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qemu/block/rbd.c

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/*
* QEMU Block driver for RADOS (Ceph)
*
* Copyright (C) 2010-2011 Christian Brunner <chb@muc.de>,
* Josh Durgin <josh.durgin@dreamhost.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/
#include <inttypes.h>
#include "qemu-common.h"
#include "qemu-error.h"
#include "block_int.h"
#include <rbd/librbd.h>
/*
* When specifying the image filename use:
*
* rbd:poolname/devicename[@snapshotname][:option1=value1[:option2=value2...]]
*
* poolname must be the name of an existing rados pool.
*
* devicename is the name of the rbd image.
*
* Each option given is used to configure rados, and may be any valid
* Ceph option, "id", or "conf".
*
* The "id" option indicates what user we should authenticate as to
* the Ceph cluster. If it is excluded we will use the Ceph default
* (normally 'admin').
*
* The "conf" option specifies a Ceph configuration file to read. If
* it is not specified, we will read from the default Ceph locations
* (e.g., /etc/ceph/ceph.conf). To avoid reading _any_ configuration
* file, specify conf=/dev/null.
*
* Configuration values containing :, @, or = can be escaped with a
* leading "\".
*/
#define OBJ_MAX_SIZE (1UL << OBJ_DEFAULT_OBJ_ORDER)
#define RBD_MAX_CONF_NAME_SIZE 128
#define RBD_MAX_CONF_VAL_SIZE 512
#define RBD_MAX_CONF_SIZE 1024
#define RBD_MAX_POOL_NAME_SIZE 128
#define RBD_MAX_SNAP_NAME_SIZE 128
#define RBD_MAX_SNAPS 100
typedef struct RBDAIOCB {
BlockDriverAIOCB common;
QEMUBH *bh;
int ret;
QEMUIOVector *qiov;
char *bounce;
int write;
int64_t sector_num;
int error;
struct BDRVRBDState *s;
int cancelled;
} RBDAIOCB;
typedef struct RADOSCB {
int rcbid;
RBDAIOCB *acb;
struct BDRVRBDState *s;
int done;
int64_t size;
char *buf;
int ret;
} RADOSCB;
#define RBD_FD_READ 0
#define RBD_FD_WRITE 1
typedef struct BDRVRBDState {
int fds[2];
rados_t cluster;
rados_ioctx_t io_ctx;
rbd_image_t image;
char name[RBD_MAX_IMAGE_NAME_SIZE];
int qemu_aio_count;
char *snap;
int event_reader_pos;
RADOSCB *event_rcb;
} BDRVRBDState;
static void rbd_aio_bh_cb(void *opaque);
static int qemu_rbd_next_tok(char *dst, int dst_len,
char *src, char delim,
const char *name,
char **p)
{
int l;
char *end;
*p = NULL;
if (delim != '\0') {
for (end = src; *end; ++end) {
if (*end == delim) {
break;
}
if (*end == '\\' && end[1] != '\0') {
end++;
}
}
if (*end == delim) {
*p = end + 1;
*end = '\0';
}
}
l = strlen(src);
if (l >= dst_len) {
error_report("%s too long", name);
return -EINVAL;
} else if (l == 0) {
error_report("%s too short", name);
return -EINVAL;
}
pstrcpy(dst, dst_len, src);
return 0;
}
static void qemu_rbd_unescape(char *src)
{
char *p;
for (p = src; *src; ++src, ++p) {
if (*src == '\\' && src[1] != '\0') {
src++;
}
*p = *src;
}
*p = '\0';
}
static int qemu_rbd_parsename(const char *filename,
char *pool, int pool_len,
char *snap, int snap_len,
char *name, int name_len,
char *conf, int conf_len)
{
const char *start;
char *p, *buf;
int ret;
if (!strstart(filename, "rbd:", &start)) {
return -EINVAL;
}
buf = g_strdup(start);
p = buf;
*snap = '\0';
*conf = '\0';
ret = qemu_rbd_next_tok(pool, pool_len, p, '/', "pool name", &p);
if (ret < 0 || !p) {
ret = -EINVAL;
goto done;
}
qemu_rbd_unescape(pool);
if (strchr(p, '@')) {
ret = qemu_rbd_next_tok(name, name_len, p, '@', "object name", &p);
if (ret < 0) {
goto done;
}
ret = qemu_rbd_next_tok(snap, snap_len, p, ':', "snap name", &p);
qemu_rbd_unescape(snap);
} else {
ret = qemu_rbd_next_tok(name, name_len, p, ':', "object name", &p);
