MDEV-18976 Implement OPT_PAGE_CHECKSUM log record for improved validation

We will introduce an optional log record OPT_PAGE_CHECKSUM for recording
page checksums, so that more inconsistencies on crash recovery may be
caught.

mtr_t::page_checksum(const buf_page_t&): Write OPT_PAGE_CHECKSUM
(currently not for ROW_FORMAT=COMPRESSED pages).

mtr_t::do_write(): Write OPT_PAGE_CHECKSUM records for all pages
(currently, in debug builds only).

mtr_t::is_logged(): Return whether log should be written.

mtr_t::set_log_mode_sub(const mtr_t&): Set the logging mode of
a sub-minitransaction when another mini-transaction is holding
latches on some modified pages. When creating or freeing BLOB pages,
we may only write OPT_PAGE_CHECKSUM records in the main mini-transaction,
after all changes have been written to the log.

MTR_LOG_SUB: Log mode for a sub-mini-transaction.

mtr_t::free(): Define non-inline, and invoke MarkFreed.

MarkFreed: For any matching page in the mini-transaction log,
change the first entry to say MTR_MEMO_PAGE_X_MODIFY and any subsequent
entries to MTR_MEMO_PAGE_X_FIX.

FindModified: Simplify a condition. MTR_MEMO_MODIFY can only be set
if MTR_MEMO_PAGE_X_FIX or MTR_MEMO_PAGE_SX_FIX are set.

FindBlockX: Consider also MTR_MEMO_PAGE_X_MODIFY.

recv_sys_t::parse(): Store OPT_PAGE_CHECKSUM records.

log_phys_t::apply(): Validate OPT_PAGE_CHECKSUM records.

log_phys_t::page_checksum(): Validate an OPT_PAGE_CHECKSUM record.

Tested by: Matthias Leich

12 files changed, 275 insertions, 124 deletions

diff --git a/storage/innobase/btr/btr0cur.cc b/storage/innobase/btr/btr0cur.cc
index abab6ab876b..adce2ed2b6f 100644
--- a/storage/innobase/btr/btr0cur.cc
+++ b/storage/innobase/btr/btr0cur.cc
@@ -6943,7 +6943,7 @@ btr_store_big_rec_extern_fields(
 
 			mtr.start();
 			index->set_modified(mtr);
-			mtr.set_log_mode(btr_mtr->get_log_mode());
+			mtr.set_log_mode_sub(*btr_mtr);
 			mtr.memo_push(rec_block, MTR_MEMO_PAGE_X_FIX);
 
 			rec_block->page.fix();
@@ -7287,7 +7287,7 @@ btr_free_externally_stored_field(
 
 		mtr.start();
 		mtr.set_spaces(*local_mtr);
-		mtr.set_log_mode(local_mtr->get_log_mode());
+		mtr.set_log_mode_sub(*local_mtr);
 
 		ut_ad(!index->table->is_temporary()
 		      || local_mtr->get_log_mode() == MTR_LOG_NO_REDO);
diff --git a/storage/innobase/fil/fil0fil.cc b/storage/innobase/fil/fil0fil.cc
index 703638f2b7c..07f77add744 100644
--- a/storage/innobase/fil/fil0fil.cc
+++ b/storage/innobase/fil/fil0fil.cc
@@ -1483,7 +1483,7 @@ inline void mtr_t::log_file_op(mfile_type_t type, ulint space_id,
   ut_ad(!strcmp(&path[strlen(path) - strlen(DOT_IBD)], DOT_IBD));
 
   flag_modified();
-  if (m_log_mode != MTR_LOG_ALL)
+  if (!is_logged())
     return;
   m_last= nullptr;
 
diff --git a/storage/innobase/fsp/fsp0fsp.cc b/storage/innobase/fsp/fsp0fsp.cc
index b1cf62fc160..54a43b920bb 100644
--- a/storage/innobase/fsp/fsp0fsp.cc
+++ b/storage/innobase/fsp/fsp0fsp.cc
@@ -475,26 +475,20 @@ updating an allocation bitmap page.
 @param[in]	mtr	mini-transaction */
 void fil_space_t::modify_check(const mtr_t& mtr) const
 {
-	switch (mtr.get_log_mode()) {
-	case MTR_LOG_NONE:
-		/* These modes are only allowed within a non-bitmap page
-		when there is a higher-level redo log record written. */
-		ut_ad(purpose == FIL_TYPE_TABLESPACE
-		      || purpose == FIL_TYPE_TEMPORARY);
-		break;
-	case MTR_LOG_NO_REDO:
-		ut_ad(purpose == FIL_TYPE_TEMPORARY
-		      || purpose == FIL_TYPE_IMPORT);
-		return;
-	case MTR_LOG_ALL:
-		/* We may only write redo log for a persistent
-		tablespace. */
-		ut_ad(purpose == FIL_TYPE_TABLESPACE);
-		ut_ad(mtr.is_named_space(id));
-		return;
-	}
-
-	ut_ad("invalid log mode" == 0);
+  switch (mtr.get_log_mode()) {
+  case MTR_LOG_NONE:
+    /* These modes are only allowed within a non-bitmap page
+       when there is a higher-level redo log record written. */
+    ut_ad(purpose == FIL_TYPE_TABLESPACE || purpose == FIL_TYPE_TEMPORARY);
+    break;
+  case MTR_LOG_NO_REDO:
+    ut_ad(purpose == FIL_TYPE_TEMPORARY || purpose == FIL_TYPE_IMPORT);
+    break;
+  default:
+    /* We may only write redo log for a persistent tablespace. */
+    ut_ad(purpose == FIL_TYPE_TABLESPACE);
+    ut_ad(mtr.is_named_space(id));
+  }
 }
 #endif
 
