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Replace RelationOpenSmgr() with RelationGetSmgr().
The idea behind this patch is to design out bugs like the one fixed by commit 9d52311. Previously, once one did RelationOpenSmgr(rel), it was considered okay to access rel->rd_smgr directly for some not-very-clear interval. But since that pointer will be cleared by relcache flushes, we had bugs arising from overreliance on a previous RelationOpenSmgr call still being effective. Now, very little code except that in rel.h and relcache.c should ever touch the rd_smgr field directly. The normal coding rule is to use RelationGetSmgr(rel) and not expect the result to be valid for longer than one smgr function call. There are a couple of places where using the function every single time seemed like overkill, but they are now annotated with large warning comments. Amul Sul, after an idea of mine. Discussion: https://postgr.es/m/CANiYTQsU7yMFpQYnv=BrcRVqK_3U3mtAzAsJCaqtzsDHfsUbdQ@mail.gmail.com
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21 files changed

+165
-166
lines changed

21 files changed

+165
-166
lines changed

‎contrib/amcheck/verify_nbtree.c‎

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -301,8 +301,7 @@ bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
301301
bool heapkeyspace,
302302
allequalimage;
303303

304-
RelationOpenSmgr(indrel);
305-
if (!smgrexists(indrel->rd_smgr, MAIN_FORKNUM))
304+
if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
306305
ereport(ERROR,
307306
(errcode(ERRCODE_INDEX_CORRUPTED),
308307
errmsg("index \"%s\" lacks a main relation fork",

‎contrib/bloom/blinsert.c‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -177,17 +177,17 @@ blbuildempty(Relation index)
177177
* this even when wal_level=minimal.
178178
*/
179179
PageSetChecksumInplace(metapage, BLOOM_METAPAGE_BLKNO);
180-
smgrwrite(index->rd_smgr, INIT_FORKNUM, BLOOM_METAPAGE_BLKNO,
180+
smgrwrite(RelationGetSmgr(index), INIT_FORKNUM, BLOOM_METAPAGE_BLKNO,
181181
(char *) metapage, true);
182-
log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM,
182+
log_newpage(&(RelationGetSmgr(index))->smgr_rnode.node, INIT_FORKNUM,
183183
BLOOM_METAPAGE_BLKNO, metapage, true);
184184

185185
/*
186186
* An immediate sync is required even if we xlog'd the page, because the
187187
* write did not go through shared_buffers and therefore a concurrent
188188
* checkpoint may have moved the redo pointer past our xlog record.
189189
*/
190-
smgrimmedsync(index->rd_smgr, INIT_FORKNUM);
190+
smgrimmedsync(RelationGetSmgr(index), INIT_FORKNUM);
191191
}
192192

193193
/*

‎contrib/pg_prewarm/autoprewarm.c‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -514,15 +514,13 @@ autoprewarm_database_main(Datum main_arg)
514514
old_blk->filenode != blk->filenode ||
515515
old_blk->forknum != blk->forknum)
516516
{
517-
RelationOpenSmgr(rel);
518-
519517
/*
520518
* smgrexists is not safe for illegal forknum, hence check whether
521519
* the passed forknum is valid before using it in smgrexists.
522520
*/
523521
if (blk->forknum > InvalidForkNumber &&
524522
blk->forknum <= MAX_FORKNUM &&
525-
smgrexists(rel->rd_smgr, blk->forknum))
523+
smgrexists(RelationGetSmgr(rel), blk->forknum))
526524
nblocks = RelationGetNumberOfBlocksInFork(rel, blk->forknum);
527525
else
528526
nblocks = 0;

‎contrib/pg_prewarm/pg_prewarm.c‎

Lines changed: 2 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -109,8 +109,7 @@ pg_prewarm(PG_FUNCTION_ARGS)
109109
aclcheck_error(aclresult, get_relkind_objtype(rel->rd_rel->relkind), get_rel_name(relOid));
110110

