diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index aeda826..8501dd2 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -8394,6 +8394,29 @@ LOG: CleanUpLock: deleting: lock(0xb7acd844) id(24688,24696,0,0,0,1)
+
+ ignore_slru_checksum_failure (boolean)
+
+ ignore_slru_checksum_failure configuration parameter
+
+
+
+
+ Only has effect if are enabled.
+
+
+ Detection of a checksum failure during a read normally causes
+ PostgreSQL to report an error. Setting ignore_slru_checksum_failure
+ to on causes the system to ignore the failure (but still report a warning), and
+ continue processing. Similary like ignore_checksum_failure but for
+ not relation files. The default setting is true, and it can only be
+ changed by a superuser. For changes, use ALTER SYSTEM and reload configuration:
+ ALTER SYSTEM SET ignore_slru_checksum_failure = off;
+ SELECT pg_reload_conf();
+
+
+
+
zero_damaged_pages (boolean)
diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index a3e2b12..87ed09c 100644
--- a/src/backend/access/transam/clog.c
+++ b/src/backend/access/transam/clog.c
@@ -58,7 +58,7 @@
/* We need two bits per xact, so four xacts fit in a byte */
#define CLOG_BITS_PER_XACT 2
#define CLOG_XACTS_PER_BYTE 4
-#define CLOG_XACTS_PER_PAGE (BLCKSZ * CLOG_XACTS_PER_BYTE)
+#define CLOG_XACTS_PER_PAGE ((BLCKSZ - CHKSUMSZ) * CLOG_XACTS_PER_BYTE)
#define CLOG_XACT_BITMASK ((1 << CLOG_BITS_PER_XACT) - 1)
#define TransactionIdToPage(xid) ((xid) / (TransactionId) CLOG_XACTS_PER_PAGE)
diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c
index 7142ece..35c317e 100644
--- a/src/backend/access/transam/multixact.c
+++ b/src/backend/access/transam/multixact.c
@@ -106,7 +106,7 @@
*/
/* We need four bytes per offset */
-#define MULTIXACT_OFFSETS_PER_PAGE (BLCKSZ / sizeof(MultiXactOffset))
+#define MULTIXACT_OFFSETS_PER_PAGE ((BLCKSZ - CHKSUMSZ) / sizeof(MultiXactOffset))
#define MultiXactIdToOffsetPage(xid) \
((xid) / (MultiXactOffset) MULTIXACT_OFFSETS_PER_PAGE)
@@ -2039,7 +2039,6 @@ TrimMultiXact(void)
{
int slotno;
MultiXactOffset *offptr;
-
slotno = SimpleLruReadPage(MultiXactOffsetCtl, pageno, true, nextMXact);
offptr = (MultiXactOffset *) MultiXactOffsetCtl->shared->page_buffer[slotno];
offptr += entryno;
diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c
index 9dd7719..b7a154c 100644
--- a/src/backend/access/transam/slru.c
+++ b/src/backend/access/transam/slru.c
@@ -58,7 +58,18 @@
#include "storage/fd.h"
#include "storage/shmem.h"
#include "miscadmin.h"
+#include "utils/guc.h"
+#include "storage/checksum.h"
+#include "utils/memutils.h"
+
+/*
+ * GUC variable
+ * Set from backend:
+ * alter system set ignore_slru_checksum_failure = on/off;
+ * select pg_reload_conf();
+ */
+bool ignore_slru_checksum_failure = true;
#define SlruFileName(ctl, path, seg) \
snprintf(path, MAXPGPATH, "%s/%04X", (ctl)->Dir, seg)
@@ -376,6 +387,8 @@ SimpleLruReadPage(SlruCtl ctl, int pageno, bool write_ok,
TransactionId xid)
{
SlruShared shared = ctl->shared;
+ int checksum;
+ static char *pageCopy = NULL;
/* Outer loop handles restart if we must wait for someone else's I/O */
for (;;)
@@ -426,6 +439,22 @@ SimpleLruReadPage(SlruCtl ctl, int pageno, bool write_ok,
/* Do the read */
ok = SlruPhysicalReadPage(ctl, pageno, slotno);
+ if (pageCopy == NULL)
+ pageCopy = MemoryContextAlloc(TopMemoryContext, BLCKSZ);
+
+ memcpy(pageCopy, shared->page_buffer[slotno], BLCKSZ);
+
+ checksum = pg_getchecksum_slru_page(pageCopy);
+
+ if ( DataChecksumsEnabled() && (checksum != pg_checksum_slru_page(pageCopy) ))
+ {
+ elog(LOG, "CHECKSUM: Page Is not Verified.");
+ if (!ignore_slru_checksum_failure)
+ {
+ elog(ERROR, "CHECKSUM: ERROR ignore_slru_checksum_failure turned off.");
+ }
+ }
+
/* Set the LSNs for this newly read-in page to zero */
SimpleLruZeroLSNs(ctl, slotno);
@@ -539,6 +568,14 @@ SlruInternalWritePage(SlruCtl ctl, int slotno, SlruFlush fdata)
/* Release control lock while doing I/O */
LWLockRelease(shared->ControlLock);
+ /*
+ * Calculate checksum of the page and write in the last 2 bytes of the page
