| Message ID | 20170606162652.112122-2-vsementsov@virtuozzo.com |
|---|---|
| State | New |
| Headers | show |
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 <vsementsov@virtuozzo.com> > --- > 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? > +# 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. > +# > +# 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()? > +# @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...? > +# @used-overrun: used by the format file beyond the end of the underlying file > +# When does this occur? > +# @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? > +# @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-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. > +# 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 check > Sorry for the dumb questions. --John
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 <vsementsov@virtuozzo.com> >> --- >> 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 1G Formatting '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 check >> > Sorry for the dumb questions. Don't worry) > > --John
On 06/28/2017 11:59 AM, Vladimir Sementsov-Ogievskiy wrote: > 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 <vsementsov@virtuozzo.com> >>> --- >>> 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 1G > Formatting '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 OK, we create a 196624 byte file -- 3 clusters and a little bit of extra. 0: header 1: reftable 2: refcount block #0, accounting for clusters 0x0 - 0x7fff 3: l1_table, only partially allocated, and all zeroes So we've got 16 bytes defined for this l1 table, leaving most of a cluster defined but after EOF. I suppose your after-EOF counter there is probably rounding a bit to the nearest 512. So we've got three used clusters, and 99% of one cluster that's after EOF. Shouldn't data here be 192.5 in this case? Or Data: 192KiB; Zero 512 b? I guess the ".5" is just truncated or rounded. > # ./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 Hmm, okay; now the image is 105185280 bytes; 102720 KiB; 1,605 clusters. 100MiB + 320KiB. Again, it doesn't entirely look like your summaries line up. Did we lose 256KiB to a rounding error under "100MiB" ? From what I can now tell, the map looks like: == File Map == 0x000000000 - 0x00004ffff [Metadata] (5 clusters) 0x000050000 - 0x00644ffff [Data] (1600 clusters) 1600 clusters at 64KiB each gives us 102400KiB / 100MiB of data. Then we've got five clusters of metadata (320KiB). Cluster 0: Header data. Data only occupies the first 512 bytes or so. Data: 512b Zeroes: 63.5KiB Cluster 1: Reftable. Data only occupies the first 8 bytes. Data: 512b Zeroes: 63.5KiB Cluster 2: Refcount Block #0. There are 0xC8A bytes, 3210/2 1605 refcounts. Makes sense. That's 7 sectors of data. Data: 3.5KiB Zeroes: 60.5KiB Cluster 3: L1 table. One entry for L2 table. Takes 8 bytes. Data: 512B Zeroes: 63.5KiB Cluster 4: L2 table. 1,600 entries. Takes 5120 bytes, about 10 sectors. Data: 5KiB Zeroes: 59KiB Then clusters 5-1604 contain our data contiguously, the ascii byte 0xcd. > # ./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.. > x doesn't lose any filesize, but we have 1584 allocated clusters. We lost 16, corresponding to the discarded 1M. Map is now: 0x000000000 - 0x00004ffff [Metadata] (5 clusters) 0x000050000 - 0x00014ffff [Vacant] (16 clusters) 0x000150000 - 0x00644ffff [Data] (1584 clusters) OK. 0: Header. no change. Data: 512b Zeroes: 63.5KiB 1: Reftable. No change. Data: 512b Zeroes: 63.5KiB Cluster 2: Almost the same.... ref[5] (i.e. the sixth) through ref[20] have been decremented, but everything else remains at refcount of 01. Still takes up the same amount of space at the sector granularity level. Data: 3.5KiB Zeroes: 60.5KiB Cluster 3: L1 table. No change. Data: 512B Zeroes: 63.5KiB Cluster 4: L2 table Here, the first 16 data clusters have been modified to zero cluster pointers: 0x0000000000000001, everything else remains defined as it was. Data: 5KiB Zeroes: 59KiB Clusters 5-20 inclusive: non-zero data now discarded and considered unused. 1MiB. makes sense. Clusters 21-end: non-zero, used data. 1584 clusters; 101376KiB; 99MiB My Tallies: Metadata: 10KiB Metadata Zeroes: 310KiB Undefined Data: 1MiB Data: 99MiB Your Tallies: 'used-data': 99.3MiB (101683.2KiB) 'used-zeroes': 60KiB 'unused-data': 1MiB Subtracting out the 99MiB of data surely accounted for correctly here; you are counting about 0.3MiB + 60KiB of used data for presumably the metadata regions; ~367.2KiB. Looks like your counts are something like: metadata: 260KiB (0.25MiB ... ~0.3 with rounding, OK) metadata-zeroes: 60KiB So it's probably just counting what is and isn't zeroes a little less aggressively than I am doing. To what extent or how, I don't know. Maybe it depends on the underlying filesystem: jhuston@probe ~> qemu-img map -f raw X Offset Length Mapped to File 0 0x31000 0 X 0x40000 0x10000 0x40000 X 0x150000 0x6300000 0x150000 X Looks like a hole from 0x31000 to 0x40000, 60KiB in the metadata region, so that's probably it. Then there's a hole from 0x50000 to 0x150000, 1MiB, so that's unused data. Hey, interesting, the discarded data that would be read as zeroes is still defined by the QCOW2 schema so that's "unused-zeroes" whereas the zero space in the metadata is only counted as such because of the sparse gap, so that's used-zero. OK, I think I'm starting to get what these numbers mean. > >> >>> +# @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. > Unallocated in what sense, exactly? Do you have an example for qcow2? I'm sorry that i still don't quite follow :\ >> >>> +# @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. > Alright, let me see if I have this straight... used-data: Normal data. We are standing on terra-firma. used-zero: Data that is defined to be zeroes in some way. (Does not necessarily include data clusters if they were not actually zeroed out, I think. May not include regions that ARE zero, even if they are literally zero, because the driver may not especially recognize them as such. Anything marked as zero will DEFINITELY be zero, though. Yes?) used-discarded: I'm not actually sure in this case. used-overrun: Data that is defined to exist, but appears to fall outside of or beyond EOF. Appears to happen with qcow2 metadata before any writes occur. unused-data: Normal data, but not in-use by the schema anywhere. Leaked clusters and the like, effectively. unused-zero: Similar to the above, but definitely zeroes. unused-discarded: Not really sure. >> >>> +# @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 check >>> >> Sorry for the dumb questions. > > Don't worry) > >> >> --John > >
