]> git.karo-electronics.de Git - linux-beck.git/commitdiff
drbd: RCU for disk_conf
authorPhilipp Reisner <philipp.reisner@linbit.com>
Tue, 3 May 2011 13:00:55 +0000 (15:00 +0200)
committerPhilipp Reisner <philipp.reisner@linbit.com>
Thu, 8 Nov 2012 15:55:43 +0000 (16:55 +0100)
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
drivers/block/drbd/drbd_int.h
drivers/block/drbd/drbd_main.c
drivers/block/drbd/drbd_nl.c
drivers/block/drbd/drbd_receiver.c
drivers/block/drbd/drbd_state.c
drivers/block/drbd/drbd_worker.c

index f8d0ac38685890a284bb530309dd99036d5b782e..cd77dd497b941d3fe52665813a303e5281300ace 100644 (file)
@@ -777,7 +777,7 @@ struct drbd_backing_dev {
        struct block_device *backing_bdev;
        struct block_device *md_bdev;
        struct drbd_md md;
-       struct disk_conf dc; /* The user provided config... */
+       struct disk_conf *disk_conf; /* RCU, for updates: mdev->tconn->conf_update */
        sector_t known_size; /* last known size of that backing device */
 };
 
@@ -1644,8 +1644,13 @@ static inline union drbd_state drbd_read_state(struct drbd_conf *mdev)
 #define __drbd_chk_io_error(m,f) __drbd_chk_io_error_(m,f, __func__)
 static inline void __drbd_chk_io_error_(struct drbd_conf *mdev, int forcedetach, const char *where)
 {
-       switch (mdev->ldev->dc.on_io_error) {
-       case EP_PASS_ON:
+       enum drbd_io_error_p ep;
+
+       rcu_read_lock();
+       ep = rcu_dereference(mdev->ldev->disk_conf)->on_io_error;
+       rcu_read_unlock();
+       switch (ep) {
+       case EP_PASS_ON: /* FIXME would this be better named "Ignore"? */
                if (!forcedetach) {
                        if (__ratelimit(&drbd_ratelimit_state))
                                dev_err(DEV, "Local IO failed in %s.\n", where);
@@ -1694,9 +1699,9 @@ static inline void drbd_chk_io_error_(struct drbd_conf *mdev,
  * BTW, for internal meta data, this happens to be the maximum capacity
  * we could agree upon with our peer node.
  */
-static inline sector_t drbd_md_first_sector(struct drbd_backing_dev *bdev)
+static inline sector_t _drbd_md_first_sector(int meta_dev_idx, struct drbd_backing_dev *bdev)
 {
-       switch (bdev->dc.meta_dev_idx) {
+       switch (meta_dev_idx) {
        case DRBD_MD_INDEX_INTERNAL:
        case DRBD_MD_INDEX_FLEX_INT:
                return bdev->md.md_offset + bdev->md.bm_offset;
@@ -1706,13 +1711,30 @@ static inline sector_t drbd_md_first_sector(struct drbd_backing_dev *bdev)
        }
 }
 
+static inline sector_t drbd_md_first_sector(struct drbd_backing_dev *bdev)
+{
+       int meta_dev_idx;
+
+       rcu_read_lock();
+       meta_dev_idx = rcu_dereference(bdev->disk_conf)->meta_dev_idx;
+       rcu_read_unlock();
+
+       return _drbd_md_first_sector(meta_dev_idx, bdev);
+}
+
 /**
  * drbd_md_last_sector() - Return the last sector number of the meta data area
  * @bdev:      Meta data block device.
  */
 static inline sector_t drbd_md_last_sector(struct drbd_backing_dev *bdev)
 {
-       switch (bdev->dc.meta_dev_idx) {
+       int meta_dev_idx;
+
+       rcu_read_lock();
+       meta_dev_idx = rcu_dereference(bdev->disk_conf)->meta_dev_idx;
+       rcu_read_unlock();
+
+       switch (meta_dev_idx) {
        case DRBD_MD_INDEX_INTERNAL:
        case DRBD_MD_INDEX_FLEX_INT:
                return bdev->md.md_offset + MD_AL_OFFSET - 1;
@@ -1740,12 +1762,18 @@ static inline sector_t drbd_get_capacity(struct block_device *bdev)
 static inline sector_t drbd_get_max_capacity(struct drbd_backing_dev *bdev)
 {
        sector_t s;
-       switch (bdev->dc.meta_dev_idx) {
+       int meta_dev_idx;
+
+       rcu_read_lock();
+       meta_dev_idx = rcu_dereference(bdev->disk_conf)->meta_dev_idx;
+       rcu_read_unlock();
+
+       switch (meta_dev_idx) {
        case DRBD_MD_INDEX_INTERNAL:
        case DRBD_MD_INDEX_FLEX_INT:
                s = drbd_get_capacity(bdev->backing_bdev)
                        ? min_t(sector_t, DRBD_MAX_SECTORS_FLEX,
-                                       drbd_md_first_sector(bdev))
+                               _drbd_md_first_sector(meta_dev_idx, bdev))
                        : 0;
                break;
        case DRBD_MD_INDEX_FLEX_EXT:
@@ -1771,9 +1799,15 @@ static inline sector_t drbd_get_max_capacity(struct drbd_backing_dev *bdev)
 static inline sector_t drbd_md_ss__(struct drbd_conf *mdev,
                                    struct drbd_backing_dev *bdev)
 {
-       switch (bdev->dc.meta_dev_idx) {
+       int meta_dev_idx;
+
+       rcu_read_lock();
+       meta_dev_idx = rcu_dereference(bdev->disk_conf)->meta_dev_idx;
+       rcu_read_unlock();
+
+       switch (meta_dev_idx) {
        default: /* external, some index */
-               return MD_RESERVED_SECT * bdev->dc.meta_dev_idx;
+               return MD_RESERVED_SECT * meta_dev_idx;
        case DRBD_MD_INDEX_INTERNAL:
                /* with drbd08, internal meta data is always "flexible" */
        case DRBD_MD_INDEX_FLEX_INT:
index e37244485d7201e8e7e276017a8c925cdfd17cd9..de6afa75dec658b2df146de0fd5f656653b017a8 100644 (file)
@@ -866,6 +866,7 @@ int drbd_send_sync_param(struct drbd_conf *mdev)
        const int apv = mdev->tconn->agreed_pro_version;
        enum drbd_packet cmd;
        struct net_conf *nc;
+       struct disk_conf *dc;
 
