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Re: [Qemu-devel] [PATCH v3 09/22] blkdebug: Set request_alignment during
From: |
Fam Zheng |
Subject: |
Re: [Qemu-devel] [PATCH v3 09/22] blkdebug: Set request_alignment during .bdrv_refresh_limits() |
Date: |
Fri, 24 Jun 2016 13:42:14 +0800 |
User-agent: |
Mutt/1.6.1 (2016-04-27) |
On Thu, 06/23 16:37, Eric Blake wrote:
> We want to eventually stick request_alignment alongside other
> BlockLimits, but first, we must ensure it is populated at the
> same time as all other limits, rather than being a special case
> that is set only when a block is first opened.
>
> Note that when the user does not provide "align", then we were
> defaulting to bs->request_alignment - but at this stage in the
> initialization, that was always 512. We were also rejecting an
> explicit "align":0 from the user; this patch now allows that,
> as an explicit request for the default alignment (which may not
> always be 512 in the future).
>
> qemu-iotests 77 is particularly sensitive to the fact that we
> can specify an artificial alignment override in blkdebug, and
> that override must continue to work even when limits are
> refreshed on an already open device.
>
> Signed-off-by: Eric Blake <address@hidden>
>
> ---
> v3: rework to allow user to specify "align":0 for default
> v2: new patch
> ---
> qapi/block-core.json | 3 ++-
> block/blkdebug.c | 19 +++++++++++++++----
> 2 files changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 98a20d2..ac8f5f6 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -1961,7 +1961,8 @@
> #
> # @config: #optional filename of the configuration file
> #
> -# @align: #optional required alignment for requests in bytes
> +# @align: #optional required alignment for requests in bytes,
> +# must be power of 2, or 0 for default
> #
> # @inject-error: #optional array of error injection descriptions
> #
> diff --git a/block/blkdebug.c b/block/blkdebug.c
> index 20d25bd..54b6870 100644
> --- a/block/blkdebug.c
> +++ b/block/blkdebug.c
> @@ -37,6 +37,7 @@
> typedef struct BDRVBlkdebugState {
> int state;
> int new_state;
> + int align;
>
> QLIST_HEAD(, BlkdebugRule) rules[BLKDBG__MAX];
> QSIMPLEQ_HEAD(, BlkdebugRule) active_rules;
> @@ -382,10 +383,10 @@ static int blkdebug_open(BlockDriverState *bs, QDict
> *options, int flags,
> }
>
> /* Set request alignment */
> - align = qemu_opt_get_size(opts, "align", bs->request_alignment);
> - if (align > 0 && align < INT_MAX && !(align & (align - 1))) {
> - bs->request_alignment = align;
> - } else {
> + align = qemu_opt_get_size(opts, "align", 0);
> + if (align < INT_MAX && is_power_of_2(align)) {
> + s->align = align;
> + } else if (align) {
> error_setg(errp, "Invalid alignment");
> ret = -EINVAL;
> goto fail_unref;
> @@ -720,6 +721,15 @@ static void blkdebug_refresh_filename(BlockDriverState
> *bs, QDict *options)
> bs->full_open_options = opts;
> }
>
> +static void blkdebug_refresh_limits(BlockDriverState *bs, Error **errp)
> +{
> + BDRVBlkdebugState *s = bs->opaque;
> +
> + if (s->align) {
> + bs->request_alignment = s->align;
> + }
> +}
> +
> static int blkdebug_reopen_prepare(BDRVReopenState *reopen_state,
> BlockReopenQueue *queue, Error **errp)
> {
> @@ -738,6 +748,7 @@ static BlockDriver bdrv_blkdebug = {
> .bdrv_getlength = blkdebug_getlength,
> .bdrv_truncate = blkdebug_truncate,
> .bdrv_refresh_filename = blkdebug_refresh_filename,
> + .bdrv_refresh_limits = blkdebug_refresh_limits,
>
> .bdrv_aio_readv = blkdebug_aio_readv,
> .bdrv_aio_writev = blkdebug_aio_writev,
> --
> 2.5.5
>
Reviewed-by: Fam Zheng <address@hidden>
- [Qemu-devel] [PATCH v3 00/22] Byte-based block limits, Eric Blake, 2016/06/23
- [Qemu-devel] [PATCH v3 04/22] nbd: Allow larger requests, Eric Blake, 2016/06/23
- [Qemu-devel] [PATCH v3 09/22] blkdebug: Set request_alignment during .bdrv_refresh_limits(), Eric Blake, 2016/06/23
- Re: [Qemu-devel] [PATCH v3 09/22] blkdebug: Set request_alignment during .bdrv_refresh_limits(),
Fam Zheng <=
- [Qemu-devel] [PATCH v3 08/22] block: Give nonzero result to blk_get_max_transfer_length(), Eric Blake, 2016/06/23
- [Qemu-devel] [PATCH v3 02/22] block: Document supported flags during bdrv_aligned_preadv(), Eric Blake, 2016/06/23
- [Qemu-devel] [PATCH v3 06/22] iscsi: Advertise realistic limits to block layer, Eric Blake, 2016/06/23
- [Qemu-devel] [PATCH v3 05/22] nbd: Advertise realistic limits to block layer, Eric Blake, 2016/06/23
- [Qemu-devel] [PATCH v3 07/22] scsi: Advertise limits by blocksize, not 512, Eric Blake, 2016/06/23
- [Qemu-devel] [PATCH v3 01/22] block: Tighter assertions on bdrv_aligned_pwritev(), Eric Blake, 2016/06/23
- [Qemu-devel] [PATCH v3 13/22] block: Set request_alignment during .bdrv_refresh_limits(), Eric Blake, 2016/06/23
- [Qemu-devel] [PATCH v3 10/22] iscsi: Set request_alignment during .bdrv_refresh_limits(), Eric Blake, 2016/06/23