vmsplice+splice experiment in stub_osd to test it too

40% CPU according to perf is lost inside do_splice() -> unix_stream_sendpage()
without io_uring and in various exc_page_fault() with io_uring

debian/patched-qemu.Dockerfile

@@ -7,11 +7,11 @@ ARG REL=
 
 WORKDIR /root
 
-RUN if [ "$REL" = "buster" ]; then \
+RUN if [ "$REL" = "buster" -o "$REL" = "bullseye" ]; then \
-        echo 'deb http://deb.debian.org/debian buster-backports main' >> /etc/apt/sources.list; \
+        echo "deb http://deb.debian.org/debian $REL-backports main" >> /etc/apt/sources.list; \
         echo >> /etc/apt/preferences; \
         echo 'Package: *' >> /etc/apt/preferences; \
-        echo 'Pin: release a=buster-backports' >> /etc/apt/preferences; \
+        echo "Pin: release a=$REL-backports" >> /etc/apt/preferences; \
         echo 'Pin-Priority: 500' >> /etc/apt/preferences; \
     fi; \
     grep '^deb ' /etc/apt/sources.list | perl -pe 's/^deb/deb-src/' >> /etc/apt/sources.list; \
@@ -27,15 +27,20 @@ RUN apt-get -y build-dep fio
 RUN apt-get --download-only source qemu
 RUN apt-get --download-only source fio
 
-ADD patches/qemu-5.0-vitastor.patch patches/qemu-5.1-vitastor.patch /root/vitastor/patches/
+ADD patches/qemu-5.0-vitastor.patch patches/qemu-5.1-vitastor.patch patches/qemu-6.1-vitastor.patch /root/vitastor/patches/
 RUN set -e; \
     mkdir -p /root/packages/qemu-$REL; \
     rm -rf /root/packages/qemu-$REL/*; \
     cd /root/packages/qemu-$REL; \
     dpkg-source -x /root/qemu*.dsc; \
-    if [ -d /root/packages/qemu-$REL/qemu-5.0 ]; then \
+    if ls -d /root/packages/qemu-$REL/qemu-5.0*; then \
-        cp /root/vitastor/patches/qemu-5.0-vitastor.patch /root/packages/qemu-$REL/qemu-5.0/debian/patches; \
+        D=$(ls -d /root/packages/qemu-$REL/qemu-5.0*); \
-        echo qemu-5.0-vitastor.patch >> /root/packages/qemu-$REL/qemu-5.0/debian/patches/series; \
+        cp /root/vitastor/patches/qemu-5.0-vitastor.patch $D/debian/patches; \
+        echo qemu-5.0-vitastor.patch >> $D/debian/patches/series; \
+    elif ls /root/packages/qemu-$REL/qemu-6.1*; then \
+        D=$(ls -d /root/packages/qemu-$REL/qemu-6.1*); \
+        cp /root/vitastor/patches/qemu-6.1-vitastor.patch $D/debian/patches; \
+        echo qemu-6.1-vitastor.patch >> $D/debian/patches/series; \
     else \
         cp /root/vitastor/patches/qemu-5.1-vitastor.patch /root/packages/qemu-$REL/qemu-*/debian/patches; \
         P=`ls -d /root/packages/qemu-$REL/qemu-*/debian/patches`; \

patches/cinder-vitastor.py

@@ -489,7 +489,7 @@ class VitastorDriver(driver.CloneableImageVD,
                 # FIXME use etcd_address in qemu driver
                 kk = 'etcd_host'
             if v:
-                args += ':'+kk+'='+v.replace(':', '\\:')
+                args += ':'+kk.replace('_', '-')+'='+v.replace(':', '\\:')
         return args
 
     def delete_volume(self, volume):

