On 05/21/2017 09:21 AM, Denis V. Lunev wrote: > qemu-img create -f qcow2 1.img 64G > qemu-io -c "write -P 0x32 0 64k" 1.img > results in > 324 -rw-r--r-- 1 den den 393216 May 21 16:48 1.img > Subsequent > qemu-io -c "write -z 0 64k" 1.img > qemu-io -c "write -P 0x32 0 64k" 1.img > results in > 388 -rw-r--r-- 1 den den 458752 May 21 16:50 1.img > which looks like we have 1 cluster leaked. > > Indeed, qcow2_co_pwrite_zeroes calls qcow2_zero_clusters/zero_single_l2, > which does not update refcount for the host cluster and keep the offset > as used. Later on handle_copied() does not take into account > QCOW2_CLUSTER_ZERO type of the cluster.
NACK. We've already fixed this upstream, at commit 564a6b693. $ ./qemu-img create -f qcow2 1.img 64g Formatting '1.img', fmt=qcow2 size=68719476736 encryption=off cluster_size=65536 lazy_refcounts=off refcount_bits=16 $ ./qemu-io -c 'w -P 0x32 0 64k' 1.img wrote 65536/65536 bytes at offset 0 64 KiB, 1 ops; 0.0410 sec (1.524 MiB/sec and 24.3902 ops/sec) $ ls -l 1.img -rw-r--r--. 1 eblake eblake 393216 May 22 06:35 1.img $ ./qemu-io -c 'w -z 0 64k' 1.img wrote 65536/65536 bytes at offset 0 64 KiB, 1 ops; 0.0055 sec (11.345 MiB/sec and 181.5211 ops/sec) $ ./qemu-io -c 'w -P 0x32 0 64k' 1.img wrote 65536/65536 bytes at offset 0 64 KiB, 1 ops; 0.0160 sec (3.903 MiB/sec and 62.4415 ops/sec) $ ls -l 1.img -rw-r--r--. 1 eblake eblake 393216 May 22 06:35 1.img As it is, your patch doesn't apply to master. And even if it did, your patch breaks semantics - we CANNOT discard clusters that must read back as zeroes. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
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