git: 1f64f93a0921 - stable/13 - nfscl: Add a check for "has acquired a delegation" to nfscl_removedeleg()

The branch stable/13 has been updated by rmacklem:

URL: https://cgit.FreeBSD.org/src/commit/?id=1f64f93a0921fad407dd4cfbbea06a831288cf78

commit 1f64f93a0921fad407dd4cfbbea06a831288cf78
Author:     Rick Macklem <rmacklem@FreeBSD.org>
AuthorDate: 2021-09-27 01:37:25 +0000
Commit:     Rick Macklem <rmacklem@FreeBSD.org>
CommitDate: 2021-10-19 23:19:40 +0000

    nfscl: Add a check for "has acquired a delegation" to nfscl_removedeleg()
    
    Commit 5e5ca4c8fc53 added a flag to a NFSv4 mount point that is set when
    the first delegation is acquired from the NFSv4 server.
    
    For a common case where delegations are not being issued by the
    NFSv4 server, the nfscl_removedeleg() code acquires the mutex lock for
    open/lock state, finds the delegation list empty, then just unlocks the
    mutex and returns. This patch adds a check of the flag to avoid the
    need to acquire the mutex for this common case.
    
    This change appears to be performance neutral for a small number
    of opens, but should reduce lock contention for a large number of opens
    for the common case where server is not issuing delegations.
    
    This commit should not affect the high level semantics of delegation
    handling.
    
    (cherry picked from commit 62c5be4ab4c8b8127185286e148638cb8cdf45f4)
---
 sys/fs/nfsclient/nfs_clstate.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/sys/fs/nfsclient/nfs_clstate.c b/sys/fs/nfsclient/nfs_clstate.c
index bb2c78a72ed9..8d1c4de0ba8e 100644
--- a/sys/fs/nfsclient/nfs_clstate.c
+++ b/sys/fs/nfsclient/nfs_clstate.c
@@ -4606,6 +4606,12 @@ nfscl_removedeleg(vnode_t vp, NFSPROC_T *p, nfsv4stateid_t *stp)
 	int igotlock = 0, triedrecall = 0, needsrecall, retcnt = 0, islept;
 
 	nmp = VFSTONFS(vp->v_mount);
+	NFSLOCKMNT(nmp);
+	if ((nmp->nm_privflag & NFSMNTP_DELEGISSUED) == 0) {
+		NFSUNLOCKMNT(nmp);
+		return (retcnt);
+	}
+	NFSUNLOCKMNT(nmp);
 	np = VTONFS(vp);
 	NFSLOCKCLSTATE();
 	/*