29.06.2017 03:15, John Snow wrote: > > On 06/28/2017 11:59 AM, Vladimir Sementsov-Ogievskiy wrote: >> 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 <vsementsov@virtuozzo.com> >>>> --- >>>> 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 1G >> Formatting '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 > OK, we create a 196624 byte file -- 3 clusters and a little bit of extra. > > 0: header > 1: reftable > 2: refcount block #0, accounting for clusters 0x0 - 0x7fff > 3: l1_table, only partially allocated, and all zeroes > > So we've got 16 bytes defined for this l1 table, leaving most of a > cluster defined but after EOF. I suppose your after-EOF counter there is > probably rounding a bit to the nearest 512. > > So we've got three used clusters, and 99% of one cluster that's after > EOF. Shouldn't data here be 192.5 in this case? > > Or Data: 192KiB; Zero 512 b? > > I guess the ".5" is just truncated or rounded. > >> # ./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 > Hmm, okay; > > now the image is 105185280 bytes; 102720 KiB; 1,605 clusters. > 100MiB + 320KiB. Again, it doesn't entirely look like your summaries > line up. Did we lose 256KiB to a rounding error under "100MiB" ? > > From what I can now tell, the map looks like: > > == File Map == > > 0x000000000 - 0x00004ffff [Metadata] (5 clusters) > 0x000050000 - 0x00644ffff [Data] (1600 clusters) > > 1600 clusters at 64KiB each gives us 102400KiB / 100MiB of data. > Then we've got five clusters of metadata (320KiB). > > Cluster 0: Header data. Data only occupies the first 512 bytes or so. > Data: 512b > Zeroes: 63.5KiB > > Cluster 1: Reftable. Data only occupies the first 8 bytes. > Data: 512b > Zeroes: 63.5KiB > > Cluster 2: Refcount Block #0. There are 0xC8A bytes, 3210/2 1605 > refcounts. Makes sense. That's 7 sectors of data. > Data: 3.5KiB > Zeroes: 60.5KiB > > Cluster 3: L1 table. One entry for L2 table. Takes 8 bytes. > Data: 512B > Zeroes: 63.5KiB > > Cluster 4: L2 table. 1,600 entries. Takes 5120 bytes, about 10 sectors. > Data: 5KiB > Zeroes: 59KiB > > Then clusters 5-1604 contain our data contiguously, the ascii byte 0xcd. > >> # ./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.. >> > x doesn't lose any filesize, but we have 1584 allocated clusters. We > lost 16, corresponding to the discarded 1M. > > Map is now: > > 0x000000000 - 0x00004ffff [Metadata] (5 clusters) > 0x000050000 - 0x00014ffff [Vacant] (16 clusters) > 0x000150000 - 0x00644ffff [Data] (1584 clusters) > > OK. > > 0: Header. no change. > Data: 512b > Zeroes: 63.5KiB > > 1: Reftable. No change. > Data: 512b > Zeroes: 63.5KiB > > Cluster 2: Almost the same.... ref[5] (i.e. the sixth) through ref[20] > have been decremented, but everything else remains at refcount of 01. > Still takes up the same amount of space at the sector granularity level. > Data: 3.5KiB > Zeroes: 60.5KiB > > Cluster 3: L1 table. No change. > Data: 512B > Zeroes: 63.5KiB > > Cluster 4: L2 table > Here, the first 16 data clusters have been modified to zero cluster > pointers: 0x0000000000000001, everything else remains defined as it was. > Data: 5KiB > Zeroes: 59KiB > > Clusters 5-20 inclusive: non-zero data now discarded and considered > unused. 1MiB. makes sense. > > Clusters 21-end: non-zero, used data. 1584 clusters; 101376KiB; 99MiB > > My Tallies: > > Metadata: 10KiB > Metadata Zeroes: 310KiB > Undefined Data: 1MiB > Data: 99MiB > > Your Tallies: > 'used-data': 99.3MiB (101683.2KiB) > 'used-zeroes': 60KiB > 'unused-data': 1MiB > > Subtracting out the 99MiB of data surely accounted for correctly here; > you are counting about 0.3MiB + 60KiB of used data for presumably the > metadata regions; ~367.2KiB. > > Looks like your counts are something like: > metadata: 260KiB (0.25MiB ... ~0.3 with rounding, OK) > metadata-zeroes: 60KiB > > So it's probably just counting what is and isn't zeroes a little less > aggressively than I am doing. To what extent or how, I don't know. Maybe > it depends on the underlying filesystem: > > jhuston@probe ~> qemu-img map -f raw X > Offset Length Mapped to File > 0 0x31000 0 X > 0x40000 0x10000 0x40000 X > 0x150000 0x6300000 0x150000 X > > Looks like a hole from 0x31000 to 0x40000, 60KiB in the metadata region, > so that's probably it. > > Then there's a hole from 0x50000 to 0x150000, 1MiB, so that's unused data. > > Hey, interesting, the discarded data that would be read as zeroes is > still defined by the QCOW2 schema so that's "unused-zeroes" whereas the > zero space in the metadata is only counted as such because of the sparse > gap, so that's used-zero. OK, I think I'm starting to get what these > numbers mean. > >>>> +# @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. >> > Unallocated in what sense, exactly? Do you have an example for qcow2? > I'm sorry that i still don't quite follow :\ > >>>> +# @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. >> > Alright, let me see if I have this straight... > > used-data: Normal data. We are standing on terra-firma. > used-zero: Data that is defined to be zeroes in some way. > > (Does not necessarily include data clusters if they were not actually > zeroed out, I think. May not include regions that ARE zero, even if they > are literally zero, because the driver may not especially recognize them > as such. Anything marked as zero will DEFINITELY be zero, though. Yes?) > > used-discarded: I'm not actually sure in this case. > > used-overrun: Data that is defined to exist, but appears to fall outside > of or beyond EOF. Appears to happen with qcow2 metadata before any > writes occur. > > unused-data: Normal data, but not in-use by the schema anywhere. Leaked > clusters and the like, effectively. > > unused-zero: Similar to the above, but definitely zeroes. > > unused-discarded: Not really sure. yes, something like this. again, -data, -zero and -discarded are just corresponding to return value of bdrv_get_block_status(bs->file), if status & BDRV_BLOCK_DATA it is -data else if status & BDRV_BLOCK_ZERO it is -zero (should be holes for raw) else it is -discarded (impossible for raw) end > >>>> +# @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 check >>>> >>> Sorry for the dumb questions. >> Don't worry) >> >>> --John >>
