From b4442d3284353b0ad54eacbe7e29c8d09dbcf301 Mon Sep 17 00:00:00 2001

From: Max Reitz <mreitz@redhat.com>

Date: Mon, 18 Jun 2018 16:12:04 +0200

Subject: [PATCH 037/268] block: Add COR filter driver

RH-Author: Max Reitz <mreitz@redhat.com>

Message-id: <20180618161212.14444-3-mreitz@redhat.com>

Patchwork-id: 80762

O-Subject: [RHV-7.6 qemu-kvm-rhev PATCH 02/10] block: Add COR filter driver

Bugzilla: 1518738

RH-Acked-by: John Snow <jsnow@redhat.com>

RH-Acked-by: Kevin Wolf <kwolf@redhat.com>

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

This adds a simple copy-on-read filter driver.  It relies on the already

existing COR functionality in the central block layer code, which may be

moved here once we no longer need it there.

Signed-off-by: Max Reitz <mreitz@redhat.com>

Message-id: 20180421132929.21610-2-mreitz@redhat.com

Reviewed-by: Alberto Garcia <berto@igalia.com>

Reviewed-by: Kevin Wolf <kwolf@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>

(cherry picked from commit 6c6f24fd84895d03baa898bbc4324dd4ccc97071)

Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 block/Makefile.objs  |   2 +-

 block/copy-on-read.c | 171 +++++++++++++++++++++++++++++++++++++++++++++++++++

 qapi/block-core.json |   5 +-

 3 files changed, 176 insertions(+), 2 deletions(-)

 create mode 100644 block/copy-on-read.c

diff --git a/block/Makefile.objs b/block/Makefile.objs

index c0693fc..be2cda1 100644

--- a/block/Makefile.objs

+++ b/block/Makefile.objs

@@ -26,7 +26,7 @@ block-obj-y += accounting.o dirty-bitmap.o

 block-obj-y += write-threshold.o

 block-obj-y += backup.o

 block-obj-$(CONFIG_REPLICATION) += replication.o

-block-obj-y += throttle.o

+block-obj-y += throttle.o copy-on-read.o

 block-obj-y += crypto.o

diff --git a/block/copy-on-read.c b/block/copy-on-read.c

new file mode 100644

index 0000000..823ec75

--- /dev/null

+++ b/block/copy-on-read.c

@@ -0,0 +1,171 @@

+/*

+ * Copy-on-read filter block driver

+ *

+ * Copyright (c) 2018 Red Hat, Inc.

+ *

+ * Author:

+ *   Max Reitz <mreitz@redhat.com>

+ *

+ * This program is free software; you can redistribute it and/or

+ * modify it under the terms of the GNU General Public License as

+ * published by the Free Software Foundation; either version 2 or

+ * (at your option) version 3 of the License.

+ *

+ * This program is distributed in the hope that it will be useful,

+ * but WITHOUT ANY WARRANTY; without even the implied warranty of

+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

+ * GNU General Public License for more details.

+ *

+ * You should have received a copy of the GNU General Public License

+ * along with this program; if not, see <http://www.gnu.org/licenses/>.

+ */

+

+#include "qemu/osdep.h"

+#include "block/block_int.h"

+

+

+static int cor_open(BlockDriverState *bs, QDict *options, int flags,

+                    Error **errp)

+{

+    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file, false,

+                               errp);

+    if (!bs->file) {

+        return -EINVAL;

+    }

+

+    bs->supported_write_flags = BDRV_REQ_FUA &

+                                    bs->file->bs->supported_write_flags;

+

+    bs->supported_zero_flags = (BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &

+                                    bs->file->bs->supported_zero_flags;

+

+    return 0;

+}

+

+

+static void cor_close(BlockDriverState *bs)

+{

+}

+

+

+#define PERM_PASSTHROUGH (BLK_PERM_CONSISTENT_READ \

+                          | BLK_PERM_WRITE \

+                          | BLK_PERM_RESIZE)

+#define PERM_UNCHANGED (BLK_PERM_ALL & ~PERM_PASSTHROUGH)

+

+static void cor_child_perm(BlockDriverState *bs, BdrvChild *c,

+                           const BdrvChildRole *role,

+                           BlockReopenQueue *reopen_queue,

+                           uint64_t perm, uint64_t shared,

+                           uint64_t *nperm, uint64_t *nshared)

+{

+    if (c == NULL) {

+        *nperm = (perm & PERM_PASSTHROUGH) | BLK_PERM_WRITE_UNCHANGED;

+        *nshared = (shared & PERM_PASSTHROUGH) | PERM_UNCHANGED;

+        return;

+    }

+

+    *nperm = (perm & PERM_PASSTHROUGH) |

+             (c->perm & PERM_UNCHANGED);

+    *nshared = (shared & PERM_PASSTHROUGH) |

+               (c->shared_perm & PERM_UNCHANGED);

+}

+

+

+static int64_t cor_getlength(BlockDriverState *bs)

+{

+    return bdrv_getlength(bs->file->bs);

