The delegation code mostly pretends to support either read or write
delegations. However, correct support for write delegations would
require, for example, breaking of delegations (and/or implementation of
cb_getattr) on stat. Currently all that stops us from handing out
delegations is a subtle reference-counting issue.
Avoid confusion by adding an earlier check that explicitly refuses write
delegations.
For now, though, I'm not going so far as to rip out existing
half-support for write delegations, in case we get around to using that
soon.
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
---
fs/nfsd/nfs4state.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 9cc3b78..c07c988 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -170,6 +170,13 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_stateid *stp, struct svc_f
struct nfs4_cb_conn *cb = &stp->st_stateowner->so_client->cl_cb_conn;
dprintk("NFSD alloc_init_deleg\n");
+ /*
+ * Major work on the lease subsystem (for example, to support
+ * calbacks on stat) will be required before we can support
+ * write delegations properly.
+ */
+ if (type != NFS4_OPEN_DELEGATE_READ)
+ return NULL;
if (fp->fi_had_conflict)
return NULL;
if (num_delegations > max_delegations)
--
1.7.0.4
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