[PATCH v7 70/70] mm/mmap.c: Pass in mapping to __vma_link_file()

Liam Howlett
2022-04-04T14:44:32Z

__vma_link_file() resolves the mapping from the file, if there is one.
Pass through the mapping and check the vm_file externally since most
places already have the required information and check of vm_file.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
mm/mmap.c | 42 ++++++++++++++++++++----------------------
1 file changed, 20 insertions(+), 22 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 119251fa2d53..7365e32f1f03 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -449,21 +449,15 @@ static unsigned long count_vma_pages_range(struct mm_struct *mm,
return nr_pages;
}

-static void __vma_link_file(struct vm_area_struct *vma)
+static void __vma_link_file(struct vm_area_struct *vma,
+ struct address_space *mapping)
{
- struct file *file;
-
- file = vma->vm_file;
- if (file) {
- struct address_space *mapping = file->f_mapping;
-
- if (vma->vm_flags & VM_SHARED)
- mapping_allow_writable(mapping);
+ if (vma->vm_flags & VM_SHARED)
+ mapping_allow_writable(mapping);

- flush_dcache_mmap_lock(mapping);
- vma_interval_tree_insert(vma, &mapping->i_mmap);
- flush_dcache_mmap_unlock(mapping);
- }
+ flush_dcache_mmap_lock(mapping);
+ vma_interval_tree_insert(vma, &mapping->i_mmap);
+ flush_dcache_mmap_unlock(mapping);
}

/*
@@ -506,10 +500,11 @@ static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma)
}

vma_store(mm, vma);
- __vma_link_file(vma);

- if (mapping)
+ if (mapping) {
+ __vma_link_file(vma, mapping);
i_mmap_unlock_write(mapping);
+ }

mm->map_count++;
validate_mm(mm);
@@ -742,14 +737,14 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
uprobe_munmap(next, next->vm_start, next->vm_end);

i_mmap_lock_write(mapping);
- if (insert) {
+ if (insert && insert->vm_file) {
/*
* Put into interval tree now, so instantiated pages
* are visible to arm/parisc __flush_dcache_page
* throughout; but we cannot insert into address
* space until vma start or end is updated.
*/
- __vma_link_file(insert);
+ __vma_link_file(insert, insert->vm_file->f_mapping);
}
}

@@ -2958,6 +2953,7 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
unsigned long addr, unsigned long len, unsigned long flags)
{
+ struct address_space *mapping = NULL;
struct mm_struct *mm = current->mm;
validate_mm_mt(mm);

@@ -3013,13 +3009,15 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
vma->vm_pgoff = addr >> PAGE_SHIFT;
vma->vm_flags = flags;
vma->vm_page_prot = vm_get_page_prot(flags);
- if (vma->vm_file)
- i_mmap_lock_write(vma->vm_file->f_mapping);
+ if (vma->vm_file) {
+ mapping = vma->vm_file->f_mapping;
+ i_mmap_lock_write(mapping);
+ }
vma_mas_store(vma, mas);
mm->map_count++;
- if (vma->vm_file) {
- __vma_link_file(vma);
- i_mmap_unlock_write(vma->vm_file->f_mapping);
+ if (mapping) {
+ __vma_link_file(vma, mapping);
+ i_mmap_unlock_write(mapping);
}

out:
--
2.34.1