udf: Unify .read_folio for normal and in-ICB files

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 udf_read_folio() handle both normal and in-ICB files.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/udf/file.c

@@ -38,7 +38,7 @@
 #include "udf_i.h"
 #include "udf_sb.h"
 
-static void __udf_adinicb_readpage(struct page *page)
+void udf_adinicb_readpage(struct page *page)
 {
 	struct inode *inode = page->mapping->host;
 	char *kaddr;
@@ -57,15 +57,6 @@ static void __udf_adinicb_readpage(struct page *page)
 	kunmap_atomic(kaddr);
 }
 
-static int udf_adinicb_read_folio(struct file *file, struct folio *folio)
-{
-	BUG_ON(!folio_test_locked(folio));
-	__udf_adinicb_readpage(&folio->page);
-	folio_unlock(folio);
-
-	return 0;
-}
-
 static int udf_adinicb_writepage(struct page *page,
 				 struct writeback_control *wbc)
 {
@@ -100,7 +91,7 @@ static int udf_adinicb_write_begin(struct file *file,
 	*pagep = page;
 
 	if (!PageUptodate(page))
-		__udf_adinicb_readpage(page);
+		udf_adinicb_readpage(page);
 	return 0;
 }
 
@@ -127,7 +118,7 @@ static int udf_adinicb_write_end(struct file *file, struct address_space *mappin
 const struct address_space_operations udf_adinicb_aops = {
 	.dirty_folio	= block_dirty_folio,
 	.invalidate_folio = block_invalidate_folio,
-	.read_folio	= udf_adinicb_read_folio,
+	.read_folio	= udf_read_folio,
 	.writepage	= udf_adinicb_writepage,
 	.write_begin	= udf_adinicb_write_begin,
 	.write_end	= udf_adinicb_write_end,

fs/udf/inode.c

@@ -191,8 +191,15 @@ static int udf_writepages(struct address_space *mapping,
 	return mpage_writepages(mapping, wbc, udf_get_block_wb);
 }
 
-static int udf_read_folio(struct file *file, struct folio *folio)
+int udf_read_folio(struct file *file, struct folio *folio)
 {
+	struct udf_inode_info *iinfo = UDF_I(file_inode(file));
+
+	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
+		udf_adinicb_readpage(&folio->page);
+		folio_unlock(folio);
+		return 0;
+	}
 	return mpage_read_folio(folio, udf_get_block);
 }
 

fs/udf/udfdecl.h

@@ -138,6 +138,7 @@ static inline unsigned int udf_dir_entry_len(struct fileIdentDesc *cfi)
 
 /* file.c */
 extern long udf_ioctl(struct file *, unsigned int, unsigned long);
+void udf_adinicb_readpage(struct page *page);
 
 /* inode.c */
 extern struct inode *__udf_iget(struct super_block *, struct kernel_lb_addr *,
@@ -158,6 +159,7 @@ extern struct buffer_head *udf_bread(struct inode *inode, udf_pblk_t block,
 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);
 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);