cluster/distribute: detect stale layouts in entry fops

dht_mkdir ()
{
      first-hashed-subvol = hashed-subvol for "bname" in in-memory
                            layout of "parent";
      inodelk (SETLKW, parent, "LAYOUT_HEAL_DOMAIN", "can be any
               subvol, but we choose first-hashed-subvol randomly");
      {
begin:
            hashed-subvol = hashed-subvol for "bname" in in-memory
                            layout of "parent";
            hash-range = extract hashe-range from layout of "parent";

            ret = mkdir (parent/bname, hashed-subvol, hash-range);
            if (ret == "hash-value doesn't fall into layout stored on
                       the brick (this error is returned by posix-mkdir)")
            {
                refresh_parent_layout ();
                goto begin;
            }

      }
      inodelk (UNLCK, parent, "LAYOUT_HEAL_DOMAIN",
               "first-hashed-subvol");

      proceed with other parts of dht_mkdir;
}

posix_mkdir (parent/bname, client-hash-range)
{

       disk-hash-range = getxattr (parent, "dht-layout-key");
       if (disk-hash-range != client-hash-range) {
              fail-with-error ("hash-value doesn't fall into layout
                                stored on the brick");
              return 0;
       }

       continue-with-posix-mkdir;
}

Similar changes need to be done for dentry operations like create,
symlink, link, unlink, rmdir, rename. These will be addressed in
subsequent patches. This patch addresses only mkdir codepath.

This change breaks stripe tests, as on some striped subvols dht layout
xattrs are not set for some reason. This results in failure of
mkdir. Since striped volumes are always created with dht, some tests
associated with stripe also fail. So, I am making following tests
changes (since stripe is out of maintainance):
* modify ./tests/basic/rpc-coverage.t to not to use striped volumes
* mark all (2) tests in tests/bugs/stripe/ as bad tests

Change-Id: Idd1ae879f24a48303dc743c1bb4d91f89a629e25
BUG: 1323040
Signed-off-by: Raghavendra G <rgowdapp@redhat.com>
Reviewed-on: http://review.gluster.org/13885
Smoke: Gluster Build System <jenkins@build.gluster.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: N Balachandran <nbalacha@redhat.com>

5 files changed, 646 insertions, 27 deletions

diff --git a/xlators/cluster/dht/src/dht-common.c b/xlators/cluster/dht/src/dht-common.c
index 3afbc6258f3..be568063bd2 100644
--- a/xlators/cluster/dht/src/dht-common.c
+++ b/xlators/cluster/dht/src/dht-common.c
@@ -5377,7 +5377,6 @@ out:
         return 0;
 }
 
-
 int32_t
 dht_mknod_do (call_frame_t *frame)
 {
@@ -5562,6 +5561,357 @@ err:
         return -1;
 }
 