On 06/29/2017 02:59 AM, Vladimir Sementsov-Ogievskiy wrote: > 29.06.2017 03:15, John Snow wrote: >> >> Alright, let me see if I have this straight... >> >> used-data: Normal data. We are standing on terra-firma. >> used-zero: Data that is defined to be zeroes in some way. >> >> (Does not necessarily include data clusters if they were not actually >> zeroed out, I think. May not include regions that ARE zero, even if they >> are literally zero, because the driver may not especially recognize them >> as such. Anything marked as zero will DEFINITELY be zero, though. Yes?) >> >> used-discarded: I'm not actually sure in this case. >> >> used-overrun: Data that is defined to exist, but appears to fall outside >> of or beyond EOF. Appears to happen with qcow2 metadata before any >> writes occur. >> >> unused-data: Normal data, but not in-use by the schema anywhere. Leaked >> clusters and the like, effectively. >> >> unused-zero: Similar to the above, but definitely zeroes. >> >> unused-discarded: Not really sure. > > yes, something like this. again, -data, -zero and -discarded are just > corresponding to return value of bdrv_get_block_status(bs->file), > > if status & BDRV_BLOCK_DATA > it is -data > else if status & BDRV_BLOCK_ZERO > it is -zero (should be holes for raw) > else > it is -discarded (impossible for raw) > end > Understood, but I was not too clear on the exact nature of block status, so I needed to clarify. I'm a lot clearer now, thanks.
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 <vsementsov@virtuozzo.com> > --- > 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: > +# > +# > +# Allocation relations between format file and underlying protocol file. > +# All fields are in bytes. > +# I guess this is a relation in the sense that the format differentiates between used-unused and the protocol differentiates between data-zero-trim which gives us the 2D matrix, showing a relation between "two" files. I find the use of the word "file" here a bit of a misdirection, though, as qcow2 (or any other format) in this sense is not a file but rather a schema used for interpreting data, and the file itself belongs solely to the protocol. I might suggest phrasing this as ... "Allocation information of an underlying protocol file, as partitioned by a format driver's utilization of said allocations." Maybe that's too wordy. Eric? > +# 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 "format file" seems misleading for similar reasons to my objection above, which is that the format doesn't have a file, exactly. It's an abstract schema. "It's up to the format how to interpret these types" is also a bit too vague to help inform readers what the types mean, IMO. Here's an attempt: "Allocations may be considered either used or unused by the format driver interpreting those allocations. It is at the discretion of the format driver (e.g. qcow2) which regions of its backing storage are considered in-use or not." I'm trying to clarify that it is not up to the qcow2 driver what "used" or "unused" *means* but rather that only the qcow2 driver itself can know which segments are used or unused, as these are semantic distinctions that belong to the format driver layer. Does that make sense? That's the spirit of my suggestion. > +# 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). > +# "For now, the only format driver supporting this feature is Qcow2 which is a 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." (Your original description is actually pretty clear.) I might add some further examples to illustrate the abstraction boundary we're targeting: "Examples of unused allocations for the Qcow2 format are leaked clusters, pre-allocated clusters, and recently freed clusters." > +# For the underlying file there are native block-status types of the portions: How about "underlying protocol file" or "underlying storage protocol" or something that uses the word "protocol" to make it very clear about when we're talking about a format (qcow2) and when we're talking about the storage/protocol file itself (raw posix) > +# - data: allocated data ACK. My favorite kind of data. Easy to understand for idiots like me. > +# - zero: read-as-zero holes This is not *necessarily* a hole, at the discretion of the protocol. Depending on how we've backed the qcow2 we might not actually know how the zeroes are stored, or if they are stored. All we know is that the storage protocol here knows that this data happens to be zero. I find the usage of "hole" here to be misleading, as it suggests naturally either filesystem sparse allocations (which is correct, incidentally) but also qcow2 holes, which doesn't have anything to do with zeroes, necessarily. > +# - discarded: not allocated This might be OK; I don't have a better suggestion. "not allocated" is again protocol-dependent, but I can't think of a better way to phrase this, actually... > +# 4th additional type is 'overrun', which is for the format file portions beyond > +# the end of the underlying file. > +# "Which is data referenced by the format driver located beyond EOF of the protocol file." The key thing I am trying to illustrate in the phrase is that the format file specifies or alludes to the existence of data that is beyond the EOF for the protocol file. I think -- though I cannot prove -- that this is almost certainly a special case of read-as-zero. If that is the case, perhaps we could mention as much. An example here would be really illustrative: "For example, a partially allocated cluster at the end of a QCOW2 file, where Qcow2 generally operates on complete clusters." > +# So, the fields are: > +# > +# @used-data: used by the format file and backed by data in the underlying file > +# > +# @used-zero: used by the format file and backed by a hole in the underlying > +# file > +# Maybe "backed by zeroes in the underlying file; which may be a filesystem hole for e.g. POSIX files." > +# @used-discarded: used by the format file but actually unallocated in the > +# underlying file > +# Which would almost certainly be an error, right? Mentioning as much might be good. > +# @used-overrun: used by the format file beyond the end of the underlying file > +# Which may or may not be an error, depending on how the protocol file (for the format driver?) handles reads to areas out of bounds. > +# @unused-data: allocated data in the underlying file not used by the format > +# > +# @unused-zero: holes in the underlying file not used by the format file > +# > +# @unused-discarded: unallocated areas in the underlying 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 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 check > All of my suggestions here are purely on phrasings. The mechanics of this patch are now clear to me and I think it is useful information to have in qemu. Thanks for putting up with my questions!
