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[Qemu-devel] [RFC PATCH v3 3/3] block: add sheepdog driver for distribut


From: MORITA Kazutaka
Subject: [Qemu-devel] [RFC PATCH v3 3/3] block: add sheepdog driver for distributed storage support
Date: Mon, 17 May 2010 19:19:49 +0900

Sheepdog is a distributed storage system for QEMU. It provides highly
available block level storage volumes to VMs like Amazon EBS.  This
patch adds a qemu block driver for Sheepdog.

Sheepdog features are:
- No node in the cluster is special (no metadata node, no control
  node, etc)
- Linear scalability in performance and capacity
- No single point of failure
- Autonomous management (zero configuration)
- Useful volume management support such as snapshot and cloning
- Thin provisioning
- Autonomous load balancing

The more details are available at the project site:
    http://www.osrg.net/sheepdog/

Signed-off-by: MORITA Kazutaka <address@hidden>
---
 Makefile.objs    |    2 +-
 block/sheepdog.c | 1845 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 1846 insertions(+), 1 deletions(-)
 create mode 100644 block/sheepdog.c

diff --git a/Makefile.objs b/Makefile.objs
index ecdd53e..6edbc57 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -14,7 +14,7 @@ block-obj-$(CONFIG_LINUX_AIO) += linux-aio.o
 
 block-nested-y += raw.o cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o bochs.o vpc.o 
vvfat.o
 block-nested-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o
-block-nested-y += parallels.o nbd.o blkdebug.o
+block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o
 block-nested-$(CONFIG_WIN32) += raw-win32.o
 block-nested-$(CONFIG_POSIX) += raw-posix.o
 block-nested-$(CONFIG_CURL) += curl.o
diff --git a/block/sheepdog.c b/block/sheepdog.c
new file mode 100644
index 0000000..4672f00
--- /dev/null
+++ b/block/sheepdog.c
@@ -0,0 +1,1845 @@
+/*
+ * Copyright (C) 2009-2010 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <netdb.h>
+#include <netinet/tcp.h>
+
+#include "qemu-common.h"
+#include "qemu-error.h"
+#include "block_int.h"
+
+#define SD_PROTO_VER 0x01
+
+#define SD_DEFAULT_ADDR "localhost:7000"
+
+#define SD_OP_CREATE_AND_WRITE_OBJ  0x01
+#define SD_OP_READ_OBJ       0x02
+#define SD_OP_WRITE_OBJ      0x03
+
+#define SD_OP_NEW_VDI        0x11
+#define SD_OP_LOCK_VDI       0x12
+#define SD_OP_RELEASE_VDI    0x13
+#define SD_OP_GET_VDI_INFO   0x14
+#define SD_OP_READ_VDIS      0x15
+
+#define SD_FLAG_CMD_WRITE    0x01
+#define SD_FLAG_CMD_COW      0x02
+
+#define SD_RES_SUCCESS       0x00 /* Success */
+#define SD_RES_UNKNOWN       0x01 /* Unknown error */
+#define SD_RES_NO_OBJ        0x02 /* No object found */
+#define SD_RES_EIO           0x03 /* I/O error */
+#define SD_RES_VDI_EXIST     0x04 /* Vdi exists already */
+#define SD_RES_INVALID_PARMS 0x05 /* Invalid parameters */
+#define SD_RES_SYSTEM_ERROR  0x06 /* System error */
+#define SD_RES_VDI_LOCKED    0x07 /* Vdi is locked */
+#define SD_RES_NO_VDI        0x08 /* No vdi found */
+#define SD_RES_NO_BASE_VDI   0x09 /* No base vdi found */
+#define SD_RES_VDI_READ      0x0A /* Cannot read requested vdi */
+#define SD_RES_VDI_WRITE     0x0B /* Cannot write requested vdi */
+#define SD_RES_BASE_VDI_READ 0x0C /* Cannot read base vdi */
+#define SD_RES_BASE_VDI_WRITE   0x0D /* Cannot write base vdi */
+#define SD_RES_NO_TAG        0x0E /* Requested tag is not found */
+#define SD_RES_STARTUP       0x0F /* Sheepdog is on starting up */
+#define SD_RES_VDI_NOT_LOCKED   0x10 /* Vdi is not locked */
+#define SD_RES_SHUTDOWN      0x11 /* Sheepdog is shutting down */
+#define SD_RES_NO_MEM        0x12 /* Cannot allocate memory */
+#define SD_RES_FULL_VDI      0x13 /* we already have the maximum vdis */
+#define SD_RES_VER_MISMATCH  0x14 /* Protocol version mismatch */
+#define SD_RES_NO_SPACE      0x15 /* Server has no room for new objects */
+#define SD_RES_WAIT_FOR_FORMAT  0x16 /* Sheepdog is waiting for a format 
operation */
+#define SD_RES_WAIT_FOR_JOIN    0x17 /* Sheepdog is waiting for other nodes 
joining */
+#define SD_RES_JOIN_FAILED   0x18 /* Target node had failed to join sheepdog */
+
+/*
+ * Object ID rules
+ *
+ *  0 - 19 (20 bits): data object space
+ * 20 - 31 (12 bits): reserved data object space
+ * 32 - 55 (24 bits): vdi object space
+ * 56 - 59 ( 4 bits): reserved vdi object space
+ * 60 - 63 ( 4 bits): object type indentifier space
+ */
+
+#define VDI_SPACE_SHIFT   32
+#define VDI_BIT (UINT64_C(1) << 63)
+#define VMSTATE_BIT (UINT64_C(1) << 62)
+#define MAX_DATA_OBJS (1ULL << 20)
+#define MAX_CHILDREN 1024
+#define SD_MAX_VDI_LEN 256
+#define SD_NR_VDIS   (1U << 24)
+#define SD_DATA_OBJ_SIZE (UINT64_C(1) << 22)
+
+#define SD_INODE_SIZE (sizeof(SheepdogInode))
+#define CURRENT_VDI_ID 0
+
+typedef struct SheepdogReq {
+       uint8_t         proto_ver;
+       uint8_t         opcode;
+       uint16_t        flags;
+       uint32_t        epoch;
+       uint32_t        id;
+       uint32_t        data_length;
+       uint32_t        opcode_specific[8];
+} SheepdogReq;
+
+typedef struct SheepdogRsp {
+       uint8_t         proto_ver;
+       uint8_t         opcode;
+       uint16_t        flags;
+       uint32_t        epoch;
+       uint32_t        id;
+       uint32_t        data_length;
+       uint32_t        result;
+       uint32_t        opcode_specific[7];
+} SheepdogRsp;
+
+typedef struct SheepdogObjReq {
+       uint8_t         proto_ver;
+       uint8_t         opcode;
+       uint16_t        flags;
+       uint32_t        epoch;
+       uint32_t        id;
+       uint32_t        data_length;
+       uint64_t        oid;
+       uint64_t        cow_oid;
+       uint32_t        copies;
+       uint32_t        rsvd;
+       uint64_t        offset;
+} SheepdogObjReq;
+
+typedef struct SheepdogObjRsp {
+       uint8_t         proto_ver;
+       uint8_t         opcode;
+       uint16_t        flags;
+       uint32_t        epoch;
+       uint32_t        id;
+       uint32_t        data_length;
+       uint32_t        result;
+       uint32_t        copies;
+       uint32_t        pad[6];
+} SheepdogObjRsp;
+
+typedef struct SheepdogVdiReq {
+       uint8_t         proto_ver;
+       uint8_t         opcode;
+       uint16_t        flags;
+       uint32_t        epoch;
+       uint32_t        id;
+       uint32_t        data_length;
+       uint64_t        vdi_size;
+       uint32_t        base_vdi_id;
+       uint32_t        copies;
+       uint32_t        snapid;
+       uint32_t        pad[3];
+} SheepdogVdiReq;
