Date: Mon, 12 Aug 2019 10:30:01 +0000 (UTC) From: Andriy Gapon <avg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r350894 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs Message-ID: <201908121030.x7CAU11q053608@repo.freebsd.org>
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Author: avg Date: Mon Aug 12 10:30:00 2019 New Revision: 350894 URL: https://svnweb.freebsd.org/changeset/base/350894 Log: a stop gap fix for a race between dnode_hold and dnode_sync_free The race was introduced in r337669, the large dnode feature import from ZoL. The problem was debugged by ZoL developers and then, independently, on FreeBSD. The fix is an early proposal by Brian Behlendorf: https://github.com/behlendorf/zfs/commit/50f32ed74e42aa28522e9681fb8ae55239fa33a7 This fix never went into ZoL. A larger change that was committed later included a different solution because of the re-worked code. Ideally, we want to revert this fix and re-synchronize FreeBSD large dnode code with that in illumos (or newer ZoL). illumos has a later import of the feature from ZoL that does not have the bug. PR: 236480 Obtained from: Brian Behlendorf <behlendorf1@llnl.gov> Submitted by: ncrogers@gmail.com (patch adaptation) Reported by: ncrogers@gmail.com Tested by: ncrogers@gmail.com, Dennis Noordsij <dennis.noordsij@alumni.helsinki.fi>, Julien Cigar <julien@perdition.city> MFC after: 10 days Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c ============================================================================== --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c Mon Aug 12 10:00:32 2019 (r350893) +++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c Mon Aug 12 10:30:00 2019 (r350894) @@ -1324,7 +1324,9 @@ dnode_hold_impl(objset_t *os, uint64_t object, int fla mutex_enter(&dn->dn_mtx); type = dn->dn_type; if (dn->dn_free_txg || - ((flag & DNODE_MUST_BE_FREE) && !refcount_is_zero(&dn->dn_holds))) { + ((flag & DNODE_MUST_BE_ALLOCATED) && type == DMU_OT_NONE) || + ((flag & DNODE_MUST_BE_FREE) && + (type != DMU_OT_NONE || !refcount_is_zero(&dn->dn_holds)))) { mutex_exit(&dn->dn_mtx); zrl_remove(&dnh->dnh_zrlock); dbuf_rele(db, FTAG);
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