From 91579709fccd3e55a21970742b66c388fb1403db Mon Sep 17 00:00:00 2001 From: Brian Behlendorf Date: Mon, 17 Dec 2012 16:23:27 -0800 Subject: [PATCH] Fix __zio_execute() asynchronous dispatch To save valuable stack all zio's were made asynchronous when in the tgx_sync_thread context or during pool initialization. See commit 2fac4c2 for the original patch and motivation. Unfortuantely, the changes to dsl_pool_sync_context() made by the feature flags broke this logic causing in __zio_execute() to dispatch itself infinitely when called during pool initialization. This commit refines the existing logic to specificly target only the two cases we care about. Signed-off-by: Brian Behlendorf --- module/zfs/zio.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) diff --git a/module/zfs/zio.c b/module/zfs/zio.c index 66f228bc7..638105a09 100644 --- a/module/zfs/zio.c +++ b/module/zfs/zio.c @@ -1248,7 +1248,7 @@ __zio_execute(zio_t *zio) while (zio->io_stage < ZIO_STAGE_DONE) { enum zio_stage pipeline = zio->io_pipeline; enum zio_stage stage = zio->io_stage; - dsl_pool_t *dsl; + dsl_pool_t *dp; boolean_t cut; int rv; @@ -1262,7 +1262,7 @@ __zio_execute(zio_t *zio) ASSERT(stage <= ZIO_STAGE_DONE); - dsl = spa_get_dsl(zio->io_spa); + dp = spa_get_dsl(zio->io_spa); cut = (stage == ZIO_STAGE_VDEV_IO_START) ? zio_requeue_io_start_cut_in_line : B_FALSE; @@ -1272,16 +1272,24 @@ __zio_execute(zio_t *zio) * or may wait for an I/O that needs an interrupt thread * to complete, issue async to avoid deadlock. * - * If we are in the txg_sync_thread or being called - * during pool init issue async to minimize stack depth. - * Both of these call paths may be recursively called. - * * For VDEV_IO_START, we cut in line so that the io will * be sent to disk promptly. */ - if (((stage & ZIO_BLOCKING_STAGES) && zio->io_vd == NULL && - zio_taskq_member(zio, ZIO_TASKQ_INTERRUPT)) || - (dsl != NULL && dsl_pool_sync_context(dsl))) { + if ((stage & ZIO_BLOCKING_STAGES) && zio->io_vd == NULL && + zio_taskq_member(zio, ZIO_TASKQ_INTERRUPT)) { + zio_taskq_dispatch(zio, ZIO_TASKQ_ISSUE, cut); + return; + } + + /* + * If we executing in the context of the tx_sync_thread, + * or we are performing pool initialization outside of a + * zio_taskq[ZIO_TASKQ_ISSUE] context. Then issue the zio + * async to minimize stack usage for these deep call paths. + */ + if ((dp && curthread == dp->dp_tx.tx_sync_thread) || + (dp && spa_is_initializing(dp->dp_spa) && + !zio_taskq_member(zio, ZIO_TASKQ_ISSUE))) { zio_taskq_dispatch(zio, ZIO_TASKQ_ISSUE, cut); return; }