111111
/* Check that the fork exists. */
112-
RelationOpenSmgr(rel);
113-
if (!smgrexists(rel->rd_smgr, forkNumber))
112+
if (!smgrexists(RelationGetSmgr(rel), forkNumber))
114113
ereport(ERROR,
115114
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
116115
errmsg("fork \"%s\" does not exist for this relation",
@@ -178,7 +177,7 @@ pg_prewarm(PG_FUNCTION_ARGS)
178177
for (block = first_block; block <= last_block; ++block)
179178
{
180179
CHECK_FOR_INTERRUPTS();
181-
smgrread(rel->rd_smgr, forkNumber, block, blockbuffer.data);
180+
smgrread(RelationGetSmgr(rel), forkNumber, block, blockbuffer.data);
182181
++blocks_done;
183182
}
184183
}

‎contrib/pg_visibility/pg_visibility.c‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -391,14 +391,14 @@ pg_truncate_visibility_map(PG_FUNCTION_ARGS)
391391
/* Only some relkinds have a visibility map */
392392
check_relation_relkind(rel);
393393

394-
RelationOpenSmgr(rel);
395-
rel->rd_smgr->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] = InvalidBlockNumber;
394+
/* Forcibly reset cached file size */
395+
RelationGetSmgr(rel)->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] = InvalidBlockNumber;
396396

397397
block = visibilitymap_prepare_truncate(rel, 0);
398398
if (BlockNumberIsValid(block))
399399
{
400400
fork = VISIBILITYMAP_FORKNUM;
401-
smgrtruncate(rel->rd_smgr, &fork, 1, &block);
401+
smgrtruncate(RelationGetSmgr(rel), &fork, 1, &block);
402402
}
403403

404404
if (RelationNeedsWAL(rel))

‎src/backend/access/gist/gistbuild.c‎

Lines changed: 6 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -409,8 +409,7 @@ gist_indexsortbuild(GISTBuildState *state)
409409
* replaced with the real root page at the end.
410410
*/
411411
page = palloc0(BLCKSZ);
412-
RelationOpenSmgr(state->indexrel);
413-
smgrextend(state->indexrel->rd_smgr, MAIN_FORKNUM, GIST_ROOT_BLKNO,
412+
smgrextend(RelationGetSmgr(state->indexrel), MAIN_FORKNUM, GIST_ROOT_BLKNO,
414413
page, true);
415414
state->pages_allocated++;
416415
state->pages_written++;
@@ -450,10 +449,9 @@ gist_indexsortbuild(GISTBuildState *state)
450449
gist_indexsortbuild_flush_ready_pages(state);
451450

452451
/* Write out the root */
453-
RelationOpenSmgr(state->indexrel);
454452
PageSetLSN(pagestate->page, GistBuildLSN);
455453
PageSetChecksumInplace(pagestate->page, GIST_ROOT_BLKNO);
456-
smgrwrite(state->indexrel->rd_smgr, MAIN_FORKNUM, GIST_ROOT_BLKNO,
454+
smgrwrite(RelationGetSmgr(state->indexrel), MAIN_FORKNUM, GIST_ROOT_BLKNO,
457455
pagestate->page, true);
458456
if (RelationNeedsWAL(state->indexrel))
459457
log_newpage(&state->indexrel->rd_node, MAIN_FORKNUM, GIST_ROOT_BLKNO,
@@ -562,8 +560,6 @@ gist_indexsortbuild_flush_ready_pages(GISTBuildState *state)
562560
if (state->ready_num_pages == 0)
563561
return;
564562

565-
RelationOpenSmgr(state->indexrel);
566-
567563
for (int i = 0; i < state->ready_num_pages; i++)
568564
{
569565
Page page = state->ready_pages[i];
@@ -575,7 +571,8 @@ gist_indexsortbuild_flush_ready_pages(GISTBuildState *state)
575571

