[Qemu-block] [PATCH RFC 01/22] block/pcache: empty pcache driver filter

[Pavel Butsykin]

The basic version of pcache driver for easy preparation of a patch set.

Signed-off-by: Pavel Butsykin <address@hidden>
---
 block/Makefile.objs |   1 +
 block/pcache.c      | 156 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 157 insertions(+)
 create mode 100644 block/pcache.c

diff --git a/block/Makefile.objs b/block/Makefile.objs
index 2593a2f..7c588ac 100644
--- a/block/Makefile.objs
+++ b/block/Makefile.objs
@@ -4,6 +4,7 @@ block-obj-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o 
qed-cluster.o
 block-obj-y += qed-check.o
 block-obj-$(CONFIG_VHDX) += vhdx.o vhdx-endian.o vhdx-log.o
 block-obj-y += quorum.o
+block-obj-y += pcache.o
 block-obj-y += parallels.o blkdebug.o blkverify.o blkreplay.o
 block-obj-y += block-backend.o snapshot.o qapi.o
 block-obj-$(CONFIG_WIN32) += raw-win32.o win32-aio.o
diff --git a/block/pcache.c b/block/pcache.c
new file mode 100644
index 0000000..770bbc0
--- /dev/null
+++ b/block/pcache.c
@@ -0,0 +1,156 @@
+/*
+ * Prefetch cache driver filter
+ *
+ * Copyright (c) 2016 Pavel Butsykin <address@hidden>
+ *
+ * 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.
+ */
+
+#include "qemu/osdep.h"
+#include "block/block_int.h"
+#include "qapi/error.h"
+#include "qapi/qmp/qstring.h"
+
+
+static const AIOCBInfo pcache_aiocb_info = {
+    .aiocb_size = sizeof(BlockAIOCB),
+};
+
+static QemuOptsList runtime_opts = {
+    .name = "pcache",
+    .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
+    .desc = {
+        {
+            .name = "x-image",
+            .type = QEMU_OPT_STRING,
+            .help = "[internal use only, will be removed]",
+        },
+        { /* end of list */ }
+    },
+};
+
+static void pcache_aio_cb(void *opaque, int ret)
+{
+
+    BlockAIOCB *acb = opaque;
+
+    acb->cb(acb->opaque, ret);
+
+    qemu_aio_unref(acb);
+}
+
+static BlockAIOCB *pcache_aio_readv(BlockDriverState *bs,
+                                    int64_t sector_num,
+                                    QEMUIOVector *qiov,
+                                    int nb_sectors,
+                                    BlockCompletionFunc *cb,
+                                    void *opaque)
+{
+    BlockAIOCB *acb = qemu_aio_get(&pcache_aiocb_info, bs, cb, opaque);
+
+    bdrv_aio_readv(bs->file, sector_num, qiov, nb_sectors,
+                   pcache_aio_cb, acb);
+    return acb;
+}
+
+static BlockAIOCB *pcache_aio_writev(BlockDriverState *bs,
+                                     int64_t sector_num,
+                                     QEMUIOVector *qiov,
+                                     int nb_sectors,
+                                     BlockCompletionFunc *cb,
+                                     void *opaque)
+{
+    BlockAIOCB *acb = qemu_aio_get(&pcache_aiocb_info, bs, cb, opaque);
+
+    bdrv_aio_writev(bs->file, sector_num, qiov, nb_sectors,
+                    pcache_aio_cb, acb);
+    return acb;
+}
+
+static int pcache_file_open(BlockDriverState *bs, QDict *options, int flags,
+                            Error **errp)
+{
+    QemuOpts *opts;
+    Error *local_err = NULL;
+    int ret = 0;
+
+    opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
+    qemu_opts_absorb_qdict(opts, options, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        ret = -EINVAL;
+        goto fail;
+    }
+
+    assert(bs->file == NULL);
+    bs->file = bdrv_open_child(qemu_opt_get(opts, "x-image"), options,
+                               "image", bs, &child_format, false, &local_err);
+    if (local_err) {
+        ret = -EINVAL;
+        error_propagate(errp, local_err);
+    }
+fail:
+    qemu_opts_del(opts);
+    return ret;
+}
+
+static void pcache_close(BlockDriverState *bs)
+{
+}
+
+static void pcache_parse_filename(const char *filename, QDict *options,
+                                  Error **errp)
+{
+    qdict_put(options, "x-image", qstring_from_str(filename));
+}
+
+static int64_t pcache_getlength(BlockDriverState *bs)
+{
+    return bdrv_getlength(bs->file->bs);
+}
+
+static bool pcache_recurse_is_first_non_filter(BlockDriverState *bs,
+                                               BlockDriverState *candidate)
+{
+    return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
+}
+
+static BlockDriver bdrv_pcache = {
+    .format_name                        = "pcache",
+    .protocol_name                      = "pcache",
+    .instance_size                      = 0,
+
+    .bdrv_parse_filename                = pcache_parse_filename,
+    .bdrv_file_open                     = pcache_file_open,
+    .bdrv_close                         = pcache_close,
+    .bdrv_getlength                     = pcache_getlength,
+
+    .bdrv_aio_readv                     = pcache_aio_readv,
+    .bdrv_aio_writev                    = pcache_aio_writev,
+
+    .is_filter                          = true,
+    .bdrv_recurse_is_first_non_filter   = pcache_recurse_is_first_non_filter,
+};
+
+static void bdrv_cache_init(void)
+{
+    bdrv_register(&bdrv_pcache);
+}
+
+block_init(bdrv_cache_init);
-- 
2.8.3