[PATCH v2 1/1] NFS: remove revoked delegation from server's delegation list

[PATCH v2 1/1] NFS: remove revoked delegation from server's delegation list

[Dai Ngo]

After the delegation is returned to the NFS server remove it
from the server's delegations list to reduce the time it takes
to scan this list.

Network trace captured while running the below script shows the
time taken to service the CB_RECALL increases gradually due to
the overhead of traversing the delegation list in
nfs_delegation_find_inode_server.

The NFS server in this test is a Solaris server which issues
CB_RECALL when receiving the all-zero stateid in the SETATTR.

mount=/mnt/data
for i in $(seq 1 20)
do
   echo $i
   mkdir $mount/testtarfile$i
   time  tar -C $mount/testtarfile$i -xf 5000_files.tar
done

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfs/delegation.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 20cb2008f9e4..035ba52742a5 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -1001,6 +1001,11 @@ void nfs_delegation_mark_returned(struct inode *inode,
 	}
 
 	nfs_mark_delegation_revoked(delegation);
+	clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
+	spin_unlock(&delegation->lock);
+	if (nfs_detach_delegation(NFS_I(inode), delegation, NFS_SERVER(inode)))
+		nfs_put_delegation(delegation);
+	goto out_rcu_unlock;
 
 out_clear_returning:
 	clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
-- 
2.43.0

Re: [PATCH v2 1/1] NFS: remove revoked delegation from server's delegation list

[Trond Myklebust]

On Tue, 2024-10-08 at 15:58 -0700, Dai Ngo wrote:
> After the delegation is returned to the NFS server remove it
> from the server's delegations list to reduce the time it takes
> to scan this list.
> 
> Network trace captured while running the below script shows the
> time taken to service the CB_RECALL increases gradually due to
> the overhead of traversing the delegation list in
> nfs_delegation_find_inode_server.
> 
> The NFS server in this test is a Solaris server which issues
> CB_RECALL when receiving the all-zero stateid in the SETATTR.
> 
> mount=/mnt/data
> for i in $(seq 1 20)
> do
>    echo $i
>    mkdir $mount/testtarfile$i
>    time  tar -C $mount/testtarfile$i -xf 5000_files.tar
> done
> 
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> ---
>  fs/nfs/delegation.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
> index 20cb2008f9e4..035ba52742a5 100644
> --- a/fs/nfs/delegation.c
> +++ b/fs/nfs/delegation.c
> @@ -1001,6 +1001,11 @@ void nfs_delegation_mark_returned(struct inode
> *inode,
>  	}
>  
>  	nfs_mark_delegation_revoked(delegation);
> +	clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
> +	spin_unlock(&delegation->lock);
> +	if (nfs_detach_delegation(NFS_I(inode), delegation,
> NFS_SERVER(inode)))
> +		nfs_put_delegation(delegation);
> +	goto out_rcu_unlock;
>  
>  out_clear_returning:
>  	clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);

OK, I can fix up nfs_revoke_delegation() later. Thanks!

Reviewed-by: Trond Myklebust <trond.myklebust@hammerspace.com>

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com