Implement QEMU block driver
This commit is contained in:
Vitaliy Filippov
+352
@@ -0,0 +1,352 @@
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// QEMU block driver
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#define _GNU_SOURCE
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#include "qemu/osdep.h"
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#include "qemu/units.h"
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#include "block/block_int.h"
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#include "block/qdict.h"
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#include "qapi/error.h"
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#include "qapi/qmp/qdict.h"
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#include "qapi/qmp/qerror.h"
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#include "qemu/uri.h"
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#include "qemu/error-report.h"
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#include "qemu/module.h"
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#include "qemu/option.h"
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#include "qemu/cutils.h"
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#include "qemu_proxy.h"
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typedef struct FalconClient
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{
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void *proxy;
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const char *etcd_host;
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const char *etcd_prefix;
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uint64_t inode;
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uint64_t size;
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int readonly;
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QemuMutex mutex;
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} FalconClient;
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typedef struct FalconRPC
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{
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BlockDriverState *bs;
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Coroutine *co;
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QEMUIOVector *iov;
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int ret;
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int complete;
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} FalconRPC;
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static char *qemu_rbd_next_tok(char *src, char delim, char **p)
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{
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char *end;
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*p = NULL;
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for (end = src; *end; ++end)
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{
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if (*end == delim)
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break;
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if (*end == '\\' && end[1] != '\0')
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end++;
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}
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if (*end == delim)
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{
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*p = end + 1;
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*end = '\0';
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}
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return src;
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}
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static void qemu_rbd_unescape(char *src)
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{
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char *p;
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for (p = src; *src; ++src, ++p)
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{
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if (*src == '\\' && src[1] != '\0')
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src++;
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*p = *src;
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}
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*p = '\0';
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}
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// falcon[:key=value]*
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// falcon:etcd_host=127.0.0.1:inode=1
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static void falcon_parse_filename(const char *filename, QDict *options, Error **errp)
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{
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const char *start;
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char *p, *buf;
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if (!strstart(filename, "falcon:", &start))
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{
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error_setg(errp, "File name must start with 'falcon:'");
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return;
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}
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buf = g_strdup(start);
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p = buf;
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// The following are all key/value pairs
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while (p)
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{
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char *name, *value;
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name = qemu_rbd_next_tok(p, '=', &p);
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if (!p)
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{
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error_setg(errp, "conf option %s has no value", name);
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break;
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}
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qemu_rbd_unescape(name);
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value = qemu_rbd_next_tok(p, ':', &p);
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qemu_rbd_unescape(value);
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if (!strcmp(name, "inode") || !strcmp(name, "size"))
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{
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unsigned long long num_val;
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if (parse_uint_full(value, &num_val, 0))
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{
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error_setg(errp, "Illegal %s: %s", name, value);
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goto out;
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}
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qdict_put_int(options, name, num_val);
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}
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else
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{
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qdict_put_str(options, name, value);
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}
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}
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if (!qdict_get_int(options, "inode"))
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{
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error_setg(errp, "inode is missing");
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goto out;
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}
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if (!qdict_get_int(options, "size"))
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{
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error_setg(errp, "size is missing");
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goto out;
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}
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if (!qdict_get_int(options, "etcd_host"))
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{
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error_setg(errp, "etcd_host is missing");
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goto out;
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}
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out:
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g_free(buf);
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return;
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}
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static int falcon_file_open(BlockDriverState *bs, QDict *options, int flags, Error **errp)
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{
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FalconClient *client = bs->opaque;
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int64_t ret = 0;
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client->etcd_host = qdict_get_try_str(options, "etcd_host");
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client->etcd_prefix = qdict_get_try_str(options, "etcd_prefix");
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client->inode = qdict_get_int(options, "inode");
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client->size = qdict_get_int(options, "size");
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client->readonly = (flags & BDRV_O_RDWR) ? 1 : 0;
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client->proxy = falcon_proxy_create(client->etcd_host, client->etcd_prefix);
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//client->aio_context = bdrv_get_aio_context(bs);
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bs->total_sectors = client->size / BDRV_SECTOR_SIZE;
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return ret;
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}
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static void falcon_close(BlockDriverState *bs)
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{
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FalconClient *client = bs->opaque;
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falcon_proxy_destroy(client->proxy);
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}
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static int falcon_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
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{
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bsz->phys = 4096;
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bsz->log = 4096;
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return 0;
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}
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static int coroutine_fn falcon_co_create_opts(BlockDriver *drv, const char *url, QemuOpts *opts, Error **errp)
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{
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QDict *options;
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int ret;
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options = qdict_new();
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falcon_parse_filename(url, options, errp);
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if (errp)