}
qemu_rbd_unescape(name);
if (ret < 0 || !p) {
goto done;
}
ret = qemu_rbd_next_tok(conf, conf_len, p, '\0', "configuration", &p);
done:
g_free(buf);
return ret;
}
static char *qemu_rbd_parse_clientname(const char *conf, char *clientname)
{
const char *p = conf;
while (*p) {
int len;
const char *end = strchr(p, ':');
if (end) {
len = end - p;
} else {
len = strlen(p);
}
if (strncmp(p, "id=", 3) == 0) {
len -= 3;
strncpy(clientname, p + 3, len);
clientname[len] = '\0';
return clientname;
}
if (end == NULL) {
break;
}
p = end + 1;
}
return NULL;
}
static int qemu_rbd_set_conf(rados_t cluster, const char *conf)
{
char *p, *buf;
char name[RBD_MAX_CONF_NAME_SIZE];
char value[RBD_MAX_CONF_VAL_SIZE];
int ret = 0;
buf = g_strdup(conf);
p = buf;
while (p) {
ret = qemu_rbd_next_tok(name, sizeof(name), p,
'=', "conf option name", &p);
if (ret < 0) {
break;
}
qemu_rbd_unescape(name);
if (!p) {
error_report("conf option %s has no value", name);
ret = -EINVAL;
break;
}
ret = qemu_rbd_next_tok(value, sizeof(value), p,
':', "conf option value", &p);
if (ret < 0) {
break;
}
qemu_rbd_unescape(value);
if (strcmp(name, "conf") == 0) {
ret = rados_conf_read_file(cluster, value);
if (ret < 0) {
error_report("error reading conf file %s", value);
break;
}
} else if (strcmp(name, "id") == 0) {
/* ignore, this is parsed by qemu_rbd_parse_clientname() */
} else {
ret = rados_conf_set(cluster, name, value);
if (ret < 0) {
error_report("invalid conf option %s", name);
ret = -EINVAL;
break;
}
}
}
g_free(buf);
return ret;
}
static int qemu_rbd_create(const char *filename, QEMUOptionParameter *options)
{
int64_t bytes = 0;
int64_t objsize;
int obj_order = 0;
char pool[RBD_MAX_POOL_NAME_SIZE];
char name[RBD_MAX_IMAGE_NAME_SIZE];
char snap_buf[RBD_MAX_SNAP_NAME_SIZE];
char conf[RBD_MAX_CONF_SIZE];
char clientname_buf[RBD_MAX_CONF_SIZE];
char *clientname;
rados_t cluster;
rados_ioctx_t io_ctx;
int ret;
if (qemu_rbd_parsename(filename, pool, sizeof(pool),
snap_buf, sizeof(snap_buf),
name, sizeof(name),
conf, sizeof(conf)) < 0) {
return -EINVAL;
}
/* Read out options */
while (options && options->name) {
if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
bytes = options->value.n;
} else if (!strcmp(options->name, BLOCK_OPT_CLUSTER_SIZE)) {
if (options->value.n) {
objsize = options->value.n;
if ((objsize - 1) & objsize) { /* not a power of 2? */
error_report("obj size needs to be power of 2");
return -EINVAL;
}
if (objsize < 4096) {
error_report("obj size too small");
return -EINVAL;
}
obj_order = ffs(objsize) - 1;
}
}
options++;
}
clientname = qemu_rbd_parse_clientname(conf, clientname_buf);
if (rados_create(&cluster, clientname) < 0) {
error_report("error initializing");
return -EIO;
}
if (strstr(conf, "conf=") == NULL) {
/* try default location, but ignore failure */
rados_conf_read_file(cluster, NULL);
}
if (conf[0] != '\0' &&
qemu_rbd_set_conf(cluster, conf) < 0) {
error_report("error setting config options");
rados_shutdown(cluster);
return -EIO;
}
if (rados_connect(cluster) < 0) {
error_report("error connecting");
rados_shutdown(cluster);
return -EIO;
}
if (rados_ioctx_create(cluster, pool, &io_ctx) < 0) {
error_report("error opening pool %s", pool);
rados_shutdown(cluster);
return -EIO;
}
ret = rbd_create(io_ctx, name, bytes, &obj_order);
rados_ioctx_destroy(io_ctx);
rados_shutdown(cluster);
return ret;
}
/*
* This aio completion is being called from qemu_rbd_aio_event_reader()
* and runs in qemu context. It schedules a bh, but just in case the aio
* was not cancelled before.