patches/libvirt-5.0-vitastor.diff

@@ -245,9 +245,9 @@ index cbf0aa4..096700d 100644
 +
 +    if (virJSONValueObjectCreate(&ret,
 +                                 "s:driver", "vitastor",
-+                                 "S:etcd_host", etcd,
++                                 "S:etcd-host", etcd,
-+                                 "S:etcd_prefix", src->relPath,
++                                 "S:etcd-prefix", src->relPath,
-+                                 "S:config_path", src->configFile,
++                                 "S:config-path", src->configFile,
 +                                 "s:image", src->path,
 +                                 NULL) < 0)
 +        goto cleanup;
@@ -293,7 +293,7 @@ index 822d5f8..e375cef 100644
 +            virBufferStrcat(&buf, "vitastor:image=", src->path, NULL);
 +
 +            if (src->nhosts > 0) {
-+                virBufferAddLit(&buf, ":etcd_host=");
++                virBufferAddLit(&buf, ":etcd-host=");
 +                for (i = 0; i < src->nhosts; i++) {
 +                    if (i)
 +                        virBufferAddLit(&buf, ",");
@@ -311,10 +311,10 @@ index 822d5f8..e375cef 100644
 +            }
 +
 +            if (src->configFile)
-+                virBufferEscape(&buf, '\\', ":", ":config_path=%s", src->configFile);
++                virBufferEscape(&buf, '\\', ":", ":config-path=%s", src->configFile);
 +
 +            if (src->relPath)
-+                virBufferEscape(&buf, '\\', ":", ":etcd_prefix=%s", src->relPath);
++                virBufferEscape(&buf, '\\', ":", ":etcd-prefix=%s", src->relPath);
 +
 +            ret = virBufferContentAndReset(&buf);
 +            break;
@@ -438,16 +438,16 @@ index bd4b027..b323cd6 100644
 +        if (STRPREFIX(p, "image=")) {
 +            if (VIR_STRDUP(src->path, p + strlen("image=")) < 0)
 +                return -1;
-+        } else if (STRPREFIX(p, "etcd_prefix=")) {
++        } else if (STRPREFIX(p, "etcd-prefix=")) {
-+            if (VIR_STRDUP(src->relPath, p + strlen("etcd_prefix=")) < 0)
++            if (VIR_STRDUP(src->relPath, p + strlen("etcd-prefix=")) < 0)
 +                return -1;
-+        } else if (STRPREFIX(p, "config_file=")) {
++        } else if (STRPREFIX(p, "config-path=")) {
-+            if (VIR_STRDUP(src->configFile, p + strlen("config_file=")) < 0)
++            if (VIR_STRDUP(src->configFile, p + strlen("config-path=")) < 0)
 +                return -1;
-+        } else if (STRPREFIX(p, "etcd_host=")) {
++        } else if (STRPREFIX(p, "etcd-host=")) {
 +            char *h, *sep;
 +
-+            h = p + strlen("etcd_host=");
++            h = p + strlen("etcd-host=");
 +            while (h < e) {
 +                for (sep = h; sep < e; ++sep) {
 +                    if (*sep == '\\' && (sep[1] == ',' ||
@@ -507,8 +507,8 @@ index bd4b027..b323cd6 100644
 +{
 +    const char *filename;
 +    const char *image = virJSONValueObjectGetString(json, "image");
-+    const char *conf = virJSONValueObjectGetString(json, "config_path");
++    const char *conf = virJSONValueObjectGetString(json, "config-path");
-+    const char *etcd_prefix = virJSONValueObjectGetString(json, "etcd_prefix");
++    const char *etcd_prefix = virJSONValueObjectGetString(json, "etcd-prefix");
 +    virJSONValuePtr servers = virJSONValueObjectGetArray(json, "server");
 +    size_t nservers;
 +    size_t i;

patches/libvirt-7.0-vitastor.diff

@@ -244,9 +244,9 @@ index f9c6da2..922dde5 100644
 +    }
 +
 +    if (virJSONValueObjectCreate(&ret,
-+                                 "S:etcd_host", etcd,
++                                 "S:etcd-host", etcd,
-+                                 "S:etcd_prefix", src->query,
++                                 "S:etcd-prefix", src->query,
-+                                 "S:config_path", src->configFile,
++                                 "S:config-path", src->configFile,
 +                                 "s:image", src->path,
 +                                 NULL) < 0)
 +        return NULL;
@@ -311,7 +311,7 @@ index 6f970a3..10b39ca 100644
 +            virBufferStrcat(&buf, "vitastor:image=", src->path, NULL);
 +
 +            if (src->nhosts > 0) {
-+                virBufferAddLit(&buf, ":etcd_host=");
++                virBufferAddLit(&buf, ":etcd-host=");
 +                for (i = 0; i < src->nhosts; i++) {
 +                    if (i)
 +                        virBufferAddLit(&buf, ",");
@@ -329,10 +329,10 @@ index 6f970a3..10b39ca 100644
 +            }
 +
 +            if (src->configFile)
-+                virBufferEscape(&buf, '\\', ":", ":config_path=%s", src->configFile);
++                virBufferEscape(&buf, '\\', ":", ":config-path=%s", src->configFile);
 +
 +            if (src->query)
-+                virBufferEscape(&buf, '\\', ":", ":etcd_prefix=%s", src->query);
++                virBufferEscape(&buf, '\\', ":", ":etcd-prefix=%s", src->query);
 +
 +            ret = virBufferContentAndReset(&buf);
 +            break;
@@ -462,14 +462,14 @@ index 0d3c2af..36e3afc 100644
 +
 +        if (STRPREFIX(p, "image=")) {
 +            src->path = g_strdup(p + strlen("image="));
-+        } else if (STRPREFIX(p, "etcd_prefix=")) {
++        } else if (STRPREFIX(p, "etcd-prefix=")) {
-+            src->query = g_strdup(p + strlen("etcd_prefix="));
++            src->query = g_strdup(p + strlen("etcd-prefix="));
-+        } else if (STRPREFIX(p, "config_file=")) {
++        } else if (STRPREFIX(p, "config-path=")) {
-+            src->configFile = g_strdup(p + strlen("config_file="));
++            src->configFile = g_strdup(p + strlen("config-path="));
-+        } else if (STRPREFIX(p, "etcd_host=")) {
++        } else if (STRPREFIX(p, "etcd-host=")) {
 +            char *h, *sep;
 +
-+            h = p + strlen("etcd_host=");
++            h = p + strlen("etcd-host=");
 +            while (h < e) {
 +                for (sep = h; sep < e; ++sep) {
 +                    if (*sep == '\\' && (sep[1] == ',' ||
@@ -526,8 +526,8 @@ index 0d3c2af..36e3afc 100644
 +{
 +    const char *filename;
 +    const char *image = virJSONValueObjectGetString(json, "image");
-+    const char *conf = virJSONValueObjectGetString(json, "config_path");
++    const char *conf = virJSONValueObjectGetString(json, "config-path");
-+    const char *etcd_prefix = virJSONValueObjectGetString(json, "etcd_prefix");
++    const char *etcd_prefix = virJSONValueObjectGetString(json, "etcd-prefix");
 +    virJSONValuePtr servers = virJSONValueObjectGetArray(json, "server");
 +    size_t nservers;
 +    size_t i;

