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Don't call PageGetSpecialPointer() on page until it's been initialized.

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After calling XLogInitBufferForRedo(), the page might be all-zeros if it was
not in page cache already. btree_xlog_unlink_page initialized the page
correctly, but it called PageGetSpecialPointer before initializing it, which
would lead to a corrupt page at WAL replay, if the unlinked page is not in
page cache.

Backpatch to 9.4, the bug came with the rewrite of B-tree page deletion.
This commit is contained in:
Heikki Linnakangas 2015-06-30 13:37:16 +03:00
parent 1afc1fe9c7
commit 7dc721889b
1 changed files with 2 additions and 1 deletions
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3
src/backend/access/nbtree/nbtxlog.c
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@ -997,9 +997,10 @@ btree_xlog_unlink_page(uint8 info, XLogRecPtr lsn, XLogRecord *record)
buffer = XLogReadBuffer(xlrec->node, xlrec->leafblk, true); buffer = XLogReadBuffer(xlrec->node, xlrec->leafblk, true);
Assert(BufferIsValid(buffer)); Assert(BufferIsValid(buffer));
page = (Page) BufferGetPage(buffer); page = (Page) BufferGetPage(buffer);
pageop = (BTPageOpaque) PageGetSpecialPointer(page);
_bt_pageinit(page, BufferGetPageSize(buffer)); _bt_pageinit(page, BufferGetPageSize(buffer));
pageop = (BTPageOpaque) PageGetSpecialPointer(page);
pageop->btpo_flags = BTP_HALF_DEAD | BTP_LEAF; pageop->btpo_flags = BTP_HALF_DEAD | BTP_LEAF;
pageop->btpo_prev = xlrec->leafleftsib; pageop->btpo_prev = xlrec->leafleftsib;
pageop->btpo_next = xlrec->leafrightsib; pageop->btpo_next = xlrec->leafrightsib;