576572
PageSetLSN(page, GistBuildLSN);
577573
PageSetChecksumInplace(page, blkno);
578-
smgrextend(state->indexrel->rd_smgr, MAIN_FORKNUM, blkno, page, true);
574+
smgrextend(RelationGetSmgr(state->indexrel), MAIN_FORKNUM, blkno, page,
575+
true);
579576

580577
state->pages_written++;
581578
}
@@ -860,7 +857,8 @@ gistBuildCallback(Relation index,
860857
*/
861858
if ((buildstate->buildMode == GIST_BUFFERING_AUTO &&
862859
buildstate->indtuples % BUFFERING_MODE_SWITCH_CHECK_STEP == 0 &&
863-
effective_cache_size < smgrnblocks(index->rd_smgr, MAIN_FORKNUM)) ||
860+
effective_cache_size < smgrnblocks(RelationGetSmgr(index),
861+
MAIN_FORKNUM)) ||
864862
(buildstate->buildMode == GIST_BUFFERING_STATS &&
865863
buildstate->indtuples >= BUFFERING_MODE_TUPLE_SIZE_STATS_TARGET))
866864
{

‎src/backend/access/hash/hashpage.c‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1024,9 +1024,9 @@ _hash_alloc_buckets(Relation rel, BlockNumber firstblock, uint32 nblocks)
10241024
zerobuf.data,
10251025
true);
10261026

1027-
RelationOpenSmgr(rel);
10281027
PageSetChecksumInplace(page, lastblock);
1029-
smgrextend(rel->rd_smgr, MAIN_FORKNUM, lastblock, zerobuf.data, false);
1028+
smgrextend(RelationGetSmgr(rel), MAIN_FORKNUM, lastblock, zerobuf.data,
1029+
false);
10301030

10311031
return true;
10321032
}

‎src/backend/access/heap/heapam_handler.c‎

Lines changed: 3 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -625,7 +625,6 @@ heapam_relation_copy_data(Relation rel, const RelFileNode *newrnode)
625625
SMgrRelation dstrel;
626626

627627
dstrel = smgropen(*newrnode, rel->rd_backend);
628-
RelationOpenSmgr(rel);
629628

630629
/*
631630
* Since we copy the file directly without looking at the shared buffers,
@@ -645,14 +644,14 @@ heapam_relation_copy_data(Relation rel, const RelFileNode *newrnode)
645644
RelationCreateStorage(*newrnode, rel->rd_rel->relpersistence);
646645

647646
/* copy main fork */
648-
RelationCopyStorage(rel->rd_smgr, dstrel, MAIN_FORKNUM,
647+
RelationCopyStorage(RelationGetSmgr(rel), dstrel, MAIN_FORKNUM,
649648
rel->rd_rel->relpersistence);
650649

651650
/* copy those extra forks that exist */
652651
for (ForkNumber forkNum = MAIN_FORKNUM + 1;
653652
forkNum <= MAX_FORKNUM; forkNum++)
654653
{
655-
if (smgrexists(rel->rd_smgr, forkNum))
654+
if (smgrexists(RelationGetSmgr(rel), forkNum))
656655
{
657656
smgrcreate(dstrel, forkNum, false);
658657

@@ -664,7 +663,7 @@ heapam_relation_copy_data(Relation rel, const RelFileNode *newrnode)
664663
(rel->rd_rel->relpersistence == RELPERSISTENCE_UNLOGGED &&
665664
forkNum == INIT_FORKNUM))
666665
log_smgrcreate(newrnode, forkNum);
667-
RelationCopyStorage(rel->rd_smgr, dstrel, forkNum,
666+
RelationCopyStorage(RelationGetSmgr(rel), dstrel, forkNum,
668667
rel->rd_rel->relpersistence);
669668
}
670669
}

‎src/backend/access/heap/rewriteheap.c‎

Lines changed: 4 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -326,9 +326,8 @@ end_heap_rewrite(RewriteState state)
326326