diff --git a/storage/innobase/include/buf0buf.h b/storage/innobase/include/buf0buf.h
index 22a07e8d86a..9440672aba1 100644
--- a/storage/innobase/include/buf0buf.h
+++ b/storage/innobase/include/buf0buf.h
@@ -24,8 +24,7 @@ The database buffer pool high-level routines
 Created 11/5/1995 Heikki Tuuri
 *******************************************************/
 
-#ifndef buf0buf_h
-#define buf0buf_h
+#pragma once
 
 /** Magic value to use instead of checksums when they are disabled */
 #define BUF_NO_CHECKSUM_MAGIC 0xDEADBEEFUL
@@ -2201,5 +2200,3 @@ struct	CheckUnzipLRUAndLRUList {
 #include "buf0buf.inl"
 
 #endif /* !UNIV_INNOCHECKSUM */
-
-#endif
diff --git a/storage/innobase/include/fil0fil.h b/storage/innobase/include/fil0fil.h
index aff5109300a..8889604a919 100644
--- a/storage/innobase/include/fil0fil.h
+++ b/storage/innobase/include/fil0fil.h
@@ -1278,8 +1278,9 @@ struct fil_addr_t {
 
 /** For the first page in a system tablespace data file(ibdata*, not *.ibd):
 the file has been flushed to disk at least up to this lsn
-For other pages: 32-bit key version used to encrypt the page + 32-bit checksum
-or 64 bites of zero if no encryption */
+For other pages of tablespaces not in innodb_checksum_algorithm=full_crc32
+format: 32-bit key version used to encrypt the page + 32-bit checksum
+or 64 bits of zero if no encryption */
 #define FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION 26U
 
 /** This overloads FIL_PAGE_FILE_FLUSH_LSN for RTREE Split Sequence Number */
diff --git a/storage/innobase/include/mtr0log.h b/storage/innobase/include/mtr0log.h
index 8192c93a8f9..093b706c1de 100644
--- a/storage/innobase/include/mtr0log.h
+++ b/storage/innobase/include/mtr0log.h
@@ -196,7 +196,7 @@ inline bool mtr_t::write(const buf_block_t &block, void *ptr, V val)
   }
   byte *p= static_cast<byte*>(ptr);
   const byte *const end= p + l;
-  if (w != FORCED && m_log_mode == MTR_LOG_ALL)
+  if (w != FORCED && is_logged())
   {
     const byte *b= buf;
     while (*p++ == *b++)
@@ -224,7 +224,7 @@ inline void mtr_t::memset(const buf_block_t &b, ulint ofs, ulint len, byte val)
 {
   ut_ad(len);
   set_modified(b);
-  if (m_log_mode != MTR_LOG_ALL)
+  if (!is_logged())
     return;
 
   static_assert(MIN_4BYTE > UNIV_PAGE_SIZE_MAX, "consistency");
@@ -261,7 +261,7 @@ inline void mtr_t::memset(const buf_block_t &b, ulint ofs, size_t len,
   ut_ad(size);
   ut_ad(len > size); /* use mtr_t::memcpy() for shorter writes */
   set_modified(b);
-  if (m_log_mode != MTR_LOG_ALL)
+  if (!is_logged())
     return;
 
   static_assert(MIN_4BYTE > UNIV_PAGE_SIZE_MAX, "consistency");
@@ -319,7 +319,7 @@ inline void mtr_t::memcpy_low(const buf_block_t &block, uint16_t offset,
 {
   ut_ad(len);
   set_modified(block);
-  if (m_log_mode != MTR_LOG_ALL)
+  if (!is_logged())
     return;
   if (len < mtr_buf_t::MAX_DATA_SIZE - (1 + 3 + 3 + 5 + 5))
   {
@@ -354,7 +354,7 @@ inline void mtr_t::memmove(const buf_block_t &b, ulint d, ulint s, ulint len)
   ut_ad(d + len <= ulint(srv_page_size));
 
