block: add the zeroinit block driver filter

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-$(CONFIG_VHDX) += vhdx.o vhdx-endian.o vhdx-log.o
 block-obj-y += quorum.o
+block-obj-y += zeroinit.o
 block-obj-y += parallels.o blkdebug.o blkverify.o blkreplay.o
 block-obj-y += block-backend.o snapshot.o qapi.o
 block-obj-$(CONFIG_WIN32) += raw-win32.o win32-aio.o

block/zeroinit.c

@@ -0,0 +1,220 @@
+/*
+ * Filter to fake a zero-initialized block device.
+ *
+ * Copyright (c) 2016 Wolfgang Bumiller <w.bumiller@proxmox.com>
+ * Copyright (c) 2016 Proxmox Server Solutions GmbH
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "block/block_int.h"
+#include "qapi/qmp/qdict.h"
+#include "qapi/qmp/qstring.h"
+#include "qemu/cutils.h"
+
+typedef struct {
+    bool has_zero_init;
+    int64_t extents;
+} BDRVZeroinitState;
+
+/* Valid blkverify filenames look like blkverify:path/to/raw_image:path/to/image */
+static void zeroinit_parse_filename(const char *filename, QDict *options,
+                                     Error **errp)
+{
+    QString *raw_path;
+
+    /* Parse the blkverify: prefix */
+    if (!strstart(filename, "zeroinit:", &filename)) {
+        /* There was no prefix; therefore, all options have to be already
+           present in the QDict (except for the filename) */
+        return;
+    }
+
+    raw_path = qstring_from_str(filename);
+    qdict_put(options, "x-next", raw_path);
+}
+
+static QemuOptsList runtime_opts = {
+    .name = "zeroinit",
+    .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
+    .desc = {
+        {
+            .name = "x-next",
+            .type = QEMU_OPT_STRING,
+            .help = "[internal use only, will be removed]",
+        },
+        {
+            .name = "x-zeroinit",
+            .type = QEMU_OPT_BOOL,
+            .help = "set has_initialized_zero flag",
+        },
+        { /* end of list */ }
+    },
+};
+
+static int zeroinit_open(BlockDriverState *bs, QDict *options, int flags,
+                          Error **errp)
+{
+    BDRVZeroinitState *s = bs->opaque;
+    QemuOpts *opts;
+    Error *local_err = NULL;
+    int ret;
+
+    s->extents = 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;
+    }
+
+    /* Open the raw file */
+    bs->file = bdrv_open_child(qemu_opt_get(opts, "x-next"), options, "next",
+                               bs, &child_file, false, &local_err);
+    if (local_err) {
+        ret = -EINVAL;
+        error_propagate(errp, local_err);
+        goto fail;
+    }
+
+    /* set the options */
+    s->has_zero_init = qemu_opt_get_bool(opts, "x-zeroinit", true);
+
+    ret = 0;
+fail:
+    if (ret < 0) {
+        bdrv_unref_child(bs, bs->file);
+    }
+    qemu_opts_del(opts);
+    return ret;
+}
+
+static void zeroinit_close(BlockDriverState *bs)
+{
+    BDRVZeroinitState *s = bs->opaque;
+    (void)s;
+}
+
+static int64_t zeroinit_getlength(BlockDriverState *bs)
+{
+    return bdrv_getlength(bs->file->bs);
+}
+
+static BlockAIOCB *zeroinit_aio_readv(BlockDriverState *bs,
+        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
+        BlockCompletionFunc *cb, void *opaque)
+{
+    return bdrv_aio_readv(bs->file, sector_num, qiov, nb_sectors,
+                          cb, opaque);
+}
+
+static int coroutine_fn zeroinit_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
+                                                 int count, BdrvRequestFlags flags)
+{
+    BDRVZeroinitState *s = bs->opaque;
+    if (offset >= s->extents)
+        return 0;
