Re: [Qemu-devel] [PATCH v2 4/5] block/nvme: add support for write zeros

[Fam Zheng <fam@euphon.net>]

On Wed, 04/17 22:53, Maxim Levitsky wrote:
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
>  block/nvme.c         | 69 +++++++++++++++++++++++++++++++++++++++++++-
>  block/trace-events   |  1 +
>  include/block/nvme.h | 19 +++++++++++-
>  3 files changed, 87 insertions(+), 2 deletions(-)
> 
> diff --git a/block/nvme.c b/block/nvme.c
> index 0b1da54574..35b925899f 100644
> --- a/block/nvme.c
> +++ b/block/nvme.c
> @@ -109,6 +109,8 @@ typedef struct {
>      uint64_t max_transfer;
>      bool plugged;
>  
> +    bool supports_write_zeros;
> +
>      CoMutex dma_map_lock;
>      CoQueue dma_flush_queue;
>  
> @@ -457,6 +459,10 @@ static void nvme_identify(BlockDriverState *bs, int namespace, Error **errp)
>      s->max_transfer = MIN_NON_ZERO(s->max_transfer,
>                            s->page_size / sizeof(uint64_t) * s->page_size);
>  
> +
> +

Too many blank lines here.

> +    s->supports_write_zeros = (idctrl->oncs & NVME_ONCS_WRITE_ZEROS) != 0;
> +
>      memset(resp, 0, 4096);
>  
>      cmd.cdw10 = 0;
> @@ -469,6 +475,11 @@ static void nvme_identify(BlockDriverState *bs, int namespace, Error **errp)
>      s->nsze = le64_to_cpu(idns->nsze);
>      lbaf = &idns->lbaf[NVME_ID_NS_FLBAS_INDEX(idns->flbas)];
>  
> +    if (NVME_ID_NS_DLFEAT_WRITE_ZEROS(idns->dlfeat) &&
> +            NVME_ID_NS_DLFEAT_READ_BEHAVIOR(idns->dlfeat) ==
> +                    NVME_ID_NS_DLFEAT_READ_BEHAVIOR_ZEROS)
> +        bs->supported_write_flags |= BDRV_REQ_MAY_UNMAP;
> +
>      if (lbaf->ms) {
>          error_setg(errp, "Namespaces with metadata are not yet supported");
>          goto out;
> @@ -763,6 +774,8 @@ static int nvme_file_open(BlockDriverState *bs, QDict *options, int flags,
>      int ret;
>      BDRVNVMeState *s = bs->opaque;
>  
> +    bs->supported_write_flags = BDRV_REQ_FUA;
> +
>      opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
>      qemu_opts_absorb_qdict(opts, options, &error_abort);
>      device = qemu_opt_get(opts, NVME_BLOCK_OPT_DEVICE);
> @@ -791,7 +804,6 @@ static int nvme_file_open(BlockDriverState *bs, QDict *options, int flags,
>              goto fail;
>          }
>      }
> -    bs->supported_write_flags = BDRV_REQ_FUA;
>      return 0;
>  fail:
>      nvme_close(bs);
> @@ -1080,6 +1092,58 @@ static coroutine_fn int nvme_co_flush(BlockDriverState *bs)
>  }
>  
>  
> +static coroutine_fn int nvme_co_pwrite_zeroes(BlockDriverState *bs,
> +    int64_t offset, int bytes, BdrvRequestFlags flags)
> +{
> +    BDRVNVMeState *s = bs->opaque;
> +    NVMeQueuePair *ioq = s->queues[1];
> +    NVMeRequest *req;
> +
> +    if (!s->supports_write_zeros) {
> +        return -ENOTSUP;
> +    }

Local variables declaration below statements is not allowed as per coding style.

