From: Eric Blake <eblake@redhat.com>
To: Alberto Garcia <berto@igalia.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 v8 30/34] qcow2: Add prealloc field to QCowL2Meta
Date: Wed, 10 Jun 2020 11:44:49 -0500 [thread overview]
Message-ID: <a1626701-1a7e-ea18-4813-56e9dd72c8c8@redhat.com> (raw)
In-Reply-To: <259e53cff2911316e427c40001801004e6b4257d.1591801197.git.berto@igalia.com>
On 6/10/20 10:03 AM, Alberto Garcia wrote:
> This field allows us to indicate that the L2 metadata update does not
> come from a write request with actual data but from a preallocation
> request.
>
> For traditional images this does not make any difference, but for
> images with extended L2 entries this means that the clusters are
> allocated normally in the L2 table but individual subclusters are
> marked as unallocated.
>
> This will allow preallocating images that have a backing file.
>
> There is one special case: when we resize an existing image we can
> also request that the new clusters are preallocated. If the image
> already had a backing file then we have to hide any possible stale
> data and zero out the new clusters (see commit 955c7d6687 for more
> details).
>
> In this case the subclusters cannot be left as unallocated so the L2
> bitmap must be updated.
>
> Signed-off-by: Alberto Garcia <berto@igalia.com>
> ---
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
next prev parent reply other threads:[~2020-06-10 16:45 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-10 15:02 [PATCH v8 00/34] Add subcluster allocation to qcow2 Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 01/34] qcow2: Make Qcow2AioTask store the full host offset Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 02/34] qcow2: Convert qcow2_get_cluster_offset() into qcow2_get_host_offset() Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 03/34] qcow2: Add calculate_l2_meta() Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 04/34] qcow2: Split cluster_needs_cow() out of count_cow_clusters() Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 05/34] qcow2: Process QCOW2_CLUSTER_ZERO_ALLOC clusters in handle_copied() Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 06/34] qcow2: Add get_l2_entry() and set_l2_entry() Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 07/34] qcow2: Document the Extended L2 Entries feature Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 08/34] qcow2: Add dummy has_subclusters() function Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 09/34] qcow2: Add subcluster-related fields to BDRVQcow2State Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 10/34] qcow2: Add offset_to_sc_index() Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 11/34] qcow2: Add offset_into_subcluster() and size_to_subclusters() Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 12/34] qcow2: Add l2_entry_size() Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 13/34] qcow2: Update get/set_l2_entry() and add get/set_l2_bitmap() Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 14/34] qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type() Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 15/34] qcow2: Add qcow2_get_subcluster_range_type() Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 16/34] qcow2: Add qcow2_cluster_is_allocated() Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 17/34] qcow2: Add cluster type parameter to qcow2_get_host_offset() Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 18/34] qcow2: Replace QCOW2_CLUSTER_* with QCOW2_SUBCLUSTER_* Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 19/34] qcow2: Handle QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 20/34] qcow2: Add subcluster support to calculate_l2_meta() Alberto Garcia
2020-06-10 15:02 ` [PATCH v8 21/34] qcow2: Add subcluster support to qcow2_get_host_offset() Alberto Garcia
2020-06-10 15:03 ` [PATCH v8 22/34] qcow2: Add subcluster support to zero_in_l2_slice() Alberto Garcia
2020-06-10 15:03 ` [PATCH v8 23/34] qcow2: Add subcluster support to discard_in_l2_slice() Alberto Garcia
2020-06-10 15:03 ` [PATCH v8 24/34] qcow2: Add subcluster support to check_refcounts_l2() Alberto Garcia
2020-06-10 15:03 ` [PATCH v8 25/34] qcow2: Update L2 bitmap in qcow2_alloc_cluster_link_l2() Alberto Garcia
2020-06-10 15:03 ` [PATCH v8 26/34] qcow2: Clear the L2 bitmap when allocating a compressed cluster Alberto Garcia
2020-06-10 15:03 ` [PATCH v8 27/34] qcow2: Add subcluster support to handle_alloc_space() Alberto Garcia
2020-06-10 15:03 ` [PATCH v8 28/34] qcow2: Add subcluster support to qcow2_co_pwrite_zeroes() Alberto Garcia
2020-06-10 15:03 ` [PATCH v8 29/34] qcow2: Add subcluster support to qcow2_measure() Alberto Garcia
2020-06-10 15:03 ` [PATCH v8 30/34] qcow2: Add prealloc field to QCowL2Meta Alberto Garcia
2020-06-10 16:44 ` Eric Blake [this message]
2020-06-10 15:03 ` [PATCH v8 31/34] qcow2: Add the 'extended_l2' option and the QCOW2_INCOMPAT_EXTL2 bit Alberto Garcia
2020-06-10 15:03 ` [PATCH v8 32/34] qcow2: Allow preallocation and backing files if extended_l2 is set Alberto Garcia
2020-06-10 19:37 ` Eric Blake
2020-06-10 15:03 ` [PATCH v8 33/34] qcow2: Assert that expand_zero_clusters_in_l1() does not support subclusters Alberto Garcia
2020-06-10 19:43 ` Eric Blake
2020-06-11 13:24 ` Alberto Garcia
2020-06-11 14:36 ` Eric Blake
2020-06-10 15:03 ` [PATCH v8 34/34] iotests: Add tests for qcow2 images with extended L2 entries Alberto Garcia
2020-06-10 20:24 ` Eric Blake
2020-06-10 20:07 ` [PATCH v8 00/34] Add subcluster allocation to qcow2 Eric Blake
2020-06-10 21:45 ` no-reply
2020-06-10 22:52 ` no-reply
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