drbd: Allow online change of al-stripes and al-stripe-size

Allow to change the AL layout with an resize operation. For that
the reisze command gets two new fields: al_stripes and al_stripe_size.

In order to make the operation crash save:
1) Lock out all IO and MD-IO
2) Write the super block with MDF_PRIMARY_IND clear
3) write the bitmap to the new location (all zeros, since
   we allow only while connected)
4) Initialize the new AL-area
5) Write the super block with the restored MDF_PRIMARY_IND.
6) Unfreeze all IO

Since the AL-layout has no influence on the protocol, this operation
needs to be beforemed on both sides of a resource (if intended).

Signed-off-by: Andreas Gruenbacher <agruen@linbit.com>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 111 insertions, 26 deletions

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 45d127522e0a..8cc1e640f485 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -827,12 +827,17 @@ void drbd_resume_io(struct drbd_conf *mdev)
  * Returns 0 on success, negative return values indicate errors.
  * You should call drbd_md_sync() after calling this function.
  */
-enum determine_dev_size drbd_determine_dev_size(struct drbd_conf *mdev, enum dds_flags flags) __must_hold(local)
+enum determine_dev_size
+drbd_determine_dev_size(struct drbd_conf *mdev, enum dds_flags flags, struct resize_parms *rs) __must_hold(local)
 {
         sector_t prev_first_sect, prev_size; /* previous meta location */
         sector_t la_size_sect, u_size;
+        struct drbd_md *md = &mdev->ldev->md;
+        u32 prev_al_stripe_size_4k;
+        u32 prev_al_stripes;
         sector_t size;
         char ppb[10];
+        void *buffer;
 
         int md_moved, la_size_changed;
         enum determine_dev_size rv = DS_UNCHANGED;
@@ -847,6 +852,11 @@ enum determine_dev_size drbd_determine_dev_size(struct drbd_conf *mdev, enum dds
          * still lock the act_log to not trigger ASSERTs there.
          */
         drbd_suspend_io(mdev);
+        buffer = drbd_md_get_buffer(mdev); /* Lock meta-data IO */
+        if (!buffer) {
+                drbd_resume_io(mdev);
+                return DS_ERROR;
+        }
 
         /* no wait necessary anymore, actually we could assert that */
         wait_event(mdev->al_wait, lc_try_lock(mdev->act_log));
@@ -855,7 +865,17 @@ enum determine_dev_size drbd_determine_dev_size(struct drbd_conf *mdev, enum dds
         prev_size = mdev->ldev->md.md_size_sect;
         la_size_sect = mdev->ldev->md.la_size_sect;
 
-        /* TODO: should only be some assert here, not (re)init... */
+        if (rs) {
+                /* rs is non NULL if we should change the AL layout only */
+
+                prev_al_stripes = md->al_stripes;
+                prev_al_stripe_size_4k = md->al_stripe_size_4k;
+
+                md->al_stripes = rs->al_stripes;
+                md->al_stripe_size_4k = rs->al_stripe_size / 4;
+                md->al_size_4k = (u64)rs->al_stripes * rs->al_stripe_size / 4;
+        }
+
         drbd_md_set_sector_offsets(mdev, mdev->ldev);
 
         rcu_read_lock();
@@ -863,6 +883,21 @@ enum determine_dev_size drbd_determine_dev_size(struct drbd_conf *mdev, enum dds
         rcu_read_unlock();
         size = drbd_new_dev_size(mdev, mdev->ldev, u_size, flags & DDSF_FORCED);
 
