2015-08-19 05:18:21

by Trond Myklebust

Subject: [PATCH] Revert "NFSv4: Remove incorrect check in can_open_delegated()"

This reverts commit 4e379d36c050b0117b5d10048be63a44f5036115.

This commit opens up a race between the recovery code and the open code.

Reported-by: Olga Kornievskaia <[email protected]>
Cc: [email protected] # v4.0+
Signed-off-by: Trond Myklebust <[email protected]>
---
fs/nfs/nfs4proc.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 9e9f7816cf24..95c5e8d39bef 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1156,6 +1156,8 @@ static int can_open_delegated(struct nfs_delegation *delegation, fmode_t fmode)
return 0;
if ((delegation->type & fmode) != fmode)
return 0;
+ if (test_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags))
+ return 0;
if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
return 0;
nfs_mark_delegation_referenced(delegation);
--
2.4.3

2015-08-19 13:01:22

by Olga Kornievskaia

Subject: Re: [PATCH] Revert "NFSv4: Remove incorrect check in can_open_delegated()"

Alternatively, I think the following would fix the problem too. If
this open for CLAIM_PREVIOUS, we don't need to check if it can be open
delegated.

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 3acb1eb..b53cb10 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1866,7 +1866,8 @@ static void nfs4_open_prepare(struct rpc_task *task, void
goto out_no_action;
rcu_read_lock();
delegation = rcu_dereference(NFS_I(data->state->inode)->delegati
- if (data->o_arg.claim != NFS4_OPEN_CLAIM_DELEGATE_CUR &&
+ if (data->o_arg.claim != NFS4_OPEN_CLAIM_PREVIOUS &&
+ data->o_arg.claim != NFS4_OPEN_CLAIM_DELEGATE_CUR &&
data->o_arg.claim != NFS4_OPEN_CLAIM_DELEG_CUR_FH &&
can_open_delegated(delegation, data->o_arg.fmode))
goto unlock_no_action;

On Wed, Aug 19, 2015 at 1:18 AM, Trond Myklebust
<[email protected]> wrote:
> This reverts commit 4e379d36c050b0117b5d10048be63a44f5036115.
>
> This commit opens up a race between the recovery code and the open code.
>
> Reported-by: Olga Kornievskaia <[email protected]>
> Cc: [email protected] # v4.0+
> Signed-off-by: Trond Myklebust <[email protected]>
> ---
> fs/nfs/nfs4proc.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 9e9f7816cf24..95c5e8d39bef 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -1156,6 +1156,8 @@ static int can_open_delegated(struct nfs_delegation *delegation, fmode_t fmode)
> return 0;
> if ((delegation->type & fmode) != fmode)
> return 0;
> + if (test_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags))
> + return 0;
> if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
> return 0;
> nfs_mark_delegation_referenced(delegation);
> --
> 2.4.3
>