patches/libvirt-7.5-vitastor.diff

@@ -276,9 +276,9 @@ index 6627d04..c33f428 100644
 +    }
 +
 +    if (virJSONValueObjectCreate(&ret,
-+                                 "S:etcd_host", etcd,
++                                 "S:etcd-host", etcd,
-+                                 "S:etcd_prefix", src->query,
++                                 "S:etcd-prefix", src->query,
-+                                 "S:config_path", src->configFile,
++                                 "S:config-path", src->configFile,
 +                                 "s:image", src->path,
 +                                 NULL) < 0)
 +        return NULL;
@@ -343,7 +343,7 @@ index ea51369..8258632 100644
 +            virBufferStrcat(&buf, "vitastor:image=", src->path, NULL);
 +
 +            if (src->nhosts > 0) {
-+                virBufferAddLit(&buf, ":etcd_host=");
++                virBufferAddLit(&buf, ":etcd-host=");
 +                for (i = 0; i < src->nhosts; i++) {
 +                    if (i)
 +                        virBufferAddLit(&buf, ",");
@@ -361,10 +361,10 @@ index ea51369..8258632 100644
 +            }
 +
 +            if (src->configFile)
-+                virBufferEscape(&buf, '\\', ":", ":config_path=%s", src->configFile);
++                virBufferEscape(&buf, '\\', ":", ":config-path=%s", src->configFile);
 +
 +            if (src->query)
-+                virBufferEscape(&buf, '\\', ":", ":etcd_prefix=%s", src->query);
++                virBufferEscape(&buf, '\\', ":", ":etcd-prefix=%s", src->query);
 +
 +            ret = virBufferContentAndReset(&buf);
 +            break;
@@ -474,14 +474,14 @@ index e48ae72..d7a9b72 100644
 +
 +        if (STRPREFIX(p, "image=")) {
 +            src->path = g_strdup(p + strlen("image="));
-+        } else if (STRPREFIX(p, "etcd_prefix=")) {
++        } else if (STRPREFIX(p, "etcd-prefix=")) {
-+            src->query = g_strdup(p + strlen("etcd_prefix="));
++            src->query = g_strdup(p + strlen("etcd-prefix="));
-+        } else if (STRPREFIX(p, "config_file=")) {
++        } else if (STRPREFIX(p, "config-path=")) {
-+            src->configFile = g_strdup(p + strlen("config_file="));
++            src->configFile = g_strdup(p + strlen("config-path="));
-+        } else if (STRPREFIX(p, "etcd_host=")) {
++        } else if (STRPREFIX(p, "etcd-host=")) {
 +            char *h, *sep;
 +
-+            h = p + strlen("etcd_host=");
++            h = p + strlen("etcd-host=");
 +            while (h < e) {
 +                for (sep = h; sep < e; ++sep) {
 +                    if (*sep == '\\' && (sep[1] == ',' ||
@@ -538,8 +538,8 @@ index e48ae72..d7a9b72 100644
 +{
 +    const char *filename;
 +    const char *image = virJSONValueObjectGetString(json, "image");
-+    const char *conf = virJSONValueObjectGetString(json, "config_path");
++    const char *conf = virJSONValueObjectGetString(json, "config-path");
-+    const char *etcd_prefix = virJSONValueObjectGetString(json, "etcd_prefix");
++    const char *etcd_prefix = virJSONValueObjectGetString(json, "etcd-prefix");
 +    virJSONValue *servers = virJSONValueObjectGetArray(json, "server");
 +    size_t nservers;
 +    size_t i;

patches/nova-20.diff

@@ -124,7 +124,7 @@ index 391231c527..34dc60dcdd 100644
 +                            if kk == 'etcd_address':
 +                                # FIXME use etcd_address in qemu driver
 +                                kk = 'etcd_host'
-+                            path += ":"+kk+"="+connection_info['data'][k].replace(':', '\\:')
++                            path += ":"+kk.replace('_', '-')+"="+connection_info['data'][k].replace(':', '\\:')
                  else:
                      path = 'unknown'
                      raise exception.DiskNotFound(location='unknown')

patches/qemu-3.1-vitastor.patch

@@ -23,18 +23,18 @@ Index: qemu-3.1+dfsg/qapi/block-core.json
 +# @inode:       Inode number
 +# @pool:        Pool ID
 +# @size:        Desired image size in bytes
-+# @config_path: Path to Vitastor configuration
++# @config-path: Path to Vitastor configuration
-+# @etcd_host:   etcd connection address(es)
++# @etcd-host:   etcd connection address(es)
-+# @etcd_prefix: etcd key/value prefix
++# @etcd-prefix: etcd key/value prefix
 +##
 +{ 'struct': 'BlockdevOptionsVitastor',
 +  'data': { '*inode': 'uint64',
 +            '*pool': 'uint64',
 +            '*size': 'uint64',
 +            '*image': 'str',
-+            '*config_path': 'str',
++            '*config-path': 'str',
-+            '*etcd_host': 'str',
++            '*etcd-host': 'str',
-+            '*etcd_prefix': 'str' } }
++            '*etcd-prefix': 'str' } }
 +
 +##
  # @ReplicationMode:

