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New functions for pagebuf
xfs_bmap
xfs_iomap_read
works for simple case of generic_file_read

/*
 * Copyright (C) 1999 Silicon Graphics, Inc.  All Rights Reserved.
 * 
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License as published
 * by the Free Software Fondation.
 * 
 * This program is distributed in the hope that it would be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  Further, any license provided herein,
 * whether implied or otherwise, is limited to this program in accordance with
 * the express provisions of the GNU General Public License.  Patent licenses,
 * if any, provided herein do not apply to combinations of this program with
 * other product or programs, or any other product whatsoever.  This program is
 * distributed without any warranty that the program is delivered free of the
 * rightful claim of any third person by way of infringement or the like.  See
 * the GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston MA 02111-1307, USA.
 */
/*
 *  fs/xfs/linux/xfs_lrw.c (Linux Read Write stuff)
 *
 */
#define FSID_T
#include <sys/types.h>
#include <linux/errno.h>
#include "xfs_coda_oops.h"

#include <linux/xfs_to_linux.h>

#undef  NODEV
#include <linux/version.h>
#include <linux/fs.h>
#include <linux/page_buf.h>
#include <linux/linux_to_xfs.h>

#include "xfs_buf.h"
#include <ksys/behavior.h>
#include <sys/vnode.h>
#include <sys/uuid.h>
#include "xfs_macros.h"
#include "xfs_types.h"
#include "xfs_inum.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir.h"
#include "xfs_dir2.h"
#include "xfs_mount.h"
#include "xfs_alloc_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_itable.h"
#include "xfs_btree.h"
#include "xfs_alloc.h"
#include "xfs_bmap.h"
#include "xfs_ialloc.h"
#include "xfs_attr_sf.h"
#include "xfs_dir_sf.h"
#include "xfs_dir2_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode_item.h"
#include "xfs_inode.h"
#include "xfs_error.h"
#include "xfs_bit.h"
#include "xfs_trans_space.h"
#include "xfs_lrw.h"
#include "xfs_quota.h"

ssize_t
xfs_rdwr(
	bhv_desc_t      *bdp,
	struct file	*filp,
	char 		*buf,
	size_t		size,
	loff_t		*offsetp,
	int		read)	/* set if read, otherwise this is write */
{
	ssize_t ret;
	struct xfs_inode *xip;

/* 	printk("ENTER xfs_rdwr %x %d %d\n", (unsigned int)filp, size, read); */

	xip = XFS_BHVTOI(bdp);
	if (XFS_FORCED_SHUTDOWN(xip->i_mount)) {
		ret = -EIO;
		goto out;
	}

	ret = 0;
	if (size == 0) {
		goto out;
	}

	if (read) {
	  ret = pagebuf_generic_file_read(filp, buf, size, offsetp); 
/* 		ret = generic_file_read(filp, buf, size, offsetp); */
	} else {
		/* last zero eof */
		ret = pagebuf_generic_file_write(filp, buf, size, offsetp);
	}
out:
/* 	printk("EXIT xfs_rdwr %d %d %X\n", read, ret, *offsetp); */
	return(ret);
}

ssize_t
xfs_read(
	bhv_desc_t      *bdp,
	struct file	*filp,
	char 		*buf,
	size_t		size,
	loff_t		*offsetp)
{
	return(xfs_rdwr(bdp, filp, buf, size, offsetp, 1));
}

ssize_t
xfs_write(
	bhv_desc_t      *bdp,
	struct file	*filp,
	char		*buf,
	size_t		size,
	loff_t		*offsetp)
{
	return(xfs_rdwr(bdp, filp, buf, size, offsetp, 0));
}

/* this is the same as the irix xfs_bmap from xfs_rw.c 
 * execpt for slight changes to the params
 */
int
xfs_bmap( bhv_desc_t	*bdp,
		  off_t		offset,
		  ssize_t		count,
		  int		flags,
		  pb_bmap_t	*pbmapp,
		  int		*npbmaps)
{
  xfs_inode_t *ip;
  int error;
  int		unlocked;
  int		lockmode;
  