> +
> +    uint32_t cdw12 = ((bytes >> s->blkshift) - 1) & 0xFFFF;
> +
> +    NvmeCmd cmd = {
> +        .opcode = NVME_CMD_WRITE_ZEROS,
> +        .nsid = cpu_to_le32(s->nsid),
> +        .cdw10 = cpu_to_le32((offset >> s->blkshift) & 0xFFFFFFFF),
> +        .cdw11 = cpu_to_le32(((offset >> s->blkshift) >> 32) & 0xFFFFFFFF),
> +    };
> +
> +    NVMeCoData data = {
> +        .ctx = bdrv_get_aio_context(bs),
> +        .ret = -EINPROGRESS,
> +    };
> +
> +    if (flags & BDRV_REQ_MAY_UNMAP) {
> +        cdw12 |= (1 << 25);
> +    }
> +
> +    if (flags & BDRV_REQ_FUA) {
> +        cdw12 |= (1 << 30);
> +    }
> +
> +    cmd.cdw12 = cpu_to_le32(cdw12);
> +
> +    trace_nvme_write_zeros(s, offset, bytes, flags);
> +    assert(s->nr_queues > 1);
> +    req = nvme_get_free_req(ioq);
> +    assert(req);
> +
> +    nvme_submit_command(s, ioq, req, &cmd, nvme_rw_cb, &data);
> +
> +    data.co = qemu_coroutine_self();
> +    while (data.ret == -EINPROGRESS) {
> +        qemu_coroutine_yield();
> +    }
> +
> +    trace_nvme_rw_done(s, true, offset, bytes, data.ret);
> +    return data.ret;
> +}
> +
> +
>  static int nvme_reopen_prepare(BDRVReopenState *reopen_state,
>                                 BlockReopenQueue *queue, Error **errp)
>  {
> @@ -1184,6 +1248,9 @@ static BlockDriver bdrv_nvme = {
>  
>      .bdrv_co_preadv           = nvme_co_preadv,
>      .bdrv_co_pwritev          = nvme_co_pwritev,
> +
> +    .bdrv_co_pwrite_zeroes    = nvme_co_pwrite_zeroes,
> +
>      .bdrv_co_flush_to_disk    = nvme_co_flush,
>      .bdrv_reopen_prepare      = nvme_reopen_prepare,
>  
> diff --git a/block/trace-events b/block/trace-events
> index 7335a42540..943a58569f 100644
> --- a/block/trace-events
> +++ b/block/trace-events
> @@ -144,6 +144,7 @@ nvme_submit_command_raw(int c0, int c1, int c2, int c3, int c4, int c5, int c6,
>  nvme_handle_event(void *s) "s %p"
>  nvme_poll_cb(void *s) "s %p"
>  nvme_prw_aligned(void *s, int is_write, uint64_t offset, uint64_t bytes, int flags, int niov) "s %p is_write %d offset %"PRId64" bytes %"PRId64" flags %d niov %d"
> +nvme_write_zeros(void *s, uint64_t offset, uint64_t bytes, int flags) "s %p offset %"PRId64" bytes %"PRId64" flags %d"
>  nvme_qiov_unaligned(const void *qiov, int n, void *base, size_t size, int align) "qiov %p n %d base %p size 0x%zx align 0x%x"
>  nvme_prw_buffered(void *s, uint64_t offset, uint64_t bytes, int niov, int is_write) "s %p offset %"PRId64" bytes %"PRId64" niov %d is_write %d"
>  nvme_rw_done(void *s, int is_write, uint64_t offset, uint64_t bytes, int ret) "s %p is_write %d offset %"PRId64" bytes %"PRId64" ret %d"
> diff --git a/include/block/nvme.h b/include/block/nvme.h
> index 0eae6f9f15..edf8e90557 100644
> --- a/include/block/nvme.h
> +++ b/include/block/nvme.h
> @@ -653,12 +653,29 @@ typedef struct NvmeIdNs {
>      uint8_t     mc;
>      uint8_t     dpc;
>      uint8_t     dps;
> -    uint8_t     res30[98];
> +
> +    uint8_t     nmic;
> +    uint8_t     rescap;
> +    uint8_t     fpi;
> +    uint8_t     dlfeat;
> +
> +    uint8_t     res30[94];
>      NvmeLBAF    lbaf[16];
>      uint8_t     res192[192];
>      uint8_t     vs[3712];
>  } NvmeIdNs;
>  
> +
> +/*Deallocate Logical Block Features*/
> +#define NVME_ID_NS_DLFEAT_GUARD_CRC(dlfeat)       ((dlfeat) & 0x10)
> +#define NVME_ID_NS_DLFEAT_WRITE_ZEROS(dlfeat)     ((dlfeat) & 0x04)
> +
> +#define NVME_ID_NS_DLFEAT_READ_BEHAVIOR(dlfeat)     ((dlfeat) & 0x3)
> +#define NVME_ID_NS_DLFEAT_READ_BEHAVIOR_UNDEFINED   0
> +#define NVME_ID_NS_DLFEAT_READ_BEHAVIOR_ZEROS       1
> +#define NVME_ID_NS_DLFEAT_READ_BEHAVIOR_ONES        2
> +
> +
>  #define NVME_ID_NS_NSFEAT_THIN(nsfeat)      ((nsfeat & 0x1))
>  #define NVME_ID_NS_FLBAS_EXTENDED(flbas)    ((flbas >> 4) & 0x1)
>  #define NVME_ID_NS_FLBAS_INDEX(flbas)       ((flbas & 0xf))
> -- 
> 2.17.2
>