/*
 * 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  8.5 (Berkeley) 3/21/95
 * $FreeBSD: src/sys/ufs/ffs/ffs_subr.c,v 1.25 1999/12/29 04:55:04 peter Exp $
 */

#include <sys/param.h>

#ifndef _KERNEL
#include "dinode.h"
#include "fs.h"
extern void panic(const char *, ...) __printflike(1, 2) __dead2;
#else
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/vnode.h>
#include <sys/buf.h>
#include <sys/ucred.h>
#include <sys/mount.h>

#include <sys/buf2.h>

#include "quota.h"
#include "inode.h"
#include "fs.h"
#include "ffs_extern.h"

/*
 * Return buffer with the contents of block "offset" from the beginning of
 * vnode "vp".  If "res" is non-zero, fill it in with a pointer to the
 * remaining space in the vnode.
 */
int
ffs_blkatoff(struct vnode *vp, off_t uoffset, char **res, struct buf **bpp)
{
        struct inode *ip;
        struct fs *fs;
        struct buf *bp;
        ufs_daddr_t lbn;
        int bsize, error;

        ip = VTOI(vp);
        fs = ip->i_fs;
        lbn = lblkno(fs, uoffset);
        bsize = blksize(fs, ip, lbn);

        *bpp = NULL;
        error = bread(vp, lblktodoff(fs, lbn), bsize, &bp);
        if (error) {
                brelse(bp);
                return (error);
        }
        if (res)
                *res = (char *)bp->b_data + blkoff(fs, uoffset);
        *bpp = bp;
        return (0);
}

/*
 * Return buffer with the contents of block "offset" from the beginning of
 * vnode "vp".  If "res" is non-zero, fill it in with a pointer to the
 * remaining space in the vnode.
 *
 * This version includes a read-ahead optimization.
 */
int
ffs_blkatoff_ra(struct vnode *vp, off_t uoffset, char **res, struct buf **bpp,
                int seqcount)
{
        struct inode *ip;
        struct fs *fs;
        struct buf *bp;
        ufs_daddr_t lbn;
        ufs_daddr_t nextlbn;
        off_t base_loffset;
        off_t next_loffset;
        int bsize, error;
        int nextbsize;

        ip = VTOI(vp);
        fs = ip->i_fs;
        lbn = lblkno(fs, uoffset);
        base_loffset = lblktodoff(fs, lbn);
        bsize = blksize(fs, ip, lbn);

        nextlbn = lbn + 1;
        next_loffset = lblktodoff(fs, nextlbn);


        *bpp = NULL;

        if (next_loffset >= ip->i_size) {
                /*
                 * Do not do readahead if this is the last block,
                 * bsize might represent a fragment.
                 */
                error = bread(vp, base_loffset, bsize, &bp);
        } else if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
                /*
                 * Try to cluster if we allowed to.
                 */
                error = cluster_read(vp, (off_t)ip->i_size,
                                     base_loffset, bsize,
                                     bsize, seqcount * MAXBSIZE, &bp);
        } else if (seqcount > 1) {
                /*
                 * Faked read ahead
                 */
                nextbsize = blksize(fs, ip, nextlbn);
                error = breadn(vp, base_loffset, bsize,
                               &next_loffset, &nextbsize, 1, &bp);
        } else {
                /*
                 * Failing all of the above, just read what the
                 * user asked for. Interestingly, the same as
                 * the first option above.
                 */
                error = bread(vp, base_loffset, bsize, &bp);
        }
        if (error) {
                brelse(bp);
                return (error);
        }
        if (res)
                *res = (char *)bp->b_data + (int)(uoffset - base_loffset);
        *bpp = bp;
        return (0);
}

#endif

/*
 * Update the frsum fields to reflect addition or deletion
 * of some frags.
 */
void
ffs_fragacct(struct fs *fs, int fragmap, int32_t fraglist[], int cnt)
{
        int inblk;
        int field, subfield;
        int siz, pos;

        /*
         * inblk represents a bitmap of fragment sizes which may be
         * contained in the data 'fragmap'.  e.g. if a fragment of size
         * 1 is available, bit 0 would be set.  inblk is shifted left
         * by one so we do not have to calculate (1 << (siz - 1)).
         *
         * fragment represents the data pattern we are trying to decipher,
         * we shift it left by one to align it with the 'around' and 'inside'
         * masks.
         *
         * around represents the bits around the subfield and is a mask.
         * inside represents what we must match within the mask, it is
         * basically the mask with the first and last bit set to 0, allowing
         * us to represent a whole fragment.
         *
         * When we find a match we bump our position by the size of the
         * matching fragment, then bump the position again:
         *
         * 010101010 fragmap (shifted left by 1)
         *       111 around mask
         *       010 inside mask
         *      111     (shifted by siz)
         *      010
         *     111      (shifted again)
         *     010
         */
        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;
                }
        }
}

/*
 * block operations
 *
 * check if a block is available
 */
int
ffs_isblock(struct fs *fs, unsigned char *cp, ufs_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");
        }
}

/*
 * check if a block is free
 */
int
ffs_isfreeblock(struct fs *fs, unsigned char *cp, ufs_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");
        }
}

/*
 * take a block out of the map
 */
void
ffs_clrblock(struct fs *fs, u_char *cp, ufs_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(struct fs *fs, unsigned char *cp, ufs_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");
        }
}