Archipelago » qemu

/*

 * QEMU Block driver for RADOS (Ceph)

 *

 * Copyright (C) 2010 Christian Brunner <chb@muc.de>

 *

 * This work is licensed under the terms of the GNU GPL, version 2.  See

 * the COPYING file in the top-level directory.

 *

 */

#include "qemu-common.h"

#include "qemu-error.h"

#include "rbd_types.h"

#include "block_int.h"

#include <rados/librados.h>

/*

 * When specifying the image filename use:

 *

 * rbd:poolname/devicename

 *

 * poolname must be the name of an existing rados pool

 *

 * devicename is the basename for all objects used to

 * emulate the raw device.

 *

 * Metadata information (image size, ...) is stored in an

 * object with the name "devicename.rbd".

 *

 * The raw device is split into 4MB sized objects by default.

 * The sequencenumber is encoded in a 12 byte long hex-string,

 * and is attached to the devicename, separated by a dot.

 * e.g. "devicename.1234567890ab"

 *

 */

#define OBJ_MAX_SIZE (1UL << OBJ_DEFAULT_OBJ_ORDER)

typedef struct RBDAIOCB {

    BlockDriverAIOCB common;

    QEMUBH *bh;

    int ret;

    QEMUIOVector *qiov;

    char *bounce;

    int write;

    int64_t sector_num;

    int aiocnt;

    int error;

    struct BDRVRBDState *s;

    int cancelled;

} RBDAIOCB;

typedef struct RADOSCB {

    int rcbid;

    RBDAIOCB *acb;

    struct BDRVRBDState *s;

    int done;

    int64_t segsize;

    char *buf;

    int ret;

} RADOSCB;

#define RBD_FD_READ 0

#define RBD_FD_WRITE 1

typedef struct BDRVRBDState {

    int fds[2];

    rados_pool_t pool;

    rados_pool_t header_pool;

    char name[RBD_MAX_OBJ_NAME_SIZE];

    char block_name[RBD_MAX_BLOCK_NAME_SIZE];

    uint64_t size;

    uint64_t objsize;

    int qemu_aio_count;

    int event_reader_pos;

    RADOSCB *event_rcb;

} BDRVRBDState;

typedef struct rbd_obj_header_ondisk RbdHeader1;

static void rbd_aio_bh_cb(void *opaque);

static int rbd_next_tok(char *dst, int dst_len,

                        char *src, char delim,

                        const char *name,

                        char **p)

{

    int l;

    char *end;

    *p = NULL;

    if (delim != '\0') {

        end = strchr(src, delim);

        if (end) {

            *p = end + 1;

            *end = '\0';

        }

    }

    l = strlen(src);

    if (l >= dst_len) {

        error_report("%s too long", name);

        return -EINVAL;

    } else if (l == 0) {

        error_report("%s too short", name);

        return -EINVAL;

    }

    pstrcpy(dst, dst_len, src);

    return 0;

}

static int rbd_parsename(const char *filename,

                         char *pool, int pool_len,

                         char *snap, int snap_len,

                         char *name, int name_len)

{

    const char *start;

    char *p, *buf;

    int ret;

    if (!strstart(filename, "rbd:", &start)) {

        return -EINVAL;

    }

    buf = qemu_strdup(start);

    p = buf;

    ret = rbd_next_tok(pool, pool_len, p, '/', "pool name", &p);

    if (ret < 0 || !p) {

        ret = -EINVAL;

        goto done;

    }

    ret = rbd_next_tok(name, name_len, p, '@', "object name", &p);

    if (ret < 0) {

        goto done;

    }

    if (!p) {

        *snap = '\0';

        goto done;

    }

    ret = rbd_next_tok(snap, snap_len, p, '\0', "snap name", &p);

done:

    qemu_free(buf);

    return ret;

}

static int create_tmap_op(uint8_t op, const char *name, char **tmap_desc)

{

    uint32_t len = strlen(name);

    uint32_t len_le = cpu_to_le32(len);

    /* total_len = encoding op + name + empty buffer */

    uint32_t total_len = 1 + (sizeof(uint32_t) + len) + sizeof(uint32_t);

    uint8_t *desc = NULL;

    desc = qemu_malloc(total_len);

    *tmap_desc = (char *)desc;

