Re: [Qemu-devel] [PATCH 08/20] nfs: Handle failure for potentially large allocations

[ronnie sahlberg]

For this case and for the iscsi case, isn't it likely that once this
happens the guest is pretty much doomed since I/O to the disk will no
longer work ?

Should we also change the block layer so that IF *_readv/_writev fails
with -ENOMEM
then it should try again but break the request up into a chain of
smaller chunks ?



On Wed, May 21, 2014 at 9:28 AM, Kevin Wolf <address@hidden> wrote:
> Some code in the block layer makes potentially huge allocations. Failure
> is not completely unexpected there, so avoid aborting qemu and handle
> out-of-memory situations gracefully.
>
> This patch addresses the allocations in the nfs block driver.
>
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
>  block/nfs.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/block/nfs.c b/block/nfs.c
> index 539bd95..e3d6216 100644
> --- a/block/nfs.c
> +++ b/block/nfs.c
> @@ -165,7 +165,11 @@ static int coroutine_fn nfs_co_writev(BlockDriverState 
> *bs,
>
>      nfs_co_init_task(client, &task);
>
> -    buf = g_malloc(nb_sectors * BDRV_SECTOR_SIZE);
> +    buf = g_try_malloc(nb_sectors * BDRV_SECTOR_SIZE);
> +    if (buf == NULL) {
> +        return -ENOMEM;
> +    }
> +
>      qemu_iovec_to_buf(iov, 0, buf, nb_sectors * BDRV_SECTOR_SIZE);
>
>      if (nfs_pwrite_async(client->context, client->fh,
> --
> 1.8.3.1
>
>