   set_modified(b);
-  if (m_log_mode != MTR_LOG_ALL)
+  if (!is_logged())
     return;
   static_assert(MIN_4BYTE > UNIV_PAGE_SIZE_MAX, "consistency");
   size_t lenlen= (len < MIN_2BYTE ? 1 : len < MIN_3BYTE ? 2 : 3);
@@ -387,7 +387,7 @@ template<byte type>
 inline byte *mtr_t::log_write(const page_id_t id, const buf_page_t *bpage,
                               size_t len, bool alloc, size_t offset)
 {
-  static_assert(!(type & 15) && type != RESERVED && type != OPTION &&
+  static_assert(!(type & 15) && type != RESERVED &&
                 type <= FILE_CHECKPOINT, "invalid type");
   ut_ad(type >= FILE_CREATE || is_named_space(id.space()));
   ut_ad(!bpage || bpage->id() == id);
@@ -491,7 +491,7 @@ inline void mtr_t::memcpy(const buf_block_t &b, void *dest, const void *str,
   ut_ad(ut_align_down(dest, srv_page_size) == b.page.frame);
   char *d= static_cast<char*>(dest);
   const char *s= static_cast<const char*>(str);
-  if (w != FORCED && m_log_mode == MTR_LOG_ALL)
+  if (w != FORCED && is_logged())
   {
     ut_ad(len);
     const char *const end= d + len;
@@ -531,35 +531,20 @@ inline void mtr_t::init(buf_block_t *b)
 
   b->page.set_reinit(b->page.state() & buf_page_t::LRU_MASK);
 
-  if (m_log_mode != MTR_LOG_ALL)
-  {
-    ut_ad(m_log_mode == MTR_LOG_NONE || m_log_mode == MTR_LOG_NO_REDO);
+  if (!is_logged())
     return;
-  }
 
   m_log.close(log_write<INIT_PAGE>(b->page.id(), &b->page));
   m_last_offset= FIL_PAGE_TYPE;
 }
 
-/** Free a page.
-@param[in]	space 	tablespace contains page to be freed
-@param[in]	offset	page offset to be freed */
-inline void mtr_t::free(fil_space_t &space, uint32_t offset)
-{
-  ut_ad(is_named_space(&space));
-  ut_ad(!m_freed_space || m_freed_space == &space);
-
-  if (m_log_mode == MTR_LOG_ALL)
-    m_log.close(log_write<FREE_PAGE>({space.id, offset}, nullptr));
-}
-
 /** Write an EXTENDED log record.
 @param block  buffer pool page
 @param type   extended record subtype; @see mrec_ext_t */
 inline void mtr_t::log_write_extended(const buf_block_t &block, byte type)
 {
   set_modified(block);
-  if (m_log_mode != MTR_LOG_ALL)
+  if (!is_logged())
     return;
   byte *l= log_write<EXTENDED>(block.page.id(), &block.page, 1, true);
   *l++= type;
@@ -586,7 +571,7 @@ inline void mtr_t::page_delete(const buf_block_t &block, ulint prev_rec)
   ut_ad(!block.zip_size());
   ut_ad(prev_rec < block.physical_size());
   set_modified(block);
-  if (m_log_mode != MTR_LOG_ALL)
+  if (!is_logged())
     return;
   size_t len= (prev_rec < MIN_2BYTE ? 2 : prev_rec < MIN_3BYTE ? 3 : 4);
   byte *l= log_write<EXTENDED>(block.page.id(), &block.page, len, true);
@@ -613,7 +598,7 @@ inline void mtr_t::page_delete(const buf_block_t &block, ulint prev_rec,
   ut_ad(hdr_size < MIN_3BYTE);
   ut_ad(prev_rec < block.physical_size());
   ut_ad(data_size < block.physical_size());
-  if (m_log_mode != MTR_LOG_ALL)
+  if (!is_logged())
     return;
   size_t len= prev_rec < MIN_2BYTE ? 2 : prev_rec < MIN_3BYTE ? 3 : 4;
   len+= hdr_size < MIN_2BYTE ? 1 : 2;
@@ -645,7 +630,7 @@ inline void mtr_t::undo_append(const buf_block_t &block,
 {
   ut_ad(len > 2);
   set_modified(block);
-  if (m_log_mode != MTR_LOG_ALL)
+  if (!is_logged())
     return;
   const bool small= len + 1 < mtr_buf_t::MAX_DATA_SIZE - (1 + 3 + 3 + 5 + 5);
   byte *end= log_write<EXTENDED>(block.page.id(), &block.page, len + 1, small);
@@ -668,7 +653,7 @@ inline void mtr_t::undo_append(const buf_block_t &block,
 @param id       first page identifier that will not be in the file */
 inline void mtr_t::trim_pages(const page_id_t id)
 {
-  if (m_log_mode != MTR_LOG_ALL)
+  if (!is_logged())
     return;
   byte *l= log_write<EXTENDED>(id, nullptr, 1, true);
   *l++= TRIM_PAGES;
diff --git a/storage/innobase/include/mtr0mtr.h b/storage/innobase/include/mtr0mtr.h
index 3208e492c2f..02f469e3a53 100644
--- a/storage/innobase/include/mtr0mtr.h
+++ b/storage/innobase/include/mtr0mtr.h
@@ -136,10 +136,18 @@ struct mtr_t {
   mtr_log_t get_log_mode() const
   {
     static_assert(MTR_LOG_ALL == 0, "efficiency");
-    ut_ad(m_log_mode <= MTR_LOG_NO_REDO);
     return static_cast<mtr_log_t>(m_log_mode);
   }
 