    *desc = op;

    desc++;

    memcpy(desc, &len_le, sizeof(len_le));

    desc += sizeof(len_le);

    memcpy(desc, name, len);

    desc += len;

    len = 0; /* no need for endian conversion for 0 */

    memcpy(desc, &len, sizeof(len));

    desc += sizeof(len);

    return (char *)desc - *tmap_desc;

}

static void free_tmap_op(char *tmap_desc)

{

    qemu_free(tmap_desc);

}

static int rbd_register_image(rados_pool_t pool, const char *name)

{

    char *tmap_desc;

    const char *dir = RBD_DIRECTORY;

    int ret;

    ret = create_tmap_op(CEPH_OSD_TMAP_SET, name, &tmap_desc);

    if (ret < 0) {

        return ret;

    }

    ret = rados_tmap_update(pool, dir, tmap_desc, ret);

    free_tmap_op(tmap_desc);

    return ret;

}

static int touch_rbd_info(rados_pool_t pool, const char *info_oid)

{

    int r = rados_write(pool, info_oid, 0, NULL, 0);

    if (r < 0) {

        return r;

    }

    return 0;

}

static int rbd_assign_bid(rados_pool_t pool, uint64_t *id)

{

    uint64_t out[1];

    const char *info_oid = RBD_INFO;

    *id = 0;

    int r = touch_rbd_info(pool, info_oid);

    if (r < 0) {

        return r;

    }

    r = rados_exec(pool, info_oid, "rbd", "assign_bid", NULL,

                   0, (char *)out, sizeof(out));

    if (r < 0) {

        return r;

    }

    le64_to_cpus(out);

    *id = out[0];

    return 0;

}

static int rbd_create(const char *filename, QEMUOptionParameter *options)

{

    int64_t bytes = 0;

    int64_t objsize;

    uint64_t size;

    time_t mtime;

    uint8_t obj_order = RBD_DEFAULT_OBJ_ORDER;

    char pool[RBD_MAX_SEG_NAME_SIZE];

    char n[RBD_MAX_SEG_NAME_SIZE];

    char name[RBD_MAX_OBJ_NAME_SIZE];

    char snap_buf[RBD_MAX_SEG_NAME_SIZE];

    char *snap = NULL;

    RbdHeader1 header;

    rados_pool_t p;

    uint64_t bid;

    uint32_t hi, lo;

    int ret;

    if (rbd_parsename(filename,

                      pool, sizeof(pool),

                      snap_buf, sizeof(snap_buf),

                      name, sizeof(name)) < 0) {

        return -EINVAL;

    }

    if (snap_buf[0] != '\0') {

        snap = snap_buf;

    }

    snprintf(n, sizeof(n), "%s%s", name, RBD_SUFFIX);

    /* Read out options */

    while (options && options->name) {

        if (!strcmp(options->name, BLOCK_OPT_SIZE)) {

            bytes = options->value.n;

        } else if (!strcmp(options->name, BLOCK_OPT_CLUSTER_SIZE)) {

            if (options->value.n) {

                objsize = options->value.n;

                if ((objsize - 1) & objsize) {    /* not a power of 2? */

                    error_report("obj size needs to be power of 2");

                    return -EINVAL;

                }

                if (objsize < 4096) {

                    error_report("obj size too small");

                    return -EINVAL;

                }

                obj_order = ffs(objsize) - 1;

            }

        }

        options++;

    }

    memset(&header, 0, sizeof(header));

    pstrcpy(header.text, sizeof(header.text), RBD_HEADER_TEXT);

    pstrcpy(header.signature, sizeof(header.signature), RBD_HEADER_SIGNATURE);

    pstrcpy(header.version, sizeof(header.version), RBD_HEADER_VERSION);

    header.image_size = cpu_to_le64(bytes);

    header.options.order = obj_order;

    header.options.crypt_type = RBD_CRYPT_NONE;

    header.options.comp_type = RBD_COMP_NONE;

    header.snap_seq = 0;

    header.snap_count = 0;

    if (rados_initialize(0, NULL) < 0) {

        error_report("error initializing");

        return -EIO;

    }

    if (rados_open_pool(pool, &p)) {

        error_report("error opening pool %s", pool);

        rados_deinitialize();

        return -EIO;

    }

    /* check for existing rbd header file */

    ret = rados_stat(p, n, &size, &mtime);

    if (ret == 0) {

        ret=-EEXIST;

        goto done;

    }

    ret = rbd_assign_bid(p, &bid);

    if (ret < 0) {

        error_report("failed assigning block id");

        rados_deinitialize();

        return -EIO;