*/
static void qemu_rbd_complete_aio(RADOSCB *rcb)
{
RBDAIOCB *acb = rcb->acb;
int64_t r;
if (acb->cancelled) {
qemu_vfree(acb->bounce);
qemu_aio_release(acb);
goto done;
}
r = rcb->ret;
if (acb->write) {
if (r < 0) {
acb->ret = r;
acb->error = 1;
} else if (!acb->error) {
acb->ret = rcb->size;
}
} else {
if (r < 0) {
memset(rcb->buf, 0, rcb->size);
acb->ret = r;
acb->error = 1;
} else if (r < rcb->size) {
memset(rcb->buf + r, 0, rcb->size - r);
if (!acb->error) {
acb->ret = rcb->size;
}
} else if (!acb->error) {
acb->ret = r;
}
}
/* Note that acb->bh can be NULL in case where the aio was cancelled */
acb->bh = qemu_bh_new(rbd_aio_bh_cb, acb);
qemu_bh_schedule(acb->bh);
done:
g_free(rcb);
}
/*
* aio fd read handler. It runs in the qemu context and calls the
* completion handling of completed rados aio operations.
*/
static void qemu_rbd_aio_event_reader(void *opaque)
{
BDRVRBDState *s = opaque;
ssize_t ret;
do {
char *p = (char *)&s->event_rcb;
/* now read the rcb pointer that was sent from a non qemu thread */
ret = read(s->fds[RBD_FD_READ], p + s->event_reader_pos,
sizeof(s->event_rcb) - s->event_reader_pos);
if (ret > 0) {
s->event_reader_pos += ret;
if (s->event_reader_pos == sizeof(s->event_rcb)) {
s->event_reader_pos = 0;
qemu_rbd_complete_aio(s->event_rcb);
s->qemu_aio_count--;
}
}
} while (ret < 0 && errno == EINTR);
}
static int qemu_rbd_aio_flush_cb(void *opaque)
{
BDRVRBDState *s = opaque;
return (s->qemu_aio_count > 0);
}
static int qemu_rbd_open(BlockDriverState *bs, const char *filename, int flags)
{
BDRVRBDState *s = bs->opaque;
char pool[RBD_MAX_POOL_NAME_SIZE];
char snap_buf[RBD_MAX_SNAP_NAME_SIZE];
char conf[RBD_MAX_CONF_SIZE];
char clientname_buf[RBD_MAX_CONF_SIZE];
char *clientname;
int r;
if (qemu_rbd_parsename(filename, pool, sizeof(pool),
snap_buf, sizeof(snap_buf),
s->name, sizeof(s->name),
conf, sizeof(conf)) < 0) {
return -EINVAL;
}
clientname = qemu_rbd_parse_clientname(conf, clientname_buf);
r = rados_create(&s->cluster, clientname);
if (r < 0) {
error_report("error initializing");
return r;
}
s->snap = NULL;
if (snap_buf[0] != '\0') {
s->snap = g_strdup(snap_buf);
}
if (strstr(conf, "conf=") == NULL) {
/* try default location, but ignore failure */
rados_conf_read_file(s->cluster, NULL);
}
if (conf[0] != '\0') {
r = qemu_rbd_set_conf(s->cluster, conf);
if (r < 0) {
error_report("error setting config options");
