6 files changed, 439 insertions, 124 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 0cbf3491bb7c..42b03c4ee494 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -691,6 +691,7 @@ struct btrfs_space_info {
         struct list_head block_groups;
         spinlock_t lock;
         struct rw_semaphore groups_sem;
+        atomic_t caching_threads;
 };
 
 /*
@@ -721,11 +722,17 @@ struct btrfs_free_cluster {
         struct list_head block_group_list;
 };
 
+enum btrfs_caching_type {
+        BTRFS_CACHE_NO          = 0,
+        BTRFS_CACHE_STARTED     = 1,
+        BTRFS_CACHE_FINISHED    = 2,
+};
+
 struct btrfs_block_group_cache {
         struct btrfs_key key;
         struct btrfs_block_group_item item;
+        struct btrfs_fs_info *fs_info;
         spinlock_t lock;
-        struct mutex cache_mutex;
         u64 pinned;
         u64 reserved;
         u64 flags;
@@ -733,15 +740,19 @@ struct btrfs_block_group_cache {
         int extents_thresh;
         int free_extents;
         int total_bitmaps;
-        int cached;
         int ro;
         int dirty;
 
+        /* cache tracking stuff */
+        wait_queue_head_t caching_q;
+        int cached;
+
         struct btrfs_space_info *space_info;
 
         /* free space cache stuff */
         spinlock_t tree_lock;
         struct rb_root free_space_offset;
+        u64 free_space;
 
         /* block group cache stuff */
         struct rb_node cache_node;
@@ -834,6 +845,7 @@ struct btrfs_fs_info {
         atomic_t async_submit_draining;
         atomic_t nr_async_bios;
         atomic_t async_delalloc_pages;
+        atomic_t async_caching_threads;
 
         /*
          * this is used by the balancing code to wait for all the pending
@@ -950,6 +962,9 @@ struct btrfs_root {
         /* the node lock is held while changing the node pointer */
         spinlock_t node_lock;
 
+        /* taken when updating the commit root */
+        struct rw_semaphore commit_root_sem;
+
         struct extent_buffer *commit_root;
         struct btrfs_root *log_root;
         struct btrfs_root *reloc_root;
@@ -1911,7 +1926,7 @@ int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
                            struct btrfs_root *root, unsigned long count);
 int btrfs_lookup_extent(struct btrfs_root *root, u64 start, u64 len);
 int btrfs_update_pinned_extents(struct btrfs_root *root,
-                                u64 bytenr, u64 num, int pin);
+                                u64 bytenr, u64 num, int pin, int mark_free);
 int btrfs_drop_leaf_ref(struct btrfs_trans_handle *trans,
                         struct btrfs_root *root, struct extent_buffer *leaf);
 int btrfs_cross_ref_exist(struct btrfs_trans_handle *trans,
@@ -1996,6 +2011,7 @@ void btrfs_delalloc_reserve_space(struct btrfs_root *root, struct inode *inode,
                                  u64 bytes);
 void btrfs_delalloc_free_space(struct btrfs_root *root, struct inode *inode,
                               u64 bytes);
+void btrfs_free_super_mirror_extents(struct btrfs_fs_info *info);
 /* ctree.c */
 int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key,
                      int level, int *slot);
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 55d9d188e693..ec2c915f7f4a 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -907,6 +907,7 @@ static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
         spin_lock_init(&root->inode_lock);
         mutex_init(&root->objectid_mutex);
         mutex_init(&root->log_mutex);
+        init_rwsem(&root->commit_root_sem);
         init_waitqueue_head(&root->log_writer_wait);
         init_waitqueue_head(&root->log_commit_wait[0]);
         init_waitqueue_head(&root->log_commit_wait[1]);
@@ -1566,6 +1567,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         atomic_set(&fs_info->async_delalloc_pages, 0);
         atomic_set(&fs_info->async_submit_draining, 0);
         atomic_set(&fs_info->nr_async_bios, 0);
+        atomic_set(&fs_info->async_caching_threads, 0);
         fs_info->sb = sb;
         fs_info->max_extent = (u64)-1;
         fs_info->max_inline = 8192 * 1024;
@@ -2337,6 +2339,7 @@ int close_ctree(struct btrfs_root *root)
         free_extent_buffer(root->fs_info->csum_root->commit_root);
 
         btrfs_free_block_groups(root->fs_info);
+        btrfs_free_super_mirror_extents(root->fs_info);
 
         del_fs_roots(fs_info);
 
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 98697be6bdde..9a489cc89fd3 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -21,6 +21,7 @@
 #include <linux/blkdev.h>
 #include <linux/sort.h>
 #include <linux/rcupdate.h>
+#include <linux/kthread.h>
 #include "compat.h"
 #include "hash.h"
 #include "ctree.h"
@@ -61,6 +62,13 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
                           struct btrfs_root *extent_root, u64 alloc_bytes,
                           u64 flags, int force);
 
+static noinline int
+block_group_cache_done(struct btrfs_block_group_cache *cache)
+{
+        smp_mb();
+        return cache->cached == BTRFS_CACHE_FINISHED;
+}
+
 static int block_group_bits(struct btrfs_block_group_cache *cache, u64 bits)
 {
         return (cache->flags & bits) == bits;
@@ -145,21 +153,64 @@ block_group_cache_tree_search(struct btrfs_fs_info *info, u64 bytenr,
         return ret;
 }
 
