LU-11502 migrate: link parents lock may deadlock

[fs/lustre-release.git] / lustre / mdt / mdt_reint.c

diff --git a/lustre/mdt/mdt_reint.c b/lustre/mdt/mdt_reint.c
index b1809dd..0e3b46b 100644 (file)
--- a/lustre/mdt/mdt_reint.c
+++ b/lustre/mdt/mdt_reint.c
@@ -1376,6 +1376,21 @@ static void mdt_unlock_list(struct mdt_thread_info *info,
        }
 }
 
+static inline void mdt_migrate_object_unlock(struct mdt_thread_info *info,
+                                            struct mdt_object *obj,
+                                            struct mdt_lock_handle *lh,
+                                            struct ldlm_enqueue_info *einfo,
+                                            struct list_head *slave_locks,
+                                            int decref)
+{
+       if (mdt_object_remote(obj)) {
+               mdt_unlock_list(info, slave_locks, decref);
+               mdt_object_unlock(info, obj, lh, decref);
+       } else {
+               mdt_reint_striped_unlock(info, obj, lh, einfo, decref);
+       }
+}
+
 /*
  * lock parents of links, and also check whether total locks don't exceed
  * RS_MAX_LOCKS.
@@ -1384,18 +1399,20 @@ static void mdt_unlock_list(struct mdt_thread_info *info,
  * \retval     1 on success, but total lock count may exceed RS_MAX_LOCKS
  * \retval     -ev negative errno upon error
  */
-static int mdt_lock_links(struct mdt_thread_info *info,
-                         struct mdt_object *pobj,
-                         const struct md_attr *ma,
-                         struct mdt_object *obj,
-                         struct list_head *link_locks)
+static int mdt_link_parents_lock(struct mdt_thread_info *info,
+                                struct mdt_object *pobj,
+                                const struct md_attr *ma,
+                                struct mdt_object *obj,
+                                struct mdt_lock_handle *lhp,
+                                struct ldlm_enqueue_info *peinfo,
+                                struct list_head *parent_slave_locks,
+                                struct list_head *link_locks)
 {
        struct mdt_device *mdt = info->mti_mdt;
        struct lu_buf *buf = &info->mti_big_buf;
        struct lu_name *lname = &info->mti_name;
        struct linkea_data ldata = { NULL };
        bool blocked = false;
-       int retries = 5;
        int local_lnkp_cnt = 0;
        int rc;
 
@@ -1416,7 +1433,6 @@ static int mdt_lock_links(struct mdt_thread_info *info,
                RETURN(rc);
        }
 
-repeat:
        for (linkea_first_entry(&ldata); ldata.ld_lee && !rc;
             linkea_next_entry(&ldata)) {
                struct mdt_object *lnkp;
@@ -1519,12 +1535,19 @@ repeat:
                rc = mdt_object_lock_try(info, lnkp, &msl->msl_lh, &ibits,
                                         MDS_INODELOCK_UPDATE, true);
                if (!(ibits & MDS_INODELOCK_UPDATE)) {
-                       blocked = true;
 
-                       CDEBUG(D_INFO, "busy lock on "DFID" "DNAME" retry %d\n",
-                              PFID(&fid), PNAME(lname), retries);
+                       CDEBUG(D_INFO, "busy lock on "DFID" "DNAME"\n",
+                              PFID(&fid), PNAME(lname));
 
                        mdt_unlock_list(info, link_locks, 1);
+                       /* also unlock parent locks to avoid deadlock */
+                       if (!blocked)
+                               mdt_migrate_object_unlock(info, pobj, lhp,
+                                                         peinfo,
+                                                         parent_slave_locks,
+                                                         1);
+
+                       blocked = true;
 
                        mdt_lock_pdo_init(&msl->msl_lh, LCK_PW, lname);
                        rc = mdt_object_lock(info, lnkp, &msl->msl_lh,
@@ -1565,15 +1588,8 @@ repeat:
                rc = mdt_revoke_remote_lookup_lock(info, lnkp, obj);
        }
 
-       if (blocked) {
-               rc = -EBUSY;
-               if (--retries > 0) {
-                       mdt_unlock_list(info, link_locks, rc);
-                       blocked = false;
-                       local_lnkp_cnt = 0;
-                       goto repeat;
-               }
-       }
+       if (blocked)
+               GOTO(out, rc = -EBUSY);
 
        EXIT;
 out:
@@ -1648,21 +1664,6 @@ out:
        return rc;
 }
 
-static inline void mdt_migrate_object_unlock(struct mdt_thread_info *info,
-                                            struct mdt_object *obj,
-                                            struct mdt_lock_handle *lh,
-                                            struct ldlm_enqueue_info *einfo,
-                                            struct list_head *slave_locks,
-                                            int decref)
-{
-       if (mdt_object_remote(obj)) {
-               mdt_unlock_list(info, slave_locks, decref);
-               mdt_object_unlock(info, obj, lh, decref);
-       } else {
-               mdt_reint_striped_unlock(info, obj, lh, einfo, decref);
-       }
-}
-
 /* lock parent and its stripes */
 static int mdt_migrate_parent_lock(struct mdt_thread_info *info,
                                   struct mdt_object *obj,
@@ -1951,6 +1952,7 @@ static int mdt_reint_migrate_internal(struct mdt_thread_info *info)
        LIST_HEAD(parent_slave_locks);
        LIST_HEAD(child_slave_locks);
        LIST_HEAD(link_locks);
+       int lock_retries = 5;
        bool open_sem_locked = false;
        bool do_sync = false;
        int rc;
@@ -1990,6 +1992,7 @@ static int mdt_reint_migrate_internal(struct mdt_thread_info *info)
        if (rc)
                GOTO(put_parent, rc);
 
+lock_parent:
        /* lock parent object */
        lhp = &info->mti_lh[MDT_LH_PARENT];
        mdt_lock_reg_init(lhp, LCK_PW);
@@ -2008,7 +2011,14 @@ static int mdt_reint_migrate_internal(struct mdt_thread_info *info)
                GOTO(unlock_parent, rc);
 
        /* lock parents of source links, and revoke LOOKUP lock of links */
-       rc = mdt_lock_links(info, pobj, ma, sobj, &link_locks);
+       rc = mdt_link_parents_lock(info, pobj, ma, sobj, lhp, peinfo,
+                                  &parent_slave_locks, &link_locks);
+       if (rc == -EBUSY && lock_retries-- > 0) {
+               mdt_object_put(env, sobj);
+               mdt_object_put(env, spobj);
+               goto lock_parent;
+       }
+
        if (rc < 0)
                GOTO(put_source, rc);
 
@@ -2098,7 +2108,7 @@ unlock_open_sem:
        if (open_sem_locked)
                up_write(&sobj->mot_open_sem);
 unlock_links:
-       mdt_unlock_list(info, &link_locks, rc);
+       mdt_unlock_list(info, &link_locks, do_sync ?: rc);
 put_source:
        mdt_object_put(env, sobj);
        mdt_object_put(env, spobj);