On 06/29/2017 07:27 PM, 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 <vsementsov@virtuozzo.com> >> --- >> +# >> +# Allocation relations between format file and underlying protocol file. >> +# All fields are in bytes. >> +# > > I guess this is a relation in the sense that the format differentiates > between used-unused and the protocol differentiates between > data-zero-trim which gives us the 2D matrix, showing a relation between > "two" files. > > I find the use of the word "file" here a bit of a misdirection, though, > as qcow2 (or any other format) in this sense is not a file but rather a > schema used for interpreting data, and the file itself belongs solely to > the protocol. > > I might suggest phrasing this as ... > > "Allocation information of an underlying protocol file, as partitioned > by a format driver's utilization of said allocations." > > Maybe that's too wordy. Eric? No, that actually sounds quite reasonable! We're stating how much of the protocol BDS is allocated, and subdividing those allocations by how much the format layer is using the allocation (where the format layer usage includes metadata not visible to the guest). Our division of information will let us spot both directions of mismatches: - the format layer is not currently referencing anything from the protocol layer, but the protocol layer doesn't have a hole (for example, possible in qcow2 both after a guest trims clusters, or when you delete an internal snapshot - and where we don't punch holes when freeing clusters) - the format layer is currently spending bytes to reference arbitrary data from the protocol layer, but the protocol layer has a hole, so the format layer could use a more compact representation (for example, qcow2 has an allocated cluster and assumes it is arbitrary data, but the underlying protocol layer has a hole, and bdrv_get_block_status returns a combination of BDRV_BLOCK_DATA|BDRV_BLOCK_ZERO thanks to its recursive calls to both BDS) > > Here's an attempt: > > "Allocations may be considered either used or unused by the format > driver interpreting those allocations. It is at the discretion of the > format driver (e.g. qcow2) which regions of its backing storage are > considered in-use or not." > > I'm trying to clarify that it is not up to the qcow2 driver what "used" > or "unused" *means* but rather that only the qcow2 driver itself can > know which segments are used or unused, as these are semantic > distinctions that belong to the format driver layer. Does that make sense? Works for me. > "Which is data referenced by the format driver located beyond EOF of the > protocol file." > > The key thing I am trying to illustrate in the phrase is that the format > file specifies or alludes to the existence of data that is beyond the > EOF for the protocol file. > > I think -- though I cannot prove -- that this is almost certainly a > special case of read-as-zero. If that is the case, perhaps we could > mention as much. Yes, all format drivers that allow use of clusters beyond EOF of the underlying protocol treat that additional data as read-as-zero (at any rate, bdrv_co_get_block_status() already has that interpretation, because it adds BDRV_BLOCK_ZERO to the return value). > > An example here would be really illustrative: > > "For example, a partially allocated cluster at the end of a QCOW2 file, > where Qcow2 generally operates on complete clusters." > >> +# So, the fields are: >> +# >> +# @used-data: used by the format file and backed by data in the underlying file >> +# >> +# @used-zero: used by the format file and backed by a hole in the underlying >> +# file >> +# > > Maybe "backed by zeroes in the underlying file; which may be a > filesystem hole for e.g. POSIX files." "for e.g." is redundant use of "for" (I remember a mnemonic for e.g. as "example given" [better than looking up the actual Latin abbreviation]; but idiomatically, it's easiest to pronounce "e.g." as "for example"). > >> +# @used-discarded: used by the format file but actually unallocated in the >> +# underlying file >> +# > > Which would almost certainly be an error, right? Mentioning as much > might be good. Not necessarily an error, if it corresponds to a section that the guest has done a TRIM operation on, but where we did not have the means to punch a hole in the protocol layer. The semantics of guest TRIM is that the data can no longer be reliably read, making it weaker (and thus easier to implement) than explicitly writing things to zero (although writing zeroes can often be sped up by trimming, when you have guarantees on what will be read later). > >> +# @used-overrun: used by the format file beyond the end of the underlying file >> +# > > Which may or may not be an error, depending on how the protocol file > (for the format driver?) handles reads to areas out of bounds. Back to that read-as-zero semantics beyond EOF we mentioned above - as long as the format driver is okay with reads-as-zero content at those offsets, it is not an error. But yeah, if someone truncated the underlying protocol file behind the format layer's back, then it's a data corruption issue (maybe only the metadata, but more likely also the guest-visible data). > >> +# @unused-data: allocated data in the underlying file not used by the format >> +# >> +# @unused-zero: holes in the underlying file not used by the format file >> +# >> +# @unused-discarded: unallocated areas in the underlying 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 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 check >> > > All of my suggestions here are purely on phrasings. The mechanics of > this patch are now clear to me and I think it is useful information to > have in qemu. > > Thanks for putting up with my questions! >
