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qemu-nbd: add --cache and --aio options 

Add two options to tune the I/O implementation of qemu-nbd, matching
the possibilities given by the QEMU -drive option.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
master
Paolo Bonzini 2012-07-18 14:57:15 +02:00
parent b033cd8640
commit 39a5235cd7
1 changed files with 40 additions and 2 deletions
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42
qemu-nbd.c
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@ -33,7 +33,9 @@
#include <libgen.h>
#include <pthread.h>
#define SOCKET_PATH "/var/lock/qemu-nbd-%s"
#define SOCKET_PATH "/var/lock/qemu-nbd-%s"
#define QEMU_NBD_OPT_CACHE 1
#define QEMU_NBD_OPT_AIO 2
static NBDExport *exp;
static int verbose;
@ -77,6 +79,10 @@ static void usage(const char *name)
" -r, --read-only export read-only\n"
" -s, --snapshot use snapshot file\n"
" -n, --nocache disable host cache\n"
" --cache=MODE set cache mode (none, writeback, ...)\n"
#ifdef CONFIG_LINUX_AIO
" --aio=MODE set AIO mode (native or threads)\n"
#endif
"\n"
"Report bugs to <qemu-devel@nongnu.org>\n"
, name, NBD_DEFAULT_PORT, "DEVICE");
@ -306,6 +312,10 @@ int main(int argc, char **argv)
{ "disconnect", 0, NULL, 'd' },
{ "snapshot", 0, NULL, 's' },
{ "nocache", 0, NULL, 'n' },
{ "cache", 1, NULL, QEMU_NBD_OPT_CACHE },
#ifdef CONFIG_LINUX_AIO
{ "aio", 1, NULL, QEMU_NBD_OPT_AIO },
#endif
{ "shared", 1, NULL, 'e' },
{ "persistent", 0, NULL, 't' },
{ "verbose", 0, NULL, 'v' },
@ -320,6 +330,10 @@ int main(int argc, char **argv)
int ret;
int fd;
int persistent = 0;
bool seen_cache = false;
#ifdef CONFIG_LINUX_AIO
bool seen_aio = false;
#endif
pthread_t client_thread;
/* The client thread uses SIGTERM to interrupt the server. A signal
@ -336,8 +350,32 @@ int main(int argc, char **argv)
flags |= BDRV_O_SNAPSHOT;
break;
case 'n':
flags |= BDRV_O_NOCACHE | BDRV_O_CACHE_WB;
optarg = (char *) "none";
/* fallthrough */
case QEMU_NBD_OPT_CACHE:
if (seen_cache) {
errx(EXIT_FAILURE, "-n and --cache can only be specified once");
}
seen_cache = true;
if (bdrv_parse_cache_flags(optarg, &flags) == -1) {
errx(EXIT_FAILURE, "Invalid cache mode `%s'", optarg);
}
break;
#ifdef CONFIG_LINUX_AIO
case QEMU_NBD_OPT_AIO:
if (seen_aio) {
errx(EXIT_FAILURE, "--aio can only be specified once");
}
seen_aio = true;
if (!strcmp(optarg, "native")) {
flags |= BDRV_O_NATIVE_AIO;
} else if (!strcmp(optarg, "threads")) {
/* this is the default */
} else {
errx(EXIT_FAILURE, "invalid aio mode `%s'", optarg);
}
break;
#endif
case 'b':
bindto = optarg;
break;