mm: shmem: move shmem_huge_global_enabled() into shmem_allowable_huge_orders()

Move shmem_huge_global_enabled() into shmem_allowable_huge_orders(), so
that shmem_allowable_huge_orders() can also help to find the allowable
huge orders for tmpfs.  Moreover the shmem_huge_global_enabled() can
become static.  While we are at it, passing the vma instead of mm for
shmem_huge_global_enabled() makes code cleaner.

No functional changes.

Link: https://lkml.kernel.org/r/8e825146bb29ee1a1c7bd64d2968ff3e19be7815.1721626645.git.baolin.wang@linux.alibaba.comSigned-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/shmem_fs.h

@@ -111,21 +111,13 @@ extern void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);
 int shmem_unuse(unsigned int type);
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-extern bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index, bool shmem_huge_force,
-				      struct mm_struct *mm, unsigned long vm_flags);
 unsigned long shmem_allowable_huge_orders(struct inode *inode,
 				struct vm_area_struct *vma, pgoff_t index,
-				bool global_huge);
+				bool shmem_huge_force);
 #else
-static __always_inline bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
-						      bool shmem_huge_force, struct mm_struct *mm,
-						      unsigned long vm_flags)
-{
-	return false;
-}
 static inline unsigned long shmem_allowable_huge_orders(struct inode *inode,
 				struct vm_area_struct *vma, pgoff_t index,
-				bool global_huge)
+				bool shmem_huge_force)
 {
 	return 0;
 }

mm/huge_memory.c

@@ -159,16 +159,10 @@ unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
 	 * Must be done before hugepage flags check since shmem has its
 	 * own flags.
 	 */
-	if (!in_pf && shmem_file(vma->vm_file)) {
-		bool global_huge = shmem_huge_global_enabled(file_inode(vma->vm_file),
-							     vma->vm_pgoff, !enforce_sysfs,
-							     vma->vm_mm, vm_flags);
-
-		if (!vma_is_anon_shmem(vma))
-			return global_huge ? orders : 0;
+	if (!in_pf && shmem_file(vma->vm_file))
 		return shmem_allowable_huge_orders(file_inode(vma->vm_file),
-							vma, vma->vm_pgoff, global_huge);
-	}
+						   vma, vma->vm_pgoff,
+						   !enforce_sysfs);
 
 	if (!vma_is_anonymous(vma)) {
 		/*

mm/shmem.c

@@ -549,9 +549,10 @@ static bool shmem_confirm_swap(struct address_space *mapping,
 static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER;
 
 static bool __shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
-					bool shmem_huge_force, struct mm_struct *mm,
+					bool shmem_huge_force, struct vm_area_struct *vma,
 					unsigned long vm_flags)
 {
+	struct mm_struct *mm = vma ? vma->vm_mm : NULL;
 	loff_t i_size;
 
 	if (!S_ISREG(inode->i_mode))
@@ -581,15 +582,15 @@ static bool __shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
 	}
 }
 
-bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
-		   bool shmem_huge_force, struct mm_struct *mm,
+static bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
+		   bool shmem_huge_force, struct vm_area_struct *vma,
 		   unsigned long vm_flags)
 {
 	if (HPAGE_PMD_ORDER > MAX_PAGECACHE_ORDER)
 		return false;
 
 	return __shmem_huge_global_enabled(inode, index, shmem_huge_force,
-					   mm, vm_flags);
+					   vma, vm_flags);
 }
 
 #if defined(CONFIG_SYSFS)
@@ -772,6 +773,13 @@ static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
 {
 	return 0;
 }
+
+static bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
+		bool shmem_huge_force, struct vm_area_struct *vma,
+		unsigned long vm_flags)
+{
+	return false;
+}
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 /*
@@ -1625,22 +1633,33 @@ static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 unsigned long shmem_allowable_huge_orders(struct inode *inode,
 				struct vm_area_struct *vma, pgoff_t index,
-				bool global_huge)
+				bool shmem_huge_force)
 {
 	unsigned long mask = READ_ONCE(huge_shmem_orders_always);
 	unsigned long within_size_orders = READ_ONCE(huge_shmem_orders_within_size);
-	unsigned long vm_flags = vma->vm_flags;
+	unsigned long vm_flags = vma ? vma->vm_flags : 0;
+	bool global_huge;
 	loff_t i_size;
 	int order;
 
-	if ((vm_flags & VM_NOHUGEPAGE) ||
-	    test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
+	if (vma && ((vm_flags & VM_NOHUGEPAGE) ||
+	    test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)))
 		return 0;
 
 	/* If the hardware/firmware marked hugepage support disabled. */
 	if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED))
 		return 0;
 
+	global_huge = shmem_huge_global_enabled(inode, index, shmem_huge_force,
+						vma, vm_flags);
+	if (!vma || !vma_is_anon_shmem(vma)) {
+		/*
+		 * For tmpfs, we now only support PMD sized THP if huge page
+		 * is enabled, otherwise fallback to order 0.
+		 */
+		return global_huge ? BIT(HPAGE_PMD_ORDER) : 0;
+	}
+
 	/*
 	 * Following the 'deny' semantics of the top level, force the huge
 	 * option off from all mounts.
@@ -2077,7 +2096,7 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
 	struct mm_struct *fault_mm;
 	struct folio *folio;
 	int error;
-	bool alloced, huge;
+	bool alloced;
 	unsigned long orders = 0;
 
 	if (WARN_ON_ONCE(!shmem_mapping(inode->i_mapping)))
@@ -2150,14 +2169,8 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
 		return 0;
 	}
 
-	huge = shmem_huge_global_enabled(inode, index, false, fault_mm,
-			     vma ? vma->vm_flags : 0);
-	/* Find hugepage orders that are allowed for anonymous shmem. */
-	if (vma && vma_is_anon_shmem(vma))
-		orders = shmem_allowable_huge_orders(inode, vma, index, huge);
-	else if (huge)
-		orders = BIT(HPAGE_PMD_ORDER);
-
+	/* Find hugepage orders that are allowed for anonymous shmem and tmpfs. */
+	orders = shmem_allowable_huge_orders(inode, vma, index, false);
 	if (orders > 0) {
 		gfp_t huge_gfp;