        sock = &mdev->tconn->data;
        p = drbd_prepare_command(mdev, sock);
@@ -887,11 +888,12 @@ int drbd_send_sync_param(struct drbd_conf *mdev)
        memset(p->verify_alg, 0, 2 * SHARED_SECRET_MAX);
 
        if (get_ldev(mdev)) {
-               p->rate = cpu_to_be32(mdev->ldev->dc.resync_rate);
-               p->c_plan_ahead = cpu_to_be32(mdev->ldev->dc.c_plan_ahead);
-               p->c_delay_target = cpu_to_be32(mdev->ldev->dc.c_delay_target);
-               p->c_fill_target = cpu_to_be32(mdev->ldev->dc.c_fill_target);
-               p->c_max_rate = cpu_to_be32(mdev->ldev->dc.c_max_rate);
+               dc = rcu_dereference(mdev->ldev->disk_conf);
+               p->rate = cpu_to_be32(dc->resync_rate);
+               p->c_plan_ahead = cpu_to_be32(dc->c_plan_ahead);
+               p->c_delay_target = cpu_to_be32(dc->c_delay_target);
+               p->c_fill_target = cpu_to_be32(dc->c_fill_target);
+               p->c_max_rate = cpu_to_be32(dc->c_max_rate);
                put_ldev(mdev);
        } else {
                p->rate = cpu_to_be32(DRBD_RATE_DEF);
@@ -1056,7 +1058,9 @@ int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags fl
        if (get_ldev_if_state(mdev, D_NEGOTIATING)) {
                D_ASSERT(mdev->ldev->backing_bdev);
                d_size = drbd_get_max_capacity(mdev->ldev);
-               u_size = mdev->ldev->dc.disk_size;
+               rcu_read_lock();
+               u_size = rcu_dereference(mdev->ldev->disk_conf)->disk_size;
+               rcu_read_unlock();
                q_order_type = drbd_queue_order_type(mdev);
                max_bio_size = queue_max_hw_sectors(mdev->ldev->backing_bdev->bd_disk->queue) << 9;
                max_bio_size = min_t(int, max_bio_size, DRBD_MAX_BIO_SIZE);
@@ -2889,7 +2893,6 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
        for (i = UI_CURRENT; i < UI_SIZE; i++)
                bdev->md.uuid[i] = be64_to_cpu(buffer->uuid[i]);
        bdev->md.flags = be32_to_cpu(buffer->flags);
-       bdev->dc.al_extents = be32_to_cpu(buffer->al_nr_extents);
        bdev->md.device_uuid = be64_to_cpu(buffer->device_uuid);
 
        spin_lock_irq(&mdev->tconn->req_lock);
@@ -2901,8 +2904,12 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
        }
        spin_unlock_irq(&mdev->tconn->req_lock);
 
-       if (bdev->dc.al_extents < 7)
-               bdev->dc.al_extents = 127;
+       mutex_lock(&mdev->tconn->conf_update);
+       /* This blocks wants to be get removed... */
+       bdev->disk_conf->al_extents = be32_to_cpu(buffer->al_nr_extents);
+       if (bdev->disk_conf->al_extents < DRBD_AL_EXTENTS_MIN)
+               bdev->disk_conf->al_extents = DRBD_AL_EXTENTS_DEF;
+       mutex_unlock(&mdev->tconn->conf_update);
 
  err:
        mutex_unlock(&mdev->md_io_mutex);
index b8ea4807c981a661d5b2733064bac2964074e6f3..ea62838e0794f24f6349123d199f87b57795acdb 100644 (file)
@@ -384,7 +384,8 @@ static enum drbd_fencing_p highest_fencing_policy(struct drbd_tconn *tconn)
        rcu_read_lock();
        idr_for_each_entry(&tconn->volumes, mdev, vnr) {
                if (get_ldev_if_state(mdev, D_CONSISTENT)) {
-                       fp = max_t(enum drbd_fencing_p, fp, mdev->ldev->dc.fencing);
+                       fp = max_t(enum drbd_fencing_p, fp,
+                                  rcu_dereference(mdev->ldev->disk_conf)->fencing);
                        put_ldev(mdev);
                }
        }
@@ -678,7 +679,12 @@ static void drbd_md_set_sector_offsets(struct drbd_conf *mdev,
                                       struct drbd_backing_dev *bdev)
 {
        sector_t md_size_sect = 0;
-       switch (bdev->dc.meta_dev_idx) {
+       int meta_dev_idx;
+
+       rcu_read_lock();
+       meta_dev_idx = rcu_dereference(bdev->disk_conf)->meta_dev_idx;
+
+       switch (meta_dev_idx) {
        default:
                /* v07 style fixed size indexed meta data */
                bdev->md.md_size_sect = MD_RESERVED_SECT;
@@ -713,6 +719,7 @@ static void drbd_md_set_sector_offsets(struct drbd_conf *mdev,
                bdev->md.bm_offset   = -md_size_sect + MD_AL_OFFSET;
                break;
        }
+       rcu_read_unlock();
 }
 
 /* input size is expected to be in KB */
@@ -803,7 +810,9 @@ enum determine_dev_size drbd_determine_dev_size(struct drbd_conf *mdev, enum dds
        /* TODO: should only be some assert here, not (re)init... */
        drbd_md_set_sector_offsets(mdev, mdev->ldev);
 
-       u_size = mdev->ldev->dc.disk_size;
+       rcu_read_lock();
+       u_size = rcu_dereference(mdev->ldev->disk_conf)->disk_size;
+       rcu_read_unlock();
        size = drbd_new_dev_size(mdev, mdev->ldev, u_size, flags & DDSF_FORCED);
 
        if (drbd_get_capacity(mdev->this_bdev) != size ||
@@ -979,7 +988,9 @@ static void drbd_setup_queue_param(struct drbd_conf *mdev, unsigned int max_bio_
                struct request_queue * const b = mdev->ldev->backing_bdev->bd_disk->queue;
 
                max_hw_sectors = min(queue_max_hw_sectors(b), max_bio_size >> 9);
-               max_segments = mdev->ldev->dc.max_bio_bvecs;
+               rcu_read_lock();
+               max_segments = rcu_dereference(mdev->ldev->disk_conf)->max_bio_bvecs;
+               rcu_read_unlock();
                put_ldev(mdev);
        }
 
