MDEV-12699 preparation: Clean up recv_sys

The recv_sys data structures are accessed not only from the thread
that executes InnoDB plugin initialization, but also from the
InnoDB I/O threads, which can invoke recv_recover_page().

Assert that sufficient concurrency control is in place.
Some code was accessing recv_sys data structures without
holding recv_sys->mutex.

recv_recover_page(bpage): Refactor the call from buf_page_io_complete()
into a separate function that performs necessary steps. The
main thread was unnecessarily releasing and reacquiring recv_sys->mutex.

recv_recover_page(block,mtr,recv_addr): Pass more parameters from
the caller. Avoid redundant lookups and computations. Eliminate some
redundant variables.

recv_get_fil_addr_struct(): Assert that recv_sys->mutex is being held.
That was not always the case!

recv_scan_log_recs(): Acquire recv_sys->mutex for the whole duration
of the function. (While we are scanning and buffering redo log records,
no pages can be read in.)

recv_read_in_area(): Properly protect access with recv_sys->mutex.

recv_apply_hashed_log_recs(): Check recv_addr->state only once,
and continuously hold recv_sys->mutex. The mutex will be released
and reacquired inside recv_recover_page() and recv_read_in_area(),
allowing concurrent processing by buf_page_io_complete() in I/O threads.

extra/mariabackup/xtrabackup.cc

@@ -2752,8 +2752,13 @@ static bool xtrabackup_copy_logfile(bool last = false)
 			my_sleep(1000);
 		}
 
-		start_lsn = (lsn == start_lsn)
-			? 0 : xtrabackup_copy_log(start_lsn, lsn, last);
+		if (lsn == start_lsn) {
+			start_lsn = 0;
+		} else {
+			mutex_enter(&recv_sys->mutex);
+			start_lsn = xtrabackup_copy_log(start_lsn, lsn, last);
+			mutex_exit(&recv_sys->mutex);
+		}
 
 		log_mutex_exit();
 

storage/innobase/buf/buf0buf.cc

@@ -6057,9 +6057,7 @@ buf_page_io_complete(buf_page_t* bpage, bool dblwr, bool evict)
 				page_not_corrupt: bpage = bpage; );
 
 		if (recv_recovery_is_on()) {
-			/* Pages must be uncompressed for crash recovery. */
-			ut_a(uncompressed);
-			recv_recover_page(TRUE, (buf_block_t*) bpage);
+			recv_recover_page(bpage);
 		}
 
 		/* If space is being truncated then avoid ibuf operation.
@@ -6079,7 +6077,7 @@ buf_page_io_complete(buf_page_t* bpage, bool dblwr, bool evict)
 					<< " encrypted. However key "
 					"management plugin or used "
 					<< "key_version " << key_version
-					<< "is not found or"
+					<< " is not found or"
 					" used encryption algorithm or method does not match."
 					" Can't continue opening the table.";
 			} else {

storage/innobase/include/log0recv.h

@@ -49,12 +49,9 @@ dberr_t
 recv_find_max_checkpoint(ulint* max_field)
 	MY_ATTRIBUTE((nonnull, warn_unused_result));
 
-/** Apply the hashed log records to the page, if the page lsn is less than the
-lsn of a log record.
-@param just_read_in	whether the page recently arrived to the I/O handler
-@param block		the page in the buffer pool */
-void
-recv_recover_page(bool just_read_in, buf_block_t* block);
+/** Apply any buffered redo log to a page that was just read from a data file.
+@param[in,out]	bpage	buffer pool page */
+ATTRIBUTE_COLD void recv_recover_page(buf_page_t* bpage);
 
 /** Start recovering from a redo log checkpoint.
 @see recv_recovery_from_checkpoint_finish