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Re: [Qemu-devel] [PATCH 8/9] block: Introduce BlockDriver.bdrv_drain cal
From: |
Fam Zheng |
Subject: |
Re: [Qemu-devel] [PATCH 8/9] block: Introduce BlockDriver.bdrv_drain callback |
Date: |
Thu, 29 Oct 2015 09:38:39 +0800 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Wed, 10/28 11:13, Kevin Wolf wrote:
> Am 26.10.2015 um 07:24 hat Fam Zheng geschrieben:
> > Drivers can have internal request sources that generate IO, like the
> > need_check_timer in QED. Since we want quiesced periods that contain
> > nested event loops in block layer, we need to have a way to disable such
> > event sources.
> >
> > Block drivers must implement the "bdrv_drain" callback if it has any
> > internal sources that can generate I/O activity, like a timer or a
> > worker thread (even in a library) that can schedule QEMUBH in an
> > asynchronous callback.
> >
> > Update the comments of bdrv_drain and bdrv_drained_begin accordingly.
> >
> > Signed-off-by: Fam Zheng <address@hidden>
> > Reviewed-by: Jeff Cody <address@hidden>
> > Reviewed-by: Kevin Wolf <address@hidden>
> > ---
> > block/io.c | 6 +++++-
> > include/block/block_int.h | 6 ++++++
> > 2 files changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/block/io.c b/block/io.c
> > index 358c3c4..a740827 100644
> > --- a/block/io.c
> > +++ b/block/io.c
> > @@ -234,7 +234,8 @@ bool bdrv_requests_pending(BlockDriverState *bs)
> > }
> >
> > /*
> > - * Wait for pending requests to complete on a single BlockDriverState
> > subtree
> > + * Wait for pending requests to complete on a single BlockDriverState
> > subtree,
> > + * and suspend block driver's internal I/O until next request arrives.
> > *
> > * Note that unlike bdrv_drain_all(), the caller must hold the
> > BlockDriverState
> > * AioContext.
> > @@ -247,6 +248,9 @@ void bdrv_drain(BlockDriverState *bs)
> > {
> > bool busy = true;
> >
> > + if (bs->drv && bs->drv->bdrv_drain) {
> > + bs->drv->bdrv_drain(bs);
> > + }
>
> Does this need to be recursive? Recursing into bs->file and bs->backing
> would be consistent with the current bdrv_requests_pending(); but I'm
> planning to send a patch to extend this to all children.
>
Yes, I'll change it to recurse into all children.
Fam
- Re: [Qemu-devel] [PATCH 3/9] block: Track discard requests, (continued)
- [Qemu-devel] [PATCH 4/9] iscsi: Emulate commands in iscsi_aio_ioctl as iscsi_ioctl, Fam Zheng, 2015/10/26
- [Qemu-devel] [PATCH 5/9] block: Add ioctl parameter fields to BlockRequest, Fam Zheng, 2015/10/26
- [Qemu-devel] [PATCH 6/9] block: Emulate bdrv_ioctl with bdrv_aio_ioctl and track both, Fam Zheng, 2015/10/26
- [Qemu-devel] [PATCH 7/9] block: Drop BlockDriver.bdrv_ioctl, Fam Zheng, 2015/10/26
- [Qemu-devel] [PATCH 8/9] block: Introduce BlockDriver.bdrv_drain callback, Fam Zheng, 2015/10/26
- [Qemu-devel] [PATCH 9/9] qed: Implement .bdrv_drain, Fam Zheng, 2015/10/26
- Re: [Qemu-devel] [PATCH 0/9] block: Fixes for bdrv_drain, Kevin Wolf, 2015/10/28