@@ -1095,7 +1106,7 @@ int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info)
 {
        enum drbd_ret_code retcode;
        struct drbd_conf *mdev;
-       struct disk_conf *new_disk_conf;
+       struct disk_conf *new_disk_conf, *old_disk_conf;
        int err, fifo_size;
        int *rs_plan_s = NULL;
 
@@ -1114,19 +1125,15 @@ int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info)
                goto out;
        }
 
-/* FIXME freeze IO, cluster wide.
- *
- * We should make sure no-one uses
- * some half-updated struct when we
- * assign it later. */
-
-       new_disk_conf = kmalloc(sizeof(*new_disk_conf), GFP_KERNEL);
+       new_disk_conf = kmalloc(sizeof(struct disk_conf), GFP_KERNEL);
        if (!new_disk_conf) {
                retcode = ERR_NOMEM;
                goto fail;
        }
 
-       memcpy(new_disk_conf, &mdev->ldev->dc, sizeof(*new_disk_conf));
+       mutex_lock(&mdev->tconn->conf_update);
+       old_disk_conf = mdev->ldev->disk_conf;
+       *new_disk_conf = *old_disk_conf;
        if (should_set_defaults(info))
                set_disk_conf_defaults(new_disk_conf);
 
@@ -1151,7 +1158,7 @@ int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info)
                if (!rs_plan_s) {
                        dev_err(DEV, "kmalloc of fifo_buffer failed");
                        retcode = ERR_NOMEM;
-                       goto fail;
+                       goto fail_unlock;
                }
        }
 
@@ -1171,31 +1178,37 @@ int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info)
 
        if (err) {
                retcode = ERR_NOMEM;
-               goto fail;
+               goto fail_unlock;
        }
 
-       /* FIXME
-        * To avoid someone looking at a half-updated struct, we probably
-        * should have a rw-semaphor on net_conf and disk_conf.
-        */
        write_lock_irq(&global_state_lock);
        retcode = drbd_sync_after_valid(mdev, new_disk_conf->resync_after);
        if (retcode == NO_ERROR) {
-               mdev->ldev->dc = *new_disk_conf;
+               rcu_assign_pointer(mdev->ldev->disk_conf, new_disk_conf);
                drbd_sync_after_changed(mdev);
        }
        write_unlock_irq(&global_state_lock);
 
-       drbd_md_sync(mdev);
+       if (retcode != NO_ERROR)
+               goto fail_unlock;
 
+       drbd_md_sync(mdev);
 
        if (mdev->state.conn >= C_CONNECTED)
                drbd_send_sync_param(mdev);
 
+       mutex_unlock(&mdev->tconn->conf_update);
+       synchronize_rcu();
+       kfree(old_disk_conf);
+       goto success;
+
+fail_unlock:
+       mutex_unlock(&mdev->tconn->conf_update);
  fail:
-       put_ldev(mdev);
        kfree(new_disk_conf);
        kfree(rs_plan_s);
+success:
+       put_ldev(mdev);
  out:
        drbd_adm_finish(info, retcode);
        return 0;
@@ -1210,6 +1223,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
        sector_t max_possible_sectors;
        sector_t min_md_device_sectors;
        struct drbd_backing_dev *nbc = NULL; /* new_backing_conf */
+       struct disk_conf *new_disk_conf = NULL;
        struct block_device *bdev;
        struct lru_cache *resync_lru = NULL;
        union drbd_state ns, os;
@@ -1243,17 +1257,22 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
                retcode = ERR_NOMEM;
                goto fail;
        }
+       new_disk_conf = kzalloc(sizeof(struct disk_conf), GFP_KERNEL);
+       if (!new_disk_conf) {
+               retcode = ERR_NOMEM;
+               goto fail;
+       }
+       nbc->disk_conf = new_disk_conf;
 
-       set_disk_conf_defaults(&nbc->dc);
-
-       err = disk_conf_from_attrs(&nbc->dc, info);
+       set_disk_conf_defaults(new_disk_conf);
+       err = disk_conf_from_attrs(new_disk_conf, info);
        if (err) {
                retcode = ERR_MANDATORY_TAG;
                drbd_msg_put_info(from_attrs_err_to_txt(err));
                goto fail;
        }
 
-       if (nbc->dc.meta_dev_idx < DRBD_MD_INDEX_FLEX_INT) {
+       if (new_disk_conf->meta_dev_idx < DRBD_MD_INDEX_FLEX_INT) {
                retcode = ERR_MD_IDX_INVALID;
                goto fail;
        }
@@ -1261,7 +1280,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
        rcu_read_lock();
        nc = rcu_dereference(mdev->tconn->net_conf);
        if (nc) {
-               if (nbc->dc.fencing == FP_STONITH && nc->wire_protocol == DRBD_PROT_A) {
+               if (new_disk_conf->fencing == FP_STONITH && nc->wire_protocol == DRBD_PROT_A) {
                        rcu_read_unlock();
                        retcode = ERR_STONITH_AND_PROT_A;
                        goto fail;
@@ -1269,10 +1288,10 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
        }
        rcu_read_unlock();
 
