Add mnt_noasync counter to better handle interleaved calls to nmount(),

sync() and sync_fsync() without losing MNT_ASYNC.  Add MNTK_ASYNC flag
which is set only when MNT_ASYNC is set and mnt_noasync is zero, and
check that flag instead of MNT_ASYNC before initiating async io.

10 files changed, 40 insertions, 18 deletions

diff --git a/sys/boot/pc98/boot2/inode.h b/sys/boot/pc98/boot2/inode.h
index 9a59f99..add9bb9 100644
--- a/sys/boot/pc98/boot2/inode.h
+++ b/sys/boot/pc98/boot2/inode.h
@@ -147,7 +147,7 @@ struct indir {
 
 /* Determine if soft dependencies are being done */
 #define DOINGSOFTDEP(vp)	((vp)->v_mount->mnt_flag & MNT_SOFTDEP)
-#define DOINGASYNC(vp)		((vp)->v_mount->mnt_flag & MNT_ASYNC)
+#define DOINGASYNC(vp)		((vp)->v_mount->mnt_kern_flag & MNTK_ASYNC)
 
 /* This overlays the fid structure (see mount.h). */
 struct ufid {
diff --git a/sys/gnu/fs/ext2fs/ext2_inode.c b/sys/gnu/fs/ext2fs/ext2_inode.c
index 9f84fd4..04a9d46 100644
--- a/sys/gnu/fs/ext2fs/ext2_inode.c
+++ b/sys/gnu/fs/ext2fs/ext2_inode.c
@@ -92,7 +92,7 @@ ext2_update(vp, waitfor)
 	}
 	ext2_i2ei(ip, (struct ext2_inode *)((char *)bp->b_data +
 	    EXT2_INODE_SIZE * ino_to_fsbo(fs, ip->i_number)));
-	if (waitfor && (vp->v_mount->mnt_flag & MNT_ASYNC) == 0)
+	if (waitfor && (vp->v_mount->mnt_kern_flag & MNTK_ASYNC) == 0)
 		return (bwrite(bp));
 	else {
 		bdwrite(bp);
diff --git a/sys/kern/vfs_cluster.c b/sys/kern/vfs_cluster.c
index b749f56..4c2cfaf 100644
--- a/sys/kern/vfs_cluster.c
+++ b/sys/kern/vfs_cluster.c
@@ -595,7 +595,7 @@ cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount)
 	int async;
 
 	if (vp->v_type == VREG) {
-		async = vp->v_mount->mnt_flag & MNT_ASYNC;
+		async = vp->v_mount->mnt_kern_flag & MNTK_ASYNC;
 		lblocksize = vp->v_mount->mnt_stat.f_iosize;
 	} else {
 		async = 0;
diff --git a/sys/kern/vfs_extattr.c b/sys/kern/vfs_extattr.c
index 147b31e..d23f19b 100644
--- a/sys/kern/vfs_extattr.c
+++ b/sys/kern/vfs_extattr.c
@@ -122,7 +122,6 @@ sync(td, uap)
 {
 	struct mount *mp, *nmp;
 	int vfslocked;
-	int asyncflag;
 
