The TEST_STATEID and FREE_STATEID operations can return
-NFS4ERR_BAD_STATEID, -NFS4ERR_OLD_STATEID, or -NFS4ERR_DEADSESSION.
nfs41_{test,free}_stateid() should not pass these errors to
nfs4_handle_exception() during state recovery, since that will
recursively kick off state recovery again, resulting in a deadlock.
In particular, when the TEST_STATEID operation returns NFS4_OK,
res.status can contain one of these errors. _nfs41_test_stateid()
replaces NFS4_OK with the value in res.status, which is then returned
to callers.
But res.status is not passed through nfs4_stat_to_errno(), and thus is
a positive NFS4ERR value. Currently callers are only interested in
!NFS4_OK, and nfs4_handle_exception() ignores positive values.
Thus the res.status values are currently ignored by
nfs4_handle_exception() and won't cause the deadlock above. Thanks to
this missing negative, it is only when these operations fail (which
is very rare) that a deadlock can occur.
Bryan agrees the original intent was to return res.status as a
negative NFS4ERR value to callers of nfs41_test_stateid().
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
fs/nfs/nfs4proc.c | 24 +++++++++++++-----------
1 files changed, 13 insertions(+), 11 deletions(-)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 15fc7e4..9a0397c 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6589,10 +6589,9 @@ static int _nfs41_test_stateid(struct nfs_server *server, nfs4_stateid *stateid)
nfs41_init_sequence(&args.seq_args, &res.seq_res, 0);
status = nfs4_call_sync_sequence(server->client, server, &msg, &args.seq_args, &res.seq_res, 1);
-
- if (status == NFS_OK)
- return res.status;
- return status;
+ if (status != NFS_OK)
+ return status;
+ return -res.status;
}
static int nfs41_test_stateid(struct nfs_server *server, nfs4_stateid *stateid)
@@ -6600,9 +6599,10 @@ static int nfs41_test_stateid(struct nfs_server *server, nfs4_stateid *stateid)
struct nfs4_exception exception = { };
int err;
do {
- err = nfs4_handle_exception(server,
- _nfs41_test_stateid(server, stateid),
- &exception);
+ err = _nfs41_test_stateid(server, stateid);
+ if (err != -NFS4ERR_DELAY)
+ break;
+ nfs4_handle_exception(server, err, &exception);
} while (exception.retry);
return err;
}
@@ -6620,7 +6620,8 @@ static int _nfs4_free_stateid(struct nfs_server *server, nfs4_stateid *stateid)
};
nfs41_init_sequence(&args.seq_args, &res.seq_res, 0);
- return nfs4_call_sync_sequence(server->client, server, &msg, &args.seq_args, &res.seq_res, 1);
+ return nfs4_call_sync_sequence(server->client, server, &msg,
+ &args.seq_args, &res.seq_res, 1);
}
static int nfs41_free_stateid(struct nfs_server *server, nfs4_stateid *stateid)
@@ -6628,9 +6629,10 @@ static int nfs41_free_stateid(struct nfs_server *server, nfs4_stateid *stateid)
struct nfs4_exception exception = { };
int err;
do {
- err = nfs4_handle_exception(server,
- _nfs4_free_stateid(server, stateid),
- &exception);
+ err = _nfs4_free_stateid(server, stateid);
+ if (err != -NFS4ERR_DELAY)
+ break;
+ nfs4_handle_exception(server, err, &exception);
} while (exception.retry);
return err;
}
--
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