/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1989, 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * 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.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/endian.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/stat.h>

#include <fs/ext2fs/fs.h>
#include <fs/ext2fs/inode.h>
#include <fs/ext2fs/ext2fs.h>
#include <fs/ext2fs/ext2_dinode.h>
#include <fs/ext2fs/ext2_extern.h>
#include <fs/ext2fs/ext2_mount.h>

/*
 * Bmap converts the logical block number of a file to its physical block
 * number on the disk. The conversion is done by using the logical block
 * number to index into the array of block pointers described by the dinode.
 */
int
ext2_bmap(struct vop_bmap_args *ap)
{
        daddr_t blkno;
        int error;

        /*
         * Check for underlying vnode requests and ensure that logical
         * to physical mapping is requested.
         */
        if (ap->a_bop != NULL)
                *ap->a_bop = &VTOI(ap->a_vp)->i_devvp->v_bufobj;
        if (ap->a_bnp == NULL)
                return (0);

        if (VTOI(ap->a_vp)->i_flag & IN_E4EXTENTS)
                error = ext4_bmapext(ap->a_vp, ap->a_bn, &blkno,
                    ap->a_runp, ap->a_runb);
        else
                error = ext2_bmaparray(ap->a_vp, ap->a_bn, &blkno,
                    ap->a_runp, ap->a_runb);
        *ap->a_bnp = blkno;
        return (error);
}

/*
 * Convert the logical block number of a file to its physical block number
 * on the disk within ext4 extents.
 */
int
ext4_bmapext(struct vnode *vp, int32_t bn, int64_t *bnp, int *runp, int *runb)
{
        struct inode *ip;
        struct m_ext2fs *fs;
        struct mount *mp;
        struct ext2mount *ump;
        struct ext4_extent_header *ehp;
        struct ext4_extent *ep;
        struct ext4_extent_path *path = NULL;
        daddr_t lbn;
        int error, depth, maxrun = 0, bsize;

        ip = VTOI(vp);
        fs = ip->i_e2fs;
        mp = vp->v_mount;
        ump = VFSTOEXT2(mp);
        lbn = bn;
        ehp = (struct ext4_extent_header *)ip->i_data;
        depth = le16toh(ehp->eh_depth);
        bsize = EXT2_BLOCK_SIZE(ump->um_e2fs);

        *bnp = -1;
        if (runp != NULL) {
                maxrun = mp->mnt_iosize_max / bsize - 1;
                *runp = 0;
        }
        if (runb != NULL)
                *runb = 0;

        error = ext4_ext_find_extent(ip, lbn, &path);
        if (error)
                return (error);

        ep = path[depth].ep_ext;
        if(ep) {
                if (lbn < le32toh(ep->e_blk)) {
                        if (runp != NULL) {
                                *runp = min(maxrun, le32toh(ep->e_blk) - lbn - 1);
                        }
                } else if (le32toh(ep->e_blk) <= lbn &&
                            lbn < le32toh(ep->e_blk) + le16toh(ep->e_len)) {
                        *bnp = fsbtodb(fs, lbn - le32toh(ep->e_blk) +
                            (le32toh(ep->e_start_lo) |
                            (daddr_t)le16toh(ep->e_start_hi) << 32));
                        if (runp != NULL) {
                                *runp = min(maxrun,
                                    le16toh(ep->e_len) -
                                    (lbn - le32toh(ep->e_blk)) - 1);
                        }
                        if (runb != NULL)
                                *runb = min(maxrun, lbn - le32toh(ep->e_blk));
                } else {
                        if (runb != NULL)
                                *runb = min(maxrun, le32toh(ep->e_blk) + lbn -
                                    le16toh(ep->e_len));
                }
        }

        ext4_ext_path_free(path);

        return (error);
}

static int
readindir(struct vnode *vp, e2fs_lbn_t lbn, e2fs_daddr_t daddr, struct buf **bpp)
{
        struct buf *bp;
        struct mount *mp;
        struct ext2mount *ump;
        int error;

        mp = vp->v_mount;
        ump = VFSTOEXT2(mp);

        bp = getblk(vp, lbn, mp->mnt_stat.f_iosize, 0, 0, 0);
        if ((bp->b_flags & B_CACHE) == 0) {
                KASSERT(daddr != 0,
                    ("readindir: indirect block not in cache"));

                bp->b_blkno = blkptrtodb(ump, daddr);
                bp->b_iocmd = BIO_READ;
                bp->b_flags &= ~B_INVAL;
                bp->b_ioflags &= ~BIO_ERROR;
                vfs_busy_pages(bp, 0);
                bp->b_iooffset = dbtob(bp->b_blkno);
                bstrategy(bp);
#ifdef RACCT
                if (racct_enable) {
                        PROC_LOCK(curproc);
                        racct_add_buf(curproc, bp, 0);
                        PROC_UNLOCK(curproc);
                }
#endif
                curthread->td_ru.ru_inblock++;
                error = bufwait(bp);
                if (error != 0) {
                        brelse(bp);
                        return (error);
                }
        }
        *bpp = bp;
        return (0);
}