-       bdev = blkdev_get_by_path(nbc->dc.backing_dev,
+       bdev = blkdev_get_by_path(new_disk_conf->backing_dev,
                                  FMODE_READ | FMODE_WRITE | FMODE_EXCL, mdev);
        if (IS_ERR(bdev)) {
-               dev_err(DEV, "open(\"%s\") failed with %ld\n", nbc->dc.backing_dev,
+               dev_err(DEV, "open(\"%s\") failed with %ld\n", new_disk_conf->backing_dev,
                        PTR_ERR(bdev));
                retcode = ERR_OPEN_DISK;
                goto fail;
@@ -1287,12 +1306,12 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
         * should check it for you already; but if you don't, or
         * someone fooled it, we need to double check here)
         */
-       bdev = blkdev_get_by_path(nbc->dc.meta_dev,
+       bdev = blkdev_get_by_path(new_disk_conf->meta_dev,
                                  FMODE_READ | FMODE_WRITE | FMODE_EXCL,
-                                 (nbc->dc.meta_dev_idx < 0) ?
+                                 (new_disk_conf->meta_dev_idx < 0) ?
                                  (void *)mdev : (void *)drbd_m_holder);
        if (IS_ERR(bdev)) {
-               dev_err(DEV, "open(\"%s\") failed with %ld\n", nbc->dc.meta_dev,
+               dev_err(DEV, "open(\"%s\") failed with %ld\n", new_disk_conf->meta_dev,
                        PTR_ERR(bdev));
                retcode = ERR_OPEN_MD_DISK;
                goto fail;
@@ -1300,8 +1319,8 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
        nbc->md_bdev = bdev;
 
        if ((nbc->backing_bdev == nbc->md_bdev) !=
-           (nbc->dc.meta_dev_idx == DRBD_MD_INDEX_INTERNAL ||
-            nbc->dc.meta_dev_idx == DRBD_MD_INDEX_FLEX_INT)) {
+           (new_disk_conf->meta_dev_idx == DRBD_MD_INDEX_INTERNAL ||
+            new_disk_conf->meta_dev_idx == DRBD_MD_INDEX_FLEX_INT)) {
                retcode = ERR_MD_IDX_INVALID;
                goto fail;
        }
@@ -1317,21 +1336,21 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
        /* RT - for drbd_get_max_capacity() DRBD_MD_INDEX_FLEX_INT */
        drbd_md_set_sector_offsets(mdev, nbc);
 
-       if (drbd_get_max_capacity(nbc) < nbc->dc.disk_size) {
+       if (drbd_get_max_capacity(nbc) < new_disk_conf->disk_size) {
                dev_err(DEV, "max capacity %llu smaller than disk size %llu\n",
                        (unsigned long long) drbd_get_max_capacity(nbc),
-                       (unsigned long long) nbc->dc.disk_size);
+                       (unsigned long long) new_disk_conf->disk_size);
                retcode = ERR_DISK_TO_SMALL;
                goto fail;
        }
 
-       if (nbc->dc.meta_dev_idx < 0) {
+       if (new_disk_conf->meta_dev_idx < 0) {
                max_possible_sectors = DRBD_MAX_SECTORS_FLEX;
                /* at least one MB, otherwise it does not make sense */
                min_md_device_sectors = (2<<10);
        } else {
                max_possible_sectors = DRBD_MAX_SECTORS;
-               min_md_device_sectors = MD_RESERVED_SECT * (nbc->dc.meta_dev_idx + 1);
+               min_md_device_sectors = MD_RESERVED_SECT * (new_disk_conf->meta_dev_idx + 1);
        }
 
        if (drbd_get_capacity(nbc->md_bdev) < min_md_device_sectors) {
@@ -1356,7 +1375,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
                dev_warn(DEV, "==> truncating very big lower level device "
                        "to currently maximum possible %llu sectors <==\n",
                        (unsigned long long) max_possible_sectors);
-               if (nbc->dc.meta_dev_idx >= 0)
+               if (new_disk_conf->meta_dev_idx >= 0)
                        dev_warn(DEV, "==>> using internal or flexible "
                                      "meta data may help <<==\n");
        }
@@ -1399,14 +1418,14 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
        }
 
        /* Since we are diskless, fix the activity log first... */
-       if (drbd_check_al_size(mdev, &nbc->dc)) {
+       if (drbd_check_al_size(mdev, new_disk_conf)) {
                retcode = ERR_NOMEM;
                goto force_diskless_dec;
        }
 
        /* Prevent shrinking of consistent devices ! */
        if (drbd_md_test_flag(nbc, MDF_CONSISTENT) &&
-           drbd_new_dev_size(mdev, nbc, nbc->dc.disk_size, 0) < nbc->md.la_size_sect) {
+           drbd_new_dev_size(mdev, nbc, nbc->disk_conf->disk_size, 0) < nbc->md.la_size_sect) {
                dev_warn(DEV, "refusing to truncate a consistent device\n");
                retcode = ERR_DISK_TO_SMALL;
                goto force_diskless_dec;
@@ -1419,11 +1438,13 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
 
        /* Reset the "barriers don't work" bits here, then force meta data to
         * be written, to ensure we determine if barriers are supported. */
-       if (nbc->dc.no_md_flush)
+       if (new_disk_conf->no_md_flush)
                set_bit(MD_NO_FUA, &mdev->flags);
        else
                clear_bit(MD_NO_FUA, &mdev->flags);
 
+       /* FIXME Missing stuff: rs_plan_s, clip al range */
+
        /* Point of no return reached.
         * Devices and memory are no longer released by error cleanup below.
         * now mdev takes over responsibility, and the state engine should
@@ -1433,6 +1454,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
        mdev->resync = resync_lru;
        nbc = NULL;
        resync_lru = NULL;
+       new_disk_conf = NULL;
 
        mdev->write_ordering = WO_bdev_flush;
        drbd_bump_write_ordering(mdev, WO_bdev_flush);
@@ -1530,9 +1552,11 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
        if (drbd_md_test_flag(mdev->ldev, MDF_PEER_OUT_DATED))
                ns.pdsk = D_OUTDATED;
 
-       if ( ns.disk == D_CONSISTENT &&
-           (ns.pdsk == D_OUTDATED || mdev->ldev->dc.fencing == FP_DONT_CARE))
+       rcu_read_lock();
+       if (ns.disk == D_CONSISTENT &&
+           (ns.pdsk == D_OUTDATED || rcu_dereference(mdev->ldev->disk_conf)->fencing == FP_DONT_CARE))
                ns.disk = D_UP_TO_DATE;
+       rcu_read_unlock();
 
