Bug #21640679 ONLINE ALTER CRASHES FOR 4K PAGE SIZE

		WHEN THERE IS NO FREE EXTENT
Problem:
=======
  When a new extent is allocated to a tablespace, its xdes entry will
be put onto the FSP_FREE segment list.  But extent happens to contain
an extent descriptor page, then the extent is put into FSP_FREE_FRAG list.
Still tablespace won't find any extent in FREE_LIST. It happens only
when less than or equal to 4kb page size is used, because once the tablespace
grows to 32 extent size or 32 MB then 4 extents are allocated at a time rather
than one. For page size less than 4k only, allocation of extent contains extent
descriptor page before reaching 32 extent or MB.

Fix:
===
  Once the tablespace size reaches page_size page then allocate 4 extent
at a time.

Reviewed-by: Annamalai Gurusami <[email protected]>
Reviewed-by: Jimmy Yang <[email protected]>
RB: 10267

Author: Thirunarayanan

mysql-test/suite/innodb_zip/r/innodb_wl6347_comp_indx_stat.result

@@ -267,7 +267,7 @@ AND compress_ops BETWEEN @inl_val AND 1000
 AND table_name='tab5' AND database_name='test'
 AND index_name like 'idx%' ;
 compress_stat	1
-The size of the tab5.ibd file: 2097152
+The size of the tab5.ibd file: 5242880
 # fetch the compressed page and check the stats
 ===============
 Fetch Records
@@ -293,7 +293,7 @@ AND compress_ops BETWEEN @inl_val AND 1000
 AND table_name='tab5' AND database_name='test'
 AND index_name like 'idx%' ;
 compress_stat	1
-The size of the tab5.ibd file: 2097152
+The size of the tab5.ibd file: 5242880
 # fetch the compressed same page once again and check the stats
 # the stat figures should be same as above query
 ===============
@@ -320,7 +320,7 @@ AND compress_ops BETWEEN @inl_val AND 1000
 AND table_name='tab5' AND database_name='test'
 AND index_name like 'idx%' ;
 compress_stat	1
-The size of the tab5.ibd file: 2097152
+The size of the tab5.ibd file: 5242880
 # Restarting server
 # set the flag on (default off)
 SET GLOBAL innodb_cmp_per_index_enabled=ON;

storage/innobase/fsp/fsp0fsp.cc

@@ -952,10 +952,20 @@ fsp_try_extend_data_file(
 		}
 	} else {
 		/* We extend single-table tablespaces first one extent
-		at a time, but for bigger tablespaces more. It is not
-		enough to extend always by one extent, because some
-		extents are frag page extents. */
+		at a time, but 4 at a time for bigger tablespaces. It is
+		not enough to extend always by one extent, because we need
+		to add at least one extent to FSP_FREE.
+		A single extent descriptor page will track many extents.
+		And the extent that uses its extent descriptor page is
+		put onto the FSP_FREE_FRAG list. Extents that do not
+		use their extent descriptor page are added to FSP_FREE.
+		The physical page size is used to determine how many
+		extents are tracked on one extent descriptor page. */
 		ulint	extent_size;	/*!< one megabyte, in pages */
+		ulint	threshold;	/*!< The size of the tablespace
+					(in number of pages) where we
+					start allocating more than one
+					extent at a time. */
 
 		if (!zip_size) {
 			extent_size = FSP_EXTENT_SIZE;
@@ -964,6 +974,14 @@ fsp_try_extend_data_file(
 				* UNIV_PAGE_SIZE / zip_size;
 		}
 
+		/* Threshold is set at 32mb except when the page
+		size is small enough that it must be done sooner.
+		For page size less than 4k, we may reach the
+		extent contains extent descriptor page before
+		32 mb. */
+		threshold = ut_min((32 * extent_size),
+				   (zip_size ? zip_size : UNIV_PAGE_SIZE));
+
 		if (size < extent_size) {
 			/* Let us first extend the file to extent_size */
 			success = fsp_try_extend_data_file_with_pages(
@@ -980,7 +998,7 @@ fsp_try_extend_data_file(
 			size = extent_size;
 		}
 
-		if (size < 32 * extent_size) {
+		if (size < threshold) {
 			size_increase = extent_size;
 		} else {
 			/* Below in fsp_fill_free_list() we assume