/*
 * Indirect blocks are now on the vnode for the file.  They are given negative
 * logical block numbers.  Indirect blocks are addressed by the negative
 * address of the first data block to which they point.  Double indirect blocks
 * are addressed by one less than the address of the first indirect block to
 * which they point.  Triple indirect blocks are addressed by one less than
 * the address of the first double indirect block to which they point.
 *
 * ext2_bmaparray does the bmap conversion, and if requested returns the
 * array of logical blocks which must be traversed to get to a block.
 * Each entry contains the offset into that block that gets you to the
 * next block and the disk address of the block (if it is assigned).
 */

int
ext2_bmaparray(struct vnode *vp, daddr_t bn, daddr_t *bnp, int *runp, int *runb)
{
        struct inode *ip;
        struct buf *bp;
        struct ext2mount *ump;
        struct mount *mp;
        struct indir a[EXT2_NIADDR + 1], *ap;
        daddr_t daddr;
        e2fs_lbn_t metalbn;
        int error, num, maxrun = 0, bsize;
        int *nump;

        ap = NULL;
        ip = VTOI(vp);
        mp = vp->v_mount;
        ump = VFSTOEXT2(mp);

        bsize = EXT2_BLOCK_SIZE(ump->um_e2fs);

        if (runp) {
                maxrun = mp->mnt_iosize_max / bsize - 1;
                *runp = 0;
        }
        if (runb)
                *runb = 0;

        ap = a;
        nump = &num;
        error = ext2_getlbns(vp, bn, ap, nump);
        if (error)
                return (error);

        num = *nump;
        if (num == 0) {
                *bnp = blkptrtodb(ump, ip->i_db[bn]);
                if (*bnp == 0) {
                        *bnp = -1;
                } else if (runp) {
                        daddr_t bnb = bn;

                        for (++bn; bn < EXT2_NDADDR && *runp < maxrun &&
                            is_sequential(ump, ip->i_db[bn - 1], ip->i_db[bn]);
                            ++bn, ++*runp);
                        bn = bnb;
                        if (runb && (bn > 0)) {
                                for (--bn; (bn >= 0) && (*runb < maxrun) &&
                                        is_sequential(ump, ip->i_db[bn],
                                                ip->i_db[bn + 1]);
                                                --bn, ++*runb);
                        }
                }
                return (0);
        }

        /* Get disk address out of indirect block array */
        daddr = ip->i_ib[ap->in_off];

        for (bp = NULL, ++ap; --num; ++ap) {
                /*
                 * Exit the loop if there is no disk address assigned yet and
                 * the indirect block isn't in the cache, or if we were
                 * looking for an indirect block and we've found it.
                 */

                metalbn = ap->in_lbn;
                if ((daddr == 0 && !incore(&vp->v_bufobj, metalbn)) || metalbn == bn)
                        break;
                /*
                 * If we get here, we've either got the block in the cache
                 * or we have a disk address for it, go fetch it.
                 */
                if (bp)
                        bqrelse(bp);
                error = readindir(vp, metalbn, daddr, &bp);
                if (error != 0)
                        return (error);

                daddr = le32toh(((e2fs_daddr_t *)bp->b_data)[ap->in_off]);
                if (num == 1 && daddr && runp) {
                        for (bn = ap->in_off + 1;
                            bn < MNINDIR(ump) && *runp < maxrun &&
                            is_sequential(ump,
                            ((e2fs_daddr_t *)bp->b_data)[bn - 1],
                            ((e2fs_daddr_t *)bp->b_data)[bn]);
                            ++bn, ++*runp);
                        bn = ap->in_off;
                        if (runb && bn) {
                                for (--bn; bn >= 0 && *runb < maxrun &&
                                        is_sequential(ump,
                                        ((e2fs_daddr_t *)bp->b_data)[bn],
                                        ((e2fs_daddr_t *)bp->b_data)[bn + 1]);
                                        --bn, ++*runb);
                        }
                }
        }
        if (bp)
                bqrelse(bp);

        *bnp = blkptrtodb(ump, daddr);
        if (*bnp == 0) {
                *bnp = -1;
        }
        return (0);
}

static e2fs_lbn_t
lbn_count(struct ext2mount *ump, int level)