+void btrfs_free_super_mirror_extents(struct btrfs_fs_info *info)
+{
+        u64 start, end, last = 0;
+        int ret;
+
+        while (1) {
+                ret = find_first_extent_bit(&info->pinned_extents, last,
+                                            &start, &end, EXTENT_LOCKED);
+                if (ret)
+                        break;
+
+                unlock_extent(&info->pinned_extents, start, end, GFP_NOFS);
+                last = end+1;
+        }
+}
+
+static int remove_sb_from_cache(struct btrfs_root *root,
+                                struct btrfs_block_group_cache *cache)
+{
+        struct btrfs_fs_info *fs_info = root->fs_info;
+        u64 bytenr;
+        u64 *logical;
+        int stripe_len;
+        int i, nr, ret;
+
+        for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
+                bytenr = btrfs_sb_offset(i);
+                ret = btrfs_rmap_block(&root->fs_info->mapping_tree,
+                                       cache->key.objectid, bytenr,
+                                       0, &logical, &nr, &stripe_len);
+                BUG_ON(ret);
+                while (nr--) {
+                        try_lock_extent(&fs_info->pinned_extents,
+                                        logical[nr],
+                                        logical[nr] + stripe_len - 1, GFP_NOFS);
+                }
+                kfree(logical);
+        }
+
+        return 0;
+}
+
 /*
  * this is only called by cache_block_group, since we could have freed extents
  * we need to check the pinned_extents for any extents that can't be used yet
  * since their free space will be released as soon as the transaction commits.
  */
-static int add_new_free_space(struct btrfs_block_group_cache *block_group,
+static u64 add_new_free_space(struct btrfs_block_group_cache *block_group,
                               struct btrfs_fs_info *info, u64 start, u64 end)
 {
-        u64 extent_start, extent_end, size;
+        u64 extent_start, extent_end, size, total_added = 0;
         int ret;
 
         while (start < end) {
                 ret = find_first_extent_bit(&info->pinned_extents, start,
                                             &extent_start, &extent_end,
-                                            EXTENT_DIRTY);
+                                            EXTENT_DIRTY|EXTENT_LOCKED|
+                                            EXTENT_DELALLOC);
                 if (ret)
                         break;
 
@@ -167,6 +218,7 @@ static int add_new_free_space(struct btrfs_block_group_cache *block_group,
                         start = extent_end + 1;
                 } else if (extent_start > start && extent_start < end) {
                         size = extent_start - start;
+                        total_added += size;
                         ret = btrfs_add_free_space(block_group, start,
                                                    size);
                         BUG_ON(ret);
@@ -178,84 +230,139 @@ static int add_new_free_space(struct btrfs_block_group_cache *block_group,
 
         if (start < end) {
                 size = end - start;
+                total_added += size;
                 ret = btrfs_add_free_space(block_group, start, size);
                 BUG_ON(ret);
         }
 
-        return 0;
+        return total_added;
 }
 
-static int remove_sb_from_cache(struct btrfs_root *root,
-                                struct btrfs_block_group_cache *cache)
+DEFINE_MUTEX(discard_mutex);
+
+/*
+ * if async kthreads are running when we cross transactions, we mark any pinned
+ * extents with EXTENT_DELALLOC and then let the caching kthreads clean up those
+ * extents when they are done.  Also we run this from btrfs_finish_extent_commit
+ * in case there were some pinned extents that were missed because we had
+ * already cached that block group.
+ */
+static void btrfs_discard_pinned_extents(struct btrfs_fs_info *fs_info,
+                                         struct btrfs_block_group_cache *cache)
 {
-        u64 bytenr;
-        u64 *logical;
-        int stripe_len;
-        int i, nr, ret;
+        u64 start, end, last;
+        int ret;
 
-        for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
-                bytenr = btrfs_sb_offset(i);
-                ret = btrfs_rmap_block(&root->fs_info->mapping_tree,
-                                       cache->key.objectid, bytenr, 0,
-                                       &logical, &nr, &stripe_len);
-                BUG_ON(ret);
-                while (nr--) {
-                        btrfs_remove_free_space(cache, logical[nr],
-                                                stripe_len);
+        if (!cache)
+                last = 0;
+        else
+                last = cache->key.objectid;
+
+        mutex_lock(&discard_mutex);
+        while (1) {
+                ret = find_first_extent_bit(&fs_info->pinned_extents, last,
+                                            &start, &end, EXTENT_DELALLOC);
+                if (ret)
+                        break;
+
+                if (cache && start >= cache->key.objectid + cache->key.offset)
+                        break;
+
+
+                if (!cache) {
+                        cache = btrfs_lookup_block_group(fs_info, start);
+                        BUG_ON(!cache);
+
+                        start = max(start, cache->key.objectid);
+                        end = min(end, cache->key.objectid + cache->key.offset - 1);
+
+                        if (block_group_cache_done(cache))
+                                btrfs_add_free_space(cache, start,
+                                                     end - start + 1);
+                        cache = NULL;
+                } else {
+                        start = max(start, cache->key.objectid);
+                        end = min(end, cache->key.objectid + cache->key.offset - 1);
+                        btrfs_add_free_space(cache, start, end - start + 1);
+                }
+
+                clear_extent_bits(&fs_info->pinned_extents, start, end,
+                                  EXTENT_DELALLOC, GFP_NOFS);
+                last = end + 1;
+
+                if (need_resched()) {
+                        mutex_unlock(&discard_mutex);
+                        cond_resched();
+                        mutex_lock(&discard_mutex);
                 }
-                kfree(logical);
         }
-        return 0;
+        mutex_unlock(&discard_mutex);
 }
 