+}

+

+

+static int cor_truncate(BlockDriverState *bs, int64_t offset,

+                        PreallocMode prealloc, Error **errp)

+{

+    return bdrv_truncate(bs->file, offset, prealloc, errp);

+}

+

+

+static int coroutine_fn cor_co_preadv(BlockDriverState *bs,

+                                      uint64_t offset, uint64_t bytes,

+                                      QEMUIOVector *qiov, int flags)

+{

+    return bdrv_co_preadv(bs->file, offset, bytes, qiov,

+                          flags | BDRV_REQ_COPY_ON_READ);

+}

+

+

+static int coroutine_fn cor_co_pwritev(BlockDriverState *bs,

+                                       uint64_t offset, uint64_t bytes,

+                                       QEMUIOVector *qiov, int flags)

+{

+

+    return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);

+}

+

+

+static int coroutine_fn cor_co_pwrite_zeroes(BlockDriverState *bs,

+                                             int64_t offset, int bytes,

+                                             BdrvRequestFlags flags)

+{

+    return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);

+}

+

+

+static int coroutine_fn cor_co_pdiscard(BlockDriverState *bs,

+                                        int64_t offset, int bytes)

+{

+    return bdrv_co_pdiscard(bs->file->bs, offset, bytes);

+}

+

+

+static void cor_eject(BlockDriverState *bs, bool eject_flag)

+{

+    bdrv_eject(bs->file->bs, eject_flag);

+}

+

+

+static void cor_lock_medium(BlockDriverState *bs, bool locked)

+{

+    bdrv_lock_medium(bs->file->bs, locked);

+}

+

+

+static bool cor_recurse_is_first_non_filter(BlockDriverState *bs,

+                                            BlockDriverState *candidate)

+{

+    return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);

+}

+

+

+BlockDriver bdrv_copy_on_read = {

+    .format_name                        = "copy-on-read",

+

+    .bdrv_open                          = cor_open,

+    .bdrv_close                         = cor_close,

+    .bdrv_child_perm                    = cor_child_perm,

+

+    .bdrv_getlength                     = cor_getlength,

+    .bdrv_truncate                      = cor_truncate,

+

+    .bdrv_co_preadv                     = cor_co_preadv,

+    .bdrv_co_pwritev                    = cor_co_pwritev,

+    .bdrv_co_pwrite_zeroes              = cor_co_pwrite_zeroes,

+    .bdrv_co_pdiscard                   = cor_co_pdiscard,

+

+    .bdrv_eject                         = cor_eject,

+    .bdrv_lock_medium                   = cor_lock_medium,

+

+    .bdrv_co_block_status               = bdrv_co_block_status_from_file,

+

+    .bdrv_recurse_is_first_non_filter   = cor_recurse_is_first_non_filter,

+

+    .has_variable_length                = true,

+    .is_filter                          = true,

+};

+

+static void bdrv_copy_on_read_init(void)

+{

+    bdrv_register(&bdrv_copy_on_read);

+}

+

+block_init(bdrv_copy_on_read_init);

diff --git a/qapi/block-core.json b/qapi/block-core.json

index 51eafdd..9e4f1ac 100644

--- a/qapi/block-core.json

+++ b/qapi/block-core.json

@@ -2506,11 +2506,12 @@

 # @vxhs: Since 2.10

 # @throttle: Since 2.11

 # @nvme: Since 2.12

+# @copy-on-read: Since 2.13

 #

 # Since: 2.9

 ##

 { 'enum': 'BlockdevDriver',

-  'data': [ 'blkdebug', 'blkverify', 'bochs', 'cloop',

+  'data': [ 'blkdebug', 'blkverify', 'bochs', 'cloop', 'copy-on-read',

             'dmg', 'file', 'ftp', 'ftps', 'gluster', 'host_cdrom',

             'host_device', 'http', 'https', 'iscsi', 'luks', 'nbd', 'nfs',

             'null-aio', 'null-co', 'nvme', 'parallels', 'qcow', 'qcow2', 'qed',

@@ -3541,6 +3542,7 @@

       'blkverify':  'BlockdevOptionsBlkverify',

       'bochs':      'BlockdevOptionsGenericFormat',

       'cloop':      'BlockdevOptionsGenericFormat',

+      'copy-on-read':'BlockdevOptionsGenericFormat',

       'dmg':        'BlockdevOptionsGenericFormat',

       'file':       'BlockdevOptionsFile',

       'ftp':        'BlockdevOptionsCurlFtp',

@@ -4068,6 +4070,7 @@

       'blkverify':      'BlockdevCreateNotSupported',

       'bochs':          'BlockdevCreateNotSupported',

       'cloop':          'BlockdevCreateNotSupported',

+      'copy-on-read':   'BlockdevCreateNotSupported',

       'dmg':            'BlockdevCreateNotSupported',

       'file':           'BlockdevCreateOptionsFile',

       'ftp':            'BlockdevCreateNotSupported',

-- 

1.8.3.1