diff --git a/buse.c b/buse.c
index 54415aa..bec09ea 100644
--- a/buse.c
+++ b/buse.c
@@ -18,150 +18,159 @@
  */
 #ifdef WORDS_BIGENDIAN
 u_int64_t ntohll(u_int64_t a) {
-	return a;
+  return a;
 }
 #else
 u_int64_t ntohll(u_int64_t a) {
-	u_int32_t lo = a & 0xffffffff;
-	u_int32_t hi = a >> 32U;
-	lo = ntohl(lo);
-	hi = ntohl(hi);
-	return ((u_int64_t) lo) << 32U | hi;
+  u_int32_t lo = a & 0xffffffff;
+  u_int32_t hi = a >> 32U;
+  lo = ntohl(lo);
+  hi = ntohl(hi);
+  return ((u_int64_t) lo) << 32U | hi;
 }
 #endif
 #define htonll ntohll
 
-static int read_all(int fd, void *buf, size_t count)
+static int read_all(int fd, char* buf, size_t count)
 {
-    int bytes_read;
+  int bytes_read;
 
-    while (count > 0) {
-        bytes_read = read(fd, buf, count);
-        assert(bytes_read > 0);
-        buf = (char *)buf + bytes_read;
-        count -= bytes_read;
-    }
-    assert(count == 0);
+  while (count > 0) {
+    bytes_read = read(fd, buf, count);
+    assert(bytes_read > 0);
+    buf += bytes_read;
+    count -= bytes_read;
+  }
+  assert(count == 0);
 
-    return 0;
+  return 0;
 }
 
-static int write_all(int fd, const void *buf, size_t count)
+static int write_all(int fd, char* buf, size_t count)
 {
-    int bytes_written;
+  int bytes_written;
 
-    while (count > 0) {
-        bytes_written = write(fd, buf, count);
-        assert(bytes_written > 0);
-        buf = (char *)buf + bytes_written;
-        count -= bytes_written;
-    }
-    assert(count == 0);
+  while (count > 0) {
+    bytes_written = write(fd, buf, count);
+    assert(bytes_written > 0);
+    buf += bytes_written;
+    count -= bytes_written;
+  }
+  assert(count == 0);
 
-    return 0;
+  return 0;
 }
 
 int buse_main(int argc, char *argv[], const struct buse_operations *aop, void *userdata)
 {
-    int sp[2];
-    int nbd, sk, err, tmp_fd;
-    u_int64_t from;
-    u_int32_t len, bytes_read;
-    char *dev_file;
-    struct nbd_request request;
-    struct nbd_reply reply;
-    void *chunk;
+  int sp[2];
+  int nbd, sk, err, tmp_fd;
+  u_int64_t from;
+  u_int32_t len, bytes_read;
+  char *dev_file;
+  struct nbd_request request;
+  struct nbd_reply reply;
+  void *chunk;
 
-    (void) userdata;
+  (void) userdata;
 
-    assert(argc == 2);
-    dev_file = argv[1];
+  assert(argc == 2);
+  dev_file = argv[1];
 
-    assert(!socketpair(AF_UNIX, SOCK_STREAM, 0, sp));
+  assert(!socketpair(AF_UNIX, SOCK_STREAM, 0, sp));
 
-    nbd = open(dev_file, O_RDWR);
-    assert(nbd != -1);
+  nbd = open(dev_file, O_RDWR);
+  assert(nbd != -1);
 
-    assert(ioctl(nbd, NBD_SET_SIZE, aop->size) != -1);
-    assert(ioctl(nbd, NBD_CLEAR_SOCK) != -1);
+  assert(ioctl(nbd, NBD_SET_SIZE, aop->size) != -1);
+  assert(ioctl(nbd, NBD_CLEAR_SOCK) != -1);
 
-    if (!fork()) {
-        /* The child needs to continue setting things up. */
-        close(sp[0]);
-        sk = sp[1];
+  if (!fork()) {
+    /* The child needs to continue setting things up. */
+    close(sp[0]);
+    sk = sp[1];
 
