[PATCH v10 69/69] mm/mmap.c: pass in mapping to __vma_link_file()

[Liam Howlett <liam.howlett@oracle.com>]

From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>

__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.

Link: https://lkml.kernel.org/r/20220504011345.662299-54-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/mmap.c | 33 ++++++++++++++-------------------
 1 file changed, 14 insertions(+), 19 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 2a73467670e7..52192408e6a5 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -246,6 +246,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 	if (brk < min_brk)
 		goto out;
 
+
 	/*
 	 * Check against rlimit here. If this check is done later after the test
 	 * of oldbrk with newbrk then it can escape the test and let the data
@@ -322,7 +323,6 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 	if (populate)
 		mm_populate(oldbrk, newbrk - oldbrk);
 	return brk;
-
 out:
 	mmap_write_unlock(mm);
 	return origbrk;
@@ -454,21 +454,15 @@ 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);
 }
 
 /*
@@ -535,10 +529,11 @@ static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma)
 	}
 
 	vma_mas_store(vma, &mas);
-	__vma_link_file(vma);
 
-	if (mapping)
+	if (mapping) {
+		__vma_link_file(vma, mapping);
 		i_mmap_unlock_write(mapping);
+	}
 
 	mm->map_count++;
 	validate_mm(mm);
@@ -782,14 +777,14 @@ 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);
 		}
 	}
 
@@ -3054,7 +3049,6 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
 	struct mm_struct *mm = current->mm;
 	validate_mm_mt(mm);
 
-
 	/*
 	 * Check against address space limits by the changed size
 	 * Note: This happens *after* clearing old mappings in some code paths.
@@ -3112,6 +3106,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
 		goto mas_store_fail;
 
 	mm->map_count++;
+
 out:
 	perf_event_mmap(vma);
 	mm->total_vm += len >> PAGE_SHIFT;
-- 
2.35.1