/*      $NetBSD: rumpblk.c,v 1.64 2016/07/07 06:55:44 msaitoh Exp $     */

/*
 * Copyright (c) 2009 Antti Kantee.  All Rights Reserved.
 *
 * Development of this software was supported by the
 * Finnish Cultural Foundation.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

/*
 * Block device emulation.  Presents a block device interface and
 * uses rumpuser system calls to satisfy I/O requests.
 *
 * We provide fault injection.  The driver can be made to fail
 * I/O occasionally.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: rumpblk.c,v 1.64 2016/07/07 06:55:44 msaitoh Exp $");

#include <sys/param.h>
#include <sys/buf.h>
#include <sys/conf.h>
#include <sys/condvar.h>
#include <sys/disklabel.h>
#include <sys/evcnt.h>
#include <sys/fcntl.h>
#include <sys/kmem.h>
#include <sys/malloc.h>
#include <sys/queue.h>
#include <sys/stat.h>
#include <sys/cprng.h>

#include <rump-sys/kern.h>
#include <rump-sys/vfs.h>

#include <rump/rumpuser.h>

#if 0
#define DPRINTF(x) printf x
#else
#define DPRINTF(x)
#endif

#define RUMPBLK_SIZE 16
static struct rblkdev {
        char *rblk_path;
        int rblk_fd;
        int rblk_mode;

        uint64_t rblk_size;
        uint64_t rblk_hostoffset;
        uint64_t rblk_hostsize;
        int rblk_ftype;

        struct disklabel rblk_label;
} minors[RUMPBLK_SIZE];

static struct evcnt ev_io_total;
static struct evcnt ev_io_async;

static struct evcnt ev_bwrite_total;
static struct evcnt ev_bwrite_async;
static struct evcnt ev_bread_total;

dev_type_open(rumpblk_open);
dev_type_close(rumpblk_close);
dev_type_read(rumpblk_read);
dev_type_write(rumpblk_write);
dev_type_ioctl(rumpblk_ioctl);
dev_type_strategy(rumpblk_strategy);
dev_type_strategy(rumpblk_strategy_fail);
dev_type_dump(rumpblk_dump);
dev_type_size(rumpblk_size);

static const struct bdevsw rumpblk_bdevsw = {
        .d_open = rumpblk_open,
        .d_close = rumpblk_close,
        .d_strategy = rumpblk_strategy,
        .d_ioctl = rumpblk_ioctl,
        .d_dump = nodump,
        .d_psize = nosize,
        .d_discard = nodiscard,
        .d_flag = D_DISK
};

static const struct bdevsw rumpblk_bdevsw_fail = {
        .d_open = rumpblk_open,
        .d_close = rumpblk_close,
        .d_strategy = rumpblk_strategy_fail,
        .d_ioctl = rumpblk_ioctl,
        .d_dump = nodump,
        .d_psize = nosize,
        .d_discard = nodiscard,
        .d_flag = D_DISK
};

static const struct cdevsw rumpblk_cdevsw = {
        .d_open = rumpblk_open,
        .d_close = rumpblk_close,
        .d_read = rumpblk_read,
        .d_write = rumpblk_write,
        .d_ioctl = rumpblk_ioctl,
        .d_stop = nostop,
        .d_tty = notty,
        .d_poll = nopoll,
        .d_mmap = nommap,
        .d_kqfilter = nokqfilter,
        .d_discard = nodiscard,
        .d_flag = D_DISK
};

static int backend_open(struct rblkdev *, const char *);
static int backend_close(struct rblkdev *);

/* fail every n out of BLKFAIL_MAX */
#define BLKFAIL_MAX 10000
static int blkfail;
static unsigned randstate;
static kmutex_t rumpblk_lock;
static int sectshift = DEV_BSHIFT;

static void
makedefaultlabel(struct disklabel *lp, off_t size, int part)
{
        int i;

        memset(lp, 0, sizeof(*lp));

        lp->d_secperunit = size;
        lp->d_secsize = 1 << sectshift;
        lp->d_nsectors = size >> sectshift;
        lp->d_ntracks = 1;
        lp->d_ncylinders = 1;
        lp->d_secpercyl = lp->d_nsectors;

        /* oh dear oh dear */
        strncpy(lp->d_typename, "rumpd", sizeof(lp->d_typename));
        strncpy(lp->d_packname, "fictitious", sizeof(lp->d_packname));

        lp->d_type = DKTYPE_RUMPD;
        lp->d_rpm = 11;
        lp->d_interleave = 1;
        lp->d_flags = 0;