-static int cache_block_group(struct btrfs_root *root,
-                             struct btrfs_block_group_cache *block_group)
+static int caching_kthread(void *data)
 {
+        struct btrfs_block_group_cache *block_group = data;
+        struct btrfs_fs_info *fs_info = block_group->fs_info;
+        u64 last = 0;
         struct btrfs_path *path;
         int ret = 0;
         struct btrfs_key key;
         struct extent_buffer *leaf;
         int slot;
-        u64 last;
-
-        if (!block_group)
-                return 0;
+        u64 total_found = 0;
 
-        root = root->fs_info->extent_root;
-
-        if (block_group->cached)
-                return 0;
+        BUG_ON(!fs_info);
 
         path = btrfs_alloc_path();
         if (!path)
                 return -ENOMEM;
 
-        path->reada = 2;
+        atomic_inc(&fs_info->async_caching_threads);
+        atomic_inc(&block_group->space_info->caching_threads);
+        last = max_t(u64, block_group->key.objectid, BTRFS_SUPER_INFO_OFFSET);
+again:
+        /* need to make sure the commit_root doesn't disappear */
+        down_read(&fs_info->extent_root->commit_root_sem);
+
         /*
-         * we get into deadlocks with paths held by callers of this function.
-         * since the alloc_mutex is protecting things right now, just
-         * skip the locking here
+         * We don't want to deadlock with somebody trying to allocate a new
+         * extent for the extent root while also trying to search the extent
+         * root to add free space.  So we skip locking and search the commit
+         * root, since its read-only
          */
         path->skip_locking = 1;
-        last = max_t(u64, block_group->key.objectid, BTRFS_SUPER_INFO_OFFSET);
+        path->search_commit_root = 1;
+        path->reada = 2;
+
         key.objectid = last;
         key.offset = 0;
         btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
-        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+        ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
         if (ret < 0)
                 goto err;
 
         while (1) {
+                smp_mb();
+                if (block_group->fs_info->closing)
+                        break;
+
                 leaf = path->nodes[0];
                 slot = path->slots[0];
                 if (slot >= btrfs_header_nritems(leaf)) {
-                        ret = btrfs_next_leaf(root, path);
+                        ret = btrfs_next_leaf(fs_info->extent_root, path);
                         if (ret < 0)
                                 goto err;
-                        if (ret == 0)
-                                continue;
-                        else
+                        else if (ret)
                                 break;
+
+                        if (need_resched()) {
+                                btrfs_release_path(fs_info->extent_root, path);
+                                up_read(&fs_info->extent_root->commit_root_sem);
+                                cond_resched();
+                                goto again;
+                        }
+
+                        continue;
                 }
                 btrfs_item_key_to_cpu(leaf, &key, slot);
                 if (key.objectid < block_group->key.objectid)
@@ -266,24 +373,63 @@ static int cache_block_group(struct btrfs_root *root,
                         break;
 
                 if (btrfs_key_type(&key) == BTRFS_EXTENT_ITEM_KEY) {
-                        add_new_free_space(block_group, root->fs_info, last,
-                                           key.objectid);
-
+                        total_found += add_new_free_space(block_group,
+                                                          fs_info, last,
+                                                          key.objectid);
                         last = key.objectid + key.offset;
                 }
+
+                if (total_found > (1024 * 1024 * 2)) {
+                        total_found = 0;
+                        wake_up(&block_group->caching_q);
+                }
 next:
                 path->slots[0]++;
         }
+        ret = 0;
 
-        add_new_free_space(block_group, root->fs_info, last,
-                           block_group->key.objectid +
-                           block_group->key.offset);
+        total_found += add_new_free_space(block_group, fs_info, last,
+                                          block_group->key.objectid +
+                                          block_group->key.offset);
+
+        spin_lock(&block_group->lock);
+        block_group->cached = BTRFS_CACHE_FINISHED;
+        spin_unlock(&block_group->lock);
 
-        block_group->cached = 1;
-        remove_sb_from_cache(root, block_group);
-        ret = 0;
 err:
         btrfs_free_path(path);
+        up_read(&fs_info->extent_root->commit_root_sem);
+        atomic_dec(&fs_info->async_caching_threads);
+        atomic_dec(&block_group->space_info->caching_threads);
+        wake_up(&block_group->caching_q);
+
+        if (!ret)
+                btrfs_discard_pinned_extents(fs_info, block_group);
+
+        return 0;
+}
+
+static int cache_block_group(struct btrfs_block_group_cache *cache)
+{
+        struct task_struct *tsk;
+        int ret = 0;
+
+        spin_lock(&cache->lock);
+        if (cache->cached != BTRFS_CACHE_NO) {
+                spin_unlock(&cache->lock);
+                return ret;
+        }
+        cache->cached = BTRFS_CACHE_STARTED;
+        spin_unlock(&cache->lock);
+
+        tsk = kthread_run(caching_kthread, cache, "btrfs-cache-%llu\n",
+                          cache->key.objectid);
+        if (IS_ERR(tsk)) {
+                ret = PTR_ERR(tsk);
+                printk(KERN_ERR "error running thread %d\n", ret);
+                BUG();
+        }
+
         return ret;
 }
 