327327
PageSetChecksumInplace(state->rs_buffer, state->rs_blockno);
328328

329-
RelationOpenSmgr(state->rs_new_rel);
330-
smgrextend(state->rs_new_rel->rd_smgr, MAIN_FORKNUM, state->rs_blockno,
331-
(char *) state->rs_buffer, true);
329+
smgrextend(RelationGetSmgr(state->rs_new_rel), MAIN_FORKNUM,
330+
state->rs_blockno, (char *) state->rs_buffer, true);
332331
}
333332

334333
/*
@@ -339,11 +338,7 @@ end_heap_rewrite(RewriteState state)
339338
* wrote before the checkpoint.
340339
*/
341340
if (RelationNeedsWAL(state->rs_new_rel))
342-
{
343-
/* for an empty table, this could be first smgr access */
344-
RelationOpenSmgr(state->rs_new_rel);
345-
smgrimmedsync(state->rs_new_rel->rd_smgr, MAIN_FORKNUM);
346-
}
341+
smgrimmedsync(RelationGetSmgr(state->rs_new_rel), MAIN_FORKNUM);
347342

348343
logical_end_heap_rewrite(state);
349344

@@ -695,11 +690,9 @@ raw_heap_insert(RewriteState state, HeapTuple tup)
695690
* need for smgr to schedule an fsync for this write; we'll do it
696691
* ourselves in end_heap_rewrite.
697692
*/
698-
RelationOpenSmgr(state->rs_new_rel);
699-
700693
PageSetChecksumInplace(page, state->rs_blockno);
701694

702-
smgrextend(state->rs_new_rel->rd_smgr, MAIN_FORKNUM,
695+
smgrextend(RelationGetSmgr(state->rs_new_rel), MAIN_FORKNUM,
703696
state->rs_blockno, (char *) page, true);
704697

705698
state->rs_blockno++;

‎src/backend/access/heap/visibilitymap.c‎

Lines changed: 27 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -455,13 +455,11 @@ visibilitymap_prepare_truncate(Relation rel, BlockNumber nheapblocks)
455455
elog(DEBUG1, "vm_truncate %s %d", RelationGetRelationName(rel), nheapblocks);
456456
#endif
457457

458-
RelationOpenSmgr(rel);
459-
460458
/*
461459
* If no visibility map has been created yet for this relation, there's
462460
* nothing to truncate.
463461
*/
464-
if (!smgrexists(rel->rd_smgr, VISIBILITYMAP_FORKNUM))
462+
if (!smgrexists(RelationGetSmgr(rel), VISIBILITYMAP_FORKNUM))
465463
return InvalidBlockNumber;
466464

467465
/*
@@ -528,7 +526,7 @@ visibilitymap_prepare_truncate(Relation rel, BlockNumber nheapblocks)
528526
else
529527
newnblocks = truncBlock;
530528

531-
if (smgrnblocks(rel->rd_smgr, VISIBILITYMAP_FORKNUM) <= newnblocks)
529+
if (smgrnblocks(RelationGetSmgr(rel), VISIBILITYMAP_FORKNUM) <= newnblocks)
532530
{
533531
/* nothing to do, the file was already smaller than requested size */
534532
return InvalidBlockNumber;
@@ -547,30 +545,29 @@ static Buffer
547545
vm_readbuf(Relation rel, BlockNumber blkno, bool extend)
548546
{
549547
Buffer buf;
548+
SMgrRelation reln;
550549

551550
/*
552-
* We might not have opened the relation at the smgr level yet, or we
553-
* might have been forced to close it by a sinval message. The code below
554-
* won't necessarily notice relation extension immediately when extend =
555-
* false, so we rely on sinval messages to ensure that our ideas about the
556-
* size of the map aren't too far out of date.
551+
* Caution: re-using this smgr pointer could fail if the relcache entry
552+
* gets closed. It's safe as long as we only do smgr-level operations
553+
* between here and the last use of the pointer.
557554
*/
558-
RelationOpenSmgr(rel);
555+
reln = RelationGetSmgr(rel);
559556

