Remove ENABLE_VFS_IOOPT. It is a long unfinished work-in-progress.

Discussed on:	arch@

12 files changed, 2 insertions, 635 deletions

diff --git a/sys/conf/NOTES b/sys/conf/NOTES
index 3d85184..d4112dc 100644
--- a/sys/conf/NOTES
+++ b/sys/conf/NOTES
@@ -756,21 +756,6 @@ options 	EXT2FS
 # unsuitable for inclusion on machines with untrusted local users.
 options 	VFS_AIO
 
-# Enable the code UFS IO optimization through the VM system.  This allows
-# use VM operations instead of copying operations when possible.
-# 
-# Even with this enabled, actual use of the code is still controlled by the
-# sysctl vfs.ioopt.  0 gives no optimization, 1 gives normal (use VM
-# operations if a request happens to fit), 2 gives agressive optimization
-# (the operations are split to do as much as possible through the VM system.)
-#
-# Enabling this will probably not give an overall speedup except for
-# special workloads.
-#
-# WARNING: Do not enable this, it is known to be broken, and will result
-# in system instability, as well as possible data loss.
-options 	ENABLE_VFS_IOOPT
-
 # Cryptographically secure random number generator; /dev/[u]random
 device		random
 
diff --git a/sys/conf/options b/sys/conf/options
index 5047d70..f5868fe 100644
--- a/sys/conf/options
+++ b/sys/conf/options
@@ -460,7 +460,6 @@ DEBUG_LOCKS		opt_global.h
 DEBUG_VFS_LOCKS		opt_global.h
 LOOKUP_SHARED		opt_global.h
 DIAGNOSTIC		opt_global.h
-ENABLE_VFS_IOOPT	opt_global.h
 INVARIANT_SUPPORT	opt_global.h
 INVARIANTS		opt_global.h
 MCLSHIFT		opt_global.h
diff --git a/sys/kern/kern_subr.c b/sys/kern/kern_subr.c
index a4bbcee..6728e8d 100644
--- a/sys/kern/kern_subr.c
+++ b/sys/kern/kern_subr.c
@@ -59,8 +59,6 @@
 #include <vm/vm_map.h>
 #ifdef ZERO_COPY_SOCKETS
 #include <vm/vm_param.h>
-#endif
-#if defined(ZERO_COPY_SOCKETS) || defined(ENABLE_VFS_IOOPT)
 #include <vm/vm_object.h>
 #endif
 
@@ -197,7 +195,7 @@ out:
 	return (error);
 }
 
-#if defined(ENABLE_VFS_IOOPT) || defined(ZERO_COPY_SOCKETS)
+#ifdef ZERO_COPY_SOCKETS
 /*
  * Experimental support for zero-copy I/O
  */
@@ -209,9 +207,6 @@ userspaceco(void *cp, u_int cnt, struct uio *uio, struct vm_object *obj,
 	int error;
 
