btrfs: prepare btrfs_page_mkwrite() for large folios

This changes the assumption that the folio is always page sized.
(Although the ASSERT() for folio order is still kept as-is).

Just replace the PAGE_SIZE with folio_size().

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: adam900710

fs/btrfs/file.c

@@ -1782,6 +1782,7 @@ static vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf)
 	struct extent_changeset *data_reserved = NULL;
 	unsigned long zero_start;
 	loff_t size;
+	size_t fsize = folio_size(folio);
 	vm_fault_t ret;
 	int ret2;
 	int reserved = 0;
@@ -1792,7 +1793,7 @@ static vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf)
 
 	ASSERT(folio_order(folio) == 0);
 
-	reserved_space = PAGE_SIZE;
+	reserved_space = fsize;
 
 	sb_start_pagefault(inode->i_sb);
 	page_start = folio_pos(folio);
@@ -1846,7 +1847,7 @@ static vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf)
 	 * We can't set the delalloc bits if there are pending ordered
 	 * extents.  Drop our locks and wait for them to finish.
 	 */
-	ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), page_start, PAGE_SIZE);
+	ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), page_start, fsize);
 	if (ordered) {
 		unlock_extent(io_tree, page_start, page_end, &cached_state);
 		folio_unlock(folio);
@@ -1858,11 +1859,11 @@ static vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf)
 
 	if (folio->index == ((size - 1) >> PAGE_SHIFT)) {
 		reserved_space = round_up(size - page_start, fs_info->sectorsize);
-		if (reserved_space < PAGE_SIZE) {
+		if (reserved_space < fsize) {
 			end = page_start + reserved_space - 1;
 			btrfs_delalloc_release_space(BTRFS_I(inode),
 					data_reserved, page_start,
-					PAGE_SIZE - reserved_space, true);
+					fsize - reserved_space, true);
 		}
 	}
 
@@ -1889,12 +1890,12 @@ static vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf)
 	if (page_start + folio_size(folio) > size)
 		zero_start = offset_in_folio(folio, size);
 	else
-		zero_start = PAGE_SIZE;
+		zero_start = fsize;
 
-	if (zero_start != PAGE_SIZE)
+	if (zero_start != fsize)
 		folio_zero_range(folio, zero_start, folio_size(folio) - zero_start);
 
-	btrfs_folio_clear_checked(fs_info, folio, page_start, PAGE_SIZE);
+	btrfs_folio_clear_checked(fs_info, folio, page_start, fsize);
 	btrfs_folio_set_dirty(fs_info, folio, page_start, end + 1 - page_start);
 	btrfs_folio_set_uptodate(fs_info, folio, page_start, end + 1 - page_start);
 
@@ -1903,7 +1904,7 @@ static vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf)
 	unlock_extent(io_tree, page_start, page_end, &cached_state);
 	up_read(&BTRFS_I(inode)->i_mmap_lock);
 
-	btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
+	btrfs_delalloc_release_extents(BTRFS_I(inode), fsize);
 	sb_end_pagefault(inode->i_sb);
 	extent_changeset_free(data_reserved);
 	return VM_FAULT_LOCKED;
@@ -1912,7 +1913,7 @@ static vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf)
 	folio_unlock(folio);
 	up_read(&BTRFS_I(inode)->i_mmap_lock);
 out:
-	btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
+	btrfs_delalloc_release_extents(BTRFS_I(inode), fsize);
 	btrfs_delalloc_release_space(BTRFS_I(inode), data_reserved, page_start,
 				     reserved_space, (ret != 0));
 out_noreserve: