Re: [Qemu-devel] [PATCH 2/3] nbd: Add exports listing support.

[Paolo Bonzini <pbonzini@redhat.com>]

Il 31/05/2014 23:39, Hani Benhabiles ha scritto:
> This is added by handling the NBD_OPT_LIST and NBD_OPT_ABORT options.
>
> NBD_REP_ERR_UNSUP is also sent for unknown NBD option values.
>
> Signed-off-by: Hani Benhabiles <hani@linux.com>
> ---
>  include/block/nbd.h |   5 ++
>  nbd.c               | 197 +++++++++++++++++++++++++++++++++++++++++-----------
>  2 files changed, 162 insertions(+), 40 deletions(-)
>
> diff --git a/include/block/nbd.h b/include/block/nbd.h
> index 95d52ab..fd7e057 100644
> --- a/include/block/nbd.h
> +++ b/include/block/nbd.h
> @@ -51,6 +51,11 @@ struct nbd_reply {
>  /* New-style client flags. */
>  #define NBD_FLAG_C_FIXED_NEWSTYLE   (1 << 0)    /* Fixed newstyle protocol. */
>
> +/* Reply types. */
> +#define NBD_REP_ACK             (1)             /* Data sending finished. */
> +#define NBD_REP_SERVER          (2)             /* Export description. */
> +#define NBD_REP_ERR_UNSUP       ((1 << 31) | 1) /* Unknown option. */
> +
>  #define NBD_CMD_MASK_COMMAND	0x0000ffff
>  #define NBD_CMD_FLAG_FUA	(1 << 16)
>
> diff --git a/nbd.c b/nbd.c
> index aa2e552..012e5da 100644
> --- a/nbd.c
> +++ b/nbd.c
> @@ -64,6 +64,7 @@
>  #define NBD_REPLY_MAGIC         0x67446698
>  #define NBD_OPTS_MAGIC          0x49484156454F5054LL
>  #define NBD_CLIENT_MAGIC        0x0000420281861253LL
> +#define NBD_REP_MAGIC           0x3e889045565a9LL
>
>  #define NBD_SET_SOCK            _IO(0xab, 0)
>  #define NBD_SET_BLKSIZE         _IO(0xab, 1)
> @@ -77,7 +78,9 @@
>  #define NBD_SET_TIMEOUT         _IO(0xab, 9)
>  #define NBD_SET_FLAGS           _IO(0xab, 10)
>
> -#define NBD_OPT_EXPORT_NAME     (1 << 0)
> +#define NBD_OPT_EXPORT_NAME     (1)
> +#define NBD_OPT_ABORT           (2)
> +#define NBD_OPT_LIST            (3)
>
>  /* Definitions for opaque data types */
>
> @@ -215,54 +218,98 @@ static ssize_t write_sync(int fd, void *buffer, size_t size)
>
>  */
>
> -static int nbd_receive_options(NBDClient *client)
> +static int nbd_send_rep(int csock, uint32_t type, uint32_t opt)
>  {
> -    int csock = client->sock;
> -    char name[256];
> -    uint32_t tmp, length;
>      uint64_t magic;
> -    int rc;
> -
> -    /* Client sends:
> -        [ 0 ..   3]   client flags
> -        [ 4 ..  11]   NBD_OPTS_MAGIC
> -        [12 ..  15]   NBD_OPT_EXPORT_NAME
> -        [16 ..  19]   length
> -        [20 ..  xx]   export name (length bytes)
> -     */
> +    uint32_t len;
>
> -    rc = -EINVAL;
> -    if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
> -        LOG("read failed");
> -        goto fail;
> +    magic = cpu_to_be64(NBD_REP_MAGIC);
> +    if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
> +        LOG("write failed (rep magic)");
> +        return -EINVAL;
>      }
> -    TRACE("Checking client flags");
> -    tmp = be32_to_cpu(tmp);
> -    if (tmp != 0 && tmp != NBD_FLAG_C_FIXED_NEWSTYLE) {
> -        LOG("Bad client flags received");
> -        goto fail;
> +    opt = cpu_to_be32(opt);
> +    if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
> +        LOG("write failed (rep opt)");
> +        return -EINVAL;
>      }
> -
> -    if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
> -        LOG("read failed");
> -        goto fail;
> +    type = cpu_to_be32(type);
> +    if (write_sync(csock, &type, sizeof(type)) != sizeof(type)) {
> +        LOG("write failed (rep type)");
> +        return -EINVAL;
>      }
> -    TRACE("Checking opts magic");
> -    if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
> -        LOG("Bad magic received");
> -        goto fail;
> +    len = cpu_to_be32(0);
> +    if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
> +        LOG("write failed (rep data length)");
> +        return -EINVAL;
>      }
> +    return 0;
> +}
>
> -    if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
> -        LOG("read failed");
> -        goto fail;
> +static int nbd_send_rep_list(int csock, NBDExport *exp)
> +{
> +    uint64_t magic, name_len;
> +    uint32_t opt, type, len;
> +
> +    name_len = strlen(exp->name);
> +    magic = cpu_to_be64(NBD_REP_MAGIC);
> +    if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
> +        LOG("write failed (magic)");
> +        return -EINVAL;
>      }
> -    TRACE("Checking option");
> -    if (tmp != be32_to_cpu(NBD_OPT_EXPORT_NAME)) {
> -        LOG("Bad option received");
> -        goto fail;
> +    opt = cpu_to_be32(NBD_OPT_LIST);
> +    if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
> +        LOG("write failed (opt)");
> +        return -EINVAL;
> +    }
> +    type = cpu_to_be32(NBD_REP_SERVER);
> +    if (write_sync(csock, &type, sizeof(type)) != sizeof(type)) {
> +        LOG("write failed (reply type)");
> +        return -EINVAL;
> +    }
> +    len = cpu_to_be32(name_len + sizeof(len));
> +    if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
> +        LOG("write failed (length)");
> +        return -EINVAL;
> +    }
> +    len = cpu_to_be32(name_len);
> +    if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
> +        LOG("write failed (length)");
> +        return -EINVAL;
> +    }
> +    if (write_sync(csock, exp->name, name_len) != name_len) {
> +        LOG("write failed (buffer)");
> +        return -EINVAL;
> +    }
> +    return 0;
> +}
> +
> +static int nbd_send_list(NBDClient *client)
> +{
> +    int csock;
> +    NBDExport *exp;
> +
> +    csock = client->sock;
> +    /* For each export, send a NBD_REP_SERVER reply. */
> +    QTAILQ_FOREACH(exp, &exports, next) {
> +        if (nbd_send_rep_list(csock, exp)) {
> +            return -EINVAL;
> +        }
>      }
> +    /* Finish with a NBD_REP_ACK. */
> +    return nbd_send_rep(csock, NBD_REP_ACK, NBD_OPT_LIST);
> +}
> +
> +static int nbd_handle_export_name(NBDClient *client)
> +{
> +    int rc = -EINVAL, csock = client->sock;
> +    char name[256];
> +    uint32_t length;
>
> +    /* Client sends:
> +        [16 ..  19]   length
> +        [20 ..  xx]   export name (length bytes)
> +     */
>      if (read_sync(csock, &length, sizeof(length)) != sizeof(length)) {
>          LOG("read failed");
>          goto fail;
> @@ -287,8 +334,76 @@ static int nbd_receive_options(NBDClient *client)
>
>      QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
>      nbd_export_get(client->exp);
> +    rc = 0;
> +fail:
> +    return rc;
> +}
> +
> +static int nbd_receive_options(NBDClient *client)
> +{
> +    int rc = -EINVAL;
>
> -    TRACE("Option negotiation succeeded.");
> +    while (1) {
> +        int csock = client->sock;
> +        uint32_t tmp;
> +        uint64_t magic;
> +
> +        /* Client sends:
> +            [ 0 ..   3]   client flags
> +            [ 4 ..  11]   NBD_OPTS_MAGIC
> +            [12 ..  15]   NBD option
> +            ...           Rest of request
> +        */
> +
> +        if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
> +            LOG("read failed");
> +            goto fail;
> +        }
> +        TRACE("Checking client flags");
> +        tmp = be32_to_cpu(tmp);
> +        if (tmp != 0 && tmp != NBD_FLAG_C_FIXED_NEWSTYLE) {
> +            LOG("Bad client flags received");
> +            goto fail;
> +        }
> +
> +        if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
> +            LOG("read failed");
> +            goto fail;
> +        }
> +        TRACE("Checking opts magic");
> +        if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
> +            LOG("Bad magic received");
> +            goto fail;
> +        }
> +
> +        if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
> +            LOG("read failed");
> +            goto fail;
> +        }
> +
> +        TRACE("Checking option");
> +        switch (be32_to_cpu(tmp)) {
> +        case NBD_OPT_LIST:
> +            if (nbd_send_list(client) < 0) {
> +                return -EINVAL;
> +            }
> +            break;

