// SPDX-License-Identifier: GPL-2.0
#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/messenger.h>
#include <linux/ceph/decode.h>

#include "mdsmap.h"
#include "mds_client.h"
#include "super.h"

#define CEPH_MDS_IS_READY(i, ignore_laggy) \
        (m->m_info[i].state > 0 && ignore_laggy ? true : !m->m_info[i].laggy)

static int __mdsmap_get_random_mds(struct ceph_mdsmap *m, bool ignore_laggy)
{
        int n = 0;
        int i, j;

        /* count */
        for (i = 0; i < m->possible_max_rank; i++)
                if (CEPH_MDS_IS_READY(i, ignore_laggy))
                        n++;
        if (n == 0)
                return -1;

        /* pick */
        n = get_random_u32_below(n);
        for (j = 0, i = 0; i < m->possible_max_rank; i++) {
                if (CEPH_MDS_IS_READY(i, ignore_laggy))
                        j++;
                if (j > n)
                        break;
        }

        return i;
}

/*
 * 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 mds;

        mds = __mdsmap_get_random_mds(m, false);
        if (mds == m->possible_max_rank || mds == -1)
                mds = __mdsmap_get_random_mds(m, true);

        return mds == m->possible_max_rank ? -1 : mds;
}

#define __decode_and_drop_type(p, end, type, bad)               \
        do {                                                    \
                if (*p + sizeof(type) > end)                    \
                        goto bad;                               \
                *p += sizeof(type);                             \
        } while (0)

#define __decode_and_drop_set(p, end, type, bad)                \
        do {                                                    \
                u32 n;                                          \
                size_t need;                                    \
                ceph_decode_32_safe(p, end, n, bad);            \
                need = sizeof(type) * n;                        \
                ceph_decode_need(p, end, need, bad);            \
                *p += need;                                     \
        } while (0)

#define __decode_and_drop_map(p, end, ktype, vtype, bad)        \
        do {                                                    \
                u32 n;                                          \
                size_t need;                                    \
                ceph_decode_32_safe(p, end, n, bad);            \
                need = (sizeof(ktype) + sizeof(vtype)) * n;     \
                ceph_decode_need(p, end, need, bad);            \
                *p += need;                                     \
        } while (0)


static int __decode_and_drop_compat_set(void **p, void* end)
{
        int i;
        /* compat, ro_compat, incompat*/
        for (i = 0; i < 3; i++) {
                u32 n;
                ceph_decode_need(p, end, sizeof(u64) + sizeof(u32), bad);
                /* mask */
                *p += sizeof(u64);
                /* names (map<u64, string>) */
                n = ceph_decode_32(p);
                while (n-- > 0) {
                        u32 len;
                        ceph_decode_need(p, end, sizeof(u64) + sizeof(u32),
                                         bad);
                        *p += sizeof(u64);
                        len = ceph_decode_32(p);
                        ceph_decode_need(p, end, len, bad);
                        *p += len;
                }
        }
        return 0;
bad:
        return -1;
}

/*
 * 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(struct ceph_mds_client *mdsc, void **p,
                                       void *end, bool msgr2)
{
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_mdsmap *m;
        const void *start = *p;
        int i, j, n;
        int err;
        u8 mdsmap_v;
        u16 mdsmap_ev;
        u32 target;

        m = kzalloc_obj(*m, GFP_NOFS);
        if (!m)
                return ERR_PTR(-ENOMEM);

        ceph_decode_need(p, end, 1 + 1, bad);
        mdsmap_v = ceph_decode_8(p);
        *p += sizeof(u8);                       /* mdsmap_cv */
        if (mdsmap_v >= 4) {
               u32 mdsmap_len;
               ceph_decode_32_safe(p, end, mdsmap_len, bad);
               if (end < *p + mdsmap_len)
                       goto bad;
               end = *p + mdsmap_len;
        }

        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);

        /*
         * pick out the active nodes as the m_num_active_mds, the
         * m_num_active_mds maybe larger than m_max_mds when decreasing
         * the max_mds in cluster side, in other case it should less
         * than or equal to m_max_mds.
         */
        m->m_num_active_mds = n = ceph_decode_32(p);

        /*
         * the possible max rank, it maybe larger than the m_num_active_mds,
         * for example if the mds_max == 2 in the cluster, when the MDS(0)
         * was laggy and being replaced by a new MDS, we will temporarily
         * receive a new mds map with n_num_mds == 1 and the active MDS(1),
         * and the mds rank >= m_num_active_mds.
         */
        m->possible_max_rank = max(m->m_num_active_mds, m->m_max_mds);

        m->m_info = kzalloc_objs(*m->m_info, m->possible_max_rank, GFP_NOFS);
        if (!m->m_info)
                goto nomem;