    }

    hi = bid >> 32;

    lo = bid & 0xFFFFFFFF;

    snprintf(header.block_name, sizeof(header.block_name), "rb.%x.%x", hi, lo);

    /* create header file */

    ret = rados_write(p, n, 0, (const char *)&header, sizeof(header));

    if (ret < 0) {

        goto done;

    }

    ret = rbd_register_image(p, name);

done:

    rados_close_pool(p);

    rados_deinitialize();

    return ret;

}

/*

 * This aio completion is being called from rbd_aio_event_reader() and

 * runs in qemu context. It schedules a bh, but just in case the aio

 * was not cancelled before.

 */

static void rbd_complete_aio(RADOSCB *rcb)

{

    RBDAIOCB *acb = rcb->acb;

    int64_t r;

    acb->aiocnt--;

    if (acb->cancelled) {

        if (!acb->aiocnt) {

            qemu_vfree(acb->bounce);

            qemu_aio_release(acb);

        }

        goto done;

    }

    r = rcb->ret;

    if (acb->write) {

        if (r < 0) {

            acb->ret = r;

            acb->error = 1;

        } else if (!acb->error) {

            acb->ret += rcb->segsize;

        }

    } else {

        if (r == -ENOENT) {

            memset(rcb->buf, 0, rcb->segsize);

            if (!acb->error) {

                acb->ret += rcb->segsize;

            }

        } else if (r < 0) {

            memset(rcb->buf, 0, rcb->segsize);

            acb->ret = r;

            acb->error = 1;

        } else if (r < rcb->segsize) {

            memset(rcb->buf + r, 0, rcb->segsize - r);

            if (!acb->error) {

                acb->ret += rcb->segsize;

            }

        } else if (!acb->error) {

            acb->ret += r;

        }

    }

    /* Note that acb->bh can be NULL in case where the aio was cancelled */

    if (!acb->aiocnt) {

        acb->bh = qemu_bh_new(rbd_aio_bh_cb, acb);

        qemu_bh_schedule(acb->bh);

    }

done:

    qemu_free(rcb);

}

/*

 * aio fd read handler. It runs in the qemu context and calls the

 * completion handling of completed rados aio operations.

 */

static void rbd_aio_event_reader(void *opaque)

{

    BDRVRBDState *s = opaque;

    ssize_t ret;

    do {

        char *p = (char *)&s->event_rcb;

        /* now read the rcb pointer that was sent from a non qemu thread */

        if ((ret = read(s->fds[RBD_FD_READ], p + s->event_reader_pos,

                        sizeof(s->event_rcb) - s->event_reader_pos)) > 0) {

            if (ret > 0) {

                s->event_reader_pos += ret;

                if (s->event_reader_pos == sizeof(s->event_rcb)) {

                    s->event_reader_pos = 0;

                    rbd_complete_aio(s->event_rcb);

                    s->qemu_aio_count --;

                }

            }

        }

    } while (ret < 0 && errno == EINTR);

}

static int rbd_aio_flush_cb(void *opaque)

{

    BDRVRBDState *s = opaque;

    return (s->qemu_aio_count > 0);

}

static int rbd_set_snapc(rados_pool_t pool, const char *snap, RbdHeader1 *header)

{

    uint32_t snap_count = le32_to_cpu(header->snap_count);

    rados_snap_t *snaps = NULL;

    rados_snap_t seq;

    uint32_t i;

    uint64_t snap_names_len = le64_to_cpu(header->snap_names_len);

    int r;

    rados_snap_t snapid = 0;

    if (snap_count) {

        const char *header_snap = (const char *)&header->snaps[snap_count];

        const char *end = header_snap + snap_names_len;

        snaps = qemu_malloc(sizeof(rados_snap_t) * header->snap_count);

        for (i=0; i < snap_count; i++) {

            snaps[i] = le64_to_cpu(header->snaps[i].id);

            if (snap && strcmp(snap, header_snap) == 0) {

                snapid = snaps[i];

            }

            header_snap += strlen(header_snap) + 1;

            if (header_snap > end) {

                error_report("bad header, snapshot list broken");

            }

        }

    }

    if (snap && !snapid) {

        error_report("snapshot not found");

        qemu_free(snaps);

        return -ENOENT;

