Re: [Qemu-devel] [PATCH] libiscsi

[Blue Swirl]

On Mon, Dec 13, 2010 at 8:05 AM, Ronnie Sahlberg
<address@hidden> wrote:
> This patch adds a new block driver : block.iscsi.c
> This driver interfaces with the multiplatform posix library
> for iscsi initiator/client access to iscsi devices hosted at
> git://github.com/sahlberg/libiscsi.git
>
> The patch adds the driver to interface with the iscsi library.
> It also updated the configure script to
> * by default, probe is libiscsi is available and if so, build
>  qemu against libiscsi.
> * --enable-libiscsi
>  Force a build against libiscsi. If libiscsi is not available
>  the build will fail.
> * --disable-libiscsi
>  Do not link against libiscsi, even if it is available.
>
> When linked with libiscsi, qemu gains support to access iscsi resources
> such as disks and cdrom directly, without having to make the devices visible
> to the host.
>
> You can specify devices using a iscsi url of the form :
> iscsi://<host>[:<port]/<target-iqn-name>/<lun>
>
> Example:
> -drive file=iscsi://10.1.1.1:3260/iqn.ronnie.test/1
>
> -cdrom iscsi://10.1.1.1:3260/iqn.ronnie.test/2
>
> Signed-off-by: Ronnie Sahlberg <address@hidden>
> ---
>  Makefile.objs |    2 +-
>  block/iscsi.c |  528 
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  configure     |   29 +++
>  3 files changed, 558 insertions(+), 1 deletions(-)
>  create mode 100644 block/iscsi.c
>
> diff --git a/Makefile.objs b/Makefile.objs
> index cebb945..81731c5 100644
> --- a/Makefile.objs
> +++ b/Makefile.objs
> @@ -22,7 +22,7 @@ block-nested-y += raw.o cow.o qcow.o vdi.o vmdk.o cloop.o 
> dmg.o bochs.o vpc.o vv
>  block-nested-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o
>  block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o
>  block-nested-$(CONFIG_WIN32) += raw-win32.o
> -block-nested-$(CONFIG_POSIX) += raw-posix.o
> +block-nested-$(CONFIG_POSIX) += raw-posix.o iscsi.o

Please use CONFIG_ISCSI...

>  block-nested-$(CONFIG_CURL) += curl.o
>
>  block-obj-y +=  $(addprefix block/, $(block-nested-y))
> diff --git a/block/iscsi.c b/block/iscsi.c
> new file mode 100644
> index 0000000..fba5ee6
> --- /dev/null
> +++ b/block/iscsi.c
> @@ -0,0 +1,528 @@
> +/*
> + * QEMU Block driver for iSCSI images
> + *
> + * Copyright (c) 2010 Ronnie Sahlberg <address@hidden>
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a 
> copy
> + * of this software and associated documentation files (the "Software"), to 
> deal
> + * in the Software without restriction, including without limitation the 
> rights
> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
> + * copies of the Software, and to permit persons to whom the Software is
> + * furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
> FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
> + * THE SOFTWARE.
> + */
> +
> +#include "config-host.h"
> +#ifdef CONFIG_LIBISCSI

... then this is not needed.

> +
> +#include <poll.h>
> +#include "sysemu.h"
> +#include "qemu-common.h"
> +#include "qemu-error.h"
> +#include "block_int.h"
> +
> +#include <iscsi/iscsi.h>
> +#include <iscsi/scsi-lowlevel.h>
> +
> +
> +typedef struct ISCSILUN {
> +    struct iscsi_context *iscsi;
> +    int lun;
> +    int block_size;
> +    unsigned long num_blocks;
> +} ISCSILUN;
> +
> +typedef struct ISCSIAIOCB {
> +    BlockDriverAIOCB common;
> +    QEMUIOVector *qiov;
> +    QEMUBH *bh;
> +    ISCSILUN *iscsilun;
> +    int canceled;
> +    int status;
> +    size_t read_size;
> +} ISCSIAIOCB;
> +
> +struct iscsi_task {
> +    ISCSILUN *iscsilun;
> +    int status;
> +    int complete;
> +};

Please see CODING_STYLE for struct naming and use of typedefs.

