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authorPaolo Bonzini <pbonzini@redhat.com>2012-07-18 14:57:15 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2012-07-24 09:31:53 +0200
commit39a5235cd7f367cce7be7b3f4d258452452e38e3 (patch)
treef0d618f82745259de3144ec4bdcca3f336a453ca /qemu-nbd.c
parentb033cd864042646dd3e17a23c7850c413bc360f4 (diff)
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>
Diffstat (limited to 'qemu-nbd.c')
-rw-r--r--qemu-nbd.c42
1 files changed, 40 insertions, 2 deletions
diff --git a/qemu-nbd.c b/qemu-nbd.c
index 1c32290a8e..1c1cf6a463 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -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;