[Qemu-devel] [PATCH 13/14] ./block/iscsi.c

[ronniesahlberg]

From: Ronnie Sahlberg <address@hidden>

This file provides a new protocol ISCSI to qemu and allows qemu
connect directly to iscsi resources, without having to go through
the host scsi layer.
This allows qemu/kvm to use iscsi devices without exposing these
to the host system and without polluting the page cache of the host.

This file provides the bindings between QEMU./KVM and the iscsi library
allowing QEMY to interface to network devices directly.
This library is fully async for read/write and nonblocking and should provide
good performance.
Optimizations are still possible for future enhancements to for example
reduce the number of data copes that are performed in the read/write paths.

Syntax for using iscsi devices is
  iscsi://<host>[:<port>]/<target-iqn-name>/<lun>

Example :
   ... -drive file=iscsi://127.0.0.1:3260/iqn.ronnie.test/1

   ... -cdrom iscsi://127.0.0.1:3260/iqn.ronnie.test/2

This has been tested extensively with TGTS and seems to work well with TGTD
exported devices.
For more general purpose use, support for target initiated NOP exchanges
and CHAP authentication is desired.

Signed-off-by: Ronnie Sahlberg <address@hidden>
---
 block/iscsi.c |  500 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 500 insertions(+), 0 deletions(-)
 create mode 100644 block/iscsi.c

diff --git a/block/iscsi.c b/block/iscsi.c
new file mode 100644
index 0000000..20fc288
--- /dev/null
+++ b/block/iscsi.c
@@ -0,0 +1,500 @@
+/*
+ * 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 <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;
+};
+
+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)
+                           ?iscsi_process_write:NULL,
+                           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;
+
+    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) {
+       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 int
+iscsi_flush(BlockDriverState *bs)
+{
+    ISCSILUN *iscsilun = bs->opaque;
+    struct iscsi_context *iscsi = iscsilun->iscsi;
+    struct scsi_task *task;
+
+    task = iscsi_synchronizecache10_sync(iscsi, iscsilun->lun, 0, 0, 0, 0);
+    if (task == NULL) {
+       error_report("iSCSI: Failed to flush() device.");
+       return -1;
+    }
+    if (task->status != 0) {
+       error_report("iSCSI: Failed to flush to LUN : %s",
+                    iscsi_get_error(iscsi));
+       scsi_free_scsi_task(task);
+       return -1;
+    }
+    scsi_free_scsi_task(task);
+    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));
+
+    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, '/');
+    if (ptr == NULL) {
+       error_report("iSCSI: host is not '/' terminated.");
+       ret = -EINVAL;
+       goto failed;
+    }
+
+    *ptr++ = 0;
+    target = ptr;
+
+    ptr = index(target, '/');
+    if (ptr == NULL) {
+       error_report("iSCSI: host/target is not '/' terminated.");
+       ret = -EINVAL;
+       goto failed;
+    }
+
+    *ptr++ = 0;
+
+    lun = strtol(ptr, &tmp, 10);
+    if (*tmp) {
+       error_report("iSCSI: Invalid LUN specified.");
+       ret = -EINVAL;
+       goto failed;
+    }
+
+    /* Should really append the KVM name after the ':' here */
+    iscsi = iscsi_create_context("iqn.2008-11.org.linux-kvm:");
+    if (iscsi == NULL) {
+       error_report("iSCSI: Failed to create iSCSI context.");
+       ret = -ENOMEM;
+       goto failed;
+    }
+
+    if (iscsi_set_targetname(iscsi, target)) {
+       error_report("iSCSI: Failed to set target name.");
+       ret = -ENOMEM;
+       goto failed;
+    }
+
+    if (iscsi_set_session_type(iscsi, ISCSI_SESSION_NORMAL) != 0) {
+       error_report("iSCSI: Failed to set session type to normal.");
+       ret = -ENOMEM;
+       goto failed;
+    }
+
+    iscsi_set_header_digest(iscsi, ISCSI_HEADER_DIGEST_NONE_CRC32C);
+
+    task.iscsilun = iscsilun;
+    task.status = 0;
+    task.complete = 0;
+
+    iscsilun->iscsi = iscsi;
+    iscsilun->lun   = lun;
+
+    if (iscsi_full_connect_async(iscsi, host, lun, iscsi_connect_cb, &task)
+       != 0) {
+       error_report("iSCSI: Failed to start async connect.");
+       ret = -ENOMEM;
+       goto failed;
+    }
+    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 connect to LUN : %s",
+                    iscsi_get_error(iscsi));
+       ret = -EINVAL;
+       goto failed;
+    }
+
+    return 0;
+
+failed:
+    qemu_free(url);
+    if (iscsi != NULL) {
+       iscsi_destroy_context(iscsi);
+    }
+    bzero(iscsilun, sizeof(ISCSILUN));
+    return ret;
+}
+
+static void iscsi_close(BlockDriverState *bs)
+{
+    ISCSILUN *iscsilun = bs->opaque;
+    struct iscsi_context *iscsi = iscsilun->iscsi;
+
+    qemu_aio_set_fd_handler(iscsi_get_fd(iscsi), NULL, NULL, NULL, NULL, NULL);
+    iscsi_destroy_context(iscsi);
+    bzero(iscsilun, sizeof(ISCSILUN));
+}
+
+static BlockDriver bdrv_iscsi = {
+    .format_name     = "iscsi",
+    .protocol_name   = "iscsi",
+
+    .instance_size   = sizeof(ISCSILUN),
+    .bdrv_file_open  = iscsi_open,
+    .bdrv_close      = iscsi_close,
+    .bdrv_flush      = iscsi_flush,
+
+    .bdrv_getlength  = iscsi_getlength,
+
+    .bdrv_aio_readv  = iscsi_aio_readv,
+    .bdrv_aio_writev = iscsi_aio_writev,
+
+    .bdrv_is_inserted = iscsi_is_inserted,
+};
+
+static void iscsi_block_init(void)
+{
+    bdrv_register(&bdrv_iscsi);
+}
+
+block_init(iscsi_block_init);
-- 
1.7.3.1