From: Alberto Garcia <berto@igalia.com>
To: Eric Blake <eblake@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Derek Su <dereksu@qnap.com>,
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
qemu-block@nongnu.org, Max Reitz <mreitz@redhat.com>
Subject: Re: [PATCH v7 28/32] qcow2: Add subcluster support to qcow2_co_pwrite_zeroes()
Date: Fri, 29 May 2020 18:06:40 +0200 [thread overview]
Message-ID: <w51sgfivi7j.fsf@maestria.local.igalia.com> (raw)
In-Reply-To: <0adafac6-15e8-96eb-6c3f-bb9c182fb2d1@redhat.com>
On Thu 28 May 2020 09:11:07 PM CEST, Eric Blake wrote:
>> I think the problem also exists in the current code (without my
>> patches). If you zeroize 10 clusters and the last one is compressed
>> you have to repeat the request after having zeroized 9 clusters.
>
> Hmm. In the pre-patch code, qcow2_co_pwrite_zeroes() calls
> qcow2_cluster_zeroize() which can fail with -ENOTSUP up front, but not
> after the fact. Once it starts the while loop over clusters, its use
> of zero_in_l2_slice() handles compressed clusters just fine;
You're right, complete compressed clusters can always be handled, the
problem is just when there's subclusters.
> But isn't this something we could solve recursively? Instead of
> returning -ENOTSUP, we could have zero_in_l2_slice() call
> bdrv_pwrite_zeroes() on the (sub-)clusters associated with a
> compressed cluster.
I suppose we could, as long as BDRV_REQ_NO_FALLBACK is not used.
Berto
next prev parent reply other threads:[~2020-05-29 16:07 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-25 18:08 [PATCH v7 00/32] Add subcluster allocation to qcow2 Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 01/32] qcow2: Make Qcow2AioTask store the full host offset Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 02/32] qcow2: Convert qcow2_get_cluster_offset() into qcow2_get_host_offset() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 03/32] qcow2: Add calculate_l2_meta() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 04/32] qcow2: Split cluster_needs_cow() out of count_cow_clusters() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 05/32] qcow2: Process QCOW2_CLUSTER_ZERO_ALLOC clusters in handle_copied() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 06/32] qcow2: Add get_l2_entry() and set_l2_entry() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 07/32] qcow2: Document the Extended L2 Entries feature Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 08/32] qcow2: Add dummy has_subclusters() function Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 09/32] qcow2: Add subcluster-related fields to BDRVQcow2State Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 10/32] qcow2: Add offset_to_sc_index() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 11/32] qcow2: Add offset_into_subcluster() and size_to_subclusters() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 12/32] qcow2: Add l2_entry_size() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 13/32] qcow2: Update get/set_l2_entry() and add get/set_l2_bitmap() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 14/32] qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type() Alberto Garcia
2020-05-26 20:32 ` Eric Blake
2020-05-27 9:51 ` Alberto Garcia
2020-05-27 13:27 ` Eric Blake
2020-05-25 18:08 ` [PATCH v7 15/32] qcow2: Add qcow2_get_subcluster_range_type() Alberto Garcia
2020-05-26 21:48 ` Eric Blake
2020-05-25 18:08 ` [PATCH v7 16/32] qcow2: Add qcow2_cluster_is_allocated() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 17/32] qcow2: Add cluster type parameter to qcow2_get_host_offset() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 18/32] qcow2: Replace QCOW2_CLUSTER_* with QCOW2_SUBCLUSTER_* Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 19/32] qcow2: Handle QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 20/32] qcow2: Add subcluster support to calculate_l2_meta() Alberto Garcia
2020-05-27 15:57 ` Eric Blake
2020-05-25 18:08 ` [PATCH v7 21/32] qcow2: Add subcluster support to qcow2_get_host_offset() Alberto Garcia
2020-05-27 16:40 ` Eric Blake
2020-05-25 18:08 ` [PATCH v7 22/32] qcow2: Add subcluster support to zero_in_l2_slice() Alberto Garcia
2020-05-27 16:43 ` Eric Blake
2020-05-25 18:08 ` [PATCH v7 23/32] qcow2: Add subcluster support to discard_in_l2_slice() Alberto Garcia
2020-05-27 16:50 ` Eric Blake
2020-05-25 18:08 ` [PATCH v7 24/32] qcow2: Add subcluster support to check_refcounts_l2() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 25/32] qcow2: Update L2 bitmap in qcow2_alloc_cluster_link_l2() Alberto Garcia
2020-05-27 16:52 ` Eric Blake
2020-05-25 18:08 ` [PATCH v7 26/32] qcow2: Clear the L2 bitmap when allocating a compressed cluster Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 27/32] qcow2: Add subcluster support to handle_alloc_space() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 28/32] qcow2: Add subcluster support to qcow2_co_pwrite_zeroes() Alberto Garcia
2020-05-27 17:58 ` Eric Blake
2020-05-28 15:04 ` Alberto Garcia
2020-05-28 19:11 ` Eric Blake
2020-05-29 16:06 ` Alberto Garcia [this message]
2020-05-25 18:08 ` [PATCH v7 29/32] qcow2: Add subcluster support to qcow2_measure() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 30/32] qcow2: Add the 'extended_l2' option and the QCOW2_INCOMPAT_EXTL2 bit Alberto Garcia
2020-05-27 18:03 ` Eric Blake
2020-05-25 18:08 ` [PATCH v7 31/32] qcow2: Assert that expand_zero_clusters_in_l1() does not support subclusters Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 32/32] iotests: Add tests for qcow2 images with extended L2 entries Alberto Garcia
2020-05-27 18:30 ` Eric Blake
2020-05-29 15:07 ` Alberto Garcia
2020-05-29 15:13 ` Eric Blake
2020-05-26 2:54 ` [PATCH v7 00/32] Add subcluster allocation to qcow2 no-reply
2020-05-26 11:01 ` Alberto Garcia
2020-05-26 5:17 ` no-reply
2020-05-26 5:48 ` no-reply
2020-05-26 6:14 ` no-reply
2020-05-26 8:01 ` no-reply
2020-05-26 10:13 ` no-reply
2020-05-26 13:08 ` no-reply
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