Merge remote-tracking branch 'remotes/ericb/tags/pull-nbd-2019-09-05-…

…v2' into staging

nbd patches for 2019-09-05

- Advertise NBD_FLAG_CAN_MULTI_CONN on readonly images
- Tolerate larger set of server error responses during handshake
- More precision on handling fallocate() failures due to alignment
- Better documentation of NBD connection URIs
- Implement new extension NBD_CMD_FLAG_FAST_ZERO to benefit qemu-img convert

# gpg: Signature made Thu 05 Sep 2019 22:08:17 BST
# gpg:                using RSA key 71C2CC22B1C4602927D2F3AAA7A16B4A2527436A
# gpg: Good signature from "Eric Blake <eblake@redhat.com>" [full]
# gpg:                 aka "Eric Blake (Free Software Programmer) <ebb9@byu.net>" [full]
# gpg:                 aka "[jpeg image of size 6874]" [full]
# Primary key fingerprint: 71C2 CC22 B1C4 6029 27D2  F3AA A7A1 6B4A 2527 436A

* remotes/ericb/tags/pull-nbd-2019-09-05-v2:
  nbd: Implement server use of NBD FAST_ZERO
  nbd: Implement client use of NBD FAST_ZERO
  nbd: Prepare for NBD_CMD_FLAG_FAST_ZERO
  nbd: Improve per-export flag handling in server
  docs: Update preferred NBD device syntax
  block: workaround for unaligned byte range in fallocate()
  nbd: Tolerate more errors to structured reply request
  nbd: Use g_autofree in a few places
  nbd: Advertise multi-conn for shared read-only connections

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

block/file-posix.c

@@ -1588,6 +1588,13 @@ static int handle_aiocb_write_zeroes(void *opaque)
     if (s->has_write_zeroes) {
         int ret = do_fallocate(s->fd, FALLOC_FL_ZERO_RANGE,
                                aiocb->aio_offset, aiocb->aio_nbytes);
+        if (ret == -EINVAL) {
+            /*
+             * Allow falling back to pwrite for file systems that
+             * do not support fallocate() for an unaligned byte range.
+             */
+            return -ENOTSUP;
+        }
         if (ret == 0 || ret != -ENOTSUP) {
             return ret;
         }

block/io.c

@@ -1746,7 +1746,7 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
             assert(!bs->supported_zero_flags);
         }
 
-        if (ret < 0 && !(flags & BDRV_REQ_NO_FALLBACK)) {
+        if (ret == -ENOTSUP && !(flags & BDRV_REQ_NO_FALLBACK)) {
             /* Fall back to bounce buffer if write zeroes is unsupported */
             BdrvRequestFlags write_flags = flags & ~BDRV_REQ_ZERO_WRITE;
 

block/nbd.c

@@ -1044,6 +1044,10 @@ static int nbd_client_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
     if (!(flags & BDRV_REQ_MAY_UNMAP)) {
         request.flags |= NBD_CMD_FLAG_NO_HOLE;
     }
+    if (flags & BDRV_REQ_NO_FALLBACK) {
+        assert(s->info.flags & NBD_FLAG_SEND_FAST_ZERO);
+        request.flags |= NBD_CMD_FLAG_FAST_ZERO;
+    }
 
     if (!bytes) {
         return 0;
@@ -1239,6 +1243,9 @@ static int nbd_client_connect(BlockDriverState *bs, Error **errp)
     }
     if (s->info.flags & NBD_FLAG_SEND_WRITE_ZEROES) {
         bs->supported_zero_flags |= BDRV_REQ_MAY_UNMAP;
+        if (s->info.flags & NBD_FLAG_SEND_FAST_ZERO) {
+            bs->supported_zero_flags |= BDRV_REQ_NO_FALLBACK;
+        }
     }
 
     s->sioc = sioc;
@@ -1374,7 +1381,7 @@ static bool nbd_has_filename_options_conflict(QDict *options, Error **errp)
 static void nbd_parse_filename(const char *filename, QDict *options,
                                Error **errp)
 {
-    char *file;
+    g_autofree char *file = NULL;
     char *export_name;
     const char *host_spec;
     const char *unixpath;
@@ -1396,7 +1403,7 @@ static void nbd_parse_filename(const char *filename, QDict *options,
     export_name = strstr(file, EN_OPTSTR);
     if (export_name) {
         if (export_name[strlen(EN_OPTSTR)] == 0) {
-            goto out;
+            return;
         }
         export_name[0] = 0; /* truncate 'file' */
         export_name += strlen(EN_OPTSTR);
@@ -1407,11 +1414,11 @@ static void nbd_parse_filename(const char *filename, QDict *options,
     /* extract the host_spec - fail if it's not nbd:... */
     if (!strstart(file, "nbd:", &host_spec)) {
         error_setg(errp, "File name string for NBD must start with 'nbd:'");
-        goto out;
+        return;
     }
 