> +
> +static int
> +iscsi_is_inserted(BlockDriverState *bs)
> +{
> +    ISCSILUN *iscsilun = bs->opaque;
> +    struct iscsi_context *iscsi = iscsilun->iscsi;
> +
> +    return iscsi_is_logged_in(iscsi);
> +}
> +
> +
> +static void
> +iscsi_aio_cancel(BlockDriverAIOCB *blockacb)
> +{
> +    ISCSIAIOCB *acb = (ISCSIAIOCB *)blockacb;
> +
> +    acb->status = -EIO;
> +    acb->common.cb(acb->common.opaque, acb->status);
> +    acb->canceled = 1;
> +}
> +
> +static AIOPool iscsi_aio_pool = {
> +    .aiocb_size         = sizeof(ISCSIAIOCB),
> +    .cancel             = iscsi_aio_cancel,
> +};
> +
> +
> +static void iscsi_process_read(void *arg);
> +static void iscsi_process_write(void *arg);
> +
> +static void
> +iscsi_set_events(ISCSILUN *iscsilun)
> +{
> +    struct iscsi_context *iscsi = iscsilun->iscsi;
> +
> +    qemu_aio_set_fd_handler(iscsi_get_fd(iscsi), iscsi_process_read,
> +                           (iscsi_which_events(iscsi)&POLLOUT)

Please insert space around operators.

> +                           ?iscsi_process_write:NULL,

Also around ?:.

> +                           NULL, NULL, iscsilun);
> +}
> +
> +static void
> +iscsi_process_read(void *arg)
> +{
> +    ISCSILUN *iscsilun = arg;
> +    struct iscsi_context *iscsi = iscsilun->iscsi;
> +
> +    iscsi_service(iscsi, POLLIN);
> +    iscsi_set_events(iscsilun);
> +}
> +
> +static void
> +iscsi_process_write(void *arg)
> +{
> +    ISCSILUN *iscsilun = arg;
> +    struct iscsi_context *iscsi = iscsilun->iscsi;
> +
> +    iscsi_service(iscsi, POLLOUT);
> +    iscsi_set_events(iscsilun);
> +}
> +
> +
> +static int
> +iscsi_schedule_bh(QEMUBHFunc *cb, ISCSIAIOCB *acb)
> +{
> +    acb->bh = qemu_bh_new(cb, acb);
> +    if (!acb->bh) {
> +       error_report("oom: could not create iscsi bh");
> +       return -EIO;
> +    }
> +
> +    qemu_bh_schedule(acb->bh);
> +    return 0;
> +}
> +
> +static void
> +iscsi_readv_writev_bh_cb(void *p)
> +{
> +    ISCSIAIOCB *acb = p;
> +
> +    acb->common.cb(acb->common.opaque, acb->status);
> +    qemu_aio_release(acb);
> +}
> +
> +static void
> +iscsi_aio_write10_cb(struct iscsi_context *iscsi, int status,
> +                    void *command_data, void *private_data)
> +{
> +    ISCSIAIOCB *acb = private_data;
> +
> +    if (acb->canceled != 0) {
> +       qemu_aio_release(acb);
> +       return;
> +    }
> +
> +    acb->status = 0;
> +    if (status < 0) {
> +       error_report("Failed to write10 data to iSCSI lun. %s",
> +                    iscsi_get_error(iscsi));
> +       acb->status = -EIO;
> +    }
> +
> +    iscsi_schedule_bh(iscsi_readv_writev_bh_cb, acb);
> +}
> +
> +static BlockDriverAIOCB *
> +iscsi_aio_writev(BlockDriverState *bs, int64_t sector_num,
> +                QEMUIOVector *qiov, int nb_sectors,
> +                BlockDriverCompletionFunc *cb,
> +                void *opaque)
> +{
> +    ISCSILUN *iscsilun = bs->opaque;
> +    struct iscsi_context *iscsi = iscsilun->iscsi;
> +    ISCSIAIOCB *acb;
> +    size_t size;
> +    unsigned char *buf;

Why unsigned? Maybe uint8_t or plain char instead?