@@ -1721,7 +1867,7 @@ static int run_one_delayed_ref(struct btrfs_trans_handle *trans,
                                 BUG_ON(ret);
                         }
                         btrfs_update_pinned_extents(root, node->bytenr,
-                                                    node->num_bytes, 1);
+                                                    node->num_bytes, 1, 0);
                         update_reserved_extents(root, node->bytenr,
                                                 node->num_bytes, 0);
                 }
@@ -2496,6 +2642,7 @@ static int update_space_info(struct btrfs_fs_info *info, u64 flags,
         found->force_alloc = 0;
         *space_info = found;
         list_add_rcu(&found->list, &info->space_info);
+        atomic_set(&found->caching_threads, 0);
         return 0;
 }
 
@@ -2953,7 +3100,7 @@ static u64 first_logical_byte(struct btrfs_root *root, u64 search_start)
 }
 
 int btrfs_update_pinned_extents(struct btrfs_root *root,
-                                u64 bytenr, u64 num, int pin)
+                                u64 bytenr, u64 num, int pin, int mark_free)
 {
         u64 len;
         struct btrfs_block_group_cache *cache;
@@ -2988,7 +3135,7 @@ int btrfs_update_pinned_extents(struct btrfs_root *root,
                         spin_unlock(&cache->lock);
                         spin_unlock(&cache->space_info->lock);
                         fs_info->total_pinned -= len;
-                        if (cache->cached)
+                        if (block_group_cache_done(cache) && mark_free)
                                 btrfs_add_free_space(cache, bytenr, len);
                 }
                 btrfs_put_block_group(cache);
@@ -3034,14 +3181,27 @@ int btrfs_copy_pinned(struct btrfs_root *root, struct extent_io_tree *copy)
         u64 last = 0;
         u64 start;
         u64 end;
+        bool caching_kthreads = false;
         struct extent_io_tree *pinned_extents = &root->fs_info->pinned_extents;
         int ret;
 
+        if (atomic_read(&root->fs_info->async_caching_threads))
+                caching_kthreads = true;
+
         while (1) {
                 ret = find_first_extent_bit(pinned_extents, last,
                                             &start, &end, EXTENT_DIRTY);
                 if (ret)
                         break;
+
+                /*
+                 * we need to make sure that the pinned extents don't go away
+                 * while we are caching block groups
+                 */
+                if (unlikely(caching_kthreads))
+                        set_extent_delalloc(pinned_extents, start, end,
+                                            GFP_NOFS);
+
                 set_extent_dirty(copy, start, end, GFP_NOFS);
                 last = end + 1;
         }
@@ -3055,6 +3215,12 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
         u64 start;
         u64 end;
         int ret;
+        int mark_free = 1;
+
+        ret = find_first_extent_bit(&root->fs_info->pinned_extents, 0,
+                                    &start, &end, EXTENT_DELALLOC);
+        if (!ret)
+                mark_free = 0;
 
         while (1) {
                 ret = find_first_extent_bit(unpin, 0, &start, &end,
@@ -3065,11 +3231,16 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
                 ret = btrfs_discard_extent(root, start, end + 1 - start);
 
                 /* unlocks the pinned mutex */
-                btrfs_update_pinned_extents(root, start, end + 1 - start, 0);
+                btrfs_update_pinned_extents(root, start, end + 1 - start, 0,
+                                            mark_free);
                 clear_extent_dirty(unpin, start, end, GFP_NOFS);
 
                 cond_resched();
         }
+
+        if (unlikely(!mark_free))
+                btrfs_discard_pinned_extents(root->fs_info, NULL);
+
         return ret;
 }
 
@@ -3110,7 +3281,7 @@ static int pin_down_bytes(struct btrfs_trans_handle *trans,
 pinit:
         btrfs_set_path_blocking(path);
         /* unlocks the pinned mutex */
-        btrfs_update_pinned_extents(root, bytenr, num_bytes, 1);
+        btrfs_update_pinned_extents(root, bytenr, num_bytes, 1, 0);
 
         BUG_ON(err < 0);
         return 0;
@@ -3421,7 +3592,7 @@ int btrfs_free_extent(struct btrfs_trans_handle *trans,
         if (root_objectid == BTRFS_TREE_LOG_OBJECTID) {
                 WARN_ON(owner >= BTRFS_FIRST_FREE_OBJECTID);
                 /* unlocks the pinned mutex */
-                btrfs_update_pinned_extents(root, bytenr, num_bytes, 1);
+                btrfs_update_pinned_extents(root, bytenr, num_bytes, 1, 0);
                 update_reserved_extents(root, bytenr, num_bytes, 0);
                 ret = 0;
         } else if (owner < BTRFS_FIRST_FREE_OBJECTID) {
@@ -3448,6 +3619,45 @@ static u64 stripe_align(struct btrfs_root *root, u64 val)
 }
 
