Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

Pull request

v2:
 * Drop merge failure from a previous pull request that broke virtio-blk on ARM
   guests
 * Add Parallels XML patch series

# gpg: Signature made Mon 22 Jan 2018 16:00:40 GMT
# gpg:                using RSA key 0x9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request:
  block/parallels: add backing support to readv/writev
  block/parallels: replace some magic numbers
  block/parallels: move some structures into header
  configure: add dependency
  docs/interop/prl-xml: description of Parallels Disk format
  block: add block_set_io_throttle virtio-blk-pci QMP example

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

7 files changed, 342 insertions, 60 deletions

diff --git a/block/Makefile.objs b/block/Makefile.objs
index 6eaf78a046..a73387f1bf 100644
--- a/block/Makefile.objs
+++ b/block/Makefile.objs
@@ -47,3 +47,5 @@ block-obj-$(if $(CONFIG_BZIP2),m,n) += dmg-bz2.o
 dmg-bz2.o-libs     := $(BZIP2_LIBS)
 qcow.o-libs        := -lz
 linux-aio.o-libs   := -laio
+parallels.o-cflags := $(LIBXML2_CFLAGS)
+parallels.o-libs   := $(LIBXML2_LIBS)
diff --git a/block/parallels.c b/block/parallels.c
index 9545761f49..d3802085e3 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -36,6 +36,7 @@
 #include "qemu/bswap.h"
 #include "qemu/bitmap.h"
 #include "migration/blocker.h"
+#include "parallels.h"
 
 /**************************************************************/
 
@@ -45,30 +46,6 @@
 #define HEADER_INUSE_MAGIC  (0x746F6E59)
 #define MAX_PARALLELS_IMAGE_FACTOR (1ull << 32)
 
-#define DEFAULT_CLUSTER_SIZE 1048576        /* 1 MiB */
-
-
-// always little-endian
-typedef struct ParallelsHeader {
-    char magic[16]; // "WithoutFreeSpace"
-    uint32_t version;
-    uint32_t heads;
-    uint32_t cylinders;
-    uint32_t tracks;
-    uint32_t bat_entries;
-    uint64_t nb_sectors;
-    uint32_t inuse;
-    uint32_t data_off;
-    char padding[12];
-} QEMU_PACKED ParallelsHeader;
-
-
-typedef enum ParallelsPreallocMode {
-    PRL_PREALLOC_MODE_FALLOCATE = 0,
-    PRL_PREALLOC_MODE_TRUNCATE = 1,
-    PRL_PREALLOC_MODE__MAX = 2,
-} ParallelsPreallocMode;
-
 static QEnumLookup prealloc_mode_lookup = {
     .array = (const char *const[]) {
         "falloc",
@@ -77,34 +54,6 @@ static QEnumLookup prealloc_mode_lookup = {
     .size = PRL_PREALLOC_MODE__MAX
 };
 
-typedef struct BDRVParallelsState {
-    /** Locking is conservative, the lock protects
-     *   - image file extending (truncate, fallocate)
-     *   - any access to block allocation table
-     */
-    CoMutex lock;
-
-    ParallelsHeader *header;
-    uint32_t header_size;
-    bool header_unclean;
-
-    unsigned long *bat_dirty_bmap;
-    unsigned int  bat_dirty_block;
-
-    uint32_t *bat_bitmap;
-    unsigned int bat_size;
-
-    int64_t  data_end;
-    uint64_t prealloc_size;
-    ParallelsPreallocMode prealloc_mode;
-
-    unsigned int tracks;
-
-    unsigned int off_multiplier;
-    Error *migration_blocker;
-} BDRVParallelsState;
-
-
 #define PARALLELS_OPT_PREALLOC_MODE     "prealloc-mode"
 #define PARALLELS_OPT_PREALLOC_SIZE     "prealloc-size"
 
@@ -193,6 +142,7 @@ static int64_t block_status(BDRVParallelsState *s, int64_t sector_num,
 static int64_t allocate_clusters(BlockDriverState *bs, int64_t sector_num,
                                  int nb_sectors, int *pnum)
 {
+    int ret;
     BDRVParallelsState *s = bs->opaque;
     int64_t pos, space, idx, to_allocate, i, len;
 