+int
+dht_refresh_parent_layout_resume (call_frame_t *frame, xlator_t *this, int ret,
+                                  int invoke_cbk)
+{
+        dht_local_t  *local        = NULL, *parent_local = NULL;
+        call_stub_t  *stub         = NULL;
+        call_frame_t *parent_frame = NULL;
+
+        local = frame->local;
+
+        stub = local->stub;
+        local->stub = NULL;
+
+        parent_frame = stub->frame;
+        parent_local = parent_frame->local;
+
+        if (ret < 0) {
+                parent_local->op_ret = -1;
+                parent_local->op_errno = local->op_errno
+                        ? local->op_errno : EIO;
+        } else {
+                parent_local->op_ret = 0;
+        }
+
+        call_resume (stub);
+
+        DHT_STACK_DESTROY (frame);
+
+        return 0;
+}
+
+
+int
+dht_refresh_parent_layout_done (call_frame_t *frame)
+{
+        dht_local_t *local = NULL;
+        int          ret   = 0;
+
+        local = frame->local;
+
+        if (local->op_ret < 0) {
+                ret = -1;
+                goto resume;
+        }
+
+        dht_layout_set (frame->this, local->loc.inode,
+                        local->selfheal.refreshed_layout);
+
+resume:
+        dht_refresh_parent_layout_resume (frame, frame->this, ret, 1);
+        return 0;
+}
+
+
+int
+dht_handle_parent_layout_change (xlator_t *this, call_stub_t *stub)
+{
+        call_frame_t *refresh_frame = NULL, *frame = NULL;
+        dht_local_t  *refresh_local = NULL, *local = NULL;
+
+        frame = stub->frame;
+        local = frame->local;
+
+        refresh_frame = copy_frame (frame);
+        refresh_local = dht_local_init (refresh_frame, NULL, NULL,
+                                        stub->fop);
+
+        refresh_local->loc.inode = inode_ref (local->loc.parent);
+        gf_uuid_copy (refresh_local->loc.gfid, local->loc.parent->gfid);
+
+        refresh_local->stub = stub;
+
+        refresh_local->refresh_layout_unlock = dht_refresh_parent_layout_resume;
+        refresh_local->refresh_layout_done = dht_refresh_parent_layout_done;
+
+        dht_refresh_layout (refresh_frame);
+        return 0;
+}
+
+int32_t
+dht_unlock_parent_layout_during_entry_fop_done (call_frame_t *frame,
+                                                void *cookie,
+                                                xlator_t *this,
+                                                int32_t op_ret,
+                                                int32_t op_errno,
+                                                dict_t *xdata)
+{
+        dht_local_t *local                   = NULL;
+        char          gfid[GF_UUID_BUF_SIZE] = {0};
+
+        local = frame->local;
+        gf_uuid_unparse (local->lock.locks[0]->loc.inode->gfid, gfid);
+
+        if (op_ret < 0) {
+                gf_msg (this->name, GF_LOG_WARNING, op_errno,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "unlock failed on gfid: %s, stale lock might be left "
+                        "in DHT_LAYOUT_HEAL_DOMAIN", gfid);
+        }
+
+        DHT_STACK_DESTROY (frame);
+        return 0;
+}
+
+int32_t
+dht_unlock_parent_layout_during_entry_fop (call_frame_t *frame)
+{
+        dht_local_t  *local                   = NULL, *lock_local = NULL;
+        call_frame_t *lock_frame              = NULL;
+        char          pgfid[GF_UUID_BUF_SIZE] = {0};
+
+        local = frame->local;
+
+        gf_uuid_unparse (local->loc.parent->gfid, pgfid);
+
+        lock_frame = copy_frame (frame);
+        if (lock_frame == NULL) {
+                gf_msg (frame->this->name, GF_LOG_WARNING, ENOMEM,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "mkdir (%s/%s) (path: %s): "
+                        "copy frame failed", pgfid, local->loc.name,
+                        local->loc.path);
+                goto done;
+        }
+
+        lock_local = mem_get0 (THIS->local_pool);
+        if (lock_local == NULL) {
