Re: [Qemu-devel] [PATCH 4/5] ide: add TRIM support

[Kevin Wolf <kwolf@redhat.com>]

Am 01.12.2010 16:35, schrieb Christoph Hellwig:
> Add support for the data set management command, and the TRIM sub function
> in it.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> 
> Index: qemu/hw/ide/core.c
> ===================================================================
> --- qemu.orig/hw/ide/core.c	2010-11-30 23:12:59.513132702 +0100
> +++ qemu/hw/ide/core.c	2010-12-01 12:02:47.347023889 +0100
> @@ -145,6 +145,8 @@ static void ide_identify(IDEState *s)
>      put_le16(p + 66, 120);
>      put_le16(p + 67, 120);
>      put_le16(p + 68, 120);
> +    if (dev && dev->conf.discard_granularity)
> +        put_le16(p + 69, (1 << 14)); /* determinate TRIM behavior */

Braces

>      put_le16(p + 80, 0xf0); /* ata3 -> ata6 supported */
>      put_le16(p + 81, 0x16); /* conforms to ata5 */
>      /* 14=NOP supported, 5=WCACHE supported, 0=SMART supported */
> @@ -171,6 +173,8 @@ static void ide_identify(IDEState *s)
>      dev = s->unit ? s->bus->slave : s->bus->master;
>      if (dev && dev->conf.physical_block_size)
>          put_le16(p + 106, 0x6000 | get_physical_block_exp(&dev->conf));
> +    if (dev && dev->conf.discard_granularity)
> +        put_le16(p + 169, 1); /* TRIM support */
>  
>      memcpy(s->identify_data, p, sizeof(s->identify_data));
>      s->identify_set = 1;
> @@ -1788,6 +1792,128 @@ static void ide_clear_hob(IDEBus *bus)
>      bus->ifs[1].select &= ~(1 << 7);
>  }
>  
> +typedef struct TrimAIOCB {
> +    BlockDriverAIOCB common;
> +    QEMUBH *bh;
> +    int ret;
> +} TrimAIOCB;
> +
> +static void trim_aio_cancel(BlockDriverAIOCB *acb)
> +{
> +    TrimAIOCB *iocb = container_of(acb, TrimAIOCB, common);
> +
> +    qemu_bh_delete(iocb->bh);
> +    iocb->bh = NULL;
> +    qemu_aio_release(iocb);
> +}
> +
> +static AIOPool trim_aio_pool = {
> +    .aiocb_size         = sizeof(TrimAIOCB),
> +    .cancel             = trim_aio_cancel,
> +};
> +
> +static void ide_trim_bh_cb(void *opaque)
> +{
> +    TrimAIOCB *iocb = opaque;
> +
> +    iocb->common.cb(iocb->common.opaque, iocb->ret);
> +
> +    qemu_bh_delete(iocb->bh);
> +    iocb->bh = NULL;
> +
> +    qemu_aio_release(iocb);
> +}
> +
> +static BlockDriverAIOCB *ide_issue_trim(BlockDriverState *bs,
> +        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
> +        BlockDriverCompletionFunc *cb, void *opaque)
> +{
> +    TrimAIOCB *iocb;
> +    int i, j, ret;
> +
> +    iocb = qemu_aio_get(&trim_aio_pool, bs, cb, opaque);
> +    iocb->bh = qemu_bh_new(ide_trim_bh_cb, iocb);
> +    iocb->ret = 0;
> +
> +    for (j = 0; j < qiov->niov; j++) {
> +        uint64_t *buffer = qiov->iov[j].iov_base;
> +
> +        for (i = 0; i < qiov->iov[j].iov_len / 8; i++) {
> +            /* 6-byte LBA + 2-byte range per entry */
> +            uint64_t entry = le64_to_cpu(buffer[i]);
> +            uint64_t sector = entry & 0x0000ffffffffffffULL;
> +            uint16_t count = entry >> 48;
> +
> +            if (count == 0)
> +                break;
> +
> +            ret = bdrv_discard(bs, sector * 512, count * 512);
> +            if (!iocb->ret)
> +                iocb->ret = ret;
> +        }
> +    }
> +
> +    qemu_bh_schedule(iocb->bh);
> +
> +    return &iocb->common;
> +}
> +
> +static void ide_trim_dma_cb(void *opaque, int ret)
> +{
> +    BMDMAState *bm = opaque;
> +    IDEState *s = bmdma_active_if(bm);
> +    int n;
> +    int64_t sector_num;
> +
> +    if (ret < 0) {
> +        if (ide_handle_rw_error(s, -ret,  BM_STATUS_DMA_RETRY))
> +            return;

This looks wrong. Wouldn't werror=stop cause the request to be retried
as a write when the VM is resumed?

But having a copy&paste error gives just about right reason to mention
that after read and write this is the third almost unchanged copy of
this code. Eventually we'll want to refactor this.

> +    }
> +
> +    n = s->io_buffer_size >> 9;
> +    sector_num = ide_get_sector(s);
> +    if (n > 0) {
> +        dma_buf_commit(s, 0);
> +        sector_num += n;
> +        ide_set_sector(s, sector_num);
> +        s->nsector -= n;
> +    }
> +
> +    /* end of transfer ? */
> +    if (s->nsector == 0) {
> +        s->status = READY_STAT | SEEK_STAT;
> +        ide_set_irq(s->bus);
> +    eot:
> +        bm->status &= ~BM_STATUS_DMAING;
> +        bm->status |= BM_STATUS_INT;
> +        bm->dma_cb = NULL;
> +        bm->unit = -1;
> +        bm->aiocb = NULL;

You can use ide_dma_set_inactive() here.

While we're at it, do you know why in the eot: case we set
BM_STATUS_INT, but don't actually call ide_set_irq? From what I
understand, those two should always be coupled, but I might be wrong.

Kevin