+        if (size < la_size_sect) {
+                if (rs && u_size == 0) {
+                        /* Remove "rs &&" later. This check should always be active, but
+                           right now the receiver expects the permissive behavior */
+                        dev_warn(DEV, "Implicit shrink not allowed. "
+                                 "Use --size=%llus for explicit shrink.\n",
+                                 (unsigned long long)size);
+                        rv = DS_ERROR_SHRINK;
+                }
+                if (u_size > size)
+                        rv = DS_ERROR_SPACE_MD;
+                if (rv != DS_UNCHANGED)
+                        goto err_out;
+        }
+
         if (drbd_get_capacity(mdev->this_bdev) != size ||
             drbd_bm_capacity(mdev) != size) {
                 int err;
@@ -886,38 +921,57 @@ enum determine_dev_size drbd_determine_dev_size(struct drbd_conf *mdev, enum dds
                 dev_info(DEV, "size = %s (%llu KB)\n", ppsize(ppb, size>>1),
                      (unsigned long long)size>>1);
         }
-        if (rv == DS_ERROR)
-                goto out;
+        if (rv <= DS_ERROR)
+                goto err_out;
 
         la_size_changed = (la_size_sect != mdev->ldev->md.la_size_sect);
 
         md_moved = prev_first_sect != drbd_md_first_sector(mdev->ldev)
                 || prev_size       != mdev->ldev->md.md_size_sect;
 
-        if (la_size_changed || md_moved) {
-                int err;
+        if (la_size_changed || md_moved || rs) {
+                u32 prev_flags;
 
                 drbd_al_shrink(mdev); /* All extents inactive. */
+
+                prev_flags = md->flags;
+                md->flags &= ~MDF_PRIMARY_IND;
+                drbd_md_write(mdev, buffer);
+
                 dev_info(DEV, "Writing the whole bitmap, %s\n",
                          la_size_changed && md_moved ? "size changed and md moved" :
                          la_size_changed ? "size changed" : "md moved");
                 /* next line implicitly does drbd_suspend_io()+drbd_resume_io() */
-                err = drbd_bitmap_io(mdev, md_moved ? &drbd_bm_write_all : &drbd_bm_write,
-                                     "size changed", BM_LOCKED_MASK);
-                if (err) {
-                        rv = DS_ERROR;
-                        goto out;
-                }
-                drbd_md_mark_dirty(mdev);
+                drbd_bitmap_io(mdev, md_moved ? &drbd_bm_write_all : &drbd_bm_write,
+                               "size changed", BM_LOCKED_MASK);
+                drbd_initialize_al(mdev, buffer);
+
+                md->flags = prev_flags;
+                drbd_md_write(mdev, buffer);
+
+                if (rs)
+                        dev_info(DEV, "Changed AL layout to al-stripes = %d, al-stripe-size-kB = %d\n",
+                                 md->al_stripes, md->al_stripe_size_4k * 4);
         }
 
         if (size > la_size_sect)
                 rv = DS_GREW;
         if (size < la_size_sect)
                 rv = DS_SHRUNK;
-out:
+
+        if (0) {
+        err_out:
+                if (rs) {
+                        md->al_stripes = prev_al_stripes;
+                        md->al_stripe_size_4k = prev_al_stripe_size_4k;
+                        md->al_size_4k = (u64)prev_al_stripes * prev_al_stripe_size_4k;
+
+                        drbd_md_set_sector_offsets(mdev, mdev->ldev);
+                }
+        }
         lc_unlock(mdev->act_log);
         wake_up(&mdev->al_wait);
+        drbd_md_put_buffer(mdev);
         drbd_resume_io(mdev);
 
         return rv;
@@ -1618,8 +1672,8 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
             !drbd_md_test_flag(mdev->ldev, MDF_CONNECTED_IND))
                 set_bit(USE_DEGR_WFC_T, &mdev->flags);
 
-        dd = drbd_determine_dev_size(mdev, 0);
-        if (dd == DS_ERROR) {
+        dd = drbd_determine_dev_size(mdev, 0, NULL);
+        if (dd <= DS_ERROR) {
                 retcode = ERR_NOMEM_BITMAP;
                 goto force_diskless_dec;
         } else if (dd == DS_GREW)
@@ -2316,6 +2370,7 @@ int drbd_adm_resize(struct sk_buff *skb, struct genl_info *info)
         struct drbd_conf *mdev;
         enum drbd_ret_code retcode;
         enum determine_dev_size dd;
+        bool change_al_layout = false;
         enum dds_flags ddsf;
         sector_t u_size;
         int err;
@@ -2326,31 +2381,33 @@ int drbd_adm_resize(struct sk_buff *skb, struct genl_info *info)
         if (retcode != NO_ERROR)
                 goto fail;
 