+                gf_msg (frame->this->name, GF_LOG_WARNING, ENOMEM,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "mkdir (%s/%s) (path: %s): "
+                        "local creation failed", pgfid, local->loc.name,
+                        local->loc.path);
+                goto done;
+        }
+
+        lock_frame->local = lock_local;
+
+        lock_local->lock.locks = local->lock.locks;
+        lock_local->lock.lk_count = local->lock.lk_count;
+
+        local->lock.locks = NULL;
+        local->lock.lk_count = 0;
+
+        dht_unlock_inodelk (lock_frame, lock_local->lock.locks,
+                            lock_local->lock.lk_count,
+                            dht_unlock_parent_layout_during_entry_fop_done);
+
+done:
+        return 0;
+}
+
+int32_t
+dht_guard_parent_layout_during_entry_fop_cbk (call_frame_t *frame, void *cookie,
+                                              xlator_t *this, int32_t op_ret,
+                                              int32_t op_errno, dict_t *xdata)
+{
+        dht_local_t *local = NULL;
+        call_stub_t *stub  = NULL;
+
+        local = frame->local;
+        stub = local->stub;
+        local->stub = NULL;
+
+        if (op_ret < 0) {
+                local->op_ret = -1;
+                local->op_errno = op_errno;
+        } else {
+                local->op_ret = 0;
+        }
+
+        call_resume (stub);
+
+        return 0;
+}
+
+int32_t
+dht_guard_parent_layout_during_entry_fop (xlator_t *subvol, call_stub_t *stub)
+{
+        dht_local_t   *local                  = NULL;
+        int            count                  = 1,    ret = -1;
+        dht_lock_t   **lk_array               = NULL;
+        loc_t         *loc                    = NULL;
+        xlator_t      *hashed_subvol          = NULL, *this = NULL;;
+        call_frame_t  *frame                  = NULL;
+        char          pgfid[GF_UUID_BUF_SIZE] = {0};
+        loc_t          parent                 = {0, };
+        int32_t       *parent_disk_layout     = NULL;
+        dht_layout_t  *parent_layout          = NULL;
+        dht_conf_t    *conf                   = NULL;
+
+        GF_VALIDATE_OR_GOTO ("dht", stub, err);
+
+        frame = stub->frame;
+        this = frame->this;
+
+        conf = this->private;
+
+        local = frame->local;
+
+        local->stub = stub;
+
+        /* TODO: recheck whether we should lock on src or dst if we do similar
+         * stale layout checks for rename.
+         */
+        loc = &stub->args.loc;
+
+        gf_uuid_unparse (loc->parent->gfid, pgfid);
+
+        if (local->params == NULL) {
+                local->params = dict_new ();
+                if (local->params == NULL) {
+                        local->op_errno = ENOMEM;
+                        gf_msg (this->name, GF_LOG_WARNING, local->op_errno,
+                                DHT_MSG_PARENT_LAYOUT_CHANGED,
+                                "%s (%s/%s) (path: %s): "
+                                "dict allocation failed",
+                                gf_fop_list[stub->fop],
+                                pgfid, loc->name, loc->path);
+                        goto err;
+                }
+        }
+
+        hashed_subvol = dht_subvol_get_hashed (this, loc);
+        if (hashed_subvol == NULL) {
+                local->op_errno = EINVAL;
+
+                gf_msg (this->name, GF_LOG_WARNING, local->op_errno,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "%s (%s/%s) (path: %s): "
+                        "hashed subvolume not found", gf_fop_list[stub->fop],
+                        pgfid, loc->name, loc->path);
+                goto err;
+        }
+
+        parent_layout = dht_layout_get (this, loc->parent);
+
+        ret = dht_disk_layout_extract_for_subvol (this, parent_layout,
+                                                  hashed_subvol,
+                                                  &parent_disk_layout);
+        if (ret == -1) {
+                local->op_errno = EINVAL;
