MDEV-11679 Remove redundant function fsp_header_get_crypt_offset()

fsp_header_get_crypt_offset(): Remove.

xdes_arr_size(): Remove.

fsp_header_get_encryption_offset(): Make this an inline function.

The correctness of this change was ensured with the following patch
that ensures that the two functions returned the same value, only
differing by FSP_HEADER_OFFSET (38 bytes):

diff --git a/storage/innobase/fsp/fsp0fsp.cc b/storage/innobase/fsp/fsp0fsp.cc
index f2a4c6bf218..e96c788b7df 100644
--- a/storage/innobase/fsp/fsp0fsp.cc
+++ b/storage/innobase/fsp/fsp0fsp.cc
@@ -850,6 +850,7 @@ fsp_parse_init_file_page(
 	return(ptr);
 }

+static ulint fsp_header_get_encryption_offset(const page_size_t&);
 /**********************************************************************//**
 Initializes the fsp system. */
 void
@@ -868,6 +869,31 @@ fsp_init(void)
 #endif

 	/* Does nothing at the moment */
+
+	for (ulint sz = 4096; sz <= 65536; sz *= 2) {
+		ulint m;
+		if (sz <= 16384) {
+			for (ulint ph = 1024; ph <= sz; ph *= 2) {
+				const page_size_t ps(ph, sz, true);
+				ulint maria = fsp_header_get_crypt_offset(ps, &m),
+					oracle = fsp_header_get_encryption_offset(ps);
+				if (maria != oracle + 38) {
+					ib::error() << "zip size mismatch: "
+						    << maria << "!=" << oracle
+						    << "(" << ph <<","<<sz<<")"
+						    << m;
+				}
+			}
+		}
+		const page_size_t p(sz, sz, false);
+		ulint maria = fsp_header_get_crypt_offset(p, &m),
+			oracle = fsp_header_get_encryption_offset(p);
+		if (maria != oracle + 38) {
+			ib::error() << "size mismatch: "
+				    << maria << "!=" << oracle
+				    << "(" <<sz<<")" << m;
+		}
+	}
 }

 /**********************************************************************//**

storage/innobase/fil/fil0crypt.cc

@@ -1179,10 +1179,11 @@ fil_crypt_start_encrypting_space(
 
 		/* 3 - compute location to store crypt data */
 		byte* frame = buf_block_get_frame(block);
-		ulint maxsize = 0;
 		ut_ad(crypt_data);
-		crypt_data->page0_offset =
-			fsp_header_get_crypt_offset(page_size, &maxsize);
+		crypt_data->page0_offset = FSP_HEADER_OFFSET
+			+ fsp_header_get_encryption_offset(page_size);
+		const ulint maxsize = page_size.logical()
+			- crypt_data->page0_offset - FIL_PAGE_DATA_END;
 
 		/* 4 - write crypt data to page 0 */
 		fil_space_write_crypt_data_low(crypt_data,
@@ -2165,10 +2166,9 @@ fil_crypt_flush_space(
 
 		if (block && err == DB_SUCCESS) {
 			byte* frame = buf_block_get_frame(block);
-			ulint maxsize=0;
 
-			crypt_data->page0_offset =
-				fsp_header_get_crypt_offset(page_size, &maxsize);
+			crypt_data->page0_offset = FSP_HEADER_OFFSET
+				+ fsp_header_get_encryption_offset(page_size);
 
 			fil_space_write_crypt_data(space, frame,
 						crypt_data->page0_offset,

storage/innobase/fil/fil0fil.cc

@@ -6661,12 +6661,11 @@ fil_tablespace_iterate(
 		iter.n_io_buffers = n_io_buffers;
 		iter.page_size = callback.get_page_size().physical();
 
-		ulint crypt_data_offset = fsp_header_get_crypt_offset(
-			callback.get_page_size(), 0);
-
 		/* read (optional) crypt data */
 		iter.crypt_data = fil_space_read_crypt_data(
-			0, page, crypt_data_offset);
+			0, page, FSP_HEADER_OFFSET
+			+ fsp_header_get_encryption_offset(
+				callback.get_page_size()));
 
 #ifdef MYSQL_ENCRYPTION
 		/* Set encryption info. */
@@ -7612,8 +7611,9 @@ fil_space_get_crypt_data(
 			fil_read(page_id_t(space_id, 0), univ_page_size, 0, univ_page_size.physical(),
 				 page);
 			ulint flags = fsp_header_get_flags(page);
-			ulint offset = fsp_header_get_crypt_offset(
-				page_size_t(flags), NULL);
+			ulint offset = FSP_HEADER_OFFSET
+				+ fsp_header_get_encryption_offset(
+					page_size_t(flags));
 			space->crypt_data = fil_space_read_crypt_data(space_id, page, offset);
 			ut_free(buf);
 

storage/innobase/fsp/fsp0file.cc

@@ -368,9 +368,10 @@ Datafile::read_first_page(bool read_only_mode)
 		m_space_id = fsp_header_get_space_id(m_first_page);
 	}
 