        /* XXX: RAW_PART handling? */
        for (i = 0; i < part; i++) {
                lp->d_partitions[i].p_fstype = FS_UNUSED;
        }
        lp->d_partitions[part].p_size = size >> sectshift;
        lp->d_npartitions = part+1;
        /* XXX: file system type? */

        lp->d_magic = DISKMAGIC;
        lp->d_magic2 = DISKMAGIC;
        lp->d_checksum = 0; /* XXX */
}

int
rumpblk_init(void)
{
        char buf[64];
        devmajor_t rumpblkmaj = RUMPBLK_DEVMAJOR;
        unsigned tmp;
        int i;

        mutex_init(&rumpblk_lock, MUTEX_DEFAULT, IPL_NONE);

        if (rumpuser_getparam("RUMP_BLKFAIL", buf, sizeof(buf)) == 0) {
                blkfail = strtoul(buf, NULL, 10);
                /* fail everything */
                if (blkfail > BLKFAIL_MAX)
                        blkfail = BLKFAIL_MAX;
                if (rumpuser_getparam("RUMP_BLKFAIL_SEED",
                    buf, sizeof(buf)) == 0) {
                        randstate = strtoul(buf, NULL, 10);
                } else {
                        randstate = cprng_fast32();
                }
                printf("rumpblk: FAULT INJECTION ACTIVE! fail %d/%d. "
                    "seed %u\n", blkfail, BLKFAIL_MAX, randstate);
        } else {
                blkfail = 0;
        }

        if (rumpuser_getparam("RUMP_BLKSECTSHIFT", buf, sizeof(buf)) == 0) {
                printf("rumpblk: ");
                tmp = strtoul(buf, NULL, 10);
                if (tmp >= DEV_BSHIFT)
                        sectshift = tmp;
                else
                        printf("RUMP_BLKSECTSHIFT must be least %d (now %d), ",
                           DEV_BSHIFT, tmp);
                printf("using %d for sector shift (size %d)\n",
                    sectshift, 1<<sectshift);
        }

        memset(minors, 0, sizeof(minors));
        for (i = 0; i < RUMPBLK_SIZE; i++) {
                minors[i].rblk_fd = -1;
        }

        evcnt_attach_dynamic(&ev_io_total, EVCNT_TYPE_MISC, NULL,
            "rumpblk", "I/O reqs");
        evcnt_attach_dynamic(&ev_io_async, EVCNT_TYPE_MISC, NULL,
            "rumpblk", "async I/O");

        evcnt_attach_dynamic(&ev_bread_total, EVCNT_TYPE_MISC, NULL,
            "rumpblk", "bytes read");
        evcnt_attach_dynamic(&ev_bwrite_total, EVCNT_TYPE_MISC, NULL,
            "rumpblk", "bytes written");
        evcnt_attach_dynamic(&ev_bwrite_async, EVCNT_TYPE_MISC, NULL,
            "rumpblk", "bytes written async");

        if (blkfail) {
                return devsw_attach("rumpblk",
                    &rumpblk_bdevsw_fail, &rumpblkmaj,
                    &rumpblk_cdevsw, &rumpblkmaj);
        } else {
                return devsw_attach("rumpblk",
                    &rumpblk_bdevsw, &rumpblkmaj,
                    &rumpblk_cdevsw, &rumpblkmaj);
        }
}

int
rumpblk_register(const char *path, devminor_t *dmin,
        uint64_t offset, uint64_t size)
{
        struct rblkdev *rblk;
        uint64_t flen;
        size_t len;
        int ftype, error, i;

        /* devices might not report correct size unless they're open */
        if ((error = rumpuser_getfileinfo(path, &flen, &ftype)) != 0)
                return error;

        /* verify host file is of supported type */
        if (!(ftype == RUMPUSER_FT_REG
           || ftype == RUMPUSER_FT_BLK
           || ftype == RUMPUSER_FT_CHR))
                return EINVAL;

        mutex_enter(&rumpblk_lock);
        for (i = 0; i < RUMPBLK_SIZE; i++) {
                if (minors[i].rblk_path&&strcmp(minors[i].rblk_path, path)==0) {
                        mutex_exit(&rumpblk_lock);
                        *dmin = i;
                        return 0;
                }
        }

        for (i = 0; i < RUMPBLK_SIZE; i++)
                if (minors[i].rblk_path == NULL)
                        break;
        if (i == RUMPBLK_SIZE) {
                mutex_exit(&rumpblk_lock);
                return EBUSY;
        }