On 06/29/2017 08:45 PM, Eric Blake wrote: > On 06/29/2017 07:27 PM, 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 <vsementsov@virtuozzo.com> >>> --- > >>> +# >>> +# Allocation relations between format file and underlying protocol file. >>> +# All fields are in bytes. >>> +# >> >> I guess this is a relation in the sense that the format differentiates >> between used-unused and the protocol differentiates between >> data-zero-trim which gives us the 2D matrix, showing a relation between >> "two" files. >> >> I find the use of the word "file" here a bit of a misdirection, though, >> as qcow2 (or any other format) in this sense is not a file but rather a >> schema used for interpreting data, and the file itself belongs solely to >> the protocol. >> >> I might suggest phrasing this as ... >> >> "Allocation information of an underlying protocol file, as partitioned >> by a format driver's utilization of said allocations." >> >> Maybe that's too wordy. Eric? > > No, that actually sounds quite reasonable! We're stating how much of the > protocol BDS is allocated, and subdividing those allocations by how much > the format layer is using the allocation (where the format layer usage > includes metadata not visible to the guest). Our division of > information will let us spot both directions of mismatches: > > - the format layer is not currently referencing anything from the > protocol layer, but the protocol layer doesn't have a hole (for example, > possible in qcow2 both after a guest trims clusters, or when you delete > an internal snapshot - and where we don't punch holes when freeing clusters) > > - the format layer is currently spending bytes to reference arbitrary > data from the protocol layer, but the protocol layer has a hole, so the > format layer could use a more compact representation (for example, qcow2 > has an allocated cluster and assumes it is arbitrary data, but the > underlying protocol layer has a hole, and bdrv_get_block_status returns > a combination of BDRV_BLOCK_DATA|BDRV_BLOCK_ZERO thanks to its recursive > calls to both BDS) > >> >> Here's an attempt: >> >> "Allocations may be considered either used or unused by the format >> driver interpreting those allocations. It is at the discretion of the >> format driver (e.g. qcow2) which regions of its backing storage are >> considered in-use or not." >> >> I'm trying to clarify that it is not up to the qcow2 driver what "used" >> or "unused" *means* but rather that only the qcow2 driver itself can >> know which segments are used or unused, as these are semantic >> distinctions that belong to the format driver layer. Does that make sense? > > Works for me. > > >> "Which is data referenced by the format driver located beyond EOF of the >> protocol file." >> >> The key thing I am trying to illustrate in the phrase is that the format >> file specifies or alludes to the existence of data that is beyond the >> EOF for the protocol file. >> >> I think -- though I cannot prove -- that this is almost certainly a >> special case of read-as-zero. If that is the case, perhaps we could >> mention as much. > > Yes, all format drivers that allow use of clusters beyond EOF of the > underlying protocol treat that additional data as read-as-zero (at any > rate, bdrv_co_get_block_status() already has that interpretation, > because it adds BDRV_BLOCK_ZERO to the return value). > >> >> An example here would be really illustrative: >> >> "For example, a partially allocated cluster at the end of a QCOW2 file, >> where Qcow2 generally operates on complete clusters." >> >>> +# So, the fields are: >>> +# >>> +# @used-data: used by the format file and backed by data in the underlying file >>> +# >>> +# @used-zero: used by the format file and backed by a hole in the underlying >>> +# file >>> +# >> >> Maybe "backed by zeroes in the underlying file; which may be a >> filesystem hole for e.g. POSIX files." > > "for e.g." is redundant use of "for" (I remember a mnemonic for e.g. as > "example given" [better than looking up the actual Latin abbreviation]; > but idiomatically, it's easiest to pronounce "e.g." as "for example"). > I surrender. > >> >>> +# @used-discarded: used by the format file but actually unallocated in the >>> +# underlying file >>> +# >> >> Which would almost certainly be an error, right? Mentioning as much >> might be good. > > Not necessarily an error, if it corresponds to a section that the guest > has done a TRIM operation on, but where we did not have the means to > punch a hole in the protocol layer. The semantics of guest TRIM is that > the data can no longer be reliably read, making it weaker (and thus > easier to implement) than explicitly writing things to zero (although > writing zeroes can often be sped up by trimming, when you have > guarantees on what will be read later). > But the data is considered "used" -- if it cannot be reliably read but the format driver expects to be able to read it, is this not inherently a category that signifies a semantic error? Data that is considered "Discarded" by the protocol (we succeeded in passing on the TRIM request from the guest through to the protocol) should almost certainly no longer be considered "used" by the format...? >> >>> +# @used-overrun: used by the format file beyond the end of the underlying file >>> +# >> >> Which may or may not be an error, depending on how the protocol file >> (for the format driver?) handles reads to areas out of bounds. > > Back to that read-as-zero semantics beyond EOF we mentioned above - as > long as the format driver is okay with reads-as-zero content at those > offsets, it is not an error. But yeah, if someone truncated the > underlying protocol file behind the format layer's back, then it's a > data corruption issue (maybe only the metadata, but more likely also the > guest-visible data). > >> >>> +# @unused-data: allocated data in the underlying file not used by the format >>> +# >>> +# @unused-zero: holes in the underlying file not used by the format file >>> +# >>> +# @unused-discarded: unallocated areas in the underlying 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 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 check >>> >> >> All of my suggestions here are purely on phrasings. The mechanics of >> this patch are now clear to me and I think it is useful information to >> have in qemu. >> >> Thanks for putting up with my questions! >> >
On 06/29/2017 07:54 PM, John Snow wrote: >> Not necessarily an error, if it corresponds to a section that the guest >> has done a TRIM operation on, but where we did not have the means to >> punch a hole in the protocol layer. The semantics of guest TRIM is that >> the data can no longer be reliably read, making it weaker (and thus >> easier to implement) than explicitly writing things to zero (although >> writing zeroes can often be sped up by trimming, when you have >> guarantees on what will be read later). >> > > But the data is considered "used" -- if it cannot be reliably read but > the format driver expects to be able to read it, is this not inherently > a category that signifies a semantic error? It's a semantic error if the region belongs to the metadata portion of the format driver, but not necessarily a problem if it belongs to the guest-visible contents. You're right that a guest probably shouldn't read from areas that it trimmed, but since it is possible to do that on bare metal block devices, it is reasonable that a format driver can emulate what happens when a guest reads from trimmed (but unknown-content) clusters. You're also right that qcow2 probably can't get into this situation (qcow2 v3 files always turned guest-trimmed clusters into read-as-zero; and qcow2 v2 files discard the cluster treating it as unused rather than used, thereby deferring to the backing image). It also corresponds somewhat to the behavior you get when putting a qcow2 format on top of a block device (creating qcow2 as a POSIX file gives you some nice assurances from the filesystem that clusters you haven't touched read as zero; but not so with a brand-new qcow2 file on a block device, where reads can be random until the first write) > Data that is considered "Discarded" by the protocol (we succeeded in > passing on the TRIM request from the guest through to the protocol) > should almost certainly no longer be considered "used" by the format...? The qcow2 format doesn't have a way to specifically represent a cluster as discarded in this manner, but other protocols might.