        /* pick out active nodes from mds_info (state > 0) */
        for (i = 0; i < n; i++) {
                u64 global_id;
                u32 namelen;
                s32 mds, inc, state;
                u8 info_v;
                void *info_end = NULL;
                struct ceph_entity_addr addr;
                u32 num_export_targets;
                void *pexport_targets = NULL;
                struct ceph_timespec laggy_since;
                struct ceph_mds_info *info;
                bool laggy;

                ceph_decode_need(p, end, sizeof(u64) + 1, bad);
                global_id = ceph_decode_64(p);
                info_v= ceph_decode_8(p);
                if (info_v >= 4) {
                        u32 info_len;
                        ceph_decode_need(p, end, 1 + sizeof(u32), bad);
                        *p += sizeof(u8);       /* info_cv */
                        info_len = ceph_decode_32(p);
                        info_end = *p + info_len;
                        if (info_end > end)
                                goto bad;
                }

                ceph_decode_need(p, end, sizeof(u64) + sizeof(u32), bad);
                *p += sizeof(u64);
                namelen = ceph_decode_32(p);  /* skip mds name */
                *p += namelen;

                ceph_decode_32_safe(p, end, mds, bad);
                ceph_decode_32_safe(p, end, inc, bad);
                ceph_decode_32_safe(p, end, state, bad);
                *p += sizeof(u64);              /* state_seq */
                if (info_v >= 8)
                        err = ceph_decode_entity_addrvec(p, end, msgr2, &addr);
                else
                        err = ceph_decode_entity_addr(p, end, &addr);
                if (err)
                        goto corrupt;

                ceph_decode_copy_safe(p, end, &laggy_since, sizeof(laggy_since),
                                      bad);
                laggy = laggy_since.tv_sec != 0 || laggy_since.tv_nsec != 0;
                *p += sizeof(u32);
                ceph_decode_32_safe(p, end, namelen, bad);
                *p += namelen;
                if (info_v >= 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;
                }

                if (info_end && *p != info_end) {
                        if (*p > info_end)
                                goto bad;
                        *p = info_end;
                }

                doutc(cl, "%d/%d %lld mds%d.%d %s %s%s\n", i+1, n, global_id,
                      mds, inc, ceph_pr_addr(&addr),
                      ceph_mds_state_name(state), laggy ? "(laggy)" : "");

                if (mds < 0 || mds >= m->possible_max_rank) {
                        pr_warn_client(cl, "got incorrect mds(%d)\n", mds);
                        continue;
                }

                if (state <= 0) {
                        doutc(cl, "got incorrect state(%s)\n",
                              ceph_mds_state_name(state));
                        continue;
                }

                info = &m->m_info[mds];
                info->global_id = global_id;
                info->state = state;
                info->addr = addr;
                info->laggy = laggy;
                info->num_export_targets = num_export_targets;
                if (num_export_targets) {
                        info->export_targets = kcalloc(num_export_targets,
                                                       sizeof(u32), GFP_NOFS);
                        if (!info->export_targets)
                                goto nomem;
                        for (j = 0; j < num_export_targets; j++) {
                                target = ceph_decode_32(&pexport_targets);
                                info->export_targets[j] = target;
                        }
                } else {
                        info->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(u64), GFP_NOFS);
        if (!m->m_data_pg_pools)
                goto nomem;
        ceph_decode_need(p, end, sizeof(u64)*(n+1), bad);
        for (i = 0; i < n; i++)
                m->m_data_pg_pools[i] = ceph_decode_64(p);
        m->m_cas_pg_pool = ceph_decode_64(p);
        m->m_enabled = m->m_epoch > 1;

        mdsmap_ev = 1;
        if (mdsmap_v >= 2) {
                ceph_decode_16_safe(p, end, mdsmap_ev, bad_ext);
        }
        if (mdsmap_ev >= 3) {
                if (__decode_and_drop_compat_set(p, end) < 0)
                        goto bad_ext;
        }
        /* metadata_pool */
        if (mdsmap_ev < 5) {
                __decode_and_drop_type(p, end, u32, bad_ext);
        } else {
                __decode_and_drop_type(p, end, u64, bad_ext);
        }

        /* created + modified + tableserver */
        __decode_and_drop_type(p, end, struct ceph_timespec, bad_ext);
        __decode_and_drop_type(p, end, struct ceph_timespec, bad_ext);
        __decode_and_drop_type(p, end, u32, bad_ext);