@@ -221,7 +171,6 @@ static int64_t allocate_clusters(BlockDriverState *bs, int64_t sector_num,
         return len;
     }
     if (s->data_end + space > (len >> BDRV_SECTOR_BITS)) {
-        int ret;
         space += s->prealloc_size;
         if (s->prealloc_mode == PRL_PREALLOC_MODE_FALLOCATE) {
             ret = bdrv_pwrite_zeroes(bs->file,
@@ -237,6 +186,37 @@ static int64_t allocate_clusters(BlockDriverState *bs, int64_t sector_num,
         }
     }
 
+    /* Try to read from backing to fill empty clusters
+     * FIXME: 1. previous write_zeroes may be redundant
+     *        2. most of data we read from backing will be rewritten by
+     *           parallels_co_writev. On aligned-to-cluster write we do not need
+     *           this read at all.
+     *        3. it would be good to combine write of data from backing and new
+     *           data into one write call */
+    if (bs->backing) {
+        int64_t nb_cow_sectors = to_allocate * s->tracks;
+        int64_t nb_cow_bytes = nb_cow_sectors << BDRV_SECTOR_BITS;
+        QEMUIOVector qiov;
+        struct iovec iov = {
+            .iov_len = nb_cow_bytes,
+            .iov_base = qemu_blockalign(bs, nb_cow_bytes)
+        };
+        qemu_iovec_init_external(&qiov, &iov, 1);
+
+        ret = bdrv_co_readv(bs->backing, idx * s->tracks, nb_cow_sectors,
+                            &qiov);
+        if (ret < 0) {
+            qemu_vfree(iov.iov_base);
+            return ret;
+        }
+
+        ret = bdrv_co_writev(bs->file, s->data_end, nb_cow_sectors, &qiov);
+        qemu_vfree(iov.iov_base);
+        if (ret < 0) {
+            return ret;
+        }
+    }
+
     for (i = 0; i < to_allocate; i++) {
         s->bat_bitmap[idx + i] = cpu_to_le32(s->data_end / s->off_multiplier);
         s->data_end += s->tracks;
@@ -360,12 +340,19 @@ static coroutine_fn int parallels_co_readv(BlockDriverState *bs,
 
         nbytes = n << BDRV_SECTOR_BITS;
 
