Re: [Qemu-devel] [PATCHv4 04/11] consolidate qemu_iovec_memset{, _skip}() into single function and use existing iov_memset()

[Anthony Liguori <anthony@codemonkey.ws>]

On 03/15/2012 04:00 PM, Michael Tokarev wrote:
> This patch combines two functions into one, and replaces
> the implementation with already existing iov_memset() from
> iov.c.
>
> The new prototype of qemu_iovec_memset():
>    size_t qemu_iovec_memset(qiov, size_t offset, int fillc, size_t bytes)
> It is different from former qemu_iovec_memset_skip(), and
> I want to make other functions to be consistent with it
> too: first how much to skip, second what, and 3rd how many
> of it.  It also returns actual number of bytes filled in,
> which may be less than the requested `bytes' if qiov is
> smaller than offset+bytes, in the same way iov_memset()
> does.
>
> While at it, use utility function iov_memset() from
> iov.h in posix-aio-compat.c, where qiov was used.
>
> Signed-off-by: Michael Tokarev<mjt@tls.msk.ru>

Please CC Kevin at least when making block changes.

It looks fine to me but would appreciate Kevin/Stefan taking a look too.

Regards,

Anthony Liguori

> ---
>   block/qcow2.c      |    4 ++--
>   block/qed.c        |    4 ++--
>   cutils.c           |   44 ++++----------------------------------------
>   linux-aio.c        |    4 ++--
>   posix-aio-compat.c |    8 +++-----
>   qemu-common.h      |    5 ++---
>   6 files changed, 15 insertions(+), 54 deletions(-)
>
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 7aece65..941a6a9 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -407,7 +407,7 @@ int qcow2_backing_read1(BlockDriverState *bs, QEMUIOVector *qiov,
>       else
>           n1 = bs->total_sectors - sector_num;
>
> -    qemu_iovec_memset_skip(qiov, 0, 512 * (nb_sectors - n1), 512 * n1);
> +    qemu_iovec_memset(qiov, 512 * n1, 0, 512 * (nb_sectors - n1));
>
>       return n1;
>   }
> @@ -467,7 +467,7 @@ static coroutine_fn int qcow2_co_readv(BlockDriverState *bs, int64_t sector_num,
>                   }
>               } else {
>                   /* Note: in this case, no need to wait */
> -                qemu_iovec_memset(&hd_qiov, 0, 512 * cur_nr_sectors);
> +                qemu_iovec_memset(&hd_qiov, 0, 0, 512 * cur_nr_sectors);
>               }
>           } else if (cluster_offset&  QCOW_OFLAG_COMPRESSED) {
>               /* add AIO support for compressed blocks ? */
> diff --git a/block/qed.c b/block/qed.c
> index a041d31..6f9325b 100644
> --- a/block/qed.c
> +++ b/block/qed.c
> @@ -738,7 +738,7 @@ static void qed_read_backing_file(BDRVQEDState *s, uint64_t pos,
>       /* Zero all sectors if reading beyond the end of the backing file */
>       if (pos>= backing_length ||
>           pos + qiov->size>  backing_length) {
> -        qemu_iovec_memset(qiov, 0, qiov->size);
> +        qemu_iovec_memset(qiov, 0, 0, qiov->size);
>       }
>
>       /* Complete now if there are no backing file sectors to read */
> @@ -1253,7 +1253,7 @@ static void qed_aio_read_data(void *opaque, int ret,
>
>       /* Handle zero cluster and backing file reads */
>       if (ret == QED_CLUSTER_ZERO) {
> -        qemu_iovec_memset(&acb->cur_qiov, 0, acb->cur_qiov.size);
> +        qemu_iovec_memset(&acb->cur_qiov, 0, 0, acb->cur_qiov.size);
>           qed_aio_next_io(acb, 0);
>           return;
>       } else if (ret != QED_CLUSTER_FOUND) {
> diff --git a/cutils.c b/cutils.c
> index af308cd..0ddf4c7 100644
> --- a/cutils.c
> +++ b/cutils.c
> @@ -26,6 +26,7 @@
>   #include<math.h>
>
>   #include "qemu_socket.h"
> +#include "iov.h"
>
>   void pstrcpy(char *buf, int buf_size, const char *str)
>   {
> @@ -260,47 +261,10 @@ void qemu_iovec_from_buffer(QEMUIOVector *qiov, const void *buf, size_t count)
>       }
>   }
>
