Re: [PATCH 5/5] rumpdisk: Fault-in the memory pages

[Samuel Thibault]

Damien Zammit, le dim. 26 déc. 2021 22:38:57 +1100, a ecrit:
> This ensures memory pages are allocated before written to.

Applied, thanks!

> ---
>  rumpdisk/block-rump.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/rumpdisk/block-rump.c b/rumpdisk/block-rump.c
> index 7a4a167e..fe97bf85 100644
> --- a/rumpdisk/block-rump.c
> +++ b/rumpdisk/block-rump.c
> @@ -284,10 +284,18 @@ rumpdisk_device_write (void *d, mach_port_t reply_port,
>  {
>    struct block_data *bd = d;
>    ssize_t written;
> +  volatile uint8_t dummy_read;
> +  int pagesize = sysconf (_SC_PAGE_SIZE);
> +  int npages = (count + pagesize - 1) / pagesize;
> +  int i;
>  
>    if ((bd->mode & D_WRITE) == 0)
>      return D_INVALID_OPERATION;
>  
> +  /* Fault-in the memory pages by reading a single byte of each */
> +  for (i = 0; i < npages; i++)
> +    dummy_read = ((volatile uint8_t *)data)[i * pagesize];
> +
>    written = rump_sys_pwrite (bd->rump_fd, (const void *)data, (size_t)count, 
> (off_t)bn * bd->block_size);
>    vm_deallocate (mach_task_self (), (vm_address_t) data, count);
>  
> @@ -313,6 +321,7 @@ rumpdisk_device_read (void *d, mach_port_t reply_port,
>    vm_address_t buf;
>    int pagesize = sysconf (_SC_PAGE_SIZE);
>    int npages = (count + pagesize - 1) / pagesize;
> +  int i;
>    ssize_t err;
>    kern_return_t ret;
>  
> @@ -327,8 +336,9 @@ rumpdisk_device_read (void *d, mach_port_t reply_port,
>    if (ret != KERN_SUCCESS)
>      return ENOMEM;
>  
> -  /* Ensure physical allocation.  */
> -  memset (buf, 0, npages * pagesize);
> +  /* Ensure physical allocation by writing a single byte of each */
> +  for (i = 0; i < npages; i++)
> +    ((uint8_t *)buf)[i * pagesize] = 0;
>  
>    err = rump_sys_pread (bd->rump_fd, (void *)buf, (size_t)count, (off_t)bn * 
> bd->block_size);
>    if (err < 0)
> -- 
> 2.33.1
> 
> 

-- 
Samuel
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