+  /** @return whether log is to be written for changes */
+  bool is_logged() const
+  {
+    static_assert(MTR_LOG_ALL == 0, "efficiency");
+    static_assert(MTR_LOG_NONE & MTR_LOG_NO_REDO, "efficiency");
+    static_assert(!(MTR_LOG_NONE & MTR_LOG_SUB), "efficiency");
+    return !(m_log_mode & MTR_LOG_NONE);
+  }
+
   /** Change the logging mode.
   @param mode	 logging mode
   @return	old mode */
@@ -150,6 +158,15 @@ struct mtr_t {
     return old_mode;
   }
 
+  /** Set the log mode of a sub-minitransaction
+  @param mtr  parent mini-transaction */
+  void set_log_mode_sub(const mtr_t &mtr)
+  {
+    ut_ad(mtr.m_log_mode == MTR_LOG_ALL || mtr.m_log_mode == MTR_LOG_NO_REDO);
+    m_log_mode= mtr.m_log_mode | MTR_LOG_SUB;
+    static_assert((MTR_LOG_SUB | MTR_LOG_NO_REDO) == MTR_LOG_NO_REDO, "");
+  }
+
   /** Check if we are holding a block latch in exclusive mode
   @param block  buffer pool block to search for */
   bool have_x_latch(const buf_block_t &block) const;
@@ -372,6 +389,9 @@ public:
   /** @return whether the log and memo are empty */
   bool is_empty() const { return m_memo.size() == 0 && m_log.size() == 0; }
 
+  /** Write an OPT_PAGE_CHECKSUM record. */
+  inline void page_checksum(const buf_page_t &bpage);
+
   /** Write request types */
   enum write_type
   {
@@ -470,9 +490,9 @@ public:
   @param[in,out]        b       buffer page */
   void init(buf_block_t *b);
   /** Free a page.
-  @param[in]      space   tablespace contains page to be freed
-  @param[in]      offset  page offset to be freed */
-  inline void free(fil_space_t &space, uint32_t offset);
+  @param space   tablespace
+  @param offset  offset of the page to be freed */
+  void free(const fil_space_t &space, uint32_t offset);
   /** Write log for partly initializing a B-tree or R-tree page.
   @param block    B-tree or R-tree page
   @param comp     false=ROW_FORMAT=REDUNDANT, true=COMPACT or DYNAMIC */
diff --git a/storage/innobase/include/mtr0types.h b/storage/innobase/include/mtr0types.h
index 9ee7810fa7b..7acc255da36 100644
--- a/storage/innobase/include/mtr0types.h
+++ b/storage/innobase/include/mtr0types.h
@@ -41,6 +41,11 @@ enum mtr_log_t {
 	Set for attempting modification of a ROW_FORMAT=COMPRESSED page. */
 	MTR_LOG_NONE,
 
+	/** Log all operations, but do not write any OPT_PAGE_CHECKSUM
+	records because some of the modified pages were also modified
+	by another mini-transaction that did not write its log yet. */
+	MTR_LOG_SUB,
+
 	/** Don't generate REDO log but add dirty pages to flush list */
 	MTR_LOG_NO_REDO
 };
@@ -77,12 +82,8 @@ type. The following record types refer to data pages:
     RESERVED (6): reserved for future use; a subtype code
     (encoded immediately after the length) would be written
     to reserve code space for further extensions
-    OPTION (7): optional record that may be ignored; a subtype code
-    (encoded immediately after the length) would distinguish actual
-    usage, such as:
-     * MDEV-18976 page checksum record
-     * binlog record
-     * SQL statement (at the start of statement)
+    OPTION (7): optional record that may be ignored; a subtype @see mrec_opt
+    (encoded immediately after the length) would distinguish actual usage
 
 Bits 3..0 indicate the redo log record length, excluding the first
 byte, but including additional length bytes and any other bytes,
@@ -229,9 +230,7 @@ enum mrec_type_t
   /** Reserved for future use. */
   RESERVED= 0x60,
   /** Optional record that may be ignored in crash recovery.
-  A subtype code will be encoded immediately after the length.
-  Possible subtypes would include a MDEV-18976 page checksum record,
-  a binlog record, or an SQL statement. */
+  A subtype (@see mrec_opt) will be encoded after the page identifier. */
   OPTION= 0x70
 };
 