-	const page_size_t page_sz = fsp_header_get_page_size(m_first_page);
-	ulint offset = fsp_header_get_crypt_offset(page_sz, NULL);
-	m_crypt_info = fil_space_read_crypt_data(m_space_id, m_first_page, offset);
+	m_crypt_info = fil_space_read_crypt_data(
+		m_space_id, m_first_page,
+		FSP_HEADER_OFFSET + fsp_header_get_encryption_offset(
+			fsp_header_get_page_size(m_first_page)));
 
 	return(err);
 }

storage/innobase/fsp/fsp0fsp.cc

@@ -890,29 +890,6 @@ fsp_header_init_fields(
 }
 
 #ifndef UNIV_HOTBACKUP
-/** Get the offset of encrytion information in page 0.
-@param[in]	page_size	page size.
-@return	offset on success, otherwise 0. */
-static
-ulint
-fsp_header_get_encryption_offset(
-	const page_size_t&	page_size)
-{
-	ulint	offset;
-#ifdef UNIV_DEBUG
-	ulint	left_size;
-#endif
-
-	offset = XDES_ARR_OFFSET + XDES_SIZE * xdes_arr_size(page_size);
-#ifdef UNIV_DEBUG
-	left_size = page_size.physical() - FSP_HEADER_OFFSET - offset
-		- FIL_PAGE_DATA_END;
-
-	ut_ad(left_size >= ENCRYPTION_INFO_SIZE_V2);
-#endif
-
-	return offset;
-}
 
 #if 0 /* MySQL 5.7 Encryption */
 /** Fill the encryption info.
@@ -1180,9 +1157,11 @@ fsp_header_init(
 		}
 	}
 
-	ulint maxsize = 0;
-	ulint offset = fsp_header_get_crypt_offset(page_size, &maxsize);
-	fil_space_write_crypt_data(space_id, page, offset, maxsize, mtr);
+	ulint offset = FSP_HEADER_OFFSET
+		+ fsp_header_get_encryption_offset(page_size);
+	fil_space_write_crypt_data(space_id, page, offset,
+				   page_size.logical()
+				   - offset - FIL_PAGE_DATA_END, mtr);
 
 	return(true);
 }
@@ -4342,35 +4321,3 @@ fsp_page_is_free_func(
 	return xdes_mtr_get_bit(
 		descr, XDES_FREE_BIT, page_no % FSP_EXTENT_SIZE, mtr);
 }
-
-/**********************************************************************//**
-Compute offset after xdes where crypt data can be stored
-@return	offset */
-ulint
-fsp_header_get_crypt_offset(
-/*========================*/
-	const page_size_t&	page_size,/*!< in: page size */
-	ulint* 			max_size) /*!< out: free space available for crypt data */
-{
-	ulint pageno = 0;
-	/* compute first page_no that will have xdes stored on page != 0*/
-
-	for (ulint i = 0;
-	     (pageno = xdes_calc_descriptor_page(page_size, i)) == 0; )
-		i++;
-
-	/* use pageno prior to this...i.e last page on page 0 */
-	ut_ad(pageno > 0);
-	pageno--;
-
-	ulint iv_offset = XDES_ARR_OFFSET +
-		XDES_SIZE * (1 + xdes_calc_descriptor_index(page_size, pageno));
-
-	if (max_size != NULL) {
-		/* return how much free space there is available on page */
-		*max_size = (page_size.logical() ? page_size.logical() : UNIV_PAGE_SIZE) -
-			(FSP_HEADER_OFFSET + iv_offset + FIL_PAGE_DATA_END);
-	}
-
-	return FSP_HEADER_OFFSET + iv_offset;
-}

storage/innobase/include/fsp0fsp.h

@@ -361,6 +361,16 @@ fsp_header_get_encryption_key(
 	byte*		iv,
 	page_t*		page);
 
+/** Get the byte offset of encryption information in page 0.
+@param[in]	ps	page size
+@return	byte offset relative to FSP_HEADER_OFFSET */
+inline MY_ATTRIBUTE((pure, warn_unused_result))
+ulint
+fsp_header_get_encryption_offset(const page_size_t& ps)
+{
+	return XDES_ARR_OFFSET + XDES_SIZE * ps.physical() / FSP_EXTENT_SIZE;
+}
+
 /** Check the encryption key from the first page of a tablespace.
 @param[in]	fsp_flags	tablespace flags
 @param[in]	page		first page of a tablespace
@@ -770,20 +780,6 @@ xdes_calc_descriptor_page(
 	const page_size_t&	page_size,
 	ulint			offset);
 
-#endif /* !UNIV_INNOCHECKSUM */
-
-/*********************************************************************//**
-@return offset into fsp header where crypt data is stored */
-UNIV_INTERN
-ulint
-fsp_header_get_crypt_offset(
-/*========================*/
-	const page_size_t&	page_size,/*!< in: page size */
-	ulint* max_size);	/*!< out: free space after offset */
-
-
-#ifndef UNIV_INNOCHECKSUM
-
 /**********************************************************************//**
 Checks if a single page is free.
 @return	true if free */

storage/innobase/include/fsp0fsp.ic

@@ -337,15 +337,4 @@ xdes_calc_descriptor_page(
 
 	return(ut_2pow_round(offset, page_size.physical()));
 }
-
-/** Calculates the descriptor array size.
-@param[in]	page_size	page size
-@return size of descriptor array */
-UNIV_INLINE
-ulint
-xdes_arr_size(
-	const page_size_t&	page_size)
-{
-	return(page_size.physical()/FSP_EXTENT_SIZE);
-}
 #endif /* !UNIV_INNOCHECKSUM */