        /* All tests on MDF_PRIMARY_IND, MDF_CONNECTED_IND,
           MDF_CONSISTENT and MDF_WAS_UP_TO_DATE must happen before
@@ -1589,6 +1613,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
                                   FMODE_READ | FMODE_WRITE | FMODE_EXCL);
                kfree(nbc);
        }
+       kfree(new_disk_conf);
        lc_destroy(resync_lru);
 
  finish:
@@ -1691,7 +1716,7 @@ _check_net_options(struct drbd_tconn *tconn, struct net_conf *old_conf, struct n
 
        idr_for_each_entry(&tconn->volumes, mdev, i) {
                if (get_ldev(mdev)) {
-                       enum drbd_fencing_p fp = mdev->ldev->dc.fencing;
+                       enum drbd_fencing_p fp = rcu_dereference(mdev->ldev->disk_conf)->fencing;
                        put_ldev(mdev);
                        if (new_conf->wire_protocol == DRBD_PROT_A && fp == FP_STONITH)
                                return ERR_STONITH_AND_PROT_A;
@@ -2159,11 +2184,13 @@ void resync_after_online_grow(struct drbd_conf *mdev)
 
 int drbd_adm_resize(struct sk_buff *skb, struct genl_info *info)
 {
+       struct disk_conf *old_disk_conf, *new_disk_conf = NULL;
        struct resize_parms rs;
        struct drbd_conf *mdev;
        enum drbd_ret_code retcode;
        enum determine_dev_size dd;
        enum dds_flags ddsf;
+       sector_t u_size;
        int err;
 
        retcode = drbd_adm_prepare(skb, info, DRBD_ADM_NEED_MINOR);
@@ -2204,10 +2231,31 @@ int drbd_adm_resize(struct sk_buff *skb, struct genl_info *info)
                goto fail;
        }
 
+       rcu_read_lock();
+       u_size = rcu_dereference(mdev->ldev->disk_conf)->disk_size;
+       rcu_read_unlock();
+       if (u_size != (sector_t)rs.resize_size) {
+               new_disk_conf = kmalloc(sizeof(struct disk_conf), GFP_KERNEL);
+               if (!new_disk_conf) {
+                       retcode = ERR_NOMEM;
+                       goto fail;
+               }
+       }
+
        if (mdev->ldev->known_size != drbd_get_capacity(mdev->ldev->backing_bdev))
                mdev->ldev->known_size = drbd_get_capacity(mdev->ldev->backing_bdev);
 
-       mdev->ldev->dc.disk_size = (sector_t)rs.resize_size;
+       if (new_disk_conf) {
+               mutex_lock(&mdev->tconn->conf_update);
+               old_disk_conf = mdev->ldev->disk_conf;
+               *new_disk_conf = *old_disk_conf;
+               new_disk_conf->disk_size = (sector_t)rs.resize_size;
+               rcu_assign_pointer(mdev->ldev->disk_conf, new_disk_conf);
+               mutex_unlock(&mdev->tconn->conf_update);
+               synchronize_rcu();
+               kfree(old_disk_conf);
+       }
+
        ddsf = (rs.resize_force ? DDSF_FORCED : 0) | (rs.no_resync ? DDSF_NO_RESYNC : 0);
        dd = drbd_determine_dev_size(mdev, ddsf);
        drbd_md_sync(mdev);
@@ -2501,11 +2549,11 @@ int nla_put_status_info(struct sk_buff *skb, struct drbd_conf *mdev,
        if (res_opts_to_skb(skb, &mdev->tconn->res_opts, exclude_sensitive))
                goto nla_put_failure;
 
+       rcu_read_lock();
        if (got_ldev)
-               if (disk_conf_to_skb(skb, &mdev->ldev->dc, exclude_sensitive))
+               if (disk_conf_to_skb(skb, rcu_dereference(mdev->ldev->disk_conf), exclude_sensitive))
                        goto nla_put_failure;
 
-       rcu_read_lock();
        nc = rcu_dereference(mdev->tconn->net_conf);
        if (nc)
                err = net_conf_to_skb(skb, nc, exclude_sensitive);
index bba0050f836ba8aac4ace7c42ccded48806c0296..add41764ec543ee67ac0306e5dccab5b34df2654 100644 (file)
@@ -1166,6 +1166,7 @@ static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *mdev,
  */
 void drbd_bump_write_ordering(struct drbd_conf *mdev, enum write_ordering_e wo) __must_hold(local)
 {
+       struct disk_conf *dc;
        enum write_ordering_e pwo;
        static char *write_ordering_str[] = {
                [WO_none] = "none",
@@ -1175,10 +1176,14 @@ void drbd_bump_write_ordering(struct drbd_conf *mdev, enum write_ordering_e wo)
 
        pwo = mdev->write_ordering;
        wo = min(pwo, wo);
-       if (wo == WO_bdev_flush && mdev->ldev->dc.no_disk_flush)
+       rcu_read_lock();
+       dc = rcu_dereference(mdev->ldev->disk_conf);
+
+       if (wo == WO_bdev_flush && dc->no_disk_flush)
                wo = WO_drain_io;
-       if (wo == WO_drain_io && mdev->ldev->dc.no_disk_drain)
+       if (wo == WO_drain_io && dc->no_disk_drain)
                wo = WO_none;
+       rcu_read_unlock();
        mdev->write_ordering = wo;
        if (pwo != mdev->write_ordering || wo == WO_bdev_flush)
                dev_info(DEV, "Method to ensure write ordering: %s\n", write_ordering_str[mdev->write_ordering]);
@@ -2190,9 +2195,14 @@ int drbd_rs_should_slow_down(struct drbd_conf *mdev, sector_t sector)
        struct lc_element *tmp;
        int curr_events;
        int throttle = 0;
+       unsigned int c_min_rate;
+
+       rcu_read_lock();
+       c_min_rate = rcu_dereference(mdev->ldev->disk_conf)->c_min_rate;
+       rcu_read_unlock();
 
        /* feature disabled? */
-       if (mdev->ldev->dc.c_min_rate == 0)
+       if (c_min_rate == 0)
                return 0;
 
        spin_lock_irq(&mdev->al_lock);
@@ -2232,7 +2242,7 @@ int drbd_rs_should_slow_down(struct drbd_conf *mdev, sector_t sector)
                db = mdev->rs_mark_left[i] - rs_left;
                dbdt = Bit2KB(db/dt);
 
