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>

3 files changed, 19 insertions, 8 deletions

diff --git a/block/file-posix.c b/block/file-posix.c
index 71f168ee2f..87c5a4ccbd 100644
--- a/block/file-posix.c
+++ b/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;
         }
diff --git a/block/io.c b/block/io.c
index 0fa10831ed..16a598fd08 100644
--- a/block/io.c
+++ b/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;
 
diff --git a/block/nbd.c b/block/nbd.c
index beed46fb34..813c40d8f0 100644
--- a/block/nbd.c
+++ b/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,