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Subject[PATCH 3/19] do_mremap() untangling, part 3
From

Take the check for being able to expand vma in place into a separate
helper.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
mm/mremap.c | 16 ++++++++++++----
1 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/mm/mremap.c b/mm/mremap.c
index 5f34617..90e422c 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -366,6 +366,17 @@ out:
return ret;
}

+static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
+{
+ unsigned long max_addr = TASK_SIZE;
+ if (vma->vm_next)
+ max_addr = vma->vm_next->vm_start;
+ if (max_addr - vma->vm_end < delta)
+ return 0;
+ /* we need to do arch-specific checks here */
+ return 1;
+}
+
/*
* Expand (or shrink) an existing mapping, potentially moving it at the
* same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
@@ -430,11 +441,8 @@ unsigned long do_mremap(unsigned long addr,
/* old_len exactly to the end of the area..
*/
if (old_len == vma->vm_end - addr) {
- unsigned long max_addr = TASK_SIZE;
- if (vma->vm_next)
- max_addr = vma->vm_next->vm_start;
/* can we just expand the current mapping? */
- if (max_addr - addr >= new_len) {
+ if (vma_expandable(vma, new_len - old_len)) {
int pages = (new_len - old_len) >> PAGE_SHIFT;

vma_adjust(vma, vma->vm_start,
--
1.5.6.5



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