The NFSv4.1 protocol adds support for directory delegations, but it
specifies that if you already have a delegation and try to request a new
one on the same filehandle, the server must reply that the delegation is
unavailable.
Add a new lease manager callback to allow the lease manager (nfsd in
this case) to impose this extra check when performing a setlease.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/locks.c | 5 +++++
include/linux/filelock.h | 14 ++++++++++++++
2 files changed, 19 insertions(+)
diff --git a/fs/locks.c b/fs/locks.c
index a35d033dcaf0b604b73395260562af08f7711c12..1985f38d326d938f58009e0880b45e588af6a422 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1826,6 +1826,11 @@ generic_add_lease(struct file *filp, int arg, struct file_lease **flp, void **pr
continue;
}
+ /* Allow the lease manager to veto the setlease */
+ if (lease->fl_lmops->lm_may_setlease &&
+ !lease->fl_lmops->lm_may_setlease(lease, fl))
+ goto out;
+
/*
* No exclusive leases if someone else has a lease on
* this file:
diff --git a/include/linux/filelock.h b/include/linux/filelock.h
index c412ded9171ed781ebe9e8d2e0426dcd10793292..60c76c8fb4dfdcaaa2cfa3f41f0f26ffcb3db29f 100644
--- a/include/linux/filelock.h
+++ b/include/linux/filelock.h
@@ -49,6 +49,20 @@ struct lease_manager_operations {
int (*lm_change)(struct file_lease *, int, struct list_head *);
void (*lm_setup)(struct file_lease *, void **);
bool (*lm_breaker_owns_lease)(struct file_lease *);
+
+ /**
+ * lm_may_setlease - extra conditions for setlease
+ * @new: new file_lease being set
+ * @old: old (extant) file_lease
+ *
+ * This allows the lease manager to add extra conditions when
+ * setting a lease, based on the presence of an existing lease.
+ *
+ * Return values:
+ * %false: @new and @old conflict
+ * %true: No conflict detected
+ */
+ bool (*lm_may_setlease)(struct file_lease *new, struct file_lease *old);
};
struct lock_manager {
--
2.49.0
