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

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_write_begin().
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_write_begin(struct file *file,
-			struct address_space *mapping, loff_t pos,
-			unsigned len, struct page **pagep,
-			void **fsdata)
-{
-	struct page *page;
-
-	if (WARN_ON_ONCE(pos >= PAGE_SIZE))
-		return -EIO;
-	page = grab_cache_page_write_begin(mapping, 0);
-	if (!page)
-		return -ENOMEM;
-	*pagep = page;
-
-	if (!PageUptodate(page))
-		udf_adinicb_readpage(page);
-	return 0;
-}
-
 static int udf_adinicb_write_end(struct file *file, struct address_space *mapping,
 				 loff_t pos, unsigned len, unsigned copied,
 				 struct page *page, void *fsdata)
@@ -95,7 +76,7 @@ const struct address_space_operations udf_adinicb_aops = {
 	.invalidate_folio = block_invalidate_folio,
 	.read_folio	= udf_read_folio,
 	.writepages	= udf_writepages,
-	.write_begin	= udf_adinicb_write_begin,
+	.write_begin	= udf_write_begin,
 	.write_end	= udf_adinicb_write_end,
 	.direct_IO	= udf_direct_IO,
 };

fs/udf/inode.c

@@ -231,16 +231,30 @@ static void udf_readahead(struct readahead_control *rac)
 	mpage_readahead(rac, udf_get_block);
 }
 
-static int udf_write_begin(struct file *file, struct address_space *mapping,
+int udf_write_begin(struct file *file, struct address_space *mapping,
 			loff_t pos, unsigned len,
 			struct page **pagep, void **fsdata)
 {
+	struct udf_inode_info *iinfo = UDF_I(file_inode(file));
+	struct page *page;
 	int ret;
 
-	ret = block_write_begin(mapping, pos, len, pagep, udf_get_block);
-	if (unlikely(ret))
-		udf_write_failed(mapping, pos + len);
-	return ret;
+	if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB) {
+		ret = block_write_begin(mapping, pos, len, pagep,
+					udf_get_block);
+		if (unlikely(ret))
+			udf_write_failed(mapping, pos + len);
+		return ret;
+	}
+	if (WARN_ON_ONCE(pos >= PAGE_SIZE))
+		return -EIO;
+	page = grab_cache_page_write_begin(mapping, 0);
+	if (!page)
+		return -ENOMEM;
+	*pagep = page;
+	if (!PageUptodate(page))
+		udf_adinicb_readpage(page);
+	return 0;
 }
 
 ssize_t udf_direct_IO(struct kiocb *iocb, struct iov_iter *iter)

fs/udf/udfdecl.h

@@ -161,6 +161,9 @@ 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);
+int udf_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len,
+			struct page **pagep, void **fsdata);
 ssize_t udf_direct_IO(struct kiocb *iocb, struct iov_iter *iter);
 extern int8_t inode_bmap(struct inode *, sector_t, struct extent_position *,
 			 struct kernel_lb_addr *, uint32_t *, sector_t *);