+                gf_msg (this->name, GF_LOG_WARNING, local->op_errno,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "%s (%s/%s) (path: %s): "
+                        "extracting in-memory layout of parent failed. ",
+                        gf_fop_list[stub->fop], pgfid, loc->name, loc->path);
+                goto err;
+        }
+
+        memcpy ((void *)local->parent_disk_layout, (void *)parent_disk_layout,
+                sizeof (local->parent_disk_layout));
+
+        dht_layout_unref (this, parent_layout);
+        parent_layout = NULL;
+
+        ret = dict_set_str (local->params, GF_PREOP_PARENT_KEY,
+                            conf->xattr_name);
+        if (ret < 0) {
+                local->op_errno = -ret;
+                gf_msg (this->name, GF_LOG_WARNING, local->op_errno,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "%s (%s/%s) (path: %s): "
+                        "setting %s key in params dictionary failed. ",
+                        gf_fop_list[stub->fop], pgfid, loc->name, loc->path,
+                        GF_PREOP_PARENT_KEY);
+                goto err;
+        }
+
+        ret = dict_set_bin (local->params, conf->xattr_name, parent_disk_layout,
+                            4 * 4);
+        if (ret < 0) {
+                local->op_errno = -ret;
+                gf_msg (this->name, GF_LOG_WARNING, local->op_errno,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "%s (%s/%s) (path: %s): "
+                        "setting parent-layout in params dictionary failed. ",
+                        gf_fop_list[stub->fop], pgfid, loc->name, loc->path);
+                goto err;
+        }
+
+        parent_disk_layout = NULL;
+
+        parent.inode = inode_ref (loc->parent);
+        gf_uuid_copy (parent.gfid, loc->parent->gfid);
+
+        lk_array = GF_CALLOC (count, sizeof (*lk_array), gf_common_mt_char);
+
+        if (lk_array == NULL) {
+                local->op_errno = ENOMEM;
+
+                gf_msg (this->name, GF_LOG_WARNING, local->op_errno,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "%s (%s/%s) (path: %s): "
+                        "calloc failure",
+                        gf_fop_list[stub->fop], pgfid, loc->name, loc->path);
+
+                goto err;
+        }
+
+        lk_array[0] = dht_lock_new (frame->this, hashed_subvol, &parent,
+                                    F_RDLCK, DHT_LAYOUT_HEAL_DOMAIN);
+
+        if (lk_array[0] == NULL) {
+                local->op_errno = ENOMEM;
+                gf_msg (this->name, GF_LOG_WARNING, local->op_errno,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "%s (%s/%s) (path: %s): "
+                        "lock allocation failed",
+                        gf_fop_list[stub->fop], pgfid, loc->name, loc->path);
+
+                goto err;
+        }
+
+        local->lock.locks = lk_array;
+        local->lock.lk_count = count;
+
+        ret = dht_blocking_inodelk (frame, lk_array, count, FAIL_ON_ANY_ERROR,
+                                    dht_guard_parent_layout_during_entry_fop_cbk);
+
+        if (ret < 0) {
+                local->op_errno = EIO;
+                local->lock.locks = NULL;
+                local->lock.lk_count = 0;
+                gf_msg (this->name, GF_LOG_WARNING, local->op_errno,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "%s (%s/%s) (path: %s): "
+                        "dht_blocking_inodelk failed",
+                        gf_fop_list[stub->fop], pgfid, loc->name, loc->path);
+
+                goto err;
+        }
+
+        loc_wipe (&parent);
+
+        return 0;
+err:
+        if (lk_array != NULL) {
+                dht_lock_array_free (lk_array, count);
+                GF_FREE (lk_array);
+        }
+
+        loc_wipe (&parent);
+
+        if (parent_disk_layout != NULL)
+                GF_FREE (parent_disk_layout);
+
+        if (parent_layout != NULL)
+                dht_layout_unref (this, parent_layout);
+
+        return -1;
+}
 
