[sheepdog] [PATCH 1/2] sheep/recovery: get recovering local object right

[Hitoshi Mitake]

At Mon,  2 Mar 2015 16:02:37 +0800,
Liu Yuan wrote:
> 
> From: Liu Yuan <liuyuan at cmss.chinamobile.com>
> 
> One of the acceleration for recovery is we try to recover the object from local
> node as much as possible. It is straightforward implemented:
> 
> 1 firstly get the hash of the object to be recoveried from stale directry if any
> 2 then compare the fingerprint to the remote node
> 3 if identical, then we can safely recover it from local stale directory.
> 
> But this logic is never executed in the following case:
> 
> 0 sheep try to recover object A at from epoch 5, we note it as A.5
> 1 but sheep find we have a local copy A.2 due to a multiple node events
> 2 then sheep get the fingerprint of A.2 and then compare to remote node.
> 3 the figerprints are identical, so this sheep tries to recover it from A.2
> 4 if, unfortunately, A.5 is as well calcuated onto this node, even though this
>   sheep dosen't have it, our code will first try to link A.5
> 5 unfortunately, A.5 is never out there and before we really try to link A.2,
>   sheep fail out because ->link(A.5) return error.
> 
> The fix is easy, just try to ->link(A.2) before ->link(A.5).
> 
> Signed-off-by: Liu Yuan <liuyuan at cmss.chinamobile.com>
> ---
>  sheep/recovery.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)

Applied this series, thanks.
Hitoshi

> 
> diff --git a/sheep/recovery.c b/sheep/recovery.c
> index 8d94d4f..36ef8a0 100644
> --- a/sheep/recovery.c
> +++ b/sheep/recovery.c
> @@ -265,13 +265,6 @@ static int recover_object_from(struct recovery_obj_work *row,
>  	struct sd_rsp *rsp = (struct sd_rsp *)&hdr;
>  	struct siocb iocb = { 0 };
>  
> -	if (node_is_local(node)) {
> -		if (tgt_epoch < sys_epoch())
> -			return sd_store->link(oid, tgt_epoch);
> -
> -		return SD_RES_NO_OBJ;
> -	}
> -
>  	/* compare sha1 hash value first */
>  	if (local_epoch > 0) {
>  		sd_init_req(&hdr, SD_OP_GET_HASH);
> @@ -290,6 +283,13 @@ static int recover_object_from(struct recovery_obj_work *row,
>  		}
>  	}
>  
> +	if (node_is_local(node)) {
> +		if (tgt_epoch < sys_epoch())
> +			return sd_store->link(oid, tgt_epoch);
> +
> +		return SD_RES_NO_OBJ;
> +	}
> +
>  	rlen = get_store_objsize(oid);
>  	buf = xvalloc(rlen);
>  
> -- 
> 1.9.1
> 
> -- 
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