        rblk = &minors[i];
        rblk->rblk_path = __UNCONST("taken");
        mutex_exit(&rumpblk_lock);

        len = strlen(path);
        rblk->rblk_path = malloc(len + 1, M_TEMP, M_WAITOK);
        strcpy(rblk->rblk_path, path);
        rblk->rblk_hostoffset = offset;
        if (size != RUMPBLK_SIZENOTSET) {
                KASSERT(size + offset <= flen);
                rblk->rblk_size = size;
        } else {
                KASSERT(offset < flen);
                rblk->rblk_size = flen - offset;
        }
        rblk->rblk_hostsize = flen;
        rblk->rblk_ftype = ftype;
        makedefaultlabel(&rblk->rblk_label, rblk->rblk_size, i);

        if ((error = backend_open(rblk, path)) != 0) {
                memset(&rblk->rblk_label, 0, sizeof(rblk->rblk_label));
                free(rblk->rblk_path, M_TEMP);
                rblk->rblk_path = NULL;
                return error;
        }

        *dmin = i;
        return 0;
}

/*
 * Unregister rumpblk.  It's the callers responsibility to make
 * sure it's no longer in use.
 */
int
rumpblk_deregister(const char *path)
{
        struct rblkdev *rblk;
        int i;

        mutex_enter(&rumpblk_lock);
        for (i = 0; i < RUMPBLK_SIZE; i++) {
                if (minors[i].rblk_path&&strcmp(minors[i].rblk_path, path)==0) {
                        break;
                }
        }
        mutex_exit(&rumpblk_lock);

        if (i == RUMPBLK_SIZE)
                return ENOENT;

        rblk = &minors[i];
        backend_close(rblk);

        free(rblk->rblk_path, M_TEMP);
        memset(&rblk->rblk_label, 0, sizeof(rblk->rblk_label));
        rblk->rblk_path = NULL;

        return 0;
}

/*
 * Release all backend resources, to be called only when the rump
 * kernel is being shut down.
 * This routine does not do a full "fini" since we're going down anyway.
 */
void
rumpblk_fini(void)
{
        int i;

        for (i = 0; i < RUMPBLK_SIZE; i++) {
                struct rblkdev *rblk;

                rblk = &minors[i];
                if (rblk->rblk_fd != -1)
                        backend_close(rblk);
        }
}

static int
backend_open(struct rblkdev *rblk, const char *path)
{
        int error, fd;

        KASSERT(rblk->rblk_fd == -1);
        error = rumpuser_open(path,
            RUMPUSER_OPEN_RDWR | RUMPUSER_OPEN_BIO, &fd);
        if (error) {
                error = rumpuser_open(path,
                    RUMPUSER_OPEN_RDONLY | RUMPUSER_OPEN_BIO, &fd);
                if (error)
                        return error;
                rblk->rblk_mode = FREAD;
        } else {
                rblk->rblk_mode = FREAD|FWRITE;
        }

        rblk->rblk_fd = fd;
        KASSERT(rblk->rblk_fd != -1);
        return 0;
}

static int
backend_close(struct rblkdev *rblk)
{

        rumpuser_close(rblk->rblk_fd);
        rblk->rblk_fd = -1;

        return 0;
}

int
rumpblk_open(dev_t dev, int flag, int fmt, struct lwp *l)
{
        struct rblkdev *rblk = &minors[minor(dev)];

        if (rblk->rblk_fd == -1)
                return ENXIO;

        if (((flag & (FREAD|FWRITE)) & ~rblk->rblk_mode) != 0) {
                return EACCES;
        }

        return 0;
}

int
rumpblk_close(dev_t dev, int flag, int fmt, struct lwp *l)
{

        return 0;
}

int
rumpblk_ioctl(dev_t dev, u_long xfer, void *addr, int flag, struct lwp *l)
{
        devminor_t dmin = minor(dev);
        struct rblkdev *rblk = &minors[dmin];
        struct partinfo *pi;
        struct partition *dp;
        int error = 0;

        /* well, me should support a few more, but we don't for now */
        switch (xfer) {
        case DIOCGDINFO:
                *(struct disklabel *)addr = rblk->rblk_label;
                break;

        case DIOCGPARTINFO:
                dp = &rblk->rblk_label.d_partitions[DISKPART(dmin)];
                pi = addr;
                pi->pi_offset = dp->p_offset;
                pi->pi_size = dp->p_size;
                pi->pi_secsize = rblk->rblk_label.d_secsize;
                pi->pi_bsize = BLKDEV_IOSIZE;
                pi->pi_fstype = dp->p_fstype;
                pi->pi_fsize = dp->p_fsize;
                pi->pi_frag = dp->p_frag;
                pi->pi_cpg = dp->p_cpg;
                break;

