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From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: Alberto Garcia <berto@igalia.com>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Cc: Kevin Wolf <kwolf@redhat.com>,
	Anton Nefedov <anton.nefedov@virtuozzo.com>,
	Denis Lunev <den@virtuozzo.com>,
	"qemu-block@nongnu.org" <qemu-block@nongnu.org>,
	Max Reitz <mreitz@redhat.com>
Subject: Re: [RFC PATCH v2 01/26] qcow2: Add calculate_l2_meta()
Date: Mon, 28 Oct 2019 12:50:54 +0000	[thread overview]
Message-ID: <81fcd087-d4f7-173d-e6cc-53f59dbd2d45@virtuozzo.com> (raw)
In-Reply-To: <22820af5867124e4fdf3d0cb74b99f31edc1b37f.1572125022.git.berto@igalia.com>

27.10.2019 0:25, Alberto Garcia wrote:
> handle_alloc() creates a QCowL2Meta structure in order to update the
> image metadata and perform the necessary copy-on-write operations.
> 
> This patch moves that code to a separate function so it can be used
> from other places.
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>
> ---
>   block/qcow2-cluster.c | 76 +++++++++++++++++++++++++++++--------------
>   1 file changed, 52 insertions(+), 24 deletions(-)
> 
> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
> index 8982b7b762..6c1dcdc781 100644
> --- a/block/qcow2-cluster.c
> +++ b/block/qcow2-cluster.c
> @@ -1019,6 +1019,55 @@ void qcow2_alloc_cluster_abort(BlockDriverState *bs, QCowL2Meta *m)
>                           QCOW2_DISCARD_NEVER);
>   }
>   
> +/*
> + * For a given write request, create a new QCowL2Meta structure and
> + * add it to @m.
> + *
> + * @host_offset points to the beginning of the first cluster.
> + *
> + * @guest_offset and @bytes indicate the offset and length of the
> + * request.
> + *
> + * If @keep_old is true it means that the clusters were already
> + * allocated and will be overwritten. If false then the clusters are
> + * new and we have to decrease the reference count of the old ones.
> + */
> +static void calculate_l2_meta(BlockDriverState *bs, uint64_t host_offset,
> +                              uint64_t guest_offset, uint64_t bytes,
> +                              QCowL2Meta **m, bool keep_old)
> +{
> +    BDRVQcow2State *s = bs->opaque;
> +    unsigned cow_start_from = 0;
> +    unsigned cow_start_to = offset_into_cluster(s, guest_offset);
> +    unsigned cow_end_from = cow_start_to + bytes;
> +    unsigned cow_end_to = ROUND_UP(cow_end_from, s->cluster_size);

New code is easier to read!

Interesting, seems QEMU_ALIGN_UP is more popular.. But comment above ROUND_UP
makes sense in using it here..

> +    unsigned nb_clusters = size_to_clusters(s, cow_end_from);
> +    QCowL2Meta *old_m = *m;
> +
> +    *m = g_malloc0(sizeof(**m));
> +    **m = (QCowL2Meta) {
> +        .next           = old_m,
> +
> +        .alloc_offset   = host_offset,
> +        .offset         = start_of_cluster(s, guest_offset),
> +        .nb_clusters    = nb_clusters,
> +
> +        .keep_old_clusters = keep_old,
> +
> +        .cow_start = {
> +            .offset     = cow_start_from,
> +            .nb_bytes   = cow_start_to - cow_start_from,
> +        },
> +        .cow_end = {
> +            .offset     = cow_end_from,
> +            .nb_bytes   = cow_end_to - cow_end_from,
> +        },
> +    };
> +
> +    qemu_co_queue_init(&(*m)->dependent_requests);
> +    QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
> +}
> +
>   /*
>    * Returns the number of contiguous clusters that can be used for an allocating
>    * write, but require COW to be performed (this includes yet unallocated space,
> @@ -1417,35 +1466,14 @@ static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset,
>       uint64_t requested_bytes = *bytes + offset_into_cluster(s, guest_offset);
>       int avail_bytes = nb_clusters << s->cluster_bits;
>       int nb_bytes = MIN(requested_bytes, avail_bytes);
> -    QCowL2Meta *old_m = *m;
> -
> -    *m = g_malloc0(sizeof(**m));
> -
> -    **m = (QCowL2Meta) {
> -        .next           = old_m,
> -
> -        .alloc_offset   = alloc_cluster_offset,
> -        .offset         = start_of_cluster(s, guest_offset),
> -        .nb_clusters    = nb_clusters,
> -
> -        .keep_old_clusters  = keep_old_clusters,
> -
> -        .cow_start = {
> -            .offset     = 0,
> -            .nb_bytes   = offset_into_cluster(s, guest_offset),
> -        },
> -        .cow_end = {
> -            .offset     = nb_bytes,

hmm this logic is changed.. after the patch, it would be not nb_bytes, but

offset_into_cluster(s, guest_offset) + MIN(*bytes, nb_bytes - offset_into_cluster(s, guest_offset))

> -            .nb_bytes   = avail_bytes - nb_bytes,
> -        },
> -    };
> -    qemu_co_queue_init(&(*m)->dependent_requests);
> -    QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
>   
>       *host_offset = alloc_cluster_offset + offset_into_cluster(s, guest_offset);
>       *bytes = MIN(*bytes, nb_bytes - offset_into_cluster(s, guest_offset));
>       assert(*bytes != 0);
>   
> +    calculate_l2_meta(bs, alloc_cluster_offset, guest_offset, *bytes,
> +                      m, keep_old_clusters);
> +
>       return 1;
>   
>   fail:
> 


-- 
Best regards,
Vladimir

  reply	other threads:[~2019-10-28 13:35 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 [this message]
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
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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