Fix shared memory calculation size of PgAioCtl

michaelpq · michaelpq · commit dd74e599b8f6 · 2025-09-17T09:33:35.000+09:00
The shared memory size was calculated based on an offset of io_handles, which is itself a pointer included in the structure. We tend to overestimate the shared memory size overall, so this was unlikely an issue in practice, but let's be correct and use the full size of the structure in the calculation, so as the pointer for io_handles is included. Oversight in da72269. Author: Madhukar Prasad <madhukarprasad@google.com> Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Matthias van de Meent <boekewurm+postgres@gmail.com> Discussion: https://postgr.es/m/CAKi+wrbC2dTzh_vKJoAZXV5wqTbhY0n4wRNpCjJ=e36aoo0kFw@mail.gmail.com Backpatch-through: 18
diff --git a/src/backend/storage/aio/aio_init.c b/src/backend/storage/aio/aio_init.c
@@ -30,12 +30,8 @@
 static Size
 AioCtlShmemSize(void)
 {
-	Size		sz;
-
 	/* pgaio_ctl itself */
-	sz = offsetof(PgAioCtl, io_handles);
-
-	return sz;
+	return sizeof(PgAioCtl);
 }
 
 static uint32

Original file line number	Diff line number	Diff line change
`@@ -30,12 +30,8 @@`
`30`	`30`	`static Size`
`31`	`31`	`AioCtlShmemSize(void)`
`32`	`32`	`{`
`33`		`- Size sz;`
`34`		`-`
`35`	`33`	`/* pgaio_ctl itself */`
`36`		`- sz = offsetof(PgAioCtl, io_handles);`
`37`		`-`
`38`		`- return sz;`
	`34`	`+ return sizeof(PgAioCtl);`
`39`	`35`	`}`
`40`	`36`
`41`	`37`	`static uint32`