30.06.2017 03:27, 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 <vsementsov@virtuozzo.com> >> --- >> 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: >> +# >> +# >> +# Allocation relations between format file and underlying protocol file. >> +# All fields are in bytes. >> +# > I guess this is a relation in the sense that the format differentiates > between used-unused and the protocol differentiates between > data-zero-trim which gives us the 2D matrix, showing a relation between > "two" files. > > I find the use of the word "file" here a bit of a misdirection, though, > as qcow2 (or any other format) in this sense is not a file but rather a > schema used for interpreting data, and the file itself belongs solely to > the protocol. > > I might suggest phrasing this as ... > > "Allocation information of an underlying protocol file, as partitioned > by a format driver's utilization of said allocations." > > Maybe that's too wordy. Eric? > >> +# 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 > "format file" seems misleading for similar reasons to my objection > above, which is that the format doesn't have a file, exactly. It's an > abstract schema. > > "It's up to the format how to interpret these types" is also a bit too > vague to help inform readers what the types mean, IMO. > > Here's an attempt: > > "Allocations may be considered either used or unused by the format > driver interpreting those allocations. It is at the discretion of the > format driver (e.g. qcow2) which regions of its backing storage are > considered in-use or not." So we are saying about "allocations". But unallocated data may be used/unused too, so, can we call unallocated areas "allocations"? > > I'm trying to clarify that it is not up to the qcow2 driver what "used" > or "unused" *means* but rather that only the qcow2 driver itself can > know which segments are used or unused, as these are semantic > distinctions that belong to the format driver layer. Does that make sense? > > That's the spirit of my suggestion. > >> +# 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). >> +# > "For now, the only format driver supporting this feature is Qcow2 which > is a 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." > > (Your original description is actually pretty clear.) > > I might add some further examples to illustrate the abstraction boundary > we're targeting: > > "Examples of unused allocations for the Qcow2 format are leaked > clusters, pre-allocated clusters, and recently freed clusters." > >> +# For the underlying file there are native block-status types of the portions: > How about "underlying protocol file" or "underlying storage protocol" or > something that uses the word "protocol" to make it very clear about when > we're talking about a format (qcow2) and when we're talking about the > storage/protocol file itself (raw posix) > >> +# - data: allocated data > ACK. My favorite kind of data. Easy to understand for idiots like me. > >> +# - zero: read-as-zero holes > This is not *necessarily* a hole, at the discretion of the protocol. > Depending on how we've backed the qcow2 we might not actually know how > the zeroes are stored, or if they are stored. All we know is that the > storage protocol here knows that this data happens to be zero. > > I find the usage of "hole" here to be misleading, as it suggests > naturally either filesystem sparse allocations (which is correct, > incidentally) but also qcow2 holes, which doesn't have anything to do > with zeroes, necessarily. > >> +# - discarded: not allocated > This might be OK; I don't have a better suggestion. "not allocated" is > again protocol-dependent, but I can't think of a better way to phrase > this, actually... > >> +# 4th additional type is 'overrun', which is for the format file portions beyond >> +# the end of the underlying file. >> +# > "Which is data referenced by the format driver located beyond EOF of the > protocol file." > > The key thing I am trying to illustrate in the phrase is that the format > file specifies or alludes to the existence of data that is beyond the > EOF for the protocol file. > > I think -- though I cannot prove -- that this is almost certainly a > special case of read-as-zero. If that is the case, perhaps we could > mention as much. > > An example here would be really illustrative: > > "For example, a partially allocated cluster at the end of a QCOW2 file, > where Qcow2 generally operates on complete clusters." > >> +# So, the fields are: >> +# >> +# @used-data: used by the format file and backed by data in the underlying file >> +# >> +# @used-zero: used by the format file and backed by a hole in the underlying >> +# file >> +# > Maybe "backed by zeroes in the underlying file; which may be a > filesystem hole for e.g. POSIX files." > >> +# @used-discarded: used by the format file but actually unallocated in the >> +# underlying file >> +# > Which would almost certainly be an error, right? Mentioning as much > might be good. > >> +# @used-overrun: used by the format file beyond the end of the underlying file >> +# > Which may or may not be an error, depending on how the protocol file > (for the format driver?) handles reads to areas out of bounds. > >> +# @unused-data: allocated data in the underlying file not used by the format >> +# >> +# @unused-zero: holes in the underlying file not used by the format file >> +# >> +# @unused-discarded: unallocated areas in the underlying 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 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 check >> > All of my suggestions here are purely on phrasings. The mechanics of > this patch are now clear to me and I think it is useful information to > have in qemu. > > Thanks for putting up with my questions!