+
+typedef struct SheepdogVdiRsp {
+       uint8_t         proto_ver;
+       uint8_t         opcode;
+       uint16_t        flags;
+       uint32_t        epoch;
+       uint32_t        id;
+       uint32_t        data_length;
+       uint32_t        result;
+       uint32_t        rsvd;
+       uint32_t        vdi_id;
+       uint32_t        pad[5];
+} SheepdogVdiRsp;
+
+typedef struct SheepdogInode {
+       char name[SD_MAX_VDI_LEN];
+       uint64_t ctime;
+       uint64_t snap_ctime;
+       uint64_t vm_clock_nsec;
+       uint64_t vdi_size;
+       uint64_t vm_state_size;
+       uint16_t copy_policy;
+       uint8_t  nr_copies;
+       uint8_t  block_size_shift;
+       uint32_t snap_id;
+       uint32_t vdi_id;
+       uint32_t parent_vdi_id;
+       uint32_t child_vdi_id[MAX_CHILDREN];
+       uint32_t data_vdi_id[MAX_DATA_OBJS];
+} SheepdogInode;
+
+/*
+ * 64 bit FNV-1a non-zero initial basis
+ */
+#define FNV1A_64_INIT ((uint64_t)0xcbf29ce484222325ULL)
+
+/*
+ * 64 bit Fowler/Noll/Vo FNV-1a hash code
+ */
+static inline uint64_t fnv_64a_buf(void *buf, size_t len, uint64_t hval)
+{
+        unsigned char *bp = (unsigned char *) buf;
+        unsigned char *be = bp + len;
+        while (bp < be) {
+                hval ^= (uint64_t) *bp++;
+                hval += (hval << 1) + (hval << 4) + (hval << 5) +
+                        (hval << 7) + (hval << 8) + (hval << 40);
+        }
+        return hval;
+}
+
+static inline int is_data_obj_writeable(SheepdogInode *inode, unsigned int idx)
+{
+       return inode->vdi_id == inode->data_vdi_id[idx];
+}
+
+static inline int is_data_obj(uint64_t oid)
+{
+       return !(VDI_BIT & oid);
+}
+
+static inline uint64_t data_oid_to_idx(uint64_t oid)
+{
+       return oid & (MAX_DATA_OBJS - 1);
+}
+
+static inline uint64_t vid_to_vdi_oid(uint32_t vid)
+{
+       return VDI_BIT | ((uint64_t)vid << VDI_SPACE_SHIFT);
+}
+
+static inline uint64_t vid_to_vmstate_oid(uint32_t vid, uint32_t idx)
+{
+       return VMSTATE_BIT | ((uint64_t)vid << VDI_SPACE_SHIFT) | idx;
+}
+
+static inline uint64_t vid_to_data_oid(uint32_t vid, uint32_t idx)
+{
+       return ((uint64_t)vid << VDI_SPACE_SHIFT) | idx;
+}
+
+#undef dprintf
+#ifdef DEBUG_SDOG
+#define dprintf(fmt, args...)                                          \
+do {                                                                   \
+       fprintf(stdout, "%s %d: " fmt, __func__, __LINE__, ##args);     \
+} while (0)
+#else
+#define dprintf(fmt, args...)
+#endif
+
+#define min_t(type, x, y) ({                   \
+       type __min1 = (x);                      \
+       type __min2 = (y);                      \
+       __min1 < __min2 ? __min1: __min2; })
+
+#define max_t(type, x, y) ({                   \
+       type __max1 = (x);                      \
+       type __max2 = (y);                      \
+       __max1 > __max2 ? __max1: __max2; })
+
+typedef struct SheepdogAIOCB SheepdogAIOCB;
+
+typedef struct AIOReq {
+       SheepdogAIOCB *aiocb;
+       unsigned int iov_offset;
+
+       uint64_t oid;
+       uint64_t base_oid;
+       uint64_t offset;
+       unsigned int data_len;
+       uint8_t flags;
+       uint32_t id;
+
+       QLIST_ENTRY(AIOReq) outstanding_aio_siblings;
+       QLIST_ENTRY(AIOReq) aioreq_siblings;
+} AIOReq;
+
+enum AIOCBState {
+       AIOCB_WRITE_UDATA,
+       AIOCB_READ_UDATA,
+};
+
+struct SheepdogAIOCB {
+       BlockDriverAIOCB common;
+
+       QEMUIOVector *qiov;
+
+       int64_t sector_num;
+       int nb_sectors;
+
+       int ret;
+       enum AIOCBState aiocb_type;
+
+       QEMUBH *bh;
+       void (*aio_done_func)(SheepdogAIOCB *);
+
+       int canceled;
+
+       QLIST_HEAD(aioreq_head, AIOReq) aioreq_head;
+};
+
+typedef struct BDRVSheepdogState {
+       SheepdogInode inode;
+
+       uint32_t min_dirty_data_idx;
+       uint32_t max_dirty_data_idx;
+
+       char name[SD_MAX_VDI_LEN];
+       int is_current;
+
+       char *addr;
+       int fd;
+
+       uint32_t aioreq_seq_num;
+       QLIST_HEAD(outstanding_aio_head, AIOReq) outstanding_aio_head;
+} BDRVSheepdogState;
+
+static const char * sd_strerror(int err)
+{
+       int i;
+
+       static const struct {
+               int err;
+               const char *desc;
+       } errors[] = {
+               {SD_RES_SUCCESS, "Success"},
+               {SD_RES_UNKNOWN, "Unknown error"},
+               {SD_RES_NO_OBJ, "No object found"},
+               {SD_RES_EIO, "I/O error"},
+               {SD_RES_VDI_EXIST, "VDI exists already"},
+               {SD_RES_INVALID_PARMS, "Invalid parameters"},
+               {SD_RES_SYSTEM_ERROR, "System error"},
+               {SD_RES_VDI_LOCKED, "VDI is already locked"},
+               {SD_RES_NO_VDI, "No vdi found"},
+               {SD_RES_NO_BASE_VDI, "No base VDI found"},
+               {SD_RES_VDI_READ, "Failed read the requested VDI"},
+               {SD_RES_VDI_WRITE, "Failed to write the requested VDI"},
+               {SD_RES_BASE_VDI_READ, "Failed to read the base VDI"},
+               {SD_RES_BASE_VDI_WRITE, "Failed to write the base VDI"},
+               {SD_RES_NO_TAG, "Failed to find the requested tag"},
+               {SD_RES_STARTUP, "The system is still booting"},
+               {SD_RES_VDI_NOT_LOCKED, "VDI isn't locked"},
+               {SD_RES_SHUTDOWN, "The system is shutting down"},
+               {SD_RES_NO_MEM, "Out of memory on the server"},
+               {SD_RES_FULL_VDI, "We already have the maximum vdis"},
+               {SD_RES_VER_MISMATCH, "Protocol version mismatch"},
+               {SD_RES_NO_SPACE, "Server has no space for new objects"},
+               {SD_RES_WAIT_FOR_FORMAT, "Sheepdog is waiting for a format 
operation"},
+               {SD_RES_WAIT_FOR_JOIN, "Sheepdog is waiting for other nodes 
joining"},
+               {SD_RES_JOIN_FAILED, "Target node had failed to join sheepdog"},
+       };
+
+       for (i = 0; i < ARRAY_SIZE(errors); ++i) {
+               if (errors[i].err == err) {
+                       return errors[i].desc;
+               }
+       }
+
+       return "Invalid error code";
+}
+
+static inline AIOReq *alloc_aio_req(BDRVSheepdogState *s,
+                                   SheepdogAIOCB *acb,
+                                   uint64_t oid, unsigned int data_len,
+                                   uint64_t offset, uint8_t flags,
+                                   uint64_t base_oid,
+                                   unsigned int iov_offset)
+{
+       AIOReq *aio_req;
