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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