goto failed_shutdown;
}
}
r = rados_connect(s->cluster);
if (r < 0) {
error_report("error connecting");
goto failed_shutdown;
}
r = rados_ioctx_create(s->cluster, pool, &s->io_ctx);
if (r < 0) {
error_report("error opening pool %s", pool);
goto failed_shutdown;
}
r = rbd_open(s->io_ctx, s->name, &s->image, s->snap);
if (r < 0) {
error_report("error reading header from %s", s->name);
goto failed_open;
}
bs->read_only = (s->snap != NULL);
s->event_reader_pos = 0;
r = qemu_pipe(s->fds);
if (r < 0) {
error_report("error opening eventfd");
goto failed;
}
fcntl(s->fds[0], F_SETFL, O_NONBLOCK);
fcntl(s->fds[1], F_SETFL, O_NONBLOCK);
qemu_aio_set_fd_handler(s->fds[RBD_FD_READ], qemu_rbd_aio_event_reader,
NULL, qemu_rbd_aio_flush_cb, NULL, s);
return 0;
failed:
rbd_close(s->image);
failed_open:
rados_ioctx_destroy(s->io_ctx);
failed_shutdown:
rados_shutdown(s->cluster);
g_free(s->snap);
return r;
}
static void qemu_rbd_close(BlockDriverState *bs)
{
BDRVRBDState *s = bs->opaque;
close(s->fds[0]);
close(s->fds[1]);
qemu_aio_set_fd_handler(s->fds[RBD_FD_READ], NULL , NULL, NULL, NULL,
NULL);
rbd_close(s->image);
rados_ioctx_destroy(s->io_ctx);
g_free(s->snap);
rados_shutdown(s->cluster);
}
/*
* Cancel aio. Since we don't reference acb in a non qemu threads,
* it is safe to access it here.
*/
static void qemu_rbd_aio_cancel(BlockDriverAIOCB *blockacb)
{
RBDAIOCB *acb = (RBDAIOCB *) blockacb;
acb->cancelled = 1;
}
static AIOPool rbd_aio_pool = {
.aiocb_size = sizeof(RBDAIOCB),
.cancel = qemu_rbd_aio_cancel,
};
static int qemu_rbd_send_pipe(BDRVRBDState *s, RADOSCB *rcb)
{
int ret = 0;
while (1) {
fd_set wfd;
int fd = s->fds[RBD_FD_WRITE];
/* send the op pointer to the qemu thread that is responsible
for the aio/op completion. Must do it in a qemu thread context */
ret = write(fd, (void *)&rcb, sizeof(rcb));
if (ret >= 0) {
break;
}
if (errno == EINTR) {
continue;
}
if (errno != EAGAIN) {
break;
}
FD_ZERO(&wfd);
FD_SET(fd, &wfd);
do {
ret = select(fd + 1, NULL, &wfd, NULL, NULL);
} while (ret < 0 && errno == EINTR);
}
return ret;
}
/*
* This is the callback function for rbd_aio_read and _write
*
* Note: this function is being called from a non qemu thread so
* we need to be careful about what we do here. Generally we only
* write to the block notification pipe, and do the rest of the
* io completion handling from qemu_rbd_aio_event_reader() which
* runs in a qemu context.