+
+       aio_req = qemu_malloc(sizeof(*aio_req));
+       aio_req->aiocb = acb;
+       aio_req->iov_offset = iov_offset;
+       aio_req->oid = oid;
+       aio_req->base_oid = base_oid;
+       aio_req->offset = offset;
+       aio_req->data_len = data_len;
+       aio_req->flags = flags;
+       aio_req->id = s->aioreq_seq_num++;
+
+       QLIST_INSERT_HEAD(&s->outstanding_aio_head, aio_req,
+                         outstanding_aio_siblings);
+       QLIST_INSERT_HEAD(&acb->aioreq_head, aio_req, aioreq_siblings);
+
+       return aio_req;
+}
+
+static inline int free_aio_req(BDRVSheepdogState *s, AIOReq *aio_req)
+{
+       SheepdogAIOCB *acb = aio_req->aiocb;
+       QLIST_REMOVE(aio_req, outstanding_aio_siblings);
+       QLIST_REMOVE(aio_req, aioreq_siblings);
+       qemu_free(aio_req);
+
+       return !QLIST_EMPTY(&acb->aioreq_head);
+}
+
+static void sd_finish_aiocb(SheepdogAIOCB *acb)
+{
+       if (!acb->canceled) {
+               acb->common.cb(acb->common.opaque, acb->ret);
+       }
+       qemu_aio_release(acb);
+}
+
+static void sd_aio_cancel(BlockDriverAIOCB *blockacb)
+{
+       SheepdogAIOCB *acb = (SheepdogAIOCB *)blockacb;
+
+       acb->canceled = 1;
+}
+
+static AIOPool sd_aio_pool = {
+       .aiocb_size = sizeof(SheepdogAIOCB),
+       .cancel = sd_aio_cancel,
+};
+
+static SheepdogAIOCB *sd_aio_setup(BlockDriverState *bs, QEMUIOVector *qiov,
+                                  int64_t sector_num, int nb_sectors,
+                                  BlockDriverCompletionFunc *cb,
+                                  void *opaque)
+{
+       SheepdogAIOCB *acb;
+
+       acb = qemu_aio_get(&sd_aio_pool, bs, cb, opaque);
+
+       acb->qiov = qiov;
+
+       acb->sector_num = sector_num;
+       acb->nb_sectors = nb_sectors;
+
+       acb->aio_done_func = NULL;
+       acb->canceled = 0;
+       acb->bh = NULL;
+       acb->ret = 0;
+       QLIST_INIT(&acb->aioreq_head);
+       return acb;
+}
+
+static int sd_schedule_bh(QEMUBHFunc *cb, SheepdogAIOCB *acb)
+{
+       if (acb->bh) {
+               error_report("bug: %d %d\n", acb->aiocb_type, acb->aiocb_type);
+               return -EIO;
+       }
+
+       acb->bh = qemu_bh_new(cb, acb);
+       if (!acb->bh) {
+               error_report("oom: %d %d\n", acb->aiocb_type, acb->aiocb_type);
+               return -EIO;
+       }
+
+       qemu_bh_schedule(acb->bh);
+
+       return 0;
+}
+
+static int do_send_recv(int sockfd, struct iovec *iov, int len, int offset,
+                       int write)
+{
+       struct msghdr msg;
+       int ret, diff;
+
+       memset(&msg, 0, sizeof(msg));
+       msg.msg_iov = iov;
+       msg.msg_iovlen = 1;
+
+       len += offset;
+
+       while (iov->iov_len < len) {
+               len -= iov->iov_len;
+
+               iov++;
+               msg.msg_iovlen++;
+       }
+
+       diff = iov->iov_len - len;
+       iov->iov_len -= diff;
+
+       while (msg.msg_iov->iov_len <= offset) {
+               offset -= msg.msg_iov->iov_len;
+
+               msg.msg_iov++;
+               msg.msg_iovlen--;
+       }
+
+       msg.msg_iov->iov_base = (char *) msg.msg_iov->iov_base + offset;
+       msg.msg_iov->iov_len -= offset;
+
+       if (write) {
+               ret = sendmsg(sockfd, &msg, 0);
+       } else {
+               ret = recvmsg(sockfd, &msg, MSG_WAITALL);
+       }
+
+       msg.msg_iov->iov_base = (char *) msg.msg_iov->iov_base - offset;
+       msg.msg_iov->iov_len += offset;
+
+       iov->iov_len += diff;
+       return ret;
+}
+
+static int connect_to_sdog(const char *addr)
+{
+       char buf[64];
+       char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
+       char name[256], *p;
+       int fd, ret;
+       struct addrinfo hints, *res, *res0;
+       int port = 0;
+
+       if (!addr) {
+               addr = SD_DEFAULT_ADDR;
+       }
+
+       strcpy(name, addr);
+
+       p = name;
+       while (*p) {
+               if (*p == ':') {
+                       *p++ = '\0';
+                       break;
+               } else {
+                       p++;
+               }
+       }
+
+       if (*p == '\0') {
+               error_report("cannot find a port number, %s\n", name);
+               return -1;
+       }
+       port = strtol(p, NULL, 10);
+       if (port == 0) {
+               error_report("invalid port number, %s\n", p);
+               return -1;
+       }
+
+       memset(&hints, 0, sizeof(hints));
+       snprintf(buf, sizeof(buf), "%d", port);
+
+       hints.ai_socktype = SOCK_STREAM;
+
+       ret = getaddrinfo(name, buf, &hints, &res0);
+       if (ret) {
+               error_report("unable to get address info %s, %m\n", name);
+               return -1;
+       }
+
+       for (res = res0; res; res = res->ai_next) {
+               ret = getnameinfo(res->ai_addr, res->ai_addrlen,
+                                 hbuf, sizeof(hbuf), sbuf, sizeof(sbuf),
+                                 NI_NUMERICHOST | NI_NUMERICSERV);
+               if (ret) {
+                       continue;
+               }
+
+               fd = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
+               if (fd < 0) {
+                       continue;
+               }
+
+reconnect:
+               ret = connect(fd, res->ai_addr, res->ai_addrlen);
+               if (ret < 0) {
+                       if (errno == EINTR) {
+                               goto reconnect;
+                       }
+                       break;
+               }
+
+               dprintf("connected to %s:%d\n", name, port);
+               goto success;
+       }
+       fd = -1;
+       error_report("failed connect to %s:%d\n", name, port);
+success:
+       freeaddrinfo(res0);
+       return fd;
+}
+
+static int do_readv_writev(int sockfd, struct iovec *iov, int len,
+                          int iov_offset, int write)
+{
+       int ret;
+again:
+       ret = do_send_recv(sockfd, iov, len, iov_offset, write);
+       if (ret < 0) {
+               if (errno == EINTR || errno == EAGAIN) {
+                       goto again;
+               }
+               error_report("failed to recv a rsp, %m\n");
+               return 1;
+       }
+
+       iov_offset += ret;
+       len -= ret;
+       if (len) {
+               goto again;
+       }
+
+       return 0;
+}
+
+static int do_readv(int sockfd, struct iovec *iov, int len, int iov_offset)
+{
+       return do_readv_writev(sockfd, iov, len, iov_offset, 0);
+}
+
+static int do_writev(int sockfd, struct iovec *iov, int len, int iov_offset)