-               if (dbdt > mdev->ldev->dc.c_min_rate)
+               if (dbdt > c_min_rate)
                        throttle = 1;
        }
        return throttle;
@@ -3147,6 +3157,7 @@ static int receive_SyncParam(struct drbd_tconn *tconn, struct packet_info *pi)
        struct crypto_hash *verify_tfm = NULL;
        struct crypto_hash *csums_tfm = NULL;
        struct net_conf *old_net_conf, *new_net_conf = NULL;
+       struct disk_conf *old_disk_conf, *new_disk_conf = NULL;
        const int apv = tconn->agreed_pro_version;
        int *rs_plan_s = NULL;
        int fifo_size = 0;
@@ -3189,24 +3200,34 @@ static int receive_SyncParam(struct drbd_tconn *tconn, struct packet_info *pi)
        if (err)
                return err;
 
-       if (get_ldev(mdev)) {
-               mdev->ldev->dc.resync_rate = be32_to_cpu(p->rate);
-               put_ldev(mdev);
+       new_disk_conf = kzalloc(sizeof(struct disk_conf), GFP_KERNEL);
+       if (!new_disk_conf) {
+               dev_err(DEV, "Allocation of new disk_conf failed\n");
+               return -ENOMEM;
        }
 
+       mutex_lock(&mdev->tconn->conf_update);
+       old_net_conf = mdev->tconn->net_conf;
+       old_disk_conf = mdev->ldev->disk_conf;
+       *new_disk_conf = *old_disk_conf;
+
+       new_disk_conf->resync_rate = be32_to_cpu(p->rate);
+
        if (apv >= 88) {
                if (apv == 88) {
                        if (data_size > SHARED_SECRET_MAX) {
                                dev_err(DEV, "verify-alg too long, "
                                    "peer wants %u, accepting only %u byte\n",
                                                data_size, SHARED_SECRET_MAX);
+                               mutex_unlock(&mdev->tconn->conf_update);
                                return -EIO;
                        }
 
                        err = drbd_recv_all(mdev->tconn, p->verify_alg, data_size);
-                       if (err)
+                       if (err) {
+                               mutex_unlock(&mdev->tconn->conf_update);
                                return err;
-
+                       }
                        /* we expect NUL terminated string */
                        /* but just in case someone tries to be evil */
                        D_ASSERT(p->verify_alg[data_size-1] == 0);
@@ -3221,9 +3242,6 @@ static int receive_SyncParam(struct drbd_tconn *tconn, struct packet_info *pi)
                        p->csums_alg[SHARED_SECRET_MAX-1] = 0;
                }
 
-               mutex_lock(&mdev->tconn->conf_update);
-               old_net_conf = mdev->tconn->net_conf;
-
                if (strcmp(old_net_conf->verify_alg, p->verify_alg)) {
                        if (mdev->state.conn == C_WF_REPORT_PARAMS) {
                                dev_err(DEV, "Different verify-alg settings. me=\"%s\" peer=\"%s\"\n",
@@ -3252,14 +3270,13 @@ static int receive_SyncParam(struct drbd_tconn *tconn, struct packet_info *pi)
                        }
                }
 
-               if (apv > 94 && get_ldev(mdev)) {
-                       mdev->ldev->dc.resync_rate = be32_to_cpu(p->rate);
-                       mdev->ldev->dc.c_plan_ahead = be32_to_cpu(p->c_plan_ahead);
-                       mdev->ldev->dc.c_delay_target = be32_to_cpu(p->c_delay_target);
-                       mdev->ldev->dc.c_fill_target = be32_to_cpu(p->c_fill_target);
-                       mdev->ldev->dc.c_max_rate = be32_to_cpu(p->c_max_rate);
+               if (apv > 94) {
+                       new_disk_conf->c_plan_ahead = be32_to_cpu(p->c_plan_ahead);
+                       new_disk_conf->c_delay_target = be32_to_cpu(p->c_delay_target);
+                       new_disk_conf->c_fill_target = be32_to_cpu(p->c_fill_target);
+                       new_disk_conf->c_max_rate = be32_to_cpu(p->c_max_rate);
 
-                       fifo_size = (mdev->ldev->dc.c_plan_ahead * 10 * SLEEP_TIME) / HZ;
+                       fifo_size = (new_disk_conf->c_plan_ahead * 10 * SLEEP_TIME) / HZ;
                        if (fifo_size != mdev->rs_plan_s.size && fifo_size > 0) {
                                rs_plan_s   = kzalloc(sizeof(int) * fifo_size, GFP_KERNEL);
                                if (!rs_plan_s) {
@@ -3268,7 +3285,6 @@ static int receive_SyncParam(struct drbd_tconn *tconn, struct packet_info *pi)
                                        goto disconnect;
                                }
                        }
-                       put_ldev(mdev);
                }
 
                if (verify_tfm || csums_tfm) {
@@ -3296,21 +3312,24 @@ static int receive_SyncParam(struct drbd_tconn *tconn, struct packet_info *pi)
                        }
                        rcu_assign_pointer(tconn->net_conf, new_net_conf);
                }
-               mutex_unlock(&mdev->tconn->conf_update);
-               if (new_net_conf) {
-                       synchronize_rcu();
-                       kfree(old_net_conf);
-               }
+       }
 