*/
static void rbd_finish_aiocb(rbd_completion_t c, RADOSCB *rcb)
{
int ret;
rcb->ret = rbd_aio_get_return_value(c);
rbd_aio_release(c);
ret = qemu_rbd_send_pipe(rcb->s, rcb);
if (ret < 0) {
error_report("failed writing to acb->s->fds");
g_free(rcb);
}
}
/* Callback when all queued rbd_aio requests are complete */
static void rbd_aio_bh_cb(void *opaque)
{
RBDAIOCB *acb = opaque;
if (!acb->write) {
qemu_iovec_from_buffer(acb->qiov, acb->bounce, acb->qiov->size);
}
qemu_vfree(acb->bounce);
acb->common.cb(acb->common.opaque, (acb->ret > 0 ? 0 : acb->ret));
qemu_bh_delete(acb->bh);
acb->bh = NULL;
qemu_aio_release(acb);
}
static BlockDriverAIOCB *rbd_aio_rw_vector(BlockDriverState *bs,
int64_t sector_num,
QEMUIOVector *qiov,
int nb_sectors,
BlockDriverCompletionFunc *cb,
void *opaque, int write)
{
RBDAIOCB *acb;
RADOSCB *rcb;
rbd_completion_t c;
int64_t off, size;
char *buf;
int r;
BDRVRBDState *s = bs->opaque;
acb = qemu_aio_get(&rbd_aio_pool, bs, cb, opaque);
acb->write = write;
acb->qiov = qiov;
acb->bounce = qemu_blockalign(bs, qiov->size);
acb->ret = 0;
acb->error = 0;
acb->s = s;
acb->cancelled = 0;
acb->bh = NULL;
if (write) {
qemu_iovec_to_buffer(acb->qiov, acb->bounce);
}
buf = acb->bounce;
off = sector_num * BDRV_SECTOR_SIZE;
size = nb_sectors * BDRV_SECTOR_SIZE;
s->qemu_aio_count++; /* All the RADOSCB */
rcb = g_malloc(sizeof(RADOSCB));
rcb->done = 0;
rcb->acb = acb;
rcb->buf = buf;
rcb->s = acb->s;
rcb->size = size;
r = rbd_aio_create_completion(rcb, (rbd_callback_t) rbd_finish_aiocb, &c);
if (r < 0) {
goto failed;
}
if (write) {
r = rbd_aio_write(s->image, off, size, buf, c);
} else {
r = rbd_aio_read(s->image, off, size, buf, c);
}
if (r < 0) {
goto failed;
}
return &acb->common;
failed:
g_free(rcb);
s->qemu_aio_count--;
qemu_aio_release(acb);
return NULL;
}
static BlockDriverAIOCB *qemu_rbd_aio_readv(BlockDriverState *bs,
int64_t sector_num,
QEMUIOVector *qiov,
int nb_sectors,
BlockDriverCompletionFunc *cb,
void *opaque)
{
return rbd_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 0);
}
static BlockDriverAIOCB *qemu_rbd_aio_writev(BlockDriverState *bs,
int64_t sector_num,
QEMUIOVector *qiov,
int nb_sectors,
BlockDriverCompletionFunc *cb,
void *opaque)
{
return rbd_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 1);
}
static int qemu_rbd_co_flush(BlockDriverState *bs)
{
#if LIBRBD_VERSION_CODE >= LIBRBD_VERSION(0, 1, 1)
/* rbd_flush added in 0.1.1 */
BDRVRBDState *s = bs->opaque;
return rbd_flush(s->image);
#else
return 0;
#endif
}
static int qemu_rbd_getinfo(BlockDriverState *bs, BlockDriverInfo *bdi)
{
BDRVRBDState *s = bs->opaque;
rbd_image_info_t info;
int r;
r = rbd_stat(s->image, &info, sizeof(info));
if (r < 0) {
return r;
}
bdi->cluster_size = info.obj_size;
return 0;
}
static int64_t qemu_rbd_getlength(BlockDriverState *bs)
{
BDRVRBDState *s = bs->opaque;