+{
+       return do_readv_writev(sockfd, iov, len, iov_offset, 1);
+}
+
+static int do_read_write(int sockfd, void *buf, int len, int write)
+{
+       struct iovec iov;
+
+       iov.iov_base = buf;
+       iov.iov_len = len;
+
+       return do_readv_writev(sockfd, &iov, len, 0, write);
+}
+
+static int do_read(int sockfd, void *buf, int len)
+{
+       return do_read_write(sockfd, buf, len, 0);
+}
+
+static int do_write(int sockfd, void *buf, int len)
+{
+       return do_read_write(sockfd, buf, len, 1);
+}
+
+static int send_req(int sockfd, SheepdogReq *hdr, void *data,
+                   unsigned int *wlen)
+{
+       int ret;
+       struct iovec iov[2];
+
+       iov[0].iov_base = hdr;
+       iov[0].iov_len = sizeof(*hdr);
+
+       if (*wlen) {
+               iov[1].iov_base = data;
+               iov[1].iov_len = *wlen;
+       }
+
+       ret = do_writev(sockfd, iov, sizeof(*hdr) + *wlen, 0);
+       if (ret) {
+               error_report("failed to send a req, %m\n");
+               ret = -1;
+       }
+
+       return ret;
+}
+
+static int do_req(int sockfd, SheepdogReq *hdr, void *data,
+                 unsigned int *wlen, unsigned int *rlen)
+{
+       int ret;
+
+       ret = send_req(sockfd, hdr, data, wlen);
+       if (ret) {
+               ret = -1;
+               goto out;
+       }
+
+       ret = do_read(sockfd, hdr, sizeof(*hdr));
+       if (ret) {
+               error_report("failed to get a rsp, %m\n");
+               ret = -1;
+               goto out;
+       }
+
+       if (*rlen > hdr->data_length) {
+               *rlen = hdr->data_length;
+       }
+
+       if (*rlen) {
+               ret = do_read(sockfd, data, *rlen);
+               if (ret) {
+                       error_report("failed to get the data, %m\n");
+                       ret = -1;
+                       goto out;
+               }
+       }
+       ret = 0;
+out:
+       return ret;
+}
+
+static int add_aio_request(BDRVSheepdogState *s, AIOReq *aio_req,
+                          struct iovec *iov, int niov, int create,
+                          enum AIOCBState aiocb_type);
+
+static void send_pending_req(BDRVSheepdogState *s, uint64_t oid, uint32_t id)
+{
+       AIOReq *aio_req, *next;
+       SheepdogAIOCB *acb;
+       int ret;
+
+       QLIST_FOREACH_SAFE(aio_req, &s->outstanding_aio_head,
+                          outstanding_aio_siblings, next) {
+               if (id == aio_req->id) {
+                       continue;
+               }
+               if (aio_req->oid != oid) {
+                       continue;
+               }
+
+               acb = aio_req->aiocb;
+               ret = add_aio_request(s, aio_req, acb->qiov->iov,
+                                     acb->qiov->niov, 0, acb->aiocb_type);
+               if (ret < 0) {
+                       error_report("add_aio_request is faled\n");
+                       free_aio_req(s, aio_req);
+                       if (QLIST_EMPTY(&acb->aioreq_head)) {
+                               sd_finish_aiocb(acb);
+                       }
+               }
+       }
+}
+
+static void aio_read_response(void *opaque)
+{
+       SheepdogObjReq hdr;
+       SheepdogObjRsp *rsp = (SheepdogObjRsp *)&hdr;
+       BDRVSheepdogState *s = (BDRVSheepdogState *)opaque;
+       int fd = s->fd;
+       int ret;
+       AIOReq *aio_req = NULL;
+       SheepdogAIOCB *acb;
+       int rest;
+       unsigned long idx;
+
+       if (QLIST_EMPTY(&s->outstanding_aio_head)) {
+               return;
+       }
+
+       ret = do_read(fd, (void *)rsp, sizeof(*rsp));
+       if (ret) {
+               error_report("failed to get the header, %m\n");
+               return;
+       }
+
+       QLIST_FOREACH(aio_req, &s->outstanding_aio_head, 
outstanding_aio_siblings) {
+               if (aio_req->id == rsp->id) {
+                       break;
+               }
+       }
+       if (!aio_req) {
+               error_report("cannot find aio_req %x\n", rsp->id);
+               return;
+       }
+
+       acb = aio_req->aiocb;
+
+       switch (acb->aiocb_type) {
+       case AIOCB_WRITE_UDATA:
+               if (!is_data_obj(aio_req->oid)) {
+                       break;
+               }
+               idx = data_oid_to_idx(aio_req->oid);
+
+               if (s->inode.data_vdi_id[idx] != s->inode.vdi_id) {
+                       s->inode.data_vdi_id[idx] = s->inode.vdi_id;
+                       s->max_dirty_data_idx = max_t(uint32_t, idx,
+                                                     s->max_dirty_data_idx);
+                       s->min_dirty_data_idx = min_t(uint32_t, idx,
+                                                     s->min_dirty_data_idx);
+
+                       send_pending_req(s, vid_to_data_oid(s->inode.vdi_id, 
idx),
+                                        rsp->id);
+               }
+               break;
+       case AIOCB_READ_UDATA:
+               ret = do_readv(fd, acb->qiov->iov, rsp->data_length,
+                              aio_req->iov_offset);
+               if (ret) {
+                       error_report("failed to get the data, %m\n");
+                       return;
+               }
+               break;
+       }
+
+       if (rsp->result != SD_RES_SUCCESS) {
+               acb->ret = -EIO;
+               error_report("%s\n", sd_strerror(rsp->result));
+       }
+
+       rest = free_aio_req(s, aio_req);
+       if (!rest) {
+               acb->aio_done_func(acb);
+       }
+}
+
+static int aio_flush_request(void *opaque)
+{
+       BDRVSheepdogState *s = (BDRVSheepdogState *)opaque;
+
+       return !QLIST_EMPTY(&s->outstanding_aio_head);
+}
+
+static int set_nonblocking(int fd)
+{
+       int ret;
+
+       ret = fcntl(fd, F_GETFL);
+       if (ret < 0) {
+               error_report("can't fcntl (F_GETFL), %m\n");
+               close(fd);
+       } else {
+               ret = fcntl(fd, F_SETFL, ret | O_NONBLOCK);
+               if (ret < 0) {
+                       error_report("can't fcntl (O_NONBLOCK), %m\n");
+               }
+       }
+
+       return ret;
+}
+
+static int set_nodelay(int fd)
+{
+       int ret, opt;
+
+       opt = 1;
+       ret = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &opt, sizeof(opt));
+       return ret;
+}
+
+/*
+ * Return a socket discriptor to read/write objects.
+ * We cannot use this discriptor for other operations because
+ * the block driver may be on waiting response from the server.