12.07.2017 18:18, Vladimir Sementsov-Ogievskiy wrote: > 30.06.2017 03:27, 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 <vsementsov@virtuozzo.com> >>> --- >>> 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: >>> +# >>> +# >>> +# Allocation relations between format file and underlying protocol >>> file. >>> +# All fields are in bytes. >>> +# >> I guess this is a relation in the sense that the format differentiates >> between used-unused and the protocol differentiates between >> data-zero-trim which gives us the 2D matrix, showing a relation between >> "two" files. >> >> I find the use of the word "file" here a bit of a misdirection, though, >> as qcow2 (or any other format) in this sense is not a file but rather a >> schema used for interpreting data, and the file itself belongs solely to >> the protocol. >> >> I might suggest phrasing this as ... >> >> "Allocation information of an underlying protocol file, as partitioned >> by a format driver's utilization of said allocations." >> >> Maybe that's too wordy. Eric? >> >>> +# 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 >> "format file" seems misleading for similar reasons to my objection >> above, which is that the format doesn't have a file, exactly. It's an >> abstract schema. >> >> "It's up to the format how to interpret these types" is also a bit too >> vague to help inform readers what the types mean, IMO. >> >> Here's an attempt: >> >> "Allocations may be considered either used or unused by the format >> driver interpreting those allocations. It is at the discretion of the >> format driver (e.g. qcow2) which regions of its backing storage are >> considered in-use or not." > > So we are saying about "allocations". But unallocated data may be > used/unused too, so, > can we call unallocated areas "allocations"? John? Note: we can add this with x- prefix or something like this if this simplifies things (and adjust doc later). > >> >> I'm trying to clarify that it is not up to the qcow2 driver what "used" >> or "unused" *means* but rather that only the qcow2 driver itself can >> know which segments are used or unused, as these are semantic >> distinctions that belong to the format driver layer. Does that make >> sense? >> >> That's the spirit of my suggestion. >> >>> +# 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). >>> +# >> "For now, the only format driver supporting this feature is Qcow2 which >> is a 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." >> >> (Your original description is actually pretty clear.) >> >> I might add some further examples to illustrate the abstraction boundary >> we're targeting: >> >> "Examples of unused allocations for the Qcow2 format are leaked >> clusters, pre-allocated clusters, and recently freed clusters." >> >>> +# For the underlying file there are native block-status types of >>> the portions: >> How about "underlying protocol file" or "underlying storage protocol" or >> something that uses the word "protocol" to make it very clear about when >> we're talking about a format (qcow2) and when we're talking about the >> storage/protocol file itself (raw posix) >> >>> +# - data: allocated data >> ACK. My favorite kind of data. Easy to understand for idiots like me. >> >>> +# - zero: read-as-zero holes >> This is not *necessarily* a hole, at the discretion of the protocol. >> Depending on how we've backed the qcow2 we might not actually know how >> the zeroes are stored, or if they are stored. All we know is that the >> storage protocol here knows that this data happens to be zero. >> >> I find the usage of "hole" here to be misleading, as it suggests >> naturally either filesystem sparse allocations (which is correct, >> incidentally) but also qcow2 holes, which doesn't have anything to do >> with zeroes, necessarily. >> >>> +# - discarded: not allocated >> This might be OK; I don't have a better suggestion. "not allocated" is >> again protocol-dependent, but I can't think of a better way to phrase >> this, actually... >> >>> +# 4th additional type is 'overrun', which is for the format file >>> portions beyond >>> +# the end of the underlying file. >>> +# >> "Which is data referenced by the format driver located beyond EOF of the >> protocol file." >> >> The key thing I am trying to illustrate in the phrase is that the format >> file specifies or alludes to the existence of data that is beyond the >> EOF for the protocol file. >> >> I think -- though I cannot prove -- that this is almost certainly a >> special case of read-as-zero. If that is the case, perhaps we could >> mention as much. >> >> An example here would be really illustrative: >> >> "For example, a partially allocated cluster at the end of a QCOW2 file, >> where Qcow2 generally operates on complete clusters." >> >>> +# So, the fields are: >>> +# >>> +# @used-data: used by the format file and backed by data in the >>> underlying file >>> +# >>> +# @used-zero: used by the format file and backed by a hole in the >>> underlying >>> +# file >>> +# >> Maybe "backed by zeroes in the underlying file; which may be a >> filesystem hole for e.g. POSIX files." >> >>> +# @used-discarded: used by the format file but actually unallocated >>> in the >>> +# underlying file >>> +# >> Which would almost certainly be an error, right? Mentioning as much >> might be good. >> >>> +# @used-overrun: used by the format file beyond the end of the >>> underlying file >>> +# >> Which may or may not be an error, depending on how the protocol file >> (for the format driver?) handles reads to areas out of bounds. >> >>> +# @unused-data: allocated data in the underlying file not used by >>> the format >>> +# >>> +# @unused-zero: holes in the underlying file not used by the format >>> file >>> +# >>> +# @unused-discarded: unallocated areas in the underlying 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 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 check >>> >> All of my suggestions here are purely on phrasings. The mechanics of >> this patch are now clear to me and I think it is useful information to >> have in qemu. >> >> Thanks for putting up with my questions! > >
