mdsmap.c

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#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);
}