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Commit0851e12

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Reorganize clog's error reporting so that PANIC on clog I/O error can
be reduced to a plain ERROR. Should make it at least a little lesspainful to deal with data-corruption problems.
1 parent6bfa2df commit0851e12

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1 file changed

+135
-30
lines changed
  • src/backend/access/transam

1 file changed

+135
-30
lines changed

‎src/backend/access/transam/clog.c‎

Lines changed: 135 additions & 30 deletions
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,7 @@
1313
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
1414
* Portions Copyright (c) 1994, Regents of the University of California
1515
*
16-
* $Header: /cvsroot/pgsql/src/backend/access/transam/clog.c,v 1.11 2002/09/26 22:58:33 tgl Exp $
16+
* $Header: /cvsroot/pgsql/src/backend/access/transam/clog.c,v 1.12 2003/04/14 17:31:33 tgl Exp $
1717
*
1818
*-------------------------------------------------------------------------
1919
*/
@@ -123,7 +123,7 @@ typedef enum
123123
CLOG_PAGE_READ_IN_PROGRESS,/* CLOG page is being read in */
124124
CLOG_PAGE_CLEAN,/* CLOG page is valid and not dirty */
125125
CLOG_PAGE_DIRTY,/* CLOG page is valid but needs write */
126-
CLOG_PAGE_WRITE_IN_PROGRESS/* CLOG page is being written outin*/
126+
CLOG_PAGE_WRITE_IN_PROGRESS/* CLOG page is being written out */
127127
}ClogPageStatus;
128128

129129
/*
@@ -180,12 +180,25 @@ static char ClogDir[MAXPGPATH];
180180
ClogCtl->page_lru_count[slotno] = 0; \
181181
} while (0)
182182

183+
/* Saved info for CLOGReportIOError */
184+
typedefenum
185+
{
186+
CLOG_OPEN_FAILED,
187+
CLOG_CREATE_FAILED,
188+
CLOG_SEEK_FAILED,
189+
CLOG_READ_FAILED,
190+
CLOG_WRITE_FAILED
191+
}ClogErrorCause;
192+
staticClogErrorCauseclog_errcause;
193+
staticintclog_errno;
194+
183195

184196
staticintZeroCLOGPage(intpageno,boolwriteXlog);
185-
staticintReadCLOGPage(intpageno);
197+
staticintReadCLOGPage(intpageno,TransactionIdxid);
186198
staticvoidWriteCLOGPage(intslotno);
187-
staticvoidCLOGPhysicalReadPage(intpageno,intslotno);
188-
staticvoidCLOGPhysicalWritePage(intpageno,intslotno);
199+
staticboolCLOGPhysicalReadPage(intpageno,intslotno);
200+
staticboolCLOGPhysicalWritePage(intpageno,intslotno);
201+
staticvoidCLOGReportIOError(intpageno,TransactionIdxid);
189202
staticintSelectLRUCLOGPage(intpageno);
190203
staticboolScanCLOGDirectory(intcutoffPage,booldoDeletions);
191204
staticboolCLOGPagePrecedes(intpage1,intpage2);
@@ -212,7 +225,7 @@ TransactionIdSetStatus(TransactionId xid, XidStatus status)
212225

213226
LWLockAcquire(CLogControlLock,LW_EXCLUSIVE);
214227

215-
slotno=ReadCLOGPage(pageno);
228+
slotno=ReadCLOGPage(pageno,xid);
216229
byteptr=ClogCtl->page_buffer[slotno]+byteno;
217230

218231
/* Current state should be 0 or target state */
@@ -244,7 +257,7 @@ TransactionIdGetStatus(TransactionId xid)
244257

245258
LWLockAcquire(CLogControlLock,LW_EXCLUSIVE);
246259

247-
slotno=ReadCLOGPage(pageno);
260+
slotno=ReadCLOGPage(pageno,xid);
248261
byteptr=ClogCtl->page_buffer[slotno]+byteno;
249262

