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authorStefan Hajnoczi <stefanha@redhat.com>2013-05-02 14:23:08 +0200
committerStefan Hajnoczi <stefanha@redhat.com>2013-05-03 13:05:49 +0200
commit2d8214885942becb8f4371a66d6f8c9a9580108a (patch)
tree64ed61dd1bc57a8a0e6f7481f84934c90bd9c3f1
parente1adb27a83f19799c454cead7bf930a0b3f2bb28 (diff)
downloadqemu-arm-2d8214885942becb8f4371a66d6f8c9a9580108a.tar.gz
nbd: support large NBD requests
The Linux nbd driver recently increased the maximum supported request size up to 32 MB: commit 078be02b80359a541928c899c2631f39628f56df Author: Michal Belczyk <belczyk@bsd.krakow.pl> Date: Tue Apr 30 15:28:28 2013 -0700 nbd: increase default and max request sizes Raise the default max request size for nbd to 128KB (from 127KB) to get it 4KB aligned. This patch also allows the max request size to be increased (via /sys/block/nbd<x>/queue/max_sectors_kb) to 32MB. QEMU's 1 MB buffers are too small to handle these requests. This patch allocates data buffers dynamically and allows up to 32 MB per request. Reported-by: Nick Thomas <nick@bytemark.co.uk> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-rw-r--r--include/block/nbd.h3
-rw-r--r--nbd.c17
2 files changed, 13 insertions, 7 deletions
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 0903d7a603..c90f5e4d9e 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -58,7 +58,8 @@ enum {
#define NBD_DEFAULT_PORT 10809
-#define NBD_BUFFER_SIZE (1024*1024)
+/* Maximum size of a single READ/WRITE data buffer */
+#define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024)
ssize_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read);
int tcp_socket_incoming(const char *address, uint16_t port);
diff --git a/nbd.c b/nbd.c
index 761f4ec826..2606403a41 100644
--- a/nbd.c
+++ b/nbd.c
@@ -844,13 +844,11 @@ void nbd_client_close(NBDClient *client)
static NBDRequest *nbd_request_get(NBDClient *client)
{
NBDRequest *req;
- NBDExport *exp = client->exp;
assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
client->nb_requests++;
req = g_slice_new0(NBDRequest);
- req->data = qemu_blockalign(exp->bs, NBD_BUFFER_SIZE);
nbd_client_get(client);
req->client = client;
return req;
@@ -860,7 +858,9 @@ static void nbd_request_put(NBDRequest *req)
{
NBDClient *client = req->client;
- qemu_vfree(req->data);
+ if (req->data) {
+ qemu_vfree(req->data);
+ }
g_slice_free(NBDRequest, req);
if (client->nb_requests-- == MAX_NBD_REQUESTS) {
@@ -1007,6 +1007,7 @@ static ssize_t nbd_co_receive_request(NBDRequest *req, struct nbd_request *reque
{
NBDClient *client = req->client;
int csock = client->sock;
+ uint32_t command;
ssize_t rc;
client->recv_coroutine = qemu_coroutine_self();
@@ -1018,9 +1019,9 @@ static ssize_t nbd_co_receive_request(NBDRequest *req, struct nbd_request *reque
goto out;
}
- if (request->len > NBD_BUFFER_SIZE) {
+ if (request->len > NBD_MAX_BUFFER_SIZE) {
LOG("len (%u) is larger than max len (%u)",
- request->len, NBD_BUFFER_SIZE);
+ request->len, NBD_MAX_BUFFER_SIZE);
rc = -EINVAL;
goto out;
}
@@ -1034,7 +1035,11 @@ static ssize_t nbd_co_receive_request(NBDRequest *req, struct nbd_request *reque
TRACE("Decoding type");
- if ((request->type & NBD_CMD_MASK_COMMAND) == NBD_CMD_WRITE) {
+ command = request->type & NBD_CMD_MASK_COMMAND;
+ if (command == NBD_CMD_READ || command == NBD_CMD_WRITE) {
+ req->data = qemu_blockalign(client->exp->bs, request->len);
+ }
+ if (command == NBD_CMD_WRITE) {
TRACE("Reading %u byte(s)", request->len);
if (qemu_co_recv(csock, req->data, request->len) != request->len) {