 	iov = uio->uio_iov;
-
-#ifdef ZERO_COPY_SOCKETS
-
 	if (uio->uio_rw == UIO_READ) {
 		if ((so_zero_copy_receive != 0)
 		 && (obj != NULL)
@@ -240,43 +235,12 @@ userspaceco(void *cp, u_int cnt, struct uio *uio, struct vm_object *obj,
 			 */
 			if (error != 0)
 				error = copyout(cp, iov->iov_base, cnt);
-#ifdef ENABLE_VFS_IOOPT
-		} else if ((vfs_ioopt != 0)
-		 && ((cnt & PAGE_MASK) == 0)
-		 && ((((intptr_t) iov->iov_base) & PAGE_MASK) == 0)
-		 && ((uio->uio_offset & PAGE_MASK) == 0)
-		 && ((((intptr_t) cp) & PAGE_MASK) == 0)) {
-			error = vm_uiomove(&curproc->p_vmspace->vm_map, obj,
-					   uio->uio_offset, cnt,
-					   (vm_offset_t) iov->iov_base, NULL);
-#endif /* ENABLE_VFS_IOOPT */
 		} else {
 			error = copyout(cp, iov->iov_base, cnt);
 		}
 	} else {
 		error = copyin(iov->iov_base, cp, cnt);
 	}
-#else /* ZERO_COPY_SOCKETS */
-	if (uio->uio_rw == UIO_READ) {
-#ifdef ENABLE_VFS_IOOPT
-		if ((vfs_ioopt != 0)
-		 && ((cnt & PAGE_MASK) == 0)
-		 && ((((intptr_t) iov->iov_base) & PAGE_MASK) == 0)
-		 && ((uio->uio_offset & PAGE_MASK) == 0)
-		 && ((((intptr_t) cp) & PAGE_MASK) == 0)) {
-			error = vm_uiomove(&curproc->p_vmspace->vm_map, obj,
-					   uio->uio_offset, cnt,
-					   (vm_offset_t) iov->iov_base, NULL);
-		} else
-#endif /* ENABLE_VFS_IOOPT */
-		{
-			error = copyout(cp, iov->iov_base, cnt);
-		}
-	} else {
-		error = copyin(iov->iov_base, cp, cnt);
-	}
-#endif /* ZERO_COPY_SOCKETS */
-
 	return (error);
 }
 
@@ -334,75 +298,7 @@ uiomoveco(void *cp, int n, struct uio *uio, struct vm_object *obj,
 	}
 	return (0);
 }
-#endif /* ENABLE_VFS_IOOPT || ZERO_COPY_SOCKETS */
-
-#ifdef ENABLE_VFS_IOOPT
-
-/*
- * Experimental support for zero-copy I/O
- */
-int
-uioread(int n, struct uio *uio, struct vm_object *obj, int *nread)
-{
-	int npagesmoved;
-	struct iovec *iov;
-	u_int cnt, tcnt;
-	int error;
-
-	*nread = 0;
-	if (vfs_ioopt < 2)
-		return 0;
-
-	error = 0;
-
-	while (n > 0 && uio->uio_resid) {
-		iov = uio->uio_iov;
-		cnt = iov->iov_len;
-		if (cnt == 0) {
-			uio->uio_iov++;
-			uio->uio_iovcnt--;
-			continue;
-		}
-		if (cnt > n)
-			cnt = n;
-
-		if ((uio->uio_segflg == UIO_USERSPACE) &&
-			((((intptr_t) iov->iov_base) & PAGE_MASK) == 0) &&
-				 ((uio->uio_offset & PAGE_MASK) == 0) ) {
-
-			if (cnt < PAGE_SIZE)
-				break;
-
-			cnt &= ~PAGE_MASK;
-
-			if (ticks - PCPU_GET(switchticks) >= hogticks)
-				uio_yield();
-			error = vm_uiomove(&curproc->p_vmspace->vm_map, obj,
-						uio->uio_offset, cnt,
-						(vm_offset_t) iov->iov_base, &npagesmoved);
-
-			if (npagesmoved == 0)
-				break;
-
-			tcnt = npagesmoved * PAGE_SIZE;
-			cnt = tcnt;
-
-			if (error)
-				break;
-
-			iov->iov_base = (char *)iov->iov_base + cnt;
-			iov->iov_len -= cnt;
-			uio->uio_resid -= cnt;
-			uio->uio_offset += cnt;
-			*nread += cnt;
-			n -= cnt;
-		} else {
-			break;
-		}
-	}
-	return error;
-}
-#endif /* ENABLE_VFS_IOOPT */
+#endif /* ZERO_COPY_SOCKETS */
 
 /*
  * Give next character to user as result of read.
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 7e21555..5f4b678 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -130,12 +130,6 @@ SYSCTL_INT(_vfs, OID_AUTO, reassignbufcalls, CTLFLAG_RW, &reassignbufcalls, 0, "
 static int nameileafonly;
 SYSCTL_INT(_vfs, OID_AUTO, nameileafonly, CTLFLAG_RW, &nameileafonly, 0, "");
 