+ */
+static int get_sheep_fd(BDRVSheepdogState *s)
+{
+       int ret, fd;
+
+       fd = connect_to_sdog(s->addr);
+       if (fd < 0) {
+               error_report("%m\n");
+               return -1;
+       }
+
+       ret = set_nonblocking(fd);
+       if (ret) {
+               error_report("%m\n");
+               close(fd);
+               return -1;
+       }
+
+       ret = set_nodelay(fd);
+       if (ret) {
+               error_report("%m\n");
+               close(fd);
+               return -1;
+       }
+
+       qemu_aio_set_fd_handler(fd, aio_read_response, NULL, aio_flush_request,
+                               NULL, s);
+       s->fd = fd;
+
+       return fd;
+}
+
+static int parse_vdiname(BDRVSheepdogState *s, const char *filename,
+                        char *vdi, int vdi_len, uint32_t *snapid)
+{
+       char *p, *q;
+       int nr_sep;
+
+       p = q = strdup(filename);
+
+       if (!p) {
+               return 1;
+       }
+
+       nr_sep = 0;
+       while (*p) {
+               if (*p == ':') {
+                       nr_sep++;
+               }
+               if (nr_sep == 2) {
+                       break;
+               }
+               p++;
+       }
+
+       if (nr_sep == 2) {
+               *p++ = '\0';
+       } else {
+               p = q;
+       }
+
+       strncpy(vdi, p, vdi_len);
+
+       p = strchr(vdi, ':');
+       if (p) {
+               *p++ = '\0';
+               *snapid = strtol(p, NULL, 10);
+       } else {
+               *snapid = CURRENT_VDI_ID; /* search current vdi */
+       }
+
+       if (nr_sep == 2) {
+               s->addr = q;
+       } else {
+               free(q);
+               s->addr = NULL;
+       }
+
+       return 0;
+}
+
+static int find_vdi_name(BDRVSheepdogState *s, char *filename, uint32_t snapid,
+                        uint32_t *vid, int for_snapshot)
+{
+       int ret, fd;
+       SheepdogVdiReq hdr;
+       SheepdogVdiRsp *rsp = (SheepdogVdiRsp *)&hdr;
+       unsigned int wlen, rlen = 0;
+       char buf[SD_MAX_VDI_LEN];
+
+       fd = connect_to_sdog(s->addr);
+       if (fd < 0) {
+               return -1;
+       }
+
+       memset(&hdr, 0, sizeof(hdr));
+       snprintf(buf, sizeof(buf), "%s", filename);
+       if (for_snapshot) {
+               hdr.opcode = SD_OP_GET_VDI_INFO;
+       } else {
+               hdr.opcode = SD_OP_LOCK_VDI;
+       }
+       wlen = SD_MAX_VDI_LEN;
+       hdr.proto_ver = SD_PROTO_VER;
+       hdr.data_length = SD_MAX_VDI_LEN;
+       hdr.snapid = snapid;
+       hdr.flags = SD_FLAG_CMD_WRITE;
+
+       ret = do_req(fd, (SheepdogReq *)&hdr, buf, &wlen, &rlen);
+       if (ret) {
+               ret = -1;
+               goto out;
+       }
+
+       if (rsp->result != SD_RES_SUCCESS) {
+               error_report("%s, %s\n", sd_strerror(rsp->result), filename);
+               ret = -1;
+               goto out;
+       }
+       *vid = rsp->vdi_id;
+
+       ret = 0;
+out:
+       close(fd);
+       return ret;
+}
+
+static int add_aio_request(BDRVSheepdogState *s, AIOReq *aio_req,
+                          struct iovec *iov, int niov, int create,
+                          enum AIOCBState aiocb_type)
+{
+       int nr_copies = s->inode.nr_copies;
+       SheepdogObjReq hdr;
+       unsigned int wlen;
+       int ret, opt;
+       uint64_t oid = aio_req->oid;
+       unsigned int datalen = aio_req->data_len;
+       uint64_t offset = aio_req->offset;
+       uint8_t flags = aio_req->flags;
+       uint64_t old_oid = aio_req->base_oid;
+
+       if (!nr_copies) {
+               error_report("bug\n");
+       }
+
+       memset(&hdr, 0, sizeof(hdr));
+
+       if (aiocb_type == AIOCB_READ_UDATA) {
+               wlen = 0;
+               hdr.opcode = SD_OP_READ_OBJ;
+               hdr.flags = flags;
+       } else if (create) {
+               wlen = datalen;
+               hdr.opcode = SD_OP_CREATE_AND_WRITE_OBJ;
+               hdr.flags = SD_FLAG_CMD_WRITE | flags;
+       } else {
+               wlen = datalen;
+               hdr.opcode = SD_OP_WRITE_OBJ;
+               hdr.flags = SD_FLAG_CMD_WRITE | flags;
+       }
+
+       hdr.oid = oid;
+       hdr.cow_oid = old_oid;
+       hdr.copies = s->inode.nr_copies;
+
+       hdr.data_length = datalen;
+       hdr.offset = offset;
+
+       hdr.id = aio_req->id;
+
+       opt = 1;
+       setsockopt(s->fd, SOL_TCP, TCP_CORK, &opt, sizeof(opt));
+
+       ret = do_write(s->fd, &hdr, sizeof(hdr));
+       if (ret) {
+               error_report("failed to send a req, %m\n");
+               return -EIO;
+       }
+
+       if (wlen) {
+               ret = do_writev(s->fd, iov, wlen, aio_req->iov_offset);
+               if (ret) {
+                       error_report("failed to send a data, %m\n");
+                       return -EIO;
+               }
+       }
+        opt = 0;
+        setsockopt(s->fd, SOL_TCP, TCP_CORK, &opt, sizeof(opt));
+
+       return 0;
+}
+
+static int read_write_object(int fd, char *buf, uint64_t oid, int copies,
+                            unsigned int datalen, uint64_t offset,
+                            int write, int create)
+{
+       SheepdogObjReq hdr;
+       SheepdogObjRsp *rsp = (SheepdogObjRsp *)&hdr;
+       unsigned int wlen, rlen;
+       int ret;
+
+       memset(&hdr, 0, sizeof(hdr));
+
+       if (write) {
+               wlen = datalen;
+               rlen = 0;
+               hdr.flags = SD_FLAG_CMD_WRITE;
+               if (create) {
+                       hdr.opcode = SD_OP_CREATE_AND_WRITE_OBJ;
+               } else {
+                       hdr.opcode = SD_OP_WRITE_OBJ;
+               }
+       } else {
+               wlen = 0;
+               rlen = datalen;
+               hdr.opcode = SD_OP_READ_OBJ;
+       }
+       hdr.oid = oid;
+       hdr.data_length = datalen;
+       hdr.offset = offset;
+       hdr.copies = copies;
+
+       ret = do_req(fd, (SheepdogReq *)&hdr, buf, &wlen, &rlen);
+       if (ret) {
+               error_report("failed to send a request to the sheep\n");
+               return -1;
+       }
+
+       switch (rsp->result) {
+       case SD_RES_SUCCESS:
+               return 0;
+       default:
+               error_report("%s\n", sd_strerror(rsp->result));
+               return -1;
+       }
+}
+
+static int read_object(int fd, char *buf, uint64_t oid, int copies,
+                      unsigned int datalen, uint64_t offset)
+{
+       return read_write_object(fd, buf, oid, copies, datalen, offset, 0, 0);
+}
+
+static int write_object(int fd, char *buf, uint64_t oid, int copies,
+                       unsigned int datalen, uint64_t offset, int create)
+{
+       return read_write_object(fd, buf, oid, copies, datalen, offset, 1, 
create);
+}
+
+/* TODO: error cleanups */
+static int sd_open(BlockDriverState *bs, const char *filename, int flags)
+{
+       int ret, fd;
+       uint32_t vid = 0;
+       BDRVSheepdogState *s = bs->opaque;
+       char vdi[256];
+       uint32_t snapid;
+       int for_snapshot = 0;
+       char *buf;
+
+       strstart(filename, "sheepdog:", (const char **)&filename);
+
+       buf = qemu_malloc(SD_INODE_SIZE);
+
+       memset(vdi, 0, sizeof(vdi));
+       if (parse_vdiname(s, filename, vdi, sizeof(vdi), &snapid) < 0) {
+               goto out;
+       }
+       s->fd = get_sheep_fd(s);
+       if (s->fd < 0) {
+               return -1;
+       }
+
+       if (snapid != CURRENT_VDI_ID) {
+               for_snapshot = 1;
+       }
+
+       ret = find_vdi_name(s, vdi, snapid, &vid, for_snapshot);
+       if (ret) {
