fs: export generic_file_buffered_read()

Export generic_file_buffered_read() to be used to supplement incomplete
direct reads.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

include/linux/fs.h

@@ -3124,6 +3124,8 @@ extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);
 extern int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
 				    struct file *file_out, loff_t pos_out,
 				    size_t *count, unsigned int flags);
+extern ssize_t generic_file_buffered_read(struct kiocb *iocb,
+		struct iov_iter *to, ssize_t already_read);
 extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);

mm/filemap.c

@@ -1991,7 +1991,7 @@ static void shrink_readahead_size_eio(struct file_ra_state *ra)
  * * total number of bytes copied, including those the were already @written
  * * negative error code if nothing was copied
  */
-static ssize_t generic_file_buffered_read(struct kiocb *iocb,
+ssize_t generic_file_buffered_read(struct kiocb *iocb,
 		struct iov_iter *iter, ssize_t written)
 {
 	struct file *filp = iocb->ki_filp;
@@ -2243,6 +2243,7 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 	file_accessed(filp);
 	return written ? written : error;
 }
+EXPORT_SYMBOL_GPL(generic_file_buffered_read);
 
 /**
  * generic_file_read_iter - generic filesystem read routine