Merge remote-tracking branch 'remotes/ericb/tags/pull-nbd-2017-10-30' into staging

nbd patches for 2017-10-30

Vladimir Sementsov-Ogievskiy (some patches co-authored by Eric Blake):
00/12 nbd minimal structured read

# gpg: Signature made Mon 30 Oct 2017 20:54:54 GMT
# gpg:                using RSA key 0xA7A16B4A2527436A
# gpg: Good signature from "Eric Blake <eblake@redhat.com>"
# gpg:                 aka "Eric Blake (Free Software Programmer) <ebb9@byu.net>"
# gpg:                 aka "[jpeg image of size 6874]"
# Primary key fingerprint: 71C2 CC22 B1C4 6029 27D2  F3AA A7A1 6B4A 2527 436A

* remotes/ericb/tags/pull-nbd-2017-10-30:
  nbd: Minimal structured read for client
  nbd: Move nbd_read() to common header
  nbd/client: prepare nbd_receive_reply for structured reply
  nbd/client: refactor nbd_receive_starttls
  nbd/server: Include human-readable message in structured errors
  nbd: Minimal structured read for server
  nbd/server: Refactor zero-length option check
  nbd/server: Simplify nbd_negotiate_options loop
  nbd/server: Report error for write to read-only export
  nbd: Expose constants and structs for structured read
  nbd: Move nbd_errno_to_system_errno() to public header
  nbd: Include error names in trace messages

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 100 insertions, 6 deletions

diff --git a/include/block/nbd.h b/include/block/nbd.h
index a6df5ce..92d1723 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -57,18 +57,48 @@ struct NBDRequest {
 };
 typedef struct NBDRequest NBDRequest;
 
-struct NBDReply {
-    uint64_t handle;
-    uint32_t error;
-};
-typedef struct NBDReply NBDReply;
-
 typedef struct NBDSimpleReply {
     uint32_t magic;  /* NBD_SIMPLE_REPLY_MAGIC */
     uint32_t error;
     uint64_t handle;
 } QEMU_PACKED NBDSimpleReply;
 
+/* Header of all structured replies */
+typedef struct NBDStructuredReplyChunk {
+    uint32_t magic;  /* NBD_STRUCTURED_REPLY_MAGIC */
+    uint16_t flags;  /* combination of NBD_REPLY_FLAG_* */
+    uint16_t type;   /* NBD_REPLY_TYPE_* */
+    uint64_t handle; /* request handle */
+    uint32_t length; /* length of payload */
+} QEMU_PACKED NBDStructuredReplyChunk;
+
+typedef union NBDReply {
+    NBDSimpleReply simple;
+    NBDStructuredReplyChunk structured;
+    struct {
+        /* @magic and @handle fields have the same offset and size both in
+         * simple reply and structured reply chunk, so let them be accessible
+         * without ".simple." or ".structured." specification
+         */
+        uint32_t magic;
+        uint32_t _skip;
+        uint64_t handle;
+    } QEMU_PACKED;
+} NBDReply;
+
+/* Header of NBD_REPLY_TYPE_OFFSET_DATA, complete NBD_REPLY_TYPE_OFFSET_HOLE */
+typedef struct NBDStructuredRead {
+    NBDStructuredReplyChunk h;
+    uint64_t offset;
+} QEMU_PACKED NBDStructuredRead;
+
+/* Header of all NBD_REPLY_TYPE_ERROR* errors */
+typedef struct NBDStructuredError {
+    NBDStructuredReplyChunk h;
+    uint32_t error;
+    uint16_t message_length;
+} QEMU_PACKED NBDStructuredError;
+
 /* Transmission (export) flags: sent from server to client during handshake,
    but describe what will happen during transmission */
 #define NBD_FLAG_HAS_FLAGS         (1 << 0) /* Flags are there */
@@ -79,6 +109,7 @@ typedef struct NBDSimpleReply {
                                                rotational media */
 #define NBD_FLAG_SEND_TRIM         (1 << 5) /* Send TRIM (discard) */
 #define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* Send WRITE_ZEROES */
+#define NBD_FLAG_SEND_DF           (1 << 7) /* Send DF (Do not Fragment) */
 