On 07/12/2017 11:18 AM, Vladimir Sementsov-Ogievskiy wrote: > 30.06.2017 03:27, 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 <vsementsov@virtuozzo.com> >>> --- >>> 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: >>> +# >>> +# >>> +# Allocation relations between format file and underlying protocol >>> file. >>> +# All fields are in bytes. >>> +# >> I guess this is a relation in the sense that the format differentiates >> between used-unused and the protocol differentiates between >> data-zero-trim which gives us the 2D matrix, showing a relation between >> "two" files. >> >> I find the use of the word "file" here a bit of a misdirection, though, >> as qcow2 (or any other format) in this sense is not a file but rather a >> schema used for interpreting data, and the file itself belongs solely to >> the protocol. >> >> I might suggest phrasing this as ... >> >> "Allocation information of an underlying protocol file, as partitioned >> by a format driver's utilization of said allocations." >> >> Maybe that's too wordy. Eric? >> >>> +# 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 >> "format file" seems misleading for similar reasons to my objection >> above, which is that the format doesn't have a file, exactly. It's an >> abstract schema. >> >> "It's up to the format how to interpret these types" is also a bit too >> vague to help inform readers what the types mean, IMO. >> >> Here's an attempt: >> >> "Allocations may be considered either used or unused by the format >> driver interpreting those allocations. It is at the discretion of the >> format driver (e.g. qcow2) which regions of its backing storage are >> considered in-use or not." > > So we are saying about "allocations". But unallocated data may be > used/unused too, so, > can we call unallocated areas "allocations"? > You're right, "allocation" may imply something that is extant, but these are more like regions ... Uh; "Regions" may be considered either used or unused? or "Regions of the underlying protocol file may be considered used or unused by the format driver interpreting these regions." Something along these lines, perhaps?
28.07.2017 00:23, John Snow wrote: > > > On 07/12/2017 11:18 AM, Vladimir Sementsov-Ogievskiy wrote: >> 30.06.2017 03:27, 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 <vsementsov@virtuozzo.com> >>>> --- >>>> 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: >>>> +# >>>> +# >>>> +# Allocation relations between format file and underlying protocol >>>> file. >>>> +# All fields are in bytes. >>>> +# >>> I guess this is a relation in the sense that the format differentiates >>> between used-unused and the protocol differentiates between >>> data-zero-trim which gives us the 2D matrix, showing a relation between >>> "two" files. >>> >>> I find the use of the word "file" here a bit of a misdirection, though, >>> as qcow2 (or any other format) in this sense is not a file but rather a >>> schema used for interpreting data, and the file itself belongs >>> solely to >>> the protocol. >>> >>> I might suggest phrasing this as ... >>> >>> "Allocation information of an underlying protocol file, as partitioned >>> by a format driver's utilization of said allocations." >>> >>> Maybe that's too wordy. Eric? >>> >>>> +# 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 >>> "format file" seems misleading for similar reasons to my objection >>> above, which is that the format doesn't have a file, exactly. It's an >>> abstract schema. >>> >>> "It's up to the format how to interpret these types" is also a bit too >>> vague to help inform readers what the types mean, IMO. >>> >>> Here's an attempt: >>> >>> "Allocations may be considered either used or unused by the format >>> driver interpreting those allocations. It is at the discretion of the >>> format driver (e.g. qcow2) which regions of its backing storage are >>> considered in-use or not." >> >> So we are saying about "allocations". But unallocated data may be >> used/unused too, so, >> can we call unallocated areas "allocations"? >> > > You're right, "allocation" may imply something that is extant, but > these are more like regions ... > > Uh; > > "Regions" may be considered either used or unused? > > or > > "Regions of the underlying protocol file may be considered used or > unused by the format driver interpreting these regions." > > Something along these lines, perhaps? This is OK I think.
On 07/27/2017 04:23 PM, John Snow wrote: >>> >>> "Allocations may be considered either used or unused by the format >>> driver interpreting those allocations. It is at the discretion of the >>> format driver (e.g. qcow2) which regions of its backing storage are >>> considered in-use or not." >> >> So we are saying about "allocations". But unallocated data may be >> used/unused too, so, >> can we call unallocated areas "allocations"? >> > > You're right, "allocation" may imply something that is extant, but these > are more like regions ... Even 'extent' might have a connotation of something reserved; other related words like 'block' are bad (a block of a block device?). > > Uh; > > "Regions" may be considered either used or unused? > > or > > "Regions of the underlying protocol file may be considered used or > unused by the format driver interpreting these regions." So this is one of the better variations I've seen, and works for me.
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: +# +# +# Allocation relations between format file and underlying protocol file. +# All fields are in bytes. +# +# 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). +# +# 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 +# +# @used-zero: used by the format file and backed by a hole in the underlying +# file +# +# @used-discarded: used by the format file but actually unallocated in the +# underlying file +# +# @used-overrun: used by the format file beyond the end of the underlying file +# +# @unused-data: allocated data in the underlying file not used by the format +# +# @unused-zero: holes in the underlying file not used by the format file +# +# @unused-discarded: unallocated areas in the underlying 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 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 check
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 <vsementsov@virtuozzo.com> --- block.c | 16 ++++++++++++++ include/block/block.h | 3 +++ include/block/block_int.h | 2 ++ qapi/block-core.json | 55 +++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 76 insertions(+)