560557
/*
561558
* If we haven't cached the size of the visibility map fork yet, check it
562559
* first.
563560
*/
564-
if (rel->rd_smgr->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] == InvalidBlockNumber)
561+
if (reln->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] == InvalidBlockNumber)
565562
{
566-
if (smgrexists(rel->rd_smgr, VISIBILITYMAP_FORKNUM))
567-
smgrnblocks(rel->rd_smgr, VISIBILITYMAP_FORKNUM);
563+
if (smgrexists(reln, VISIBILITYMAP_FORKNUM))
564+
smgrnblocks(reln, VISIBILITYMAP_FORKNUM);
568565
else
569-
rel->rd_smgr->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] = 0;
566+
reln->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] = 0;
570567
}
571568

572569
/* Handle requests beyond EOF */
573-
if (blkno >= rel->rd_smgr->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM])
570+
if (blkno >= reln->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM])
574571
{
575572
if (extend)
576573
vm_extend(rel, blkno + 1);
@@ -618,6 +615,7 @@ vm_extend(Relation rel, BlockNumber vm_nblocks)
618615
{
619616
BlockNumber vm_nblocks_now;
620617
PGAlignedBlock pg;
618+
SMgrRelation reln;
621619

622620
PageInit((Page) pg.data, BLCKSZ, 0);
623621

@@ -633,29 +631,32 @@ vm_extend(Relation rel, BlockNumber vm_nblocks)
633631
*/
634632
LockRelationForExtension(rel, ExclusiveLock);
635633

636-
/* Might have to re-open if a cache flush happened */
637-
RelationOpenSmgr(rel);
634+
/*
635+
* Caution: re-using this smgr pointer could fail if the relcache entry
636+
* gets closed. It's safe as long as we only do smgr-level operations
637+
* between here and the last use of the pointer.
638+
*/
639+
reln = RelationGetSmgr(rel);
638640

639641
/*
640642
* Create the file first if it doesn't exist. If smgr_vm_nblocks is
641643
* positive then it must exist, no need for an smgrexists call.
642644
*/
643-
if ((rel->rd_smgr->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] == 0 ||
644-
rel->rd_smgr->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] == InvalidBlockNumber) &&
645-
!smgrexists(rel->rd_smgr, VISIBILITYMAP_FORKNUM))
646-
smgrcreate(rel->rd_smgr, VISIBILITYMAP_FORKNUM, false);
645+
if ((reln->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] == 0 ||
646+
reln->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] == InvalidBlockNumber) &&
647+
!smgrexists(reln, VISIBILITYMAP_FORKNUM))
648+
smgrcreate(reln, VISIBILITYMAP_FORKNUM, false);
647649

648650
/* Invalidate cache so that smgrnblocks() asks the kernel. */
649-
rel->rd_smgr->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] = InvalidBlockNumber;
650-
vm_nblocks_now = smgrnblocks(rel->rd_smgr, VISIBILITYMAP_FORKNUM);
651+
reln->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] = InvalidBlockNumber;
652+
vm_nblocks_now = smgrnblocks(reln, VISIBILITYMAP_FORKNUM);
651653

652654
/* Now extend the file */
653655
while (vm_nblocks_now < vm_nblocks)
654656
{
655657
PageSetChecksumInplace((Page) pg.data, vm_nblocks_now);
656658

657-
smgrextend(rel->rd_smgr, VISIBILITYMAP_FORKNUM, vm_nblocks_now,
658-
pg.data, false);
659+
smgrextend(reln, VISIBILITYMAP_FORKNUM, vm_nblocks_now, pg.data, false);
659660
vm_nblocks_now++;
660661
}
661662

@@ -666,7 +667,7 @@ vm_extend(Relation rel, BlockNumber vm_nblocks)
666667
* to keep checking for creation or extension of the file, which happens
667668
* infrequently.
668669
*/
669-
CacheInvalidateSmgr(rel->rd_smgr->smgr_rnode);
670+
CacheInvalidateSmgr(reln->smgr_rnode);
670671

671672
UnlockRelationForExtension(rel, ExclusiveLock);
672673
}

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