mm/vma: use guard clauses in can_vma_merge_[before, after]()

Rather than combining a bunch of conditionals in a single expression,
simplify by inverting the mergeability requirements into guard clauses.

that is - instead of checking what must be true for the conditions to be
met, instead check the inverse of the requirements and return false if any
are true, defaulting to true.

No functional change intended.

Link: https://lore.kernel.org/20260710-b4-pre-scalable-cow-v2-31-2a5aa403d977@kernel.org
Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Ackerley Tng <ackerleytng@google.com>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Kai Huang <kai.huang@intel.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: SJ Park <sj@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Liam R. Howlett (Oracle) <liam@infradead.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 14 insertions, 13 deletions

diff --git a/mm/vma.c b/mm/vma.c
index d74a8ae16bfa..12a684c36b6c 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -215,13 +215,13 @@ static void init_multi_vma_prep(struct vma_prepare *vp,
  */
 static bool can_vma_merge_before(struct vma_merge_struct *vmg)
 {
-	if (is_mergeable_vma(vmg, /* merge_next = */ true) &&
-	    is_mergeable_anon_vma(vmg, /* merge_next = */ true)) {
-		if (vmg_end_pgoff(vmg) == vma_start_pgoff(vmg->next))
-			return true;
-	}
-
-	return false;
+	if (!is_mergeable_vma(vmg, /* merge_next = */ true))
+		return false;
+	if (!is_mergeable_anon_vma(vmg, /* merge_next = */ true))
+		return false;
+	if (vmg_end_pgoff(vmg) != vma_start_pgoff(vmg->next))
+		return false;
+	return true;
 }
 
 /*
@@ -235,12 +235,13 @@ static bool can_vma_merge_before(struct vma_merge_struct *vmg)
  */
 static bool can_vma_merge_after(struct vma_merge_struct *vmg)
 {
-	if (is_mergeable_vma(vmg, /* merge_next = */ false) &&
-	    is_mergeable_anon_vma(vmg, /* merge_next = */ false)) {
-		if (vma_end_pgoff(vmg->prev) == vmg_start_pgoff(vmg))
-			return true;
-	}
-	return false;
+	if (!is_mergeable_vma(vmg, /* merge_next = */ false))
+		return false;
+	if (!is_mergeable_anon_vma(vmg, /* merge_next = */ false))
+		return false;
+	if (vma_end_pgoff(vmg->prev) != vmg_start_pgoff(vmg))
+		return false;
+	return true;
 }
 
 static void __vma_link_file(struct vm_area_struct *vma,