New option: NO_FFS_SNAPSHOT. I did this in p4 about the same time

that NetBSD implemented it independently of them (don't know which one
was actually first).  This saves about 24k for those times you don't
need snapshot support (like when running off a ram disk, or in an
embedded environment where size matters).

2 files changed, 63 insertions, 0 deletions

diff --git a/sys/conf/options b/sys/conf/options
index 81844ce..3ed3901 100644
--- a/sys/conf/options
+++ b/sys/conf/options
@@ -213,6 +213,11 @@ UDF_ICONV	opt_dontuse.h
 # otherwise a STUB module will be compiled in.
 SOFTUPDATES	opt_ffs.h
 
+# On small, embedded systems, it can be useful to turn off support for
+# snapshots.  It saves about 30-40k for a feature that would be lightly
+# used, if it is used at all.
+NO_FFS_SNAPSHOT	opt_ffs.h
+
 # Enabling this option turns on support for Access Control Lists in UFS,
 # which can be used to support high security configurations.  Depends on
 # UFS_EXTATTR.
diff --git a/sys/ufs/ffs/ffs_snapshot.c b/sys/ufs/ffs/ffs_snapshot.c
index 98a1f23..c64a1e3 100644
--- a/sys/ufs/ffs/ffs_snapshot.c
+++ b/sys/ufs/ffs/ffs_snapshot.c
@@ -66,6 +66,62 @@ __FBSDID("$FreeBSD$");
 #define KERNCRED thread0.td_ucred
 #define DEBUG 1
 
+#include "opt_ffs.h"
+
+#ifdef NO_FFS_SNAPSHOT
+int
+ffs_snapshot(mp, snapfile)
+	struct mount *mp;
+	char *snapfile;
+{
+	return (EINVAL);
+}
+
+int
+ffs_snapblkfree(fs, devvp, bno, size, inum)
+	struct fs *fs;
+	struct vnode *devvp;
+	ufs2_daddr_t bno;
+	long size;
+	ino_t inum;
+{
+	return (EINVAL);
+}
+
+void
+ffs_snapremove(vp)
+	struct vnode *vp;
+{
+}
+
+void
+ffs_snapshot_mount(mp)
+	struct mount *mp;
+{
+}
+
+void
+ffs_snapshot_unmount(mp)
+	struct mount *mp;
+{
+}
+
+void
+ffs_snapgone(ip)
+	struct inode *ip;
+{
+}
+
+int
+ffs_copyonwrite(devvp, bp)
+	struct vnode *devvp;
+	struct buf *bp;
+{
+	return (EINVAL);
+}
+
+#else
+
 TAILQ_HEAD(snaphead, inode);
 
 struct snapdata {
@@ -2171,3 +2227,5 @@ readblock(vp, bp, lbn)
 	g_destroy_bio(bip);
 	return (bp->b_error);
 }
+
+#endif