patches/qemu-4.2-vitastor.patch

@@ -23,18 +23,18 @@ Index: qemu/qapi/block-core.json
 +# @inode:       Inode number
 +# @pool:        Pool ID
 +# @size:        Desired image size in bytes
-+# @config_path: Path to Vitastor configuration
++# @config-path: Path to Vitastor configuration
-+# @etcd_host:   etcd connection address(es)
++# @etcd-host:   etcd connection address(es)
-+# @etcd_prefix: etcd key/value prefix
++# @etcd-prefix: etcd key/value prefix
 +##
 +{ 'struct': 'BlockdevOptionsVitastor',
 +  'data': { '*inode': 'uint64',
 +            '*pool': 'uint64',
 +            '*size': 'uint64',
 +            '*image': 'str',
-+            '*config_path': 'str',
++            '*config-path': 'str',
-+            '*etcd_host': 'str',
++            '*etcd-host': 'str',
-+            '*etcd_prefix': 'str' } }
++            '*etcd-prefix': 'str' } }
 +
 +##
  # @ReplicationMode:

patches/qemu-5.0-vitastor.patch

@@ -23,18 +23,18 @@ Index: qemu/qapi/block-core.json
 +# @inode:       Inode number
 +# @pool:        Pool ID
 +# @size:        Desired image size in bytes
-+# @config_path: Path to Vitastor configuration
++# @config-path: Path to Vitastor configuration
-+# @etcd_host:   etcd connection address(es)
++# @etcd-host:   etcd connection address(es)
-+# @etcd_prefix: etcd key/value prefix
++# @etcd-prefix: etcd key/value prefix
 +##
 +{ 'struct': 'BlockdevOptionsVitastor',
 +  'data': { '*inode': 'uint64',
 +            '*pool': 'uint64',
 +            '*size': 'uint64',
 +            '*image': 'str',
-+            '*config_path': 'str',
++            '*config-path': 'str',
-+            '*etcd_host': 'str',
++            '*etcd-host': 'str',
-+            '*etcd_prefix': 'str' } }
++            '*etcd-prefix': 'str' } }
 +
 +##
  # @ReplicationMode:

patches/qemu-5.1-vitastor.patch

@@ -23,18 +23,18 @@ Index: qemu-5.1+dfsg/qapi/block-core.json
 +# @inode:       Inode number
 +# @pool:        Pool ID
 +# @size:        Desired image size in bytes
-+# @config_path: Path to Vitastor configuration
++# @config-path: Path to Vitastor configuration
-+# @etcd_host:   etcd connection address(es)
++# @etcd-host:   etcd connection address(es)
-+# @etcd_prefix: etcd key/value prefix
++# @etcd-prefix: etcd key/value prefix
 +##
 +{ 'struct': 'BlockdevOptionsVitastor',
 +  'data': { '*inode': 'uint64',
 +            '*pool': 'uint64',
 +            '*size': 'uint64',
 +            '*image': 'str',
-+            '*config_path': 'str',
++            '*config-path': 'str',
-+            '*etcd_host': 'str',
++            '*etcd-host': 'str',
-+            '*etcd_prefix': 'str' } }
++            '*etcd-prefix': 'str' } }
 +
 +##
  # @ReplicationMode:

patches/qemu-6.1-vitastor.patch

@@ -0,0 +1,88 @@
+Index: qemu-6.1+dfsg/qapi/block-core.json
+===================================================================
+--- qemu-6.1+dfsg.orig/qapi/block-core.json
++++ qemu-6.1+dfsg/qapi/block-core.json
+@@ -2838,7 +2838,7 @@
+             'luks', 'nbd', 'nfs', 'null-aio', 'null-co', 'nvme', 'parallels',
+             'preallocate', 'qcow', 'qcow2', 'qed', 'quorum', 'raw', 'rbd',
+             { 'name': 'replication', 'if': 'defined(CONFIG_REPLICATION)' },
+-            'ssh', 'throttle', 'vdi', 'vhdx', 'vmdk', 'vpc', 'vvfat' ] }
++            'ssh', 'throttle', 'vdi', 'vhdx', 'vitastor', 'vmdk', 'vpc', 'vvfat' ] }
+ 
+ ##
+ # @BlockdevOptionsFile:
+@@ -3763,6 +3763,28 @@
+             '*server': ['InetSocketAddressBase'] } }
+ 
+ ##
++# @BlockdevOptionsVitastor:
++#
++# Driver specific block device options for vitastor
++#
++# @image:       Image name
++# @inode:       Inode number
++# @pool:        Pool ID
++# @size:        Desired image size in bytes
++# @config-path: Path to Vitastor configuration
++# @etcd-host:   etcd connection address(es)
++# @etcd-prefix: etcd key/value prefix
++##
++{ 'struct': 'BlockdevOptionsVitastor',
++  'data': { '*inode': 'uint64',
++            '*pool': 'uint64',
++            '*size': 'uint64',
++            '*image': 'str',
++            '*config-path': 'str',
++            '*etcd-host': 'str',
++            '*etcd-prefix': 'str' } }
++
++##
+ # @ReplicationMode:
+ #
+ # An enumeration of replication modes.
+@@ -4134,6 +4156,7 @@
+       'throttle':   'BlockdevOptionsThrottle',
+       'vdi':        'BlockdevOptionsGenericFormat',
+       'vhdx':       'BlockdevOptionsGenericFormat',
++      'vitastor':   'BlockdevOptionsVitastor',
+       'vmdk':       'BlockdevOptionsGenericCOWFormat',
+       'vpc':        'BlockdevOptionsGenericFormat',
+       'vvfat':      'BlockdevOptionsVVFAT'
+@@ -4523,6 +4546,17 @@
+             '*encrypt' :        'RbdEncryptionCreateOptions' } }
+ 
+ ##
++# @BlockdevCreateOptionsVitastor:
++#
++# Driver specific image creation options for Vitastor.
++#
++# @size: Size of the virtual disk in bytes
++##
++{ 'struct': 'BlockdevCreateOptionsVitastor',
++  'data': { 'location':         'BlockdevOptionsVitastor',
++            'size':             'size' } }
++
++##
+ # @BlockdevVmdkSubformat:
+ #
+ # Subformat options for VMDK images
+@@ -4718,6 +4752,7 @@
+       'ssh':            'BlockdevCreateOptionsSsh',
+       'vdi':            'BlockdevCreateOptionsVdi',
+       'vhdx':           'BlockdevCreateOptionsVhdx',
++      'vitastor':       'BlockdevCreateOptionsVitastor',
+       'vmdk':           'BlockdevCreateOptionsVmdk',
+       'vpc':            'BlockdevCreateOptionsVpc'
+   } }
+Index: qemu-6.1+dfsg/scripts/modules/module_block.py
+===================================================================
+--- qemu-6.1+dfsg.orig/scripts/modules/module_block.py
++++ qemu-6.1+dfsg/scripts/modules/module_block.py
+@@ -86,6 +86,7 @@ if __name__ == '__main__':
+     output_file = sys.argv[1]
+     with open(output_file, 'w') as fheader:
+         print_top(fheader)
++        add_module(fheader, "vitastor", "vitastor", "vitastor")
+ 
+         for filename in sys.argv[2:]:
+             if os.path.isfile(filename):

