huge page private reservation review cleanups
Andy Whitcroft [Thu, 24 Jul 2008 04:27:26 +0000 (21:27 -0700)]
Create some new accessors for vma private data to cut down on and contain
the casts.  Encapsulates the huge and small page offset calculations.
Also adds a couple of VM_BUG_ONs for consistency.

[akpm@linux-foundation.org: Make things static]
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Johannes Weiner <hannes@saeurebad.de>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb.c

index a2d29b8..3e873f0 100644 (file)
@@ -40,6 +40,28 @@ static int hugetlb_next_nid;
  */
 static DEFINE_SPINLOCK(hugetlb_lock);
 
+/*
+ * Convert the address within this vma to the page offset within
+ * the mapping, in base page units.
+ */
+static pgoff_t vma_page_offset(struct vm_area_struct *vma,
+                               unsigned long address)
+{
+       return ((address - vma->vm_start) >> PAGE_SHIFT) +
+                                       (vma->vm_pgoff >> PAGE_SHIFT);
+}
+
+/*
+ * Convert the address within this vma to the page offset within
+ * the mapping, in pagecache page units; huge pages here.
+ */
+static pgoff_t vma_pagecache_offset(struct vm_area_struct *vma,
+                                       unsigned long address)
+{
+       return ((address - vma->vm_start) >> HPAGE_SHIFT) +
+                       (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
+}
+
 #define HPAGE_RESV_OWNER    (1UL << (BITS_PER_LONG - 1))
 #define HPAGE_RESV_UNMAPPED (1UL << (BITS_PER_LONG - 2))
 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
@@ -53,36 +75,48 @@ static DEFINE_SPINLOCK(hugetlb_lock);
  * to reset the VMA at fork() time as it is not in use yet and there is no
  * chance of the global counters getting corrupted as a result of the values.
  */
+static unsigned long get_vma_private_data(struct vm_area_struct *vma)
+{
+       return (unsigned long)vma->vm_private_data;
+}
+
+static void set_vma_private_data(struct vm_area_struct *vma,
+                                                       unsigned long value)
+{
+       vma->vm_private_data = (void *)value;
+}
+
 static unsigned long vma_resv_huge_pages(struct vm_area_struct *vma)
 {
        VM_BUG_ON(!is_vm_hugetlb_page(vma));
        if (!(vma->vm_flags & VM_SHARED))
-               return (unsigned long)vma->vm_private_data & ~HPAGE_RESV_MASK;
+               return get_vma_private_data(vma) & ~HPAGE_RESV_MASK;
        return 0;
 }
 
 static void set_vma_resv_huge_pages(struct vm_area_struct *vma,
                                                        unsigned long reserve)
 {
-       unsigned long flags;
        VM_BUG_ON(!is_vm_hugetlb_page(vma));
        VM_BUG_ON(vma->vm_flags & VM_SHARED);
 
-       flags = (unsigned long)vma->vm_private_data & HPAGE_RESV_MASK;
-       vma->vm_private_data = (void *)(reserve | flags);
+       set_vma_private_data(vma,
+               (get_vma_private_data(vma) & HPAGE_RESV_MASK) | reserve);
 }
 
 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
 {
-       unsigned long reserveflags = (unsigned long)vma->vm_private_data;
        VM_BUG_ON(!is_vm_hugetlb_page(vma));
-       vma->vm_private_data = (void *)(reserveflags | flags);
+       VM_BUG_ON(vma->vm_flags & VM_SHARED);
+
+       set_vma_private_data(vma, get_vma_private_data(vma) | flags);
 }
 
 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
 {
        VM_BUG_ON(!is_vm_hugetlb_page(vma));
-       return ((unsigned long)vma->vm_private_data & flag) != 0;
+
+       return (get_vma_private_data(vma) & flag) != 0;
 }
 
 /* Decrement the reserved pages in the hugepage pool by one */
@@ -1151,11 +1185,10 @@ static struct page *hugetlbfs_pagecache_page(struct vm_area_struct *vma,
                        unsigned long address)
 {
        struct address_space *mapping;
-       unsigned long idx;
+       pgoff_t idx;
 
        mapping = vma->vm_file->f_mapping;
-       idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
-               + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
+       idx = vma_pagecache_offset(vma, address);
 
        return find_lock_page(mapping, idx);
 }
@@ -1164,7 +1197,7 @@ static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
                        unsigned long address, pte_t *ptep, int write_access)
 {
        int ret = VM_FAULT_SIGBUS;
-       unsigned long idx;
+       pgoff_t idx;
        unsigned long size;
        struct page *page;
        struct address_space *mapping;
@@ -1183,8 +1216,7 @@ static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
        }
 
        mapping = vma->vm_file->f_mapping;
-       idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
-               + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
+       idx = vma_pagecache_offset(vma, address);
 
        /*
         * Use page lock to guard against racing truncation