-#ifdef ENABLE_VFS_IOOPT
-/* See NOTES for a description of this setting. */
-int vfs_ioopt;
-SYSCTL_INT(_vfs, OID_AUTO, ioopt, CTLFLAG_RW, &vfs_ioopt, 0, "");
-#endif
-
 /*
  * Cache for the mount type id assigned to NFS.  This is used for
  * special checks in nfs/nfs_nqlease.c and vm/vnode_pager.c.
diff --git a/sys/sys/uio.h b/sys/sys/uio.h
index 8604360..e70e9f6 100644
--- a/sys/sys/uio.h
+++ b/sys/sys/uio.h
@@ -88,7 +88,6 @@ struct vm_object;
 void	uio_yield(void);
 int	uiomove(void *, int, struct uio *);
 int	uiomoveco(void *, int, struct uio *, struct vm_object *, int);
-int	uioread(int, struct uio *, struct vm_object *, int *);
 int	copyinfrom(const void *src, void *dst, size_t len, int seg);
 int	copyinstrfrom(const void *src, void *dst, size_t len,
 	    size_t *copied, int seg);
diff --git a/sys/ufs/ffs/ffs_vnops.c b/sys/ufs/ffs/ffs_vnops.c
index 9b39812..cc6debc 100644
--- a/sys/ufs/ffs/ffs_vnops.c
+++ b/sys/ufs/ffs/ffs_vnops.c
@@ -389,45 +389,6 @@ ffs_read(ap)
 		vm_object_reference(object);
 	}
 
-#ifdef ENABLE_VFS_IOOPT
-	/*
-	 * If IO optimisation is turned on,
-	 * and we are NOT a VM based IO request, 
-	 * (i.e. not headed for the buffer cache)
-	 * but there IS a vm object associated with it.
-	 */
-	if ((ioflag & IO_VMIO) == 0 && (vfs_ioopt > 1) && object) {
-		int nread, toread;
-
-		toread = uio->uio_resid;
-		if (toread > bytesinfile)
-			toread = bytesinfile;
-		if (toread >= PAGE_SIZE) {
-			/*
-			 * Then if it's at least a page in size, try 
-			 * get the data from the object using vm tricks
-			 */
-			error = uioread(toread, uio, object, &nread);
-			if ((uio->uio_resid == 0) || (error != 0)) {
-				/*
-				 * If we finished or there was an error
-				 * then finish up (the reference previously
-				 * obtained on object must be released).
-				 */
-				if ((error == 0 ||
-				    uio->uio_resid != orig_resid) &&
-				    (vp->v_mount->mnt_flag & MNT_NOATIME) == 0)
-					ip->i_flag |= IN_ACCESS;
-
-				if (object) {
-					vm_object_vndeallocate(object);
-				}
-				return error;
-			}
-		}
-	}
-#endif
-
 	/*
 	 * Ok so we couldn't do it all in one vm trick...
 	 * so cycle around trying smaller bites..
@@ -435,52 +396,6 @@ ffs_read(ap)
 	for (error = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) {
 		if ((bytesinfile = ip->i_size - uio->uio_offset) <= 0)
 			break;
-#ifdef ENABLE_VFS_IOOPT
-		if ((ioflag & IO_VMIO) == 0 && (vfs_ioopt > 1) && object) {
-			/*
-			 * Obviously we didn't finish above, but we
-			 * didn't get an error either. Try the same trick again.
-			 * but this time we are looping.
-			 */
-			int nread, toread;
-			toread = uio->uio_resid;
-			if (toread > bytesinfile)
-				toread = bytesinfile;
-
-			/*
-			 * Once again, if there isn't enough for a
-			 * whole page, don't try optimising.
-			 */
-			if (toread >= PAGE_SIZE) {
-				error = uioread(toread, uio, object, &nread);
-				if ((uio->uio_resid == 0) || (error != 0)) {
-					/*
-					 * If we finished or there was an 
-					 * error then finish up (the reference
-					 * previously obtained on object must 
-					 * be released).
-					 */
-					if ((error == 0 ||
-					    uio->uio_resid != orig_resid) &&
-					    (vp->v_mount->mnt_flag &
-					    MNT_NOATIME) == 0)
-						ip->i_flag |= IN_ACCESS;
-					if (object) {
-						vm_object_vndeallocate(object);
-					}
-					return error;
-				}
-				/*
-				 * To get here we didnt't finish or err.
-				 * If we did get some data,
-				 * loop to try another bite.
-				 */
-				if (nread > 0) {
-					continue;
-				}
-			}
-		}
-#endif
 