 int
 dht_mknod (call_frame_t *frame, xlator_t *this,
@@ -6690,15 +7040,154 @@ dht_mkdir_hashed_cbk (call_frame_t *frame, void *cookie,
                       xlator_t *this, int op_ret, int op_errno,
                       inode_t *inode, struct iatt *stbuf,
                       struct iatt *preparent, struct iatt *postparent,
+                      dict_t *xdata);
+
+int
+dht_mkdir_helper (call_frame_t *frame, xlator_t *this,
+                  loc_t *loc, mode_t mode, mode_t umask, dict_t *params)
+{
+        dht_local_t  *local                   = NULL;
+        dht_conf_t   *conf                    = NULL;
+        int           op_errno                = -1, ret = -1;
+        xlator_t     *hashed_subvol           = NULL;
+        int32_t      *parent_disk_layout      = NULL;
+        dht_layout_t *parent_layout           = NULL;
+        char          pgfid[GF_UUID_BUF_SIZE] = {0};
+
+        VALIDATE_OR_GOTO (frame, err);
+        VALIDATE_OR_GOTO (this, err);
+        VALIDATE_OR_GOTO (loc, err);
+        VALIDATE_OR_GOTO (loc->inode, err);
+        VALIDATE_OR_GOTO (loc->path, err);
+        VALIDATE_OR_GOTO (this->private, err);
+
+        gf_uuid_unparse (loc->parent->gfid, pgfid);
+
+        conf = this->private;
+        local = frame->local;
+
+        if (local->op_ret == -1) {
+                gf_msg (this->name, GF_LOG_WARNING, local->op_errno,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "mkdir (%s/%s) (path: %s): refreshing parent layout "
+                        "failed.", pgfid, loc->name,
+                        loc->path);
+
+                op_errno = local->op_errno;
+                goto err;
+        }
+
+        local->op_ret = -1;
+
+        hashed_subvol = dht_subvol_get_hashed (this, loc);
+        if (hashed_subvol == NULL) {
+                gf_msg_debug (this->name, 0,
+                              "mkdir (%s/%s) (path: %s): hashed subvol not "
+                              "found", pgfid, loc->name, loc->path);
+                op_errno = ENOENT;
+                goto err;
+        }
+
+        local->hashed_subvol = hashed_subvol;
+
+        parent_layout = dht_layout_get (this, loc->parent);
+
+        ret = dht_disk_layout_extract_for_subvol (this, parent_layout,
+                                                  hashed_subvol,
+                                                  &parent_disk_layout);
+        if (ret == -1) {
+                gf_msg (this->name, GF_LOG_WARNING, EIO,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "mkdir (%s/%s) (path: %s): "
+                        "extracting in-memory layout of parent failed. ",
+                        pgfid, loc->name, loc->path);
+                goto err;
+        }
+
+        if (memcmp (local->parent_disk_layout, parent_disk_layout,
+                    sizeof (local->parent_disk_layout)) == 0) {
+                gf_msg (this->name, GF_LOG_WARNING, EIO,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "mkdir (%s/%s) (path: %s): loop detected. "
+                        "parent layout didn't change even though "
+                        "previous attempt of mkdir failed because of "
+                        "in-memory layout not matching with that on disk.",
+                        pgfid, loc->name, loc->path);
+                op_errno = EIO;
+                goto err;
+        }
+
+        memcpy ((void *)local->parent_disk_layout, (void *)parent_disk_layout,
+                sizeof (local->parent_disk_layout));
+
+        dht_layout_unref (this, parent_layout);
+        parent_layout = NULL;
+
+        ret = dict_set_str (params, GF_PREOP_PARENT_KEY, conf->xattr_name);
+        if (ret < 0) {
+                local->op_errno = -ret;
+                gf_msg (this->name, GF_LOG_WARNING, local->op_errno,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "mkdir (%s/%s) (path: %s): "
+                        "setting %s key in params dictionary failed. ",
+                        pgfid, loc->name, loc->path, GF_PREOP_PARENT_KEY);
+                goto err;
+        }
+
+        ret = dict_set_bin (params, conf->xattr_name, parent_disk_layout,
+                            4 * 4);
+        if (ret < 0) {
+                local->op_errno = -ret;
+                gf_msg (this->name, GF_LOG_WARNING, local->op_errno,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "setting parent-layout in params dictionary failed. "
+                        "mkdir (%s/%s) (path: %s)", pgfid, loc->name,
+                        loc->path);
+                goto err;
+        }
+
+        parent_disk_layout = NULL;
+
+        STACK_WIND (frame, dht_mkdir_hashed_cbk,
+                    hashed_subvol,
+                    hashed_subvol->fops->mkdir,
+                    loc, mode, umask, params);
+
+        return 0;
+
+err:
+        dht_unlock_parent_layout_during_entry_fop (frame);
+
+        op_errno = local ? local->op_errno : op_errno;
+        DHT_STACK_UNWIND (mkdir, frame, -1, op_errno, NULL, NULL, NULL,
+                          NULL, NULL);
+
+        if (parent_disk_layout != NULL)
+                GF_FREE (parent_disk_layout);
+
+        if (parent_layout != NULL)
+                dht_layout_unref (this, parent_layout);
+
+        return 0;
+}
+
+int
+dht_mkdir_hashed_cbk (call_frame_t *frame, void *cookie,
+                      xlator_t *this, int op_ret, int op_errno,
+                      inode_t *inode, struct iatt *stbuf,
+                      struct iatt *preparent, struct iatt *postparent,
                       dict_t *xdata)
 {
-        dht_local_t  *local = NULL;
-        int           ret = -1;
-        call_frame_t *prev = NULL;
-        dht_layout_t *layout = NULL;
-        dht_conf_t   *conf = NULL;
-        int           i = 0;
-        xlator_t     *hashed_subvol = NULL;
+        dht_local_t  *local                   = NULL;
+        int           ret                     = -1;
+        call_frame_t *prev                    = NULL;
+        dht_layout_t *layout                  = NULL;
+        dht_conf_t   *conf                    = NULL;
+        int           i                       = 0;
+        xlator_t     *hashed_subvol           = NULL;
+        char          pgfid[GF_UUID_BUF_SIZE] = {0};
+        gf_boolean_t  parent_layout_changed   = _gf_false;
+        call_stub_t  *stub                    = NULL;
 