 /*
+ * when we wait for progress in the block group caching, its because
+ * our allocation attempt failed at least once.  So, we must sleep
+ * and let some progress happen before we try again.
+ *
+ * This function will sleep at least once waiting for new free space to
+ * show up, and then it will check the block group free space numbers
+ * for our min num_bytes.  Another option is to have it go ahead
+ * and look in the rbtree for a free extent of a given size, but this
+ * is a good start.
+ */
+static noinline int
+wait_block_group_cache_progress(struct btrfs_block_group_cache *cache,
+                                u64 num_bytes)
+{
+        DEFINE_WAIT(wait);
+
+        prepare_to_wait(&cache->caching_q, &wait, TASK_UNINTERRUPTIBLE);
+
+        if (block_group_cache_done(cache)) {
+                finish_wait(&cache->caching_q, &wait);
+                return 0;
+        }
+        schedule();
+        finish_wait(&cache->caching_q, &wait);
+
+        wait_event(cache->caching_q, block_group_cache_done(cache) ||
+                   (cache->free_space >= num_bytes));
+        return 0;
+}
+
+enum btrfs_loop_type {
+        LOOP_CACHED_ONLY = 0,
+        LOOP_CACHING_NOWAIT = 1,
+        LOOP_CACHING_WAIT = 2,
+        LOOP_ALLOC_CHUNK = 3,
+        LOOP_NO_EMPTY_SIZE = 4,
+};
+
+/*
  * walks the btree of allocated extents and find a hole of a given size.
  * The key ins is changed to record the hole:
  * ins->objectid == block start
@@ -3472,6 +3682,7 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans,
         struct btrfs_space_info *space_info;
         int last_ptr_loop = 0;
         int loop = 0;
+        bool found_uncached_bg = false;
 
         WARN_ON(num_bytes < root->sectorsize);
         btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
@@ -3503,15 +3714,18 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans,
         search_start = max(search_start, first_logical_byte(root, 0));
         search_start = max(search_start, hint_byte);
 
-        if (!last_ptr) {
+        if (!last_ptr)
                 empty_cluster = 0;
-                loop = 1;
-        }
 
         if (search_start == hint_byte) {
                 block_group = btrfs_lookup_block_group(root->fs_info,
                                                        search_start);
-                if (block_group && block_group_bits(block_group, data)) {
+                /*
+                 * we don't want to use the block group if it doesn't match our
+                 * allocation bits, or if its not cached.
+                 */
+                if (block_group && block_group_bits(block_group, data) &&
+                    block_group_cache_done(block_group)) {
                         down_read(&space_info->groups_sem);
                         if (list_empty(&block_group->list) ||
                             block_group->ro) {
@@ -3534,21 +3748,35 @@ search:
         down_read(&space_info->groups_sem);
         list_for_each_entry(block_group, &space_info->block_groups, list) {
                 u64 offset;
+                int cached;
 
                 atomic_inc(&block_group->count);
                 search_start = block_group->key.objectid;
 
 have_block_group:
-                if (unlikely(!block_group->cached)) {
-                        mutex_lock(&block_group->cache_mutex);
-                        ret = cache_block_group(root, block_group);
-                        mutex_unlock(&block_group->cache_mutex);
-                        if (ret) {
-                                btrfs_put_block_group(block_group);
-                                break;
+                if (unlikely(block_group->cached == BTRFS_CACHE_NO)) {
+                        /*
+                         * we want to start caching kthreads, but not too many
+                         * right off the bat so we don't overwhelm the system,
+                         * so only start them if there are less than 2 and we're
+                         * in the initial allocation phase.
+                         */
+                        if (loop > LOOP_CACHING_NOWAIT ||
+                            atomic_read(&space_info->caching_threads) < 2) {
+                                ret = cache_block_group(block_group);
+                                BUG_ON(ret);
                         }
                 }
 
+                cached = block_group_cache_done(block_group);
+                if (unlikely(!cached)) {
+                        found_uncached_bg = true;
+
+                        /* if we only want cached bgs, loop */
+                        if (loop == LOOP_CACHED_ONLY)
+                                goto loop;
+                }
+
                 if (unlikely(block_group->ro))
                         goto loop;
 
@@ -3627,14 +3855,21 @@ refill_cluster:
                                         spin_unlock(&last_ptr->refill_lock);
                                         goto checks;
                                 }
+                        } else if (!cached && loop > LOOP_CACHING_NOWAIT) {
+                                spin_unlock(&last_ptr->refill_lock);
+
+                                wait_block_group_cache_progress(block_group,
+                                       num_bytes + empty_cluster + empty_size);
+                                goto have_block_group;
                         }
+
                         /*
                          * at this point we either didn't find a cluster
                          * or we weren't able to allocate a block from our
                          * cluster.  Free the cluster we've been trying
                          * to use, and go to the next block group
                          */
-                        if (loop < 2) {
+                        if (loop < LOOP_NO_EMPTY_SIZE) {
                                 btrfs_return_cluster_to_free_space(NULL,
                                                                    last_ptr);
                                 spin_unlock(&last_ptr->refill_lock);
@@ -3645,8 +3880,15 @@ refill_cluster:
 
                 offset = btrfs_find_space_for_alloc(block_group, search_start,
                                                     num_bytes, empty_size);
-                if (!offset)
+                if (!offset && (cached || (!cached &&
+                                           loop == LOOP_CACHING_NOWAIT))) {
                         goto loop;
+                } else if (!offset && (!cached &&
+                                       loop > LOOP_CACHING_NOWAIT)) {
+                        wait_block_group_cache_progress(block_group,
+                                        num_bytes + empty_size);
+                        goto have_block_group;
+                }
 checks:
                 search_start = stripe_align(root, offset);
                 /* move on to the next group */
@@ -3694,13 +3936,26 @@ loop:
         }
         up_read(&space_info->groups_sem);
 
