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Re: [Qemu-block] [PATCH v3 18/39] qcow2: Refactor get_cluster_table()
From: |
Max Reitz |
Subject: |
Re: [Qemu-block] [PATCH v3 18/39] qcow2: Refactor get_cluster_table() |
Date: |
Wed, 31 Jan 2018 21:11:48 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 |
On 2018-01-26 15:59, Alberto Garcia wrote:
> After the previous patch we're now always using l2_load() in
> get_cluster_table() regardless of whether a new L2 table has to be
> allocated or not.
>
> This patch refactors that part of the code to use one single l2_load()
> call.
>
> Signed-off-by: Alberto Garcia <address@hidden>
> ---
> block/qcow2-cluster.c | 21 +++++++--------------
> 1 file changed, 7 insertions(+), 14 deletions(-)
>
> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
> index 2a53c1dc5f..0c0cab85e8 100644
> --- a/block/qcow2-cluster.c
> +++ b/block/qcow2-cluster.c
> @@ -695,15 +695,7 @@ static int get_cluster_table(BlockDriverState *bs,
> uint64_t offset,
> return -EIO;
> }
>
> - /* seek the l2 table of the given l2 offset */
> -
> - if (s->l1_table[l1_index] & QCOW_OFLAG_COPIED) {
> - /* load the l2 table in memory */
> - ret = l2_load(bs, offset, l2_offset, &l2_table);
> - if (ret < 0) {
> - return ret;
> - }
> - } else {
> + if (!(s->l1_table[l1_index] & QCOW_OFLAG_COPIED)) {
> /* First allocate a new L2 table (and do COW if needed) */
> ret = l2_allocate(bs, l1_index);
> if (ret < 0) {
> @@ -719,11 +711,12 @@ static int get_cluster_table(BlockDriverState *bs,
> uint64_t offset,
> /* Get the offset of the newly-allocated l2 table */
> l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
> assert(offset_into_cluster(s, l2_offset) == 0);
> - /* Load the l2 table in memory */
> - ret = l2_load(bs, offset, l2_offset, &l2_table);
> - if (ret < 0) {
> - return ret;
> - }
> + }
> +
> + /* load the l2 table in memory */
> + ret = l2_load(bs, offset, l2_offset, &l2_table);
> + if (ret < 0) {
> + return ret;
> }
I'd pull the l2_offset assignment (and alignment check) down below the
QCOW_OFLAG_COPIED check, saving us another two lines (!!1!) which we
could then spend on an
assert(s->l1_table[l1_index] & QCOW_OFLAG_COPIED);
Max
>
> /* find the cluster offset for the given disk offset */
>
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- [Qemu-block] [PATCH v3 00/39] Allow configuring the qcow2 L2 cache entry size, Alberto Garcia, 2018/01/26
- [Qemu-block] [PATCH v3 16/39] qcow2: Prepare l2_allocate() for adding L2 slice support, Alberto Garcia, 2018/01/26
- [Qemu-block] [PATCH v3 02/39] qcow2: Add table size field to Qcow2Cache, Alberto Garcia, 2018/01/26
- [Qemu-block] [PATCH v3 15/39] qcow2: Update l2_load() to support L2 slices, Alberto Garcia, 2018/01/26
- [Qemu-block] [PATCH v3 18/39] qcow2: Refactor get_cluster_table(), Alberto Garcia, 2018/01/26
- [Qemu-block] [PATCH v3 03/39] qcow2: Remove BDS parameter from qcow2_cache_get_table_addr(), Alberto Garcia, 2018/01/26
- [Qemu-block] [PATCH v3 12/39] qcow2: Add offset_to_l1_index(), Alberto Garcia, 2018/01/26
- [Qemu-block] [PATCH v3 19/39] qcow2: Update get_cluster_table() to support L2 slices, Alberto Garcia, 2018/01/26
- [Qemu-block] [PATCH v3 37/39] iotests: Test valid values of l2-cache-entry-size, Alberto Garcia, 2018/01/26
- [Qemu-block] [PATCH v3 39/39] iotests: Add l2-cache-entry-size to iotest 137, Alberto Garcia, 2018/01/26