[Qemu-devel] [PATCH 17/25] nbd: Employ timeouts

[Max Reitz <mreitz@redhat.com>]

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/nbd-client.c  | 35 +++++++++++++++++++++++++++++++----
 include/block/nbd.h |  2 ++
 nbd.c               | 12 ++++++++++--
 3 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/block/nbd-client.c b/block/nbd-client.c
index e1bb919..be6803d 100644
--- a/block/nbd-client.c
+++ b/block/nbd-client.c
@@ -28,6 +28,7 @@
 
 #include "nbd-client.h"
 #include "qemu/sockets.h"
+#include "qemu/timer.h"
 
 #define HANDLE_TO_INDEX(bs, handle) ((handle) ^ ((uint64_t)(intptr_t)bs))
 #define INDEX_TO_HANDLE(bs, index)  ((index)  ^ ((uint64_t)(intptr_t)bs))
@@ -158,15 +159,21 @@ static void nbd_co_receive_reply(NbdClientSession *s,
 
     /* Wait until we're woken up by the read handler.  TODO: perhaps
      * peek at the next reply and avoid yielding if it's ours?  */
-    qemu_coroutine_yield();
+    if (co_yield_timeout(QEMU_CLOCK_REALTIME, NBD_TIMEOUT)) {
+        reply->error = ETIMEDOUT;
+        return;
+    }
+
     *reply = s->reply;
     if (reply->handle != request->handle) {
         reply->error = EIO;
     } else {
         if (qiov && reply->error == 0) {
-            ret = qemu_co_recvv(s->sock, qiov->iov, qiov->niov,
-                                offset, request->len);
-            if (ret != request->len) {
+            ret = qemu_co_recvv_timeout(s->sock, qiov->iov, qiov->niov,
+                                        offset, request->len, NBD_TIMEOUT);
+            if (ret < 0) {
+                reply->error = -ret;
+            } else if (ret != request->len) {
                 reply->error = EIO;
             }
         }
@@ -220,6 +227,11 @@ static int nbd_co_readv_1(BlockDriverState *bs, int64_t sector_num,
         nbd_co_receive_reply(client, &request, &reply, qiov, offset);
     }
     nbd_coroutine_end(client, &request);
+
+    if (reply.error == ETIMEDOUT) {
+        nbd_teardown_connection(bs);
+    }
+
     return -reply.error;
 
 }
@@ -249,6 +261,11 @@ static int nbd_co_writev_1(BlockDriverState *bs, int64_t sector_num,
         nbd_co_receive_reply(client, &request, &reply, NULL, 0);
     }
     nbd_coroutine_end(client, &request);
+
+    if (reply.error == ETIMEDOUT) {
+        nbd_teardown_connection(bs);
+    }
+
     return -reply.error;
 }
 
@@ -316,6 +333,11 @@ int nbd_client_co_flush(BlockDriverState *bs)
         nbd_co_receive_reply(client, &request, &reply, NULL, 0);
     }
     nbd_coroutine_end(client, &request);
+
+    if (reply.error == ETIMEDOUT) {
+        nbd_teardown_connection(bs);
+    }
+
     return -reply.error;
 }
 
@@ -341,6 +363,11 @@ int nbd_client_co_discard(BlockDriverState *bs, int64_t sector_num,
         nbd_co_receive_reply(client, &request, &reply, NULL, 0);
     }
     nbd_coroutine_end(client, &request);
+
+    if (reply.error == ETIMEDOUT) {
+        nbd_teardown_connection(bs);
+    }
+
     return -reply.error;
 
 }
diff --git a/include/block/nbd.h b/include/block/nbd.h
index 65f409d..5e31986 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -73,6 +73,8 @@ enum {
 /* Maximum size of a single READ/WRITE data buffer */
 #define NBD_MAX_BUFFER_SIZE (32 * 1024 * 1024)
 
+#define NBD_TIMEOUT (INT64_C(10) * 1000 * 1000 * 1000) /* ns */
+
 ssize_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read);
 int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
                           off_t *size, Error **errp);
diff --git a/nbd.c b/nbd.c
index 5764fd1..a05fd02 100644
--- a/nbd.c
+++ b/nbd.c
@@ -140,12 +140,13 @@ static void nbd_update_can_read(NBDClient *client);
 
 ssize_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read)
 {
+    int64_t deadline = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + NBD_TIMEOUT;
     size_t offset = 0;
     int err;
 
     if (qemu_in_coroutine()) {
         if (do_read) {
-            return qemu_co_recv(fd, buffer, size);
+            return qemu_co_recv_timeout(fd, buffer, size, NBD_TIMEOUT);
         } else {
             return qemu_co_send(fd, buffer, size);
         }
@@ -154,6 +155,10 @@ ssize_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read)
     while (offset < size) {
         ssize_t len;
 
+        if (do_read && qemu_clock_get_ns(QEMU_CLOCK_REALTIME) >= deadline) {
+            return -ETIMEDOUT;
+        }
+
         if (do_read) {
             len = qemu_recv(fd, buffer + offset, size - offset, 0);
         } else {
@@ -178,6 +183,7 @@ ssize_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read)
         }
 
         offset += len;
+        deadline = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + NBD_TIMEOUT;
     }
 
     return offset;
@@ -1208,7 +1214,9 @@ static ssize_t nbd_co_receive_request(NBDRequest *req, struct nbd_request *reque
     if (command == NBD_CMD_WRITE) {
         TRACE("Reading %u byte(s)", request->len);
 
-        if (qemu_co_recv(csock, req->data, request->len) != request->len) {
+        if (qemu_co_recv_timeout(csock, req->data, request->len, NBD_TIMEOUT)
+            != request->len)
+        {
             LOG("reading from socket failed");
             rc = -EIO;
             goto out;
-- 
2.1.0