 /* New-style handshake (global) flags, sent from server to client, and
    control what will happen during handshake phase. */
@@ -125,6 +156,7 @@ typedef struct NBDSimpleReply {
 /* Request flags, sent from client to server during transmission phase */
 #define NBD_CMD_FLAG_FUA        (1 << 0) /* 'force unit access' during write */
 #define NBD_CMD_FLAG_NO_HOLE    (1 << 1) /* don't punch hole on zero run */
+#define NBD_CMD_FLAG_DF         (1 << 2) /* don't fragment structured read */
 
 /* Supported request types */
 enum {
@@ -149,10 +181,49 @@ enum {
  * aren't overflowing some other buffer. */
 #define NBD_MAX_NAME_SIZE 256
 
+/* Two types of reply structures */
+#define NBD_SIMPLE_REPLY_MAGIC      0x67446698
+#define NBD_STRUCTURED_REPLY_MAGIC  0x668e33ef
+
+/* Structured reply flags */
+#define NBD_REPLY_FLAG_DONE          (1 << 0) /* This reply-chunk is last */
+
+/* Structured reply types */
+#define NBD_REPLY_ERR(value)         ((1 << 15) | (value))
+
+#define NBD_REPLY_TYPE_NONE          0
+#define NBD_REPLY_TYPE_OFFSET_DATA   1
+#define NBD_REPLY_TYPE_OFFSET_HOLE   2
+#define NBD_REPLY_TYPE_ERROR         NBD_REPLY_ERR(1)
+#define NBD_REPLY_TYPE_ERROR_OFFSET  NBD_REPLY_ERR(2)
+
+static inline bool nbd_reply_type_is_error(int type)
+{
+    return type & (1 << 15);
+}
+
+/* NBD errors are based on errno numbers, so there is a 1:1 mapping,
+ * but only a limited set of errno values is specified in the protocol.
+ * Everything else is squashed to EINVAL.
+ */
+#define NBD_SUCCESS    0
+#define NBD_EPERM      1
+#define NBD_EIO        5
+#define NBD_ENOMEM     12
+#define NBD_EINVAL     22
+#define NBD_ENOSPC     28
+#define NBD_EOVERFLOW  75
+#define NBD_ESHUTDOWN  108
+
 /* Details collected by NBD_OPT_EXPORT_NAME and NBD_OPT_GO */
 struct NBDExportInfo {
     /* Set by client before nbd_receive_negotiate() */
     bool request_sizes;
+
+    /* In-out fields, set by client before nbd_receive_negotiate() and
+     * updated by server results during nbd_receive_negotiate() */
+    bool structured_reply;
+
     /* Set by server results during nbd_receive_negotiate() */
     uint64_t size;
     uint16_t flags;
@@ -172,6 +243,7 @@ int nbd_send_request(QIOChannel *ioc, NBDRequest *request);
 int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp);
 int nbd_client(int fd);
 int nbd_disconnect(int fd);
+int nbd_errno_to_system_errno(int err);
 
 typedef struct NBDExport NBDExport;
 typedef struct NBDClient NBDClient;
@@ -202,4 +274,26 @@ void nbd_client_put(NBDClient *client);
 void nbd_server_start(SocketAddress *addr, const char *tls_creds,
                       Error **errp);
 
+
+/* nbd_read
+ * Reads @size bytes from @ioc. Returns 0 on success.
+ */
+static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size,
+                           Error **errp)
+{
+    return qio_channel_read_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
+}
+
+static inline bool nbd_reply_is_simple(NBDReply *reply)
+{
+    return reply->magic == NBD_SIMPLE_REPLY_MAGIC;
+}
+
+static inline bool nbd_reply_is_structured(NBDReply *reply)
+{
+    return reply->magic == NBD_STRUCTURED_REPLY_MAGIC;
+}
+
+const char *nbd_reply_type_lookup(uint16_t type);
+
 #endif