+        qemu_iovec_reset(&hd_qiov);
+        qemu_iovec_concat(&hd_qiov, qiov, bytes_done, nbytes);
+
         if (position < 0) {
-            qemu_iovec_memset(qiov, bytes_done, 0, nbytes);
+            if (bs->backing) {
+                ret = bdrv_co_readv(bs->backing, sector_num, n, &hd_qiov);
+                if (ret < 0) {
+                    break;
+                }
+            } else {
+                qemu_iovec_memset(&hd_qiov, 0, 0, nbytes);
+            }
         } else {
-            qemu_iovec_reset(&hd_qiov);
-            qemu_iovec_concat(&hd_qiov, qiov, bytes_done, nbytes);
-
             ret = bdrv_co_readv(bs->file, position, n, &hd_qiov);
             if (ret < 0) {
                 break;
@@ -527,8 +514,9 @@ static int parallels_create(const char *filename, QemuOpts *opts, Error **errp)
     memcpy(header.magic, HEADER_MAGIC2, sizeof(header.magic));
     header.version = cpu_to_le32(HEADER_VERSION);
     /* don't care much about geometry, it is not used on image level */
-    header.heads = cpu_to_le32(16);
-    header.cylinders = cpu_to_le32(total_size / BDRV_SECTOR_SIZE / 16 / 32);
+    header.heads = cpu_to_le32(HEADS_NUMBER);
+    header.cylinders = cpu_to_le32(total_size / BDRV_SECTOR_SIZE
+                                   / HEADS_NUMBER / SEC_IN_CYL);
     header.tracks = cpu_to_le32(cl_size >> BDRV_SECTOR_BITS);
     header.bat_entries = cpu_to_le32(bat_entries);
     header.nb_sectors = cpu_to_le64(DIV_ROUND_UP(total_size, BDRV_SECTOR_SIZE));
@@ -798,7 +786,7 @@ static BlockDriver bdrv_parallels = {
     .bdrv_co_flush_to_os      = parallels_co_flush_to_os,
     .bdrv_co_readv  = parallels_co_readv,
     .bdrv_co_writev = parallels_co_writev,
-
+    .supports_backing = true,
     .bdrv_create    = parallels_create,
     .bdrv_check     = parallels_check,
     .create_opts    = &parallels_create_opts,
diff --git a/block/parallels.h b/block/parallels.h
new file mode 100644
index 0000000000..4b044079ef
--- /dev/null
+++ b/block/parallels.h
@@ -0,0 +1,88 @@
+/*
+* Block driver for Parallels disk image format
+*
+* Copyright (c) 2015-2017 Virtuozzo, Inc.
+* Authors:
+*         2016-2017 Klim S. Kireev <klim.kireev@virtuozzo.com>
+*         2015 Denis V. Lunev <den@openvz.org>
+*
+* This code was originally based on comparing different disk images created
+* by Parallels. Currently it is based on opened OpenVZ sources
+* available at
+*     https://github.com/OpenVZ/ploop
+*
+* Permission is hereby granted, free of charge, to any person obtaining a copy
+* of this software and associated documentation files (the "Software"), to deal
+* in the Software without restriction, including without limitation the rights
+* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+* copies of the Software, and to permit persons to whom the Software is
+* furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included in
+* all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+* THE SOFTWARE.
+*/
+#ifndef BLOCK_PARALLELS_H
+#define BLOCK_PARALLELS_H
+#include "qemu/coroutine.h"
+#include "qemu/typedefs.h"
+
+#define HEADS_NUMBER 16
+#define SEC_IN_CYL 32
+#define DEFAULT_CLUSTER_SIZE 1048576        /* 1 MiB */
+
+/* always little-endian */
+typedef struct ParallelsHeader {
+    char magic[16]; /* "WithoutFreeSpace" */
+    uint32_t version;
+    uint32_t heads;
+    uint32_t cylinders;
+    uint32_t tracks;
+    uint32_t bat_entries;
+    uint64_t nb_sectors;
+    uint32_t inuse;
+    uint32_t data_off;
+    char padding[12];
+} QEMU_PACKED ParallelsHeader;
+
+typedef enum ParallelsPreallocMode {
+    PRL_PREALLOC_MODE_FALLOCATE = 0,
+    PRL_PREALLOC_MODE_TRUNCATE = 1,
+    PRL_PREALLOC_MODE__MAX = 2,
+} ParallelsPreallocMode;
+
+typedef struct BDRVParallelsState {
+    /** Locking is conservative, the lock protects
+     *   - image file extending (truncate, fallocate)
+     *   - any access to block allocation table
+     */
+    CoMutex lock;
+
+    ParallelsHeader *header;
+    uint32_t header_size;
+    bool header_unclean;
+
+    unsigned long *bat_dirty_bmap;
+    unsigned int  bat_dirty_block;
+
+    uint32_t *bat_bitmap;
+    unsigned int bat_size;
+
+    int64_t  data_end;
+    uint64_t prealloc_size;
+    ParallelsPreallocMode prealloc_mode;
+
+    unsigned int tracks;
+
+    unsigned int off_multiplier;
+    Error *migration_blocker;
+} BDRVParallelsState;
+
+#endif
diff --git a/configure b/configure
index 6d8c996c62..044c6fafe2 100755
--- a/configure
+++ b/configure
@@ -435,6 +435,7 @@ tcmalloc="no"
 jemalloc="no"
 replication="yes"
 vxhs=""
+libxml2=""
 
 supported_cpu="no"
 supported_os="no"
@@ -1298,6 +1299,10 @@ for opt do
   ;;
   --enable-numa) numa="yes"
   ;;
+  --disable-libxml2) libxml2="no"
+  ;;
+  --enable-libxml2) libxml2="yes"
+  ;;
   --disable-tcmalloc) tcmalloc="no"
   ;;
   --enable-tcmalloc) tcmalloc="yes"
@@ -1573,6 +1578,7 @@ disabled with --disable-FEATURE, default is enabled if available:
   tpm             TPM support
   libssh2         ssh block device support
   numa            libnuma support
+  libxml2         for Parallels image format
   tcmalloc        tcmalloc support
   jemalloc        jemalloc support
   replication     replication support
@@ -3748,6 +3754,20 @@ EOF
   fi
 fi
 
+##########################################
+# libxml2 probe
+if test "$libxml2" != "no" ; then
+    if $pkg_config --exists libxml-2.0; then
+        libxml2="yes"
+        libxml2_cflags=$($pkg_config --cflags libxml-2.0)
+        libxml2_libs=$($pkg_config --libs libxml-2.0)
+    else
+        if test "$libxml2" = "yes"; then
+            feature_not_found "libxml2" "Install libxml2 devel"
+        fi
+        libxml2="no"
+    fi
+fi
 
