/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include <scsi/libses.h>
#include "ses_impl.h"

ses_snap_page_t *
ses_snap_find_page(ses_snap_t *sp, ses2_diag_page_t page, boolean_t ctl)
{
        ses_snap_page_t *pp;

        for (pp = sp->ss_pages; pp != NULL; pp = pp->ssp_next)
                if (pp->ssp_num == page && pp->ssp_control == ctl &&
                    (pp->ssp_len > 0 || pp->ssp_control))
                        return (pp);

        return (NULL);
}

static int
grow_snap_page(ses_snap_page_t *pp, size_t min)
{
        uint8_t *newbuf;

        if (min == 0 || min < pp->ssp_alloc)
                min = pp->ssp_alloc * 2;

        if ((newbuf = ses_realloc(pp->ssp_page, min)) == NULL)
                return (-1);

        pp->ssp_page = newbuf;
        pp->ssp_alloc = min;

        bzero(newbuf + pp->ssp_len, pp->ssp_alloc - pp->ssp_len);

        return (0);
}

static ses_snap_page_t *
alloc_snap_page(void)
{
        ses_snap_page_t *pp;

        if ((pp = ses_zalloc(sizeof (ses_snap_page_t))) == NULL)
                return (NULL);

        if ((pp->ssp_page = ses_zalloc(SES2_MIN_DIAGPAGE_ALLOC)) == NULL) {
                ses_free(pp);
                return (NULL);
        }

        pp->ssp_num = -1;
        pp->ssp_alloc = SES2_MIN_DIAGPAGE_ALLOC;

        return (pp);
}

static void
free_snap_page(ses_snap_page_t *pp)
{
        if (pp == NULL)
                return;

        if (pp->ssp_mmap_base)
                (void) munmap(pp->ssp_mmap_base, pp->ssp_mmap_len);
        else
                ses_free(pp->ssp_page);
        ses_free(pp);
}

static void
free_all_snap_pages(ses_snap_t *sp)
{
        ses_snap_page_t *pp, *np;

        for (pp = sp->ss_pages; pp != NULL; pp = np) {
                np = pp->ssp_next;
                free_snap_page(pp);
        }

        sp->ss_pages = NULL;
}

/*
 * Grow (if needed) the control page buffer, fill in the page code, page
 * length, and generation count, and return a pointer to the page.  The
 * caller is responsible for filling in the rest of the page data.  If 'unique'
 * is specified, then a new page instance is created instead of sharing the
 * current one.
 */
ses_snap_page_t *
ses_snap_ctl_page(ses_snap_t *sp, ses2_diag_page_t page, size_t dlen,
    boolean_t unique)
{
        ses_target_t *tp = sp->ss_target;
        spc3_diag_page_impl_t *pip;
        ses_snap_page_t *pp, *up, **loc;
        ses_pagedesc_t *dp;
        size_t len;

        pp = ses_snap_find_page(sp, page, B_TRUE);
        if (pp == NULL) {
                (void) ses_set_errno(ESES_NOTSUP);
                return (NULL);
        }

        if (pp->ssp_initialized && !unique)
                return (pp);

        if (unique) {
                /*
                 * The user has requested a unique instance of the page.  Create
                 * a new ses_snap_page_t instance and chain it off the
                 * 'ssp_instances' list of the master page.  These must be
                 * appended to the end of the chain, as the order of operations
                 * may be important (i.e. microcode download).
                 */
                if ((up = alloc_snap_page()) == NULL)
                        return (NULL);

                up->ssp_num = pp->ssp_num;
                up->ssp_control = B_TRUE;

                for (loc = &pp->ssp_unique; *loc != NULL;
                    loc = &(*loc)->ssp_next)
                        ;

                *loc = up;
                pp = up;
        }

        dp = ses_get_pagedesc(tp, page, SES_PAGE_CTL);
        ASSERT(dp != NULL);

        len = dp->spd_ctl_len(sp->ss_n_elem, page, dlen);
        if (pp->ssp_alloc < len && grow_snap_page(pp, len) != 0)
                return (NULL);
        pp->ssp_len = len;
        bzero(pp->ssp_page, len);
        pp->ssp_initialized = B_TRUE;

        pip = (spc3_diag_page_impl_t *)pp->ssp_page;
        pip->sdpi_page_code = (uint8_t)page;
        SCSI_WRITE16(&pip->sdpi_page_length,
            len - offsetof(spc3_diag_page_impl_t, sdpi_data[0]));
        if (dp->spd_gcoff != -1)
                SCSI_WRITE32((uint8_t *)pip + dp->spd_gcoff, sp->ss_generation);