> -void qemu_iovec_memset(QEMUIOVector *qiov, int c, size_t count)
> +size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset,
> +                         int fillc, size_t bytes)
>   {
> -    size_t n;
> -    int i;
> -
> -    for (i = 0; i<  qiov->niov&&  count; ++i) {
> -        n = MIN(count, qiov->iov[i].iov_len);
> -        memset(qiov->iov[i].iov_base, c, n);
> -        count -= n;
> -    }
> -}
> -
> -void qemu_iovec_memset_skip(QEMUIOVector *qiov, int c, size_t count,
> -                            size_t skip)
> -{
> -    int i;
> -    size_t done;
> -    void *iov_base;
> -    uint64_t iov_len;
> -
> -    done = 0;
> -    for (i = 0; (i<  qiov->niov)&&  (done != count); i++) {
> -        if (skip>= qiov->iov[i].iov_len) {
> -            /* Skip the whole iov */
> -            skip -= qiov->iov[i].iov_len;
> -            continue;
> -        } else {
> -            /* Skip only part (or nothing) of the iov */
> -            iov_base = (uint8_t*) qiov->iov[i].iov_base + skip;
> -            iov_len = qiov->iov[i].iov_len - skip;
> -            skip = 0;
> -        }
> -
> -        if (done + iov_len>  count) {
> -            memset(iov_base, c, count - done);
> -            break;
> -        } else {
> -            memset(iov_base, c, iov_len);
> -        }
> -        done += iov_len;
> -    }
> +    return iov_memset(qiov->iov, qiov->niov, offset, fillc, bytes);
>   }
>
>   /*
> diff --git a/linux-aio.c b/linux-aio.c
> index d2fc2e7..5a46c13 100644
> --- a/linux-aio.c
> +++ b/linux-aio.c
> @@ -64,8 +64,8 @@ static void qemu_laio_process_completion(struct qemu_laio_state *s,
>           } else if (ret>= 0) {
>               /* Short reads mean EOF, pad with zeros. */
>               if (laiocb->is_read) {
> -                qemu_iovec_memset_skip(laiocb->qiov, 0,
> -                    laiocb->qiov->size - ret, ret);
> +                qemu_iovec_memset(laiocb->qiov, ret, 0,
> +                    laiocb->qiov->size - ret);
>               } else {
>                   ret = -EINVAL;
>               }
> diff --git a/posix-aio-compat.c b/posix-aio-compat.c
> index d311d13..1ab4a18 100644
> --- a/posix-aio-compat.c
> +++ b/posix-aio-compat.c
> @@ -29,6 +29,7 @@
>   #include "qemu-common.h"
>   #include "trace.h"
>   #include "block_int.h"
> +#include "iov.h"
>
>   #include "block/raw-posix-aio.h"
>
> @@ -351,11 +352,8 @@ static void *aio_thread(void *unused)
>               if (ret>= 0&&  ret<  aiocb->aio_nbytes&&  aiocb->common.bs->growable) {
>                   /* A short read means that we have reached EOF. Pad the buffer
>                    * with zeros for bytes after EOF. */
> -                QEMUIOVector qiov;
> -
> -                qemu_iovec_init_external(&qiov, aiocb->aio_iov,
> -                                         aiocb->aio_niov);
> -                qemu_iovec_memset_skip(&qiov, 0, aiocb->aio_nbytes - ret, ret);
> +                iov_memset(aiocb->aio_iov, aiocb->aio_niov, ret,
> +                           0, aiocb->aio_nbytes - ret);
>
>                   ret = aiocb->aio_nbytes;
>               }
> diff --git a/qemu-common.h b/qemu-common.h
> index b0fdf5c..3c556c8 100644
> --- a/qemu-common.h
> +++ b/qemu-common.h
> @@ -344,9 +344,8 @@ void qemu_iovec_destroy(QEMUIOVector *qiov);
>   void qemu_iovec_reset(QEMUIOVector *qiov);
>   void qemu_iovec_to_buffer(QEMUIOVector *qiov, void *buf);
>   void qemu_iovec_from_buffer(QEMUIOVector *qiov, const void *buf, size_t count);
> -void qemu_iovec_memset(QEMUIOVector *qiov, int c, size_t count);
> -void qemu_iovec_memset_skip(QEMUIOVector *qiov, int c, size_t count,
> -                            size_t skip);
> +size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset,
> +                         int fillc, size_t bytes);
>
>   bool buffer_is_zero(const void *buf, size_t len);
>