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From: Alberto Garcia <berto@igalia.com>
To: Max Reitz <mreitz@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
	Anton Nefedov <anton.nefedov@virtuozzo.com>,
	qemu-block@nongnu.org,
	Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
	"Denis V . Lunev" <den@openvz.org>
Subject: Re: [RFC PATCH v2 10/26] qcow2: Update get/set_l2_entry() and add get/set_l2_bitmap()
Date: Thu, 14 Nov 2019 14:57:54 +0100	[thread overview]
Message-ID: <w51y2wief19.fsf@maestria.local.igalia.com> (raw)
In-Reply-To: <012198da-55cd-b176-5cb0-0002fc3b92b1@redhat.com>

On Wed 30 Oct 2019 05:55:04 PM CET, Max Reitz wrote:
>> This patch also adds the get/set_l2_bitmap() functions that are used
>> to access the bitmaps. For convenience, these functions are no-ops
>> when used in traditional qcow2 images.
>
> Granted, I haven’t seen the following patches yet, but if these
> functions are indeed called for images that don’t have subclusters,
> shouldn’t they return 0x0*0f*f then? (i.e. everything allocated)
>
> If they aren’t, they should probably just abort().  Well,
> set_l2_bitmap() should probably always abort() if there aren’t any
> subclusters.

Yeah, set_l2_bitmap() should abort (I had this changed already).

About get_l2_bitmap() ... I decided not to abort for convenience, for
cases like this one:

    uint64_t l2_entry = get_l2_entry(s, l2_slice, l2_index);
    uint64_t l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index);
    type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc);

Here the value of l2_bitmap is going to be ignored anyway so it doesn't
matter what we return, but perhaps for consistency we should return
QCOW_OFLAG_SUB_ALLOC(0), which means that the first (and only, in this
case) subcluster is allocated.

Berto


  reply	other threads:[~2019-11-14 13:58 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-26 21:25 [RFC PATCH v2 00/26] Add subcluster allocation to qcow2 Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 01/26] qcow2: Add calculate_l2_meta() Alberto Garcia
2019-10-28 12:50   ` Vladimir Sementsov-Ogievskiy
2019-10-30 15:56     ` Alberto Garcia
2019-10-30 12:04   ` Max Reitz
2019-10-30 16:02     ` Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 02/26] qcow2: Split cluster_needs_cow() out of count_cow_clusters() Alberto Garcia
2019-10-28 13:55   ` Vladimir Sementsov-Ogievskiy
2019-10-26 21:25 ` [RFC PATCH v2 03/26] qcow2: Process QCOW2_CLUSTER_ZERO_ALLOC clusters in handle_copied() Alberto Garcia
2019-10-30 14:24   ` Max Reitz
2019-11-13 14:25     ` Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 04/26] qcow2: Add get_l2_entry() and set_l2_entry() Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 05/26] qcow2: Document the Extended L2 Entries feature Alberto Garcia
2019-10-30 16:23   ` Max Reitz
2019-10-30 22:38     ` Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 06/26] qcow2: Add dummy has_subclusters() function Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 07/26] qcow2: Add subcluster-related fields to BDRVQcow2State Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 08/26] qcow2: Add offset_to_sc_index() Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 09/26] qcow2: Add l2_entry_size() Alberto Garcia
2019-10-30 16:47   ` Max Reitz
2019-10-26 21:25 ` [RFC PATCH v2 10/26] qcow2: Update get/set_l2_entry() and add get/set_l2_bitmap() Alberto Garcia
2019-10-30 16:55   ` Max Reitz
2019-11-14 13:57     ` Alberto Garcia [this message]
2019-10-26 21:25 ` [RFC PATCH v2 11/26] qcow2: Add qcow2_get_subcluster_type() Alberto Garcia
2019-11-04 12:35   ` Max Reitz
2019-11-04 15:01     ` Max Reitz
2019-10-26 21:25 ` [RFC PATCH v2 12/26] qcow2: Handle QCOW2_CLUSTER_UNALLOCATED_SUBCLUSTER Alberto Garcia
2019-11-04 12:57   ` Max Reitz
2019-11-04 13:03     ` Alberto Garcia
2019-11-04 13:10       ` Max Reitz
2019-11-07 14:44         ` Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 13/26] qcow2: Add subcluster support to calculate_l2_meta() Alberto Garcia
2019-11-04 14:21   ` Max Reitz
2019-11-08 15:18     ` Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 14/26] qcow2: Add subcluster support to qcow2_get_cluster_offset() Alberto Garcia
2019-11-04 14:58   ` Max Reitz
2019-11-08 15:42     ` Alberto Garcia
2019-11-11  8:42       ` Max Reitz
2019-10-26 21:25 ` [RFC PATCH v2 15/26] qcow2: Add subcluster support to zero_in_l2_slice() Alberto Garcia
2019-11-04 15:04   ` Max Reitz
2019-11-04 15:10     ` Max Reitz
2019-11-14 15:31       ` Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 16/26] qcow2: Add subcluster support to discard_in_l2_slice() Alberto Garcia
2019-11-04 15:07   ` Max Reitz
2019-11-14 15:33     ` Alberto Garcia
2019-11-14 16:22       ` Max Reitz
2019-10-26 21:25 ` [RFC PATCH v2 17/26] qcow2: Add subcluster support to check_refcounts_l2() Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 18/26] qcow2: Add subcluster support to expand_zero_clusters_in_l1() Alberto Garcia
2019-11-05 11:05   ` Max Reitz
2019-11-14 15:43     ` Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 19/26] qcow2: Fix offset calculation in handle_dependencies() Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 20/26] qcow2: Update L2 bitmap in qcow2_alloc_cluster_link_l2() Alberto Garcia
2019-11-05 11:43   ` Max Reitz
2019-11-14 16:30     ` Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 21/26] qcow2: Clear the L2 bitmap when allocating a compressed cluster Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 22/26] qcow2: Add subcluster support to handle_alloc_space() Alberto Garcia
2019-11-05 12:05   ` Max Reitz
2019-10-26 21:25 ` [RFC PATCH v2 23/26] qcow2: Restrict qcow2_co_pwrite_zeroes() to full clusters only Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 24/26] qcow2: Add the 'extended_l2' option and the QCOW2_INCOMPAT_EXTL2 bit Alberto Garcia
2019-11-05 12:47   ` Max Reitz
2019-11-15 13:35     ` Alberto Garcia
2019-10-26 21:25 ` [RFC PATCH v2 25/26] qcow2: Allow preallocation and backing files if extended_l2 is set Alberto Garcia
2019-11-05 13:11   ` Max Reitz
2019-10-26 21:25 ` [RFC PATCH v2 26/26] iotests: Add tests for qcow2 images with extended L2 entries Alberto Garcia
2019-11-05 13:32 ` [RFC PATCH v2 00/26] Add subcluster allocation to qcow2 Max Reitz

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