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Index: sys/vm/vm_extern.h
===================================================================
--- sys/vm/vm_extern.h
+++ sys/vm/vm_extern.h
@@ -120,6 +120,7 @@
void vmspace_exitfree(struct proc *);
void vmspace_switch_aio(struct vmspace *);
void vnode_pager_setsize(struct vnode *, vm_ooffset_t);
+void vnode_pager_purge_range(struct vnode *, vm_ooffset_t, vm_ooffset_t);
int vslock(void *, size_t);
void vsunlock(void *, size_t);
struct sf_buf *vm_imgact_map_page(vm_object_t object, vm_ooffset_t offset);
Index: sys/vm/vnode_pager.c
===================================================================
--- sys/vm/vnode_pager.c
+++ sys/vm/vnode_pager.c
@@ -528,6 +528,106 @@
VM_OBJECT_WUNLOCK(object);
}
+/*
+ * Lets the VM system know about the purged range for a file. We toss away any
+ * cached pages in the associated object that are affected by the purge
+ * operation. Content not aligned to page boundaries will be discarded and the
+ * dirty blocks in DEV_BSIZE unit within a page will not be flushed.
+ *
+ * Write lock of the VM object in vnode will be held.
+ */
+void
+vnode_pager_purge_range(
+ struct vnode *vp, vm_ooffset_t startoff, vm_ooffset_t endoff)
+{
+ struct vm_page *m;
+ struct vm_object *object;
+
+ object = vp->v_object;
+ if (object == NULL)
+ return;
+
+ VM_OBJECT_WLOCK(object);
+ vm_object_page_remove(
+ object, OFF_TO_IDX(startoff), OFF_TO_IDX(endoff), 0);
+ if ((startoff & PAGE_MASK) != 0) {
+ m = vm_page_grab(
+ vp->v_object, OFF_TO_IDX(startoff), VM_ALLOC_NOCREAT);
+ if (m != NULL && !vm_page_none_valid(m)) {
+ int base = (int)startoff & PAGE_MASK;
+ int size = PAGE_SIZE - base;
+
+ /*
+ * Clear out partial-page garbage in case
+ * the page has been mapped.
+ */
+ pmap_zero_page_area(m, base, size);
+
+ /*
+ * Update the valid bits to reflect the blocks
+ * that have been zeroed. Some of these valid
+ * bits may have already been set.
+ */
+ vm_page_set_valid_range(m, base, size);
+
+ /*
+ * Round up "base" to the next block boundary so that
+ * the dirty bit for a partially zeroed block is not
+ * cleared.
+ */
+ base = roundup2(base, DEV_BSIZE);
+
+ /*
+ * Clear out partial-page dirty bits.
+ *
+ * note that we do not clear out the valid
+ * bits. This would prevent bogus_page
+ * replacement from working properly.
+ */
+ vm_page_clear_dirty(m, base, PAGE_SIZE - base);
+ }
+ vm_page_xunbusy(m);
+ }
+ if ((endoff & PAGE_MASK) != 0) {
+ m = vm_page_grab(
+ vp->v_object, OFF_TO_IDX(endoff), VM_ALLOC_NOCREAT);
+ if (m != NULL && !vm_page_none_valid(m)) {
+ int end = (int)endoff & PAGE_MASK;
+
+ /*
+ * Clear out partial-page garbage in case
+ * the page has been mapped.
+ */
+ pmap_zero_page_area(m, 0, end);
+
+ /*
+ * Update the valid bits to reflect the blocks
+ * that have been zeroed. Some of these valid
+ * bits may have already been set.
+ */
+ vm_page_set_valid_range(m, 0, end);
+
+ /*
+ * Round down "end" to the previous block boundary so
+ * that the dirty bit for a partially zeroed block is
+ * not cleared.
+ */
+ end = rounddown2(end, DEV_BSIZE);
+
+ /*
+ * Clear out partial-page dirty bits.
+ *
+ * note that we do not clear out the valid
+ * bits. This would prevent bogus_page
+ * replacement from working properly.
+ */
+ vm_page_clear_dirty(m, 0, end);
+ }
+ vm_page_xunbusy(m);
+ }
+ VM_OBJECT_WUNLOCK(object);
+}
+
/*
* calculate the linear (byte) disk address of specified virtual
* file address

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