-        /* loop == 0, try to find a clustered alloc in every block group
-         * loop == 1, try again after forcing a chunk allocation
-         * loop == 2, set empty_size and empty_cluster to 0 and try again
+        /* LOOP_CACHED_ONLY, only search fully cached block groups
+         * LOOP_CACHING_NOWAIT, search partially cached block groups, but
+         *                      dont wait foR them to finish caching
+         * LOOP_CACHING_WAIT, search everything, and wait if our bg is caching
+         * LOOP_ALLOC_CHUNK, force a chunk allocation and try again
+         * LOOP_NO_EMPTY_SIZE, set empty_size and empty_cluster to 0 and try
+         *                      again
          */
-        if (!ins->objectid && loop < 3 &&
-            (empty_size || empty_cluster || allowed_chunk_alloc)) {
-                if (loop >= 2) {
+        if (!ins->objectid && loop < LOOP_NO_EMPTY_SIZE &&
+            (found_uncached_bg || empty_size || empty_cluster ||
+             allowed_chunk_alloc)) {
+                if (found_uncached_bg) {
+                        found_uncached_bg = false;
+                        if (loop < LOOP_CACHING_WAIT) {
+                                loop++;
+                                goto search;
+                        }
+                }
+
+                if (loop == LOOP_ALLOC_CHUNK) {
                         empty_size = 0;
                         empty_cluster = 0;
                 }
@@ -3713,7 +3968,7 @@ loop:
                         space_info->force_alloc = 1;
                 }
 
-                if (loop < 3) {
+                if (loop < LOOP_NO_EMPTY_SIZE) {
                         loop++;
                         goto search;
                 }
@@ -3809,7 +4064,7 @@ again:
                                num_bytes, data, 1);
                 goto again;
         }
-        if (ret) {
+        if (ret == -ENOSPC) {
                 struct btrfs_space_info *sinfo;
 
                 sinfo = __find_space_info(root->fs_info, data);
@@ -3817,7 +4072,6 @@ again:
                        "wanted %llu\n", (unsigned long long)data,
                        (unsigned long long)num_bytes);
                 dump_space_info(sinfo, num_bytes);
-                BUG();
         }
 
         return ret;
@@ -3855,7 +4109,9 @@ int btrfs_reserve_extent(struct btrfs_trans_handle *trans,
         ret = __btrfs_reserve_extent(trans, root, num_bytes, min_alloc_size,
                                      empty_size, hint_byte, search_end, ins,
                                      data);
-        update_reserved_extents(root, ins->objectid, ins->offset, 1);
+        if (!ret)
+                update_reserved_extents(root, ins->objectid, ins->offset, 1);
+
         return ret;
 }
 
@@ -4017,9 +4273,9 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans,
         struct btrfs_block_group_cache *block_group;
 
         block_group = btrfs_lookup_block_group(root->fs_info, ins->objectid);
-        mutex_lock(&block_group->cache_mutex);
-        cache_block_group(root, block_group);
-        mutex_unlock(&block_group->cache_mutex);
+        cache_block_group(block_group);
+        wait_event(block_group->caching_q,
+                   block_group_cache_done(block_group));
 
         ret = btrfs_remove_free_space(block_group, ins->objectid,
                                       ins->offset);
@@ -4050,7 +4306,8 @@ static int alloc_tree_block(struct btrfs_trans_handle *trans,
         ret = __btrfs_reserve_extent(trans, root, num_bytes, num_bytes,
                                      empty_size, hint_byte, search_end,
                                      ins, 0);
-        BUG_ON(ret);
+        if (ret)
+                return ret;
 
         if (root_objectid == BTRFS_TREE_RELOC_OBJECTID) {
                 if (parent == 0)
@@ -6966,11 +7223,16 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info)
                          &info->block_group_cache_tree);
                 spin_unlock(&info->block_group_cache_lock);
 
-                btrfs_remove_free_space_cache(block_group);
                 down_write(&block_group->space_info->groups_sem);
                 list_del(&block_group->list);
                 up_write(&block_group->space_info->groups_sem);
 
+                if (block_group->cached == BTRFS_CACHE_STARTED)
+                        wait_event(block_group->caching_q,
+                                   block_group_cache_done(block_group));
+
+                btrfs_remove_free_space_cache(block_group);
+
                 WARN_ON(atomic_read(&block_group->count) != 1);
                 kfree(block_group);
 
@@ -7036,10 +7298,10 @@ int btrfs_read_block_groups(struct btrfs_root *root)
                 atomic_set(&cache->count, 1);
                 spin_lock_init(&cache->lock);
                 spin_lock_init(&cache->tree_lock);
-                mutex_init(&cache->cache_mutex);
+                cache->fs_info = info;
+                init_waitqueue_head(&cache->caching_q);
                 INIT_LIST_HEAD(&cache->list);
                 INIT_LIST_HEAD(&cache->cluster_list);
-                cache->sectorsize = root->sectorsize;
 
