text: /*	$OpenBSD: ffs_subr.c,v 1.15 2004/01/20 03:44:06 tedu Exp $	*/
  /*	$NetBSD: ffs_subr.c,v 1.6 1996/03/17 02:16:23 christos Exp $	*/
  
  /*
   * Copyright (c) 1982, 1986, 1989, 1993
   *	The Regents of the University of California.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   *	@(#)ffs_subr.c	8.2 (Berkeley) 9/21/93
   */
  
  #include <sys/param.h>
  #include <ufs/ffs/fs.h>
  
  #ifdef _KERNEL
  #include <sys/systm.h>
  #include <sys/vnode.h>
  #include <sys/mount.h>
  #include <sys/buf.h>
  
  #include <ufs/ufs/extattr.h>
  #include <ufs/ufs/quota.h>
  #include <ufs/ufs/inode.h>
  #include <ufs/ufs/ufsmount.h>
  #include <ufs/ufs/ufs_extern.h>
  
  #include <ufs/ffs/ffs_extern.h>
  
  /*
   * Return buffer with the contents of block "offset" from the beginning of
   * directory "ip".  If "res" is non-zero, fill it in with a pointer to the
   * remaining space in the directory.
   */
  int
  ffs_bufatoff(struct inode *ip, off_t offset, char **res, struct buf **bpp)
  {
  	struct fs *fs;
  	struct vnode *vp;
  	struct buf *bp;
  	daddr_t lbn;
  	int bsize, error;
  
  	vp = ITOV(ip);
  	fs = ip->i_fs;
  	lbn = lblkno(fs, offset);
  	bsize = blksize(fs, ip, lbn);
  
  	*bpp = NULL;
  	if ((error = bread(vp, lbn, bsize, NOCRED, &bp)) != 0) {
  		brelse(bp);
  		return (error);
  	}
  	if (res)
  		*res = (char *)bp->b_data + blkoff(fs, offset);
  	*bpp = bp;
  	return (0);
  }
  #else
  /* Prototypes for userland */
  void	ffs_fragacct(struct fs *, int, int32_t[], int);
  int	ffs_isfreeblock(struct fs *, unsigned char *, daddr_t);
  int	ffs_isblock(struct fs *, unsigned char *, daddr_t);
  void	ffs_clrblock(struct fs *, u_char *, daddr_t);
  void	ffs_setblock(struct fs *, unsigned char *, daddr_t);
  __dead void panic(const char *, ...);
  #endif
  
  /*
   * Update the frsum fields to reflect addition or deletion
   * of some frags.
   */
  void
  ffs_fragacct(fs, fragmap, fraglist, cnt)
  	struct fs *fs;
  	int fragmap;
  	int32_t fraglist[];
  	int cnt;
  {
  	int inblk;
  	register int field, subfield;
  	register int siz, pos;
  
  	inblk = (int)(fragtbl[fs->fs_frag][fragmap]) << 1;
  	fragmap <<= 1;
  	for (siz = 1; siz < fs->fs_frag; siz++) {
  		if ((inblk & (1 << (siz + (fs->fs_frag % NBBY)))) == 0)
  			continue;
  		field = around[siz];
  		subfield = inside[siz];
  		for (pos = siz; pos <= fs->fs_frag; pos++) {
  			if ((fragmap & field) == subfield) {
  				fraglist[siz] += cnt;
  				pos += siz;
  				field <<= siz;
  				subfield <<= siz;
  			}
  			field <<= 1;
  			subfield <<= 1;
  		}
  	}
  }
  