    }

    seq = le32_to_cpu(header->snap_seq);

    r = rados_set_snap_context(pool, seq, snaps, snap_count);

    rados_set_snap(pool, snapid);

    qemu_free(snaps);

    return r;

}

#define BUF_READ_START_LEN    4096

static int rbd_read_header(BDRVRBDState *s, char **hbuf)

{

    char *buf = NULL;

    char n[RBD_MAX_SEG_NAME_SIZE];

    uint64_t len = BUF_READ_START_LEN;

    int r;

    snprintf(n, sizeof(n), "%s%s", s->name, RBD_SUFFIX);

    buf = qemu_malloc(len);

    r = rados_read(s->header_pool, n, 0, buf, len);

    if (r < 0) {

        goto failed;

    }

    if (r < len) {

        goto done;

    }

    qemu_free(buf);

    buf = qemu_malloc(len);

    r = rados_stat(s->header_pool, n, &len, NULL);

    if (r < 0) {

        goto failed;

    }

    r = rados_read(s->header_pool, n, 0, buf, len);

    if (r < 0) {

        goto failed;

    }

done:

    *hbuf = buf;

    return 0;

failed:

    qemu_free(buf);

    return r;

}

static int rbd_open(BlockDriverState *bs, const char *filename, int flags)

{

    BDRVRBDState *s = bs->opaque;

    RbdHeader1 *header;

    char pool[RBD_MAX_SEG_NAME_SIZE];

    char snap_buf[RBD_MAX_SEG_NAME_SIZE];

    char *snap = NULL;

    char *hbuf = NULL;

    int r;

    if (rbd_parsename(filename, pool, sizeof(pool),

                      snap_buf, sizeof(snap_buf),

                      s->name, sizeof(s->name)) < 0) {

        return -EINVAL;

    }

    if (snap_buf[0] != '\0') {

        snap = snap_buf;

    }

    if ((r = rados_initialize(0, NULL)) < 0) {

        error_report("error initializing");

        return r;

    }

    if ((r = rados_open_pool(pool, &s->pool))) {

        error_report("error opening pool %s", pool);

        rados_deinitialize();

        return r;

    }

    if ((r = rados_open_pool(pool, &s->header_pool))) {

        error_report("error opening pool %s", pool);

        rados_deinitialize();

        return r;

    }

    if ((r = rbd_read_header(s, &hbuf)) < 0) {

        error_report("error reading header from %s", s->name);

        goto failed;

    }

    if (memcmp(hbuf + 64, RBD_HEADER_SIGNATURE, 4)) {

        error_report("Invalid header signature");

        r = -EMEDIUMTYPE;

        goto failed;

    }

    if (memcmp(hbuf + 68, RBD_HEADER_VERSION, 8)) {

        error_report("Unknown image version");

        r = -EMEDIUMTYPE;

        goto failed;

    }

    header = (RbdHeader1 *) hbuf;

    s->size = le64_to_cpu(header->image_size);

    s->objsize = 1ULL << header->options.order;

    memcpy(s->block_name, header->block_name, sizeof(header->block_name));

    r = rbd_set_snapc(s->pool, snap, header);

    if (r < 0) {

        error_report("failed setting snap context: %s", strerror(-r));

        goto failed;

    }

    bs->read_only = (snap != NULL);

    s->event_reader_pos = 0;

    r = qemu_pipe(s->fds);

    if (r < 0) {

        error_report("error opening eventfd");

        goto failed;

    }

    fcntl(s->fds[0], F_SETFL, O_NONBLOCK);

    fcntl(s->fds[1], F_SETFL, O_NONBLOCK);

    qemu_aio_set_fd_handler(s->fds[RBD_FD_READ], rbd_aio_event_reader, NULL,

        rbd_aio_flush_cb, NULL, s);

    qemu_free(hbuf);

    return 0;

failed:

    qemu_free(hbuf);

    rados_close_pool(s->header_pool);

    rados_close_pool(s->pool);

    rados_deinitialize();

    return r;

}

static void rbd_close(BlockDriverState *bs)

{

    BDRVRBDState *s = bs->opaque;

    close(s->fds[0]);

    close(s->fds[1]);

    qemu_aio_set_fd_handler(s->fds[RBD_FD_READ], NULL , NULL, NULL, NULL,

        NULL);

    rados_close_pool(s->header_pool);

    rados_close_pool(s->pool);

    rados_deinitialize();

}

/*

 * Cancel aio. Since we don't reference acb in a non qemu threads,

 * it is safe to access it here.