 		lbn = lblkno(fs, uio->uio_offset);
 		nextlbn = lbn + 1;
@@ -575,22 +490,6 @@ ffs_read(ap)
 			xfersize = size;
 		}
 
-#ifdef ENABLE_VFS_IOOPT
-		if (vfs_ioopt && object &&
-		    (bp->b_flags & B_VMIO) &&
-		    ((blkoffset & PAGE_MASK) == 0) &&
-		    ((xfersize & PAGE_MASK) == 0)) {
-			/*
-			 * If VFS IO  optimisation is turned on,
-			 * and it's an exact page multiple
-			 * And a normal VM based op,
-			 * then use uiomiveco()
-			 */
-			error =
-				uiomoveco((char *)bp->b_data + blkoffset,
-					(int)xfersize, uio, object, 0);
-		} else 
-#endif
 		{
 			/*
 			 * otherwise use the general form
@@ -755,13 +654,6 @@ ffs_write(ap)
 	if ((ioflag & IO_SYNC) && !DOINGASYNC(vp))
 		flags |= IO_SYNC;
 
-#ifdef ENABLE_VFS_IOOPT
-	if (object && (object->flags & OBJ_OPT)) {
-		vm_freeze_copyopts(object,
-			OFF_TO_IDX(uio->uio_offset),
-			OFF_TO_IDX(uio->uio_offset + uio->uio_resid + PAGE_MASK));
-	}
-#endif
 	for (error = 0; uio->uio_resid > 0;) {
 		lbn = lblkno(fs, uio->uio_offset);
 		blkoffset = blkoff(fs, uio->uio_offset);
diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c
index abb9ef3..e443a00 100644
--- a/sys/vm/vm_fault.c
+++ b/sys/vm/vm_fault.c
@@ -280,13 +280,6 @@ RetryFault:;
 	fs.vp = vnode_pager_lock(fs.first_object);
 	vm_object_pip_add(fs.first_object, 1);
 
-#ifdef ENABLE_VFS_IOOPT
-	if ((fault_type & VM_PROT_WRITE) &&
-		(fs.first_object->type == OBJT_VNODE)) {
-		vm_freeze_copyopts(fs.first_object,
-			fs.first_pindex, fs.first_pindex + 1);
-	}
-#endif
 	fs.lookup_still_valid = TRUE;
 
 	if (wired)
diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
index cd3b2e7..33e819d 100644
--- a/sys/vm/vm_map.c
+++ b/sys/vm/vm_map.c
@@ -2879,255 +2879,6 @@ vm_map_lookup_done(vm_map_t map, vm_map_entry_t entry)
 	vm_map_unlock_read(map);
 }
 
