From 20c22333630111718bc97ce9a19b392f23e3c525 Mon Sep 17 00:00:00 2001 From: Amit Kapila Date: Mon, 14 Nov 2022 10:11:10 +0530 Subject: [PATCH] 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 --- src/backend/access/hash/hash_xlog.c | 5 ++--- src/backend/access/hash/hashpage.c | 10 +++++++--- 2 files changed, 9 insertions(+), 6 deletions(-) diff --git a/src/backend/access/hash/hash_xlog.c b/src/backend/access/hash/hash_xlog.c index 3c60677662..0a178b78cf 100644 --- a/src/backend/access/hash/hash_xlog.c +++ b/src/backend/access/hash/hash_xlog.c @@ -352,11 +352,10 @@ 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); diff --git a/src/backend/access/hash/hashpage.c b/src/backend/access/hash/hashpage.c index a664ecf494..1e6cf49fb1 100644 --- a/src/backend/access/hash/hashpage.c +++ b/src/backend/access/hash/hashpage.c @@ -804,9 +804,13 @@ 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))