  #if defined(_KERNEL) && defined(DIAGNOSTIC)
  void
  ffs_checkoverlap(bp, ip)
  	struct buf *bp;
  	struct inode *ip;
  {
  	register struct buf *ebp, *ep;
  	register daddr_t start, last;
  	struct vnode *vp;
  
  	ebp = &buf[nbuf];
  	start = bp->b_blkno;
  	last = start + btodb(bp->b_bcount) - 1;
  	for (ep = buf; ep < ebp; ep++) {
  		if (ep == bp || (ep->b_flags & B_INVAL) ||
  		    ep->b_vp == NULLVP)
  			continue;
  		if (VOP_BMAP(ep->b_vp, (daddr_t)0, &vp, (daddr_t)0, NULL))
  			continue;
  		if (vp != ip->i_devvp)
  			continue;
  		/* look for overlap */
  		if (ep->b_bcount == 0 || ep->b_blkno > last ||
  		    ep->b_blkno + btodb(ep->b_bcount) <= start)
  			continue;
  		vprint("Disk overlap", vp);
  		(void)printf("\tstart %d, end %d overlap start %d, end %ld\n",
  			start, last, ep->b_blkno,
  			ep->b_blkno + btodb(ep->b_bcount) - 1);
  		panic("Disk buffer overlap");
  	}
  }
  #endif /* DIAGNOSTIC */
  
  /*
   * block operations
   *
   * check if a block is available
   */
  int
  ffs_isblock(fs, cp, h)
  	struct fs *fs;
  	unsigned char *cp;
  	daddr_t h;
  {
  	unsigned char mask;
  
  	switch ((int)fs->fs_frag) {
  	case 8:
  		return (cp[h] == 0xff);
  	case 4:
  		mask = 0x0f << ((h & 0x1) << 2);
  		return ((cp[h >> 1] & mask) == mask);
  	case 2:
  		mask = 0x03 << ((h & 0x3) << 1);
  		return ((cp[h >> 2] & mask) == mask);
  	case 1:
  		mask = 0x01 << (h & 0x7);
  		return ((cp[h >> 3] & mask) == mask);
  	default:
  		panic("ffs_isblock");
  	}
  }
  
  /*
   * take a block out of the map
   */
  void
  ffs_clrblock(fs, cp, h)
  	struct fs *fs;
  	u_char *cp;
  	daddr_t h;
  {
  
  	switch ((int)fs->fs_frag) {
  	case 8:
  		cp[h] = 0;
  		return;
  	case 4:
  		cp[h >> 1] &= ~(0x0f << ((h & 0x1) << 2));
  		return;
  	case 2:
  		cp[h >> 2] &= ~(0x03 << ((h & 0x3) << 1));
  		return;
  	case 1:
  		cp[h >> 3] &= ~(0x01 << (h & 0x7));
  		return;
  	default:
  		panic("ffs_clrblock");
  	}
  }
  
  /*
   * put a block into the map
   */
  void
  ffs_setblock(fs, cp, h)
  	struct fs *fs;
  	unsigned char *cp;
  	daddr_t h;
  {
  
  	switch ((int)fs->fs_frag) {
  
  	case 8:
  		cp[h] = 0xff;
  		return;
  	case 4:
  		cp[h >> 1] |= (0x0f << ((h & 0x1) << 2));
  		return;
  	case 2:
  		cp[h >> 2] |= (0x03 << ((h & 0x3) << 1));
  		return;
  	case 1:
  		cp[h >> 3] |= (0x01 << (h & 0x7));
  		return;
  	default:
  		panic("ffs_setblock");
  	}
  }
  
  
  /*
   * check if a block is free
   */
  int
  ffs_isfreeblock(fs, cp, h)
  	struct fs *fs;
  	unsigned char *cp;
  	daddr_t h;
  {
  
  	switch ((int)fs->fs_frag) {
  	case 8:
  		return (cp[h] == 0);
  	case 4:
  		return ((cp[h >> 1] & (0x0f << ((h & 0x1) << 2))) == 0);
  	case 2:
  		return ((cp[h >> 2] & (0x03 << ((h & 0x3) << 1))) == 0);
  	case 1:
  		return ((cp[h >> 3] & (0x01 << (h & 0x7))) == 0);
  	default:
  		panic("ffs_isfreeblock");
  	}
  }
  