 	mtx_lock(&mountlist_mtx);
 	for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp) {
@@ -134,13 +133,16 @@ sync(td, uap)
 		if ((mp->mnt_flag & MNT_RDONLY) == 0 &&
 		    vn_start_write(NULL, &mp, V_NOWAIT) == 0) {
 			MNT_ILOCK(mp);
-			asyncflag = mp->mnt_flag & MNT_ASYNC;
-			mp->mnt_flag &= ~MNT_ASYNC;
+			mp->mnt_noasync++;
+			mp->mnt_kern_flag &= ~MNTK_ASYNC;
 			MNT_IUNLOCK(mp);
 			vfs_msync(mp, MNT_NOWAIT);
 			VFS_SYNC(mp, MNT_NOWAIT, td);
 			MNT_ILOCK(mp);
-			mp->mnt_flag |= asyncflag;
+			mp->mnt_noasync--;
+			if ((mp->mnt_flag & MNT_ASYNC) != 0 &&
+			    mp->mnt_noasync == 0)
+				mp->mnt_kern_flag |= MNTK_ASYNC;
 			MNT_IUNLOCK(mp);
 			vn_finished_write(mp);
 		}
diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
index f99b083..db40943 100644
--- a/sys/kern/vfs_mount.c
+++ b/sys/kern/vfs_mount.c
@@ -946,6 +946,8 @@ vfs_domount(
 		mp->mnt_flag |= MNT_RDONLY;
 	mp->mnt_flag &=~ MNT_UPDATEMASK;
 	mp->mnt_flag |= fsflags & (MNT_UPDATEMASK | MNT_FORCE | MNT_ROOTFS);
+	if ((mp->mnt_flag & MNT_ASYNC) == 0)
+		mp->mnt_kern_flag &= ~MNTK_ASYNC;
 	MNT_IUNLOCK(mp);
 	/*
 	 * Mount the filesystem.
@@ -981,6 +983,10 @@ vfs_domount(
 		    ~(MNT_UPDATE | MNT_RELOAD | MNT_FORCE | MNT_SNAPSHOT);
 		if (error)
 			mp->mnt_flag = flag;
+		if ((mp->mnt_flag & MNT_ASYNC) != 0 && mp->mnt_noasync == 0)
+			mp->mnt_kern_flag |= MNTK_ASYNC;
+		else
+			mp->mnt_kern_flag &= ~MNTK_ASYNC;
 		MNT_IUNLOCK(mp);
 		if ((mp->mnt_flag & MNT_RDONLY) == 0) {
 			if (mp->mnt_syncer == NULL)
@@ -997,6 +1003,12 @@ vfs_domount(
 		vrele(vp);
 		return (error);
 	}
+	MNT_ILOCK(mp);
+	if ((mp->mnt_flag & MNT_ASYNC) != 0 && mp->mnt_noasync == 0)
+		mp->mnt_kern_flag |= MNTK_ASYNC;
+	else
+		mp->mnt_kern_flag &= ~MNTK_ASYNC;
+	MNT_IUNLOCK(mp);
 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 	/*
 	 * Put the new filesystem on the mount list after root.
@@ -1196,6 +1208,7 @@ dounmount(mp, flags, td)
 	MNT_ILOCK(mp);
 	async_flag = mp->mnt_flag & MNT_ASYNC;
 	mp->mnt_flag &= ~MNT_ASYNC;
+	mp->mnt_kern_flag &= ~MNTK_ASYNC;
 	MNT_IUNLOCK(mp);
 	cache_purgevfs(mp);	/* remove cache entries for this file sys */
 	if (mp->mnt_syncer != NULL)
@@ -1238,6 +1251,8 @@ dounmount(mp, flags, td)
 		MNT_ILOCK(mp);
 		mp->mnt_kern_flag &= ~(MNTK_UNMOUNT | MNTK_UNMOUNTF);
 		mp->mnt_flag |= async_flag;
+		if ((mp->mnt_flag & MNT_ASYNC) != 0 && mp->mnt_noasync == 0)
+			mp->mnt_kern_flag |= MNTK_ASYNC;
 		lockmgr(&mp->mnt_lock, LK_RELEASE, NULL, td);
 		if (mp->mnt_kern_flag & MNTK_MWAIT)
 			wakeup(mp);
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 72c4b5c..c5189ed 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -3051,7 +3051,7 @@ sync_fsync(struct vop_fsync_args *ap)
 	struct vnode *syncvp = ap->a_vp;
 	struct mount *mp = syncvp->v_mount;
 	struct thread *td = ap->a_td;
-	int error, asyncflag;
+	int error;
 	struct bufobj *bo;
 
 	/*
@@ -3082,14 +3082,15 @@ sync_fsync(struct vop_fsync_args *ap)
 		return (0);
 	}
 	MNT_ILOCK(mp);
-	asyncflag = mp->mnt_flag & MNT_ASYNC;
-	mp->mnt_flag &= ~MNT_ASYNC;
+	mp->mnt_noasync++;
+	mp->mnt_kern_flag &= ~MNTK_ASYNC;
 	MNT_IUNLOCK(mp);
 	vfs_msync(mp, MNT_NOWAIT);
 	error = VFS_SYNC(mp, MNT_LAZY, td);
 	MNT_ILOCK(mp);
-	if (asyncflag)
-		mp->mnt_flag |= MNT_ASYNC;
+	mp->mnt_noasync--;
+	if ((mp->mnt_flag & MNT_ASYNC) != 0 && mp->mnt_noasync == 0)
+		mp->mnt_kern_flag |= MNTK_ASYNC;
 	MNT_IUNLOCK(mp);
 	vn_finished_write(mp);
 	vfs_unbusy(mp, td);
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index 147b31e..d23f19b 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -122,7 +122,6 @@ sync(td, uap)
 {
 	struct mount *mp, *nmp;
 	int vfslocked;
-	int asyncflag;
 
