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ksm: first tidy up madvise_vma() 

madvise.c has several levels of switch statements, what to do in which?
Move MADV_DOFORK code down from madvise_vma() to madvise_behavior(), so
madvise_vma() can be a simple router, to madvise_behavior() by default.

vma->vm_flags is an unsigned long so use the same type for new_flags.  Add
missing comment lines to describe MADV_DONTFORK and MADV_DOFORK.

Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Chris Wright <chrisw@redhat.com>
Signed-off-by: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2009-09-21 17:01:52 -07:00 committed by Linus Torvalds
parent 828502d300
commit 3866ea90d3
1 changed files with 13 additions and 26 deletions
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39
mm/madvise.c
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@ -41,7 +41,7 @@ static long madvise_behavior(struct vm_area_struct * vma,
struct mm_struct * mm = vma->vm_mm;
int error = 0;
pgoff_t pgoff;
int new_flags = vma->vm_flags;
unsigned long new_flags = vma->vm_flags;
switch (behavior) {
case MADV_NORMAL:
@ -57,6 +57,10 @@ static long madvise_behavior(struct vm_area_struct * vma,
new_flags |= VM_DONTCOPY;
break;
case MADV_DOFORK:
if (vma->vm_flags & VM_IO) {
error = -EINVAL;
goto out;
}
new_flags &= ~VM_DONTCOPY;
break;
}
@ -211,37 +215,16 @@ static long
madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
unsigned long start, unsigned long end, int behavior)
{
long error;
switch (behavior) {
case MADV_DOFORK:
if (vma->vm_flags & VM_IO) {
error = -EINVAL;
break;
}
case MADV_DONTFORK:
case MADV_NORMAL:
case MADV_SEQUENTIAL:
case MADV_RANDOM:
error = madvise_behavior(vma, prev, start, end, behavior);
break;
case MADV_REMOVE:
error = madvise_remove(vma, prev, start, end);
break;
return madvise_remove(vma, prev, start, end);
case MADV_WILLNEED:
error = madvise_willneed(vma, prev, start, end);
break;
return madvise_willneed(vma, prev, start, end);
case MADV_DONTNEED:
error = madvise_dontneed(vma, prev, start, end);
break;
return madvise_dontneed(vma, prev, start, end);
default:
BUG();
break;
return madvise_behavior(vma, prev, start, end, behavior);
}
return error;
}
static int
@ -262,6 +245,7 @@ madvise_behavior_valid(int behavior)
return 0;
}
}
/*
* The madvise(2) system call.
*
@ -286,6 +270,9 @@ madvise_behavior_valid(int behavior)
* so the kernel can free resources associated with it.
* MADV_REMOVE - the application wants to free up the given range of
* pages and associated backing store.
* MADV_DONTFORK - omit this area from child's address space when forking:
* typically, to avoid COWing pages pinned by get_user_pages().
* MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
*
* return values:
* zero - success