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Re: [Qemu-block] [PATCH 5/7] qcow2: use byte-based read in qcow2_decompr
From: |
Alberto Garcia |
Subject: |
Re: [Qemu-block] [PATCH 5/7] qcow2: use byte-based read in qcow2_decompress_cluster |
Date: |
Tue, 06 Nov 2018 14:53:05 +0100 |
User-agent: |
Notmuch/0.18.2 (http://notmuchmail.org) Emacs/24.4.1 (i586-pc-linux-gnu) |
On Thu 01 Nov 2018 07:27:36 PM CET, Vladimir Sementsov-Ogievskiy wrote:
> diff --git a/block/qcow2.c b/block/qcow2.c
> index e9d24b801e..950b9f7ec6 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -3956,14 +3956,15 @@ fail:
> int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
> {
> BDRVQcow2State *s = bs->opaque;
> - int ret, csize, nb_csectors, sector_offset;
> + int ret, csize, nb_csectors;
> uint64_t coffset;
> + struct iovec iov;
> + QEMUIOVector local_qiov;
>
> coffset = cluster_offset & s->cluster_offset_mask;
> if (s->cluster_cache_offset != coffset) {
> nb_csectors = ((cluster_offset >> s->csize_shift) & s->csize_mask) +
> 1;
> - sector_offset = coffset & 511;
> - csize = nb_csectors * 512 - sector_offset;
> + csize = nb_csectors * 512 - (coffset & 511);
>
> /* Allocate buffers on first decompress operation, most images are
> * uncompressed and the memory overhead can be avoided. The buffers
> @@ -3981,14 +3982,17 @@ int qcow2_decompress_cluster(BlockDriverState *bs,
> uint64_t cluster_offset)
> s->cluster_cache = g_malloc(s->cluster_size);
> }
>
> + iov.iov_base = s->cluster_data;
> + iov.iov_len = csize;
> + qemu_iovec_init_external(&local_qiov, &iov, 1);
> +
> BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED);
> - ret = bdrv_read(bs->file, coffset >> 9, s->cluster_data,
> - nb_csectors);
> + ret = bdrv_co_preadv(bs->file, coffset, csize, &local_qiov,
> 0);
I think you should annotate the function with coroutine_fn or use
bdrv_pread() instead.
Berto
- [Qemu-block] [PATCH 0/7] qcow2 decompress in threads, Vladimir Sementsov-Ogievskiy, 2018/11/01
- [Qemu-block] [PATCH 5/7] qcow2: use byte-based read in qcow2_decompress_cluster, Vladimir Sementsov-Ogievskiy, 2018/11/01
- Re: [Qemu-block] [PATCH 5/7] qcow2: use byte-based read in qcow2_decompress_cluster,
Alberto Garcia <=
- [Qemu-block] [PATCH 7/7] qcow2: do decompression in threads, Vladimir Sementsov-Ogievskiy, 2018/11/01
- [Qemu-block] [PATCH 2/7] qcow2: make more generic interface for qcow2_compress, Vladimir Sementsov-Ogievskiy, 2018/11/01
- [Qemu-block] [PATCH 4/7] qcow2: refactor decompress_buffer, Vladimir Sementsov-Ogievskiy, 2018/11/01
- [Qemu-block] [PATCH 3/7] qcow2: move decompression from qcow2-cluster.c to qcow2.c, Vladimir Sementsov-Ogievskiy, 2018/11/01