        /* in */
        {
                int num_laggy = 0;
                ceph_decode_32_safe(p, end, n, bad_ext);
                ceph_decode_need(p, end, sizeof(u32) * n, bad_ext);

                for (i = 0; i < n; i++) {
                        s32 mds = ceph_decode_32(p);
                        if (mds >= 0 && mds < m->possible_max_rank) {
                                if (m->m_info[mds].laggy)
                                        num_laggy++;
                        }
                }
                m->m_num_laggy = num_laggy;

                if (n > m->possible_max_rank) {
                        void *new_m_info = krealloc(m->m_info,
                                                    n * sizeof(*m->m_info),
                                                    GFP_NOFS | __GFP_ZERO);
                        if (!new_m_info)
                                goto nomem;
                        m->m_info = new_m_info;
                }
                m->possible_max_rank = n;
        }

        /* inc */
        __decode_and_drop_map(p, end, u32, u32, bad_ext);
        /* up */
        __decode_and_drop_map(p, end, u32, u64, bad_ext);
        /* failed */
        __decode_and_drop_set(p, end, u32, bad_ext);
        /* stopped */
        __decode_and_drop_set(p, end, u32, bad_ext);

        if (mdsmap_ev >= 4) {
                /* last_failure_osd_epoch */
                __decode_and_drop_type(p, end, u32, bad_ext);
        }
        if (mdsmap_ev >= 6) {
                /* ever_allowed_snaps */
                __decode_and_drop_type(p, end, u8, bad_ext);
                /* explicitly_allowed_snaps */
                __decode_and_drop_type(p, end, u8, bad_ext);
        }
        if (mdsmap_ev >= 7) {
                /* inline_data_enabled */
                __decode_and_drop_type(p, end, u8, bad_ext);
        }
        if (mdsmap_ev >= 8) {
                size_t fsname_len;

                /* enabled */
                ceph_decode_8_safe(p, end, m->m_enabled, bad_ext);

                /* fs_name */
                m->m_fs_name = ceph_extract_encoded_string(p, end,
                                                           &fsname_len,
                                                           GFP_NOFS);
                if (IS_ERR(m->m_fs_name)) {
                        m->m_fs_name = NULL;
                        goto nomem;
                }

                /* validate fsname against mds_namespace */
                if (!namespace_equals(mdsc->fsc->mount_options, m->m_fs_name,
                                      fsname_len)) {
                        pr_warn_client(cl, "fsname %s doesn't match mds_namespace %s\n",
                                       m->m_fs_name,
                                       mdsc->fsc->mount_options->mds_namespace);
                        goto bad;
                }
        } else {
                m->m_enabled = false;
                m->m_fs_name = kstrdup(CEPH_OLD_FS_NAME, GFP_NOFS);
                if (!m->m_fs_name)
                        goto nomem;
        }
        /* damaged */
        if (mdsmap_ev >= 9) {
                size_t need;
                ceph_decode_32_safe(p, end, n, bad_ext);
                need = sizeof(u32) * n;
                ceph_decode_need(p, end, need, bad_ext);
                *p += need;
                m->m_damaged = n > 0;
        } else {
                m->m_damaged = false;
        }
        if (mdsmap_ev >= 17) {
                /* balancer */
                ceph_decode_skip_string(p, end, bad_ext);
                /* standby_count_wanted */
                ceph_decode_skip_32(p, end, bad_ext);
                /* old_max_mds */
                ceph_decode_skip_32(p, end, bad_ext);
                /* min_compat_client */
                ceph_decode_skip_8(p, end, bad_ext);
                /* required_client_features */
                ceph_decode_skip_set(p, end, 64, bad_ext);
                /* bal_rank_mask */
                ceph_decode_skip_string(p, end, bad_ext);
        }
        if (mdsmap_ev >= 18) {
                ceph_decode_64_safe(p, end, m->m_max_xattr_size, bad_ext);
        }
bad_ext:
        doutc(cl, "m_enabled: %d, m_damaged: %d, m_num_laggy: %d\n",
              !!m->m_enabled, !!m->m_damaged, m->m_num_laggy);
        *p = end;
        doutc(cl, "success epoch %u\n", m->m_epoch);
        return m;
nomem:
        err = -ENOMEM;
        goto out_err;
corrupt:
        pr_err_client(cl, "corrupt mdsmap\n");
        print_hex_dump(KERN_DEBUG, "mdsmap: ",
                       DUMP_PREFIX_OFFSET, 16, 1,
                       start, end - start, true);
out_err:
        ceph_mdsmap_destroy(m);
        return ERR_PTR(err);
bad:
        err = -EINVAL;
        goto corrupt;
}

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

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

bool ceph_mdsmap_is_cluster_available(struct ceph_mdsmap *m)
{
        int i, nr_active = 0;
        if (!m->m_enabled)
                return false;
        if (m->m_damaged)
                return false;
        if (m->m_num_laggy == m->m_num_active_mds)
                return false;
        for (i = 0; i < m->possible_max_rank; i++) {
                if (m->m_info[i].state == CEPH_MDS_STATE_ACTIVE)
                        nr_active++;
        }
        return nr_active > 0;
}