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Date: Fri, 21 Jan 2011 10:16:58 +0100
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] Fix block migration when the device size
	is	not a multiple of 1 MB
References: <1295449188-17877-1-git-send-email-Pierre.Riteau@irisa.fr>
In-Reply-To: <1295449188-17877-1-git-send-email-Pierre.Riteau@irisa.fr>
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To: Pierre Riteau <Pierre.Riteau@irisa.fr>
Cc: qemu-devel@nongnu.org, tamura.yoshiaki@lab.ntt.co.jp

Am 19.01.2011 15:59, schrieb Pierre Riteau:
> b02bea3a85cc939f09aa674a3f1e4f36d418c007 added a check on the return
> value of bdrv_write and aborts migration when it fails. However, if the
> size of the block device to migrate is not a multiple of BLOCK_SIZE
> (currently 1 MB), the last bdrv_write will fail with -EIO.
> 
> Fixed by calling bdrv_write with the correct size of the last block.
> ---
>  block-migration.c |   16 +++++++++++++++-
>  1 files changed, 15 insertions(+), 1 deletions(-)
> 
> diff --git a/block-migration.c b/block-migration.c
> index 1475325..eeb9c62 100644
> --- a/block-migration.c
> +++ b/block-migration.c
> @@ -635,6 +635,8 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
>      int64_t addr;
>      BlockDriverState *bs;
>      uint8_t *buf;
> +    int64_t total_sectors;
> +    int nr_sectors;
>  
>      do {
>          addr = qemu_get_be64(f);
> @@ -656,10 +658,22 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
>                  return -EINVAL;
>              }
>  
> +            total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
> +            if (total_sectors <= 0) {
> +                fprintf(stderr, "Error getting length of block device %s\n", device_name);
> +                return -EINVAL;
> +            }

Can you resend the patch with error_report(), as Yoshi mentioned?

Also, I would move the total_sectors calculation outside the loop -
though I have no idea how many iterations it typically has, so it might
not improve things a lot.

Kevin