Date: Tue, 8 Aug 2017 11:13:27 +0000 (UTC) From: Andriy Gapon <avg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-vendor@freebsd.org Subject: svn commit: r322236 - vendor-sys/illumos/dist/uts/common/fs/zfs Message-ID: <201708081113.v78BDRba043186@repo.freebsd.org>
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Author: avg Date: Tue Aug 8 11:13:27 2017 New Revision: 322236 URL: https://svnweb.freebsd.org/changeset/base/322236 Log: 8126 ztest assertion failed in dbuf_dirty due to dn_nlevels changing illumos/illumos-gate@dcb6872c565819ac88acbc2ece999ef241c8b982 https://github.com/illumos/illumos-gate/commit/dcb6872c565819ac88acbc2ece999ef241c8b982 https://www.illumos.org/issues/8126 The sync thread is concurrently modifying dn_phys->dn_nlevels while dbuf_dirty() is trying to assert something about it, without holding the necessary lock. We need to move this assertion further down in the function, after we have acquired the dn_struct_rwlock. Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com> Reviewed by: Serapheim Dimitropoulos <serapheim@delphix.com> Approved by: Robert Mustacchi <rm@joyent.com> Author: Matthew Ahrens <mahrens@delphix.com> Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/dbuf.c Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/dbuf.c ============================================================================== --- vendor-sys/illumos/dist/uts/common/fs/zfs/dbuf.c Tue Aug 8 11:10:37 2017 (r322235) +++ vendor-sys/illumos/dist/uts/common/fs/zfs/dbuf.c Tue Aug 8 11:13:27 2017 (r322236) @@ -1542,11 +1542,6 @@ dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx) (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN)); ASSERT3U(dn->dn_nlevels, >, db->db_level); - ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) || - dn->dn_phys->dn_nlevels > db->db_level || - dn->dn_next_nlevels[txgoff] > db->db_level || - dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level || - dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level); /* * We should only be dirtying in syncing context if it's the @@ -1662,6 +1657,16 @@ dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx) rw_enter(&dn->dn_struct_rwlock, RW_READER); drop_struct_lock = TRUE; } + + /* + * We need to hold the dn_struct_rwlock to make this assertion, + * because it protects dn_phys / dn_next_nlevels from changing. + */ + ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) || + dn->dn_phys->dn_nlevels > db->db_level || + dn->dn_next_nlevels[txgoff] > db->db_level || + dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level || + dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level); /* * If we are overwriting a dedup BP, then unless it is snapshotted,
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