         VALIDATE_OR_GOTO (this->private, err);
 
@@ -6708,9 +7197,44 @@ dht_mkdir_hashed_cbk (call_frame_t *frame, void *cookie,
         conf = this->private;
         hashed_subvol = local->hashed_subvol;
 
+        gf_uuid_unparse (local->loc.parent->gfid, pgfid);
+
         if (gf_uuid_is_null (local->loc.gfid) && !op_ret)
                 gf_uuid_copy (local->loc.gfid, stbuf->ia_gfid);
 
+        if (op_ret == -1) {
+                local->op_errno = op_errno;
+
+                parent_layout_changed = dict_get (xdata, GF_PREOP_CHECK_FAILED)
+                        ? 1 : 0;
+                if (parent_layout_changed) {
+                        gf_msg (this->name, GF_LOG_INFO, 0,
+                                DHT_MSG_PARENT_LAYOUT_CHANGED,
+                                "mkdir (%s/%s) (path: %s): parent layout "
+                                "changed. Attempting a refresh and then a "
+                                "retry", pgfid, local->loc.name,
+                                local->loc.path);
+
+                        stub = fop_mkdir_stub (frame, dht_mkdir_helper,
+                                               &local->loc, local->mode,
+                                               local->umask, local->params);
+                        if (stub == NULL) {
+                                goto err;
+                        }
+
+                        dht_handle_parent_layout_change (this, stub);
+                        stub = NULL;
+
+                        return 0;
+                }
+
+                goto err;
+        }
+
+        dht_unlock_parent_layout_during_entry_fop (frame);
+        dict_del (local->params, GF_PREOP_PARENT_KEY);
+        dict_del (local->params, conf->xattr_name);
+
         if (dht_is_subvol_filled (this, hashed_subvol))
                 ret = dht_layout_merge (this, layout, prev->this,
                                         -1, ENOSPC, NULL);
@@ -6726,10 +7250,6 @@ dht_mkdir_hashed_cbk (call_frame_t *frame, void *cookie,
                         "%s: failed to merge layouts for subvol %s",
                         local->loc.path, prev->this->name);
 
-        if (op_ret == -1) {
-                local->op_errno = op_errno;
-                goto err;
-        }
         local->op_ret = 0;
 
         dht_iatt_merge (this, &local->stbuf, stbuf, prev->this);
@@ -6744,6 +7264,7 @@ dht_mkdir_hashed_cbk (call_frame_t *frame, void *cookie,
                 dht_selfheal_directory (frame, dht_mkdir_selfheal_cbk,
                                         &local->loc, layout);
         }
+
         for (i = 0; i < conf->subvolume_cnt; i++) {
                 if (conf->subvolumes[i] == hashed_subvol)
                         continue;
@@ -6754,21 +7275,64 @@ dht_mkdir_hashed_cbk (call_frame_t *frame, void *cookie,
         }
         return 0;
 err:
+        if (local->op_ret != 0)
+                dht_unlock_parent_layout_during_entry_fop (frame);
+
         DHT_STACK_UNWIND (mkdir, frame, -1, op_errno, NULL, NULL, NULL,
                           NULL, NULL);
+        if (stub) {
+                call_stub_destroy (stub);
+        }
+
         return 0;
 }
 
+int
+dht_mkdir_guard_parent_layout_cbk (call_frame_t *frame, xlator_t *this,
+                                   loc_t *loc, mode_t mode, mode_t umask,
+                                   dict_t *params)
+{
+        dht_local_t *local                    = NULL;
+        char          pgfid[GF_UUID_BUF_SIZE] = {0};
+
+        local = frame->local;
+
+        gf_uuid_unparse (loc->parent->gfid, pgfid);
+
+        if (local->op_ret < 0) {
+                gf_msg (this->name, GF_LOG_WARNING, local->op_errno,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "mkdir (%s/%s) (path: %s): "
+                        "Acquiring lock on parent to guard against "
+                        "layout-change failed.", pgfid, loc->name, loc->path);
+                goto err;
+        }
+
+        local->op_ret = -1;
+
+        STACK_WIND (frame, dht_mkdir_hashed_cbk,
+                    local->hashed_subvol,
+                    local->hashed_subvol->fops->mkdir,
+                    loc, mode, umask, params);
+
+        return 0;
+err:
+        DHT_STACK_UNWIND (mkdir, frame, -1, local->op_errno, NULL, NULL, NULL,
+                          NULL, NULL);
+
+        return 0;
+}
 