/*   printk("ENTER xfs_bmap\n"); */
  ip = XFS_BHVTOI(bdp);
  ASSERT((ip->i_d.di_mode & FMT) == IFREG);
  ASSERT((flags == XFS_B_READ) || (flags == XFS_B_WRITE));

  if (flags == XFS_B_READ) {
	ASSERT(ismrlocked(&ip->i_iolock, MR_ACCESS | MR_UPDATE) != 0);
	unlocked = 0;
	lockmode = xfs_ilock_map_shared(ip);
	error = xfs_iomap_read(&ip->i_iocore, offset, count,
						   pbmapp, npbmaps, 
						   NULL, &unlocked, lockmode);
	if (!unlocked)
	  xfs_iunlock_map_shared(ip, lockmode);
  } else { /* XFS_B_WRITE */
	ASSERT(ismrlocked(&ip->i_iolock, MR_UPDATE) != 0);
	xfs_ilock(ip, XFS_ILOCK_EXCL);
	ASSERT(ip->i_d.di_size >= (offset + count));
	/* 
	 * Make sure that the dquots are there. This doesn't hold 
	 * the ilock across a disk read.
	 */
	if (XFS_IS_QUOTA_ON(ip->i_mount)) {
	  if (XFS_NOT_DQATTACHED(ip->i_mount, ip)) {
		if (error = xfs_qm_dqattach(ip, XFS_QMOPT_ILOCKED)){
		  xfs_iunlock(ip, XFS_ILOCK_EXCL);
		  return error;
		}
	  }
	}
	error = xfs_iomap_write(&ip->i_iocore, offset, count, 
							pbmapp, npbmaps, 0, NULL);
	xfs_iunlock(ip, XFS_ILOCK_EXCL);
	if (!error)
	  XFS_INODE_CLEAR_READ_AHEAD(&ip->i_iocore);
  }
/*   printk("EXIT xfs_bmap %d\n",error); */
  return error;
}	


int
xfs_iomap_read(
	xfs_iocore_t   *io,
	off_t		    offset,
	size_t		    count,
	pb_bmap_t      *pbmapp,
	int		       *npbmaps,
	struct pm	   *pmp,
	int		       *unlocked,
	unsigned int	lockmode)
{	
  xfs_fileoff_t	offset_fsb;
  xfs_fileoff_t	last_fsb;
  xfs_fileoff_t	max_fsb;
  xfs_fsblock_t	firstblock;
  
  xfs_fsize_t	nisize;
  int		nimaps;
  int		error;
  xfs_mount_t	*mp;
  xfs_bmbt_irec_t	imap[XFS_MAX_RW_NBMAPS];

  ASSERT(ismrlocked(io->io_lock, MR_UPDATE | MR_ACCESS) != 0);
  ASSERT(ismrlocked(io->io_iolock, MR_UPDATE | MR_ACCESS) != 0);
/*   xfs_iomap_enter_trace(XFS_IOMAP_READ_ENTER, io, offset, count); */
  
  mp = io->io_mount;
  nisize = io->io_new_size;
  if (nisize < XFS_SIZE(mp, io)) {
	nisize = XFS_SIZE(mp, io);
  }
  offset_fsb = XFS_B_TO_FSBT(mp, offset);
  nimaps = sizeof(imap) / sizeof(imap[0]);
  last_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)nisize));
  if (offset >= nisize) {
	/*
	 * The VM/chunk code is trying to map a page or part
	 * of a page to be pushed out that is beyond the end
	 * of the file.  We handle these cases separately so
	 * that they do not interfere with the normal path
	 * code.
	 */
	error = xfs_iomap_extra(io, offset, count, pbmapp, npbmaps, pmp);
	return error;
  }
  /*
   * Map out to the maximum possible file size.  This will return
   * an extra hole we don't really care about at the end, but we
   * won't do any read-ahead beyond the EOF anyway.  We do this
   * so that the buffers we create here line up well with those
   * created in xfs_iomap_write() which extend beyond the end of
   * the file.
   */
  max_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_MAX_FILE_OFFSET);
  firstblock = NULLFSBLOCK;
/*   printk("xfs_bmap nimaps %d\n",nimaps); */
  error = XFS_BMAPI(mp, NULL, io, offset_fsb,
					(xfs_filblks_t)(max_fsb - offset_fsb),
					XFS_BMAPI_ENTIRE, &firstblock, 0, imap,
					&nimaps, NULL);
/*   printk("xfs_bmap nimaps %d imaps %d\n",nimaps,imap); */
  if (error) {
	return error;
  }