-#ifdef ENABLE_VFS_IOOPT
-/*
- * Experimental support for zero-copy I/O
- *
- * Implement uiomove with VM operations.  This handles (and collateral changes)
- * support every combination of source object modification, and COW type
- * operations.
- */
-int
-vm_uiomove(
-	vm_map_t mapa,
-	vm_object_t srcobject,
-	off_t cp,
-	int cnta,
-	vm_offset_t uaddra,
-	int *npages)
-{
-	vm_map_t map;
-	vm_object_t first_object, oldobject, object;
-	vm_map_entry_t entry;
-	vm_prot_t prot;
-	boolean_t wired;
-	int tcnt, rv;
-	vm_offset_t uaddr, start, end, tend;
-	vm_pindex_t first_pindex, oindex;
-	vm_size_t osize;
-	off_t ooffset;
-	int cnt;
-
-	GIANT_REQUIRED;
-
-	if (npages)
-		*npages = 0;
-
-	cnt = cnta;
-	uaddr = uaddra;
-
-	while (cnt > 0) {
-		map = mapa;
-
-		if ((vm_map_lookup(&map, uaddr,
-			VM_PROT_READ, &entry, &first_object,
-			&first_pindex, &prot, &wired)) != KERN_SUCCESS) {
-			return EFAULT;
-		}
-
-		vm_map_clip_start(map, entry, uaddr);
-
-		tcnt = cnt;
-		tend = uaddr + tcnt;
-		if (tend > entry->end) {
-			tcnt = entry->end - uaddr;
-			tend = entry->end;
-		}
-
-		vm_map_clip_end(map, entry, tend);
-
-		start = entry->start;
-		end = entry->end;
-
-		osize = atop(tcnt);
-
-		oindex = OFF_TO_IDX(cp);
-		if (npages) {
-			vm_size_t idx;
-			for (idx = 0; idx < osize; idx++) {
-				vm_page_t m;
-				if ((m = vm_page_lookup(srcobject, oindex + idx)) == NULL) {
-					vm_map_lookup_done(map, entry);
-					return 0;
-				}
-				/*
-				 * disallow busy or invalid pages, but allow
-				 * m->busy pages if they are entirely valid.
-				 */
-				if ((m->flags & PG_BUSY) ||
-					((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL)) {
-					vm_map_lookup_done(map, entry);
-					return 0;
-				}
-			}
-		}
-
-/*
- * If we are changing an existing map entry, just redirect
- * the object, and change mappings.
- */
-		if ((first_object->type == OBJT_VNODE) &&
-			((oldobject = entry->object.vm_object) == first_object)) {
-
-			if ((entry->offset != cp) || (oldobject != srcobject)) {
-				/*
-   				* Remove old window into the file
-   				*/
-				vm_page_lock_queues();
-				pmap_remove(map->pmap, uaddr, tend);
-				vm_page_unlock_queues();
-
-				/*
-   				* Force copy on write for mmaped regions
-   				*/
-				vm_object_pmap_copy_1 (srcobject, oindex, oindex + osize);
-
-				/*
-   				* Point the object appropriately
-   				*/
-				if (oldobject != srcobject) {
-
-				/*
-   				* Set the object optimization hint flag
-   				*/
-					vm_object_set_flag(srcobject, OBJ_OPT);
-					vm_object_reference(srcobject);
-					entry->object.vm_object = srcobject;
-
-					if (oldobject) {
-						vm_object_deallocate(oldobject);
-					}
-				}
-
-				entry->offset = cp;
-				map->timestamp++;
-			} else {
-				vm_page_lock_queues();
-				pmap_remove(map->pmap, uaddr, tend);
-				vm_page_unlock_queues();
-			}
-
-		} else if ((first_object->ref_count == 1) &&
-			(first_object->size == osize) &&
-			((first_object->type == OBJT_DEFAULT) ||
-				(first_object->type == OBJT_SWAP)) ) {
-
-			oldobject = first_object->backing_object;
-
-			if ((first_object->backing_object_offset != cp) ||
-				(oldobject != srcobject)) {
-				/*
-   				* Remove old window into the file
-   				*/
-				vm_page_lock_queues();
-				pmap_remove(map->pmap, uaddr, tend);
-				vm_page_unlock_queues();
-
-				/*
-				 * Remove unneeded old pages
-				 */
-				vm_object_lock(first_object);
-				vm_object_page_remove(first_object, 0, 0, 0);
-				vm_object_unlock(first_object);
-
-				/*
-				 * Invalidate swap space
-				 */