src/CMakeLists.txt

@@ -145,7 +145,7 @@ endif (${WITH_FIO})
 
 # vitastor-nbd
 add_executable(vitastor-nbd
-	nbd_proxy.cpp
+	nbd_proxy.cpp mmap_manager.cpp
 )
 target_link_libraries(vitastor-nbd
 	vitastor_client
@@ -188,7 +188,7 @@ endif (${WITH_QEMU})
 ### Test stubs
 
 # stub_osd, stub_bench, osd_test
-add_executable(stub_osd stub_osd.cpp rw_blocking.cpp)
+add_executable(stub_osd stub_osd.cpp rw_blocking.cpp mmap_manager.cpp)
 target_link_libraries(stub_osd tcmalloc_minimal)
 add_executable(stub_bench stub_bench.cpp rw_blocking.cpp)
 target_link_libraries(stub_bench tcmalloc_minimal)

src/mmap_manager.cpp

@@ -0,0 +1,82 @@
+#include <stdexcept>
+#include <cassert>
+#include <sys/mman.h>
+#include "mmap_manager.h"
+
+mmap_manager_t::mmap_manager_t(uint64_t mmap_size)
+{
+    this->mmap_size = mmap_size;
+}
+
+mmap_manager_t::~mmap_manager_t()
+{
+    for (auto & kv: past_buffers)
+    {
+        munmap(kv.second.addr, kv.second.size);
+    }
+    if (active_buffer.addr != NULL)
+    {
+        munmap(active_buffer.addr, active_buffer.size);
+    }
+}
+
+void *mmap_manager_t::alloc(uint64_t size)
+{
+    if (!active_buffer.addr || (active_buffer.pos + size) > active_buffer.size)
+    {
+        if (active_buffer.addr)
+        {
+            if (active_buffer.freed >= active_buffer.pos)
+                munmap(active_buffer.addr, active_buffer.size);
+            else
+                past_buffers[active_buffer.addr] = active_buffer;
+            active_buffer = { 0 };
+        }
+        uint64_t new_size = size < mmap_size ? mmap_size : size;
+        void *buf = mmap(NULL, new_size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+        if (!buf)
+            throw std::runtime_error(std::string("can't mmap "+std::to_string(new_size)+" bytes"));
+        active_buffer = {
+            .addr = buf,
+            .size = new_size,
+            .freed = 0,
+            .pos = 0,
+        };
+    }
+    void *res = active_buffer.addr + active_buffer.pos;
+    active_buffer.pos += size;
+    return res;
+}
+
+void mmap_manager_t::free(void *addr, uint64_t size)
+{
+    auto it = past_buffers.upper_bound(addr);
+    if (it != past_buffers.begin())
+    {
+        if (it == past_buffers.end())
+        {
+            it--;
+            if (addr < it->second.addr || addr >= it->second.addr+it->second.size)
+                it = past_buffers.end();
+        }
+        else
+            it--;
+    }
+    else
+        it = past_buffers.end();
+    if (it != past_buffers.end())
+    {
+        assert(addr >= it->second.addr && addr+size <= it->second.addr+it->second.size);
+        it->second.freed += size;
+        if (it->second.freed >= it->second.pos)
+        {
+            munmap(it->second.addr, it->second.size);
+            past_buffers.erase(it);
+        }
+    }
+    else
+    {
+        assert(addr < active_buffer.addr+active_buffer.size);
+        active_buffer.freed += size;
+    }
+}

src/mmap_manager.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <stdint.h>
+#include <map>
+
+struct mmap_buffer_t
+{
+    void *addr = NULL;
+    uint64_t size = 0;
+    uint64_t freed = 0;
+    uint64_t pos = 0;
+};
+
+class mmap_manager_t
+{
+protected:
+    uint64_t mmap_size = 32*1024*1024;
+    std::map<void*, mmap_buffer_t> past_buffers;
+    mmap_buffer_t active_buffer;
+
+public:
+    mmap_manager_t(uint64_t mmap_size = 32*1024*1024);
+    ~mmap_manager_t();
+    void *alloc(uint64_t size);
+    void free(void *addr, uint64_t size);
+};

src/nbd_proxy.cpp

@@ -17,6 +17,8 @@
 
 #include "epoll_manager.h"
 #include "cluster_client.h"
+#include "mmap_manager.h"
+#include <stdexcept>
 
