On Tue, 2019-07-23 at 09:13 +0200, Stefano Garzarella wrote:
> This patch adds the support of preallocation (off/full) for the RBD
> block driver.
> If rbd_writesame() is available and supports zeroed buffers, we use
> it to quickly fill the image when full preallocation is required.
>
> Signed-off-by: Stefano Garzarella <sgarz...@redhat.com>
> ---
> v3:
> - rebased on master
> - filled with zeroed buffer [Max]
> - used rbd_writesame() only when we can disable the discard of zeroed
> buffers
> - added 'since: 4.2' in qapi/block-core.json [Max]
> - used buffer as large as the "stripe unit"
> ---
> block/rbd.c | 202 ++++++++++++++++++++++++++++++++++++++++---
> qapi/block-core.json | 5 +-
> 2 files changed, 192 insertions(+), 15 deletions(-)
>
> diff --git a/block/rbd.c b/block/rbd.c
> index 59757b3120..d923a5a26c 100644
> --- a/block/rbd.c
> +++ b/block/rbd.c
> @@ -64,6 +64,7 @@
> #define OBJ_MAX_SIZE (1UL << OBJ_DEFAULT_OBJ_ORDER)
>
> #define RBD_MAX_SNAPS 100
> +#define RBD_DEFAULT_CONCURRENT_OPS 10
>
> /* The LIBRBD_SUPPORTS_IOVEC is defined in librbd.h */
> #ifdef LIBRBD_SUPPORTS_IOVEC
> @@ -104,6 +105,7 @@ typedef struct BDRVRBDState {
> char *image_name;
> char *snap;
> uint64_t image_size;
> + bool ws_zero_supported; /* rbd_writesame() supports zeroed buffers */
> } BDRVRBDState;
>
> static int qemu_rbd_connect(rados_t *cluster, rados_ioctx_t *io_ctx,
> @@ -333,6 +335,155 @@ static void qemu_rbd_memset(RADOSCB *rcb, int64_t offs)
> }
> }
>
> +static int qemu_rbd_get_max_concurrent_ops(rados_t cluster)
> +{
> + char buf[16];
> + int ret, max_concurrent_ops;
> +
> + ret = rados_conf_get(cluster, "rbd_concurrent_management_ops", buf,
> + sizeof(buf));
> + if (ret < 0) {
> + return RBD_DEFAULT_CONCURRENT_OPS;
> + }
> +
> + ret = qemu_strtoi(buf, NULL, 10, &max_concurrent_ops);
> + if (ret < 0) {
> + return RBD_DEFAULT_CONCURRENT_OPS;
> + }
> +
> + return max_concurrent_ops;
> +}
> +
> +static int qemu_rbd_do_truncate(rados_t cluster, rbd_image_t image,
> + int64_t offset, PreallocMode prealloc,
> + bool ws_zero_supported, Error **errp)
> +{
> + uint64_t current_length;
> + char *buf = NULL;
> + int ret;
> +
> + ret = rbd_get_size(image, ¤t_length);
> + if (ret < 0) {
> + error_setg_errno(errp, -ret, "Failed to get file length");
> + goto out;
> + }
> +
> + if (current_length > offset && prealloc != PREALLOC_MODE_OFF) {
> + error_setg(errp, "Cannot use preallocation for shrinking files");
> + ret = -ENOTSUP;
> + goto out;
> + }
> +
> + switch (prealloc) {
> + case PREALLOC_MODE_FULL: {
> + uint64_t buf_size, current_offset = current_length;
> + ssize_t bytes;
> +
> + ret = rbd_get_stripe_unit(image, &buf_size);
> + if (ret < 0) {
> + error_setg_errno(errp, -ret, "Failed to get stripe unit");
> + goto out;
> + }
> +
> + ret = rbd_resize(image, offset);
> + if (ret < 0) {
> + error_setg_errno(errp, -ret, "Failed to resize file");
> + goto out;
> + }
> +
> + buf = g_malloc0(buf_size);
> +
> +#ifdef LIBRBD_SUPPORTS_WRITESAME
> + if (ws_zero_supported) {
> + uint64_t writesame_max_size;
> + int max_concurrent_ops;
> +
> + max_concurrent_ops = qemu_rbd_get_max_concurrent_ops(cluster);
> + /*
> + * We limit the rbd_writesame() size to avoid to spawn more then
> + * 'rbd_concurrent_management_ops' concurrent operations.
