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[Qemu-devel] Re: [RFC PATCH v4 3/3] block: add sheepdog driver for distr
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From: |
Kevin Wolf |
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Subject: |
[Qemu-devel] Re: [RFC PATCH v4 3/3] block: add sheepdog driver for distributed storage support |
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Date: |
Wed, 02 Jun 2010 15:55:42 +0200 |
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User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100430 Fedora/3.0.4-2.fc12 Thunderbird/3.0.4 |
Am 28.05.2010 04:44, schrieb MORITA Kazutaka:
> 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 | 1835
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 1836 insertions(+), 1 deletions(-)
> create mode 100644 block/sheepdog.c
One general thing: The code uses some mix of spaces and tabs for
indentation, with the greatest part using tabs. According to
CODING_STYLE it should consistently use four spaces instead.
> diff --git a/Makefile.objs b/Makefile.objs
> index 1a942e5..527a754 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..68545e8
> --- /dev/null
> +++ b/block/sheepdog.c
> @@ -0,0 +1,1835 @@
> +/*
> + * 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];
Wow, this is a huge array. :-)
So Sheepdog has a fixed limit of 16 TB, right?
> +} 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;
> +}
Does this provide the right semantics? You haven't really cancelled the
request, but you pretend to. So you actually complete the request in the
background and then throw the return code away.
I seem to remember that posix-aio-compat.c waits at this point for
completion of the requests, calls the callbacks and only afterwards
returns from aio_cancel when no more requests are in flight.
Or if you can really cancel requests, it would be the best option, of
course.
> +
> +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)
I've spent at least 15 minutes figuring out what this function does. I
think I've got it now more or less, but I've come to the conclusion that
this code needs more comments.
I'd suggest to add a header comment to all non-trivial functions and
maybe somewhere on the top a general description of how things work.
As far as I understood now, there are basically two parts of request
handling:
1. The request is sent to the server. Its AIOCB is saved in a list in
the BDRVSheepdogState. It doesn't pass a callback or anything for the
completion.
2. aio_read_response is registered as a fd handler to the sheepdog
connection. When the server responds, it searches the right AIOCB in the
list and the second part of request handling starts.
do_send_recv is the function that is used to do all communication with
the server. The iov stuff looks like it's only used for some data, but
seems this is not true - it's also used for the metadata of the protocol.
Did I understand it right so far?
> +{
> + 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++;
> + }
You're counting the number of elements in the iov here. qemu_iovec would
already have these (and also len), wouldn't it make sense to use it as
the abstraction? Though I'm not sure where these iovecs come from, so
the answer might be no.
> +
> + 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);
This smells like buffer overflows. In practice it's s->addr for all
callers and I think this values comes indirectly from filename in
sd_open - for which I didn't find a length check, so it could overflow
indeed.
> +
> + 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;
Why do you declare an otherwise unused variable hdr, take a pointer to
it and cast it to an incompatible type? This is scary.
> + 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));
This cast looks scary, too. But do_read wants a void* anyway, so it's
not even necessary. Please drop it.
> + 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;
Unnecessary cast.
> +
> + 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");
%m is Linux specific, as far as I know.
> + 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;
> + }
Is it really necessary to do Sheepdog specific stuff here? With other
formats I can use any format I like for a backing file. VMDK did assume
that backing files could only be VMDK initially, but it was considered a
bug.
If Sheepdog can't handle other image formats (e.g. because it can't
communicate that a request touches unallocated space), you need to check
this at least an return an error if something else is used.
One more thing, I'll ask the same as for Ceph here: Do you have any
specific tests for Sheepdog that could be used or should we try to use
generic qemu-iotests cases?
Kevin
- [Qemu-devel] Re: [RFC PATCH v4 3/3] block: add sheepdog driver for distributed storage support,
Kevin Wolf <=