@@ -283,6 +282,15 @@ enum mrec_ext_t
 };
 
 
+/** Recognized OPTION record subtypes. */
+enum mrec_opt
+{
+  /** page checksum at the end of the mini-transaction */
+  OPT_PAGE_CHECKSUM= 0
+  /* Other possible subtypes: a binlog record, or an SQL statement. */
+};
+
+
 /** Redo log record types for file-level operations. These bit
 patterns will be written to redo log files, so the existing codes or
 their interpretation on crash recovery must not be changed. */
diff --git a/storage/innobase/log/log0recv.cc b/storage/innobase/log/log0recv.cc
index 6f120d2c7fd..377c08b9290 100644
--- a/storage/innobase/log/log0recv.cc
+++ b/storage/innobase/log/log0recv.cc
@@ -54,6 +54,7 @@ Created 9/20/1997 Heikki Tuuri
 #include "srv0srv.h"
 #include "srv0start.h"
 #include "fil0pagecompress.h"
+#include "log.h"
 
 /** The recovery system */
 recv_sys_t	recv_sys;
@@ -86,7 +87,7 @@ is bigger than the lsn we are able to scan up to, that is an indication that
 the recovery failed and the database may be corrupt. */
 static lsn_t	recv_max_page_lsn;
 
-/** Stored physical log record with logical LSN (@see log_t::FORMAT_10_5) */
+/** Stored physical log record */
 struct log_phys_t : public log_rec_t
 {
   /** start LSN of the mini-transaction (not necessarily of this record) */
@@ -178,6 +179,35 @@ public:
     return false;
   }
 
+  /** Check an OPT_PAGE_CHECKSUM record.
+  @see mtr_t::page_checksum()
+  @param block   buffer page
+  @param l       pointer to checksum
+  @return whether an unrecoverable mismatch was found */
+  static bool page_checksum(const buf_block_t &block, const byte *l)
+  {
+    size_t size;
+    const byte *page= block.page.zip.data;
+    if (UNIV_LIKELY_NULL(page))
+      size= (UNIV_ZIP_SIZE_MIN >> 1) << block.page.zip.ssize;
+    else
+    {
+      page= block.page.frame;
+      size= srv_page_size;
+    }
+    if (UNIV_LIKELY(my_crc32c(my_crc32c(my_crc32c(0, page + FIL_PAGE_OFFSET,
+                                                  FIL_PAGE_LSN -
+                                                  FIL_PAGE_OFFSET),
+                                        page + FIL_PAGE_TYPE, 2),
+                              page + FIL_PAGE_SPACE_ID,
+                              size - (FIL_PAGE_SPACE_ID + 8)) ==
+                    mach_read_from_4(l)))
+      return false;
+
+    ib::error() << "OPT_PAGE_CHECKSUM mismatch on " << block.page.id();
+    return !srv_force_recovery;
+  }
+
   /** The status of apply() */
   enum apply_status {
     /** The page was not affected */
@@ -262,9 +292,21 @@ public:
       next_not_same_page:
           last_offset= 1; /* the next record must not be same_page  */
         }
-      next:
         l+= rlen;
         continue;
+      case OPTION:
+        ut_ad(rlen == 5);
+        ut_ad(*l == OPT_PAGE_CHECKSUM);
+        if (page_checksum(block, l + 1))
+        {
+          applied= APPLIED_YES;
+page_corrupted:
+          sql_print_error("InnoDB: Set innodb_force_recovery=1"
+                          " to ignore corruption.");
+          recv_sys.set_corrupt_log();
+          return applied;
+        }
+        goto next_after_applying;
       }
 
       ut_ad(mach_read_from_4(frame + FIL_PAGE_OFFSET) ==
@@ -275,8 +317,6 @@ public:
       ut_ad(last_offset <= size);
 