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{
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ret = -1;
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goto out;
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}
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// inodes don't require creation in Falcon. FIXME: They will when there will be some metadata
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ret = 0;
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out:
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qobject_unref(options);
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return ret;
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}
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static int coroutine_fn falcon_co_truncate(BlockDriverState *bs, int64_t offset, bool exact, PreallocMode prealloc, Error **errp)
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{
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FalconClient *client = bs->opaque;
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if (prealloc != PREALLOC_MODE_OFF)
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{
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error_setg(errp, "Unsupported preallocation mode '%s'", PreallocMode_str(prealloc));
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return -ENOTSUP;
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}
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// TODO: Resize inode to <offset> bytes
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client->size = offset / BDRV_SECTOR_SIZE;
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return 0;
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}
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static int falcon_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
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{
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bdi->cluster_size = 4096;
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return 0;
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}
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static int64_t falcon_getlength(BlockDriverState *bs)
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{
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FalconClient *client = bs->opaque;
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return client->size;
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}
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static int64_t falcon_get_allocated_file_size(BlockDriverState *bs)
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{
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return 0;
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}
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static void falcon_co_init_task(BlockDriverState *bs, FalconRPC *task)
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{
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*task = (FalconRPC) {
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.co = qemu_coroutine_self(),
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.bs = bs,
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};
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}
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static void falcon_co_generic_bh_cb(int retval, void *opaque)
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{
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FalconRPC *task = opaque;
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task->ret = retval;
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task->complete = 1;
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aio_co_wake(task->co);
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}
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static int coroutine_fn falcon_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes, QEMUIOVector *iov, int flags)
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{
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FalconClient *client = bs->opaque;
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FalconRPC task;
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falcon_co_init_task(bs, &task);
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task.iov = iov;
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qemu_mutex_lock(&client->mutex);
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falcon_proxy_rw(0, client->proxy, client->inode, offset, bytes, iov->iov, iov->niov, falcon_co_generic_bh_cb, &task);
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qemu_mutex_unlock(&client->mutex);
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while (!task.complete)
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{
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qemu_coroutine_yield();
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}
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return task.ret;
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}
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static int coroutine_fn falcon_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes, QEMUIOVector *iov, int flags)
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{
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FalconClient *client = bs->opaque;
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FalconRPC task;
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falcon_co_init_task(bs, &task);
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task.iov = iov;
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qemu_mutex_lock(&client->mutex);
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falcon_proxy_rw(1, client->proxy, client->inode, offset, bytes, iov->iov, iov->niov, falcon_co_generic_bh_cb, &task);
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qemu_mutex_unlock(&client->mutex);
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while (!task.complete)
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{
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qemu_coroutine_yield();
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}
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return task.ret;
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}
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static int coroutine_fn falcon_co_flush(BlockDriverState *bs)
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{
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FalconClient *client = bs->opaque;
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FalconRPC task;
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falcon_co_init_task(bs, &task);
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qemu_mutex_lock(&client->mutex);
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falcon_proxy_sync(client->proxy, falcon_co_generic_bh_cb, &task);
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qemu_mutex_unlock(&client->mutex);
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while (!task.complete)
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{
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qemu_coroutine_yield();
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}
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return task.ret;
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}
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static QemuOptsList falcon_create_opts = {
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.name = "falcon-create-opts",
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.head = QTAILQ_HEAD_INITIALIZER(falcon_create_opts.head),
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.desc = {
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{
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.name = BLOCK_OPT_SIZE,
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.type = QEMU_OPT_SIZE,
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.help = "Virtual disk size"
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},
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{ /* end of list */ }
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}
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};
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static const char *falcon_strong_runtime_opts[] = {
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"image",
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"server.",
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NULL
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};
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static BlockDriver bdrv_falcon = {
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.format_name = "falcon",
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.protocol_name = "falcon",
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.instance_size = sizeof(FalconClient),
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.bdrv_parse_filename = falcon_parse_filename,
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.bdrv_has_zero_init = bdrv_has_zero_init_1,
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.bdrv_has_zero_init_truncate = bdrv_has_zero_init_1,
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.bdrv_get_info = falcon_get_info,
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.bdrv_getlength = falcon_getlength,
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.bdrv_probe_blocksizes = falcon_probe_blocksizes,
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// FIXME: Implement it along with per-inode statistics
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//.bdrv_get_allocated_file_size = falcon_get_allocated_file_size,
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.bdrv_file_open = falcon_file_open,
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.bdrv_close = falcon_close,
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// Option list for the create operation
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.create_opts = &falcon_create_opts,
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// For qmp_blockdev_create(), used by the qemu monitor / QAPI
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// Requires patching QAPI IDL, thus unimplemented
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//.bdrv_co_create = falcon_co_create,
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// For bdrv_create(), used by qemu-img
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.bdrv_co_create_opts = falcon_co_create_opts,
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.bdrv_co_truncate = falcon_co_truncate,
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.bdrv_co_preadv = falcon_co_preadv,
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.bdrv_co_pwritev = falcon_co_pwritev,
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.bdrv_co_flush_to_disk = falcon_co_flush,
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.strong_runtime_opts = falcon_strong_runtime_opts,
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};
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static void falcon_block_init(void)
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{
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bdrv_register(&bdrv_falcon);
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}
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block_init(falcon_block_init);
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