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| From: | Vladimir Sementsov-Ogievskiy |
| Subject: | Re: [Qemu-devel] [Qemu-block] [PATCH v3 1/3] block: add bdrv_get_format_alloc_stat format interface |
| Date: | Wed, 28 Jun 2017 18:59:32 +0300 |
| User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 |
27.06.2017 02:19, John Snow wrote:
On 06/06/2017 12:26 PM, Vladimir Sementsov-Ogievskiy wrote: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 <address@hidden> --- block.c | 16 ++++++++++++++ include/block/block.h | 3 +++ include/block/block_int.h | 2 ++ qapi/block-core.json | 55 +++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 76 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. + */ +int bdrv_get_format_alloc_stat(BlockDriverState *bs, BlockFormatAllocInfo *bfai) +{ + 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..fd7b52bd69 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -139,6 +139,61 @@ '*format-specific': 'ImageInfoSpecific' } }##+# @BlockFormatAllocInfo: +#I apologize in advance, but I don't understand this patch very well. Let me ask some questions to get patch review rolling again, since you've been waiting a bit.+# +# Allocation relations between format file and underlying protocol file. +# All fields are in bytes. +#The format file in this case would be ... what, the virtual file represented by the qcow2? and the underlying protocol file is the raw file that is the qcow2 itself?
yes
+# There are two types of the format file portions: 'used' and 'unused'. It's up +# to the format how to interpret these types. For now the only format supporting +# the feature is Qcow2 and for this case 'used' are clusters with positive +# refcount and unused a clusters with zero refcount. Described portions include +# all format file allocations, not only virtual disk data (metadata, internal +# snapshots, etc. are included).I guess the semantic differentiation between "used" and "unused" is left to the individual fields, below.
hmm, I don't understand. differentiation is up to the format, and for qcow2 it is described above
+# +# For the underlying file there are native block-status types of the portions: +# - data: allocated data +# - zero: read-as-zero holes +# - discarded: not allocated +# 4th additional type is 'overrun', which is for the format file portions beyond +# the end of the underlying file. +# +# So, the fields are: +# +# @used-data: used by the format file and backed by data in the underlying file +#I assume this is "defined and addressable data".+# @used-zero: used by the format file and backed by a hole in the underlying +# file +#By a hole? Can you give me an example? Do you mean like a filesystem hole ala falloc()?
-zero, -data and -discarded are the block status of corresponding area in underlying file.
so, if underlying file is raw, yes, it should be a filesystem hole. example: ------------------------- # ./qemu-img create -f qcow2 x 1GFormatting 'x', fmt=qcow2 size=1073741824 encryption=off cluster_size=65536 lazy_refcounts=off refcount_bits=16
# ./qemu-img check x
No errors were found on the image.
Image end offset: 262144
Format allocation info (including metadata):
data zero discarded after-eof
used 192 KiB 0 B 0 B 63.5 KiB
unused 0 B 0 B 0 B
# ./qemu-io -c 'write 0 100M' x
wrote 104857600/104857600 bytes at offset 0
100 MiB, 1 ops; 0.7448 sec (134.263 MiB/sec and 1.3426 ops/sec)
# ./qemu-img check x
No errors were found on the image.
1600/16384 = 9.77% allocated, 0.00% fragmented, 0.00% compressed clusters
Image end offset: 105185280
Format allocation info (including metadata):
data zero discarded after-eof
used 100 MiB 60 KiB 0 B 0 B
unused 0 B 0 B 0 B
# ./qemu-io -c 'discard 0 1M' x
discard 1048576/1048576 bytes at offset 0
1 MiB, 1 ops; 0.0002 sec (3.970 GiB/sec and 4065.0407 ops/sec)
# ./qemu-img check x
No errors were found on the image.
1584/16384 = 9.67% allocated, 0.00% fragmented, 0.00% compressed clusters
Image end offset: 105185280
Format allocation info (including metadata):
data zero discarded after-eof
used 99.3 MiB 60 KiB 0 B 0 B
unused 0 B 1 MiB 0 B
-------------------------
- hmm, 60 KiB, don't know what is it. some preallocation may be..
+# @used-discarded: used by the format file but actually unallocated in the +# underlying file +#In what case do we have used data that is discarded/undefined, but not zero? Shouldn't discarded data be zero...?
may be discarded is bad name.. this if for unallocated block status of underlying file.
+# @used-overrun: used by the format file beyond the end of the underlying file +#When does this occur?
I think it shoud be some kind of corruption.
+# @unused-data: allocated data in the underlying file not used by the format +#I assume this is an allocation gap in qcow2. Unused, but non-zero. Right?
or it may be some kind of error or due to underlying fs doesn't maintain holes.
+# @unused-zero: holes in the underlying file not used by the format file +#I assume this is similar to the above -- Unused, but zero.
Unused and underlying block status is ZERO. It is a "good" case for unused areas.
+# @unused-discarded: unallocated areas in the underlying file not used by the +# format file +#Again I am unsure of what discarded but non-zero might mean.
looks like for raw format discarded is impossible, but to make a generic tool, let's consider block status = unallocated too.
+# Note: sum of 6 fields {used,unused}-{data,zero,discarded} is equal to the +# length of the underlying file. +# +# Since: 2.10 +# +## +{ 'struct': 'BlockFormatAllocInfo', + 'data': {'used-data': 'uint64', + 'used-zero': 'uint64', + 'used-discarded': 'uint64', + 'used-overrun': 'uint64', + 'unused-data': 'uint64', + 'unused-zero': 'uint64', + 'unused-discarded': 'uint64' } } + +## # @ImageCheck: # # Information about a QEMU image file checkSorry for the dumb questions.
Don't worry)
--John
-- Best regards, Vladimir
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