       switch (b & 0x70) {
-      case OPTION:
-        goto next;
       case EXTENDED:
         if (UNIV_UNLIKELY(block.page.id().page_no() < 3 ||
                           block.page.zip.ssize))
@@ -305,12 +345,7 @@ public:
           if (UNIV_UNLIKELY(rlen <= 3))
             goto record_corrupted;
           if (undo_append(block, ++l, --rlen) && !srv_force_recovery)
-          {
-page_corrupted:
-            ib::error() << "Set innodb_force_recovery=1 to ignore corruption.";
-            recv_sys.set_corrupt_log();
-            return applied;
-          }
+            goto page_corrupted;
           break;
         case INSERT_HEAP_REDUNDANT:
         case INSERT_REUSE_REDUNDANT:
@@ -2334,7 +2369,8 @@ same_page:
     if (got_page_op)
     {
       const page_id_t id(space_id, page_no);
-      ut_d(if ((b & 0x70) == INIT_PAGE) freed.erase(id));
+      ut_d(if ((b & 0x70) == INIT_PAGE || (b & 0x70) == OPTION)
+             freed.erase(id));
       ut_ad(freed.find(id) == freed.end());
       switch (b & 0x70) {
       case FREE_PAGE:
@@ -2370,8 +2406,11 @@ same_page:
         }
         last_offset= FIL_PAGE_TYPE;
         break;
-      case RESERVED:
       case OPTION:
+        if (rlen == 5 && *l == OPT_PAGE_CHECKSUM)
+          break;
+        /* fall through */
+      case RESERVED:
         continue;
       case WRITE:
       case MEMMOVE:
@@ -2463,9 +2502,9 @@ same_page:
 #if 0 && defined UNIV_DEBUG
       switch (b & 0x70) {
       case RESERVED:
-      case OPTION:
         ut_ad(0); /* we did "continue" earlier */
         break;
+      case OPTION:
       case FREE_PAGE:
         break;
       default:
diff --git a/storage/innobase/mtr/mtr0mtr.cc b/storage/innobase/mtr/mtr0mtr.cc
index af3ac0c626c..4a5b5f7124a 100644
--- a/storage/innobase/mtr/mtr0mtr.cc
+++ b/storage/innobase/mtr/mtr0mtr.cc
@@ -375,8 +375,8 @@ struct ReleaseBlocks
       return true;
     }
 
-    buf_flush_note_modification(static_cast<buf_block_t*>(slot->object),
-                                start, end);
+    buf_block_t *block= static_cast<buf_block_t*>(slot->object);
+    buf_flush_note_modification(block, start, end);
     return true;
   }
 };
@@ -436,7 +436,7 @@ void mtr_t::commit()
 
     std::pair<lsn_t,page_flush_ahead> lsns;
 
-    if (UNIV_LIKELY(m_log_mode == MTR_LOG_ALL))
+    if (UNIV_LIKELY(is_logged()))
     {
       lsns= do_write();
 
@@ -577,6 +577,7 @@ void mtr_t::commit_shrink(fil_space_t &space)
   log_write_and_flush_prepare();
 
   const lsn_t start_lsn= do_write().first;
+  ut_d(m_log.erase());
 
   mysql_mutex_lock(&log_sys.flush_order_mutex);
   /* Durably write the reduced FSP_SIZE before truncating the data file. */
@@ -673,19 +674,9 @@ void mtr_t::commit_files(lsn_t checkpoint_lsn)
 bool
 mtr_t::is_named_space(ulint space) const
 {
-	ut_ad(!m_user_space || m_user_space->id != TRX_SYS_SPACE);
-
-	switch (m_log_mode) {
-	case MTR_LOG_NONE:
-	case MTR_LOG_NO_REDO:
-		return(true);
-	case MTR_LOG_ALL:
-		return(m_user_space_id == space
-		       || is_predefined_tablespace(space));
-	}
-
-	ut_error;
-	return(false);
+  ut_ad(!m_user_space || m_user_space->id != TRX_SYS_SPACE);
+  return !is_logged() || m_user_space_id == space ||
+    is_predefined_tablespace(space);
 }
 /** Check if a tablespace is associated with the mini-transaction
 (needed for generating a FILE_MODIFY record)
@@ -695,16 +686,8 @@ bool mtr_t::is_named_space(const fil_space_t* space) const
 {
   ut_ad(!m_user_space || m_user_space->id != TRX_SYS_SPACE);
 
-  switch (m_log_mode) {
-  case MTR_LOG_NONE:
-  case MTR_LOG_NO_REDO:
-    return true;
-  case MTR_LOG_ALL:
-    return m_user_space == space || is_predefined_tablespace(space->id);
-  }
-
-  ut_error;
-  return false;
+  return !is_logged() || m_user_space == space ||
+    is_predefined_tablespace(space->id);
 }
 #endif /* UNIV_DEBUG */
 
@@ -978,6 +961,68 @@ static mtr_t::page_flush_ahead log_close(lsn_t lsn)
   return mtr_t::PAGE_FLUSH_SYNC;
 }
 
