Re: [RFC] [PATCHv3 1/9] reiser4: block_alloc: add BA_SOME_SPACE flag for grabbing a fixed amount of space.

[Edward Shishkin <edward.shishkin@gmail.com>]

On 08/17/2014 11:52 PM, Ivan Shapovalov wrote:
> This is used for FITRIM ioctl which will iteratively grab, allocate and trim disk space
> bit by bit to avoid starving the rest of system.
>
> Signed-off-by: Ivan Shapovalov <intelfx100@gmail.com>
> ---
>   fs/reiser4/block_alloc.c | 5 +++++
>   fs/reiser4/block_alloc.h | 5 ++++-
>   2 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/fs/reiser4/block_alloc.c b/fs/reiser4/block_alloc.c
> index d3d730c..9eed7fc 100644
> --- a/fs/reiser4/block_alloc.c
> +++ b/fs/reiser4/block_alloc.c
> @@ -276,6 +276,11 @@ reiser4_grab(reiser4_context * ctx, __u64 count, reiser4_ba_flags_t flags)
>   
>   	free_blocks = sbinfo->blocks_free;
>   
> +	if (flags & BA_SOME_SPACE) {
> +		/* Reserve 25% of all free space. */

if (free_blocks == 0) {
         /* nothing to trim */
         ret= RETERR(-ENOSPC);
         goto unlock_and_ret;
}

> +		count = free_blocks >> 2;

if (count == 0)
         /* there are 1, 2, or 3 free blocks  */
         count = free_blocks;

> +	}
> +
>   	if ((use_reserved && free_blocks < count) ||
>   	    (!use_reserved && free_blocks < count + sbinfo->blocks_reserved)) {
>   		ret = RETERR(-ENOSPC);
> diff --git a/fs/reiser4/block_alloc.h b/fs/reiser4/block_alloc.h
> index a4e98af..bfc6be9 100644
> --- a/fs/reiser4/block_alloc.h
> +++ b/fs/reiser4/block_alloc.h
> @@ -79,7 +79,10 @@ enum reiser4_ba_flags {
>   	BA_FORCE = (1 << 5),
>   
>   	/* use default start value for free blocks search. */
> -	BA_USE_DEFAULT_SEARCH_START = (1 << 6)
> +	BA_USE_DEFAULT_SEARCH_START = (1 << 6),
> +
> +	/* reserve some fixed amount of space */
> +	BA_SOME_SPACE = (1 << 7),
>   };
>   
>   typedef enum reiser4_ba_flags reiser4_ba_flags_t;