 */

static void rbd_aio_cancel(BlockDriverAIOCB *blockacb)

{

    RBDAIOCB *acb = (RBDAIOCB *) blockacb;

    acb->cancelled = 1;

}

static AIOPool rbd_aio_pool = {

    .aiocb_size = sizeof(RBDAIOCB),

    .cancel = rbd_aio_cancel,

};

/*

 * This is the callback function for rados_aio_read and _write

 *

 * Note: this function is being called from a non qemu thread so

 * we need to be careful about what we do here. Generally we only

 * write to the block notification pipe, and do the rest of the

 * io completion handling from rbd_aio_event_reader() which

 * runs in a qemu context.

 */

static void rbd_finish_aiocb(rados_completion_t c, RADOSCB *rcb)

{

    int ret;

    rcb->ret = rados_aio_get_return_value(c);

    rados_aio_release(c);

    while (1) {

        fd_set wfd;

        int fd = rcb->s->fds[RBD_FD_WRITE];

        /* send the rcb pointer to the qemu thread that is responsible

           for the aio completion. Must do it in a qemu thread context */

        ret = write(fd, (void *)&rcb, sizeof(rcb));

        if (ret >= 0) {

            break;

        }

        if (errno == EINTR) {

            continue;

        }

        if (errno != EAGAIN) {

            break;

        }

        FD_ZERO(&wfd);

        FD_SET(fd, &wfd);

        do {

            ret = select(fd + 1, NULL, &wfd, NULL, NULL);

        } while (ret < 0 && errno == EINTR);

    }

    if (ret < 0) {

        error_report("failed writing to acb->s->fds\n");

        qemu_free(rcb);

    }

}

/* Callback when all queued rados_aio requests are complete */

static void rbd_aio_bh_cb(void *opaque)

{

    RBDAIOCB *acb = opaque;

    if (!acb->write) {

        qemu_iovec_from_buffer(acb->qiov, acb->bounce, acb->qiov->size);

    }

    qemu_vfree(acb->bounce);

    acb->common.cb(acb->common.opaque, (acb->ret > 0 ? 0 : acb->ret));

    qemu_bh_delete(acb->bh);

    acb->bh = NULL;

    qemu_aio_release(acb);

}

static BlockDriverAIOCB *rbd_aio_rw_vector(BlockDriverState *bs,

                                           int64_t sector_num,

                                           QEMUIOVector *qiov,

                                           int nb_sectors,

                                           BlockDriverCompletionFunc *cb,

                                           void *opaque, int write)

{

    RBDAIOCB *acb;

    RADOSCB *rcb;

    rados_completion_t c;

    char n[RBD_MAX_SEG_NAME_SIZE];

    int64_t segnr, segoffs, segsize, last_segnr;

    int64_t off, size;

    char *buf;

    BDRVRBDState *s = bs->opaque;

    acb = qemu_aio_get(&rbd_aio_pool, bs, cb, opaque);

    acb->write = write;

    acb->qiov = qiov;

    acb->bounce = qemu_blockalign(bs, qiov->size);

    acb->aiocnt = 0;

    acb->ret = 0;

    acb->error = 0;

    acb->s = s;

    acb->cancelled = 0;

    acb->bh = NULL;

    if (write) {

        qemu_iovec_to_buffer(acb->qiov, acb->bounce);

    }

    buf = acb->bounce;

    off = sector_num * BDRV_SECTOR_SIZE;

    size = nb_sectors * BDRV_SECTOR_SIZE;

    segnr = off / s->objsize;

    segoffs = off % s->objsize;

    segsize = s->objsize - segoffs;

    last_segnr = ((off + size - 1) / s->objsize);

    acb->aiocnt = (last_segnr - segnr) + 1;

    s->qemu_aio_count += acb->aiocnt; /* All the RADOSCB */

    while (size > 0) {

        if (size < segsize) {

            segsize = size;

        }

        snprintf(n, sizeof(n), "%s.%012" PRIx64, s->block_name,

                 segnr);

        rcb = qemu_malloc(sizeof(RADOSCB));

        rcb->done = 0;

        rcb->acb = acb;

        rcb->segsize = segsize;

        rcb->buf = buf;

        rcb->s = acb->s;

        if (write) {

            rados_aio_create_completion(rcb, NULL,

                                        (rados_callback_t) rbd_finish_aiocb,

                                        &c);

            rados_aio_write(s->pool, n, segoffs, buf, segsize, c);