                 /*
                  * we only want to have 32k of ram per block group for keeping
@@ -7057,6 +7319,26 @@ int btrfs_read_block_groups(struct btrfs_root *root)
                 key.objectid = found_key.objectid + found_key.offset;
                 btrfs_release_path(root, path);
                 cache->flags = btrfs_block_group_flags(&cache->item);
+                cache->sectorsize = root->sectorsize;
+
+                remove_sb_from_cache(root, cache);
+
+                /*
+                 * check for two cases, either we are full, and therefore
+                 * don't need to bother with the caching work since we won't
+                 * find any space, or we are empty, and we can just add all
+                 * the space in and be done with it.  This saves us _alot_ of
+                 * time, particularly in the full case.
+                 */
+                if (found_key.offset == btrfs_block_group_used(&cache->item)) {
+                        cache->cached = BTRFS_CACHE_FINISHED;
+                } else if (btrfs_block_group_used(&cache->item) == 0) {
+                        cache->cached = BTRFS_CACHE_FINISHED;
+                        add_new_free_space(cache, root->fs_info,
+                                           found_key.objectid,
+                                           found_key.objectid +
+                                           found_key.offset);
+                }
 
                 ret = update_space_info(info, cache->flags, found_key.offset,
                                         btrfs_block_group_used(&cache->item),
@@ -7112,7 +7394,7 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
         atomic_set(&cache->count, 1);
         spin_lock_init(&cache->lock);
         spin_lock_init(&cache->tree_lock);
-        mutex_init(&cache->cache_mutex);
+        init_waitqueue_head(&cache->caching_q);
         INIT_LIST_HEAD(&cache->list);
         INIT_LIST_HEAD(&cache->cluster_list);
 
@@ -7121,11 +7403,12 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
         cache->flags = type;
         btrfs_set_block_group_flags(&cache->item, type);
 
-        cache->cached = 1;
-        ret = btrfs_add_free_space(cache, chunk_offset, size);
-        BUG_ON(ret);
+        cache->cached = BTRFS_CACHE_FINISHED;
         remove_sb_from_cache(root, cache);
 
+        add_new_free_space(cache, root->fs_info, chunk_offset,
+                           chunk_offset + size);
+
         ret = update_space_info(root->fs_info, cache->flags, size, bytes_used,
                                 &cache->space_info);
         BUG_ON(ret);
@@ -7184,7 +7467,7 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
         rb_erase(&block_group->cache_node,
                  &root->fs_info->block_group_cache_tree);
         spin_unlock(&root->fs_info->block_group_cache_lock);
-        btrfs_remove_free_space_cache(block_group);
+
         down_write(&block_group->space_info->groups_sem);
         /*
          * we must use list_del_init so people can check to see if they
@@ -7193,6 +7476,12 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
         list_del_init(&block_group->list);
         up_write(&block_group->space_info->groups_sem);
 
+        if (block_group->cached == BTRFS_CACHE_STARTED)
+                wait_event(block_group->caching_q,
+                           block_group_cache_done(block_group));
+
+        btrfs_remove_free_space_cache(block_group);
+
         spin_lock(&block_group->space_info->lock);
         block_group->space_info->total_bytes -= block_group->key.offset;
         block_group->space_info->bytes_readonly -= block_group->key.offset;
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index ab8cad8b46c9..af99b78b288e 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -238,6 +238,7 @@ static void unlink_free_space(struct btrfs_block_group_cache *block_group,
 {
         rb_erase(&info->offset_index, &block_group->free_space_offset);
         block_group->free_extents--;
+        block_group->free_space -= info->bytes;
 }
 
 static int link_free_space(struct btrfs_block_group_cache *block_group,
@@ -251,6 +252,7 @@ static int link_free_space(struct btrfs_block_group_cache *block_group,
         if (ret)
                 return ret;
 
+        block_group->free_space += info->bytes;
         block_group->free_extents++;
         return ret;
 }
@@ -285,36 +287,40 @@ static void recalculate_thresholds(struct btrfs_block_group_cache *block_group)
         }
 }
 
-static void bitmap_clear_bits(struct btrfs_free_space *info, u64 offset, u64 bytes,
-                              u64 sectorsize)
+static void bitmap_clear_bits(struct btrfs_block_group_cache *block_group,
+                              struct btrfs_free_space *info, u64 offset,
+                              u64 bytes)
 {
         unsigned long start, end;
         unsigned long i;
 
-        start = offset_to_bit(info->offset, sectorsize, offset);
-        end = start + bytes_to_bits(bytes, sectorsize);
+        start = offset_to_bit(info->offset, block_group->sectorsize, offset);
+        end = start + bytes_to_bits(bytes, block_group->sectorsize);
         BUG_ON(end > BITS_PER_BITMAP);
 
         for (i = start; i < end; i++)
                 clear_bit(i, info->bitmap);
 
         info->bytes -= bytes;
+        block_group->free_space -= bytes;
 }
 
-static void bitmap_set_bits(struct btrfs_free_space *info, u64 offset, u64 bytes,
-                            u64 sectorsize)
+static void bitmap_set_bits(struct btrfs_block_group_cache *block_group,
+                            struct btrfs_free_space *info, u64 offset,
+                            u64 bytes)
 {
         unsigned long start, end;
         unsigned long i;
 