> +
> +    acb = qemu_aio_get(&iscsi_aio_pool, bs, cb, opaque);
> +    if (!acb) {
> +       return NULL;
> +    }
> +
> +    acb->iscsilun = iscsilun;
> +    acb->qiov     = qiov;
> +
> +    acb->canceled   = 0;
> +
> +    /* XXX we should pass the iovec to write10 to avoid the extra copy */
> +    /* this will allow us to get rid of 'buf' completely */
> +    size = nb_sectors * BDRV_SECTOR_SIZE;
> +    buf = qemu_malloc(size);
> +    qemu_iovec_to_buffer(acb->qiov, buf);
> +    if (iscsi_write10_async(iscsi, iscsilun->lun, buf, size,
> +                           sector_num * BDRV_SECTOR_SIZE
> +                           / iscsilun->block_size,
> +                           0, 0, iscsilun->block_size,
> +                           iscsi_aio_write10_cb, acb) != 0) {

When the function call is this long, perhaps it would be more readable
to assign a temporary variable with the result and use that in if
expression.

The expression sector_num * BDRV_SECTOR_SIZE / iscsilun->block_size is
used often, refactoring this to a function could make the code a bit
clearer.

> +       error_report("iSCSI: Failed to send write10 command. %s",
> +                    iscsi_get_error(iscsi));
> +       qemu_free(buf);
> +       qemu_aio_release(acb);
> +       return NULL;
> +    }
> +    qemu_free(buf);
> +    iscsi_set_events(iscsilun);
> +
> +    return &acb->common;
> +}
> +
> +static void
> +iscsi_aio_read10_cb(struct iscsi_context *iscsi, int status,
> +                   void *command_data, void *private_data)
> +{
> +    ISCSIAIOCB *acb = private_data;
> +    struct scsi_task *scsi = command_data;
> +
> +    if (acb->canceled != 0) {
> +       qemu_aio_release(acb);
> +       return;
> +    }
> +
> +    acb->status = 0;
> +    if (status < 0) {
> +       error_report("Failed to read10 data from iSCSI lun. %s",
> +                    iscsi_get_error(iscsi));
> +       acb->status = -EIO;
> +    } else {
> +       qemu_iovec_from_buffer(acb->qiov, scsi->datain.data, acb->read_size);
> +    }
> +
> +    iscsi_schedule_bh(iscsi_readv_writev_bh_cb, acb);
> +}
> +
> +static BlockDriverAIOCB *
> +iscsi_aio_readv(BlockDriverState *bs, int64_t sector_num,
> +               QEMUIOVector *qiov, int nb_sectors,
> +               BlockDriverCompletionFunc *cb,
> +               void *opaque)
> +{
> +    ISCSILUN *iscsilun = bs->opaque;
> +    struct iscsi_context *iscsi = iscsilun->iscsi;
> +    ISCSIAIOCB *acb;
> +    size_t qemu_read_size, lun_read_size;
> +
> +    qemu_read_size = BDRV_SECTOR_SIZE * (size_t)nb_sectors;
> +    lun_read_size  = (qemu_read_size + iscsilun->block_size - 1)
> +      / iscsilun->block_size * iscsilun->block_size;
> +
> +    acb = qemu_aio_get(&iscsi_aio_pool, bs, cb, opaque);
> +    if (!acb) {
> +       return NULL;
> +    }
> +
> +    acb->iscsilun = iscsilun;
> +    acb->qiov     = qiov;
> +
> +    acb->canceled   = 0;
> +    acb->read_size  = qemu_read_size;
> +
> +    if (iscsi_read10_async(iscsi, iscsilun->lun,
> +                          sector_num * BDRV_SECTOR_SIZE
> +                          / iscsilun->block_size,
> +                          lun_read_size, iscsilun->block_size,
> +                          iscsi_aio_read10_cb, acb) != 0) {
> +       error_report("iSCSI: Failed to send read10 command. %s",
> +                    iscsi_get_error(iscsi));
> +       qemu_aio_release(acb);
> +       return NULL;
> +    }
> +    iscsi_set_events(iscsilun);
> +
> +    return &acb->common;
> +}
> +
> +
> +static void synccache10_cb(struct iscsi_context *iscsi, int status,
> +                          void *command_data, void *private_data)

Usually 'opaque' is used instead of 'private_data'.