-               spin_lock(&mdev->peer_seq_lock);
-               if (fifo_size != mdev->rs_plan_s.size) {
-                       kfree(mdev->rs_plan_s.values);
-                       mdev->rs_plan_s.values = rs_plan_s;
-                       mdev->rs_plan_s.size   = fifo_size;
-                       mdev->rs_planed = 0;
-               }
-               spin_unlock(&mdev->peer_seq_lock);
+       rcu_assign_pointer(mdev->ldev->disk_conf, new_disk_conf);
+       spin_lock(&mdev->peer_seq_lock);
+       if (rs_plan_s) {
+               kfree(mdev->rs_plan_s.values);
+               mdev->rs_plan_s.values = rs_plan_s;
+               mdev->rs_plan_s.size   = fifo_size;
+               mdev->rs_planed = 0;
        }
+       spin_unlock(&mdev->peer_seq_lock);
+
+       mutex_unlock(&mdev->tconn->conf_update);
+       synchronize_rcu();
+       if (new_net_conf)
+               kfree(old_net_conf);
+       kfree(old_disk_conf);
+
        return 0;
 
 disconnect:
@@ -3358,37 +3377,56 @@ static int receive_sizes(struct drbd_tconn *tconn, struct packet_info *pi)
        mdev->p_size = p_size;
 
        if (get_ldev(mdev)) {
+               rcu_read_lock();
+               my_usize = rcu_dereference(mdev->ldev->disk_conf)->disk_size;
+               rcu_read_unlock();
+
                warn_if_differ_considerably(mdev, "lower level device sizes",
                           p_size, drbd_get_max_capacity(mdev->ldev));
                warn_if_differ_considerably(mdev, "user requested size",
-                                           p_usize, mdev->ldev->dc.disk_size);
+                                           p_usize, my_usize);
 
                /* if this is the first connect, or an otherwise expected
                 * param exchange, choose the minimum */
                if (mdev->state.conn == C_WF_REPORT_PARAMS)
-                       p_usize = min_not_zero((sector_t)mdev->ldev->dc.disk_size,
-                                            p_usize);
-
-               my_usize = mdev->ldev->dc.disk_size;
-
-               if (mdev->ldev->dc.disk_size != p_usize) {
-                       mdev->ldev->dc.disk_size = p_usize;
-                       dev_info(DEV, "Peer sets u_size to %lu sectors\n",
-                            (unsigned long)mdev->ldev->dc.disk_size);
-               }
+                       p_usize = min_not_zero(my_usize, p_usize);
 
                /* Never shrink a device with usable data during connect.
                   But allow online shrinking if we are connected. */
                if (drbd_new_dev_size(mdev, mdev->ldev, p_usize, 0) <
-                  drbd_get_capacity(mdev->this_bdev) &&
-                  mdev->state.disk >= D_OUTDATED &&
-                  mdev->state.conn < C_CONNECTED) {
+                   drbd_get_capacity(mdev->this_bdev) &&
+                   mdev->state.disk >= D_OUTDATED &&
+                   mdev->state.conn < C_CONNECTED) {
                        dev_err(DEV, "The peer's disk size is too small!\n");
                        conn_request_state(mdev->tconn, NS(conn, C_DISCONNECTING), CS_HARD);
-                       mdev->ldev->dc.disk_size = my_usize;
                        put_ldev(mdev);
                        return -EIO;
                }
+
+               if (my_usize != p_usize) {
+                       struct disk_conf *old_disk_conf, *new_disk_conf = NULL;
+
+                       new_disk_conf = kzalloc(sizeof(struct disk_conf), GFP_KERNEL);
+                       if (!new_disk_conf) {
+                               dev_err(DEV, "Allocation of new disk_conf failed\n");
+                               put_ldev(mdev);
+                               return -ENOMEM;
+                       }
+
+                       mutex_lock(&mdev->tconn->conf_update);
+                       old_disk_conf = mdev->ldev->disk_conf;
+                       *new_disk_conf = *old_disk_conf;
+                       new_disk_conf->disk_size = p_usize;
+
+                       rcu_assign_pointer(mdev->ldev->disk_conf, new_disk_conf);
+                       mutex_unlock(&mdev->tconn->conf_update);
+                       synchronize_rcu();
+                       kfree(old_disk_conf);
+
+                       dev_info(DEV, "Peer sets u_size to %lu sectors\n",
+                                (unsigned long)my_usize);
+               }
+
                put_ldev(mdev);
        }
 
@@ -4268,7 +4306,9 @@ static int drbd_disconnected(int vnr, void *p, void *data)
 
        fp = FP_DONT_CARE;
        if (get_ldev(mdev)) {
-               fp = mdev->ldev->dc.fencing;
+               rcu_read_lock();
+               fp = rcu_dereference(mdev->ldev->disk_conf)->fencing;
+               rcu_read_unlock();
                put_ldev(mdev);
        }
 
index 332781cfb556e04a1aa189ef32ad6fa2d2aacf7b..cd55f46d5c5577f11113dca603b0d902d0c25e7e 100644 (file)
@@ -483,13 +483,13 @@ is_valid_state(struct drbd_conf *mdev, union drbd_state ns)
        enum drbd_state_rv rv = SS_SUCCESS;
        struct net_conf *nc;
 
+       rcu_read_lock();
        fp = FP_DONT_CARE;
        if (get_ldev(mdev)) {
-               fp = mdev->ldev->dc.fencing;
+               fp = rcu_dereference(mdev->ldev->disk_conf)->fencing;
                put_ldev(mdev);
        }
 
-       rcu_read_lock();
        nc = rcu_dereference(mdev->tconn->net_conf);
        if (nc) {
                if (!nc->two_primaries && ns.role == R_PRIMARY) {
@@ -674,7 +674,9 @@ static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state
 
        fp = FP_DONT_CARE;
        if (get_ldev(mdev)) {
-               fp = mdev->ldev->dc.fencing;
+               rcu_read_lock();
+               fp = rcu_dereference(mdev->ldev->disk_conf)->fencing;
+               rcu_read_unlock();
                put_ldev(mdev);
        }
 
@@ -1132,7 +1134,9 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
 
        fp = FP_DONT_CARE;
        if (get_ldev(mdev)) {
-               fp = mdev->ldev->dc.fencing;
+               rcu_read_lock();
+               fp = rcu_dereference(mdev->ldev->disk_conf)->fencing;
+               rcu_read_unlock();
                put_ldev(mdev);
        }
 
@@ -1287,7 +1291,9 @@ static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
                /* corresponding get_ldev was in __drbd_set_state, to serialize
                 * our cleanup here with the transition to D_DISKLESS,
                 * so it is safe to dreference ldev here. */
-               eh = mdev->ldev->dc.on_io_error;
+               rcu_read_lock();
+               eh = rcu_dereference(mdev->ldev->disk_conf)->on_io_error;
+               rcu_read_unlock();
                was_io_error = test_and_clear_bit(WAS_IO_ERROR, &mdev->flags);
 