     if (!*host_spec) {
-        goto out;
+        return;
     }
 
     /* are we a UNIX or TCP socket? */
@@ -1431,9 +1438,6 @@ static void nbd_parse_filename(const char *filename, QDict *options,
     out_inet:
         qapi_free_InetSocketAddress(addr);
     }
-
-out:
-    g_free(file);
 }
 
 static bool nbd_process_legacy_socket_options(QDict *output_options,

blockdev-nbd.c

@@ -187,8 +187,7 @@ void qmp_nbd_server_add(const char *device, bool has_name, const char *name,
         writable = false;
     }
 
-    exp = nbd_export_new(bs, 0, len, name, NULL, bitmap,
-                         writable ? 0 : NBD_FLAG_READ_ONLY,
+    exp = nbd_export_new(bs, 0, len, name, NULL, bitmap, !writable, !writable,
                          NULL, false, on_eject_blk, errp);
     if (!exp) {
         return;

docs/interop/nbd.txt

@@ -53,3 +53,5 @@ the operation of that feature.
 * 2.12: NBD_CMD_BLOCK_STATUS for "base:allocation"
 * 3.0: NBD_OPT_STARTTLS with TLS Pre-Shared Keys (PSK),
 NBD_CMD_BLOCK_STATUS for "qemu:dirty-bitmap:", NBD_CMD_CACHE
+* 4.2: NBD_FLAG_CAN_MULTI_CONN for sharable read-only exports,
+NBD_CMD_FLAG_FAST_ZERO

include/block/nbd.h

@@ -140,6 +140,7 @@ enum {
     NBD_FLAG_CAN_MULTI_CONN_BIT     =  8, /* Multi-client cache consistent */
     NBD_FLAG_SEND_RESIZE_BIT        =  9, /* Send resize */
     NBD_FLAG_SEND_CACHE_BIT         = 10, /* Send CACHE (prefetch) */
+    NBD_FLAG_SEND_FAST_ZERO_BIT     = 11, /* FAST_ZERO flag for WRITE_ZEROES */
 };
 
 #define NBD_FLAG_HAS_FLAGS         (1 << NBD_FLAG_HAS_FLAGS_BIT)
@@ -153,6 +154,7 @@ enum {
 #define NBD_FLAG_CAN_MULTI_CONN    (1 << NBD_FLAG_CAN_MULTI_CONN_BIT)
 #define NBD_FLAG_SEND_RESIZE       (1 << NBD_FLAG_SEND_RESIZE_BIT)
 #define NBD_FLAG_SEND_CACHE        (1 << NBD_FLAG_SEND_CACHE_BIT)
+#define NBD_FLAG_SEND_FAST_ZERO    (1 << NBD_FLAG_SEND_FAST_ZERO_BIT)
 
 /* New-style handshake (global) flags, sent from server to client, and
    control what will happen during handshake phase. */
@@ -205,6 +207,7 @@ enum {
 #define NBD_CMD_FLAG_DF         (1 << 2) /* don't fragment structured read */
 #define NBD_CMD_FLAG_REQ_ONE    (1 << 3) /* only one extent in BLOCK_STATUS
                                           * reply chunk */
+#define NBD_CMD_FLAG_FAST_ZERO  (1 << 4) /* fail if WRITE_ZEROES is not fast */
 
 /* Supported request types */
 enum {
@@ -270,6 +273,7 @@ static inline bool nbd_reply_type_is_error(int type)
 #define NBD_EINVAL     22
 #define NBD_ENOSPC     28
 #define NBD_EOVERFLOW  75
+#define NBD_ENOTSUP    95
 #define NBD_ESHUTDOWN  108
 
 /* Details collected by NBD_OPT_EXPORT_NAME and NBD_OPT_GO */
@@ -326,7 +330,7 @@ typedef struct NBDClient NBDClient;
 
 NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
                           uint64_t size, const char *name, const char *desc,
-                          const char *bitmap, uint16_t nbdflags,
+                          const char *bitmap, bool readonly, bool shared,
                           void (*close)(NBDExport *), bool writethrough,
                           BlockBackend *on_eject_blk, Error **errp);
 void nbd_export_close(NBDExport *exp);

nbd/client.c

@@ -1,5 +1,5 @@
 /*
- *  Copyright (C) 2016-2018 Red Hat, Inc.
+ *  Copyright (C) 2016-2019 Red Hat, Inc.
  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
  *
  *  Network Block Device Client Side
@@ -142,17 +142,18 @@ static int nbd_receive_option_reply(QIOChannel *ioc, uint32_t opt,
     return 0;
 }
 
-/* If reply represents success, return 1 without further action.
- * If reply represents an error, consume the optional payload of
- * the packet on ioc.  Then return 0 for unsupported (so the client
- * can fall back to other approaches), or -1 with errp set for other
- * errors.
+/*
+ * If reply represents success, return 1 without further action.  If
+ * reply represents an error, consume the optional payload of the
+ * packet on ioc.  Then return 0 for unsupported (so the client can
+ * fall back to other approaches), where @strict determines if only
+ * ERR_UNSUP or all errors fit that category, or -1 with errp set for
+ * other errors.
  */
 static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply *reply,
-                                Error **errp)
+                                bool strict, Error **errp)
 {
-    char *msg = NULL;
-    int result = -1;
+    g_autofree char *msg = NULL;
 
     if (!(reply->type & (1 << 31))) {
         return 1;
@@ -163,26 +164,28 @@ static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply *reply,
             error_setg(errp, "server error %" PRIu32
                        " (%s) message is too long",
                        reply->type, nbd_rep_lookup(reply->type));
-            goto cleanup;
+            goto err;
         }
         msg = g_malloc(reply->length + 1);
         if (nbd_read(ioc, msg, reply->length, NULL, errp) < 0) {
             error_prepend(errp, "Failed to read option error %" PRIu32
                           " (%s) message: ",
                           reply->type, nbd_rep_lookup(reply->type));
-            goto cleanup;
+            goto err;
         }
         msg[reply->length] = '\0';
         trace_nbd_server_error_msg(reply->type,
                                    nbd_reply_type_lookup(reply->type), msg);
     }
 
-    switch (reply->type) {
-    case NBD_REP_ERR_UNSUP:
-        trace_nbd_reply_err_unsup(reply->option, nbd_opt_lookup(reply->option));
-        result = 0;
-        goto cleanup;
+    if (reply->type == NBD_REP_ERR_UNSUP || !strict) {
+        trace_nbd_reply_err_ignored(reply->option,
+                                    nbd_opt_lookup(reply->option),
+                                    reply->type, nbd_rep_lookup(reply->type));
+        return 0;
+    }
 
+    switch (reply->type) {
     case NBD_REP_ERR_POLICY:
         error_setg(errp, "Denied by server for option %" PRIu32 " (%s)",
                    reply->option, nbd_opt_lookup(reply->option));
@@ -227,12 +230,9 @@ static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply *reply,
         error_append_hint(errp, "server reported: %s\n", msg);
     }
 
- cleanup:
-    g_free(msg);
-    if (result < 0) {
-        nbd_send_opt_abort(ioc);
-    }
-    return result;
+ err:
+    nbd_send_opt_abort(ioc);
+    return -1;
 }
 
 /* nbd_receive_list:
@@ -247,18 +247,17 @@ static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply *reply,
 static int nbd_receive_list(QIOChannel *ioc, char **name, char **description,
                             Error **errp)
 {
-    int ret = -1;
     NBDOptionReply reply;
     uint32_t len;
     uint32_t namelen;
-    char *local_name = NULL;
-    char *local_desc = NULL;
+    g_autofree char *local_name = NULL;
+    g_autofree char *local_desc = NULL;
     int error;
 
     if (nbd_receive_option_reply(ioc, NBD_OPT_LIST, &reply, errp) < 0) {
         return -1;
     }
-    error = nbd_handle_reply_err(ioc, &reply, errp);
+    error = nbd_handle_reply_err(ioc, &reply, true, errp);
     if (error <= 0) {
         return error;
     }
@@ -298,32 +297,25 @@ static int nbd_receive_list(QIOChannel *ioc, char **name, char **description,
     local_name = g_malloc(namelen + 1);
     if (nbd_read(ioc, local_name, namelen, "export name", errp) < 0) {
         nbd_send_opt_abort(ioc);
-        goto out;
+        return -1;
     }
     local_name[namelen] = '\0';
     len -= namelen;
     if (len) {
         local_desc = g_malloc(len + 1);
         if (nbd_read(ioc, local_desc, len, "export description", errp) < 0) {
             nbd_send_opt_abort(ioc);
-            goto out;
+            return -1;
         }
         local_desc[len] = '\0';
     }
 
