[PATCH] execute-in-place fixes

This patch includes feedback from Andrew and Christoph. Thanks for
taking time to review.

Use of empty_zero_page was eliminated to fix compilation for architectures
that don't have it.

This patch removes setting pages up-to-date in ext2_get_xip_page and all
bug checks to verify that the page is indeed up to date.  Setting the page
state on mapping to userland is bogus.  None of the code patchs involved
with these pages in mm cares about the page state.

still on my ToDo list: identify a place outside second extended where
__inode_direct_access should reside

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 8 insertions, 15 deletions

diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index 4553b2c5aab4..8c199f537732 100644
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -68,13 +68,12 @@ do_xip_mapping_read(struct address_space *mapping,
                 if (unlikely(IS_ERR(page))) {
                         if (PTR_ERR(page) == -ENODATA) {
                                 /* sparse */
-                                page = virt_to_page(empty_zero_page);
+                                page = ZERO_PAGE(0);
                         } else {
                                 desc->error = PTR_ERR(page);
                                 goto out;
                         }
-                } else
-                        BUG_ON(!PageUptodate(page));
+                }
 
                 /* If users can be writing to this page using arbitrary
                  * virtual addresses, take care about potential aliasing
@@ -84,8 +83,7 @@ do_xip_mapping_read(struct address_space *mapping,
                         flush_dcache_page(page);
 
                 /*
-                 * Ok, we have the page, and it's up-to-date, so
-                 * now we can copy it to user space...
+                 * Ok, we have the page, so now we can copy it to user space...
                  *
                  * The actor routine returns how many bytes were actually used..
                  * NOTE! This may not be the same as how much of a user buffer
@@ -164,7 +162,7 @@ EXPORT_SYMBOL_GPL(xip_file_sendfile);
  * xip_write
  *
  * This function walks all vmas of the address_space and unmaps the
- * empty_zero_page when found at pgoff. Should it go in rmap.c?
+ * ZERO_PAGE when found at pgoff. Should it go in rmap.c?
  */
 static void
 __xip_unmap (struct address_space * mapping,
@@ -187,7 +185,7 @@ __xip_unmap (struct address_space * mapping,
                  * We need the page_table_lock to protect us from page faults,
                  * munmap, fork, etc...
                  */
-                pte = page_check_address(virt_to_page(empty_zero_page), mm,
+                pte = page_check_address(ZERO_PAGE(address), mm,
                                          address);
                 if (!IS_ERR(pte)) {
                         /* Nuke the page table entry. */
@@ -230,7 +228,6 @@ xip_file_nopage(struct vm_area_struct * area,
 
         page = mapping->a_ops->get_xip_page(mapping, pgoff*(PAGE_SIZE/512), 0);
         if (!IS_ERR(page)) {
-                BUG_ON(!PageUptodate(page));
                 return page;
         }
         if (PTR_ERR(page) != -ENODATA)
@@ -245,12 +242,11 @@ xip_file_nopage(struct vm_area_struct * area,
                         pgoff*(PAGE_SIZE/512), 1);
                 if (IS_ERR(page))
                         return NULL;
-                BUG_ON(!PageUptodate(page));
                 /* unmap page at pgoff from all other vmas */
                 __xip_unmap(mapping, pgoff);
         } else {
-                /* not shared and writable, use empty_zero_page */
-                page = virt_to_page(empty_zero_page);
+                /* not shared and writable, use ZERO_PAGE() */
+                page = ZERO_PAGE(address);
         }
 
         return page;
@@ -319,8 +315,6 @@ __xip_file_write(struct file *filp, const char __user *buf,
                         break;
                 }
 
-                BUG_ON(!PageUptodate(page));
-
                 copied = filemap_copy_from_user(page, offset, buf, bytes);
                 flush_dcache_page(page);
                 if (likely(copied > 0)) {
@@ -435,8 +429,7 @@ xip_truncate_page(struct address_space *mapping, loff_t from)
                         return 0;
                 else
                         return PTR_ERR(page);
-        } else
-                BUG_ON(!PageUptodate(page));
+        }
         kaddr = kmap_atomic(page, KM_USER0);
         memset(kaddr + offset, 0, length);
         kunmap_atomic(kaddr, KM_USER0);