+               goto out;
+       }
+
+       if (snapid) {
+               dprintf("%" PRIx32 " non current inode was open.\n", vid);
+       } else {
+               s->is_current = 1;
+       }
+
+       fd = connect_to_sdog(s->addr);
+       if (fd < 0) {
+               error_report("failed to connect\n");
+               goto out;
+       }
+
+       ret = read_object(fd, buf, vid_to_vdi_oid(vid), 0, SD_INODE_SIZE, 0);
+
+       close(fd);
+
+       if (ret) {
+               goto out;
+       }
+
+       memcpy(&s->inode, buf, sizeof(s->inode));
+       s->min_dirty_data_idx = UINT32_MAX;
+       s->max_dirty_data_idx = 0;
+
+       bs->total_sectors = s->inode.vdi_size >> 9;
+       strncpy(s->name, vdi, sizeof(s->name));
+       qemu_free(buf);
+
+       QLIST_INIT(&s->outstanding_aio_head);
+       return 0;
+out:
+       qemu_free(buf);
+       return -1;
+}
+
+static int do_sd_create(const char *addr, char *filename, char *tag,
+                       int64_t total_sectors, uint32_t base_vid,
+                       uint32_t *vdi_id, int snapshot)
+{
+       SheepdogVdiReq hdr;
+       SheepdogVdiRsp *rsp = (SheepdogVdiRsp *)&hdr;
+       int fd, ret;
+       unsigned int wlen, rlen = 0;
+       char buf[SD_MAX_VDI_LEN];
+
+       fd = connect_to_sdog(addr);
+       if (fd < 0) {
+               return -1;
+       }
+
+       strncpy(buf, filename, SD_MAX_VDI_LEN);
+
+       memset(&hdr, 0, sizeof(hdr));
+       hdr.opcode = SD_OP_NEW_VDI;
+       hdr.base_vdi_id = base_vid;
+
+       wlen = SD_MAX_VDI_LEN;
+
+       hdr.flags = SD_FLAG_CMD_WRITE;
+       hdr.snapid = snapshot;
+
+       hdr.data_length = wlen;
+       hdr.vdi_size = total_sectors * 512;
+
+       ret = do_req(fd, (SheepdogReq *)&hdr, buf, &wlen, &rlen);
+
+       close(fd);
+
+       if (ret) {
+               return -1;
+       }
+
+       if (rsp->result != SD_RES_SUCCESS) {
+               error_report("%s, %s\n", sd_strerror(rsp->result), filename);
+               return -1;
+       }
+
+       if (vdi_id) {
+               *vdi_id = rsp->vdi_id;
+       }
+
+       return 0;
+}
+
+static int sd_create(const char *filename, QEMUOptionParameter *options)
+{
+       int ret;
+       uint32_t vid = 0;
+       int64_t total_sectors = 0;
+       char *backing_file = NULL;
+
+       strstart(filename, "sheepdog:", (const char **)&filename);
+
+       while (options && options->name) {
+               if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
+                       total_sectors = options->value.n / 512;
+               } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) {
+                       backing_file = options->value.s;
+               }
+               options++;
+       }
+
+       if (backing_file) {
+               BlockDriverState bs;
+               char vdi[SD_MAX_VDI_LEN];
+               uint32_t snapid;
+
+               strstart(backing_file, "sheepdog:", (const char 
**)&backing_file);
+               memset(&bs, 0, sizeof(bs));
+
+               bs.opaque = qemu_malloc(sizeof(BDRVSheepdogState));
+
+               ret = sd_open(&bs, backing_file, 0);
+               if (ret < 0) {
+                       return -1;
+               }
+
+               if (parse_vdiname(bs.opaque, backing_file, vdi, sizeof(vdi), 
&snapid) < 0) {
+                       return -1;
+               }
+
+               /* cannot clone from a current inode */
+               if (snapid == CURRENT_VDI_ID) {
+                       return -1;
+               }
+
+               ret = find_vdi_name(bs.opaque, vdi, snapid, &vid, 1);
+               if (ret) {
+                       return -1;
+               }
+       }
+
+       return do_sd_create(NULL, (char *)filename, NULL, total_sectors, vid,
+                           NULL, 0);
+}
+
+static void sd_close(BlockDriverState *bs)
+{
+       BDRVSheepdogState *s = bs->opaque;
+       SheepdogVdiReq hdr;
+       SheepdogVdiRsp *rsp = (SheepdogVdiRsp *)&hdr;
+       unsigned int wlen, rlen = 0;
+       int fd, ret;
+
+       dprintf("%s\n", s->name);
+
+       fd = connect_to_sdog(s->addr);
+       if (fd < 0) {
+               return;
+       }
+
+       memset(&hdr, 0, sizeof(hdr));
+
+       hdr.opcode = SD_OP_RELEASE_VDI;
+       wlen = strlen(s->name) + 1;
+       hdr.data_length = wlen;
+       hdr.flags = SD_FLAG_CMD_WRITE;
+
+       ret = do_req(fd, (SheepdogReq *)&hdr, s->name, &wlen, &rlen);
+
+       close(fd);
+
+       if (!ret && rsp->result != SD_RES_SUCCESS &&
+           rsp->result != SD_RES_VDI_NOT_LOCKED) {
+               error_report("%s, %s\n", sd_strerror(rsp->result), s->name);
+       }
+
+       close(s->fd);
+       free(s->addr);
+}
+
+static void sd_write_done(SheepdogAIOCB *acb)
+{
+       int ret;
+       BDRVSheepdogState *s = acb->common.bs->opaque;
+       struct iovec iov;
+       AIOReq *aio_req;
+       uint32_t offset, data_len, mn, mx;
+
+       mn = s->min_dirty_data_idx;
+       mx = s->max_dirty_data_idx;
+       if (mn <= mx) {
+               offset = sizeof(s->inode) - sizeof(s->inode.data_vdi_id) +
+                       mn * sizeof(s->inode.data_vdi_id[0]);
+               data_len = (mx - mn + 1) * sizeof(s->inode.data_vdi_id[0]);
+
+               s->min_dirty_data_idx = UINT32_MAX;
+               s->max_dirty_data_idx = 0;
+
+               iov.iov_base = &s->inode;
+               iov.iov_len = sizeof(s->inode);
+               aio_req = alloc_aio_req(s, acb, vid_to_vdi_oid(s->inode.vdi_id),
+                                       data_len, offset, 0, 0, offset);
+               if (!aio_req) {
+                       error_report("too many requests\n");
+                       acb->ret = -EIO;
+                       goto out;
+               }
+               ret = add_aio_request(s, aio_req, &iov, 1, 0, 
AIOCB_WRITE_UDATA);
+               if (ret) {
+                       free_aio_req(s, aio_req);
+                       acb->ret = -EIO;
+                       goto out;
+               }
+
+               acb->aio_done_func = sd_finish_aiocb;
+               acb->aiocb_type = AIOCB_WRITE_UDATA;
+               return;
+       }
+out:
+       sd_finish_aiocb(acb);
+}
+
+static int sd_create_branch(BDRVSheepdogState *s)
+{
+       int ret, fd;
+       uint32_t vid;
+       char *buf;
+
+       dprintf("%" PRIx32 " is not current.\n", s->inode.vdi_id);
+
+       buf = qemu_malloc(SD_INODE_SIZE);
+
+       ret = do_sd_create(s->addr, s->name, NULL, s->inode.vdi_size >> 9,
+                          s->inode.vdi_id, &vid, 1);
+       if (ret) {
+               goto out;
+       }
+
+       dprintf("%" PRIx32 " is created.\n", vid);
+
+       fd = connect_to_sdog(s->addr);
+       if (fd < 0) {
+               error_report("failed to connect\n");
+               goto out;
+       }
+
+       ret = read_object(fd, buf, vid_to_vdi_oid(vid), s->inode.nr_copies,
+                         SD_INODE_SIZE, 0);
+
+       close(fd);
+
+       if (ret < 0) {
+               goto out;
+       }
+
+       memcpy(&s->inode, buf, sizeof(s->inode));
+
+       s->is_current = 1;
+       ret = 0;
+       dprintf("%" PRIx32 " was newly created.\n", s->inode.vdi_id);
+
+out:
+       qemu_free(buf);
+
+       return ret;
+}
+
+static void sd_readv_writev_bh_cb(void *p)
+{
+       SheepdogAIOCB *acb = p;
+       int ret = 0;
+       unsigned long len, done = 0, total = acb->nb_sectors * 512;
+       unsigned long idx = acb->sector_num * 512 / SD_DATA_OBJ_SIZE;
+       uint64_t oid;
+       uint64_t offset = (acb->sector_num * 512) % SD_DATA_OBJ_SIZE;
+       BDRVSheepdogState *s = acb->common.bs->opaque;
