LU-10769 osd-zfs: fix deadlock on osd_object::oo_guard

There is race condition inside osd-zfs, it may cause deadlock.
Consider the following scenarios:

1) The Thread1 calls osd_attr_set() to set flags on the object.
   The osd_attr_set() will call the osd_xattr_get() with holding
   the read mode semaphore on the object::oo_guard.

2) The Thread2 calls the osd_declare_destroy() to destroy such
   object, it will down_write() on the object::oo_gurad, but be
   blocked by the Thread1's granted read mode semaphore.

3) The osd_xattr_get() triggered by the osd_xattr_set() will also
   down_read() on the object::oo_guard. But it will be blocked by
   the Thread2's pending down_write() request.

Then the Thread1 and the Thread2 deadlock.
This patch makes the osd_attr_set() to call the lockless version
xattr_get osd_xattr_get_internal() to avoid such deadlock.

Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: Iaac2e414b5f1fd197303bb7ec7d5e2763b6f3e9a
Reviewed-on: https://review.whamcloud.com/31511
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>

diff --git a/lustre/osd-zfs/osd_internal.h b/lustre/osd-zfs/osd_internal.h
index 5c72d58..4877600 100644 (file)
--- a/lustre/osd-zfs/osd_internal.h
+++ b/lustre/osd-zfs/osd_internal.h
@@ -609,7 +609,6 @@ int __osd_attr_init(const struct lu_env *env, struct osd_device *osd,
                    struct lu_attr *la, uint64_t parent, nvlist_t *);
 int osd_find_new_dnode(const struct lu_env *env, dmu_tx_t *tx,
                       uint64_t oid, dnode_t **dnp);
                    struct lu_attr *la, uint64_t parent, nvlist_t *);
 int osd_find_new_dnode(const struct lu_env *env, dmu_tx_t *tx,
                       uint64_t oid, dnode_t **dnp);

-int osd_object_init0(const struct lu_env *env, struct osd_object *obj);

 
 /* osd_oi.c */
 int osd_oi_init(const struct lu_env *env, struct osd_device *o);
 
 /* osd_oi.c */
 int osd_oi_init(const struct lu_env *env, struct osd_device *o);

diff --git a/lustre/osd-zfs/osd_object.c b/lustre/osd-zfs/osd_object.c
index c835e92..0734da2 100644 (file)
--- a/lustre/osd-zfs/osd_object.c
+++ b/lustre/osd-zfs/osd_object.c
@@ -186,8 +186,8 @@ osd_object_sa_bulk_update(struct osd_object *obj, sa_bulk_attr_t *attrs,
 /*
  * Retrieve the attributes of a DMU object
  */
 /*
  * Retrieve the attributes of a DMU object
  */

-int __osd_object_attr_get(const struct lu_env *env, struct osd_device *o,
-                         struct osd_object *obj, struct lu_attr *la)
+static int __osd_object_attr_get(const struct lu_env *env, struct osd_device *o,
+                                struct osd_object *obj, struct lu_attr *la)

 {
        struct osa_attr *osa = &osd_oti_get(env)->oti_osa;
        sa_bulk_attr_t  *bulk = osd_oti_get(env)->oti_attr_bulk;
 {
        struct osa_attr *osa = &osd_oti_get(env)->oti_osa;
        sa_bulk_attr_t  *bulk = osd_oti_get(env)->oti_attr_bulk;


@@ -406,7 +406,7 @@ out:
 /*
  * Concurrency: shouldn't matter.
  */
 /*
  * Concurrency: shouldn't matter.
  */

-int osd_object_init0(const struct lu_env *env, struct osd_object *obj)
+static int osd_object_init0(const struct lu_env *env, struct osd_object *obj)

 {
        struct osd_device       *osd = osd_obj2dev(obj);
        const struct lu_fid     *fid = lu_object_fid(&obj->oo_dt.do_lu);
 {
        struct osd_device       *osd = osd_obj2dev(obj);
        const struct lu_fid     *fid = lu_object_fid(&obj->oo_dt.do_lu);


@@ -1264,9 +1264,9 @@ static int osd_attr_set(const struct lu_env *env, struct dt_object *dt,
                        rc = -zap_update(osd->od_os, zapid, buf, 8,
                                         sizeof(*zde) / 8, zde, oh->ot_tx);
                }
                        rc = -zap_update(osd->od_os, zapid, buf, 8,
                                         sizeof(*zde) / 8, zde, oh->ot_tx);
                }

-               up_read(&obj->oo_guard);
-
-               RETURN(rc > 0 ? 0 : rc);
+               if (rc > 0)
+                       rc = 0;
+               GOTO(out, rc);

        }
 
        /* Only allow set size for regular file */
        }
 
        /* Only allow set size for regular file */


@@ -1288,6 +1288,7 @@ static int osd_attr_set(const struct lu_env *env, struct dt_object *dt,
        if (valid & LA_FLAGS) {
                struct lustre_mdt_attrs *lma;
                struct lu_buf buf;
        if (valid & LA_FLAGS) {
                struct lustre_mdt_attrs *lma;
                struct lu_buf buf;

+               int size = 0;

 
                if (la->la_flags & LUSTRE_LMA_FL_MASKS) {
                        LASSERT(!obj->oo_pfid_in_lma);
 
                if (la->la_flags & LUSTRE_LMA_FL_MASKS) {
                        LASSERT(!obj->oo_pfid_in_lma);


@@ -1295,9 +1296,14 @@ static int osd_attr_set(const struct lu_env *env, struct dt_object *dt,
                        lma = (struct lustre_mdt_attrs *)&info->oti_buf;
                        buf.lb_buf = lma;
                        buf.lb_len = sizeof(info->oti_buf);
                        lma = (struct lustre_mdt_attrs *)&info->oti_buf;
                        buf.lb_buf = lma;
                        buf.lb_len = sizeof(info->oti_buf);

-                       rc = osd_xattr_get(env, &obj->oo_dt, &buf,
-                                          XATTR_NAME_LMA);
-                       if (rc > 0) {
+
+                       /* Please do NOT call osd_xattr_get() directly, that
+                        * will cause recursive down_read() on oo_guard. */
+                       rc = osd_xattr_get_internal(env, obj, &buf,
+                                                   XATTR_NAME_LMA, &size);
+                       if (!rc && unlikely(size < sizeof(*lma))) {
+                               rc = -EINVAL;
+                       } else if (!rc) {

                                lma->lma_incompat =
                                        le32_to_cpu(lma->lma_incompat);
                                lma->lma_incompat |=
                                lma->lma_incompat =
                                        le32_to_cpu(lma->lma_incompat);
                                lma->lma_incompat |=