+    return bdrv_pwrite_zeroes(bs->file, offset, count, flags);
+}
+
+static BlockAIOCB *zeroinit_aio_writev(BlockDriverState *bs,
+        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
+        BlockCompletionFunc *cb, void *opaque)
+{
+    BDRVZeroinitState *s = bs->opaque;
+    int64_t extents = (sector_num << BDRV_SECTOR_BITS) + ((nb_sectors + 1) << BDRV_SECTOR_BITS);
+    if (extents > s->extents)
+        s->extents = extents;
+    return bdrv_aio_writev(bs->file, sector_num, qiov, nb_sectors,
+                           cb, opaque);
+}
+
+static BlockAIOCB *zeroinit_aio_flush(BlockDriverState *bs,
+                                       BlockCompletionFunc *cb,
+                                       void *opaque)
+{
+    return bdrv_aio_flush(bs->file->bs, cb, opaque);
+}
+
+static bool zeroinit_recurse_is_first_non_filter(BlockDriverState *bs,
+                                                  BlockDriverState *candidate)
+{
+    return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
+}
+
+static coroutine_fn int zeroinit_co_flush(BlockDriverState *bs)
+{
+    return bdrv_co_flush(bs->file->bs);
+}
+
+static int zeroinit_has_zero_init(BlockDriverState *bs)
+{
+    BDRVZeroinitState *s = bs->opaque;
+    return s->has_zero_init;
+}
+
+static int64_t coroutine_fn zeroinit_co_get_block_status(BlockDriverState *bs,
+                                                         int64_t sector_num,
+                                                         int nb_sectors, int *pnum,
+                                                         BlockDriverState **file)
+{
+    return bdrv_get_block_status(bs->file->bs, sector_num, nb_sectors, pnum, file);
+}
+
+static coroutine_fn BlockAIOCB *zeroinit_aio_pdiscard(BlockDriverState *bs,
+                                                     int64_t offset, int count,
+                                                     BlockCompletionFunc *cb, void *opaque)
+{
+    return bdrv_aio_pdiscard(bs->file->bs, offset, count, cb, opaque);
+}
+
+static int zeroinit_truncate(BlockDriverState *bs, int64_t offset)
+{
+    return bdrv_truncate(bs->file->bs, offset);
+}
+
+static int zeroinit_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
+{
+    return bdrv_get_info(bs->file->bs, bdi);
+}
+
+static BlockDriver bdrv_zeroinit = {
+    .format_name                      = "zeroinit",
+    .protocol_name                    = "zeroinit",
+    .instance_size                    = sizeof(BDRVZeroinitState),
+
+    .bdrv_parse_filename              = zeroinit_parse_filename,
+    .bdrv_file_open                   = zeroinit_open,
+    .bdrv_close                       = zeroinit_close,
+    .bdrv_getlength                   = zeroinit_getlength,
+    .bdrv_co_flush_to_disk            = zeroinit_co_flush,
+
+    .bdrv_co_pwrite_zeroes            = zeroinit_co_pwrite_zeroes,
+    .bdrv_aio_writev                  = zeroinit_aio_writev,
+    .bdrv_aio_readv                   = zeroinit_aio_readv,
+    .bdrv_aio_flush                   = zeroinit_aio_flush,
+
+    .is_filter                        = true,
+    .bdrv_recurse_is_first_non_filter = zeroinit_recurse_is_first_non_filter,
+
+    .bdrv_has_zero_init = zeroinit_has_zero_init,
+
+    .bdrv_co_get_block_status = zeroinit_co_get_block_status,
+
+    .bdrv_aio_pdiscard = zeroinit_aio_pdiscard,
+
+    .bdrv_truncate = zeroinit_truncate,
+    .bdrv_get_info = zeroinit_get_info,
+};
+
+static void bdrv_zeroinit_init(void)
+{
+    bdrv_register(&bdrv_zeroinit);
+}
+
+block_init(bdrv_zeroinit_init);