     trace_nbd_receive_list(local_name, local_desc ?: "");
-    *name = local_name;
-    local_name = NULL;
+    *name = g_steal_pointer(&local_name);
     if (description) {
-        *description = local_desc;
-        local_desc = NULL;
+        *description = g_steal_pointer(&local_desc);
     }
-    ret = 1;
-
- out:
-    g_free(local_name);
-    g_free(local_desc);
-    return ret;
+    return 1;
 }
 
 
@@ -371,7 +363,7 @@ static int nbd_opt_info_or_go(QIOChannel *ioc, uint32_t opt,
         if (nbd_receive_option_reply(ioc, opt, &reply, errp) < 0) {
             return -1;
         }
-        error = nbd_handle_reply_err(ioc, &reply, errp);
+        error = nbd_handle_reply_err(ioc, &reply, true, errp);
         if (error <= 0) {
             return error;
         }
@@ -546,12 +538,15 @@ static int nbd_receive_query_exports(QIOChannel *ioc,
     }
 }
 
-/* nbd_request_simple_option: Send an option request, and parse the reply
+/*
+ * nbd_request_simple_option: Send an option request, and parse the reply.
+ * @strict controls whether ERR_UNSUP or all errors produce 0 status.
  * return 1 for successful negotiation,
  *        0 if operation is unsupported,
  *        -1 with errp set for any other error
  */
-static int nbd_request_simple_option(QIOChannel *ioc, int opt, Error **errp)
+static int nbd_request_simple_option(QIOChannel *ioc, int opt, bool strict,
+                                     Error **errp)
 {
     NBDOptionReply reply;
     int error;
@@ -563,7 +558,7 @@ static int nbd_request_simple_option(QIOChannel *ioc, int opt, Error **errp)
     if (nbd_receive_option_reply(ioc, opt, &reply, errp) < 0) {
         return -1;
     }
-    error = nbd_handle_reply_err(ioc, &reply, errp);
+    error = nbd_handle_reply_err(ioc, &reply, strict, errp);
     if (error <= 0) {
         return error;
     }
@@ -595,7 +590,7 @@ static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
     QIOChannelTLS *tioc;
     struct NBDTLSHandshakeData data = { 0 };
 
-    ret = nbd_request_simple_option(ioc, NBD_OPT_STARTTLS, errp);
+    ret = nbd_request_simple_option(ioc, NBD_OPT_STARTTLS, true, errp);
     if (ret <= 0) {
         if (ret == 0) {
             error_setg(errp, "Server don't support STARTTLS option");
@@ -695,7 +690,7 @@ static int nbd_receive_one_meta_context(QIOChannel *ioc,
         return -1;
     }
 
-    ret = nbd_handle_reply_err(ioc, &reply, errp);
+    ret = nbd_handle_reply_err(ioc, &reply, false, errp);
     if (ret <= 0) {
         return ret;
     }
@@ -951,7 +946,7 @@ static int nbd_start_negotiate(AioContext *aio_context, QIOChannel *ioc,
             if (structured_reply) {
                 result = nbd_request_simple_option(ioc,
                                                    NBD_OPT_STRUCTURED_REPLY,
-                                                   errp);
+                                                   false, errp);
                 if (result < 0) {
                     return -EINVAL;
                 }

nbd/common.c

@@ -201,6 +201,8 @@ const char *nbd_err_lookup(int err)
         return "ENOSPC";
     case NBD_EOVERFLOW:
         return "EOVERFLOW";
+    case NBD_ENOTSUP:
+        return "ENOTSUP";
     case NBD_ESHUTDOWN:
         return "ESHUTDOWN";
     default:
@@ -231,6 +233,9 @@ int nbd_errno_to_system_errno(int err)
     case NBD_EOVERFLOW:
         ret = EOVERFLOW;
         break;
+    case NBD_ENOTSUP:
+        ret = ENOTSUP;
+        break;
     case NBD_ESHUTDOWN:
         ret = ESHUTDOWN;
         break;