untangling do_mremap(), part 1

Take locating vma and checks on it to a separate helper (it will be
shared between MREMAP_FIXED/non-MREMAP_FIXED cases when we split
them in the next patch)

Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/mm/mremap.c b/mm/mremap.c
index 97bff2547719e702150e1cdc4d4a3f6b31a23213..67761361c4690bf5d2f8a769557be4862a60bf28 100644 (file)
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -261,6 +261,58 @@ static unsigned long move_vma(struct vm_area_struct *vma,
        return new_addr;
 }
 
+static struct vm_area_struct *vma_to_resize(unsigned long addr,
+       unsigned long old_len, unsigned long new_len, unsigned long *p)
+{
+       struct mm_struct *mm = current->mm;
+       struct vm_area_struct *vma = find_vma(mm, addr);
+
+       if (!vma || vma->vm_start > addr)
+               goto Efault;
+
+       if (is_vm_hugetlb_page(vma))
+               goto Einval;
+
+       /* We can't remap across vm area boundaries */
+       if (old_len > vma->vm_end - addr)
+               goto Efault;
+
+       if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {
+               if (new_len > old_len)
+                       goto Efault;
+       }
+
+       if (vma->vm_flags & VM_LOCKED) {
+               unsigned long locked, lock_limit;
+               locked = mm->locked_vm << PAGE_SHIFT;
+               lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
+               locked += new_len - old_len;
+               if (locked > lock_limit && !capable(CAP_IPC_LOCK))
+                       goto Eagain;
+       }
+
+       if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
+               goto Enomem;
+
+       if (vma->vm_flags & VM_ACCOUNT) {
+               unsigned long charged = (new_len - old_len) >> PAGE_SHIFT;
+               if (security_vm_enough_memory(charged))
+                       goto Efault;
+               *p = charged;
+       }
+
+       return vma;
+
+Efault:        /* very odd choice for most of the cases, but... */
+       return ERR_PTR(-EFAULT);
+Einval:
+       return ERR_PTR(-EINVAL);
+Enomem:
+       return ERR_PTR(-ENOMEM);
+Eagain:
+       return ERR_PTR(-EAGAIN);
+}
+
 /*
  * Expand (or shrink) an existing mapping, potentially moving it at the
  * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
@@ -340,41 +392,12 @@ unsigned long do_mremap(unsigned long addr,
        /*
         * Ok, we need to grow..  or relocate.
         */
-       ret = -EFAULT;
-       vma = find_vma(mm, addr);
-       if (!vma || vma->vm_start > addr)
-               goto out;
-       if (is_vm_hugetlb_page(vma)) {
-               ret = -EINVAL;
-               goto out;
-       }
-       /* We can't remap across vm area boundaries */
-       if (old_len > vma->vm_end - addr)
-               goto out;
-       if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {
-               if (new_len > old_len)
-                       goto out;
-       }
-       if (vma->vm_flags & VM_LOCKED) {
-               unsigned long locked, lock_limit;
-               locked = mm->locked_vm << PAGE_SHIFT;
-               lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
-               locked += new_len - old_len;
-               ret = -EAGAIN;
-               if (locked > lock_limit && !capable(CAP_IPC_LOCK))
-                       goto out;
-       }
-       if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) {
-               ret = -ENOMEM;
+       vma = vma_to_resize(addr, old_len, new_len, &charged);
+       if (IS_ERR(vma)) {
+               ret = PTR_ERR(vma);
                goto out;
        }
 
-       if (vma->vm_flags & VM_ACCOUNT) {
-               charged = (new_len - old_len) >> PAGE_SHIFT;
-               if (security_vm_enough_memory(charged))
-                       goto out_nc;
-       }
-
        /* old_len exactly to the end of the area..
         * And we're not relocating the area.
         */
@@ -430,7 +453,6 @@ unsigned long do_mremap(unsigned long addr,
 out:
        if (ret & ~PAGE_MASK)
                vm_unacct_memory(charged);
-out_nc:
        return ret;
 }