        return (pp);
}

static int
read_status_page(ses_snap_t *sp, ses2_diag_page_t page)
{
        libscsi_action_t *ap;
        ses_snap_page_t *pp;
        ses_target_t *tp;
        spc3_diag_page_impl_t *pip;
        spc3_receive_diagnostic_results_cdb_t *cp;
        uint_t flags;
        uint8_t *buf;
        size_t alloc;
        uint_t retries = 0;
        ses2_diag_page_t retpage;

        for (pp = sp->ss_pages; pp != NULL; pp = pp->ssp_next)
                if (pp->ssp_num == page && !pp->ssp_control)
                        break;

        /*
         * No matching page.  Since the page number is not under consumer or
         * device control, this must be a bug.
         */
        ASSERT(pp != NULL);

        tp = sp->ss_target;

        flags = LIBSCSI_AF_READ | LIBSCSI_AF_SILENT | LIBSCSI_AF_DIAGNOSE |
            LIBSCSI_AF_RQSENSE;

again:
        ap = libscsi_action_alloc(tp->st_scsi_hdl,
            SPC3_CMD_RECEIVE_DIAGNOSTIC_RESULTS, flags, pp->ssp_page,
            pp->ssp_alloc);

        if (ap == NULL)
                return (ses_libscsi_error(tp->st_scsi_hdl, "failed to "
                    "allocate SCSI action"));

        cp = (spc3_receive_diagnostic_results_cdb_t *)
            libscsi_action_get_cdb(ap);

        cp->rdrc_page_code = pp->ssp_num;
        cp->rdrc_pcv = 1;
        SCSI_WRITE16(&cp->rdrc_allocation_length,
            MIN(pp->ssp_alloc, UINT16_MAX));

        if (libscsi_exec(ap, tp->st_target) != 0) {
                libscsi_action_free(ap);
                return (ses_libscsi_error(tp->st_scsi_hdl,
                    "receive diagnostic results failed"));
        }

        if (libscsi_action_get_status(ap) != 0) {
                (void) ses_scsi_error(ap,
                    "receive diagnostic results failed");
                libscsi_action_free(ap);
                return (-1);
        }

        (void) libscsi_action_get_buffer(ap, &buf, &alloc, &pp->ssp_len);
        libscsi_action_free(ap);

        ASSERT(buf == pp->ssp_page);
        ASSERT(alloc == pp->ssp_alloc);

        if (pp->ssp_alloc - pp->ssp_len < 0x80 && pp->ssp_alloc < UINT16_MAX) {
                bzero(pp->ssp_page, pp->ssp_len);
                pp->ssp_len = 0;
                if (grow_snap_page(pp, 0) != 0)
                        return (-1);
                goto again;
        }

        if (pp->ssp_len < offsetof(spc3_diag_page_impl_t, sdpi_data)) {
                bzero(pp->ssp_page, pp->ssp_len);
                pp->ssp_len = 0;
                return (ses_error(ESES_BAD_RESPONSE, "target returned "
                    "truncated page 0x%x (length %d)", page, pp->ssp_len));
        }

        pip = (spc3_diag_page_impl_t *)buf;

        if (pip->sdpi_page_code == page)
                return (0);

        retpage = pip->sdpi_page_code;

        bzero(pp->ssp_page, pp->ssp_len);
        pp->ssp_len = 0;

        if (retpage == SES2_DIAGPAGE_ENCLOSURE_BUSY) {
                if (++retries > LIBSES_MAX_BUSY_RETRIES)
                        return (ses_error(ESES_BUSY, "too many "
                            "enclosure busy responses for page 0x%x", page));
                goto again;
        }

        return (ses_error(ESES_BAD_RESPONSE, "target returned page 0x%x "
            "instead of the requested page 0x%x", retpage, page));
}

static int
send_control_page(ses_snap_t *sp, ses_snap_page_t *pp)
{
        ses_target_t *tp;
        libscsi_action_t *ap;
        spc3_send_diagnostic_cdb_t *cp;
        uint_t flags;

        tp = sp->ss_target;

        flags = LIBSCSI_AF_WRITE | LIBSCSI_AF_SILENT | LIBSCSI_AF_DIAGNOSE |
            LIBSCSI_AF_RQSENSE;

        ap = libscsi_action_alloc(tp->st_scsi_hdl, SPC3_CMD_SEND_DIAGNOSTIC,
            flags, pp->ssp_page, pp->ssp_len);