+        mdev = adm_ctx.mdev;
+        if (!get_ldev(mdev)) {
+                retcode = ERR_NO_DISK;
+                goto fail;
+        }
+
         memset(&rs, 0, sizeof(struct resize_parms));
+        rs.al_stripes = mdev->ldev->md.al_stripes;
+        rs.al_stripe_size = mdev->ldev->md.al_stripe_size_4k * 4;
         if (info->attrs[DRBD_NLA_RESIZE_PARMS]) {
                 err = resize_parms_from_attrs(&rs, info);
                 if (err) {
                         retcode = ERR_MANDATORY_TAG;
                         drbd_msg_put_info(from_attrs_err_to_txt(err));
-                        goto fail;
+                        goto fail_ldev;
                 }
         }
 
-        mdev = adm_ctx.mdev;
         if (mdev->state.conn > C_CONNECTED) {
                 retcode = ERR_RESIZE_RESYNC;
-                goto fail;
+                goto fail_ldev;
         }
 
         if (mdev->state.role == R_SECONDARY &&
             mdev->state.peer == R_SECONDARY) {
                 retcode = ERR_NO_PRIMARY;
-                goto fail;
-        }
-
-        if (!get_ldev(mdev)) {
-                retcode = ERR_NO_DISK;
-                goto fail;
+                goto fail_ldev;
         }
 
         if (rs.no_resync && mdev->tconn->agreed_pro_version < 93) {
@@ -2369,6 +2426,28 @@ int drbd_adm_resize(struct sk_buff *skb, struct genl_info *info)
                 }
         }
 
+        if (mdev->ldev->md.al_stripes != rs.al_stripes ||
+            mdev->ldev->md.al_stripe_size_4k != rs.al_stripe_size / 4) {
+                u32 al_size_k = rs.al_stripes * rs.al_stripe_size;
+
+                if (al_size_k > (16 * 1024 * 1024)) {
+                        retcode = ERR_MD_LAYOUT_TOO_BIG;
+                        goto fail_ldev;
+                }
+
+                if (al_size_k < MD_32kB_SECT/2) {
+                        retcode = ERR_MD_LAYOUT_TOO_SMALL;
+                        goto fail_ldev;
+                }
+
+                if (mdev->state.conn != C_CONNECTED) {
+                        retcode = ERR_MD_LAYOUT_CONNECTED;
+                        goto fail_ldev;
+                }
+
+                change_al_layout = true;
+        }
+
         if (mdev->ldev->known_size != drbd_get_capacity(mdev->ldev->backing_bdev))
                 mdev->ldev->known_size = drbd_get_capacity(mdev->ldev->backing_bdev);
 
@@ -2384,12 +2463,18 @@ int drbd_adm_resize(struct sk_buff *skb, struct genl_info *info)
         }
 
         ddsf = (rs.resize_force ? DDSF_FORCED : 0) | (rs.no_resync ? DDSF_NO_RESYNC : 0);
-        dd = drbd_determine_dev_size(mdev, ddsf);
+        dd = drbd_determine_dev_size(mdev, ddsf, change_al_layout ? &rs : NULL);
         drbd_md_sync(mdev);
         put_ldev(mdev);
         if (dd == DS_ERROR) {
                 retcode = ERR_NOMEM_BITMAP;
                 goto fail;
+        } else if (dd == DS_ERROR_SPACE_MD) {
+                retcode = ERR_MD_LAYOUT_NO_FIT;
+                goto fail;
+        } else if (dd == DS_ERROR_SHRINK) {
+                retcode = ERR_IMPLICIT_SHRINK;
+                goto fail;
         }
 
         if (mdev->state.conn == C_CONNECTED) {