
  
  if (!pers[pnum])
  {
#ifdef CONFIG_KERNELD
    char module_name[80];
    sprintf (module_name, "md-personality-%d", pnum);
    request_module (module_name);
    if (!pers[pnum])
#endif
      return -EINVAL;
  }
  
  min=1 << FACTOR_SHIFT(FACTOR((md_dev+minor)));
  
  for (i=0; i<md_dev[minor].nb_dev; i++)
    if (md_dev[minor].devices[i].size<min)
    {
      printk ("Dev %s smaller than %dk, cannot shrink\n",
	      partition_name (md_dev[minor].devices[i].dev), min);
      return -EINVAL;
    }
  
  /* Resize devices according to the factor. It is used to align
     partitions size on a given chunk size. */
  md_size[minor]=0;
  
  for (i=0; i<md_dev[minor].nb_dev; i++)
  {
    md_dev[minor].devices[i].size &= ~(min - 1);
    md_size[minor] += md_dev[minor].devices[i].size;
    md_dev[minor].devices[i].offset=i ? (md_dev[minor].devices[i-1].offset + md_dev[minor].devices[i-1].size) : 0;
  }

  md_dev[minor].pers=pers[pnum];
  
  if ((err=md_dev[minor].pers->run (minor, md_dev+minor)))
  {
    md_dev[minor].pers=NULL;
    return (err);
  }
  
  /* FIXME : We assume here we have blocks
     that are twice as large as sectors.
     THIS MAY NOT BE TRUE !!! */
  md_hd_struct[minor].start_sect=0;
  md_hd_struct[minor].nr_sects=md_size[minor]<<1;
  
  /* It would be better to have a per-md-dev read_ahead. Currently,
     we only use the smallest read_ahead among md-attached devices */
  
  current_ra=read_ahead[MD_MAJOR];
  
  for (i=0; i<md_dev[minor].nb_dev; i++)
    if (current_ra>read_ahead[MAJOR(md_dev[minor].devices[i].dev)])
      current_ra=read_ahead[MAJOR(md_dev[minor].devices[i].dev)];
  
  read_ahead[MD_MAJOR]=current_ra;
  
  printk ("START_DEV md%x %s\n", minor, md_dev[minor].pers->name);
  return (0);
}


static int do_md_stop (int minor, struct inode *inode)
{
  int i;
  
  if (inode->i_count>1 || md_dev[minor].busy>1) /* ioctl : one open channel */
  {
    printk ("STOP_MD md%x failed : i_count=%d, busy=%d\n", minor, inode->i_count, md_dev[minor].busy);
    return -EBUSY;
  }
  
  if (md_dev[minor].pers)
  {
    /*  The device won't exist anymore -> flush it now */
    fsync_dev (inode->i_rdev);
    invalidate_buffers (inode->i_rdev);
    md_dev[minor].pers->stop (minor, md_dev+minor);
  }
  
  /* Remove locks. */
  for (i=0; i<md_dev[minor].nb_dev; i++)
    clear_inode (md_dev[minor].devices[i].inode);
  
  md_dev[minor].nb_dev=md_size[minor]=0;
  md_hd_struct[minor].nr_sects=0;
  md_dev[minor].pers=NULL;
  
  set_ra ();			/* calculate new read_ahead */
  
  printk ("STOP_DEV md%x\n", minor);
  return (0);
}


static int do_md_add (int minor, kdev_t dev)
{
  struct gendisk *gen_real;
  int i;
  
  if (MAJOR(dev)==MD_MAJOR || md_dev[minor].nb_dev==MAX_REAL)
    return -EINVAL;
  
  if (!fs_may_mount (dev) || md_dev[minor].pers)
    return -EBUSY;
  
  if (!(gen_real=find_gendisk (dev)))
    return -ENOENT;
  
  i=md_dev[minor].nb_dev++;
  md_dev[minor].devices[i].dev=dev;
  
  /* Lock the device by inserting a dummy inode. This doesn't
     smell very good, but I need to be consistent with the
     mount stuff, specially with fs_may_mount. If someone have
     a better idea, please help ! */
  
  md_dev[minor].devices[i].inode=get_empty_inode ();
  md_dev[minor].devices[i].inode->i_dev=dev; /* don't care about
						other fields */
  insert_inode_hash (md_dev[minor].devices[i].inode);
  