+inline void mtr_t::page_checksum(const buf_page_t &bpage)
+{
+  const byte *page= bpage.frame;
+  size_t size= srv_page_size;
+
+  if (UNIV_LIKELY_NULL(bpage.zip.data))
+  {
+    size= (UNIV_ZIP_SIZE_MIN >> 1) << bpage.zip.ssize;
+    switch (fil_page_get_type(bpage.zip.data)) {
+    case FIL_PAGE_TYPE_ALLOCATED:
+    case FIL_PAGE_INODE:
+    case FIL_PAGE_IBUF_BITMAP:
+    case FIL_PAGE_TYPE_FSP_HDR:
+    case FIL_PAGE_TYPE_XDES:
+      /* These are essentially uncompressed pages. */
+      break;
+    default:
+      page= bpage.zip.data;
+    }
+  }
+
+  /* We have to exclude from the checksum the normal
+  page checksum that is written by buf_flush_init_for_writing()
+  and FIL_PAGE_LSN which would be updated once we have actually
+  allocated the LSN.
+
+  Unfortunately, we cannot access fil_space_t easily here. In order to
+  be compatible with encrypted tablespaces in the pre-full_crc32
+  format we will unconditionally exclude the 8 bytes at
+  FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION
+  a.k.a. FIL_RTREE_SPLIT_SEQ_NUM. */
+  const uint32_t checksum=
+    my_crc32c(my_crc32c(my_crc32c(0, page + FIL_PAGE_OFFSET,
+                                  FIL_PAGE_LSN - FIL_PAGE_OFFSET),
+                        page + FIL_PAGE_TYPE, 2),
+              page + FIL_PAGE_SPACE_ID, size - (FIL_PAGE_SPACE_ID + 8));
+
+  byte *l= log_write<OPTION>(bpage.id(), nullptr, 5, true, 0);
+  *l++= OPT_PAGE_CHECKSUM;
+  mach_write_to_4(l, checksum);
+  m_log.close(l + 4);
+}
+
+/** Write OPT_PAGE_CHECKSUM records for modified pages */
+struct WriteOPT_PAGE_CHECKSUM
+{
+  mtr_t &mtr;
+  WriteOPT_PAGE_CHECKSUM(mtr_t &mtr) : mtr(mtr) {}
+
+  /** @return true always */
+  bool operator()(const mtr_memo_slot_t *slot) const
+  {
+    if (slot->type & MTR_MEMO_MODIFY)
+    {
+      const buf_page_t &b= static_cast<const buf_block_t*>(slot->object)->page;
+      if (!b.is_freed())
+        mtr.page_checksum(b);
+    }
+    return true;
+  }
+};
+
 /** Write the block contents to the REDO log */
 struct mtr_write_log
 {
@@ -993,11 +1038,18 @@ struct mtr_write_log
 std::pair<lsn_t,mtr_t::page_flush_ahead> mtr_t::do_write()
 {
 	ut_ad(!recv_no_log_write);
-	ut_ad(m_log_mode == MTR_LOG_ALL);
+	ut_ad(is_logged());
 
 	ulint	len	= m_log.size();
 	ut_ad(len > 0);
 
+#ifdef UNIV_DEBUG
+	if (m_log_mode == MTR_LOG_ALL) {
+		m_memo.for_each_block(CIterate<WriteOPT_PAGE_CHECKSUM>(*this));
+		len = m_log.size();
+	}
+#endif
+
 	if (len > srv_log_buffer_size / 2) {
 		log_buffer_extend(ulong((len + 1) * 2));
 	}
@@ -1033,7 +1085,7 @@ std::pair<lsn_t,mtr_t::page_flush_ahead> mtr_t::do_write()
 @return {start_lsn,flush_ahead} */
 inline std::pair<lsn_t,mtr_t::page_flush_ahead> mtr_t::finish_write(ulint len)
 {
-	ut_ad(m_log_mode == MTR_LOG_ALL);
+	ut_ad(is_logged());
 	mysql_mutex_assert_owner(&log_sys.mutex);
 	ut_ad(m_log.size() == len);
 	ut_ad(len > 0);
@@ -1074,7 +1126,7 @@ struct FindBlockX
   /** @return whether the block was not found x-latched */
   bool operator()(const mtr_memo_slot_t *slot) const
   {
-    return slot->object != &block || slot->type != MTR_MEMO_PAGE_X_FIX;
+    return slot->object != &block || !(slot->type & MTR_MEMO_PAGE_X_FIX);
   }
 };
 
@@ -1381,7 +1433,7 @@ mtr_t::memo_contains_page_flagged(
 #endif /* UNIV_DEBUG */
 
 
-/** Find a block, preferrably in MTR_MEMO_MODIFY state */
+/** Find a potentially modified block. */
 struct FindModified
 {
   mtr_memo_slot_t *found= nullptr;
@@ -1393,8 +1445,7 @@ struct FindModified
     if (slot->object != &block)
       return true;
     found= slot;
-    return !(slot->type & (MTR_MEMO_MODIFY |
-                           MTR_MEMO_PAGE_X_FIX | MTR_MEMO_PAGE_SX_FIX));
+    return !(slot->type & (MTR_MEMO_PAGE_X_FIX | MTR_MEMO_PAGE_SX_FIX));
   }
 };
 
