[v3 PATCH 4/8] mm: thp: only regular file could be THP eligible

[Yang Shi <shy828301@xxxxxxxxx>]

Since commit a4aeaa06d45e ("mm: khugepaged: skip huge page collapse for
special files"), khugepaged just collapses THP for regular file which is
the intended usecase for readonly fs THP.  Only show regular file as THP
eligible accordingly.

And make file_thp_enabled() available for khugepaged too in order to remove
duplicate code.

Acked-by: Song Liu <song@xxxxxxxxxx>
Signed-off-by: Yang Shi <shy828301@xxxxxxxxx>
---
 include/linux/huge_mm.h | 14 ++++++++++++++
 mm/huge_memory.c        | 11 ++---------
 mm/khugepaged.c         |  9 ++-------
 3 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 2999190adc22..62a6f667850d 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -172,6 +172,20 @@ static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
 	return false;
 }
 
+static inline bool file_thp_enabled(struct vm_area_struct *vma)
+{
+	struct inode *inode;
+
+	if (!vma->vm_file)
+		return false;
+
+	inode = vma->vm_file->f_inode;
+
+	return (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) &&
+	       (vma->vm_flags & VM_EXEC) &&
+	       !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode);
+}
+
 bool transparent_hugepage_active(struct vm_area_struct *vma);
 
 #define transparent_hugepage_use_zero_page()				\
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2fe38212e07c..183b793fd28e 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -68,13 +68,6 @@ static atomic_t huge_zero_refcount;
 struct page *huge_zero_page __read_mostly;
 unsigned long huge_zero_pfn __read_mostly = ~0UL;
 
-static inline bool file_thp_enabled(struct vm_area_struct *vma)
-{
-	return transhuge_vma_enabled(vma, vma->vm_flags) && vma->vm_file &&
-	       !inode_is_open_for_write(vma->vm_file->f_inode) &&
-	       (vma->vm_flags & VM_EXEC);
-}
-
 bool transparent_hugepage_active(struct vm_area_struct *vma)
 {
 	/* The addr is used to check if the vma size fits */
@@ -86,8 +79,8 @@ bool transparent_hugepage_active(struct vm_area_struct *vma)
 		return __transparent_hugepage_enabled(vma);
 	if (vma_is_shmem(vma))
 		return shmem_huge_enabled(vma);
-	if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS))
-		return file_thp_enabled(vma);
+	if (transhuge_vma_enabled(vma, vma->vm_flags) && file_thp_enabled(vma))
+		return true;
 
 	return false;
 }
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 964a4d2c942a..609c1bc0a027 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -464,13 +464,8 @@ static bool hugepage_vma_check(struct vm_area_struct *vma,
 		return false;
 
 	/* Only regular file is valid */
-	if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && vma->vm_file &&
-	    (vm_flags & VM_EXEC)) {
-		struct inode *inode = vma->vm_file->f_inode;
-
-		return !inode_is_open_for_write(inode) &&
-			S_ISREG(inode->i_mode);
-	}
+	if (file_thp_enabled(vma))
+		return true;
 
 	if (!vma->anon_vma || vma->vm_ops)
 		return false;
-- 
2.26.3