 	mtx_lock(&mountlist_mtx);
 	for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp) {
@@ -134,13 +133,16 @@ sync(td, uap)
 		if ((mp->mnt_flag & MNT_RDONLY) == 0 &&
 		    vn_start_write(NULL, &mp, V_NOWAIT) == 0) {
 			MNT_ILOCK(mp);
-			asyncflag = mp->mnt_flag & MNT_ASYNC;
-			mp->mnt_flag &= ~MNT_ASYNC;
+			mp->mnt_noasync++;
+			mp->mnt_kern_flag &= ~MNTK_ASYNC;
 			MNT_IUNLOCK(mp);
 			vfs_msync(mp, MNT_NOWAIT);
 			VFS_SYNC(mp, MNT_NOWAIT, td);
 			MNT_ILOCK(mp);
-			mp->mnt_flag |= asyncflag;
+			mp->mnt_noasync--;
+			if ((mp->mnt_flag & MNT_ASYNC) != 0 &&
+			    mp->mnt_noasync == 0)
+				mp->mnt_kern_flag |= MNTK_ASYNC;
 			MNT_IUNLOCK(mp);
 			vn_finished_write(mp);
 		}
diff --git a/sys/nfsclient/nfs_vnops.c b/sys/nfsclient/nfs_vnops.c
index e073de9..c284b1a 100644
--- a/sys/nfsclient/nfs_vnops.c
+++ b/sys/nfsclient/nfs_vnops.c
@@ -1223,7 +1223,7 @@ nfs_writerpc(struct vnode *vp, struct uio *uiop, struct ucred *cred,
 		tsiz -= len;
 	}
 nfsmout:
-	if (vp->v_mount->mnt_flag & MNT_ASYNC)
+	if (vp->v_mount->mnt_kern_flag & MNTK_ASYNC)
 		committed = NFSV3WRITE_FILESYNC;
 	*iomode = committed;
 	if (error)
diff --git a/sys/sys/mount.h b/sys/sys/mount.h
index c7e0db3..70e5097 100644
--- a/sys/sys/mount.h
+++ b/sys/sys/mount.h
@@ -157,6 +157,7 @@ struct mount {
 	int		mnt_writeopcount;	/* (i) write syscalls pending */
 	int		mnt_kern_flag;		/* (i) kernel only flags */
 	u_int		mnt_flag;		/* (i) flags shared with user */
+	u_int		mnt_noasync;		/* (i) # noasync overrides */ 
 	struct vfsoptlist *mnt_opt;		/* current mount options */
 	struct vfsoptlist *mnt_optnew;		/* new options passed to fs */
 	int		mnt_maxsymlinklen;	/* max size of short symlink */
@@ -303,6 +304,7 @@ void          __mnt_vnode_markerfree(struct vnode **mvp, struct mount *mp);
  * with the unmount attempt (used by NFS).
  */
 #define MNTK_UNMOUNTF	0x00000001	/* forced unmount in progress */
+#define MNTK_ASYNC	0x00000002	/* filtered async flag */
 #define MNTK_UNMOUNT	0x01000000	/* unmount in progress */
 #define	MNTK_MWAIT	0x02000000	/* waiting for unmount to finish */
 #define	MNTK_SUSPEND	0x08000000	/* request write suspension */
diff --git a/sys/ufs/ufs/inode.h b/sys/ufs/ufs/inode.h
index 0417f9c..38e2c30 100644
--- a/sys/ufs/ufs/inode.h
+++ b/sys/ufs/ufs/inode.h
@@ -166,7 +166,7 @@ struct indir {
 
 /* Determine if soft dependencies are being done */
 #define DOINGSOFTDEP(vp)	((vp)->v_mount->mnt_flag & MNT_SOFTDEP)
-#define DOINGASYNC(vp)		((vp)->v_mount->mnt_flag & MNT_ASYNC)
+#define DOINGASYNC(vp)		((vp)->v_mount->mnt_kern_flag & MNTK_ASYNC)
 
 /* This overlays the fid structure (see mount.h). */
 struct ufid {