+       SheepdogInode *inode = &s->inode;
+       AIOReq *aio_req;
+
+       qemu_bh_delete(acb->bh);
+       acb->bh = NULL;
+
+       if (acb->aiocb_type == AIOCB_WRITE_UDATA && !s->is_current) {
+               ret = sd_create_branch(s);
+               if (ret) {
+                       acb->ret = -EIO;
+                       goto out;
+               }
+       }
+
+       while (done != total) {
+               uint8_t flags = 0;
+               uint64_t old_oid = 0;
+               int create = 0;
+
+               oid = vid_to_data_oid(inode->data_vdi_id[idx], idx);
+
+               len = min_t(unsigned long, total - done, SD_DATA_OBJ_SIZE - 
offset);
+
+               if (!inode->data_vdi_id[idx]) {
+                       if (acb->aiocb_type == AIOCB_READ_UDATA) {
+                               goto done;
+                       }
+
+                       create = 1;
+               } else if (acb->aiocb_type == AIOCB_WRITE_UDATA
+                          && !is_data_obj_writeable(inode, idx)) {
+                       create = 1;
+                       old_oid = oid;
+                       flags = SD_FLAG_CMD_COW;
+               }
+
+               if (create) {
+                       dprintf("update ino (%" PRIu32") %"
+                               PRIu64 " %" PRIu64 " %" PRIu64 "\n",
+                               inode->vdi_id, oid,
+                               vid_to_data_oid(inode->data_vdi_id[idx], idx), 
idx);
+                       oid = vid_to_data_oid(inode->vdi_id, idx);
+                       dprintf("new oid %lx\n", oid);
+               }
+
+               aio_req = alloc_aio_req(s, acb, oid, len, offset, flags,
+                                       old_oid, done);
+               if (!aio_req) {
+                       error_report("too many requests\n");
+                       acb->ret = -EIO;
+                       goto out;
+               }
+
+               if (create) {
+                       AIOReq *areq;
+                       QLIST_FOREACH(areq, &s->outstanding_aio_head,
+                                     outstanding_aio_siblings) {
+                               if (areq == aio_req) {
+                                       continue;
+                               }
+                               if (areq->oid == oid) {
+                                       aio_req->flags = 0;
+                                       aio_req->base_oid = 0;
+                                       goto done;
+                               }
+                       }
+               }
+
+               ret = add_aio_request(s, aio_req, acb->qiov->iov, 
acb->qiov->niov,
+                                     create, acb->aiocb_type);
+               if (ret < 0) {
+                       error_report("add_aio_request is faled\n");
+                       free_aio_req(s, aio_req);
+                       acb->ret = -EIO;
+                       goto out;
+               }
+       done:
+               offset = 0;
+               idx++;
+               done += len;
+       }
+out:
+       if (QLIST_EMPTY(&acb->aioreq_head)) {
+               sd_finish_aiocb(acb);
+       }
+}
+
+static BlockDriverAIOCB *sd_aio_writev(BlockDriverState *bs,
+                                      int64_t sector_num,
+                                      QEMUIOVector *qiov,
+                                      int nb_sectors,
+                                      BlockDriverCompletionFunc *cb,
+                                      void *opaque)
+{
+       SheepdogAIOCB *acb;
+
+       acb = sd_aio_setup(bs, qiov, sector_num, nb_sectors, cb, opaque);
+       acb->aio_done_func = sd_write_done;
+       acb->aiocb_type = AIOCB_WRITE_UDATA;
+
+       sd_schedule_bh(sd_readv_writev_bh_cb, acb);
+       return &acb->common;
+}
+
+static BlockDriverAIOCB *sd_aio_readv(BlockDriverState *bs,
+                                     int64_t sector_num,
+                                     QEMUIOVector *qiov,
+                                     int nb_sectors,
+                                     BlockDriverCompletionFunc *cb,
+                                     void *opaque)
+{
+       SheepdogAIOCB *acb;
+       int i;
+
+       acb = sd_aio_setup(bs, qiov, sector_num, nb_sectors, cb, opaque);
+       acb->aiocb_type = AIOCB_READ_UDATA;
+       acb->aio_done_func = sd_finish_aiocb;
+
+       /*
+        * TODO: we can do better; we don't need to initialize
+        * blindly.
+        */
+       for (i = 0; i < qiov->niov; i++) {
+               memset(qiov->iov[i].iov_base, 0, qiov->iov[i].iov_len);
+       }
+
+       sd_schedule_bh(sd_readv_writev_bh_cb, acb);
+       return &acb->common;
+}
+
+static int sd_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
+{
+       BDRVSheepdogState *s = bs->opaque;
+       int ret, fd;
+       uint32_t new_vid;
+       SheepdogInode *inode;
+       unsigned int datalen;
+       uint64_t offset;
+
+       dprintf("sn_info: name %s id_str %s s: name %s vm_state_size %d "
+               "is_current %d\n", sn_info->name, sn_info->id_str,
+               s->name, sn_info->vm_state_size, s->is_current);
+
+       if (!s->is_current) {
+               error_report("You can't create a snapshot of "
+                       "a non current VDI, %s (%" PRIu32 ").\n",
+                       s->name, s->inode.vdi_id);
+
+               return -1;
+       }
+
+       dprintf("%s %s\n", sn_info->name, sn_info->id_str);
+
+       s->inode.vm_state_size = sn_info->vm_state_size;
+       s->inode.vm_clock_nsec = sn_info->vm_clock_nsec;
+       offset = 0;
+       /* we don't need to read entire object */
+       datalen = SD_INODE_SIZE - sizeof(s->inode.data_vdi_id);
+
+       /* refresh inode. */
+       fd = connect_to_sdog(s->addr);
+       if (fd < 0) {
+               ret = -EIO;
+               goto cleanup;
+       }
+
+       ret = write_object(fd, (char *)&s->inode, 
vid_to_vdi_oid(s->inode.vdi_id),
+                          s->inode.nr_copies, datalen, offset, 0);
+       if (ret < 0) {
+               error_report("failed to write snapshot's inode.\n");
+               ret = -EIO;
+               goto cleanup;
+       }
+
+       ret = do_sd_create(s->addr, s->name, NULL, s->inode.vdi_size >> 9,
+                          s->inode.vdi_id, &new_vid, 1);
+       if (ret < 0) {
+               error_report("failed to create inode for snapshot. %m\n");
+               ret = -EIO;
+               goto cleanup;
+       }
+
+       inode = (SheepdogInode *)qemu_malloc(datalen);
+
+       ret = read_object(fd, (char *)inode, vid_to_vdi_oid(new_vid),
+                         s->inode.nr_copies, datalen, offset);
+
+       close(fd);
+
+       if (ret < 0) {
+               error_report("failed to read new inode info. %m\n");
+               ret = -EIO;
+               goto cleanup;
+       }
+
+       memcpy(&s->inode, inode, datalen);
+       dprintf("s->inode: name %s snap_id %x oid %x\n",
+               s->inode.name, s->inode.snap_id, s->inode.vdi_id);
+
+cleanup:
+       close(fd);
+       return ret;
+}
+
+static int sd_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
+{
+       BDRVSheepdogState *s = bs->opaque;
+       BDRVSheepdogState *old_s;
+       char vdi[SD_MAX_VDI_LEN];
+       char *buf = NULL;
+       uint32_t vid;
+       uint32_t snapid = 0;
+       int ret = -ENOENT, fd;
+
+       old_s = qemu_malloc(sizeof(BDRVSheepdogState));
+
+       memcpy(old_s, s, sizeof(BDRVSheepdogState));
+
+       snapid = strtol(snapshot_id, NULL, 10);
+       if (!snapid) {
