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help / color / mirror / Atom feedFrom: Melanie Plageman <[email protected]>
Subject: [PATCH v8 4/9] Fix off-by-one error in read IO tracing
Date: Mon, 16 Mar 2026 16:50:56 -0400
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 <[email protected]>
Reviewed-by: Andres Freund <[email protected]>
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
--zousfcpkuk57oxzf
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v8-0005-Pass-io_object-and-io_context-through-to-PinBuffe.patch"
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