 #ifndef MSG_ZEROCOPY
 #define MSG_ZEROCOPY 0
@@ -24,6 +26,24 @@
 
 const char *exe_name = NULL;
 
+static inline void my_uring_prep_splice(struct io_uring_sqe *sqe,
+					int fd_in, int64_t off_in,
+					int fd_out, int64_t off_out,
+					unsigned int nbytes,
+					unsigned int splice_flags)
+{
+	my_uring_prep_rw(IORING_OP_SPLICE, sqe, fd_out, NULL, nbytes, (__u64) off_out);
+	sqe->splice_off_in = (__u64) off_in;
+	sqe->splice_fd_in = fd_in;
+	sqe->splice_flags = splice_flags;
+}
+
+struct buf_to_free_t
+{
+    void *buf = NULL;
+    uint64_t unmap = 0;
+};
+
 class nbd_proxy
 {
 protected:
@@ -38,7 +58,7 @@ protected:
     ring_consumer_t consumer;
 
     std::vector<iovec> send_list, next_send_list;
-    std::vector<void*> to_free;
+    std::vector<buf_to_free_t> to_free;
     int nbd_fd = -1;
     void *recv_buf = NULL;
     int receive_buffer_size = 9000;
@@ -51,6 +71,10 @@ protected:
     msghdr read_msg = { 0 }, send_msg = { 0 };
     iovec read_iov = { 0 };
 
+    mmap_manager_t mm;
+    int pipe_fd[2];
+    int vmspliced = 0;
+
 public:
     static json11::Json::object parse_args(int narg, const char *args[])
     {
@@ -174,6 +198,12 @@ public:
                 exit(1);
             }
         }
+        // Create pipe for splicing
+        if (pipe(pipe_fd) < 0)
+        {
+            fprintf(stderr, "pipe failed: %s\n", strerror(errno));
+            exit(1);
+        }
         // Create client
         ringloop = new ring_loop_t(512);
         epmgr = new epoll_manager_t(ringloop);
@@ -522,16 +552,76 @@ protected:
         {
             return;
         }
-        io_uring_sqe* sqe = ringloop->get_sqe();
+        int i;
+        //uint64_t len = 0;
+        for (i = 0; i < send_list.size(); i++)
+        {
+            if (to_free[i].unmap)
+            {
+                break;
+            }
+            //len += send_list[i].iov_len;
+        }
+        //if (true)
+        if (i > 0)
+        {
+            /*io_uring_sqe* sqe = ringloop->get_sqe();
             if (!sqe)
             {
                 return;
             }
             ring_data_t* data = ((ring_data_t*)sqe->user_data);
-        data->callback = [this](ring_data_t *data) { handle_send(data->res); };
+            data->callback = [this](ring_data_t *data) { handle_send(data->res); };*/
             send_msg.msg_iov = send_list.data();
-        send_msg.msg_iovlen = send_list.size();
+            //send_msg.msg_iovlen = send_list.size();
-        my_uring_prep_sendmsg(sqe, nbd_fd, &send_msg, MSG_ZEROCOPY);
+            send_msg.msg_iovlen = i;
+            //my_uring_prep_sendmsg(sqe, nbd_fd, &send_msg, MSG_ZEROCOPY);
+            int res = sendmsg(nbd_fd, &send_msg, MSG_ZEROCOPY);
+            if (res < 0)
+                res = -errno;
+            handle_send(res);
+            //int r = sendmsg(int sockfd, const struct msghdr *msg, int flags);
+        }
+        else
+        {
+            io_uring_sqe* sqe = ringloop->get_sqe();
+            if (!sqe)
+            {
+                return;
+            }
+            if (vmspliced <= 0)
+            {
+                vmspliced = vmsplice(pipe_fd[1], send_list.data(), 1, SPLICE_F_GIFT);
+                if (vmspliced < 0)
+                {
+                    throw std::runtime_error(std::string("vmsplice: ")+strerror(errno));
+                }
+            }
+            send_msg.msg_iovlen = 1;
+            ring_data_t* data = ((ring_data_t*)sqe->user_data);
+            data->callback = [this](ring_data_t *data)
+            {
+                if (data->res > 0)
+                    vmspliced -= data->res;
+                handle_send(data->res);
+            };
+            my_uring_prep_splice(sqe, pipe_fd[0], -1l, nbd_fd, -1l, vmspliced, SPLICE_F_MOVE);
+            /*int sent = res, spl = res;
+            while (spl > 0)
+            {
+                res = splice(pipe_fd[0], NULL, nbd_fd, NULL, spl, SPLICE_F_MOVE);
+                if (res < 0)
+                {
+                    if (errno != EAGAIN)
+                        throw std::runtime_error(std::string("splice: ")+strerror(errno));
+                }
+                else
+                {
+                    spl -= res;
+                }
+            }
+            handle_send(sent);*/
+        }
     }
 
