Cc: Eric Blake for additional schema review expertise.
Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> writes:
> The function should collect statistics, about used/unused by top-level
> format driver space (in its .file) and allocation status
> (data/zero/discarded/after-eof) of corresponding areas in this .file.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
> ---
> block.c | 16 +++++++++++
> include/block/block.h | 3 ++
> include/block/block_int.h | 2 ++
> qapi/block-core.json | 72
> +++++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 93 insertions(+)
>
> diff --git a/block.c b/block.c
> index 50ba264143..7d720ae0c2 100644
> --- a/block.c
> +++ b/block.c
> @@ -3407,6 +3407,22 @@ int64_t bdrv_get_allocated_file_size(BlockDriverState
> *bs)
> }
>
> /**
> + * Collect format allocation info. See BlockFormatAllocInfo definition in
> + * qapi/block-core.json.
> + */
I'd prefer
/**
* Collect format allocation info.
* See BlockFormatAllocInfo definition in qapi/block-core.json.
*/
Admittedly a matter of taste.
> +int bdrv_get_format_alloc_stat(BlockDriverState *bs, BlockFormatAllocInfo
> *bfai)
bdrv_get_format_alloc_info(), please, for symmetry with
BlockFormatAllocInfo.
> +{
> + BlockDriver *drv = bs->drv;
> + if (!drv) {
> + return -ENOMEDIUM;
> + }
> + if (drv->bdrv_get_format_alloc_stat) {
> + return drv->bdrv_get_format_alloc_stat(bs, bfai);
> + }
> + return -ENOTSUP;
> +}
> +
> +/**
> * Return number of sectors on success, -errno on error.
> */
> int64_t bdrv_nb_sectors(BlockDriverState *bs)
> diff --git a/include/block/block.h b/include/block/block.h
> index 9b355e92d8..646376a772 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -335,6 +335,9 @@ typedef enum {
>
> int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode
> fix);
>
> +int bdrv_get_format_alloc_stat(BlockDriverState *bs,
> + BlockFormatAllocInfo *bfai);
> +
> /* The units of offset and total_work_size may be chosen arbitrarily by the
> * block driver; total_work_size may change during the course of the
> amendment
> * operation */
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 8d3724cce6..458c715e99 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -208,6 +208,8 @@ struct BlockDriver {
> int64_t (*bdrv_getlength)(BlockDriverState *bs);
> bool has_variable_length;
> int64_t (*bdrv_get_allocated_file_size)(BlockDriverState *bs);
> + int (*bdrv_get_format_alloc_stat)(BlockDriverState *bs,
> + BlockFormatAllocInfo *bfai);
>
> int coroutine_fn (*bdrv_co_pwritev_compressed)(BlockDriverState *bs,
> uint64_t offset, uint64_t bytes, QEMUIOVector *qiov);
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index ea0b3e8b13..93f6995381 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -139,6 +139,78 @@
> '*format-specific': 'ImageInfoSpecific' } }
>
> ##
> +# @BlockFormatAllocInfo:
> +#
> +#
Just one blank like, please.
> +# Allocation information of an underlying protocol file, as partitioned by a
> +# format driver's utilization of said allocations.
> +# All fields are in bytes.
> +#
> +# Regions of the underlying protocol file may be considered used or unused by
> +# the format driver interpreting these regions. It is at the discretion of
> the
> +# format driver (e.g. qcow2) which regions of its backing storage are
> considered
Long line. Please wrap your comment lines around column 70 for legibility.
> +# in-use or not.
> +#
> +# For now, the only format driver supporting this feature is Qcow2 which is a
"is QCow2, which"
> +# cluster based format. Clusters considered in-use by qcow2 are those with a
> +# non-zero refcount in the format metadata. All other clusters, if present,
> are
> +# considered unused. Examples of unused allocations for the Qcow2 format are
> +# leaked clusters, pre-allocated clusters, and recently freed clusters.
> +#
> +# Note: the whole underlying protocol file is described as well as all format
> +# file allocations, not only virtual disk data (metadata, internal snapshots,
> +# etc. are included).
I'm not sure I get this note.
> +#
> +# For the underlying protocol file there are native block-status types of the
> +# regions:
Comma after "protocol file"? The sentence doesn't feel right to me even
with the comma, though. What's a "native block-status type"?
> +# - data: allocated data
> +# - zero: reported as zero (for example, this type corresponds to holes for
> +# POSIX files on sparce file-system)
> +# - discarded: not allocated
> +# 4th additional type is 'overrun', is data referenced by the format driver
> +# located beyond EOF of the underlying protocol file. For example, a
> partially
> +# allocated cluster at the end of a QCOW2 file, where Qcow2 generally
> operates
> +# on complete clusters.
Explaining three of four types in a list, and the fourth in the
paragraph following the list feels awkward. Turn it into a fourth list
item?
> +#
> +# So, the fields are:
> +#
> +# @used-data: used by the format file and backed by data in the underlying
> +# protocol file
> +#
> +# @used-zero: used by the format file and backed by zeroes in the underlying
> +# protocol file; which may be a filesystem hole for POSIX files.
> +#
> +# @used-discarded: used by the format file but actually unallocated in the
> +# underlying protocol file
Are discarded clusters normal or some kind of problem?
> +#
> +# @used-overrun: used by the format file beyond the end of the underlying
> +# protocol file
Are overruns normal or some kind of problem?
> +#
> +# @unused-data: allocated data in the underlying protocol file not used by
> the
> +# format file
> +#
> +# @unused-zero: reported-as-zero regions in the underlying protocol file not
> +# used by the format file
> +#
> +# @unused-discarded: unallocated areas in the underlying protocol file not
> used
> +# by the format file
> +#
> +# Note: sum of 6 fields {used,unused}-{data,zero,discarded} is equal to the
> +# length of the underlying protocol file.
> +#
> +# Since: 2.11
> +#
> +##
> +{ 'struct': 'BlockFormatAllocInfo',
> + 'data': {'used-data': 'uint64',
> + 'used-zero': 'uint64',
> + 'used-discarded': 'uint64',
> + 'used-overrun': 'uint64',
> + 'unused-data': 'uint64',
> + 'unused-zero': 'uint64',
> + 'unused-discarded': 'uint64' } }
Please use 'size' for byte counts. See also "[RFC PATCH 00/56] qapi:
Use 'size' for byte counts & offsets".
> +
> +##
> # @ImageCheck:
> #
> # Information about a QEMU image file check