+ *
+ * NOTE: it`s all done in checksum_impl.h : pg_checksum_slru_page()
+ * you give there page and get page with updated checksum
+ */
+ pg_checksum_slru_page(shared->page_buffer[slotno]);
+
/* Do the write */
ok = SlruPhysicalWritePage(ctl, pageno, slotno, fdata);
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index ae22185..8d62e7e 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -116,6 +116,7 @@ extern int CommitSiblings;
extern char *default_tablespace;
extern char *temp_tablespaces;
extern bool ignore_checksum_failure;
+extern bool ignore_slru_checksum_failure;
extern bool synchronize_seqscans;
#ifdef TRACE_SYNCSCAN
@@ -1006,6 +1007,20 @@ static struct config_bool ConfigureNamesBool[] =
NULL, NULL, NULL
},
{
+ {"ignore_slru_checksum_failure", PGC_SUSET, DEVELOPER_OPTIONS,
+ gettext_noop("Continues processing after SLRU checksum failure."),
+ gettext_noop("Detection of a SLRU checksum failure normally causes PostgreSQL to "
+ "report an error. Setting ignore_slru_checksum_failure to true"
+ "causes the system to ignore the failure (but still report a warning), and"
+ "continue processing. This behavior could cause crashes or other serious"
+ "problems. Only has an effect if checksums are enabled."),
+ GUC_NOT_IN_SAMPLE
+ },
+ &ignore_slru_checksum_failure,
+ true,
+ NULL, NULL, NULL
+ },
+ {
{"zero_damaged_pages", PGC_SUSET, DEVELOPER_OPTIONS,
gettext_noop("Continues processing past damaged page headers."),
gettext_noop("Detection of a damaged page header normally causes PostgreSQL to "
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 0f2b8bd..57f7a1e 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -292,6 +292,9 @@ extern void assign_checkpoint_completion_target(double newval, void *extra);
* Routines to start, stop, and get status of a base backup.
*/
+/* Size of checksum in bytes default 2 bytes (uint16) */
+#define CHKSUMSZ 2
+
/*
* Session-level status of base backups
*
diff --git a/src/include/storage/checksum.h b/src/include/storage/checksum.h
index b85f714..67535b0 100644
--- a/src/include/storage/checksum.h
+++ b/src/include/storage/checksum.h
@@ -21,4 +21,8 @@
*/
extern uint16 pg_checksum_page(char *page, BlockNumber blkno);
+extern uint16 pg_checksum_slru_page(char *page);
+
+extern uint16 pg_getchecksum_slru_page(char *page);
+
#endif /* CHECKSUM_H */
diff --git a/src/include/storage/checksum_impl.h b/src/include/storage/checksum_impl.h
index bffd061..8e340db 100644
--- a/src/include/storage/checksum_impl.h
+++ b/src/include/storage/checksum_impl.h
@@ -106,6 +106,8 @@
#define N_SUMS 32
/* prime multiplier of FNV-1a hash */
#define FNV_PRIME 16777619
+/* Size of checksum in bytes default 2 bytes (uint16) */
+#define CHKSUMSZ 2
/*
* Base offsets to initialize each of the parallel FNV hashes into a
@@ -205,3 +207,51 @@ pg_checksum_page(char *page, BlockNumber blkno)
*/
return (checksum % 65535) + 1;
}
+
+/*
+ * Compute the checksum for a Postgres SLRU page. The page must be aligned on a
+ * 4-byte boundary.
+ *
+ * The checksum save itself to the last 2 bytes (CHKSUMSZ = 2 bytes) of the page
+ */
+uint16
+pg_checksum_slru_page(char *page)
+{
+ uint16 checksum;
+ uint8 bytes[2];
+
+ /* Set last 2 bytes to 0 */
+ page[BLCKSZ - 1] = 0;
+ page[BLCKSZ - 2] = 0;
+
+ checksum = (pg_checksum_block(page, BLCKSZ) % 65535) + 1;
+
+ bytes[0] = (checksum & 0X00FF); /* Least significant bit */
+ bytes[1] = (checksum & 0XFF00) >> 8; /* Most significant bit */
+
+
+ /* Set last 2 bytes to calculated checksum */
+ page[BLCKSZ - 1] = bytes[0];
+ page[BLCKSZ - 2] = bytes[1];
+
+ return checksum;
+}
+
+
+/*
+ * Get the checksum for a Postgres SLRU page. The page must be aligned on a
+ * 4-byte boundary.
+ *
+ * The checksum located at last 2 bytes (CHKSUMSZ = 2 bytes) of the page
+ */
+uint16
+pg_getchecksum_slru_page(char *page)
+{
+ uint16 checksum = 0X00000000;
+
+ checksum = checksum | page[BLCKSZ - 2];
+ checksum = checksum << 8 ;
+ checksum = checksum | (page[BLCKSZ - 1] & 0X00FF);
+
+ return checksum;
+}