     void handle_send(int result)
@@ -547,7 +637,10 @@ protected:
         {
             if (result >= send_list[to_eat].iov_len)
             {
-                free(to_free[to_eat]);
+                if (to_free[to_eat].unmap)
+                    mm.free(to_free[to_eat].buf, to_free[to_eat].unmap);
+                else
+                    free(to_free[to_eat].buf);
                 result -= send_list[to_eat].iov_len;
                 to_eat++;
             }
@@ -659,6 +752,7 @@ protected:
             printf("request %lx +%x %lx\n", be64toh(cur_req.from), be32toh(cur_req.len), handle);
 #endif
             void *buf = NULL;
+            nbd_reply *reply = NULL;
             cluster_op_t *op = new cluster_op_t;
             if (req_type == NBD_CMD_READ || req_type == NBD_CMD_WRITE)
             {
@@ -666,36 +760,51 @@ protected:
                 op->inode = inode ? inode : watch->cfg.num;
                 op->offset = be64toh(cur_req.from);
                 op->len = be32toh(cur_req.len);
+                if (req_type == NBD_CMD_WRITE)
+                {
                     buf = malloc_or_die(sizeof(nbd_reply) + op->len);
+                    reply = (nbd_reply*)buf;
                     op->iov.push_back(buf + sizeof(nbd_reply), op->len);
                 }
+                else
+                {
+                    buf = mm.alloc(op->len);
+                    reply = (nbd_reply*)malloc_or_die(sizeof(nbd_reply));
+                    op->iov.push_back(buf, op->len);
+                }
+            }
             else if (req_type == NBD_CMD_FLUSH)
             {
                 op->opcode = OSD_OP_SYNC;
-                buf = malloc_or_die(sizeof(nbd_reply));
+                reply = (nbd_reply*)malloc_or_die(sizeof(nbd_reply));
             }
-            op->callback = [this, buf, handle](cluster_op_t *op)
+            op->callback = [this, buf, reply, handle](cluster_op_t *op)
             {
 #ifdef DEBUG
                 printf("reply %lx e=%d\n", handle, op->retval);
 #endif
-                nbd_reply *reply = (nbd_reply*)buf;
                 reply->magic = htobe32(NBD_REPLY_MAGIC);
                 memcpy(reply->handle, &handle, 8);
                 reply->error = htobe32(op->retval < 0 ? -op->retval : 0);
                 auto & to_list = send_msg.msg_iovlen > 0 ? next_send_list : send_list;
-                if (op->retval < 0 || op->opcode != OSD_OP_READ)
+                to_list.push_back((iovec){ .iov_base = reply, .iov_len = sizeof(nbd_reply) });
-                    to_list.push_back({ .iov_base = buf, .iov_len = sizeof(nbd_reply) });
+                to_free.push_back((buf_to_free_t){ .buf = reply, .unmap = 0 });
-                else
+                if (op->retval >= 0 && op->opcode == OSD_OP_READ)
-                    to_list.push_back({ .iov_base = buf, .iov_len = sizeof(nbd_reply) + op->len });
+                {
-                to_free.push_back(buf);
+                    to_list.push_back((iovec){ .iov_base = buf, .iov_len = op->len });
+                    to_free.push_back((buf_to_free_t){ .buf = buf, .unmap = op->len });
+                }
+                else if (op->opcode == OSD_OP_READ)
+                {
+                    mm.free(buf, op->len);
+                }
                 delete op;
                 ringloop->wakeup();
             };
             if (req_type == NBD_CMD_WRITE)
             {
                 cur_op = op;
-                cur_buf = buf + sizeof(nbd_reply);
+                cur_buf = buf;
                 cur_left = op->len;
                 read_state = CL_READ_DATA;
             }