rbd_image_info_t info;
int r;
r = rbd_stat(s->image, &info, sizeof(info));
if (r < 0) {
return r;
}
return info.size;
}
static int qemu_rbd_truncate(BlockDriverState *bs, int64_t offset)
{
BDRVRBDState *s = bs->opaque;
int r;
r = rbd_resize(s->image, offset);
if (r < 0) {
return r;
}
return 0;
}
static int qemu_rbd_snap_create(BlockDriverState *bs,
QEMUSnapshotInfo *sn_info)
{
BDRVRBDState *s = bs->opaque;
int r;
if (sn_info->name[0] == '\0') {
return -EINVAL; /* we need a name for rbd snapshots */
}
/*
* rbd snapshots are using the name as the user controlled unique identifier
* we can't use the rbd snapid for that purpose, as it can't be set
*/
if (sn_info->id_str[0] != '\0' &&
strcmp(sn_info->id_str, sn_info->name) != 0) {
return -EINVAL;
}
if (strlen(sn_info->name) >= sizeof(sn_info->id_str)) {
return -ERANGE;
}
r = rbd_snap_create(s->image, sn_info->name);
if (r < 0) {
error_report("failed to create snap: %s", strerror(-r));
return r;
}
return 0;
}
static int qemu_rbd_snap_list(BlockDriverState *bs,
QEMUSnapshotInfo **psn_tab)
{
BDRVRBDState *s = bs->opaque;
QEMUSnapshotInfo *sn_info, *sn_tab = NULL;
int i, snap_count;
rbd_snap_info_t *snaps;
int max_snaps = RBD_MAX_SNAPS;
do {
snaps = g_malloc(sizeof(*snaps) * max_snaps);
snap_count = rbd_snap_list(s->image, snaps, &max_snaps);
if (snap_count < 0) {
g_free(snaps);
}
} while (snap_count == -ERANGE);
if (snap_count <= 0) {
goto done;
}
sn_tab = g_malloc0(snap_count * sizeof(QEMUSnapshotInfo));
for (i = 0; i < snap_count; i++) {
const char *snap_name = snaps[i].name;
sn_info = sn_tab + i;
pstrcpy(sn_info->id_str, sizeof(sn_info->id_str), snap_name);
pstrcpy(sn_info->name, sizeof(sn_info->name), snap_name);
sn_info->vm_state_size = snaps[i].size;
sn_info->date_sec = 0;
sn_info->date_nsec = 0;
sn_info->vm_clock_nsec = 0;
}
rbd_snap_list_end(snaps);
done:
*psn_tab = sn_tab;
return snap_count;
}
static QEMUOptionParameter qemu_rbd_create_options[] = {
{
.name = BLOCK_OPT_SIZE,
.type = OPT_SIZE,
.help = "Virtual disk size"
},
{
.name = BLOCK_OPT_CLUSTER_SIZE,
.type = OPT_SIZE,
.help = "RBD object size"
},
{NULL}
};
static BlockDriver bdrv_rbd = {
.format_name = "rbd",
.instance_size = sizeof(BDRVRBDState),
.bdrv_file_open = qemu_rbd_open,
.bdrv_close = qemu_rbd_close,
.bdrv_create = qemu_rbd_create,
.bdrv_get_info = qemu_rbd_getinfo,
.create_options = qemu_rbd_create_options,
.bdrv_getlength = qemu_rbd_getlength,
.bdrv_truncate = qemu_rbd_truncate,
.protocol_name = "rbd",
.bdrv_aio_readv = qemu_rbd_aio_readv,
.bdrv_aio_writev = qemu_rbd_aio_writev,
.bdrv_co_flush_to_disk = qemu_rbd_co_flush,
.bdrv_snapshot_create = qemu_rbd_snap_create,
.bdrv_snapshot_list = qemu_rbd_snap_list,
};
static void bdrv_rbd_init(void)
{
bdrv_register(&bdrv_rbd);
}
block_init(bdrv_rbd_init);
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