  { 
	int i;
	xfs_fsblock_t	start_block=0;
	xfs_fsblock_t	ext_offset=0;
/*   printk("xfs_bmap nimaps %d npbmaps %d\n",nimaps,*npbmaps); */
  for (i=0; i < (*npbmaps < nimaps?*npbmaps:nimaps); i++){
#if 0
 	printk("xfs_bmap %lld %lld %lld %d\n",
		   (imap[i]).br_startoff, 
 		   (imap[i]).br_startblock, 
 		   (imap[i]).br_blockcount, 
 		   (imap[i]).br_state); 
#endif
	if ((imap[i]).br_startblock != -1) {
	  (imap[i]).br_startblock = XFS_FSB_TO_DB_IO(io, (imap[i]).br_startblock);
	}
  	if (XFS_FSB_TO_B(mp, pbmapp->pbm_offset + pbmapp->pbm_bsize) >= nisize) {
		pbmapp->pbm_flags |= PBMF_EOF;
	}
	(pbmapp[i]).pbm_offset = offset - XFS_FSB_TO_B(mp, (imap[i]).br_startoff);
	
	/* this may be wrong... need to convert from BB to byte ... so << 9 */
	/* as long as the m_blkbb_log is set correctly in xfs_mount_int this seems to be correct */
	(pbmapp[i]).pbm_bsize = XFS_FSB_TO_BB(mp,(imap[i]).br_blockcount);

	start_block = (imap[i]).br_startblock;
	if (start_block == HOLESTARTBLOCK) {
	  (pbmapp[i]).pbm_bn = -1;
	  (pbmapp[i]).pbm_flags = PBMF_HOLE;
	} else if (start_block == DELAYSTARTBLOCK) {
	  (pbmapp[i]).pbm_bn = -1;
	  (pbmapp[i]).pbm_flags	= PBMF_DELAY;
	} else {
	  (pbmapp[i]).pbm_bn = start_block + ext_offset;
	  (pbmapp[i]).pbm_flags = 0;
	  if ((imap[i]).br_state == XFS_EXT_UNWRITTEN)
		(pbmapp[i]).pbm_flags |= PBMF_UNWRITTEN;
	}
#if 0
	switch((imap[i]).br_state){
	case XFS_EXT_NORM:
/* 	  printk("XFS_EXT_NORM:\n"); */
	  break;
	case XFS_EXT_UNWRITTEN:
/* 	  printk("XFS_EXT_UNWRITTEN:\n"); */
	  break;
	case XFS_EXT_DMAPI_OFFLINE:
/* 	  printk("XFS_EXT_NORM:\n"); */
	  break;
	}
#endif
  }
  *npbmaps = nimaps;
  } /* local variable */
  return error;

}

STATIC int
xfs_iomap_write(
	xfs_iocore_t	*io,
	off_t		     offset,
	size_t		     count,
	pb_bmap_t       *pbmapp,
	int		        *npbmaps,
	int		         ioflag,
	struct pm	    *pmp)
{
  printk("xfs_iomap_write NOT!... getting to it\n");
  return 0;
}



STATIC int					/* error */
_xfs_iomap_extra( xfs_iocore_t	*io,
				 off_t		offset,
				 size_t		count,
				 pb_bmap_t  *pbmapp,
				 int		*npbmaps,
				 struct pm	*pmp)
{
  printk("xfs_iomap_extra NOT!... getting to it\n");
  return 0;
}