-				if (first_object->type == OBJT_SWAP) {
-					swap_pager_freespace(first_object,
-						0,
-						first_object->size);
-				}
-
-				/*
-   				 * Force copy on write for mmaped regions
-   				 */
-				vm_object_pmap_copy_1 (srcobject, oindex, oindex + osize);
-
-				/*
-   				 * Point the object appropriately
-   				 */
-				if (oldobject != srcobject) {
-					/*
-   					 * Set the object optimization hint flag
-   					 */
-					vm_object_set_flag(srcobject, OBJ_OPT);
-					vm_object_reference(srcobject);
-
-					if (oldobject) {
-						TAILQ_REMOVE(&oldobject->shadow_head,
-							first_object, shadow_list);
-						oldobject->shadow_count--;
-						/* XXX bump generation? */
-						vm_object_deallocate(oldobject);
-					}
-
-					TAILQ_INSERT_TAIL(&srcobject->shadow_head,
-						first_object, shadow_list);
-					srcobject->shadow_count++;
-					/* XXX bump generation? */
-
-					first_object->backing_object = srcobject;
-				}
-				first_object->backing_object_offset = cp;
-				map->timestamp++;
-			} else {
-				vm_page_lock_queues();
-				pmap_remove(map->pmap, uaddr, tend);
-				vm_page_unlock_queues();
-			}
-/*
- * Otherwise, we have to do a logical mmap.
- */
-		} else {
-
-			vm_object_set_flag(srcobject, OBJ_OPT);
-			vm_object_reference(srcobject);
-
-			vm_page_lock_queues();
-			pmap_remove(map->pmap, uaddr, tend);
-			vm_page_unlock_queues();
-
-			vm_object_pmap_copy_1 (srcobject, oindex, oindex + osize);
-			vm_map_lock_upgrade(map);
-
-			if (entry == &map->header) {
-				map->first_free = &map->header;
-			} else if (map->first_free->start >= start) {
-				map->first_free = entry->prev;
-			}
-
-			vm_map_entry_delete(map, entry);
-
-			object = srcobject;
-			ooffset = cp;
-
-			rv = vm_map_insert(map, object, ooffset, start, tend,
-				VM_PROT_ALL, VM_PROT_ALL, MAP_COPY_ON_WRITE);
-
-			if (rv != KERN_SUCCESS)
-				panic("vm_uiomove: could not insert new entry: %d", rv);
-		}
-
-/*
- * Map the window directly, if it is already in memory
- */
-		pmap_object_init_pt(map->pmap, uaddr,
-			srcobject, oindex, tcnt, 0);
-
-		map->timestamp++;
-		vm_map_unlock(map);
-
-		cnt -= tcnt;
-		uaddr += tcnt;
-		cp += tcnt;
-		if (npages)
-			*npages += osize;
-	}
-	return 0;
-}
-#endif
-
 #include "opt_ddb.h"
 #ifdef DDB
 #include <sys/kernel.h>
diff --git a/sys/vm/vm_map.h b/sys/vm/vm_map.h
index 3809d06..eef9a48 100644
--- a/sys/vm/vm_map.h
+++ b/sys/vm/vm_map.h
@@ -322,6 +322,5 @@ int vm_map_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end,
 int vm_map_wire(vm_map_t map, vm_offset_t start, vm_offset_t end,
     boolean_t user_wire);
 int vmspace_swap_count (struct vmspace *vmspace);
-int vm_uiomove(vm_map_t, vm_object_t, off_t, int, vm_offset_t, int *);
 #endif				/* _KERNEL */
 #endif				/* _VM_MAP_ */
diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 2fe605d..b51987b 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -407,9 +407,6 @@ vm_object_vndeallocate(vm_object_t object)
 	if (object->ref_count == 0) {
 		mp_fixme("Unlocked vflag access.");
 		vp->v_vflag &= ~VV_TEXT;
-#ifdef ENABLE_VFS_IOOPT
-		vm_object_clear_flag(object, OBJ_OPT);
-#endif
 	}
 	/*
 	 * vrele may need a vop lock
@@ -502,10 +499,6 @@ doterm:
 		if (temp) {
 			TAILQ_REMOVE(&temp->shadow_head, object, shadow_list);
 			temp->shadow_count--;
-#ifdef ENABLE_VFS_IOOPT
-			if (temp->ref_count == 0)
-				vm_object_clear_flag(temp, OBJ_OPT);
-#endif
 			temp->generation++;
 			object->backing_object = NULL;
 		}
@@ -556,12 +549,6 @@ vm_object_terminate(vm_object_t object)
 	if (object->type == OBJT_VNODE) {
 		struct vnode *vp;
 