{
        e2fs_lbn_t blockcnt;

        for (blockcnt = 1; level > 0; level--)
                blockcnt *= MNINDIR(ump);
        return (blockcnt);
}

int
ext2_bmap_seekdata(struct vnode *vp, off_t *offp)
{
        struct buf *bp;
        struct indir a[EXT2_NIADDR + 1], *ap;
        struct inode *ip;
        struct mount *mp;
        struct ext2mount *ump;
        e2fs_daddr_t bn, daddr, nextbn;
        uint64_t bsize;
        off_t numblks;
        int error, num, num1, off;

        bp = NULL;
        error = 0;
        ip = VTOI(vp);
        mp = vp->v_mount;
        ump = VFSTOEXT2(mp);

        if (vp->v_type != VREG)
                return (EINVAL);
        if (*offp < 0 || *offp >= ip->i_size)
                return (ENXIO);

        bsize = mp->mnt_stat.f_iosize;
        for (bn = *offp / bsize, numblks = howmany(ip->i_size, bsize);
            bn < numblks; bn = nextbn) {
                if (bn < EXT2_NDADDR) {
                        daddr = ip->i_db[bn];
                        if (daddr != 0)
                                break;
                        nextbn = bn + 1;
                        continue;
                }

                ap = a;
                error = ext2_getlbns(vp, bn, ap, &num);
                if (error != 0)
                        break;
                MPASS(num >= 2);
                daddr = ip->i_ib[ap->in_off];
                ap++, num--;
                for (nextbn = EXT2_NDADDR, num1 = num - 1; num1 > 0; num1--)
                        nextbn += lbn_count(ump, num1);
                if (daddr == 0) {
                        nextbn += lbn_count(ump, num);
                        continue;
                }

                for (; daddr != 0 && num > 0; ap++, num--) {
                        if (bp != NULL)
                                bqrelse(bp);
                        error = readindir(vp, ap->in_lbn, daddr, &bp);
                        if (error != 0)
                                return (error);

                        /*
                         * Scan the indirect block until we find a non-zero
                         * pointer.
                         */
                        off = ap->in_off;
                        do {
                                daddr = le32toh(((e2fs_daddr_t *)bp->b_data)[off]);
                        } while (daddr == 0 && ++off < MNINDIR(ump));
                        nextbn += off * lbn_count(ump, num - 1);

                        /*
                         * We need to recompute the LBNs of indirect
                         * blocks, so restart with the updated block offset.
                         */
                        if (off != ap->in_off)
                                break;
                }
                if (num == 0) {
                        /*
                         * We found a data block.
                         */
                        bn = nextbn;
                        break;
                }
        }
        if (bp != NULL)
                bqrelse(bp);
        if (bn >= numblks)
                error = ENXIO;
        if (error == 0 && *offp < bn * bsize)
                *offp = bn * bsize;
        return (error);
}

/*
 * Create an array of logical block number/offset pairs which represent the
 * path of indirect blocks required to access a data block.  The first "pair"
 * contains the logical block number of the appropriate single, double or
 * triple indirect block and the offset into the inode indirect block array.
 * Note, the logical block number of the inode single/double/triple indirect
 * block appears twice in the array, once with the offset into the i_ib and
 * once with the offset into the page itself.
 */
int
ext2_getlbns(struct vnode *vp, daddr_t bn, struct indir *ap, int *nump)
{
        long blockcnt;
        e2fs_lbn_t metalbn, realbn;
        struct ext2mount *ump;
        int i, numlevels, off;
        int64_t qblockcnt;

        ump = VFSTOEXT2(vp->v_mount);
        if (nump)
                *nump = 0;
        numlevels = 0;
        realbn = bn;
        if ((long)bn < 0)
                bn = -(long)bn;

        /* The first EXT2_NDADDR blocks are direct blocks. */
        if (bn < EXT2_NDADDR)
                return (0);

        /*
         * Determine the number of levels of indirection.  After this loop
         * is done, blockcnt indicates the number of data blocks possible
         * at the previous level of indirection, and EXT2_NIADDR - i is the
         * number of levels of indirection needed to locate the requested block.
         */
        for (blockcnt = 1, i = EXT2_NIADDR, bn -= EXT2_NDADDR; ;
            i--, bn -= blockcnt) {
                if (i == 0)
                        return (EFBIG);
                /*
                 * Use int64_t's here to avoid overflow for triple indirect
                 * blocks when longs have 32 bits and the block size is more
                 * than 4K.
                 */
                qblockcnt = (int64_t)blockcnt * MNINDIR(ump);
                if (bn < qblockcnt)
                        break;
                blockcnt = qblockcnt;
        }

        /* Calculate the address of the first meta-block. */
        if (realbn >= 0)
                metalbn = -(realbn - bn + EXT2_NIADDR - i);
        else
                metalbn = -(-realbn - bn + EXT2_NIADDR - i);

        /*
         * At each iteration, off is the offset into the bap array which is
         * an array of disk addresses at the current level of indirection.
         * The logical block number and the offset in that block are stored
         * into the argument array.
         */
        ap->in_lbn = metalbn;
        ap->in_off = off = EXT2_NIADDR - i;
        ap++;
        for (++numlevels; i <= EXT2_NIADDR; i++) {
                /* If searching for a meta-data block, quit when found. */
                if (metalbn == realbn)
                        break;

                off = (bn / blockcnt) % MNINDIR(ump);

                ++numlevels;
                ap->in_lbn = metalbn;
                ap->in_off = off;
                ++ap;

                metalbn -= -1 + off * blockcnt;
                blockcnt /= MNINDIR(ump);
        }
        if (nump)
                *nump = numlevels;
        return (0);
}