[Qemu-devel] [PATCH 18/26] qemu-nbd: introduce NBDExport

[Paolo Bonzini <pbonzini@redhat.com>]

Wrap the common parameters of nbd_trip and nbd_negotiate in a
single opaque struct.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 nbd.c      |   64 +++++++++++++++++++++++++++++++++++++++++++++---------------
 nbd.h      |   11 +++++++--
 qemu-nbd.c |   15 ++++---------
 3 files changed, 61 insertions(+), 29 deletions(-)

diff --git a/nbd.c b/nbd.c
index 964a732..8d2a3bc 100644
--- a/nbd.c
+++ b/nbd.c
@@ -18,6 +18,7 @@
 
 #include "nbd.h"
 #include "block.h"
+#include "block_int.h"
 
 #include <errno.h>
 #include <string.h>
@@ -186,7 +187,7 @@ int unix_socket_outgoing(const char *path)
                   Request (type == 2)
 */
 
-int nbd_negotiate(int csock, off_t size, uint32_t flags)
+static int nbd_send_negotiate(int csock, off_t size, uint32_t flags)
 {
     char buf[8 + 8 + 8 + 128];
 
@@ -583,6 +584,33 @@ static int nbd_send_reply(int csock, struct nbd_reply *reply)
     return 0;
 }
 
+struct NBDExport {
+    BlockDriverState *bs;
+    off_t dev_offset;
+    off_t size;
+    uint8_t *data;
+    uint32_t nbdflags;
+};
+
+NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset,
+                          off_t size, uint32_t nbdflags)
+{
+    NBDExport *exp = g_malloc0(sizeof(NBDExport));
+    exp->bs = bs;
+    exp->dev_offset = dev_offset;
+    exp->nbdflags = nbdflags;
+    exp->size = size == -1 ? exp->bs->total_sectors * 512 : size;
+    exp->data = qemu_blockalign(exp->bs, NBD_BUFFER_SIZE);
+    return exp;
+}
+
+void nbd_export_close(NBDExport *exp)
+{
+    qemu_vfree(exp->data);
+    bdrv_close(exp->bs);
+    g_free(exp);
+}
+
 static int nbd_do_send_reply(int csock, struct nbd_reply *reply,
                              uint8_t *data, int len)
 {
@@ -652,9 +680,7 @@ out:
     return rc;
 }
 
-int nbd_trip(BlockDriverState *bs, int csock, off_t size,
-             uint64_t dev_offset, uint32_t nbdflags,
-             uint8_t *data)
+int nbd_trip(NBDExport *exp, int csock)
 {
     struct nbd_request request;
     struct nbd_reply reply;
@@ -662,7 +688,7 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size,
 
     TRACE("Reading request.");
 
-    ret = nbd_do_receive_request(csock, &request, data);
+    ret = nbd_do_receive_request(csock, &request, exp->data);
     if (ret == -EIO) {
         return -1;
     }
@@ -675,10 +701,11 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size,
         goto error_reply;
     }
 
-    if ((request.from + request.len) > size) {
+    if ((request.from + request.len) > exp->size) {
             LOG("From: %" PRIu64 ", Len: %u, Size: %" PRIu64
             ", Offset: %" PRIu64 "\n",
-                    request.from, request.len, (uint64_t)size, dev_offset);
+                    request.from, request.len,
+                    (uint64_t)exp->size, exp->dev_offset);
         LOG("requested operation past EOF--bad client?");
         goto invalid_request;
     }
@@ -687,8 +714,8 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size,
     case NBD_CMD_READ:
         TRACE("Request type is READ");
 
-        ret = bdrv_read(bs, (request.from + dev_offset) / 512,
-                        data, request.len / 512);
+        ret = bdrv_read(exp->bs, (request.from + exp->dev_offset) / 512,
+                        exp->data, request.len / 512);
         if (ret < 0) {
             LOG("reading from file failed");
             reply.error = -ret;
@@ -696,13 +723,13 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size,
         }
 
         TRACE("Read %u byte(s)", request.len);
-        if (nbd_do_send_reply(csock, &reply, data, request.len) < 0)
+        if (nbd_do_send_reply(csock, &reply, exp->data, request.len) < 0)
             return -1;
         break;
     case NBD_CMD_WRITE:
         TRACE("Request type is WRITE");
 
-        if (nbdflags & NBD_FLAG_READ_ONLY) {
+        if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
             TRACE("Server is read-only, return error");
             reply.error = EROFS;
             goto error_reply;
@@ -710,8 +737,8 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size,
 
         TRACE("Writing to device");
 
-        ret = bdrv_write(bs, (request.from + dev_offset) / 512,
-                         data, request.len / 512);
+        ret = bdrv_write(exp->bs, (request.from + exp->dev_offset) / 512,
+                         exp->data, request.len / 512);
         if (ret < 0) {
             LOG("writing to file failed");
             reply.error = -ret;
@@ -719,7 +746,7 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size,
         }
 
         if (request.type & NBD_CMD_FLAG_FUA) {
-            ret = bdrv_flush(bs);
+            ret = bdrv_flush(exp->bs);
             if (ret < 0) {
                 LOG("flush failed");
                 reply.error = -ret;
@@ -737,7 +764,7 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size,
     case NBD_CMD_FLUSH:
         TRACE("Request type is FLUSH");
 