                /* current state still has to be D_FAILED,
index 5b645e1070807a2a6d4ecd7df127a197931abb1d..4f45f75173ac603e71e938c47956af6d14d7c4b0 100644 (file)
@@ -436,6 +436,7 @@ static void fifo_add_val(struct fifo_buffer *fb, int value)
 
 static int drbd_rs_controller(struct drbd_conf *mdev)
 {
+       struct disk_conf *dc;
        unsigned int sect_in;  /* Number of sectors that came in since the last turn */
        unsigned int want;     /* The number of sectors we want in the proxy */
        int req_sect; /* Number of sectors to request in this turn */
@@ -449,14 +450,16 @@ static int drbd_rs_controller(struct drbd_conf *mdev)
        mdev->rs_in_flight -= sect_in;
 
        spin_lock(&mdev->peer_seq_lock); /* get an atomic view on mdev->rs_plan_s */
+       rcu_read_lock();
+       dc = rcu_dereference(mdev->ldev->disk_conf);
 
-       steps = mdev->rs_plan_s.size; /* (mdev->ldev->dc.c_plan_ahead * 10 * SLEEP_TIME) / HZ; */
+       steps = mdev->rs_plan_s.size; /* (dc->c_plan_ahead * 10 * SLEEP_TIME) / HZ; */
 
        if (mdev->rs_in_flight + sect_in == 0) { /* At start of resync */
-               want = ((mdev->ldev->dc.resync_rate * 2 * SLEEP_TIME) / HZ) * steps;
+               want = ((dc->resync_rate * 2 * SLEEP_TIME) / HZ) * steps;
        } else { /* normal path */
-               want = mdev->ldev->dc.c_fill_target ? mdev->ldev->dc.c_fill_target :
-                       sect_in * mdev->ldev->dc.c_delay_target * HZ / (SLEEP_TIME * 10);
+               want = dc->c_fill_target ? dc->c_fill_target :
+                       sect_in * dc->c_delay_target * HZ / (SLEEP_TIME * 10);
        }
 
        correction = want - mdev->rs_in_flight - mdev->rs_planed;
@@ -468,14 +471,13 @@ static int drbd_rs_controller(struct drbd_conf *mdev)
 
        /* What we do in this step */
        curr_corr = fifo_push(&mdev->rs_plan_s, 0);
-       spin_unlock(&mdev->peer_seq_lock);
        mdev->rs_planed -= curr_corr;
 
        req_sect = sect_in + curr_corr;
        if (req_sect < 0)
                req_sect = 0;
 
-       max_sect = (mdev->ldev->dc.c_max_rate * 2 * SLEEP_TIME) / HZ;
+       max_sect = (dc->c_max_rate * 2 * SLEEP_TIME) / HZ;
        if (req_sect > max_sect)
                req_sect = max_sect;
 
@@ -484,6 +486,8 @@ static int drbd_rs_controller(struct drbd_conf *mdev)
                 sect_in, mdev->rs_in_flight, want, correction,
                 steps, cps, mdev->rs_planed, curr_corr, req_sect);
        */
+       rcu_read_unlock();
+       spin_unlock(&mdev->peer_seq_lock);
 
        return req_sect;
 }
@@ -491,11 +495,13 @@ static int drbd_rs_controller(struct drbd_conf *mdev)
 static int drbd_rs_number_requests(struct drbd_conf *mdev)
 {
        int number;
-       if (mdev->rs_plan_s.size) { /* mdev->ldev->dc.c_plan_ahead */
+       if (mdev->rs_plan_s.size) { /* rcu_dereference(mdev->ldev->disk_conf)->c_plan_ahead */
                number = drbd_rs_controller(mdev) >> (BM_BLOCK_SHIFT - 9);
                mdev->c_sync_rate = number * HZ * (BM_BLOCK_SIZE / 1024) / SLEEP_TIME;
        } else {
-               mdev->c_sync_rate = mdev->ldev->dc.resync_rate;
+               rcu_read_lock();
+               mdev->c_sync_rate = rcu_dereference(mdev->ldev->disk_conf)->resync_rate;
+               rcu_read_unlock();
                number = SLEEP_TIME * mdev->c_sync_rate  / ((BM_BLOCK_SIZE / 1024) * HZ);
        }
 
@@ -1320,13 +1326,17 @@ int w_restart_disk_io(struct drbd_work *w, int cancel)
 static int _drbd_may_sync_now(struct drbd_conf *mdev)
 {
        struct drbd_conf *odev = mdev;
+       int ra;
 
        while (1) {
                if (!odev->ldev)
                        return 1;
-               if (odev->ldev->dc.resync_after == -1)
+               rcu_read_lock();
+               ra = rcu_dereference(odev->ldev->disk_conf)->resync_after;
+               rcu_read_unlock();
+               if (ra == -1)
                        return 1;
-               odev = minor_to_mdev(odev->ldev->dc.resync_after);
+               odev = minor_to_mdev(ra);
                if (!expect(odev))
                        return 1;
                if ((odev->state.conn >= C_SYNC_SOURCE &&
@@ -1405,6 +1415,7 @@ void suspend_other_sg(struct drbd_conf *mdev)
 enum drbd_ret_code drbd_sync_after_valid(struct drbd_conf *mdev, int o_minor)
 {
        struct drbd_conf *odev;
+       int ra;
 
        if (o_minor == -1)
                return NO_ERROR;
@@ -1417,12 +1428,15 @@ enum drbd_ret_code drbd_sync_after_valid(struct drbd_conf *mdev, int o_minor)
                if (odev == mdev)
                        return ERR_SYNC_AFTER_CYCLE;
 
+               rcu_read_lock();
+               ra = rcu_dereference(odev->ldev->disk_conf)->resync_after;
+               rcu_read_unlock();
                /* dependency chain ends here, no cycles. */
-               if (odev->ldev->dc.resync_after == -1)
+               if (ra == -1)
                        return NO_ERROR;
 
                /* follow the dependency chain */
-               odev = minor_to_mdev(odev->ldev->dc.resync_after);
+               odev = minor_to_mdev(ra);
        }
 }