> + */
> + writesame_max_size = MIN(buf_size * max_concurrent_ops, INT_MAX);
> +
> + while (offset - current_offset > buf_size) {
> + bytes = MIN(offset - current_offset, writesame_max_size);
> + /*
> + * rbd_writesame() supports only request where the size of
> the
> + * operation is multiple of buffer size.
> + */
> + bytes -= bytes % buf_size;
> +
> + bytes = rbd_writesame(image, current_offset, bytes, buf,
> + buf_size, 0);
> + if (bytes < 0) {
> + ret = bytes;
> + error_setg_errno(errp, -ret,
> + "Failed to write for preallocation");
> + goto out;
> + }
> +
> + current_offset += bytes;
> + }
> + }
> +#endif /* LIBRBD_SUPPORTS_WRITESAME */
> +
> + while (current_offset < offset) {
> + bytes = rbd_write(image, current_offset,
> + MIN(offset - current_offset, buf_size), buf);
> + if (bytes < 0) {
> + ret = bytes;
> + error_setg_errno(errp, -ret,
> + "Failed to write for preallocation");
> + goto out;
> + }
> +
> + current_offset += bytes;
> + }
> +
> + ret = rbd_flush(image);
> + if (ret < 0) {
> + error_setg_errno(errp, -ret, "Failed to flush the file");
> + goto out;
> + }
> +
> + break;
> + }
> + case PREALLOC_MODE_OFF:
> + ret = rbd_resize(image, offset);
> + if (ret < 0) {
> + error_setg_errno(errp, -ret, "Failed to resize file");
> + goto out;
> + }
> + break;
> + default:
> + error_setg(errp, "Unsupported preallocation mode: %s",
> + PreallocMode_str(prealloc));
> + ret = -ENOTSUP;
> + goto out;
> + }
> +
> + ret = 0;
> +
> +out:
> + g_free(buf);
> + return ret;
> +}
> +
> +static bool qemu_rbd_writesame_zero_supported(rados_t *cluster)
> +{
> + int ret = 1;
> +
> +#ifdef LIBRBD_SUPPORTS_WRITESAME
> + /*
> + * When "rbd_discard_on_zeroed_write_same" is not available,
> rbd_writesame()
> + * can discard requests with zeroed buffer.
> + */
> + ret = rados_conf_set(*cluster, "rbd_discard_on_zeroed_write_same",
> "false");
> +#endif
> +
> + return ret == 0;
> +}
> +
> static QemuOptsList runtime_opts = {
> .name = "rbd",
> .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
> @@ -378,6 +529,7 @@ static int qemu_rbd_do_create(BlockdevCreateOptions
> *options,
> BlockdevCreateOptionsRbd *opts = &options->u.rbd;
> rados_t cluster;
> rados_ioctx_t io_ctx;
> + rbd_image_t image;
> int obj_order = 0;
> int ret;
>
> @@ -406,13 +558,23 @@ static int qemu_rbd_do_create(BlockdevCreateOptions
> *options,
> return ret;
> }
>
> - ret = rbd_create(io_ctx, opts->location->image, opts->size, &obj_order);
> + ret = rbd_create(io_ctx, opts->location->image, 0, &obj_order);
> if (ret < 0) {
> error_setg_errno(errp, -ret, "error rbd create");
> goto out;
> }
>
> - ret = 0;
> + ret = rbd_open(io_ctx, opts->location->image, &image, NULL);
> + if (ret < 0) {
> + error_setg_errno(errp, -ret, "error rbd open");
> + goto out;
> + }
> +
> + ret = qemu_rbd_do_truncate(cluster, image, opts->size,
> opts->preallocation,
> + qemu_rbd_writesame_zero_supported(&cluster),
> + errp);
> +
> + rbd_close(image);
> out:
> rados_ioctx_destroy(io_ctx);
> rados_shutdown(cluster);
> @@ -433,6 +595,7 @@ static int coroutine_fn qemu_rbd_co_create_opts(const