        } else {

            rados_aio_create_completion(rcb,

                                        (rados_callback_t) rbd_finish_aiocb,

                                        NULL, &c);

            rados_aio_read(s->pool, n, segoffs, buf, segsize, c);

        }

        buf += segsize;

        size -= segsize;

        segoffs = 0;

        segsize = s->objsize;

        segnr++;

    }

    return &acb->common;

}

static BlockDriverAIOCB *rbd_aio_readv(BlockDriverState * bs,

                                       int64_t sector_num, QEMUIOVector * qiov,

                                       int nb_sectors,

                                       BlockDriverCompletionFunc * cb,

                                       void *opaque)

{

    return rbd_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 0);

}

static BlockDriverAIOCB *rbd_aio_writev(BlockDriverState * bs,

                                        int64_t sector_num, QEMUIOVector * qiov,

                                        int nb_sectors,

                                        BlockDriverCompletionFunc * cb,

                                        void *opaque)

{

    return rbd_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 1);

}

static int rbd_getinfo(BlockDriverState * bs, BlockDriverInfo * bdi)

{

    BDRVRBDState *s = bs->opaque;

    bdi->cluster_size = s->objsize;

    return 0;

}

static int64_t rbd_getlength(BlockDriverState * bs)

{

    BDRVRBDState *s = bs->opaque;

    return s->size;

}

static int rbd_snap_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)

{

    BDRVRBDState *s = bs->opaque;

    char inbuf[512], outbuf[128];

    uint64_t snap_id;

    int r;

    char *p = inbuf;

    char *end = inbuf + sizeof(inbuf);

    char n[RBD_MAX_SEG_NAME_SIZE];

    char *hbuf = NULL;

    RbdHeader1 *header;

    if (sn_info->name[0] == '\0') {

        return -EINVAL; /* we need a name for rbd snapshots */

    }

    /*

     * rbd snapshots are using the name as the user controlled unique identifier

     * we can't use the rbd snapid for that purpose, as it can't be set

     */

    if (sn_info->id_str[0] != '\0' &&

        strcmp(sn_info->id_str, sn_info->name) != 0) {

        return -EINVAL;

    }

    if (strlen(sn_info->name) >= sizeof(sn_info->id_str)) {

        return -ERANGE;

    }

    r = rados_selfmanaged_snap_create(s->header_pool, &snap_id);

    if (r < 0) {

        error_report("failed to create snap id: %s", strerror(-r));

        return r;

    }

    *(uint32_t *)p = strlen(sn_info->name);

    cpu_to_le32s((uint32_t *)p);

    p += sizeof(uint32_t);

    strncpy(p, sn_info->name, end - p);

    p += strlen(p);

    if (p + sizeof(snap_id) > end) {

        error_report("invalid input parameter");

        return -EINVAL;

    }

    *(uint64_t *)p = snap_id;

    cpu_to_le64s((uint64_t *)p);

    snprintf(n, sizeof(n), "%s%s", s->name, RBD_SUFFIX);

    r = rados_exec(s->header_pool, n, "rbd", "snap_add", inbuf,

                   sizeof(inbuf), outbuf, sizeof(outbuf));

    if (r < 0) {

        error_report("rbd.snap_add execution failed failed: %s", strerror(-r));

        return r;

    }

    sprintf(sn_info->id_str, "%s", sn_info->name);

    r = rbd_read_header(s, &hbuf);

    if (r < 0) {

        error_report("failed reading header: %s", strerror(-r));

        return r;

    }

    header = (RbdHeader1 *) hbuf;

    r = rbd_set_snapc(s->pool, sn_info->name, header);

    if (r < 0) {

        error_report("failed setting snap context: %s", strerror(-r));

        goto failed;

    }

    return 0;

failed:

    qemu_free(header);

    return r;

}

static int decode32(char **p, const char *end, uint32_t *v)

{

    if (*p + 4 > end) {

        return -ERANGE;

    }

    *v = *(uint32_t *)(*p);

    le32_to_cpus(v);

    *p += 4;

    return 0;

}

static int decode64(char **p, const char *end, uint64_t *v)

{

    if (*p + 8 > end) {

        return -ERANGE;

    }

    *v = *(uint64_t *)(*p);

    le64_to_cpus(v);

    *p += 8;

    return 0;