> +{
> +    struct iscsi_task *task = private_data;
> +
> +    task->status   = status;
> +    task->complete = 1;
> +}
> +
> +static int
> +iscsi_flush(BlockDriverState *bs)
> +{
> +    ISCSILUN *iscsilun = bs->opaque;
> +    struct iscsi_context *iscsi = iscsilun->iscsi;
> +    struct iscsi_task task;
> +
> +    task.iscsilun = iscsilun;
> +    task.status = 0;
> +    task.complete = 0;
> +
> +    if (iscsi_synchronizecache10_async(iscsi, iscsilun->lun,
> +                                      0, 0, 0, 0,
> +                                      synccache10_cb,
> +                                      &task) != 0) {
> +       error_report("iSCSI: Failed to send SYNCHRONIZECACHE10. %s",
> +                    iscsi_get_error(iscsi));
> +        return -1;
> +    }
> +
> +    async_context_push();
> +    while (!task.complete) {
> +       iscsi_set_events(iscsilun);
> +       qemu_aio_wait();
> +    }
> +    async_context_pop();
> +    if (task.status != 0) {
> +       error_report("iSCSI: Failed to send SYNCHRONIZECACHE10: %s",
> +                    iscsi_get_error(iscsi));
> +       return -EIO;
> +    }
> +
> +    return 0;
> +}
> +
> +static int64_t
> +iscsi_getlength(BlockDriverState *bs)
> +{
> +    ISCSILUN *iscsilun = bs->opaque;
> +    int64_t len;
> +
> +    len  = iscsilun->num_blocks;
> +    len *= iscsilun->block_size;
> +
> +    return len;
> +}
> +
> +static void
> +iscsi_readcapacity10_cb(struct iscsi_context *iscsi, int status,
> +                       void *command_data, void *private_data)
> +{
> +    struct iscsi_task *task = private_data;
> +    struct scsi_readcapacity10 *rc10;
> +    struct scsi_task *scsi = command_data;
> +
> +    if (status != 0) {
> +       error_report("iSCSI: Failed to read capacity of iSCSI lun. %s",
> +                    iscsi_get_error(iscsi));
> +       task->status   = 1;
> +       task->complete = 1;
> +       return;
> +    }
> +
> +    rc10 = scsi_datain_unmarshall(scsi);
> +    if (rc10 == NULL) {
> +       error_report("iSCSI: Failed to unmarshall readcapacity10 data.");
> +       task->status   = 1;
> +       task->complete = 1;
> +       return;
> +    }
> +
> +    task->iscsilun->block_size = rc10->block_size;
> +    task->iscsilun->num_blocks = rc10->lba;
> +
> +    task->status   = 0;
> +    task->complete = 1;
> +}
> +
> +
> +static void
> +iscsi_connect_cb(struct iscsi_context *iscsi, int status, void *command_data,
> +                void *private_data)
> +{
> +    struct iscsi_task *task = private_data;
> +
> +    if (status != 0) {
> +       task->status   = 1;
> +       task->complete = 1;
> +       return;
> +    }
> +
> +    if (iscsi_readcapacity10_async(iscsi, task->iscsilun->lun, 0, 0,
> +                                  iscsi_readcapacity10_cb, private_data)
> +       != 0) {
> +       error_report("iSCSI: failed to send readcapacity command.");
> +       task->status   = 1;
> +       task->complete = 1;
> +    }
> +}
> +
> +/*
> + * We support iscsi url's on the form
> + * iscsi://<host>[:<port>]/<targetname>/<lun>
> + */
> +static int iscsi_open(BlockDriverState *bs, const char *filename, int flags)
> +{
> +    ISCSILUN *iscsilun = bs->opaque;
> +    struct iscsi_context *iscsi = NULL;
> +    struct iscsi_task task;
> +    char *ptr, *host, *target, *url;
> +    char *tmp;
> +    int ret, lun;
> +
> +    bzero(iscsilun, sizeof(ISCSILUN));

memset()

> +
> +    url = qemu_strdup(filename);
> +
> +    if (strncmp(url, "iscsi://", 8)) {
> +       error_report("iSCSI: url does not start with 'iscsi://'");
> +       ret = -EINVAL;
> +       goto failed;
> +    }
> +
> +    host = url + 8;
> +
> +    ptr = index(host, '/');

strchr()