> char *filename,
> BlockdevOptionsRbd *loc;
> Error *local_err = NULL;
> const char *keypairs, *password_secret;
> + char *prealloc;
> QDict *options = NULL;
> int ret = 0;
>
> @@ -451,6 +614,16 @@ static int coroutine_fn qemu_rbd_co_create_opts(const
> char *filename,
> BLOCK_OPT_CLUSTER_SIZE,
> 0);
> rbd_opts->has_cluster_size = (rbd_opts->cluster_size != 0);
>
> + prealloc = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
> + rbd_opts->preallocation = qapi_enum_parse(&PreallocMode_lookup, prealloc,
> + PREALLOC_MODE_OFF, &local_err);
> + g_free(prealloc);
> + if (local_err) {
> + ret = -EINVAL;
> + error_propagate(errp, local_err);
> + goto exit;
> + }
> +
> options = qdict_new();
> qemu_rbd_parse_filename(filename, options, &local_err);
> if (local_err) {
> @@ -770,6 +943,7 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict
> *options, int flags,
>
> s->snap = g_strdup(opts->snapshot);
> s->image_name = g_strdup(opts->image);
> + s->ws_zero_supported = qemu_rbd_writesame_zero_supported(&s->cluster);
>
> /* rbd_open is always r/w */
> r = rbd_open(s->io_ctx, s->image_name, &s->image, s->snap);
> @@ -1089,21 +1263,16 @@ static int coroutine_fn
> qemu_rbd_co_truncate(BlockDriverState *bs,
> PreallocMode prealloc,
> Error **errp)
> {
> - int r;
> -
> - if (prealloc != PREALLOC_MODE_OFF) {
> - error_setg(errp, "Unsupported preallocation mode '%s'",
> - PreallocMode_str(prealloc));
> - return -ENOTSUP;
> - }
> + BDRVRBDState *s = bs->opaque;
> + int ret;
>
> - r = qemu_rbd_resize(bs, offset);
> - if (r < 0) {
> - error_setg_errno(errp, -r, "Failed to resize file");
> - return r;
> + ret = qemu_rbd_do_truncate(s->cluster, s->image, offset, prealloc,
> + s->ws_zero_supported, errp);
> + if (ret == 0) {
> + s->image_size = offset;
> }
>
> - return 0;
> + return ret;
> }
>
> static int qemu_rbd_snap_create(BlockDriverState *bs,
> @@ -1256,6 +1425,11 @@ static QemuOptsList qemu_rbd_create_opts = {
> .type = QEMU_OPT_SIZE,
> .help = "RBD object size"
> },
> + {
> + .name = BLOCK_OPT_PREALLOC,
> + .type = QEMU_OPT_STRING,
> + .help = "Preallocation mode (allowed values: off, full)"
> + },
> {
> .name = "password-secret",
> .type = QEMU_OPT_STRING,
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 0d43d4f37c..ff55171f8d 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -4346,13 +4346,16 @@
> # point to a snapshot.
> # @size Size of the virtual disk in bytes
> # @cluster-size RBD object size
> +# @preallocation Preallocation mode for the new image (since: 4.2)
> +# (default: off; allowed values: off, full)
> #
> # Since: 2.12
> ##
> { 'struct': 'BlockdevCreateOptionsRbd',
> 'data': { 'location': 'BlockdevOptionsRbd',
> 'size': 'size',
> - '*cluster-size' : 'size' } }
> + '*cluster-size' : 'size',
> + '*preallocation': 'PreallocMode' } }
>
> ##
> # @BlockdevVmdkSubformat:
I think I don't see anything obviously wrong, but note that I don't know ceph
yet,
thus I might have missed something.
So:
Reviewed-by: Maxim Levitsky <mlevi...@redhat.com>
Best regards,
Maxim Levitsky