 int
 dht_mkdir (call_frame_t *frame, xlator_t *this,
            loc_t *loc, mode_t mode, mode_t umask, dict_t *params)
 {
-        dht_local_t  *local  = NULL;
-        dht_conf_t   *conf = NULL;
-        int           op_errno = -1;
-        xlator_t     *hashed_subvol = NULL;
-
+        dht_local_t  *local                   = NULL;
+        dht_conf_t   *conf                    = NULL;
+        int           op_errno                = -1, ret = -1;
+        xlator_t     *hashed_subvol           = NULL;
+        char          pgfid[GF_UUID_BUF_SIZE] = {0};
+        call_stub_t  *stub                    = NULL;
 
         VALIDATE_OR_GOTO (frame, err);
         VALIDATE_OR_GOTO (this, err);
@@ -6777,6 +7341,8 @@ dht_mkdir (call_frame_t *frame, xlator_t *this,
         VALIDATE_OR_GOTO (loc->path, err);
         VALIDATE_OR_GOTO (this->private, err);
 
+        gf_uuid_unparse (loc->parent->gfid, pgfid);
+
         conf = this->private;
 
         dht_get_du_info (frame, this, loc);
@@ -6792,14 +7358,17 @@ dht_mkdir (call_frame_t *frame, xlator_t *this,
                 gf_msg_debug (this->name, 0,
                               "hashed subvol not found for %s",
                               loc->path);
-                op_errno = EIO;
+                local->op_errno = EIO;
                 goto err;
         }
 
+
         local->hashed_subvol = hashed_subvol;
         local->mode = mode;
         local->umask = umask;
-        local->params = dict_ref (params);
+        if (params)
+                local->params = dict_ref (params);
+
         local->inode  = inode_ref (loc->inode);
 
         local->layout = dht_layout_new (this, conf->subvolume_cnt);
@@ -6818,15 +7387,31 @@ dht_mkdir (call_frame_t *frame, xlator_t *this,
         else
                 local->layout->commit_hash = DHT_LAYOUT_HASH_INVALID;
 
-        STACK_WIND (frame, dht_mkdir_hashed_cbk,
-                    hashed_subvol,
-                    hashed_subvol->fops->mkdir,
-                    loc, mode, umask, params);
+
+        stub = fop_mkdir_stub (frame, dht_mkdir_guard_parent_layout_cbk, loc,
+                               mode, umask, params);
+        if (stub == NULL) {
+                gf_msg (this->name, GF_LOG_WARNING, ENOMEM,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "mkdir (%s/%s) (path: %s): "
+                        "creating stub failed.", pgfid, loc->name, loc->path);
+                local->op_errno = ENOMEM;
+                goto err;
+        }
+
+        ret = dht_guard_parent_layout_during_entry_fop (this, stub);
+        if (ret < 0) {
+                gf_msg (this->name, GF_LOG_WARNING, 0,
+                        DHT_MSG_PARENT_LAYOUT_CHANGED,
+                        "mkdir (%s/%s) (path: %s) cannot wind lock request to "
+                        "guard parent layout", pgfid, loc->name, loc->path);
+                goto err;
+        }
 
         return 0;
 
 err:
-        op_errno = (op_errno == -1) ? errno : op_errno;
+        op_errno = local ? local->op_errno : op_errno;
         DHT_STACK_UNWIND (mkdir, frame, -1, op_errno, NULL, NULL, NULL,
                           NULL, NULL);
 
diff --git a/xlators/cluster/dht/src/dht-common.h b/xlators/cluster/dht/src/dht-common.h
index b63ee65acfb..7cc549e133c 100644
--- a/xlators/cluster/dht/src/dht-common.h
+++ b/xlators/cluster/dht/src/dht-common.h
@@ -13,6 +13,7 @@
 
