#include <linux/ceph/ceph_debug.h>

#include <linux/bug.h>
#include <linux/err.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/types.h>

#include <linux/ceph/mdsmap.h>
#include <linux/ceph/messenger.h>
#include <linux/ceph/decode.h>

#include "super.h"


/*
 * choose a random mds that is "up" (i.e. has a state > 0), or -1.
 */
int ceph_mdsmap_get_random_mds(struct ceph_mdsmap *m)
{
        int n = 0;
        int i;
        char r;

        /* count */
        for (i = 0; i < m->m_max_mds; i++)
                if (m->m_info[i].state > 0)
                        n++;
        if (n == 0)
                return -1;

        /* pick */
        get_random_bytes(&r, 1);
        n = r % n;
        i = 0;
        for (i = 0; n > 0; i++, n--)
                while (m->m_info[i].state <= 0)
                        i++;

        return i;
}

/*
 * Decode an MDS map
 *
 * Ignore any fields we don't care about (there are quite a few of
 * them).
 */
struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end)
{
        struct ceph_mdsmap *m;
        const void *start = *p;
        int i, j, n;
        int err = -EINVAL;
        u16 version;

        m = kzalloc(sizeof(*m), GFP_NOFS);
        if (m == NULL)
                return ERR_PTR(-ENOMEM);

        ceph_decode_16_safe(p, end, version, bad);

        ceph_decode_need(p, end, 8*sizeof(u32) + sizeof(u64), bad);
        m->m_epoch = ceph_decode_32(p);
        m->m_client_epoch = ceph_decode_32(p);
        m->m_last_failure = ceph_decode_32(p);
        m->m_root = ceph_decode_32(p);
        m->m_session_timeout = ceph_decode_32(p);
        m->m_session_autoclose = ceph_decode_32(p);
        m->m_max_file_size = ceph_decode_64(p);
        m->m_max_mds = ceph_decode_32(p);

        m->m_info = kcalloc(m->m_max_mds, sizeof(*m->m_info), GFP_NOFS);
        if (m->m_info == NULL)
                goto badmem;

        /* pick out active nodes from mds_info (state > 0) */
        n = ceph_decode_32(p);
        for (i = 0; i < n; i++) {
                u64 global_id;
                u32 namelen;
                s32 mds, inc, state;
                u64 state_seq;
                u8 infoversion;
                struct ceph_entity_addr addr;
                u32 num_export_targets;
                void *pexport_targets = NULL;
                struct ceph_timespec laggy_since;

                ceph_decode_need(p, end, sizeof(u64)*2 + 1 + sizeof(u32), bad);
                global_id = ceph_decode_64(p);
                infoversion = ceph_decode_8(p);
                *p += sizeof(u64);
                namelen = ceph_decode_32(p);  /* skip mds name */
                *p += namelen;

                ceph_decode_need(p, end,
                                 4*sizeof(u32) + sizeof(u64) +
                                 sizeof(addr) + sizeof(struct ceph_timespec),
                                 bad);
                mds = ceph_decode_32(p);
                inc = ceph_decode_32(p);
                state = ceph_decode_32(p);
                state_seq = ceph_decode_64(p);
                ceph_decode_copy(p, &addr, sizeof(addr));
                ceph_decode_addr(&addr);
                ceph_decode_copy(p, &laggy_since, sizeof(laggy_since));
                *p += sizeof(u32);
                ceph_decode_32_safe(p, end, namelen, bad);
                *p += namelen;
                if (infoversion >= 2) {
                        ceph_decode_32_safe(p, end, num_export_targets, bad);
                        pexport_targets = *p;
                        *p += num_export_targets * sizeof(u32);
                } else {
                        num_export_targets = 0;
                }

                dout("mdsmap_decode %d/%d %lld mds%d.%d %s %s\n",
                     i+1, n, global_id, mds, inc,
                     ceph_pr_addr(&addr.in_addr),
                     ceph_mds_state_name(state));
                if (mds >= 0 && mds < m->m_max_mds && state > 0) {
                        m->m_info[mds].global_id = global_id;
                        m->m_info[mds].state = state;
                        m->m_info[mds].addr = addr;
                        m->m_info[mds].laggy =
                                (laggy_since.tv_sec != 0 ||
                                 laggy_since.tv_nsec != 0);
                        m->m_info[mds].num_export_targets = num_export_targets;
                        if (num_export_targets) {
                                m->m_info[mds].export_targets =
                                        kcalloc(num_export_targets, sizeof(u32),
                                                GFP_NOFS);
                                for (j = 0; j < num_export_targets; j++)
                                        m->m_info[mds].export_targets[j] =
                                               ceph_decode_32(&pexport_targets);
                        } else {
                                m->m_info[mds].export_targets = NULL;
                        }
                }
        }

        /* pg_pools */
        ceph_decode_32_safe(p, end, n, bad);
        m->m_num_data_pg_pools = n;
        m->m_data_pg_pools = kcalloc(n, sizeof(u32), GFP_NOFS);
        if (!m->m_data_pg_pools)
                goto badmem;
        ceph_decode_need(p, end, sizeof(u32)*(n+1), bad);
        for (i = 0; i < n; i++)
                m->m_data_pg_pools[i] = ceph_decode_32(p);
        m->m_cas_pg_pool = ceph_decode_32(p);

        /* ok, we don't care about the rest. */
        dout("mdsmap_decode success epoch %u\n", m->m_epoch);
        return m;

badmem:
        err = -ENOMEM;
bad:
        pr_err("corrupt mdsmap\n");
        print_hex_dump(KERN_DEBUG, "mdsmap: ",
                       DUMP_PREFIX_OFFSET, 16, 1,
                       start, end - start, true);
        ceph_mdsmap_destroy(m);
        return ERR_PTR(-EINVAL);
}

void ceph_mdsmap_destroy(struct ceph_mdsmap *m)
{
        int i;

        for (i = 0; i < m->m_max_mds; i++)
                kfree(m->m_info[i].export_targets);
        kfree(m->m_info);
        kfree(m->m_data_pg_pools);
        kfree(m);
}