src/qemu_driver.c

@@ -132,16 +132,19 @@ static void vitastor_parse_filename(const char *filename, QDict *options, Error
             error_setg(errp, "conf option %s has no value", name);
             break;
         }
+        for (int i = 0; i < strlen(name); i++)
+            if (name[i] == '_')
+                name[i] = '-';
         qemu_vitastor_unescape(name);
         value = qemu_vitastor_next_tok(p, ':', &p);
         qemu_vitastor_unescape(value);
         if (!strcmp(name, "inode") ||
             !strcmp(name, "pool") ||
             !strcmp(name, "size") ||
-            !strcmp(name, "use_rdma") ||
+            !strcmp(name, "use-rdma") ||
-            !strcmp(name, "rdma_port_num") ||
+            !strcmp(name, "rdma-port_num") ||
-            !strcmp(name, "rdma_gid_index") ||
+            !strcmp(name, "rdma-gid-index") ||
-            !strcmp(name, "rdma_mtu"))
+            !strcmp(name, "rdma-mtu"))
         {
             unsigned long long num_val;
             if (parse_uint_full(value, &num_val, 0))
@@ -202,15 +205,15 @@ static int vitastor_file_open(BlockDriverState *bs, QDict *options, int flags, E
     VitastorClient *client = bs->opaque;
     int64_t ret = 0;
     qemu_mutex_init(&client->mutex);
-    client->config_path = g_strdup(qdict_get_try_str(options, "config_path"));
+    client->config_path = g_strdup(qdict_get_try_str(options, "config-path"));
     // FIXME: Rename to etcd_address
-    client->etcd_host = g_strdup(qdict_get_try_str(options, "etcd_host"));
+    client->etcd_host = g_strdup(qdict_get_try_str(options, "etcd-host"));
-    client->etcd_prefix = g_strdup(qdict_get_try_str(options, "etcd_prefix"));
+    client->etcd_prefix = g_strdup(qdict_get_try_str(options, "etcd-prefix"));
-    client->use_rdma = qdict_get_try_int(options, "use_rdma", -1);
+    client->use_rdma = qdict_get_try_int(options, "use-rdma", -1);
-    client->rdma_device = g_strdup(qdict_get_try_str(options, "rdma_device"));
+    client->rdma_device = g_strdup(qdict_get_try_str(options, "rdma-device"));
-    client->rdma_port_num = qdict_get_try_int(options, "rdma_port_num", 0);
+    client->rdma_port_num = qdict_get_try_int(options, "rdma-port-num", 0);
-    client->rdma_gid_index = qdict_get_try_int(options, "rdma_gid_index", 0);
+    client->rdma_gid_index = qdict_get_try_int(options, "rdma-gid-index", 0);
-    client->rdma_mtu = qdict_get_try_int(options, "rdma_mtu", 0);
+    client->rdma_mtu = qdict_get_try_int(options, "rdma-mtu", 0);
     client->proxy = vitastor_c_create_qemu(
         (QEMUSetFDHandler*)aio_set_fd_handler, bdrv_get_aio_context(bs), client->config_path, client->etcd_host, client->etcd_prefix,
         client->use_rdma, client->rdma_device, client->rdma_port_num, client->rdma_gid_index, client->rdma_mtu, 0
@@ -264,14 +267,14 @@ static int vitastor_file_open(BlockDriverState *bs, QDict *options, int flags, E
     }
     bs->total_sectors = client->size / BDRV_SECTOR_SIZE;
     //client->aio_context = bdrv_get_aio_context(bs);
-    qdict_del(options, "use_rdma");
+    qdict_del(options, "use-rdma");
-    qdict_del(options, "rdma_mtu");
+    qdict_del(options, "rdma-mtu");
-    qdict_del(options, "rdma_gid_index");
+    qdict_del(options, "rdma-gid-index");
-    qdict_del(options, "rdma_port_num");
+    qdict_del(options, "rdma-port-num");
-    qdict_del(options, "rdma_device");
+    qdict_del(options, "rdma-device");
-    qdict_del(options, "config_path");
+    qdict_del(options, "config-path");
-    qdict_del(options, "etcd_host");
+    qdict_del(options, "etcd-host");
-    qdict_del(options, "etcd_prefix");
+    qdict_del(options, "etcd-prefix");
     qdict_del(options, "image");
     qdict_del(options, "inode");
     qdict_del(options, "pool");
@@ -515,9 +518,9 @@ static QEMUOptionParameter vitastor_create_opts[] = {
 static const char *vitastor_strong_runtime_opts[] = {
     "inode",
     "pool",
-    "config_path",
+    "config-path",
-    "etcd_host",
+    "etcd-host",
-    "etcd_prefix",
+    "etcd-prefix",
 
     NULL
 };

src/stub_osd.cpp

@@ -37,6 +37,7 @@
 
 #include <stdexcept>
 
+#include "mmap_manager.h"
 #include "rw_blocking.h"
 #include "osd_ops.h"
 
@@ -115,6 +116,12 @@ int bind_stub(const char *bind_address, int bind_port)
 
 void run_stub(int peer_fd)
 {
+    mmap_manager_t mm;
+    int pipe_fd[2];
+    if (pipe(pipe_fd) < 0)
+    {
+        throw std::runtime_error(std::string("pipe: ") + strerror(errno));
+    }
     osd_any_op_t op;
     osd_any_reply_t reply;
     void *buf = NULL;
@@ -136,11 +143,39 @@ void run_stub(int peer_fd)
         if (op.hdr.opcode == OSD_OP_SEC_READ)
         {
             reply.hdr.retval = op.sec_rw.len;
-            buf = malloc(op.sec_rw.len);
+            //buf = malloc(op.sec_rw.len);
+            buf = mm.alloc(op.sec_rw.len);
             r = write_blocking(peer_fd, reply.buf, OSD_PACKET_SIZE);
             if (r == OSD_PACKET_SIZE)
-                r = write_blocking(peer_fd, &buf, op.sec_rw.len);
+            {
-            free(buf);
+                size_t offset = 0;
+                while (offset < op.sec_rw.len)
+                {
+                    iovec iov = { .iov_base = buf+offset, .iov_len = op.sec_rw.len-offset };
+                    int vmspliced = vmsplice(pipe_fd[1], &iov, 1, SPLICE_F_GIFT);
+                    if (vmspliced < 0)
+                    {
+                        throw std::runtime_error(std::string("vmsplice: ")+strerror(errno));
+                    }
+                    int spliced = 0;
+                    while (spliced < vmspliced)
+                    {
+                        int r2 = splice(pipe_fd[0], NULL, peer_fd, NULL, vmspliced-spliced, SPLICE_F_MOVE);
+                        if (r2 < 0)
+                        {
+                            if (errno != EAGAIN)
+                                throw std::runtime_error(std::string("splice: ")+strerror(errno));
+                        }
+                        else
+                            spliced += r2;
+                    }
+                    offset += vmspliced;
+                }
+                r = offset;
+                //r = write_blocking(peer_fd, &buf, op.sec_rw.len);
+            }
+            mm.free(buf, op.sec_rw.len);
+            buf = NULL;
             if (r < op.sec_rw.len)
                 break;
         }
@@ -170,5 +205,6 @@ void run_stub(int peer_fd)
             break;
         }
     }
-    free(buf);
+    close(pipe_fd[0]);
+    close(pipe_fd[1]);
 }