git: 431a136f423b - stable/13 - nfsv4 client: fix forced dismount when sleeping in the renew thread

[Rick Macklem]

The branch stable/13 has been updated by rmacklem:

URL: https://cgit.FreeBSD.org/src/commit/?id=431a136f423b7487fab33ea8d431af4f67b7e226

commit 431a136f423b7487fab33ea8d431af4f67b7e226
Author:     Rick Macklem <rmacklem at FreeBSD.org>
AuthorDate: 2021-03-23 20:04:37 +0000
Commit:     Rick Macklem <rmacklem at FreeBSD.org>
CommitDate: 2021-04-11 22:23:23 +0000

    nfsv4 client: fix forced dismount when sleeping in the renew thread
    
    During a recent NFSv4 testing event a test server caused a hang
    where "umount -N" failed.  The renew thread was sleeping on "nfsv4lck"
    and the "umount" was sleeping, waiting for the renew thread to
    terminate.
    
    This is the second of two patches that is hoped to fix the renew thread
    so that it will terminate when "umount -N" is done on the mount.
    
    This patch adds a 5second timeout on the msleep()s and checks for
    the forced dismount flag so that the renew thread will
    wake up and see the forced dismount flag.  Normally a wakeup()
    will occur in less than 5seconds, but if a premature return from
    msleep() does occur, it will simply loop around and msleep() again.
    The patch also adds the "mp" argument to nfsv4_lock() so that it
    will return when the forced dismount flag is set.
    
    While here, replace the nfsmsleep() wrapper that was used for portability
    with the actual msleep() call.
    
    (cherry picked from commit 82ee386c2afb42388804c1189751b83048953433)
---
 sys/fs/nfsclient/nfs_clstate.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/sys/fs/nfsclient/nfs_clstate.c b/sys/fs/nfsclient/nfs_clstate.c
index 227d82a5f7f3..4e3abf82c96a 100644
--- a/sys/fs/nfsclient/nfs_clstate.c
+++ b/sys/fs/nfsclient/nfs_clstate.c
@@ -2550,10 +2550,12 @@ nfscl_renewthread(struct nfsclclient *clp, NFSPROC_T *p)
 	struct nfsclrecalllayout *recallp;
 	struct nfsclds *dsp;
 	bool retok;
+	struct mount *mp;
 
 	cred = newnfs_getcred();
 	NFSLOCKCLSTATE();
 	clp->nfsc_flags |= NFSCLFLAGS_HASTHREAD;
+	mp = clp->nfsc_nmp->nm_mountp;
 	NFSUNLOCKCLSTATE();
 	for(;;) {
 		newnfs_setroot(cred);
@@ -2652,14 +2654,18 @@ tryagain:
 				    }
 				    dp->nfsdl_rwlock.nfslock_lock |=
 					NFSV4LOCK_WANTED;
-				    (void) nfsmsleep(&dp->nfsdl_rwlock,
-					NFSCLSTATEMUTEXPTR, PZERO, "nfscld",
-					NULL);
+				    msleep(&dp->nfsdl_rwlock,
+					NFSCLSTATEMUTEXPTR, PVFS, "nfscld",
+					5 * hz);
+				    if (NFSCL_FORCEDISM(mp))
+					goto terminate;
 				    goto tryagain;
 				}
 				while (!igotlock) {
 				    igotlock = nfsv4_lock(&clp->nfsc_lock, 1,
-					&islept, NFSCLSTATEMUTEXPTR, NULL);
+					&islept, NFSCLSTATEMUTEXPTR, mp);
+				    if (igotlock == 0 && NFSCL_FORCEDISM(mp))
+					goto terminate;
 				    if (islept)
 					goto tryagain;
 				}
@@ -2739,9 +2745,11 @@ tryagain2:
 				     NFSV4LOCK_LOCK) != 0) {
 					lyp->nfsly_lock.nfslock_lock |=
 					    NFSV4LOCK_WANTED;
-					nfsmsleep(&lyp->nfsly_lock.nfslock_lock,
-					    NFSCLSTATEMUTEXPTR, PZERO, "nfslyp",
-					    NULL);
+					msleep(&lyp->nfsly_lock.nfslock_lock,
+					    NFSCLSTATEMUTEXPTR, PVFS, "nfslyp",
+					    5 * hz);
+					if (NFSCL_FORCEDISM(mp))
+					    goto terminate;
 					goto tryagain2;
 				}
 				/* Move the layout to the recall list. */
@@ -2850,6 +2858,7 @@ tryagain2:
 		if ((clp->nfsc_flags & NFSCLFLAGS_RECOVER) == 0)
 			(void)mtx_sleep(clp, NFSCLSTATEMUTEXPTR, PWAIT, "nfscl",
 			    hz);
+terminate:
 		if (clp->nfsc_flags & NFSCLFLAGS_UMOUNT) {
 			clp->nfsc_flags &= ~NFSCLFLAGS_HASTHREAD;
 			NFSUNLOCKCLSTATE();