        if (ap == NULL)
                return (ses_libscsi_error(tp->st_scsi_hdl, "failed to "
                    "allocate SCSI action"));

        cp = (spc3_send_diagnostic_cdb_t *)libscsi_action_get_cdb(ap);

        cp->sdc_pf = 1;
        SCSI_WRITE16(&cp->sdc_parameter_list_length, pp->ssp_len);

        if (libscsi_exec(ap, tp->st_target) != 0) {
                libscsi_action_free(ap);
                return (ses_libscsi_error(tp->st_scsi_hdl,
                    "SEND DIAGNOSTIC command failed for page 0x%x",
                    pp->ssp_num));
        }

        if (libscsi_action_get_status(ap) != 0) {
                (void) ses_scsi_error(ap, "SEND DIAGNOSTIC command "
                    "failed for page 0x%x", pp->ssp_num);
                libscsi_action_free(ap);
                return (-1);
        }

        libscsi_action_free(ap);

        return (0);
}

static int
pages_skel_create(ses_snap_t *sp)
{
        ses_snap_page_t *pp, *np;
        ses_target_t *tp = sp->ss_target;
        ses2_supported_ses_diag_page_impl_t *pip;
        ses2_diag_page_t page;
        size_t npages;
        size_t pagelen;
        off_t i;

        ASSERT(sp->ss_pages == NULL);

        if ((pp = alloc_snap_page()) == NULL)
                return (-1);

        pp->ssp_num = SES2_DIAGPAGE_SUPPORTED_PAGES;
        pp->ssp_control = B_FALSE;
        sp->ss_pages = pp;

        if (read_status_page(sp, SES2_DIAGPAGE_SUPPORTED_PAGES) != 0) {
                free_snap_page(pp);
                sp->ss_pages = NULL;
                return (-1);
        }

        pip = pp->ssp_page;
        pagelen = pp->ssp_len;

        npages = SCSI_READ16(&pip->sssdpi_page_length);

        for (i = 0; i < npages; i++) {
                if (!SES_WITHIN_PAGE(pip->sssdpi_pages + i, 1, pip,
                    pagelen))
                        break;

                page = (ses2_diag_page_t)pip->sssdpi_pages[i];
                /*
                 * Skip the page we already added during the bootstrap.
                 */
                if (page == SES2_DIAGPAGE_SUPPORTED_PAGES)
                        continue;
                /*
                 * The end of the page list may be padded with zeros; ignore
                 * them all.
                 */
                if (page == 0 && i > 0)
                        break;
                if ((np = alloc_snap_page()) == NULL) {
                        free_all_snap_pages(sp);
                        return (-1);
                }
                np->ssp_num = page;
                pp->ssp_next = np;
                pp = np;

                /*
                 * Allocate a control page as well, if we can use it.
                 */
                if (ses_get_pagedesc(tp, page, SES_PAGE_CTL) != NULL) {
                        if ((np = alloc_snap_page()) == NULL) {
                                free_all_snap_pages(sp);
                                return (-1);
                        }
                        np->ssp_num = page;
                        np->ssp_control = B_TRUE;
                        pp->ssp_next = np;
                        pp = np;
                }
        }

        return (0);
}

static void
ses_snap_free(ses_snap_t *sp)
{
        free_all_snap_pages(sp);
        ses_node_teardown(sp->ss_root);
        ses_free(sp->ss_nodes);
        ses_free(sp);
}

static void
ses_snap_rele_unlocked(ses_snap_t *sp)
{
        ses_target_t *tp = sp->ss_target;

        if (--sp->ss_refcnt != 0)
                return;

        if (sp->ss_next != NULL)
                sp->ss_next->ss_prev = sp->ss_prev;

        if (sp->ss_prev != NULL)
                sp->ss_prev->ss_next = sp->ss_next;
        else
                tp->st_snapshots = sp->ss_next;

        ses_snap_free(sp);
}

ses_snap_t *
ses_snap_hold(ses_target_t *tp)
{
        ses_snap_t *sp;

        (void) pthread_mutex_lock(&tp->st_lock);
        sp = tp->st_snapshots;
        sp->ss_refcnt++;
        (void) pthread_mutex_unlock(&tp->st_lock);

        return (sp);
}

void
ses_snap_rele(ses_snap_t *sp)
{
        ses_target_t *tp = sp->ss_target;

