[LU-15108] Wrong changelog issued during hsm_restore

• Type: Bug
• Resolution: Unresolved
• Priority: Minor
• Environment: VMs on Lustre master (2.14.54_98_g3db8e31)
• Severity: 3
• Assignee: Etienne Aujames
• Reporter: Etienne Aujames

Description

Here are the changelogs that we can see while restoring a hsm file:

30 10OPEN  10:43:26.912661570 2021.10.15 0xcb t=[0x200000402:0xa:0x0] j=lhsmtool_posix.0 ef=0xf u=0:0 nid=10.0.2.6@tcp m=rw-
31 10OPEN  10:43:26.920553291 2021.10.15 0x2 t=[0x200000402:0xa:0x0] j=lhsmtool_posix.0 ef=0xf u=0:0 nid=10.0.2.6@tcp m=-w-
32 16HSM   10:43:26.966607124 2021.10.15 0x0 t=[0x200000402:0x1:0x0] j=lhsmtool_posix.0 ef=0xf u=0:0 nid=10.0.2.6@tcp
33 12LYOUT 10:43:26.967682430 2021.10.15 0x0 t=[0x200000402:0x1:0x0] j=lhsmtool_posix.0 ef=0xf u=0:0 nid=10.0.2.6@tcp
34 16HSM   10:43:26.969154222 2021.10.15 0x80 t=[0x200000402:0x1:0x0] j=lhsmtool_posix.0 ef=0xf u=0:0 nid=10.0.2.6@tcp

The changelog 32 is wrong: flag: 0x0 -> err=0 hsm_event: HE_ARCHIVE hsm_flag=0
The changelog 34 is the right one: 0x80 -> err=0 hsm_event: HE_RESTORE hsm_flag=0

I think changelog 32 should be set flag to 0x280: err=0 hsm_event: HE_STATE hsm_flag=0

The wrong flag is positioned because of the following code (when updating hsm state attr):

static int mdd_hsm_update_locked(const struct lu_env *env,
                                 struct md_object *obj,
                                 const struct lu_buf *buf,
                                 struct thandle *handle,
                                 enum changelog_rec_flags *clf_flags)
{
.....
       /* Flags differ, set flags for the changelog that will be added */
        if (current_mh->mh_flags != new_mh->mh_flags) {                  <----------
                hsm_set_cl_event(clf_flags, HE_STATE);
                if (new_mh->mh_flags & HS_DIRTY)
                        hsm_set_cl_flags(clf_flags, CLF_HSM_DIRTY);
        }

When restoring a file, hsm xattr is updated by hsm_swap_layouts on the volatile (so no changelog are emitted there):

static int hsm_swap_layouts(struct mdt_thread_info *mti,
                            struct mdt_object *obj, const struct lu_fid *dfid,
                            struct md_hsm *mh_common)
{
.....
        mh_common->mh_flags &= ~(HS_RELEASED | HS_DIRTY);
        rc = mdt_hsm_attr_set(mti, dobj, mh_common);

So empty HSM changelog is issued by hsm_cdt_request_completed() -> mdt_hsm_attr_set() because hsm state is not modified by this function.