250263
status= (*byteptr >>bshift)&CLOG_XACT_BITMASK;
@@ -362,18 +375,22 @@ ZeroCLOGPage(int pageno, bool writeXlog)
362375
* Find a CLOG page in a shared buffer, reading it in if necessary.
363376
* The page number must correspond to an already-initialized page.
364377
*
378+
* The passed-in xid is used only for error reporting, and may be
379+
* InvalidTransactionId if no specific xid is associated with the action.
380+
*
365381
* Return value is the shared-buffer slot number now holding the page.
366382
* The buffer's LRU access info is updated.
367383
*
368384
* Control lock must be held at entry, and will be held at exit.
369385
*/
370386
staticint
371-
ReadCLOGPage(intpageno)
387+
ReadCLOGPage(intpageno,TransactionIdxid)
372388
{
373389
/* Outer loop handles restart if we lose the buffer to someone else */
374390
for (;;)
375391
{
376392
intslotno;
393+
boolok;
377394

378395
/* See if page already is in memory; if not, pick victim slot */
379396
slotno=SelectLRUCLOGPage(pageno);
@@ -424,18 +441,22 @@ ReadCLOGPage(int pageno)
424441
}
425442

426443
/* Okay, do the read */
427-
CLOGPhysicalReadPage(pageno,slotno);
444+
ok=CLOGPhysicalReadPage(pageno,slotno);
428445

429446
/* Re-acquire shared control lock and update page state */
430447
LWLockAcquire(CLogControlLock,LW_EXCLUSIVE);
431448

432449
Assert(ClogCtl->page_number[slotno]==pageno&&
433450
ClogCtl->page_status[slotno]==CLOG_PAGE_READ_IN_PROGRESS);
434451

435-
ClogCtl->page_status[slotno]=CLOG_PAGE_CLEAN;
452+
ClogCtl->page_status[slotno]=ok ?CLOG_PAGE_CLEAN :CLOG_PAGE_EMPTY;
436453

437454
LWLockRelease(ClogBufferLocks[slotno]);
438455

456+
/* Now it's okay to elog if we failed */
457+
if (!ok)
458+
CLOGReportIOError(pageno,xid);
459+
439460
ClogRecentlyUsed(slotno);
440461
returnslotno;
441462
}
@@ -456,6 +477,7 @@ static void
456477
WriteCLOGPage(intslotno)
457478
{
458479
intpageno;
480+
boolok;
459481

460482
/* Do nothing if page does not need writing */
461483
if (ClogCtl->page_status[slotno]!=CLOG_PAGE_DIRTY&&
@@ -499,7 +521,7 @@ WriteCLOGPage(int slotno)
499521
ClogCtl->page_status[slotno]=CLOG_PAGE_WRITE_IN_PROGRESS;
500522

501523
/* Okay, do the write */
502-
CLOGPhysicalWritePage(pageno,slotno);
524+
ok=CLOGPhysicalWritePage(pageno,slotno);
503525

504526
/* Re-acquire shared control lock and update page state */
505527
LWLockAcquire(CLogControlLock,LW_EXCLUSIVE);
@@ -510,18 +532,26 @@ WriteCLOGPage(int slotno)
510532

511533
/* Cannot set CLEAN if someone re-dirtied page since write started */
512534
if (ClogCtl->page_status[slotno]==CLOG_PAGE_WRITE_IN_PROGRESS)
513-
ClogCtl->page_status[slotno]=CLOG_PAGE_CLEAN;
535+
ClogCtl->page_status[slotno]=ok ?CLOG_PAGE_CLEAN :CLOG_PAGE_DIRTY;
514536

515537
LWLockRelease(ClogBufferLocks[slotno]);
538+
539+
/* Now it's okay to elog if we failed */
540+
if (!ok)
541+
CLOGReportIOError(pageno,InvalidTransactionId);
516542
}
517543

