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Fix cleanup lock acquisition in SPLIT_ALLOCATE_PAGE replay. 

During XLOG_HASH_SPLIT_ALLOCATE_PAGE replay, we were checking for a
cleanup lock on the new bucket page after acquiring an exclusive lock on
it and raising a PANIC error on failure. However, it is quite possible
that checkpointer can acquire the pin on the same page before acquiring a
lock on it, and then the replay will lead to an error. So instead, directly
acquire the cleanup lock on the new bucket page during
XLOG_HASH_SPLIT_ALLOCATE_PAGE replay operation.

Reported-by: Andres Freund
Author: Robert Haas
Reviewed-By: Amit Kapila, Andres Freund, Vignesh C
Backpatch-through: 11
Discussion: https://postgr.es/m/20220810022617.fvjkjiauaykwrbse@awork3.anarazel.de
This commit is contained in:
Amit Kapila 2022-11-14 10:43:33 +05:30
parent ad6c52846f
commit e848be60b5
2 changed files with 9 additions and 6 deletions
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5
src/backend/access/hash/hash_xlog.c
View File

@ -351,11 +351,10 @@ hash_xlog_split_allocate_page(XLogReaderState *record)
}
/* replay the record for new bucket */
newbuf = XLogInitBufferForRedo(record, 1);
XLogReadBufferForRedoExtended(record, 1, RBM_ZERO_AND_CLEANUP_LOCK, true,
&newbuf);
_hash_initbuf(newbuf, xlrec->new_bucket, xlrec->new_bucket,
xlrec->new_bucket_flag, true);
if (!IsBufferCleanupOK(newbuf))
elog(PANIC, "hash_xlog_split_allocate_page: failed to acquire cleanup lock");
MarkBufferDirty(newbuf);
PageSetLSN(BufferGetPage(newbuf), lsn);

10
src/backend/access/hash/hashpage.c
View File

@ -805,9 +805,13 @@ restart_expand:
/*
* Physically allocate the new bucket's primary page. We want to do this
* before changing the metapage's mapping info, in case we can't get the
* disk space. Ideally, we don't need to check for cleanup lock on new
* bucket as no other backend could find this bucket unless meta page is
* updated. However, it is good to be consistent with old bucket locking.
* disk space.
*
* XXX It doesn't make sense to call _hash_getnewbuf first, zeroing the
* buffer, and then only afterwards check whether we have a cleanup lock.
* However, since no scan can be accessing the buffer yet, any concurrent
* accesses will just be from processes like the bgwriter or checkpointer
* which don't care about its contents, so it doesn't really matter.
*/
buf_nblkno = _hash_getnewbuf(rel, start_nblkno, MAIN_FORKNUM);
if (!IsBufferCleanupOK(buf_nblkno))