On 3/15/22 10:39 AM, Chuck Lever III wrote:
On Mar 15, 2022, at 12:26 PM, Dai Ngo <dai.ngo@xxxxxxxxxx> wrote:
On 3/15/22 8:02 AM, J. Bruce Fields wrote:
On Fri, Mar 11, 2022 at 06:13:27PM -0800, Dai Ngo wrote:
Add callout function nfsd4_lm_lock_expired for lm_lock_expired.
If lock request has conflict with courtesy client then expire the
courtesy client and return no conflict to caller.
Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
---
fs/nfsd/nfs4state.c | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index a65d59510681..583ac807e98d 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -6578,10 +6578,47 @@ nfsd4_lm_notify(struct file_lock *fl)
}
}
+/**
+ * nfsd4_lm_lock_expired - check if lock conflict can be resolved.
+ *
+ * @fl: pointer to file_lock with a potential conflict
+ * Return values:
+ * %false: real conflict, lock conflict can not be resolved.
+ * %true: no conflict, lock conflict was resolved.
+ *
+ * Note that this function is called while the flc_lock is held.
+ */
+static bool
+nfsd4_lm_lock_expired(struct file_lock *fl)
+{
+ struct nfs4_lockowner *lo;
+ struct nfs4_client *clp;
+ bool rc = false;
+
+ if (!fl)
+ return false;
+ lo = (struct nfs4_lockowner *)fl->fl_owner;
+ clp = lo->lo_owner.so_client;
+
+ /* need to sync with courtesy client trying to reconnect */
+ spin_lock(&clp->cl_cs_lock);
+ if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
+ rc = true;
+ else {
+ if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
+ set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
+ rc = true;
+ }
+ }
I'd prefer:
if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags))
set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
we also need to set rc to true here.
if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
rc = true;
With v16 we need to check for NFSD4_CLIENT_EXPIRED first then
NFSD4_CLIENT_COURTESY because both flags can be set. In the
next patch version, we will clear NFSD4_CLIENT_COURTESY when
setting NFSD4_CLIENT_EXPIRED so the order of check does not
matter.
Same result, but more compact and straightforward, I think.
Chuck wants to replace the bits used for courtesy client in
cl_flags with a separate u8 field so it does not have to use
bit operation to set/test.
Code audit suggested there are really only four unique
combinations of the bit flags that are used.
Plus, taking a spin_lock and using bitops seems like overkill.
The rules for transitioning between the courtesy states are
straightforward, but need to be done in a critical section.
So I suggested storing the courtesy state in a lock-protected
unsigned int instead of using bit flags.
I will try what Chuck suggested.
If we hate it, we can go back to bit flags.
ok.
-Dai
+ spin_unlock(&clp->cl_cs_lock);
+ return rc;
+}
+
static const struct lock_manager_operations nfsd_posix_mng_ops = {
.lm_notify = nfsd4_lm_notify,
.lm_get_owner = nfsd4_lm_get_owner,
.lm_put_owner = nfsd4_lm_put_owner,
+ .lm_lock_expired = nfsd4_lm_lock_expired,
};
static inline void
--
2.9.5
--
Chuck Lever