-        assert(ioctl(nbd, NBD_SET_SOCK, sk) != -1);
-	assert(ioctl(nbd, NBD_SET_FLAGS, NBD_FLAG_SEND_TRIM) != -1);
-        err = ioctl(nbd, NBD_DO_IT);
-        fprintf(stderr, "nbd device terminated with code %d\n", err);
-        if (err == -1)
-            fprintf(stderr, "%s\n", strerror(errno));
-
-        assert(ioctl(nbd, NBD_CLEAR_QUE) != -1);
-        assert(ioctl(nbd, NBD_CLEAR_SOCK) != -1);
-
-        exit(0);
+    if(ioctl(nbd, NBD_SET_SOCK, sk) == -1){
+      fprintf(stderr, "ioctl(nbd, NBD_SET_SOCK, sk) failed.[%s]\n", strerror(errno));
+    }
+    else if(ioctl(nbd, NBD_SET_FLAGS, NBD_FLAG_SEND_TRIM) == -1){
+      fprintf(stderr, "ioctl(nbd, NBD_SET_FLAGS, NBD_FLAG_SEND_TRIM) failed.[%s]\n", strerror(errno));
+    }
+    else{
+      err = ioctl(nbd, NBD_DO_IT);
+      fprintf(stderr, "nbd device terminated with code %d\n", err);
+      if (err == -1)
+	fprintf(stderr, "%s\n", strerror(errno));
     }
 
-    /* The parent opens the device file at least once, to make sure the
-     * partition table is updated. Then it closes it and starts serving up
-     * requests. */
+    ioctl(nbd, NBD_CLEAR_QUE);
+    ioctl(nbd, NBD_CLEAR_SOCK);
 
-    tmp_fd = open(dev_file, O_RDONLY);
-    assert(tmp_fd != -1);
-    close(tmp_fd);
+    exit(0);
+  }
 
-    close(sp[1]);
-    sk = sp[0];
+  /* The parent opens the device file at least once, to make sure the
+   * partition table is updated. Then it closes it and starts serving up
+   * requests. */
 
-    reply.magic = htonl(NBD_REPLY_MAGIC);
-    reply.error = htonl(0);
+  tmp_fd = open(dev_file, O_RDONLY);
+  assert(tmp_fd != -1);
+  close(tmp_fd);
 
-    while (1) {
-        bytes_read = read(sk, &request, sizeof(request));
-        assert(bytes_read == sizeof(request));
-        memcpy(reply.handle, request.handle, sizeof(reply.handle));
+  close(sp[1]);
+  sk = sp[0];
 
-        len = ntohl(request.len);
-        from = ntohll(request.from);
-        assert(request.magic == htonl(NBD_REQUEST_MAGIC));
+  reply.magic = htonl(NBD_REPLY_MAGIC);
+  reply.error = htonl(0);
 