-#ifdef ENABLE_VFS_IOOPT
-		/*
-		 * Freeze optimized copies.
-		 */
-		vm_freeze_copyopts(object, 0, object->size);
-#endif
 		/*
 		 * Clean pages and flush buffers.
 		 */
@@ -937,39 +924,6 @@ vm_object_page_collect_flush(vm_object_t object, vm_page_t p, int curgeneration,
 	return(maxf + 1);
 }
 
-#ifdef ENABLE_VFS_IOOPT
-/*
- * Same as vm_object_pmap_copy, except range checking really
- * works, and is meant for small sections of an object.
- *
- * This code protects resident pages by making them read-only
- * and is typically called on a fork or split when a page
- * is converted to copy-on-write.  
- *
- * NOTE: If the page is already at VM_PROT_NONE, calling
- * pmap_page_protect will have no effect.
- */
-void
-vm_object_pmap_copy_1(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
-{
-	vm_pindex_t idx;
-	vm_page_t p;
-
-	GIANT_REQUIRED;
-
-	if (object == NULL || (object->flags & OBJ_WRITEABLE) == 0)
-		return;
-	vm_page_lock_queues();
-	for (idx = start; idx < end; idx++) {
-		p = vm_page_lookup(object, idx);
-		if (p == NULL)
-			continue;
-		pmap_page_protect(p, VM_PROT_READ);
-	}
-	vm_page_unlock_queues();
-}
-#endif
-
 /*
  *	vm_object_madvise:
  *
@@ -1852,94 +1806,6 @@ vm_object_set_writeable_dirty(vm_object_t object)
 	}
 }
 