-        ret = bdrv_flush(bs);
+        ret = bdrv_flush(exp->bs);
         if (ret < 0) {
             LOG("flush failed");
             reply.error = -ret;
@@ -748,7 +775,7 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size,
         break;
     case NBD_CMD_TRIM:
         TRACE("Request type is TRIM");
-        ret = bdrv_discard(bs, (request.from + dev_offset) / 512,
+        ret = bdrv_discard(exp->bs, (request.from + exp->dev_offset) / 512,
                            request.len / 512);
         if (ret < 0) {
             LOG("discard failed");
@@ -771,3 +798,8 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size,
 
     return 0;
 }
+
+int nbd_negotiate(NBDExport *exp, int csock)
+{
+    return nbd_send_negotiate(csock, exp->size, exp->nbdflags);
+}
diff --git a/nbd.h b/nbd.h
index dbc4c0d..c77c2fd 100644
--- a/nbd.h
+++ b/nbd.h
@@ -67,15 +67,20 @@ int tcp_socket_incoming_spec(const char *address_and_port);
 int unix_socket_outgoing(const char *path);
 int unix_socket_incoming(const char *path);
 
-int nbd_negotiate(int csock, off_t size, uint32_t flags);
 int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
                           off_t *size, size_t *blocksize);
 int nbd_init(int fd, int csock, uint32_t flags, off_t size, size_t blocksize);
 int nbd_send_request(int csock, struct nbd_request *request);
 int nbd_receive_reply(int csock, struct nbd_reply *reply);
-int nbd_trip(BlockDriverState *bs, int csock, off_t size, uint64_t dev_offset,
-             uint32_t nbdflags, uint8_t *data);
 int nbd_client(int fd);
 int nbd_disconnect(int fd);
 
+typedef struct NBDExport NBDExport;
+
+NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset,
+                          off_t size, uint32_t nbdflags);
+void nbd_export_close(NBDExport *exp);
+int nbd_negotiate(NBDExport *exp, int csock);
+int nbd_trip(NBDExport *exp, int csock);
+
 #endif
diff --git a/qemu-nbd.c b/qemu-nbd.c
index d662268..d5ac75e 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -36,6 +36,7 @@
 #define SOCKET_PATH    "/var/lock/qemu-nbd-%s"
 
 static int sigterm_wfd;
+static NBDExport *exp;
 static int verbose;
 static char *device;
 static char *srcpath;
@@ -280,7 +281,6 @@ int main(int argc, char **argv)
     int partition = -1;
     int ret;
     int shared = 1;
-    uint8_t *data;
     fd_set fds;
     int *sharing_fds;
     int fd;
@@ -489,6 +489,7 @@ int main(int argc, char **argv)
         err(EXIT_FAILURE, "Could not find partition %d", partition);
     }
 
+    exp = nbd_export_new(bs, dev_offset, fd_size, nbdflags);
     sharing_fds = g_malloc((shared + 1) * sizeof(int));
 
     if (sockpath) {
@@ -516,11 +517,6 @@ int main(int argc, char **argv)
     max_fd = sharing_fds[0];
     nb_fds++;
 
-    data = qemu_blockalign(bs, NBD_BUFFER_SIZE);
-    if (data == NULL) {
-        errx(EXIT_FAILURE, "Cannot allocate data buffer");
-    }
-
     do {
         FD_ZERO(&fds);
         FD_SET(sigterm_fd[0], &fds);
@@ -538,8 +534,7 @@ int main(int argc, char **argv)
             ret--;
         for (i = 1; i < nb_fds && ret; i++) {
             if (FD_ISSET(sharing_fds[i], &fds)) {
-                if (nbd_trip(bs, sharing_fds[i], fd_size, dev_offset,
-                             nbdflags, data) != 0) {
+                if (nbd_trip(exp, sharing_fds[i]) != 0) {
                     close(sharing_fds[i]);
                     nb_fds--;
                     sharing_fds[i] = sharing_fds[nb_fds];
@@ -555,7 +550,7 @@ int main(int argc, char **argv)
                                              (struct sockaddr *)&addr,
                                              &addr_len);
                 if (sharing_fds[nb_fds] != -1 &&
-                    nbd_negotiate(sharing_fds[nb_fds], fd_size, nbdflags) != -1) {
+                    nbd_negotiate(exp, sharing_fds[nb_fds]) != -1) {
                         if (sharing_fds[nb_fds] > max_fd)
                             max_fd = sharing_fds[nb_fds];
                         nb_fds++;
@@ -563,9 +558,9 @@ int main(int argc, char **argv)
             }
         }
     } while (persistent || nb_fds > 1);
-    qemu_vfree(data);
 
     close(sharing_fds[0]);
+    nbd_export_close(exp);
     g_free(sharing_fds);
     if (sockpath) {
         unlink(sockpath);
-- 
1.7.7.1