        (void) pthread_mutex_lock(&tp->st_lock);
        ses_snap_rele_unlocked(sp);
        (void) pthread_mutex_unlock(&tp->st_lock);
}

ses_snap_t *
ses_snap_new(ses_target_t *tp)
{
        ses_snap_t *sp;
        ses_snap_page_t *pp;
        uint32_t gc;
        uint_t retries = 0;
        ses_pagedesc_t *dp;
        size_t pages, pagesize, pagelen;
        char *scratch;
        boolean_t simple;

        if ((sp = ses_zalloc(sizeof (ses_snap_t))) == NULL)
                return (NULL);

        sp->ss_target = tp;

again:
        free_all_snap_pages(sp);

        if (pages_skel_create(sp) != 0) {
                free(sp);
                return (NULL);
        }

        sp->ss_generation = (uint32_t)-1;
        sp->ss_time = gethrtime();

        /*
         * First check for the short enclosure status diagnostic page and
         * determine if this is a simple subenclosure or not.
         */
        simple = B_FALSE;
        for (pp = sp->ss_pages; pp != NULL; pp = pp->ssp_next) {
                if (pp->ssp_num == SES2_DIAGPAGE_SHORT_STATUS)
                        simple = B_TRUE;
        }

        for (pp = sp->ss_pages; pp != NULL; pp = pp->ssp_next) {
                /*
                 * We skip all of:
                 *
                 * - Control pages
                 * - Pages we've already filled in
                 * - Pages we don't understand (those with no descriptor)
                 */
                if (pp->ssp_len > 0 || pp->ssp_control)
                        continue;
                if ((dp = ses_get_pagedesc(tp, pp->ssp_num,
                    SES_PAGE_DIAG)) == NULL)
                        continue;

                if (read_status_page(sp, pp->ssp_num) != 0)  {
                        /*
                         * If this page is required, and this is not a simple
                         * subenclosure, then fail the entire snapshot.
                         */
                        if (dp->spd_req == SES_REQ_MANDATORY_ALL ||
                            (dp->spd_req == SES_REQ_MANDATORY_STANDARD &&
                            !simple)) {
                                ses_snap_free(sp);
                                return (NULL);
                        }

                        continue;
                }

                /*
                 * If the generation code has changed, we don't have a valid
                 * snapshot.  Start over.
                 */
                if (dp->spd_gcoff != -1 &&
                    dp->spd_gcoff + 4 <= pp->ssp_len) {
                        gc = SCSI_READ32((uint8_t *)pp->ssp_page +
                            dp->spd_gcoff);
                        if (sp->ss_generation == (uint32_t)-1) {
                                sp->ss_generation = gc;
                        } else if (sp->ss_generation != gc) {
                                if (++retries > LIBSES_MAX_GC_RETRIES) {
                                        (void) ses_error(ESES_TOOMUCHCHANGE,
                                            "too many generation count "
                                            "mismatches: page 0x%x gc %u "
                                            "previous page %u", dp->spd_gcoff,
                                            gc, sp->ss_generation);
                                        ses_snap_free((ses_snap_t *)sp);
                                        return (NULL);
                                }
                                goto again;
                        }
                }
        }

        /*
         * The LIBSES_TRUNCATE environment variable is a debugging tool which,
         * if set, randomly truncates all pages (except
         * SES2_DIAGPAGE_SUPPORTED_PAGES).  In order to be truly evil, we
         * mmap() each page with enough space after it so we can move the data
         * up to the end of a page and unmap the following page so that any
         * attempt to read past the end of the page results in a segfault.
         */
        if (sp->ss_target->st_truncate) {
                pagesize = PAGESIZE;

                /*
                 * Count the maximum number of pages we will need and allocate
                 * the necessary space.
                 */
                pages = 0;
                for (pp = sp->ss_pages; pp != NULL; pp = pp->ssp_next) {
                        if (pp->ssp_control || pp->ssp_len == 0)
                                continue;

                        pages += (P2ROUNDUP(pp->ssp_len, pagesize) /
                            pagesize) + 1;
                }

                if ((scratch = mmap(NULL, pages * pagesize,
                    PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE,
                    -1, 0)) == MAP_FAILED) {
                        (void) ses_error(ESES_NOMEM,
                            "failed to mmap() pages for truncation");
                        ses_snap_free(sp);
                        return (NULL);
                }

                for (pp = sp->ss_pages; pp != NULL; pp = pp->ssp_next) {
                        if (pp->ssp_control || pp->ssp_len == 0)
                                continue;

                        pages = P2ROUNDUP(pp->ssp_len, pagesize) / pagesize;
                        pp->ssp_mmap_base = scratch;
                        pp->ssp_mmap_len = pages * pagesize;

