bitkeeper revision 1.160.1.1 (3e8c846fQSuOz1Dd8MgUzwG5rj3bDQ)

Many files:
  Free DOM0 kernel memory to Xen allocation pool after DOM0 is created. Fixed page-type handling -- we now correctly flush TLB if a page is unpinned after a disk read and refcnt falls to zero.

1 files changed, 19 insertions, 4 deletions

diff --git a/xen/drivers/block/xen_block.c b/xen/drivers/block/xen_block.c
index 156dcbb94c..8901ee59fb 100644
--- a/xen/drivers/block/xen_block.c
+++ b/xen/drivers/block/xen_block.c
@@ -277,7 +277,8 @@ static int __buffer_is_valid(struct task_struct *p,
 
         /* If reading into the frame, the frame must be writeable. */
         if ( writeable_buffer &&
-             ((page->flags & PG_type_mask) != PGT_writeable_page) )
+             ((page->flags & PG_type_mask) != PGT_writeable_page) &&
+             (page->type_count != 0) )
         {
             DPRINTK("non-writeable page passed for block read\n");
             goto out;
@@ -301,7 +302,16 @@ static void __lock_buffer(unsigned long buffer,
           pfn++ )
     {
         page = frame_table + pfn;
-        if ( writeable_buffer ) get_page_type(page);
+        if ( writeable_buffer )
+        {
+            if ( page->type_count == 0 )
+            {
+                page->flags &= ~PG_type_mask;
+                /* NB. This ref alone won't cause a TLB flush. */
+                page->flags |= PGT_writeable_page | PG_noflush;
+            }
+            get_page_type(page);
+        }
         get_page_tot(page);
     }
 }
@@ -320,8 +330,13 @@ static void unlock_buffer(struct task_struct *p,
           pfn++ )
     {
         page = frame_table + pfn;
-        if ( writeable_buffer && (put_page_type(page) == 0) )
-            page->flags &= ~PG_type_mask;
+        if ( writeable_buffer &&
+             (put_page_type(page) == 0) &&
+             !(page->flags & PG_noflush) )
+        {
+            __flush_tlb();
+        }
+        page->flags &= ~PG_noflush;
         put_page_tot(page);
     }
     spin_unlock_irqrestore(&p->page_lock, flags);