  /* Sizes are now rounded at run time */
  
  md_dev[minor].devices[i].size=gen_real->sizes[MINOR(dev)];

  printk ("REGISTER_DEV %s to md%x done\n", partition_name(dev), minor);
  return (0);
}


static int md_ioctl (struct inode *inode, struct file *file,
                     unsigned int cmd, unsigned long arg)
{
  int minor, err;
  struct hd_geometry *loc = (struct hd_geometry *) arg;

  if (!suser())
    return -EACCES;

  if (((minor=MINOR(inode->i_rdev)) & 0x80) &&
      (minor & 0x7f) < MAX_PERSONALITY &&
      pers[minor & 0x7f] &&
      pers[minor & 0x7f]->ioctl)
    return (pers[minor & 0x7f]->ioctl (inode, file, cmd, arg));
  
  if (minor >= MAX_MD_DEV)
    return -EINVAL;

  switch (cmd)
  {
    case REGISTER_DEV:
      return do_md_add (minor, to_kdev_t ((dev_t) arg));

    case START_MD:
      return do_md_run (minor, (int) arg);

    case STOP_MD:
      return do_md_stop (minor, inode);
      
    case BLKGETSIZE:   /* Return device size */
    if  (!arg)  return -EINVAL;
    err=verify_area (VERIFY_WRITE, (long *) arg, sizeof(long));
    if (err)
      return err;
    put_user (md_hd_struct[MINOR(inode->i_rdev)].nr_sects, (long *) arg);
    break;

    case BLKFLSBUF:
    fsync_dev (inode->i_rdev);
    invalidate_buffers (inode->i_rdev);
    break;

    case BLKRASET:
    if (arg > 0xff)
      return -EINVAL;
    read_ahead[MAJOR(inode->i_rdev)] = arg;
    return 0;
    
    case BLKRAGET:
    if  (!arg)  return -EINVAL;
    err=verify_area (VERIFY_WRITE, (long *) arg, sizeof(long));
    if (err)
      return err;
    put_user (read_ahead[MAJOR(inode->i_rdev)], (long *) arg);
    break;

    /* We have a problem here : there is no easy way to give a CHS
       virtual geometry. We currently pretend that we have a 2 heads
       4 sectors (with a BIG number of cylinders...). This drives dosfs
       just mad... ;-) */
    
    case HDIO_GETGEO:
    if (!loc)  return -EINVAL;
    err = verify_area(VERIFY_WRITE, loc, sizeof(*loc));
    if (err)
      return err;
    put_user (2, (char *) &loc->heads);
    put_user (4, (char *) &loc->sectors);
    put_user (md_hd_struct[minor].nr_sects/8, (short *) &loc->cylinders);
    put_user (md_hd_struct[MINOR(inode->i_rdev)].start_sect,
		(long *) &loc->start);
    break;
    
    RO_IOCTLS(inode->i_rdev,arg);
    
    default:
    printk ("Unknown md_ioctl %d\n", cmd);
    return -EINVAL;
  }

  return (0);
}


static int md_open (struct inode *inode, struct file *file)
{
  int minor=MINOR(inode->i_rdev);

  md_dev[minor].busy++;
  return (0);			/* Always succeed */
}


static void md_release (struct inode *inode, struct file *file)
{
  int minor=MINOR(inode->i_rdev);

  sync_dev (inode->i_rdev);
  md_dev[minor].busy--;
}


static int md_read (struct inode *inode, struct file *file,
		    char *buf, int count)
{
  int minor=MINOR(inode->i_rdev);

  if (!md_dev[minor].pers)	/* Check if device is being run */
    return -ENXIO;

  return block_read (inode, file, buf, count);
}

static int md_write (struct inode *inode, struct file *file,
		     const char *buf, int count)
{
  int minor=MINOR(inode->i_rdev);

  if (!md_dev[minor].pers)	/* Check if device is being run */
    return -ENXIO;

  return block_write (inode, file, buf, count);
}

static struct file_operations md_fops=
{
  NULL,
  md_read,
  md_write,
  NULL,
  NULL,
  md_ioctl,
  NULL,
  md_open,
  md_release,
  block_fsync
};

int md_map (int minor, kdev_t *rdev, unsigned long *rsector, unsigned long size)
{
  if ((unsigned int) minor >= MAX_MD_DEV)
  {
    printk ("Bad md device %d\n", minor);
    return (-1);
  }
  
  if (!md_dev[minor].pers)
  {
    printk ("Oops ! md%d not running, giving up !\n", minor);
    return (-1);
  }

  return (md_dev[minor].pers->map(md_dev+minor, rdev, rsector, size));
}
  

static void do_md_request (void)
{
  printk ("Got md request, not good...");
  return;
}  

static struct symbol_table md_symbol_table=
{
#include <linux/symtab_begin.h>

  X(md_size),
  X(register_md_personality),
  X(unregister_md_personality),
  X(partition_name),