 #include "dht-mem-types.h"
 #include "dht-messages.h"
+#include "call-stub.h"
 #include "libxlator.h"
 #include "syncop.h"
 #include "refcount.h"
@@ -281,6 +282,9 @@ struct dht_local {
                 int                 op_ret;
                 int                 op_errno;
         } lock;
+
+        call_stub_t *stub;
+        int32_t      parent_disk_layout[4];
 };
 typedef struct dht_local dht_local_t;
 
@@ -705,7 +709,9 @@ int     dht_disk_layout_extract (xlator_t *this, dht_layout_t *layout,
                              int       pos, int32_t **disk_layout_p);
 int dht_disk_layout_merge (xlator_t   *this, dht_layout_t *layout,
                            int         pos, void *disk_layout_raw, int disk_layout_len);
-
+int
+dht_disk_layout_extract_for_subvol (xlator_t *this, dht_layout_t *layout,
+                                    xlator_t *subvol, int32_t **disk_layout_p);
 
 int dht_frame_return (call_frame_t *frame);
 
diff --git a/xlators/cluster/dht/src/dht-helper.c b/xlators/cluster/dht/src/dht-helper.c
index 8673c1fd83a..0384c2a4cc4 100644
--- a/xlators/cluster/dht/src/dht-helper.c
+++ b/xlators/cluster/dht/src/dht-helper.c
@@ -621,6 +621,11 @@ dht_local_wipe (xlator_t *this, dht_local_t *local)
         if (local->rebalance.iobref)
                 iobref_unref (local->rebalance.iobref);
 
+        if (local->stub) {
+                call_stub_destroy (local->stub);
+                local->stub = NULL;
+        }
+
         mem_put (local);
 }
 
diff --git a/xlators/cluster/dht/src/dht-layout.c b/xlators/cluster/dht/src/dht-layout.c
index ca600e9618a..4352ffe5756 100644
--- a/xlators/cluster/dht/src/dht-layout.c
+++ b/xlators/cluster/dht/src/dht-layout.c
@@ -280,6 +280,22 @@ out:
         return ret;
 }
 
+int
+dht_disk_layout_extract_for_subvol (xlator_t *this, dht_layout_t *layout,
+                                    xlator_t *subvol, int32_t **disk_layout_p)
+{
+        int i = 0;
+
+        for (i = 0; i < layout->cnt; i++) {
+                if (layout->list[i].xlator == subvol)
+                        break;
+        }
+
+        if (i == layout->cnt)
+                return -1;
+
+        return dht_disk_layout_extract (this, layout, i, disk_layout_p);
+}
 
 int
 dht_disk_layout_merge (xlator_t *this, dht_layout_t *layout,
diff --git a/xlators/cluster/dht/src/dht-messages.h b/xlators/cluster/dht/src/dht-messages.h
index 4403efc151c..ebad3d1ced9 100644
--- a/xlators/cluster/dht/src/dht-messages.h
+++ b/xlators/cluster/dht/src/dht-messages.h
@@ -40,7 +40,7 @@
  */
 
 #define GLFS_DHT_BASE                   GLFS_MSGID_COMP_DHT
-#define GLFS_DHT_NUM_MESSAGES           113
+#define GLFS_DHT_NUM_MESSAGES           114
 #define GLFS_MSGID_END          (GLFS_DHT_BASE + GLFS_DHT_NUM_MESSAGES + 1)
 
 /* Messages with message IDs */
@@ -1043,12 +1043,19 @@
 #define DHT_MSG_FD_CTX_SET_FAILED         (GLFS_DHT_BASE + 112)
 
 /*
- * @messageid 109112
+ * @messageid 109113
  * @diagnosis
  * @recommendedaction None
  */
 
 #define DHT_MSG_STALE_LOOKUP                    (GLFS_DHT_BASE + 113)
 
+/*
+ * @messageid 109114
+ * @diagnosis
+ * @recommendedaction None
+ */
+#define DHT_MSG_PARENT_LAYOUT_CHANGED  (GLFS_DHT_BASE + 114)
+
 #define glfs_msg_end_x GLFS_MSGID_END, "Invalid: End of messages"
 #endif /* _DHT_MESSAGES_H_ */