+               error_report("Invalid snapshot_id\n");
+               goto out;
+       }
+
+       buf = qemu_malloc(SD_INODE_SIZE);
+       strncpy(vdi, s->name, sizeof(vdi));
+       ret = find_vdi_name(s, vdi, snapid, &vid, 1);
+       if (ret) {
+               error_report("Failed to find_vdi_name\n");
+               ret = -ENOENT;
+               goto out;
+       }
+
+       fd = connect_to_sdog(s->addr);
+       if (fd < 0) {
+               error_report("failed to connect\n");
+               goto out;
+       }
+
+       ret = read_object(fd, buf, vid_to_vdi_oid(vid), s->inode.nr_copies,
+                         SD_INODE_SIZE, 0);
+
+       close(fd);
+
+       if (ret) {
+               ret = -ENOENT;
+               goto out;
+       }
+
+       memcpy(&s->inode, buf, sizeof(s->inode));
+
+       if (!s->inode.vm_state_size) {
+               error_report("Invalid snapshot\n");
+               ret = -ENOENT;
+               goto out;
+       }
+
+       s->is_current = 0;
+
+       qemu_free(buf);
+       qemu_free(old_s);
+
+       return 0;
+out:
+       /* recover bdrv_sd_state */
+       memcpy(s, old_s, sizeof(BDRVSheepdogState));
+       qemu_free(buf);
+       qemu_free(old_s);
+
+       error_report("failed to open. recover old bdrv_sd_state.\n");
+
+       return ret;
+}
+
+static int sd_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
+{
+       /* FIXME: Delete specified snapshot id.  */
+       return 0;
+}
+
+#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
+#define BITS_PER_BYTE          8
+#define BITS_TO_LONGS(nr)      DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
+#define DECLARE_BITMAP(name,bits) \
+       unsigned long name[BITS_TO_LONGS(bits)]
+
+#define BITS_PER_LONG (BITS_PER_BYTE * sizeof(long))
+
+static inline int test_bit(unsigned int nr, const unsigned long *addr)
+{
+       return ((1UL << (nr % BITS_PER_LONG)) &
+               (((unsigned long *)addr)[nr / BITS_PER_LONG])) != 0;
+}
+
+static int sd_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
+{
+       BDRVSheepdogState *s = bs->opaque;
+       SheepdogReq req;
+       int i, fd, nr = 1024, ret, max = BITS_TO_LONGS(SD_NR_VDIS) * 
sizeof(long);
+       QEMUSnapshotInfo *sn_tab = NULL;
+       unsigned wlen, rlen;
+       int found = 0;
+       static SheepdogInode inode;
+       unsigned long *vdi_inuse;
+       unsigned int start_nr;
+
+       vdi_inuse = qemu_malloc(max);
+
+       fd = connect_to_sdog(s->addr);
+       if (fd < 0) {
+               goto out;
+       }
+
+       rlen = max;
+       wlen = 0;
+
+       memset(&req, 0, sizeof(req));
+
+       req.opcode = SD_OP_READ_VDIS;
+       req.data_length = max;
+
+       ret = do_req(fd, (SheepdogReq *)&req, vdi_inuse, &wlen, &rlen);
+
+       close(fd);
+       if (ret) {
+               goto out;
+       }
+
+       sn_tab = qemu_mallocz(nr * sizeof(*sn_tab));
+
+       start_nr = fnv_64a_buf(s->name, strlen(s->name), FNV1A_64_INIT) & 
(SD_NR_VDIS - 1);
+
+       fd = connect_to_sdog(s->addr);
+       if (fd < 0) {
+               error_report("failed to connect\n");
+               goto out;
+       }
+
+       /* TODO: round up */
+       for (i = start_nr; i < SD_NR_VDIS && found < nr; i++) {
+               if (!test_bit(i, vdi_inuse)) {
+                       break;
+               }
+
+               /* we don't need to read entire object */
+               ret = read_object(fd, (char *)&inode, vid_to_vdi_oid(i),
+                                 0, SD_INODE_SIZE - sizeof(inode.data_vdi_id), 
0);
+
+               if (ret) {
+                       continue;
+               }
+
+               if (!strcmp(inode.name, s->name) && inode.snap_ctime) {
+                       sn_tab[found].date_sec = inode.snap_ctime >> 32;
+                       sn_tab[found].date_nsec = inode.snap_ctime & 0xffffffff;
+                       sn_tab[found].vm_state_size = inode.vm_state_size;
+                       sn_tab[found].vm_clock_nsec = inode.vm_clock_nsec;
+
+                       snprintf(sn_tab[found].id_str, 
sizeof(sn_tab[found].id_str), "%u",
+                                inode.snap_id);
+                       found++;
+               }
+       }
+
+       close(fd);
+out:
+       *psn_tab = sn_tab;
+
+       qemu_free(vdi_inuse);
+
+       return found;
+}
+
+static int do_load_save_vmstate(BDRVSheepdogState *s, uint8_t *data,
+                               int64_t pos, int size, int load)
+{
+       int fd, create;
+       int ret = 0;
+       unsigned int data_len;
+       uint64_t vmstate_oid;
+       uint32_t vdi_index;
+       uint64_t offset;
+
+       fd = connect_to_sdog(s->addr);
+       if (fd < 0) {
+               ret = -EIO;
+               goto cleanup;
+       }
+
+       while (size) {
+               vdi_index = pos / SD_DATA_OBJ_SIZE;
+               offset = pos % SD_DATA_OBJ_SIZE;
+
+               data_len = min_t(unsigned int, size, SD_DATA_OBJ_SIZE);
+
+               vmstate_oid = vid_to_vmstate_oid(s->inode.vdi_id, vdi_index);
+
+               create = (offset == 0);
+               if (load) {
+                       ret = read_object(fd, (char *)data, vmstate_oid,
+                                         s->inode.nr_copies, data_len, offset);
+               } else {
+                       ret = write_object(fd, (char *)data, vmstate_oid,
+                                          s->inode.nr_copies, data_len, 
offset, create);
+               }
+
+               if (ret < 0) {
+                       error_report("failed to save vmstate %m\n");
+                       ret = -EIO;
+                       goto cleanup;
+               }
+
+               pos += data_len;
+               size -= data_len;
+               ret += data_len;
+       }
+cleanup:
+       close(fd);
+       return ret;
+}
+
+static int sd_save_vmstate(BlockDriverState *bs, const uint8_t *data,
+                          int64_t pos, int size)
+{
+       BDRVSheepdogState *s = bs->opaque;
+
+       return do_load_save_vmstate(s, (uint8_t *)data, pos, size, 0);
+}
+
+static int sd_load_vmstate(BlockDriverState *bs, uint8_t *data,
+                          int64_t pos, int size)
+{
+       BDRVSheepdogState *s = bs->opaque;
+
+       return do_load_save_vmstate(s, data, pos, size, 1);
+}
+
+
+static QEMUOptionParameter sd_create_options[] = {
+       {
+               .name = BLOCK_OPT_SIZE,
+               .type = OPT_SIZE,
+               .help = "Virtual disk size"
+       },
+       {
+               .name = BLOCK_OPT_BACKING_FILE,
+               .type = OPT_STRING,
+               .help = "File name of a base image"
+       },
+       { NULL }
+};
+
+BlockDriver bdrv_sheepdog = {
+       .format_name    = "sheepdog",
+       .protocol_name  = "sheepdog",
+       .instance_size  = sizeof(BDRVSheepdogState),
+       .bdrv_file_open = sd_open,
+       .bdrv_close     = sd_close,
+       .bdrv_create    = sd_create,
+
+       .bdrv_aio_readv     = sd_aio_readv,
+       .bdrv_aio_writev    = sd_aio_writev,
+
+       .bdrv_snapshot_create   = sd_snapshot_create,
+       .bdrv_snapshot_goto     = sd_snapshot_goto,
+       .bdrv_snapshot_delete   = sd_snapshot_delete,
+       .bdrv_snapshot_list     = sd_snapshot_list,
+
+       .bdrv_save_vmstate  = sd_save_vmstate,
+       .bdrv_load_vmstate  = sd_load_vmstate,
+
+       .create_options = sd_create_options,
+};
+
+static void bdrv_sheepdog_init(void)
+{
+       bdrv_register(&bdrv_sheepdog);
+}
+block_init(bdrv_sheepdog_init);
-- 
1.5.6.5




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