diff options
Diffstat (limited to 'src/backend/storage/aio/aio.c')
| -rw-r--r-- | src/backend/storage/aio/aio.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/src/backend/storage/aio/aio.c b/src/backend/storage/aio/aio.c index 64e8e81e184..e2a133cfac6 100644 --- a/src/backend/storage/aio/aio.c +++ b/src/backend/storage/aio/aio.c @@ -670,6 +670,21 @@ pgaio_io_reclaim(PgAioHandle *ioh) Assert(!ioh->resowner); + /* + * Update generation & state first, before resetting the IO's fields, + * otherwise a concurrent "viewer" could think the fields are valid, even + * though they are being reset. Increment the generation first, so that + * we can assert elsewhere that we never wait for an IDLE IO. While it's + * a bit weird for the state to go backwards for a generation, it's OK + * here, as there cannot be references to the "reborn" IO yet. Can't + * update both at once, so something has to give. + */ + ioh->generation++; + pgaio_io_update_state(ioh, PGAIO_HS_IDLE); + + /* ensure the state update is visible before we reset fields */ + pg_write_barrier(); + ioh->op = PGAIO_OP_INVALID; ioh->target = PGAIO_TID_INVALID; ioh->flags = 0; @@ -679,12 +694,6 @@ pgaio_io_reclaim(PgAioHandle *ioh) ioh->result = 0; ioh->distilled_result.status = PGAIO_RS_UNKNOWN; - /* XXX: the barrier is probably superfluous */ - pg_write_barrier(); - ioh->generation++; - - pgaio_io_update_state(ioh, PGAIO_HS_IDLE); - /* * We push the IO to the head of the idle IO list, that seems more cache * efficient in cases where only a few IOs are used. |