Date: Wed, 13 Jul 2016 10:11:57 +0000 (UTC) From: Andriy Gapon <avg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org Subject: svn commit: r302749 - stable/9/sys/cddl/contrib/opensolaris/uts/common/fs/zfs Message-ID: <201607131011.u6DABvAM007214@repo.freebsd.org>
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Author: avg Date: Wed Jul 13 10:11:57 2016 New Revision: 302749 URL: https://svnweb.freebsd.org/changeset/base/302749 Log: MFC r299945: avoid deadlock between zfsctl_snapdir_lookup and zfsctl_snapshot_reclaim Modified: stable/9/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c Directory Properties: stable/9/sys/ (props changed) stable/9/sys/cddl/contrib/opensolaris/ (props changed) Modified: stable/9/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c ============================================================================== --- stable/9/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c Wed Jul 13 10:11:48 2016 (r302748) +++ stable/9/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_ctldir.c Wed Jul 13 10:11:57 2016 (r302749) @@ -997,6 +997,7 @@ zfsctl_snapdir_lookup(ap) #endif } +relookup: mutex_enter(&sdp->sd_lock); search.se_name = (char *)nm; if ((sep = avl_find(&sdp->sd_snaps, &search, &where)) != NULL) { @@ -1064,7 +1065,16 @@ domount: (void) snprintf(mountpoint, mountpoint_len, "%s/" ZFS_CTLDIR_NAME "/snapshot/%s", dvp->v_vfsp->mnt_stat.f_mntonname, nm); - VERIFY0(vn_lock(*vpp, LK_EXCLUSIVE)); + mutex_exit(&sdp->sd_lock); + + /* + * The vnode may get reclaimed between dropping sd_lock and + * getting the vnode lock. + * */ + err = vn_lock(*vpp, LK_EXCLUSIVE); + if (err == ENOENT) + goto relookup; + VERIFY0(err); err = mount_snapshot(curthread, vpp, "zfs", mountpoint, snapname, 0); kmem_free(mountpoint, mountpoint_len); if (err == 0) { @@ -1078,7 +1088,6 @@ domount: ASSERT(VTOZ(*vpp)->z_zfsvfs != zfsvfs); VTOZ(*vpp)->z_zfsvfs->z_parent = zfsvfs; } - mutex_exit(&sdp->sd_lock); ZFS_EXIT(zfsvfs); #ifdef illumos
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