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Replace RelationOpenSmgr() with RelationGetSmgr().

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The idea behind this patch is to design out bugs like the one fixed
by commit 9d523119f.  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
This commit is contained in:
Tom Lane
2021-07-12 17:01:29 -04:00
parent 5b60cf35f5
commit f10f0ae420
21 changed files with 164 additions and 165 deletions
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14
src/backend/access/spgist/spginsert.c
View File

@ -169,27 +169,27 @@ spgbuildempty(Relation index)
* replayed.
*/
PageSetChecksumInplace(page, SPGIST_METAPAGE_BLKNO);
smgrwrite(index->rd_smgr, INIT_FORKNUM, SPGIST_METAPAGE_BLKNO,
smgrwrite(RelationGetSmgr(index), INIT_FORKNUM, SPGIST_METAPAGE_BLKNO,
(char *) page, true);
log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM,
log_newpage(&(RelationGetSmgr(index))->smgr_rnode.node, INIT_FORKNUM,
SPGIST_METAPAGE_BLKNO, page, true);
/* Likewise for the root page. */
SpGistInitPage(page, SPGIST_LEAF);
PageSetChecksumInplace(page, SPGIST_ROOT_BLKNO);
smgrwrite(index->rd_smgr, INIT_FORKNUM, SPGIST_ROOT_BLKNO,
smgrwrite(RelationGetSmgr(index), INIT_FORKNUM, SPGIST_ROOT_BLKNO,
(char *) page, true);
log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM,
log_newpage(&(RelationGetSmgr(index))->smgr_rnode.node, INIT_FORKNUM,
SPGIST_ROOT_BLKNO, page, true);
/* Likewise for the null-tuples root page. */
SpGistInitPage(page, SPGIST_LEAF | SPGIST_NULLS);
PageSetChecksumInplace(page, SPGIST_NULL_BLKNO);
smgrwrite(index->rd_smgr, INIT_FORKNUM, SPGIST_NULL_BLKNO,
smgrwrite(RelationGetSmgr(index), INIT_FORKNUM, SPGIST_NULL_BLKNO,
(char *) page, true);
log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM,
log_newpage(&(RelationGetSmgr(index))->smgr_rnode.node, INIT_FORKNUM,
SPGIST_NULL_BLKNO, page, true);
/*
@ -197,7 +197,7 @@ spgbuildempty(Relation index)
* writes did not go through shared buffers and therefore a concurrent
* checkpoint may have moved the redo pointer past our xlog record.
*/
smgrimmedsync(index->rd_smgr, INIT_FORKNUM);
smgrimmedsync(RelationGetSmgr(index), INIT_FORKNUM);
}
/*