4 files changed, 42 insertions, 2 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index ad96495dedc5..213535f45da2 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -881,6 +881,9 @@ struct btrfs_fs_info {
         u64 metadata_alloc_profile;
         u64 system_alloc_profile;
 
+        unsigned data_chunk_allocations;
+        unsigned metadata_ratio;
+
         void *bdev_holder;
 };
 
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index a6b83744b05d..44c94d808e2b 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1604,6 +1604,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         fs_info->btree_inode = new_inode(sb);
         fs_info->btree_inode->i_ino = 1;
         fs_info->btree_inode->i_nlink = 1;
+        fs_info->metadata_ratio = 8;
 
         fs_info->thread_pool_size = min_t(unsigned long,
                                           num_online_cpus() + 2, 8);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 178df4c67de4..2895a8373232 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1918,15 +1918,29 @@ void btrfs_delalloc_free_space(struct btrfs_root *root, struct inode *inode,
         spin_unlock(&info->lock);
 }
 
+static void force_metadata_allocation(struct btrfs_fs_info *info)
+{
+        struct list_head *head = &info->space_info;
+        struct btrfs_space_info *found;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(found, head, list) {
+                if (found->flags & BTRFS_BLOCK_GROUP_METADATA)
+                        found->force_alloc = 1;
+        }
+        rcu_read_unlock();
+}
+
 static int do_chunk_alloc(struct btrfs_trans_handle *trans,
                           struct btrfs_root *extent_root, u64 alloc_bytes,
                           u64 flags, int force)
 {
         struct btrfs_space_info *space_info;
+        struct btrfs_fs_info *fs_info = extent_root->fs_info;
         u64 thresh;
         int ret = 0;
 
-        mutex_lock(&extent_root->fs_info->chunk_mutex);
+        mutex_lock(&fs_info->chunk_mutex);
 
         flags = btrfs_reduce_alloc_profile(extent_root, flags);
 
@@ -1958,6 +1972,18 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
         }
         spin_unlock(&space_info->lock);
 
+        /*
+         * if we're doing a data chunk, go ahead and make sure that
+         * we keep a reasonable number of metadata chunks allocated in the
+         * FS as well.
+         */
+        if (flags & BTRFS_BLOCK_GROUP_DATA) {
+                fs_info->data_chunk_allocations++;
+                if (!(fs_info->data_chunk_allocations %
+                      fs_info->metadata_ratio))
+                        force_metadata_allocation(fs_info);
+        }
+
         ret = btrfs_alloc_chunk(trans, extent_root, flags);
         if (ret)
                 space_info->full = 1;
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 9744af9d71e9..30c9a8ca2a54 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -68,7 +68,7 @@ enum {
         Opt_degraded, Opt_subvol, Opt_device, Opt_nodatasum, Opt_nodatacow,
         Opt_max_extent, Opt_max_inline, Opt_alloc_start, Opt_nobarrier,
         Opt_ssd, Opt_thread_pool, Opt_noacl,  Opt_compress, Opt_notreelog,
-        Opt_flushoncommit, Opt_err,
+        Opt_ratio, Opt_flushoncommit, Opt_err,
 };
 
 static match_table_t tokens = {
@@ -87,6 +87,7 @@ static match_table_t tokens = {
         {Opt_noacl, "noacl"},
         {Opt_notreelog, "notreelog"},
         {Opt_flushoncommit, "flushoncommit"},
+        {Opt_ratio, "metadata_ratio=%d"},
         {Opt_err, NULL},
 };
 
@@ -234,6 +235,15 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
                         break;
+                case Opt_ratio:
+                        intarg = 0;
+                        match_int(&args[0], &intarg);
+                        if (intarg) {
+                                info->metadata_ratio = intarg;
+                                printk(KERN_INFO "btrfs: metadata ratio %d\n",
+                                       info->metadata_ratio);
+                        }
+                        break;
                 default:
                         break;
                 }