#include <linux/symtab_end.h>
};


static void md_geninit (struct gendisk *gdisk)
{
  int i;
  
  for(i=0;i<MAX_MD_DEV;i++)
  {
    md_blocksizes[i] = 1024;
    md_gendisk.part[i].start_sect=-1; /* avoid partition check */
    md_gendisk.part[i].nr_sects=0;
    md_dev[i].pers=NULL;
  }

  blksize_size[MAJOR_NR] = md_blocksizes;
  register_symtab (&md_symbol_table);

  proc_register(&proc_root,
		&(struct proc_dir_entry)
	      {
		PROC_MD, 6, "mdstat",
		S_IFREG | S_IRUGO, 1, 0, 0,
	      });
}


int get_md_status (char *page)
{
  int sz=0, i, j, size;

  sz+=sprintf( page+sz, "Personalities : ");
  for (i=0; i<MAX_PERSONALITY; i++)
    if (pers[i])
      sz+=sprintf (page+sz, "[%d %s] ", i, pers[i]->name);

  page[sz-1]='\n';

  sz+=sprintf (page+sz, "read_ahead ");
  if (read_ahead[MD_MAJOR]==INT_MAX)
    sz+=sprintf (page+sz, "not set\n");
  else
    sz+=sprintf (page+sz, "%d sectors\n", read_ahead[MD_MAJOR]);
  
  for (i=0; i<MAX_MD_DEV; i++)
  {
    sz+=sprintf (page+sz, "md%d : %sactive", i, md_dev[i].pers ? "" : "in");

    if (md_dev[i].pers)
      sz+=sprintf (page+sz, " %s", md_dev[i].pers->name);

    size=0;
    for (j=0; j<md_dev[i].nb_dev; j++)
    {
      sz+=sprintf (page+sz, " %s",
		   partition_name(md_dev[i].devices[j].dev));
      size+=md_dev[i].devices[j].size;
    }
    
    if (md_dev[i].nb_dev)
      sz+=sprintf (page+sz, " %d blocks", size);

    if (!md_dev[i].pers)
    {
      sz+=sprintf (page+sz, "\n");
      continue;
    }

    if (md_dev[i].pers->max_invalid_dev)
      sz+=sprintf (page+sz, " maxfault=%ld", MAX_FAULT(md_dev+i));

    sz+=sprintf (page+sz, " %dk %s\n", 1<<FACTOR_SHIFT(FACTOR(md_dev+i)),
		 md_dev[i].pers == pers[LINEAR>>PERSONALITY_SHIFT] ?
		 "rounding" : "chunks");

    sz+=md_dev[i].pers->status (page+sz, i, md_dev+i);
  }

  return (sz);
}

int register_md_personality (int p_num, struct md_personality *p)
{
  int i=(p_num >> PERSONALITY_SHIFT);

  if (i >= MAX_PERSONALITY)
    return -EINVAL;

  if (pers[i])
    return -EBUSY;
  
  pers[i]=p;
  printk ("%s personality registered\n", p->name);
  return 0;
}

int unregister_md_personality (int p_num)
{
  int i=(p_num >> PERSONALITY_SHIFT);

  if (i >= MAX_PERSONALITY)
    return -EINVAL;

  printk ("%s personality unregistered\n", pers[i]->name);
  pers[i]=NULL;
  return 0;
} 

void linear_init (void);
void raid0_init (void);
void raid1_init (void);
void raid5_init (void);

int md_init (void)
{
  printk ("md driver %s MAX_MD_DEV=%d, MAX_REAL=%d\n", MD_VERSION, MAX_MD_DEV, MAX_REAL);

  if (register_blkdev (MD_MAJOR, "md", &md_fops))
  {
    printk ("Unable to get major %d for md\n", MD_MAJOR);
    return (-1);
  }

  blk_dev[MD_MAJOR].request_fn=DEVICE_REQUEST;
  blk_dev[MD_MAJOR].current_request=NULL;
  read_ahead[MD_MAJOR]=INT_MAX;
  md_gendisk.next=gendisk_head;

  gendisk_head=&md_gendisk;

#ifdef CONFIG_MD_LINEAR
  linear_init ();
#endif
#ifdef CONFIG_MD_STRIPED
  raid0_init ();
#endif
  
  return (0);
}