nilfs2: convert common metadata file code to be folio-based

In the common routines for metadata files, nilfs_mdt_insert_new_block(),
which inserts a new block buffer into the cache, is still page-based, and
there are two places where bh_offset() is used.  Convert these to
page-based.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ryusuke Konishi <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: konis

fs/nilfs2/alloc.c

@@ -177,12 +177,14 @@ nilfs_palloc_entry_blkoff(const struct inode *inode, __u64 nr)
  * nilfs_palloc_desc_block_init - initialize buffer of a group descriptor block
  * @inode: inode of metadata file
  * @bh: buffer head of the buffer to be initialized
- * @kaddr: kernel address mapped for the page including the buffer
+ * @from: kernel address mapped for a chunk of the block
+ *
+ * This function does not yet support the case where block size > PAGE_SIZE.
  */
 static void nilfs_palloc_desc_block_init(struct inode *inode,
-					 struct buffer_head *bh, void *kaddr)
+					 struct buffer_head *bh, void *from)
 {
-	struct nilfs_palloc_group_desc *desc = kaddr + bh_offset(bh);
+	struct nilfs_palloc_group_desc *desc = from;
 	unsigned long n = nilfs_palloc_groups_per_desc_block(inode);
 	__le32 nfrees;
 

fs/nilfs2/cpfile.c

@@ -113,9 +113,9 @@ nilfs_cpfile_block_get_checkpoint(const struct inode *cpfile, __u64 cno,
 
 static void nilfs_cpfile_block_init(struct inode *cpfile,
 				    struct buffer_head *bh,
-				    void *kaddr)
+				    void *from)
 {
-	struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
+	struct nilfs_checkpoint *cp = from;
 	size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
 	int n = nilfs_cpfile_checkpoints_per_block(cpfile);
 

fs/nilfs2/mdt.c

@@ -33,7 +33,8 @@ nilfs_mdt_insert_new_block(struct inode *inode, unsigned long block,
 					      struct buffer_head *, void *))
 {
 	struct nilfs_inode_info *ii = NILFS_I(inode);
-	void *kaddr;
+	struct folio *folio = bh->b_folio;
+	void *from;
 	int ret;
 
 	/* Caller exclude read accesses using page lock */
@@ -47,12 +48,14 @@ nilfs_mdt_insert_new_block(struct inode *inode, unsigned long block,
 
 	set_buffer_mapped(bh);
 
-	kaddr = kmap_local_page(bh->b_page);
-	memset(kaddr + bh_offset(bh), 0, i_blocksize(inode));
+	/* Initialize block (block size > PAGE_SIZE not yet supported) */
+	from = kmap_local_folio(folio, offset_in_folio(folio, bh->b_data));
+	memset(from, 0, bh->b_size);
 	if (init_block)
-		init_block(inode, bh, kaddr);
-	flush_dcache_page(bh->b_page);
-	kunmap_local(kaddr);
+		init_block(inode, bh, from);
+	kunmap_local(from);
+
+	flush_dcache_folio(folio);
 
 	set_buffer_uptodate(bh);
 	mark_buffer_dirty(bh);
@@ -571,7 +574,8 @@ int nilfs_mdt_freeze_buffer(struct inode *inode, struct buffer_head *bh)
 	if (!bh_frozen)
 		bh_frozen = create_empty_buffers(folio, 1 << blkbits, 0);
 
-	bh_frozen = get_nth_bh(bh_frozen, bh_offset(bh) >> blkbits);
+	bh_frozen = get_nth_bh(bh_frozen,
+			       offset_in_folio(folio, bh->b_data) >> blkbits);
 
 	if (!buffer_uptodate(bh_frozen))
 		nilfs_copy_buffer(bh_frozen, bh);
@@ -601,7 +605,8 @@ nilfs_mdt_get_frozen_buffer(struct inode *inode, struct buffer_head *bh)
 	if (!IS_ERR(folio)) {
 		bh_frozen = folio_buffers(folio);
 		if (bh_frozen) {
-			n = bh_offset(bh) >> inode->i_blkbits;
+			n = offset_in_folio(folio, bh->b_data) >>
+				inode->i_blkbits;
 			bh_frozen = get_nth_bh(bh_frozen, n);
 		}
 		folio_unlock(folio);