From 2725c524a3f057e6cd4f16fe9e2393bf6546932b Mon Sep 17 00:00:00 2001 From: Melanie Plageman Date: Mon, 16 Mar 2026 16:50:56 -0400 Subject: [PATCH v7a 3/8] Fix off-by-one error in read IO tracing AsyncReadBuffer()'s no-IO needed path passed TRACE_POSTGRESQL_BUFFER_READ_DONE the wrong block number because it had already incremented operation->nblocks_done. Fix by folding the nblocks_done offset into the blocknum local variable at initialization. Author: Melanie Plageman Reviewed-by: Andres Freund Discussion: https://postgr.es/m/u73un3xeljr4fiidzwi4ikcr6vm7oqugn4fo5vqpstjio6anl2%40hph6fvdiiria --- src/backend/storage/buffer/bufmgr.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index 00bc609529a..10afae1990b 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -1875,10 +1875,10 @@ AsyncReadBuffers(ReadBuffersOperation *operation, int *nblocks_progress) { Buffer *buffers = &operation->buffers[0]; int flags = operation->flags; - BlockNumber blocknum = operation->blocknum; ForkNumber forknum = operation->forknum; char persistence = operation->persistence; int16 nblocks_done = operation->nblocks_done; + BlockNumber blocknum = operation->blocknum + nblocks_done; Buffer *io_buffers = &operation->buffers[nblocks_done]; int io_buffers_len = 0; PgAioHandle *ioh; @@ -1990,7 +1990,7 @@ AsyncReadBuffers(ReadBuffersOperation *operation, int *nblocks_progress) * must have started out as a miss in PinBufferForBlock(). The other * backend will track this as a 'read'. */ - TRACE_POSTGRESQL_BUFFER_READ_DONE(forknum, blocknum + operation->nblocks_done, + TRACE_POSTGRESQL_BUFFER_READ_DONE(forknum, blocknum, operation->smgr->smgr_rlocator.locator.spcOid, operation->smgr->smgr_rlocator.locator.dbOid, operation->smgr->smgr_rlocator.locator.relNumber, @@ -2062,7 +2062,7 @@ AsyncReadBuffers(ReadBuffersOperation *operation, int *nblocks_progress) */ io_start = pgstat_prepare_io_time(track_io_timing); smgrstartreadv(ioh, operation->smgr, forknum, - blocknum + nblocks_done, + blocknum, io_pages, io_buffers_len); pgstat_count_io_op_time(io_object, io_context, IOOP_READ, io_start, 1, io_buffers_len * BLCKSZ); -- 2.53.0.1.gb2826b52eb