-#ifdef ENABLE_VFS_IOOPT
-/*
- * Experimental support for zero-copy I/O
- *
- * Performs the copy_on_write operations necessary to allow the virtual copies
- * into user space to work.  This has to be called for write(2) system calls
- * from other processes, file unlinking, and file size shrinkage.
- */
-void
-vm_freeze_copyopts(vm_object_t object, vm_pindex_t froma, vm_pindex_t toa)
-{
-	int rv;
-	vm_object_t robject;
-	vm_pindex_t idx;
-
-	GIANT_REQUIRED;
-	if ((object == NULL) ||
-		((object->flags & OBJ_OPT) == 0))
-		return;
-
-	if (object->shadow_count > object->ref_count)
-		panic("vm_freeze_copyopts: sc > rc");
-
-	while ((robject = TAILQ_FIRST(&object->shadow_head)) != NULL) {
-		vm_pindex_t bo_pindex;
-		vm_page_t m_in, m_out;
-
-		bo_pindex = OFF_TO_IDX(robject->backing_object_offset);
-
-		vm_object_reference(robject);
-
-		vm_object_pip_wait(robject, "objfrz");
-
-		if (robject->ref_count == 1) {
-			vm_object_deallocate(robject);
-			continue;
-		}
-
-		vm_object_pip_add(robject, 1);
-
-		for (idx = 0; idx < robject->size; idx++) {
-
-			m_out = vm_page_grab(robject, idx,
-						VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
-
-			if (m_out->valid == 0) {
-				m_in = vm_page_grab(object, bo_pindex + idx,
-						VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
-				vm_page_lock_queues();
-				if (m_in->valid == 0) {
-					vm_page_unlock_queues();
-					rv = vm_pager_get_pages(object, &m_in, 1, 0);
-					if (rv != VM_PAGER_OK) {
-						printf("vm_freeze_copyopts: cannot read page from file: %lx\n", (long)m_in->pindex);
-						continue;
-					}
-					vm_page_lock_queues();
-					vm_page_deactivate(m_in);
-				}
-
-				pmap_remove_all(m_in);
-				vm_page_unlock_queues();
-				pmap_copy_page(m_in, m_out);
-				vm_page_lock_queues();
-				m_out->valid = m_in->valid;
-				vm_page_dirty(m_out);
-				vm_page_activate(m_out);
-				vm_page_wakeup(m_in);
-			} else
-				vm_page_lock_queues();
-			vm_page_wakeup(m_out);
-			vm_page_unlock_queues();
-		}
-
-		object->shadow_count--;
-		object->ref_count--;
-		TAILQ_REMOVE(&object->shadow_head, robject, shadow_list);
-		robject->backing_object = NULL;
-		robject->backing_object_offset = 0;
-
-		vm_object_pip_wakeup(robject);
-		vm_object_deallocate(robject);
-	}
-
-	vm_object_clear_flag(object, OBJ_OPT);
-}
-#endif
-
 #include "opt_ddb.h"
 #ifdef DDB
 #include <sys/kernel.h>
diff --git a/sys/vm/vm_object.h b/sys/vm/vm_object.h
index 1716e35..467d7f0 100644
--- a/sys/vm/vm_object.h
+++ b/sys/vm/vm_object.h
@@ -151,7 +151,6 @@ struct vm_object {
 #define	OBJ_WRITEABLE	0x0080		/* object has been made writable */
 #define OBJ_MIGHTBEDIRTY 0x0100		/* object might be dirty */
 #define OBJ_CLEANING	0x0200
-#define OBJ_OPT		0x1000		/* I/O optimization */
 #define	OBJ_ONEMAPPING	0x2000		/* One USE (a single, non-forked) mapping flag */
 
 #define IDX_TO_OFF(idx) (((vm_ooffset_t)(idx)) << PAGE_SHIFT)
@@ -176,8 +175,6 @@ extern vm_object_t kmem_object;
 #define	vm_object_unlock(object) \
 	mtx_unlock((object) == kmem_object ? &kmem_object->mtx : &Giant)
 
-void vm_freeze_copyopts(vm_object_t, vm_pindex_t, vm_pindex_t);
-
 void vm_object_set_flag(vm_object_t object, u_short bits);
 void vm_object_clear_flag(vm_object_t object, u_short bits);
 void vm_object_pip_add(vm_object_t object, short i);
@@ -199,7 +196,6 @@ void vm_object_set_writeable_dirty (vm_object_t);
 void vm_object_init (void);
 void vm_object_page_clean (vm_object_t, vm_pindex_t, vm_pindex_t, boolean_t);
 void vm_object_page_remove (vm_object_t, vm_pindex_t, vm_pindex_t, boolean_t);
-void vm_object_pmap_copy_1 (vm_object_t, vm_pindex_t, vm_pindex_t);
 void vm_object_reference (vm_object_t);
 void vm_object_shadow (vm_object_t *, vm_ooffset_t *, vm_size_t);
 void vm_object_split(vm_map_entry_t);
diff --git a/sys/vm/vnode_pager.c b/sys/vm/vnode_pager.c
index f061ccb..5522bcb 100644
--- a/sys/vm/vnode_pager.c
+++ b/sys/vm/vnode_pager.c
@@ -307,9 +307,6 @@ vnode_pager_setsize(vp, nsize)
 	 * File has shrunk. Toss any cached pages beyond the new EOF.
 	 */
 	if (nsize < object->un_pager.vnp.vnp_size) {
-#ifdef ENABLE_VFS_IOOPT
-		vm_freeze_copyopts(object, OFF_TO_IDX(nsize), object->size);
-#endif
 		if (nobjsize < object->size) {
 			vm_object_lock(object);
 			vm_object_page_remove(object, nobjsize, object->size,