MDEV-17138 follow-up: Optimize fseg_create()

fseg_create(): Initialize FSEG_FRAG_ARRY by a single MLOG_MEMSET record.

flst_zero_addr(), flst_init(): Optimize away redundant writes.

fseg_free_page_low(): Write FIL_NULL by MLOG_MEMSET.

2 files changed, 9 insertions, 3 deletions

diff --git a/storage/innobase/include/fut0lst.h b/storage/innobase/include/fut0lst.h
index 3f68660ae89..9fa928eda23 100644
--- a/storage/innobase/include/fut0lst.h
+++ b/storage/innobase/include/fut0lst.h
@@ -85,8 +85,12 @@ inline void flst_init(buf_block_t* block, uint16_t ofs, mtr_t* mtr)
 @param[in,out]	mtr	mini-transaction */
 inline void flst_zero_addr(fil_faddr_t* faddr, mtr_t* mtr)
 {
-	mlog_memset(faddr + FIL_ADDR_PAGE, 4, 0xff, mtr);
-	mlog_write_ulint(faddr + FIL_ADDR_BYTE, 0, MLOG_2BYTES, mtr);
+	if (mach_read_from_4(faddr + FIL_ADDR_PAGE) != FIL_NULL) {
+		mlog_memset(faddr + FIL_ADDR_PAGE, 4, 0xff, mtr);
+	}
+	if (mach_read_from_2(faddr + FIL_ADDR_BYTE)) {
+		mlog_write_ulint(faddr + FIL_ADDR_BYTE, 0, MLOG_2BYTES, mtr);
+	}
 }
 
 /********************************************************************//**
diff --git a/storage/innobase/include/fut0lst.ic b/storage/innobase/include/fut0lst.ic
index 0a4f2b24738..ec4181b2c93 100644
--- a/storage/innobase/include/fut0lst.ic
+++ b/storage/innobase/include/fut0lst.ic
@@ -82,7 +82,9 @@ flst_init(
 					     MTR_MEMO_PAGE_X_FIX
 					     | MTR_MEMO_PAGE_SX_FIX));
 
-	mlog_write_ulint(base + FLST_LEN, 0, MLOG_4BYTES, mtr);
+	if (mach_read_from_4(base + FLST_LEN)) {
+		mlog_write_ulint(base + FLST_LEN, 0, MLOG_4BYTES, mtr);
+	}
 	flst_zero_addr(base + FLST_FIRST, mtr);
 	flst_zero_addr(base + FLST_LAST, mtr);
 }