* [Qemu-devel] [PATCH v3] block: document semanatics of bdrv_co_preadv|pwritev
@ 2017-08-04 14:08 Daniel P. Berrange
2017-08-04 14:28 ` Eric Blake
2017-08-08 10:16 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
0 siblings, 2 replies; 4+ messages in thread
From: Daniel P. Berrange @ 2017-08-04 14:08 UTC (permalink / raw)
To: qemu-devel
Cc: Kevin Wolf, Max Reitz, qemu-block, Eric Blake, Daniel P. Berrange
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
- Clarify that @bytes matches @qiov total size (Kevin)
include/block/block_int.h | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/include/block/block_int.h b/include/block/block_int.h
index d4f4ea7584..4f7f20e56b 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -147,12 +147,43 @@ struct BlockDriver {
int coroutine_fn (*bdrv_co_readv)(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
+
+ /**
+ * @offset: position in bytes to read at
+ * @bytes: number of bytes to read
+ * @qiov: the buffers to fill with read data
+ * @flags: currently unused, always 0
+ *
+ * @offset and @bytes will be a multiple of 'request_alignment',
+ * but the length of individual @qiov elements does not have to
+ * be a multiple.
+ *
+ * @bytes will always equal the total size of @qiov, and will be
+ * no larger than 'max_transfer'.
+ *
+ * The buffer in @qiov may point directly to guest memory.
+ */
int coroutine_fn (*bdrv_co_preadv)(BlockDriverState *bs,
uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags);
int coroutine_fn (*bdrv_co_writev)(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
int coroutine_fn (*bdrv_co_writev_flags)(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, int flags);
+ /**
+ * @offset: position in bytes to write at
+ * @bytes: number of bytes to write
+ * @qiov: the buffers containing data to write
+ * @flags: zero or more of bits allowed by 'supported_write_flags'
+ *
+ * @offset and @bytes will be a multiple of 'request_alignment',
+ * but the length of individual @qiov elements does not have to
+ * be a multiple.
+ *
+ * @bytes will always equal the total size of @qiov, and will be
+ * no larger than 'max_transfer'.
+ *
+ * The buffer in @qiov may point directly to guest memory.
+ */
int coroutine_fn (*bdrv_co_pwritev)(BlockDriverState *bs,
uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags);
--
2.13.3
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH v3] block: document semanatics of bdrv_co_preadv|pwritev
2017-08-04 14:08 [Qemu-devel] [PATCH v3] block: document semanatics of bdrv_co_preadv|pwritev Daniel P. Berrange
@ 2017-08-04 14:28 ` Eric Blake
2017-08-04 15:15 ` Daniel P. Berrange
2017-08-08 10:16 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
1 sibling, 1 reply; 4+ messages in thread
From: Eric Blake @ 2017-08-04 14:28 UTC (permalink / raw)
To: Daniel P. Berrange, qemu-devel; +Cc: Kevin Wolf, Max Reitz, qemu-block
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On 08/04/2017 09:08 AM, Daniel P. Berrange wrote:
> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> ---
>
> - Clarify that @bytes matches @qiov total size (Kevin)
>
> include/block/block_int.h | 31 +++++++++++++++++++++++++++++++
> 1 file changed, 31 insertions(+)
[looks like the nongnu.org infrastructure is having heavy load today, so
mails are getting through more slowly than usual - leads to lots of
crossed emails, where I'm seeing replies or direct sends sooner than
list copies]
> + /**
> + * @offset: position in bytes to write at
> + * @bytes: number of bytes to write
> + * @qiov: the buffers containing data to write
> + * @flags: zero or more of bits allowed by 'supported_write_flags'
maybe s/of //
> + *
> + * @offset and @bytes will be a multiple of 'request_alignment',
> + * but the length of individual @qiov elements does not have to
> + * be a multiple.
> + *
> + * @bytes will always equal the total size of @qiov, and will be
> + * no larger than 'max_transfer'.
