3 files changed, 53 insertions, 3 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 82491ba8fa40..5e1d4e30e9d8 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -784,7 +784,14 @@ struct btrfs_fs_info {
         struct list_head dirty_cowonly_roots;
 
         struct btrfs_fs_devices *fs_devices;
+
+        /*
+         * the space_info list is almost entirely read only.  It only changes
+         * when we add a new raid type to the FS, and that happens
+         * very rarely.  RCU is used to protect it.
+         */
         struct list_head space_info;
+
         spinlock_t delalloc_lock;
         spinlock_t new_trans_lock;
         u64 delalloc_bytes;
@@ -1797,6 +1804,8 @@ int btrfs_cleanup_reloc_trees(struct btrfs_root *root);
 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len);
 u64 btrfs_reduce_alloc_profile(struct btrfs_root *root, u64 flags);
 void btrfs_set_inode_space_info(struct btrfs_root *root, struct inode *ionde);
+void btrfs_clear_space_info_full(struct btrfs_fs_info *info);
+
 int btrfs_check_metadata_free_space(struct btrfs_root *root);
 int btrfs_check_data_free_space(struct btrfs_root *root, struct inode *inode,
                                 u64 bytes);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 9abf81f71c46..fefe83ad2059 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -20,6 +20,7 @@
 #include <linux/writeback.h>
 #include <linux/blkdev.h>
 #include <linux/sort.h>
+#include <linux/rcupdate.h>
 #include "compat.h"
 #include "hash.h"
 #include "crc32c.h"
@@ -330,13 +331,33 @@ static struct btrfs_space_info *__find_space_info(struct btrfs_fs_info *info,
 {
         struct list_head *head = &info->space_info;
         struct btrfs_space_info *found;
-        list_for_each_entry(found, head, list) {
-                if (found->flags == flags)
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(found, head, list) {
+                if (found->flags == flags) {
+                        rcu_read_unlock();
                         return found;
+                }
         }
+        rcu_read_unlock();
         return NULL;
 }
 
+/*
+ * after adding space to the filesystem, we need to clear the full flags
+ * on all the space infos.
+ */
+void btrfs_clear_space_info_full(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)
+                found->full = 0;
+        rcu_read_unlock();
+}
+
 static u64 div_factor(u64 num, int factor)
 {
         if (factor == 10)
@@ -1903,7 +1924,6 @@ static int update_space_info(struct btrfs_fs_info *info, u64 flags,
         if (!found)
                 return -ENOMEM;
 
-        list_add(&found->list, &info->space_info);
         INIT_LIST_HEAD(&found->block_groups);
         init_rwsem(&found->groups_sem);
         spin_lock_init(&found->lock);
@@ -1917,6 +1937,7 @@ static int update_space_info(struct btrfs_fs_info *info, u64 flags,
         found->full = 0;
         found->force_alloc = 0;
         *space_info = found;
+        list_add_rcu(&found->list, &info->space_info);
         return 0;
 }
 
@@ -6320,6 +6341,7 @@ out:
 int btrfs_free_block_groups(struct btrfs_fs_info *info)
 {
         struct btrfs_block_group_cache *block_group;
+        struct btrfs_space_info *space_info;
         struct rb_node *n;
 
         spin_lock(&info->block_group_cache_lock);
@@ -6341,6 +6363,23 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info)
                 spin_lock(&info->block_group_cache_lock);
         }
         spin_unlock(&info->block_group_cache_lock);
+
+        /* now that all the block groups are freed, go through and
+         * free all the space_info structs.  This is only called during
+         * the final stages of unmount, and so we know nobody is
+         * using them.  We call synchronize_rcu() once before we start,
+         * just to be on the safe side.
+         */
+        synchronize_rcu();
+
+        while(!list_empty(&info->space_info)) {
+                space_info = list_entry(info->space_info.next,
+                                        struct btrfs_space_info,
+                                        list);
+
+                list_del(&space_info->list);
+                kfree(space_info);
+        }
         return 0;
 }
 
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 1316139bf9e8..7aa3810d7f69 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1459,6 +1459,8 @@ static int __btrfs_grow_device(struct btrfs_trans_handle *trans,
         device->fs_devices->total_rw_bytes += diff;
 
         device->total_bytes = new_size;
+        btrfs_clear_space_info_full(device->dev_root->fs_info);
+
         return btrfs_update_device(trans, device);
 }