Date: Thu, 22 Feb 2018 11:41:00 +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: r329820 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs Message-ID: <201802221141.w1MBf0dI046892@repo.freebsd.org>
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Author: avg Date: Thu Feb 22 11:41:00 2018 New Revision: 329820 URL: https://svnweb.freebsd.org/changeset/base/329820 Log: followup to r329556, completely remove the covered vnode assert vrele() acquires the vnode lock only if the hold count drops to zero. In other scenarios it needs only the interlock. So, zfsctl_snapdir_lookup() can race with vfs_mount_destroy() -> vrele() such that the lookup adds a new reference and then vrele() drops the mountpoint's reference and only then we check the reference count. It would be just one in this case. In fact, the assert should have been removed in r323483 when the code learned how to deal with the uncovered vnode. PR: 225795 MFC after: 4 days X-MFC with: r329556 Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c ============================================================================== --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c Thu Feb 22 11:18:33 2018 (r329819) +++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c Thu Feb 22 11:41:00 2018 (r329820) @@ -976,13 +976,6 @@ zfsctl_snapdir_lookup(ap) break; /* - * The vnode must be referenced at least by this thread and - * the mount point or the thread doing the mounting. - * There can be more references from concurrent lookups. - */ - KASSERT((*vpp)->v_holdcnt > 1, ("found unheld mountpoint")); - - /* * Check if a snapshot is already mounted on top of the vnode. */ err = zfsctl_mounted_here(vpp, lkflags);
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