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authorVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>2020-05-28 12:43:59 +0300
committerMax Reitz <mreitz@redhat.com>2020-07-06 10:32:38 +0200
commit2c060c0f50220bebabacccb8e321df049cca602e (patch)
tree235970fa1d626a9374579a18c27a2798087872f9 /util/bitmap.c
parent2ea0332f427e3c6582a6c82130814c0d4c9ceb40 (diff)
block/vpc: return ZERO block-status when appropriate
In case when get_image_offset() returns -1, we do zero out the corresponding chunk of qiov. So, this should be reported as ZERO. Note that this changes visible output of "qemu-img map --output=json" and "qemu-io -c map" commands. For qemu-img map, the change is obvious: we just mark as zero what is really zero. For qemu-io it's less obvious: what was unallocated now is allocated. There is an inconsistency in understanding of unallocated regions in Qemu: backing-supporting format-drivers return 0 block-status to report go-to-backing logic for this area. Some protocol-drivers (iscsi) return 0 to report fs-unallocated-non-zero status (i.e., don't occupy space on disk, read result is undefined). BDRV_BLOCK_ALLOCATED is defined as something more close to go-to-backing logic. Still it is calculated as ZERO | DATA, so 0 from iscsi is treated as unallocated. It doesn't influence backing-chain behavior, as iscsi can't have backing file. But it does influence "qemu-io -c map". We should solve this inconsistency at some future point. Now, let's just make backing-not-supporting format drivers (vdi in the previous patch and vpc now) to behave more like backing-supporting drivers and not report 0 block-status. More over, returning ZERO status is absolutely valid thing, and again, corresponds to how the other format-drivers (backing-supporting) work. After block-status update, it never reports 0, so setting unallocated_blocks_are_zero doesn't make sense (as the only user of it is bdrv_co_block_status and it checks unallocated_blocks_are_zero only for unallocated areas). Drop it. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20200528094405.145708-5-vsementsov@virtuozzo.com> [mreitz: qemu-io -c map as used by iotest 146 now reports everything as allocated; in order to make the test do something useful, we use qemu-img map --output=json now] Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'util/bitmap.c')
0 files changed, 0 insertions, 0 deletions