}

static int decode_str(char **p, const char *end, char **s)

{

    uint32_t len;

    int r;

    if ((r = decode32(p, end, &len)) < 0) {

        return r;

    }

    *s = qemu_malloc(len + 1);

    memcpy(*s, *p, len);

    *p += len;

    (*s)[len] = '\0';

    return len;

}

static int rbd_snap_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)

{

    BDRVRBDState *s = bs->opaque;

    char n[RBD_MAX_SEG_NAME_SIZE];

    QEMUSnapshotInfo *sn_info, *sn_tab = NULL;

    RbdHeader1 *header;

    char *hbuf = NULL;

    char *outbuf = NULL, *end, *buf;

    uint64_t len;

    uint64_t snap_seq;

    uint32_t snap_count;

    int r, i;

    /* read header to estimate how much space we need to read the snap

     * list */

    if ((r = rbd_read_header(s, &hbuf)) < 0) {

        goto done_err;

    }

    header = (RbdHeader1 *)hbuf;

    len = le64_to_cpu(header->snap_names_len);

    len += 1024; /* should have already been enough, but new snapshots might

                    already been created since we read the header. just allocate

                    a bit more, so that in most cases it'll suffice anyway */

    qemu_free(hbuf);

    snprintf(n, sizeof(n), "%s%s", s->name, RBD_SUFFIX);

    while (1) {

        qemu_free(outbuf);

        outbuf = qemu_malloc(len);

        r = rados_exec(s->header_pool, n, "rbd", "snap_list", NULL, 0,

                       outbuf, len);

        if (r < 0) {

            error_report("rbd.snap_list execution failed failed: %s", strerror(-r));

            goto done_err;

        }

        if (r != len) {

            break;

        }

        /* if we're here, we probably raced with some snaps creation */

        len *= 2;

    }

    buf = outbuf;

    end = buf + len;

    if ((r = decode64(&buf, end, &snap_seq)) < 0) {

        goto done_err;

    }

    if ((r = decode32(&buf, end, &snap_count)) < 0) {

        goto done_err;

    }

    sn_tab = qemu_mallocz(snap_count * sizeof(QEMUSnapshotInfo));

    for (i = 0; i < snap_count; i++) {

        uint64_t id, image_size;

        char *snap_name;

        if ((r = decode64(&buf, end, &id)) < 0) {

            goto done_err;

        }

        if ((r = decode64(&buf, end, &image_size)) < 0) {

            goto done_err;

        }

        if ((r = decode_str(&buf, end, &snap_name)) < 0) {

            goto done_err;

        }

        sn_info = sn_tab + i;

        pstrcpy(sn_info->id_str, sizeof(sn_info->id_str), snap_name);

        pstrcpy(sn_info->name, sizeof(sn_info->name), snap_name);

        qemu_free(snap_name);

        sn_info->vm_state_size = image_size;

        sn_info->date_sec = 0;

        sn_info->date_nsec = 0;

        sn_info->vm_clock_nsec = 0;

    }

    *psn_tab = sn_tab;

    qemu_free(outbuf);

    return snap_count;

done_err:

    qemu_free(sn_tab);

    qemu_free(outbuf);

    return r;

}

static QEMUOptionParameter rbd_create_options[] = {

    {

     .name = BLOCK_OPT_SIZE,

     .type = OPT_SIZE,

     .help = "Virtual disk size"

    },

    {

     .name = BLOCK_OPT_CLUSTER_SIZE,

     .type = OPT_SIZE,

     .help = "RBD object size"

    },

    {NULL}

};

static BlockDriver bdrv_rbd = {

    .format_name        = "rbd",

    .instance_size      = sizeof(BDRVRBDState),

    .bdrv_file_open     = rbd_open,

    .bdrv_close         = rbd_close,

    .bdrv_create        = rbd_create,

    .bdrv_get_info      = rbd_getinfo,

    .create_options     = rbd_create_options,

    .bdrv_getlength     = rbd_getlength,

    .protocol_name      = "rbd",

    .bdrv_aio_readv     = rbd_aio_readv,

    .bdrv_aio_writev    = rbd_aio_writev,

    .bdrv_snapshot_create = rbd_snap_create,

    .bdrv_snapshot_list = rbd_snap_list,

};

static void bdrv_rbd_init(void)

{

    bdrv_register(&bdrv_rbd);

}

block_init(bdrv_rbd_init);