518544
/*
519545
* Physical read of a (previously existing) page into a buffer slot
520546
*
547+
* On failure, we cannot just elog(ERROR) since caller has put state in
548+
* shared memory that must be undone. So, we return FALSE and save enough
549+
* info in static variables to let CLOGReportIOError make the report.
550+
*
521551
* For now, assume it's not worth keeping a file pointer open across
522552
* read/write operations. We could cache one virtual file pointer ...
523553
*/
524-
staticvoid
554+
staticbool
525555
CLOGPhysicalReadPage(intpageno,intslotno)
526556
{
527557
intsegno=pageno /CLOG_PAGES_PER_SEGMENT;
@@ -543,31 +573,47 @@ CLOGPhysicalReadPage(int pageno, int slotno)
543573
if (fd<0)
544574
{
545575
if (errno!=ENOENT|| !InRecovery)
546-
elog(PANIC,"open of %s failed: %m",path);
576+
{
577+
clog_errcause=CLOG_OPEN_FAILED;
578+
clog_errno=errno;
579+
return false;
580+
}
581+
547582
elog(LOG,"clog file %s doesn't exist, reading as zeroes",path);
548583
MemSet(ClogCtl->page_buffer[slotno],0,CLOG_BLCKSZ);
549-
return;
584+
return true;
550585
}
551586

552587
if (lseek(fd, (off_t)offset,SEEK_SET)<0)
553-
elog(PANIC,"lseek of clog file %u, offset %u failed: %m",
554-
segno,offset);
588+
{
589+
clog_errcause=CLOG_SEEK_FAILED;
590+
clog_errno=errno;
591+
return false;
592+
}
555593

556594
errno=0;
557595
if (read(fd,ClogCtl->page_buffer[slotno],CLOG_BLCKSZ)!=CLOG_BLCKSZ)
558-
elog(PANIC,"read of clog file %u, offset %u failed: %m",
559-
segno,offset);
596+
{
597+
clog_errcause=CLOG_READ_FAILED;
598+
clog_errno=errno;
599+
return false;
600+
}
560601

561602
close(fd);
603+
return true;
562604
}
563605

564606
/*
565607
* Physical write of a page from a buffer slot
566608
*
609+
* On failure, we cannot just elog(ERROR) since caller has put state in
610+
* shared memory that must be undone. So, we return FALSE and save enough
611+
* info in static variables to let CLOGReportIOError make the report.
612+
*
567613
* For now, assume it's not worth keeping a file pointer open across
568614
* read/write operations. We could cache one virtual file pointer ...
569615
*/
570-
staticvoid
616+
staticbool
571617
CLOGPhysicalWritePage(intpageno,intslotno)
572618
{
573619
intsegno=pageno /CLOG_PAGES_PER_SEGMENT;
@@ -595,28 +641,85 @@ CLOGPhysicalWritePage(int pageno, int slotno)
595641
if (fd<0)
596642
{
597643
if (errno!=ENOENT)
598-
elog(PANIC,"open of %s failed: %m",path);
644+
{
645+
clog_errcause=CLOG_OPEN_FAILED;
646+
clog_errno=errno;
647+
return false;
648+
}
649+
599650
fd=BasicOpenFile(path,O_RDWR |O_CREAT |O_EXCL |PG_BINARY,
600651
S_IRUSR |S_IWUSR);
601652
if (fd<0)
602-
elog(PANIC,"creation of file %s failed: %m",path);
653+
{
654+
clog_errcause=CLOG_CREATE_FAILED;
655+
clog_errno=errno;
656+
return false;
657+
}
603658
}
604659

605660
if (lseek(fd, (off_t)offset,SEEK_SET)<0)
606-
elog(PANIC,"lseek of clog file %u, offset %u failed: %m",
607-
segno,offset);
661+
{
662+
clog_errcause=CLOG_SEEK_FAILED;
663+
clog_errno=errno;
664+
return false;
665+
}
608666