@@ -1420,3 +1471,63 @@ void mtr_t::modify(const buf_block_t &block)
   if (is_block_dirtied(&block))
     m_made_dirty= true;
 }
+
+/** Handle an exclusively latched block that was later marked as freed. */
+struct MarkFreed
+{
+  const page_id_t id;
+  mutable buf_block_t *freed= nullptr;
+  MarkFreed(page_id_t id) : id(id) {}
+
+  bool operator()(mtr_memo_slot_t *slot) const
+  {
+    buf_block_t *block= static_cast<buf_block_t*>(slot->object);
+    if (!block);
+    else if (block == freed)
+    {
+      if (slot->type & (MTR_MEMO_PAGE_SX_FIX | MTR_MEMO_PAGE_X_FIX))
+        slot->type= MTR_MEMO_PAGE_X_FIX;
+      else
+      {
+        ut_ad(slot->type == MTR_MEMO_BUF_FIX);
+        block->page.unfix();
+        slot->object= nullptr;
+      }
+    }
+    else if (slot->type & (MTR_MEMO_PAGE_X_FIX | MTR_MEMO_PAGE_SX_FIX) &&
+             block->page.id() == id)
+    {
+      ut_ad(!block->page.is_freed());
+      ut_ad(!freed);
+      freed= block;
+      if (!(slot->type & MTR_MEMO_PAGE_X_FIX))
+      {
+        ut_d(bool upgraded=) block->page.lock.x_lock_upgraded();
+        ut_ad(upgraded);
+      }
+      slot->type= MTR_MEMO_PAGE_X_MODIFY;
+#ifdef BTR_CUR_HASH_ADAPT
+      if (block->index)
+        btr_search_drop_page_hash_index(block);
+#endif /* BTR_CUR_HASH_ADAPT */
+      block->page.set_freed(block->page.state());
+    }
+    return true;
+  }
+};
+
+/** Free a page.
+@param space   tablespace
+@param offset  offset of the page to be freed */
+void mtr_t::free(const fil_space_t &space, uint32_t offset)
+{
+  ut_ad(is_named_space(&space));
+  ut_ad(!m_freed_space || m_freed_space == &space);
+
+  if (is_logged())
+  {
+    m_memo.for_each_block_in_reverse
+      (CIterate<MarkFreed>((MarkFreed{{space.id, offset}})));
+    m_log.close(log_write<FREE_PAGE>({space.id, offset}, nullptr));
+  }
+}
diff --git a/storage/innobase/page/page0cur.cc b/storage/innobase/page/page0cur.cc
index 2c9e2f5572a..bd0905e80dc 100644
--- a/storage/innobase/page/page0cur.cc
+++ b/storage/innobase/page/page0cur.cc
@@ -1309,7 +1309,7 @@ page_cur_insert_rec_low(
   ut_ad(!page_rec_is_supremum(cur->rec));
 
   /* We should not write log for ROW_FORMAT=COMPRESSED pages here. */
-  ut_ad(mtr->get_log_mode() != MTR_LOG_ALL ||
+  ut_ad(!mtr->is_logged() ||
         !(index->table->flags & DICT_TF_MASK_ZIP_SSIZE));
 
   /* 1. Get the size of the physical record in the page */
@@ -1509,7 +1509,7 @@ inc_dir:
     }
     rec_set_bit_field_1(next_rec, n_owned + 1, REC_NEW_N_OWNED,
                         REC_N_OWNED_MASK, REC_N_OWNED_SHIFT);
-    if (mtr->get_log_mode() != MTR_LOG_ALL)
+    if (!mtr->is_logged())
     {
       mtr->set_modified(*block);
       goto copied;
@@ -1551,7 +1551,7 @@ inc_dir:
     }
     rec_set_bit_field_1(next_rec, n_owned + 1, REC_OLD_N_OWNED,
                         REC_N_OWNED_MASK, REC_N_OWNED_SHIFT);
-    if (mtr->get_log_mode() != MTR_LOG_ALL)
+    if (!mtr->is_logged())
     {
       mtr->set_modified(*block);
       goto copied;
@@ -1572,7 +1572,7 @@ inc_dir:
   }
 
   /* Insert the record, possibly copying from the preceding record. */
-  ut_ad(mtr->get_log_mode() == MTR_LOG_ALL);
+  ut_ad(mtr->is_logged());
 
   {
     const byte *r= rec;
diff --git a/storage/innobase/page/page0zip.cc b/storage/innobase/page/page0zip.cc
index 1fd5c3c146c..7b603bb876b 100644
--- a/storage/innobase/page/page0zip.cc
+++ b/storage/innobase/page/page0zip.cc
@@ -411,12 +411,8 @@ static void page_zip_compress_write_log(buf_block_t *block,
 {
   ut_ad(!index->is_ibuf());
 
-  if (mtr->get_log_mode() != MTR_LOG_ALL)
-  {
-    ut_ad(mtr->get_log_mode() == MTR_LOG_NONE ||
-          mtr->get_log_mode() == MTR_LOG_NO_REDO);
+  if (!mtr->is_logged())
     return;
-  }
 
   const page_t *page= block->page.frame;
   const page_zip_des_t *page_zip= &block->page.zip;