From 5e0bd0ae056e26de36dee3c199c6fcff8f14ee15 Mon Sep 17 00:00:00 2001 From: Tom Caputi Date: Thu, 18 Oct 2018 04:13:07 -0400 Subject: [PATCH] Fix issue with scanning dedup blocks as scan ends This patch fixes an issue discovered by ztest where dsl_scan_ddt_entry() could add I/Os to the dsl scan queues between when the scan had finished all required work and when the scan was marked as complete. This caused the scan to spin indefinitely without ending. Reviewed-by: Brian Behlendorf Reviewed-by: Serapheim Dimitropoulos Reviewed-by: Matthew Ahrens Signed-off-by: Tom Caputi Closes #8010 --- module/zfs/dsl_scan.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/module/zfs/dsl_scan.c b/module/zfs/dsl_scan.c index aff99f275..db3295363 100644 --- a/module/zfs/dsl_scan.c +++ b/module/zfs/dsl_scan.c @@ -2386,6 +2386,20 @@ dsl_scan_ddt_entry(dsl_scan_t *scn, enum zio_checksum checksum, if (!dsl_scan_is_running(scn)) return; + /* + * This function is special because it is the only thing + * that can add scan_io_t's to the vdev scan queues from + * outside dsl_scan_sync(). For the most part this is ok + * as long as it is called from within syncing context. + * However, dsl_scan_sync() expects that no new sio's will + * be added between when all the work for a scan is done + * and the next txg when the scan is actually marked as + * completed. This check ensures we do not issue new sio's + * during this period. + */ + if (scn->scn_done_txg != 0) + return; + for (p = 0; p < DDT_PHYS_TYPES; p++, ddp++) { if (ddp->ddp_phys_birth == 0 || ddp->ddp_phys_birth > scn->scn_phys.scn_max_txg) @@ -3468,6 +3482,8 @@ dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t *tx) (longlong_t)tx->tx_txg); } } else if (scn->scn_is_sorted && scn->scn_bytes_pending != 0) { + ASSERT(scn->scn_clearing); + /* need to issue scrubbing IOs from per-vdev queues */ scn->scn_zio_root = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_CANFAIL);