-        switch(ntohl(request.type)) {
-            /* I may at some point need to deal with the the fact that the
-             * official nbd server has a maximum buffer size, and divides up
-             * oversized requests into multiple pieces. This applies to reads
-             * and writes.
-             */
-            case NBD_CMD_READ:
-                /* fprintf(stderr, "Request for read of size %d\n", len); */
-                chunk = malloc(len + sizeof(struct nbd_reply));
-                aop->read((char *)chunk + sizeof(struct nbd_reply), len, from);
-                memcpy(chunk, &reply, sizeof(struct nbd_reply));
-                write_all(sk, chunk, len + sizeof(struct nbd_reply));
-                free(chunk);
-                break;
-            case NBD_CMD_WRITE:
-                /* fprintf(stderr, "Request for write of size %d\n", len); */
-                chunk = malloc(len);
-                read_all(sk, chunk, len);
-                aop->write(chunk, len, from);
-                free(chunk);
-                write_all(sk, &reply, sizeof(struct nbd_reply));
-                break;
-            case NBD_CMD_DISC:
-                /* Handle a disconnect request. */
-                aop->disc();
-                return 0;
-            case NBD_CMD_FLUSH:
-                aop->flush();
-                break;
-            case NBD_CMD_TRIM:
-                aop->trim(from, len);
-                break;
-            default:
-                assert(0);
-        }
+  while ((bytes_read = read(sk, &request, sizeof(request))) > 0) {
+    assert(bytes_read == sizeof(request));
+    memcpy(reply.handle, request.handle, sizeof(reply.handle));
+
+    len = ntohl(request.len);
+    from = ntohll(request.from);
+    assert(request.magic == htonl(NBD_REQUEST_MAGIC));
+
+    switch(ntohl(request.type)) {
+      /* I may at some point need to deal with the the fact that the
+       * official nbd server has a maximum buffer size, and divides up
+       * oversized requests into multiple pieces. This applies to reads
+       * and writes.
+       */
+    case NBD_CMD_READ:
+      /* fprintf(stderr, "Request for read of size %d\n", len); */
+      chunk = malloc(len + sizeof(struct nbd_reply));
+      reply.error = aop->read((char *)chunk + sizeof(struct nbd_reply), len, from);
+      write_all(sk, (char*)&reply, sizeof(struct nbd_reply));
+      if(reply.error == 0)
+	write_all(sk, (char*)chunk, len);
+      free(chunk);
+      break;
+    case NBD_CMD_WRITE:
+      /* fprintf(stderr, "Request for write of size %d\n", len); */
+      chunk = malloc(len);
+      read_all(sk, chunk, len);
+      reply.error = aop->write(chunk, len, from);
+      free(chunk);
+      write_all(sk, (char*)&reply, sizeof(struct nbd_reply));
+      break;
+    case NBD_CMD_DISC:
+      /* Handle a disconnect request. */
+      aop->disc();
+      return 0;
+    case NBD_CMD_FLUSH:
+      reply.error = aop->flush();
+      write_all(sk, (char*)&reply, sizeof(struct nbd_reply));
+      break;
+    case NBD_CMD_TRIM:
+      reply.error = aop->trim(from, len);
+      write_all(sk, (char*)&reply, sizeof(struct nbd_reply));
+      break;
+    default:
+      assert(0);
     }
-
-    return 0;
+  }
+  if (bytes_read == -1)
+    fprintf(stderr, "%s\n", strerror(errno));
+  return 0;
 }
diff --git a/buse.h b/buse.h
index 8b0d57d..943da9e 100644
--- a/buse.h
+++ b/buse.h
@@ -63,7 +63,7 @@ struct nbd_reply {
 struct buse_operations {
     int (*read)(void *buf, u_int32_t len, u_int64_t offset);
     int (*write)(const void *buf, u_int32_t len, u_int64_t offset);
-    int (*disc)();
+    void (*disc)();
     int (*flush)();
     int (*trim)(u_int64_t from, u_int32_t len);
 
diff --git a/busexmp.c b/busexmp.c
index 93dd76a..76991c3 100644
--- a/busexmp.c
+++ b/busexmp.c
@@ -20,9 +20,20 @@ static int xmp_write(const void *buf, u_int32_t len, u_int64_t offset)
   return 0;
 }
 
-static int xmp_disc()
+static void xmp_disc()
 {
   fprintf(stderr, "Received a disconnect request.\n");
+}
+
+static int xmp_flush()
+{
+  fprintf(stderr, "Received a flush request.\n");
+  return 0;
+}
+
+static int xmp_trim(u_int64_t from, u_int32_t len)
+{
+  fprintf(stderr, "T %lu %u\n", from, len);
   return 0;
 }
 
@@ -41,8 +52,8 @@ static struct buse_operations aop = {
   .read = xmp_read,
   .write = xmp_write,
   .disc = xmp_disc,
-  .trim = xmp_trim,
   .flush = xmp_flush,
+  .trim = xmp_trim,
   .size = 128 * 1024 * 1024,
 };