                        pagelen = lrand48() % pp->ssp_len;
                        (void) memcpy(pp->ssp_mmap_base + pp->ssp_mmap_len -
                            pagelen, pp->ssp_page, pagelen);
                        ses_free(pp->ssp_page);
                        pp->ssp_page = pp->ssp_mmap_base + pp->ssp_mmap_len -
                            pagelen;
                        pp->ssp_len = pagelen;

                        (void) munmap(pp->ssp_mmap_base + pages * pagesize,
                            pagesize);
                        scratch += (pages + 1) * pagesize;
                }
        }


        if (ses_fill_snap(sp) != 0) {
                ses_snap_free(sp);
                return (NULL);
        }

        (void) pthread_mutex_lock(&tp->st_lock);
        if (tp->st_snapshots != NULL)
                ses_snap_rele_unlocked(tp->st_snapshots);
        sp->ss_next = tp->st_snapshots;
        if (tp->st_snapshots != NULL)
                tp->st_snapshots->ss_prev = sp;
        tp->st_snapshots = sp;
        sp->ss_refcnt = 2;
        (void) pthread_mutex_unlock(&tp->st_lock);

        return (sp);
}

int
ses_snap_do_ctl(ses_snap_t *sp)
{
        ses_snap_page_t *pp, *up;
        int ret = -1;

        for (pp = sp->ss_pages; pp != NULL; pp = pp->ssp_next) {
                if (!pp->ssp_control)
                        continue;

                if (pp->ssp_initialized && send_control_page(sp, pp) != 0)
                        goto error;

                for (up = pp->ssp_unique; up != NULL; up = up->ssp_next) {
                        if (send_control_page(sp, up) != 0)
                                goto error;
                }
        }

        ret = 0;
error:
        for (pp = sp->ss_pages; pp != NULL; pp = pp->ssp_next) {
                if (!pp->ssp_control)
                        continue;

                pp->ssp_initialized = B_FALSE;
                while ((up = pp->ssp_unique) != NULL) {
                        pp->ssp_unique = up->ssp_next;
                        free_snap_page(up);
                }
        }


        return (ret);
}

uint32_t
ses_snap_generation(ses_snap_t *sp)
{
        return (sp->ss_generation);
}

static ses_walk_action_t
ses_walk_node(ses_node_t *np, ses_walk_f func, void *arg)
{
        ses_walk_action_t action;

        for (; np != NULL; np = ses_node_sibling(np)) {
                action = func(np, arg);
                if (action == SES_WALK_ACTION_TERMINATE)
                        return (SES_WALK_ACTION_TERMINATE);
                if (action == SES_WALK_ACTION_PRUNE ||
                    ses_node_child(np) == NULL)
                        continue;
                if (ses_walk_node(ses_node_child(np), func, arg) ==
                    SES_WALK_ACTION_TERMINATE)
                        return (SES_WALK_ACTION_TERMINATE);
        }

        return (SES_WALK_ACTION_CONTINUE);
}

int
ses_walk(ses_snap_t *sp, ses_walk_f func, void *arg)
{
        (void) ses_walk_node(ses_root_node(sp), func, arg);

        return (0);
}

/*ARGSUSED*/
static ses_walk_action_t
ses_fill_nodes(ses_node_t *np, void *unused)
{
        np->sn_snapshot->ss_nodes[np->sn_id] = np;

        return (SES_WALK_ACTION_CONTINUE);
}

/*
 * Given an ID returned by ses_node_id(), lookup and return the corresponding
 * node in the snapshot.  If the snapshot generation count has changed, then
 * return failure.
 */
ses_node_t *
ses_node_lookup(ses_snap_t *sp, uint64_t id)
{
        uint32_t gen = (id >> 32);
        uint32_t idx = (id & 0xFFFFFFFF);

        if (sp->ss_generation != gen) {
                (void) ses_set_errno(ESES_CHANGED);
                return (NULL);
        }

        if (idx >= sp->ss_n_nodes) {
                (void) ses_error(ESES_BAD_NODE,
                    "no such node in snapshot");
                return (NULL);
        }

        /*
         * If this is our first lookup attempt, construct the array for fast
         * lookups.
         */
        if (sp->ss_nodes == NULL) {
                if ((sp->ss_nodes = ses_zalloc(
                    sp->ss_n_nodes * sizeof (void *))) == NULL)
                        return (NULL);

                (void) ses_walk(sp, ses_fill_nodes, NULL);
        }

        if (sp->ss_nodes[idx] == NULL)
                (void) ses_error(ESES_BAD_NODE,
                    "no such node in snapshot");
        return (sp->ss_nodes[idx]);
}