> + *
> + * The buffer in @qiov may point directly to guest memory.
> + */
> int coroutine_fn (*bdrv_co_pwritev)(BlockDriverState *bs,
> uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags);
Do we make guarantees that the driver callback is never reached if the
image is currently read-only? If so, is that a guarantee worth documenting?
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH v3] block: document semanatics of bdrv_co_preadv|pwritev
2017-08-04 14:28 ` Eric Blake
@ 2017-08-04 15:15 ` Daniel P. Berrange
0 siblings, 0 replies; 4+ messages in thread
From: Daniel P. Berrange @ 2017-08-04 15:15 UTC (permalink / raw)
To: Eric Blake; +Cc: qemu-devel, Kevin Wolf, Max Reitz, qemu-block
On Fri, Aug 04, 2017 at 09:28:54AM -0500, Eric Blake wrote:
> On 08/04/2017 09:08 AM, Daniel P. Berrange wrote:
> > Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> > ---
> >
> > - Clarify that @bytes matches @qiov total size (Kevin)
> >
> > include/block/block_int.h | 31 +++++++++++++++++++++++++++++++
> > 1 file changed, 31 insertions(+)
>
> [looks like the nongnu.org infrastructure is having heavy load today, so
> mails are getting through more slowly than usual - leads to lots of
> crossed emails, where I'm seeing replies or direct sends sooner than
> list copies]
>
> > + /**
> > + * @offset: position in bytes to write at
> > + * @bytes: number of bytes to write
> > + * @qiov: the buffers containing data to write
> > + * @flags: zero or more of bits allowed by 'supported_write_flags'
>
> maybe s/of //
>
> > + *
> > + * @offset and @bytes will be a multiple of 'request_alignment',
> > + * but the length of individual @qiov elements does not have to
> > + * be a multiple.
> > + *
> > + * @bytes will always equal the total size of @qiov, and will be
> > + * no larger than 'max_transfer'.
> > + *
> > + * The buffer in @qiov may point directly to guest memory.
> > + */
> > int coroutine_fn (*bdrv_co_pwritev)(BlockDriverState *bs,
> > uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags);
>
> Do we make guarantees that the driver callback is never reached if the
> image is currently read-only? If so, is that a guarantee worth documenting?
bdrv_co_pwritev() returns EPERM if bs->read_only, so it looks like you
are right we have a guarantee we can document
> Reviewed-by: Eric Blake <eblake@redhat.com>
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [Qemu-block] [PATCH v3] block: document semanatics of bdrv_co_preadv|pwritev
2017-08-04 14:08 [Qemu-devel] [PATCH v3] block: document semanatics of bdrv_co_preadv|pwritev Daniel P. Berrange
2017-08-04 14:28 ` Eric Blake
@ 2017-08-08 10:16 ` Stefan Hajnoczi
1 sibling, 0 replies; 4+ messages in thread
From: Stefan Hajnoczi @ 2017-08-08 10:16 UTC (permalink / raw)
To: Daniel P. Berrange; +Cc: qemu-devel, Kevin Wolf, qemu-block, Max Reitz
[-- Attachment #1: Type: text/plain, Size: 360 bytes --]
On Fri, Aug 04, 2017 at 03:08:26PM +0100, Daniel P. Berrange wrote:
> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> ---
>
> - Clarify that @bytes matches @qiov total size (Kevin)
>
> include/block/block_int.h | 31 +++++++++++++++++++++++++++++++
> 1 file changed, 31 insertions(+)
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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^ permalink raw reply [flat|nested] 4+ messages in thread
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2017-08-04 14:08 [Qemu-devel] [PATCH v3] block: document semanatics of bdrv_co_preadv|pwritev Daniel P. Berrange
2017-08-04 14:28 ` Eric Blake
2017-08-04 15:15 ` Daniel P. Berrange
2017-08-08 10:16 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
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