When attempt is made to suspend a filesystem that is already syspended,

wait until the current suspension is lifted instead of silently returning
success immediately. The consequences of calling vfs_write() resume when
not owning the suspension are not well-defined at best.

Add the vfs_susp_clean() mount method to be called from
vfs_write_resume(). Set it to process_deferred_inactive() for ffs, and
stop calling it manually.

Add the thread flag TDP_IGNSUSP that allows to bypass the suspension
point in the vn_start_write. It is intended for use by VFS in the
situations where the suspender want to do some i/o requiring calls to
vn_start_write(), and this i/o cannot be done later.

Reviewed by:	tegge
In collaboration with:	pho
MFC after:	 1 month

3 files changed, 7 insertions, 2 deletions

diff --git a/sys/ufs/ffs/ffs_extern.h b/sys/ufs/ffs/ffs_extern.h
index d5dfa12..4a2f3a2 100644
--- a/sys/ufs/ffs/ffs_extern.h
+++ b/sys/ufs/ffs/ffs_extern.h
@@ -80,6 +80,7 @@ void	ffs_snapremove(struct vnode *vp);
 int	ffs_snapshot(struct mount *mp, char *snapfile);
 void	ffs_snapshot_mount(struct mount *mp);
 void	ffs_snapshot_unmount(struct mount *mp);
+void	process_deferred_inactive(struct mount *mp);
 int	ffs_syncvnode(struct vnode *vp, int waitfor);
 int	ffs_truncate(struct vnode *, off_t, int, struct ucred *, struct thread *);
 int	ffs_update(struct vnode *, int);
diff --git a/sys/ufs/ffs/ffs_snapshot.c b/sys/ufs/ffs/ffs_snapshot.c
index c367d66..fab6798 100644
--- a/sys/ufs/ffs/ffs_snapshot.c
+++ b/sys/ufs/ffs/ffs_snapshot.c
@@ -167,7 +167,6 @@ static int snapacct_ufs2(struct vnode *, ufs2_daddr_t *, ufs2_daddr_t *,
 static int mapacct_ufs2(struct vnode *, ufs2_daddr_t *, ufs2_daddr_t *,
     struct fs *, ufs_lbn_t, int);
 static int readblock(struct vnode *vp, struct buf *, ufs2_daddr_t);
-static void process_deferred_inactive(struct mount *);
 static void try_free_snapdata(struct vnode *devvp);
 static struct snapdata *ffs_snapdata_acquire(struct vnode *devvp);
 static int ffs_bp_snapblk(struct vnode *, struct buf *);
@@ -2375,12 +2374,14 @@ readblock(vp, bp, lbn)
 	return (bp->b_error);
 }
 
+#endif
+
 /*
  * Process file deletes that were deferred by ufs_inactive() due to
  * the file system being suspended. Transfer IN_LAZYACCESS into
  * IN_MODIFIED for vnodes that were accessed during suspension.
  */
-static void
+void
 process_deferred_inactive(struct mount *mp)
 {
 	struct vnode *vp, *mvp;
@@ -2453,6 +2454,8 @@ process_deferred_inactive(struct mount *mp)
 	vn_finished_secondary_write(mp);
 }
 
+#ifndef NO_FFS_SNAPSHOT
+
 static struct snapdata *
 ffs_snapdata_alloc(void)
 {
diff --git a/sys/ufs/ffs/ffs_vfsops.c b/sys/ufs/ffs/ffs_vfsops.c
index 93e0b48..86b3f60 100644
--- a/sys/ufs/ffs/ffs_vfsops.c
+++ b/sys/ufs/ffs/ffs_vfsops.c
@@ -105,6 +105,7 @@ static struct vfsops ufs_vfsops = {
 	.vfs_uninit =		ffs_uninit,
 	.vfs_unmount =		ffs_unmount,
 	.vfs_vget =		ffs_vget,
+	.vfs_susp_clean =	process_deferred_inactive,
 };
 
 VFS_SET(ufs_vfsops, ufs, 0);