You can just do "return nbd_send_list(client);" here.  You probably 
should also rename the function to nbd_handle_list.

> +        case NBD_OPT_ABORT:
> +            return 1;
> +
> +        case NBD_OPT_EXPORT_NAME:
> +            return nbd_handle_export_name(client);

Part of this patch belongs in patch 1.  This one should only add 
nbd_send_rep_list, nbd_handle_list and the NBD_OPT_LIST case.

Paolo

> +        default:
> +            tmp = be32_to_cpu(tmp);
> +            LOG("Unsupported option 0x%x", tmp);
> +            if (nbd_send_rep(client->sock, NBD_REP_ERR_UNSUP, tmp)) {
> +                return -EINVAL;
> +            }
> +            return 1;
> +        }
> +    }
>      rc = 0;
>  fail:
>      return rc;
> @@ -351,6 +466,8 @@ static int nbd_send_negotiate(NBDClient *client)
>          if (rc < 0) {
>              LOG("option negotiation failed");
>              goto fail;
> +        } else if (rc > 0) {
> +            goto fail;
>          }
>
>          assert ((client->exp->nbdflags & ~65535) == 0);
> @@ -1175,7 +1292,7 @@ NBDClient *nbd_client_new(NBDExport *exp, int csock,
>      client->refcount = 1;
>      client->exp = exp;
>      client->sock = csock;
> -    if (nbd_send_negotiate(client) < 0) {
> +    if (nbd_send_negotiate(client)) {
>          g_free(client);
>          return NULL;
>      }
>