 ##########################################
 # glusterfs probe
@@ -5630,6 +5650,7 @@ echo "lzo support       $lzo"
 echo "snappy support    $snappy"
 echo "bzip2 support     $bzip2"
 echo "NUMA host support $numa"
+echo "libxml2           $libxml2"
 echo "tcmalloc support  $tcmalloc"
 echo "jemalloc support  $jemalloc"
 echo "avx2 optimization $avx2_opt"
@@ -6299,6 +6320,12 @@ if test "$have_rtnetlink" = "yes" ; then
   echo "CONFIG_RTNETLINK=y" >> $config_host_mak
 fi
 
+if test "$libxml2" = "yes" ; then
+  echo "CONFIG_LIBXML2=y" >> $config_host_mak
+  echo "LIBXML2_CFLAGS=$libxml2_cflags" >> $config_host_mak
+  echo "LIBXML2_LIBS=$libxml2_libs" >> $config_host_mak
+fi
+
 if test "$replication" = "yes" ; then
   echo "CONFIG_REPLICATION=y" >> $config_host_mak
 fi
diff --git a/docs/interop/prl-xml.txt b/docs/interop/prl-xml.txt
new file mode 100644
index 0000000000..7031f8752c
--- /dev/null
+++ b/docs/interop/prl-xml.txt
@@ -0,0 +1,158 @@
+= License =
+
+Copyright (c) 2015-2017, Virtuozzo, Inc.
+Authors:
+        2015 Denis Lunev <den@openvz.org>
+        2015 Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
+        2016-2017 Klim Kireev <klim.kireev@virtuozzo.com>
+        2016-2017 Edgar Kaziakhmedov <edgar.kaziakhmedov@virtuozzo.com>
+
+This work is licensed under the terms of the GNU GPL, version 2 or later.
+See the COPYING file in the top-level directory.
+
+This specification contains minimal information about Parallels Disk Format,
+which is enough to proper work with QEMU. Nevertheless, Parallels Cloud Server
+and Parallels Desktop are able to add some unspecified nodes to xml and use
+them, but they are for internal work and don't affect functionality. Also it
+uses auxiliary xml "Snapshot.xml", which allows to store optional snapshot
+information, but it doesn't influence open/read/write functionality. QEMU and
+other software should not use fields not covered in this document and
+Snapshot.xml file and must leave them as is.
+
+= Parallels Disk Format =
+
+Parallels disk consists of two parts: the set of snapshots and the disk
+descriptor file, which stores information about all files and snapshots.
+
+== Definitions ==
+    Snapshot       a record of the contents captured at a particular time,
+                   capable of storing current state. A snapshot has UUID and
+                   parent UUID.
+
+ Snapshot image    an overlay representing the difference between this
+                   snapshot and some earlier snapshot.
+
+    Overlay        an image storing the different sectors between two captured
+                   states.
+
+   Root image      snapshot image with no parent, the root of snapshot tree.
+
+    Storage        the backing storage for a subset of the virtual disk. When
+                   there is more than one storage in a Parallels disk then that
+                   is referred to as a split image. In this case every storage
+                   covers specific address space area of the disk and has its
+                   particular root image. Split images are not considered here
+                   and are not supported. Each storage consists of disk
+                   parameters and a list of images. The list of images always
+                   contains a root image and may also contain overlays. The
+                   root image can be an expandable Parallels image file or
+                   plain. Overlays must be expandable.
+
+  Description      DiskDescriptor.xml stores information about disk parameters,
+     file          snapshots, storages.
+
+     Top           The overlay between actual state and some previous snapshot.
+   Snapshot        It is not a snapshot in the classical sense because it
+                   serves as the active image that the guest writes to.
+
+    Sector         a 512-byte data chunk.
+
+== Description file ==
+All information is placed in a single XML element Parallels_disk_image.
+The element has only one attribute "Version", that must be 1.0.
+Schema of DiskDescriptor.xml:
+
+<Parallels_disk_image Version="1.0">
+    <Disk_Parameters>
+        ...
+    </Disk_Parameters>
+    <StorageData>
+        ...
+    </StorageData>
+    <Snapshots>
+        ...
+    </Snapshots>
+</Parallels_disk_image>
+
+== Disk_Parameters element ==
+The Disk_Parameters element describes the physical layout of the virtual disk
+and some general settings.
+
+The Disk_Parameters element MUST contain the following child elements:
+    * Disk_size - number of sectors in the disk,
+                  desired size of the disk.
+    * Cylinders - number of the disk cylinders.
+    * Heads     - number of the disk heads.