        /* it's synced enough along the write path */
        case DIOCCACHESYNC:
                break;

        case DIOCGMEDIASIZE:
                *(off_t *)addr = (off_t)rblk->rblk_size;
                break;

        default:
                error = ENOTTY;
                break;
        }

        return error;
}

static int
do_physio(dev_t dev, struct uio *uio, int which)
{
        void (*strat)(struct buf *);

        if (blkfail)
                strat = rumpblk_strategy_fail;
        else
                strat = rumpblk_strategy;

        return physio(strat, NULL, dev, which, minphys, uio);
}

int
rumpblk_read(dev_t dev, struct uio *uio, int flags)
{

        return do_physio(dev, uio, B_READ);
}

int
rumpblk_write(dev_t dev, struct uio *uio, int flags)
{

        return do_physio(dev, uio, B_WRITE);
}

static void
dostrategy(struct buf *bp)
{
        struct rblkdev *rblk = &minors[minor(bp->b_dev)];
        off_t off;
        int async = bp->b_flags & B_ASYNC;
        int op;

        if (bp->b_bcount % (1<<sectshift) != 0) {
                rump_biodone(bp, 0, EINVAL);
                return;
        }

        /* collect statistics */
        ev_io_total.ev_count++;
        if (async)
                ev_io_async.ev_count++;
        if (BUF_ISWRITE(bp)) {
                ev_bwrite_total.ev_count += bp->b_bcount;
                if (async)
                        ev_bwrite_async.ev_count += bp->b_bcount;
        } else {
                ev_bread_total.ev_count++;
        }

        /*
         * b_blkno is always in terms of DEV_BSIZE, and since we need
         * to translate to a byte offset for the host read, this
         * calculation does not need sectshift.
         */
        off = bp->b_blkno << DEV_BSHIFT;

        /*
         * Do bounds checking if we're working on a file.  Otherwise
         * invalid file systems might attempt to read beyond EOF.  This
         * is bad(tm) especially on mmapped images.  This is essentially
         * the kernel bounds_check() routines.
         */
        if (off + bp->b_bcount > rblk->rblk_size) {
                int64_t sz = rblk->rblk_size - off;

                /* EOF */
                if (sz == 0) {
                        rump_biodone(bp, 0, 0);
                        return;
                }
                /* beyond EOF ==> error */
                if (sz < 0) {
                        rump_biodone(bp, 0, EINVAL);
                        return;
                }

                /* truncate to device size */
                bp->b_bcount = sz;
        }

        off += rblk->rblk_hostoffset;
        DPRINTF(("rumpblk_strategy: 0x%x bytes %s off 0x%" PRIx64
            " (0x%" PRIx64 " - 0x%" PRIx64 "), %ssync\n",
            bp->b_bcount, BUF_ISREAD(bp) ? "READ" : "WRITE",
            off, off, (off + bp->b_bcount), async ? "a" : ""));

        op = BUF_ISREAD(bp) ? RUMPUSER_BIO_READ : RUMPUSER_BIO_WRITE;
        if (BUF_ISWRITE(bp) && !async)
                op |= RUMPUSER_BIO_SYNC;

        rumpuser_bio(rblk->rblk_fd, op, bp->b_data, bp->b_bcount, off,
            rump_biodone, bp);
}

void
rumpblk_strategy(struct buf *bp)
{

        dostrategy(bp);
}

/*
 * Simple random number generator.  This is private so that we can
 * very repeatedly control which blocks will fail.
 *
 * <mlelstv> pooka, rand()
 * <mlelstv> [paste]
 */
static unsigned
gimmerand(void)
{

        return (randstate = randstate * 1103515245 + 12345) % (0x80000000L);
}

/*
 * Block device with very simple fault injection.  Fails every
 * n out of BLKFAIL_MAX I/O with EIO.  n is determined by the env
 * variable RUMP_BLKFAIL.
 */
void
rumpblk_strategy_fail(struct buf *bp)
{

        if (gimmerand() % BLKFAIL_MAX >= blkfail) {
                dostrategy(bp);
        } else { 
                printf("block fault injection: failing I/O on block %lld\n",
                    (long long)bp->b_blkno);
                bp->b_error = EIO;
                biodone(bp);
        }
}