udf: Convert in-ICB files to use udf_writepages()

Switching address_space_operations while a file is used is difficult to
do in a race-free way. To be able to use single address_space_operations
in UDF, make in-ICB files use udf_writepages().

Reported-by: syzbot+c27475eb921c46bbdc62@syzkaller.appspotmail.com
Reported-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/udf/file.c

@@ -57,25 +57,6 @@ void udf_adinicb_readpage(struct page *page)
 	kunmap_atomic(kaddr);
 }
 
-static int udf_adinicb_writepage(struct page *page,
-				 struct writeback_control *wbc)
-{
-	struct inode *inode = page->mapping->host;
-	char *kaddr;
-	struct udf_inode_info *iinfo = UDF_I(inode);
-
-	BUG_ON(!PageLocked(page));
-
-	kaddr = kmap_atomic(page);
-	memcpy(iinfo->i_data + iinfo->i_lenEAttr, kaddr, i_size_read(inode));
-	SetPageUptodate(page);
-	kunmap_atomic(kaddr);
-	mark_inode_dirty(inode);
-	unlock_page(page);
-
-	return 0;
-}
-
 static int udf_adinicb_write_begin(struct file *file,
 			struct address_space *mapping, loff_t pos,
 			unsigned len, struct page **pagep,
@@ -119,7 +100,7 @@ const struct address_space_operations udf_adinicb_aops = {
 	.dirty_folio	= block_dirty_folio,
 	.invalidate_folio = block_invalidate_folio,
 	.read_folio	= udf_read_folio,
-	.writepage	= udf_adinicb_writepage,
+	.writepages	= udf_writepages,
 	.write_begin	= udf_adinicb_write_begin,
 	.write_end	= udf_adinicb_write_end,
 	.direct_IO	= udf_adinicb_direct_IO,

fs/udf/inode.c

@@ -185,10 +185,33 @@ static void udf_write_failed(struct address_space *mapping, loff_t to)
 	}
 }
 
-static int udf_writepages(struct address_space *mapping,
-			struct writeback_control *wbc)
+static int udf_adinicb_writepage(struct page *page,
+				 struct writeback_control *wbc, void *data)
 {
-	return mpage_writepages(mapping, wbc, udf_get_block_wb);
+	struct inode *inode = page->mapping->host;
+	char *kaddr;
+	struct udf_inode_info *iinfo = UDF_I(inode);
+
+	BUG_ON(!PageLocked(page));
+
+	kaddr = kmap_atomic(page);
+	memcpy(iinfo->i_data + iinfo->i_lenEAttr, kaddr, i_size_read(inode));
+	SetPageUptodate(page);
+	kunmap_atomic(kaddr);
+	unlock_page(page);
+	mark_inode_dirty(inode);
+
+	return 0;
+}
+
+int udf_writepages(struct address_space *mapping, struct writeback_control *wbc)
+{
+	struct inode *inode = mapping->host;
+	struct udf_inode_info *iinfo = UDF_I(inode);
+
+	if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB)
+		return mpage_writepages(mapping, wbc, udf_get_block_wb);
+	return write_cache_pages(mapping, wbc, udf_adinicb_writepage, NULL);
 }
 
 int udf_read_folio(struct file *file, struct folio *folio)

fs/udf/udfdecl.h

@@ -160,6 +160,7 @@ extern int udf_setsize(struct inode *, loff_t);
 extern void udf_evict_inode(struct inode *);
 extern int udf_write_inode(struct inode *, struct writeback_control *wbc);
 int udf_read_folio(struct file *file, struct folio *folio);
+int udf_writepages(struct address_space *mapping, struct writeback_control *wbc);
 extern int8_t inode_bmap(struct inode *, sector_t, struct extent_position *,
 			 struct kernel_lb_addr *, uint32_t *, sector_t *);
 int udf_get_block(struct inode *, sector_t, struct buffer_head *, int);