git: 2bc16e8aaf75 - main - VFS: remove MNTK_MARKER

[Jason A. Harmening]

The branch main has been updated by jah:

URL: https://cgit.FreeBSD.org/src/commit/?id=2bc16e8aaf7577e702ce1dbcb343f11c53e8dce0

commit 2bc16e8aaf7577e702ce1dbcb343f11c53e8dce0
Author:     Jason A. Harmening <jah at FreeBSD.org>
AuthorDate: 2021-07-18 04:26:48 +0000
Commit:     Jason A. Harmening <jah at FreeBSD.org>
CommitDate: 2021-07-24 19:52:32 +0000

    VFS: remove MNTK_MARKER
    
    We no longer allow upper filesystems to be unregistered from the base
    mount while vfs_notify_upper() or any other upper operation is pending.
    New upper mounts can still be registered during this period, but they
    will be added at the end of the upper mount tailq.  We therefore no
    longer need to allocate marker nodes during vfs_notify_upper() to keep
    our place in the iteration.
    
    Reviewed by:    kib, mckusick
    Tested by:      pho
    Differential Revision:  https://reviews.freebsd.org/D31016
---
 sys/kern/vfs_subr.c | 34 ++--------------------------------
 sys/sys/mount.h     |  1 -
 2 files changed, 2 insertions(+), 33 deletions(-)

diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 8add6951645f..23f6ec9cf3fd 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -3891,52 +3891,26 @@ vgone(struct vnode *vp)
 	VI_UNLOCK(vp);
 }
 
-static void
-notify_lowervp_vfs_dummy(struct mount *mp __unused,
-    struct vnode *lowervp __unused)
-{
-}
-
-struct notify_mount {
-	struct mount mp;
-	struct mount_upper_node upper;
-};
-
 /*
  * Notify upper mounts about reclaimed or unlinked vnode.
  */
 void
 vfs_notify_upper(struct vnode *vp, int event)
 {
-	static struct vfsops vgonel_vfsops = {
-		.vfs_reclaim_lowervp = notify_lowervp_vfs_dummy,
-		.vfs_unlink_lowervp = notify_lowervp_vfs_dummy,
-	};
 	struct mount *mp;
 	struct mount_upper_node *ump;
-	struct notify_mount *mmp;
 
-	mp = vp->v_mount;
+	mp = atomic_load_ptr(&vp->v_mount);
 	if (mp == NULL)
 		return;
 	if (TAILQ_EMPTY(&mp->mnt_notify))
 		return;
 
-	mmp = malloc(sizeof(*mmp), M_TEMP, M_WAITOK | M_ZERO);
-	mmp->mp.mnt_op = &vgonel_vfsops;
-	mmp->mp.mnt_kern_flag |= MNTK_MARKER;
-	mmp->upper.mp = &mmp->mp;
 	MNT_ILOCK(mp);
 	mp->mnt_upper_pending++;
 	KASSERT(mp->mnt_upper_pending > 0,
 	    ("%s: mnt_upper_pending %d", __func__, mp->mnt_upper_pending));
-	for (ump = TAILQ_FIRST(&mp->mnt_notify); ump != NULL;) {
-		if ((ump->mp->mnt_kern_flag & MNTK_MARKER) != 0) {
-			ump = TAILQ_NEXT(ump, mnt_upper_link);
-			continue;
-		}
-		TAILQ_INSERT_AFTER(&mp->mnt_notify, ump, &mmp->upper,
-		    mnt_upper_link);
+	TAILQ_FOREACH(ump, &mp->mnt_notify, mnt_upper_link) {
 		MNT_IUNLOCK(mp);
 		switch (event) {
 		case VFS_NOTIFY_UPPER_RECLAIM:
@@ -3950,10 +3924,7 @@ vfs_notify_upper(struct vnode *vp, int event)
 			break;
 		}
 		MNT_ILOCK(mp);
-		ump = TAILQ_NEXT(&mmp->upper, mnt_upper_link);
-		TAILQ_REMOVE(&mp->mnt_notify, &mmp->upper, mnt_upper_link);
 	}
-	free(mmp, M_TEMP);
 	mp->mnt_upper_pending--;
 	if ((mp->mnt_kern_flag & MNTK_UPPER_WAITER) != 0 &&
 	    mp->mnt_upper_pending == 0) {
@@ -4391,7 +4362,6 @@ DB_SHOW_COMMAND(mount, db_show_mount)
 	MNT_KERN_FLAG(MNTK_RECURSE);
 	MNT_KERN_FLAG(MNTK_UPPER_WAITER);
 	MNT_KERN_FLAG(MNTK_LOOKUP_EXCL_DOTDOT);
-	MNT_KERN_FLAG(MNTK_MARKER);
 	MNT_KERN_FLAG(MNTK_USES_BCACHE);
 	MNT_KERN_FLAG(MNTK_FPLOOKUP);
 	MNT_KERN_FLAG(MNTK_TASKQUEUE_WAITER);
diff --git a/sys/sys/mount.h b/sys/sys/mount.h
index 2082ff089d69..016c7e9c188d 100644
--- a/sys/sys/mount.h
+++ b/sys/sys/mount.h
@@ -488,7 +488,6 @@ struct mntoptnames {
 #define	MNTK_RECURSE		0x00000200 /* pending recursive unmount */
 #define	MNTK_UPPER_WAITER	0x00000400 /* waiting to drain MNTK_UPPER_PENDING */
 #define	MNTK_LOOKUP_EXCL_DOTDOT	0x00000800
-#define	MNTK_MARKER		0x00001000
 #define	MNTK_UNMAPPED_BUFS	0x00002000
 #define	MNTK_USES_BCACHE	0x00004000 /* FS uses the buffer cache. */
 #define	MNTK_TEXT_REFS		0x00008000 /* Keep use ref for text */