[PATCH 5/6] hugetlb: make hugetlb_add_to_page_cache() use PAGE_SIZE-based index

[Jane Chu]

hugetlb_add_to_page_cache() currently takes a parameter named 'idx',
but internally converts it from hugetlb page units into PAGE_SIZE-based
page-cache index units before calling __filemap_add_folio().

Make hugetlb_add_to_page_cache() take a PAGE_SIZE-based index directly
and update its callers accordingly.  This removes the internal shift,
keeps the index units consistent with filemap_lock_folio() and
__filemap_add_folio(), and simplifies the surrounding code.

Signed-off-by: Jane Chu <jane.chu@xxxxxxxxxx>
---
 fs/hugetlbfs/inode.c    |  2 +-
 include/linux/hugetlb.h |  2 +-
 mm/hugetlb.c            | 21 ++++++++-------------
 mm/memfd.c              |  2 +-
 4 files changed, 11 insertions(+), 16 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index e24e9bf54e14..a72d46ff7980 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -825,7 +825,7 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
 		}
 		folio_zero_user(folio, addr);
 		__folio_mark_uptodate(folio);
-		error = hugetlb_add_to_page_cache(folio, mapping, idx);
+		error = hugetlb_add_to_page_cache(folio, mapping, index);
 		if (unlikely(error)) {
 			restore_reserve_on_error(h, &pseudo_vma, addr, folio);
 			folio_put(folio);
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 71691a2b6855..a51a5e12859c 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -713,7 +713,7 @@ struct folio *alloc_hugetlb_folio_reserve(struct hstate *h, int preferred_nid,
 					  nodemask_t *nmask, gfp_t gfp_mask);
 
 int hugetlb_add_to_page_cache(struct folio *folio, struct address_space *mapping,
-			pgoff_t idx);
+			pgoff_t index);
 void restore_reserve_on_error(struct hstate *h, struct vm_area_struct *vma,
 				unsigned long address, struct folio *folio);
 
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 138e5ecf818e..47ef41b6fb2e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5625,15 +5625,14 @@ bool hugetlbfs_pagecache_present(struct hstate *h,
 }
 
 int hugetlb_add_to_page_cache(struct folio *folio, struct address_space *mapping,
-			   pgoff_t idx)
+			   pgoff_t index)
 {
 	struct inode *inode = mapping->host;
 	struct hstate *h = hstate_inode(inode);
 	int err;
 
-	idx <<= huge_page_order(h);
 	__folio_set_locked(folio);
-	err = __filemap_add_folio(mapping, folio, idx, GFP_KERNEL, NULL);
+	err = __filemap_add_folio(mapping, folio, index, GFP_KERNEL, NULL);
 
 	if (unlikely(err)) {
 		__folio_clear_locked(folio);
@@ -5724,7 +5723,7 @@ static vm_fault_t hugetlb_no_page(struct address_space *mapping,
 	 * before we get page_table_lock.
 	 */
 	new_folio = false;
-	folio = filemap_lock_folio(mapping, vmf->pgoff << huge_page_order(h));
+	folio = filemap_lock_folio(mapping, index);
 	if (IS_ERR(folio)) {
 		size = i_size_read(mapping->host) >> huge_page_shift(h);
 		if (vmf->pgoff >= size)
@@ -5788,8 +5787,7 @@ static vm_fault_t hugetlb_no_page(struct address_space *mapping,
 		new_folio = true;
 
 		if (vma->vm_flags & VM_MAYSHARE) {
-			int err = hugetlb_add_to_page_cache(folio, mapping,
-							vmf->pgoff);
+			int err = hugetlb_add_to_page_cache(folio, mapping, index);
 			if (err) {
 				/*
 				 * err can't be -EEXIST which implies someone
@@ -6173,7 +6171,6 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte,
 			     uffd_flags_t flags,
 			     struct folio **foliop)
 {
-	pgoff_t idx;
 	spinlock_t *ptl;
 	struct folio *folio;
 	pte_t _dst_pte, dst_ptep;
@@ -6183,13 +6180,11 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte,
 	struct mm_struct *dst_mm = dst_vma->vm_mm;
 	bool wp_enabled = (flags & MFILL_ATOMIC_WP);
 	int vm_shared = dst_vma->vm_flags & VM_SHARED;
+	pgoff_t index = linear_page_index(dst_vma, dst_addr);
 	struct address_space *mapping = dst_vma->vm_file->f_mapping;
 	bool is_continue = uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE);
 	int ret = -ENOMEM;
 
-	idx = linear_page_index(dst_vma, dst_addr);
-	idx >>= huge_page_order(h);
-
 	if (uffd_flags_mode_is(flags, MFILL_ATOMIC_POISON)) {
 		ptl = huge_pte_lock(h, dst_mm, dst_pte);
 
@@ -6211,7 +6206,7 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte,
 
 	if (is_continue) {
 		ret = -EFAULT;
-		folio = filemap_lock_folio(mapping, idx << huge_page_order(h));
+		folio = filemap_lock_folio(mapping, index);
 		if (IS_ERR(folio))
 			goto out;
 		folio_in_pagecache = true;
@@ -6307,7 +6302,7 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte,
 	/* Add shared, newly allocated pages to the page cache. */
 	if (vm_shared && !is_continue) {
 		ret = -EFAULT;
-		if (idx >= (i_size_read(mapping->host) >> huge_page_shift(h)))
+		if (index >= (i_size_read(mapping->host) >> PAGE_SHIFT))
 			goto out_release_nounlock;
 
 		/*
@@ -6316,7 +6311,7 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte,
 		 * hugetlb_fault_mutex_table that here must be hold by
 		 * the caller.
 		 */
-		ret = hugetlb_add_to_page_cache(folio, mapping, idx);
+		ret = hugetlb_add_to_page_cache(folio, mapping, index);
 		if (ret)
 			goto out_release_nounlock;
 		folio_in_pagecache = true;
diff --git a/mm/memfd.c b/mm/memfd.c
index 911ff8220d05..56c8833c4195 100644
--- a/mm/memfd.c
+++ b/mm/memfd.c
@@ -122,7 +122,7 @@ struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t index)
 
 			err = hugetlb_add_to_page_cache(folio,
 							memfd->f_mapping,
-							idx);
+							index);
 
 			mutex_unlock(&hugetlb_fault_mutex_table[hash]);
 
-- 
2.43.5