+    * Sectors   - number of the disk sectors per cylinder
+                  (sector size is 512 bytes)
+                  Limitation: Product of the Heads, Sectors and Cylinders
+                  values MUST be equal to the value of the Disk_size parameter.
+    * Padding   - must be 0. Parallels Cloud Server and Parallels Desktop may
+                  use padding set to 1, however this case is not covered
+                  by this spec, QEMU and other software should not open
+                  such disks and should not create them.
+
+== StorageData element ==
+This element of the file describes the root image and all snapshot images.
+
+The StorageData element consists of the Storage child element, as shown below:
+<StorageData>
+    <Storage>
+        ...
+    </Storage>
+</StorageData>
+
+A Storage element has following child elements:
+    * Start     - start sector of the storage, in case of non split storage
+                  equals to 0.
+    * End       - number of sector following the last sector, in case of non
+                  split storage equals to Disk_size.
+    * Blocksize - storage cluster size, number of sectors per one cluster.
+                  Cluster size for each "Compressed" (see below) image in
+                  parallels disk must be equal to this field. Note: cluster
+                  size for Parallels Expandable Image is in 'tracks' field of
+                  its header (see docs/interop/parallels.txt).
+    * Several Image child elements.
+
+Each Image element has following child elements:
+    * GUID - image identifier, UUID in curly brackets.
+             For instance, {12345678-9abc-def1-2345-6789abcdef12}.
+             The GUID is used by the Snapshots element to reference images
+             (see below)
+    * Type - image type of the element. It can be:
+             "Plain" for raw files.
+             "Compressed" for expanding disks.
+    * File - path to image file. Path can be relative to DiskDecriptor.xml or
+             absolute.
+
+== Snapshots element ==
+The Snapshots element describes the snapshot relations with the snapshot tree.
+
+The element contains the set of Shot child elements, as shown below:
+<Snapshots>
+    <TopGUID> ... </TopGUID> /* Optional child element */
+    <Shot>
+        ...
+    </Shot>
+    <Shot>
+        ...
+    </Shot>
+    ...
+</Snapshots>
+
+Each Shot element contains the following child elements:
+    * GUID       - an image GUID.
+    * ParentGUID - GUID of the image of the parent snapshot.
+
+The software may traverse snapshots from child to parent using <ParentGUID>
+field as reference. ParentGUID of root snapshot is
+{00000000-0000-0000-0000-000000000000}. There should be only one root
+snapshot. Top snapshot could be described via two ways: via TopGUID child
+element of the Snapshots element or via predefined GUID
+{5fbaabe3-6958-40ff-92a7-860e329aab41}. If TopGUID is defined, predefined GUID is
+interpreted as usual GUID. All snapshot images (except Top Snapshot) should be
+opened read-only. There is another predefined GUID,
+BackupID = {704718e1-2314-44c8-9087-d78ed36b0f4e}, which is used by original and
+some third-party software for backup, QEMU and other software may operate with
+images with GUID = BackupID as usual, however, it is not recommended to use this
+GUID for new disks. Top snapshot cannot have this GUID.
diff --git a/qapi/block-core.json b/qapi/block-core.json
index e94a6881b2..4e84cf29db 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1799,6 +1799,24 @@
 # Example:
 #
 # -> { "execute": "block_set_io_throttle",
+#      "arguments": { "id": "virtio-blk-pci0/virtio-backend",
+#                     "bps": 0,
+#                     "bps_rd": 0,
+#                     "bps_wr": 0,
+#                     "iops": 512,
+#                     "iops_rd": 0,
+#                     "iops_wr": 0,
+#                     "bps_max": 0,
+#                     "bps_rd_max": 0,
+#                     "bps_wr_max": 0,
+#                     "iops_max": 0,
+#                     "iops_rd_max": 0,
+#                     "iops_wr_max": 0,
+#                     "bps_max_length": 0,
+#                     "iops_size": 0 } }
+# <- { "return": {} }
+#
+# -> { "execute": "block_set_io_throttle",
 #      "arguments": { "id": "ide0-1-0",
 #                     "bps": 1000000,
 #                     "bps_rd": 0,
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index accba24a31..1b4b812e28 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -265,6 +265,7 @@ our @typeList = (
 	qr{${Ident}_handler_fn},
 	qr{target_(?:u)?long},
 	qr{hwaddr},
+	qr{xml${Ident}},
 );
 
 # This can be modified by sub possible.  Since it can be empty, be careful