STATIC int					/* error */
xfs_iomap_extra(
	xfs_iocore_t	*io,
	off_t		offset,
	size_t		count,
	pb_bmap_t  *pbmapp,
	int		*npbmaps,
	struct pm	*pmp)
{
	xfs_fileoff_t	offset_fsb;
	xfs_fileoff_t	end_fsb;
	xfs_fsize_t	nisize;
	xfs_mount_t	*mp;
	int		nimaps;
	xfs_fsblock_t	firstblock;
	int		error;
	xfs_bmbt_irec_t	imap;

	mp = io->io_mount;
	nisize = io->io_new_size;
	if (nisize < XFS_SIZE(mp, io)) {
		nisize = XFS_SIZE(mp, io);
	}
	offset_fsb = XFS_B_TO_FSBT(mp, offset);

	if (poff(offset) != 0) {
		/*
		 * This is the 'remainder' of a page being mapped out.
		 * Since it is already beyond the EOF, there is no reason
		 * to bother.
		 */
		ASSERT(count < NBPP);
		*npbmaps = 1;
		pbmapp->pbm_flags = PBMF_EOF;
		pbmapp->pbm_bn = -1;
		pbmapp->pbm_offset = XFS_FSB_TO_BB(mp, offset_fsb);
		/*		pbmapp->length = 0; */
		pbmapp->pbm_bsize = 0;
#if 0
		if (io->io_flags & XFS_IOCORE_RT) {
			pbmapp->pbdev = mp->m_rtdev;
		} else {
			pbmapp->pbdev = mp->m_dev;
		}
#endif
	} else {
		/*
		 * A page is being mapped out so that it can be flushed.
		 * The page is beyond the EOF, but we need to return
		 * something to keep the chunk cache happy.
		 */
		ASSERT(count <= NBPP);
		end_fsb = XFS_B_TO_FSB(mp, ((xfs_ufsize_t)(offset + count)));
		nimaps = 1;
		firstblock = NULLFSBLOCK;
		error = XFS_BMAPI(mp, NULL, io, offset_fsb,
				  (xfs_filblks_t)(end_fsb - offset_fsb),
				  0, &firstblock, 0, &imap,
				  &nimaps, NULL);
		if (error) {
			return error;
		}
		ASSERT(nimaps == 1);
		*npbmaps = 1;
        pbmapp->pbm_flags = PBMF_EOF;
		if (imap.br_startblock == HOLESTARTBLOCK) {
			pbmapp->pbm_flags |= PBMF_HOLE;
			pbmapp->pbm_bn = -1;
		} else if (imap.br_startblock == DELAYSTARTBLOCK) {
			pbmapp->pbm_flags |= PBMF_DELAY;
			pbmapp->pbm_bn = -1;
		} else {
			pbmapp->pbm_bn = XFS_FSB_TO_DB_IO(io, imap.br_startblock);
			if (imap.br_state == XFS_EXT_UNWRITTEN)
				pbmapp->pbm_flags |= PBMF_UNWRITTEN;
		}
		pbmapp->pbm_offset = XFS_FSB_TO_BB(mp, offset_fsb);
/* 		pbmapp->pbm_length = XFS_FSB_TO_BB(mp, imap.br_blockcount); */
/* 		ASSERT(pbmapp->pbm_length > 0); */
/*		pbmapp->pbm_bsize = BBTOB(bmapp->length); */
		pbmapp->pbm_bsize = BBTOB(XFS_FSB_TO_BB(mp, imap.br_blockcount));
	    pbmapp->pbm_offset = offset - BBTOOFF(pbmapp->pbm_offset);
		ASSERT(pbmapp->pbm_offset >= 0);
#if 0
 		pbmapp->pbsize = pbmapp->pbm_bsize - pbmapp->pbm_offset; 
 		ASSERT(bmapp->pbsize > 0); 
		bmapp->pmp = pmp;
		if (bmapp->pbsize > count) {
			bmapp->pbsize = count;
		}
		if (io->io_flags & XFS_IOCORE_RT) {
			bmapp->pbdev = mp->m_rtdev;
		} else {
			bmapp->pbdev = mp->m_dev;
		}
#endif
	}
	return 0;
}