609667
errno=0;
610668
if (write(fd,ClogCtl->page_buffer[slotno],CLOG_BLCKSZ)!=CLOG_BLCKSZ)
611669
{
612670
/* if write didn't set errno, assume problem is no disk space */
613671
if (errno==0)
614672
errno=ENOSPC;
615-
elog(PANIC,"write of clog file %u, offset %u failed: %m",
616-
segno,offset);
673+
clog_errcause=CLOG_WRITE_FAILED;
674+
clog_errno=errno;
675+
return false;
617676
}
618677

619678
close(fd);
679+
return true;
680+
}
681+
682+
/*
683+
* Issue the error message after failure of CLOGPhysicalReadPage or
684+
* CLOGPhysicalWritePage. Call this after cleaning up shared-memory state.
685+
*/
686+
staticvoid
687+
CLOGReportIOError(intpageno,TransactionIdxid)
688+
{
689+
intsegno=pageno /CLOG_PAGES_PER_SEGMENT;
690+
intrpageno=pageno %CLOG_PAGES_PER_SEGMENT;
691+
intoffset=rpageno*CLOG_BLCKSZ;
692+
charpath[MAXPGPATH];
693+
694+
/* XXX TODO: provide xid as context in error messages */
695+
696+
ClogFileName(path,segno);
697+
errno=clog_errno;
698+
switch (clog_errcause)
699+
{
700+
caseCLOG_OPEN_FAILED:
701+
elog(ERROR,"open of %s failed: %m",path);
702+
break;
703+
caseCLOG_CREATE_FAILED:
704+
elog(ERROR,"creation of file %s failed: %m",path);
705+
break;
706+
caseCLOG_SEEK_FAILED:
707+
elog(ERROR,"lseek of clog file %u, offset %u failed: %m",
708+
segno,offset);
709+
break;
710+
caseCLOG_READ_FAILED:
711+
elog(ERROR,"read of clog file %u, offset %u failed: %m",
712+
segno,offset);
713+
break;
714+
caseCLOG_WRITE_FAILED:
715+
elog(ERROR,"write of clog file %u, offset %u failed: %m",
716+
segno,offset);
717+
break;
718+
default:
719+
/* can't get here, we trust */
720+
elog(ERROR,"unknown CLOG I/O error");
721+
break;
722+
}
620723
}
621724

622725
/*
@@ -679,7 +782,8 @@ SelectLRUCLOGPage(int pageno)
679782
* the read to complete.
680783
*/
681784
if (ClogCtl->page_status[bestslot]==CLOG_PAGE_READ_IN_PROGRESS)
682-
(void)ReadCLOGPage(ClogCtl->page_number[bestslot]);
785+
(void)ReadCLOGPage(ClogCtl->page_number[bestslot],
786+
InvalidTransactionId);
683787
else
684788
WriteCLOGPage(bestslot);
685789

@@ -857,7 +961,8 @@ restart:;
857961
* This is the same logic as in SelectLRUCLOGPage.
858962
*/
859963
if (ClogCtl->page_status[slotno]==CLOG_PAGE_READ_IN_PROGRESS)
860-
(void)ReadCLOGPage(ClogCtl->page_number[slotno]);
964+
(void)ReadCLOGPage(ClogCtl->page_number[slotno],
965+
InvalidTransactionId);
861966
else
862967
WriteCLOGPage(slotno);
863968
gotorestart;
@@ -886,7 +991,7 @@ ScanCLOGDirectory(int cutoffPage, bool doDeletions)
886991

887992
cldir=opendir(ClogDir);
888993
if (cldir==NULL)
889-
elog(PANIC,"could not open transaction-commit log directory (%s): %m",
994+
elog(ERROR,"could not open transaction-commit log directory (%s): %m",
890995
ClogDir);
891996

892997
errno=0;
@@ -911,7 +1016,7 @@ ScanCLOGDirectory(int cutoffPage, bool doDeletions)
9111016
errno=0;
9121017
}
9131018
if (errno)
914-
elog(PANIC,"could not read transaction-commit log directory (%s): %m",
1019+
elog(ERROR,"could not read transaction-commit log directory (%s): %m",
9151020
ClogDir);
9161021
closedir(cldir);
9171022

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