Remove internal use of 'write_access' in mm/memory.c
Linus Torvalds [Fri, 10 Apr 2009 15:43:11 +0000 (08:43 -0700)]
The fault handling routines really want more fine-grained flags than a
single "was it a write fault" boolean - the callers will want to set
flags like "you can return a retry error" etc.

And that's actually how the VM works internally, but right now the
top-level fault handling functions in mm/memory.c all pass just the
'write_access' boolean around.

This switches them over to pass around the FAULT_FLAG_xyzzy 'flags'
variable instead.  The 'write_access' calling convention still exists
for the exported 'handle_mm_fault()' function, but that is next.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory.c

index d5d1653..e6a9700 100644 (file)
@@ -2496,7 +2496,7 @@ int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
  */
 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
                unsigned long address, pte_t *page_table, pmd_t *pmd,
-               int write_access, pte_t orig_pte)
+               unsigned int flags, pte_t orig_pte)
 {
        spinlock_t *ptl;
        struct page *page;
@@ -2572,9 +2572,9 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
 
        inc_mm_counter(mm, anon_rss);
        pte = mk_pte(page, vma->vm_page_prot);
-       if (write_access && reuse_swap_page(page)) {
+       if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
                pte = maybe_mkwrite(pte_mkdirty(pte), vma);
-               write_access = 0;
+               flags &= ~FAULT_FLAG_WRITE;
        }
        flush_icache_page(vma, page);
        set_pte_at(mm, address, page_table, pte);
@@ -2587,7 +2587,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
                try_to_free_swap(page);
        unlock_page(page);
 
-       if (write_access) {
+       if (flags & FAULT_FLAG_WRITE) {
                ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
                if (ret & VM_FAULT_ERROR)
                        ret &= VM_FAULT_ERROR;
@@ -2616,7 +2616,7 @@ out_page:
  */
 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
                unsigned long address, pte_t *page_table, pmd_t *pmd,
-               int write_access)
+               unsigned int flags)
 {
        struct page *page;
        spinlock_t *ptl;
@@ -2776,7 +2776,7 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
         * due to the bad i386 page protection. But it's valid
         * for other architectures too.
         *
-        * Note that if write_access is true, we either now have
+        * Note that if FAULT_FLAG_WRITE is set, we either now have
         * an exclusive copy of the page, or this is a shared mapping,
         * so we can make it writable and dirty to avoid having to
         * handle that later.
@@ -2847,11 +2847,10 @@ unwritable_page:
 
 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
                unsigned long address, pte_t *page_table, pmd_t *pmd,
-               int write_access, pte_t orig_pte)
+               unsigned int flags, pte_t orig_pte)
 {
        pgoff_t pgoff = (((address & PAGE_MASK)
                        - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
-       unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);
 
        pte_unmap(page_table);
        return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
@@ -2868,12 +2867,12 @@ static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
  */
 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
                unsigned long address, pte_t *page_table, pmd_t *pmd,
-               int write_access, pte_t orig_pte)
+               unsigned int flags, pte_t orig_pte)
 {
-       unsigned int flags = FAULT_FLAG_NONLINEAR |
-                               (write_access ? FAULT_FLAG_WRITE : 0);
        pgoff_t pgoff;
 
+       flags |= FAULT_FLAG_NONLINEAR;
+
        if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
                return 0;
 
@@ -2904,7 +2903,7 @@ static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
  */
 static inline int handle_pte_fault(struct mm_struct *mm,
                struct vm_area_struct *vma, unsigned long address,
-               pte_t *pte, pmd_t *pmd, int write_access)
+               pte_t *pte, pmd_t *pmd, unsigned int flags)
 {
        pte_t entry;
        spinlock_t *ptl;
@@ -2915,30 +2914,30 @@ static inline int handle_pte_fault(struct mm_struct *mm,
                        if (vma->vm_ops) {
                                if (likely(vma->vm_ops->fault))
                                        return do_linear_fault(mm, vma, address,
-                                               pte, pmd, write_access, entry);
+                                               pte, pmd, flags, entry);
                        }
                        return do_anonymous_page(mm, vma, address,
-                                                pte, pmd, write_access);
+                                                pte, pmd, flags);
                }
                if (pte_file(entry))
                        return do_nonlinear_fault(mm, vma, address,
-                                       pte, pmd, write_access, entry);
+                                       pte, pmd, flags, entry);
                return do_swap_page(mm, vma, address,
-                                       pte, pmd, write_access, entry);
+                                       pte, pmd, flags, entry);
        }
 
        ptl = pte_lockptr(mm, pmd);
        spin_lock(ptl);
        if (unlikely(!pte_same(*pte, entry)))
                goto unlock;
-       if (write_access) {
+       if (flags & FAULT_FLAG_WRITE) {
                if (!pte_write(entry))
                        return do_wp_page(mm, vma, address,
                                        pte, pmd, ptl, entry);
                entry = pte_mkdirty(entry);
        }
        entry = pte_mkyoung(entry);
-       if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
+       if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
                update_mmu_cache(vma, address, entry);
        } else {
                /*
@@ -2947,7 +2946,7 @@ static inline int handle_pte_fault(struct mm_struct *mm,
                 * This still avoids useless tlb flushes for .text page faults
                 * with threads.
                 */
-               if (write_access)
+               if (flags & FAULT_FLAG_WRITE)
                        flush_tlb_page(vma, address);
        }
 unlock:
@@ -2965,13 +2964,14 @@ int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;
+       unsigned int flags = write_access ? FAULT_FLAG_WRITE : 0;
 
        __set_current_state(TASK_RUNNING);
 
        count_vm_event(PGFAULT);
 
        if (unlikely(is_vm_hugetlb_page(vma)))
-               return hugetlb_fault(mm, vma, address, write_access);
+               return hugetlb_fault(mm, vma, address, flags);
 
        pgd = pgd_offset(mm, address);
        pud = pud_alloc(mm, pgd, address);
@@ -2984,7 +2984,7 @@ int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
        if (!pte)
                return VM_FAULT_OOM;
 
-       return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
+       return handle_pte_fault(mm, vma, address, pte, pmd, flags);
 }
 
 #ifndef __PAGETABLE_PUD_FOLDED