-        start = offset_to_bit(info->offset, sectorsize, offset);
-        end = start + bytes_to_bits(bytes, sectorsize);
+        start = offset_to_bit(info->offset, block_group->sectorsize, offset);
+        end = start + bytes_to_bits(bytes, block_group->sectorsize);
         BUG_ON(end > BITS_PER_BITMAP);
 
         for (i = start; i < end; i++)
                 set_bit(i, info->bitmap);
 
         info->bytes += bytes;
+        block_group->free_space += bytes;
 }
 
 static int search_bitmap(struct btrfs_block_group_cache *block_group,
@@ -414,13 +420,12 @@ again:
                 (u64)(BITS_PER_BITMAP * block_group->sectorsize) - 1;
 
         if (*offset > bitmap_info->offset && *offset + *bytes > end) {
-                bitmap_clear_bits(bitmap_info, *offset,
-                                  end - *offset + 1, block_group->sectorsize);
+                bitmap_clear_bits(block_group, bitmap_info, *offset,
+                                  end - *offset + 1);
                 *bytes -= end - *offset + 1;
                 *offset = end + 1;
         } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
-                bitmap_clear_bits(bitmap_info, *offset,
-                                  *bytes, block_group->sectorsize);
+                bitmap_clear_bits(block_group, bitmap_info, *offset, *bytes);
                 *bytes = 0;
         }
 
@@ -495,14 +500,13 @@ again:
                 (u64)(BITS_PER_BITMAP * block_group->sectorsize);
 
         if (offset >= bitmap_info->offset && offset + bytes > end) {
-                bitmap_set_bits(bitmap_info, offset, end - offset,
-                                block_group->sectorsize);
+                bitmap_set_bits(block_group, bitmap_info, offset,
+                                end - offset);
                 bytes -= end - offset;
                 offset = end;
                 added = 0;
         } else if (offset >= bitmap_info->offset && offset + bytes <= end) {
-                bitmap_set_bits(bitmap_info, offset, bytes,
-                                block_group->sectorsize);
+                bitmap_set_bits(block_group, bitmap_info, offset, bytes);
                 bytes = 0;
         } else {
                 BUG();
@@ -870,8 +874,7 @@ u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
 
         ret = offset;
         if (entry->bitmap) {
-                bitmap_clear_bits(entry, offset, bytes,
-                                  block_group->sectorsize);
+                bitmap_clear_bits(block_group, entry, offset, bytes);
                 if (!entry->bytes) {
                         unlink_free_space(block_group, entry);
                         kfree(entry->bitmap);
@@ -891,6 +894,7 @@ u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
 
 out:
         spin_unlock(&block_group->tree_lock);
+
         return ret;
 }
 
@@ -967,7 +971,7 @@ static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
                 goto out;
 
         ret = search_start;
-        bitmap_clear_bits(entry, ret, bytes, block_group->sectorsize);
+        bitmap_clear_bits(block_group, entry, ret, bytes);
 out:
         spin_unlock(&cluster->lock);
         spin_unlock(&block_group->tree_lock);
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 81f7124c3051..32454d1c566f 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -40,6 +40,14 @@ static noinline void put_transaction(struct btrfs_transaction *transaction)
         }
 }
 
+static noinline void switch_commit_root(struct btrfs_root *root)
+{
+        down_write(&root->commit_root_sem);
+        free_extent_buffer(root->commit_root);
+        root->commit_root = btrfs_root_node(root);
+        up_write(&root->commit_root_sem);
+}
+
 /*
  * either allocate a new transaction or hop into the existing one
  */
@@ -458,8 +466,7 @@ static int update_cowonly_root(struct btrfs_trans_handle *trans,
                 ret = btrfs_write_dirty_block_groups(trans, root);
                 BUG_ON(ret);
         }
-        free_extent_buffer(root->commit_root);
-        root->commit_root = btrfs_root_node(root);
+        switch_commit_root(root);
         return 0;
 }
 
@@ -537,8 +544,7 @@ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
                         btrfs_update_reloc_root(trans, root);
 
                         if (root->commit_root != root->node) {
-                                free_extent_buffer(root->commit_root);
-                                root->commit_root = btrfs_root_node(root);
+                                switch_commit_root(root);
                                 btrfs_set_root_node(&root->root_item,
                                                     root->node);
                         }
@@ -1002,15 +1008,11 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 
         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
                             root->fs_info->tree_root->node);
-        free_extent_buffer(root->fs_info->tree_root->commit_root);
-        root->fs_info->tree_root->commit_root =
-                                btrfs_root_node(root->fs_info->tree_root);
+        switch_commit_root(root->fs_info->tree_root);
 
         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
                             root->fs_info->chunk_root->node);
-        free_extent_buffer(root->fs_info->chunk_root->commit_root);
-        root->fs_info->chunk_root->commit_root =
-                                btrfs_root_node(root->fs_info->chunk_root);
+        switch_commit_root(root->fs_info->chunk_root);
 
         update_super_roots(root);
 
@@ -1050,6 +1052,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
         cur_trans->commit_done = 1;
 
         root->fs_info->last_trans_committed = cur_trans->transid;
+
         wake_up(&cur_trans->commit_wait);
 
         put_transaction(cur_trans);
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index c13922206d1b..195606862618 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -264,7 +264,7 @@ static int process_one_buffer(struct btrfs_root *log,
 {
         if (wc->pin)
                 btrfs_update_pinned_extents(log->fs_info->extent_root,
-                                            eb->start, eb->len, 1);
+                                            eb->start, eb->len, 1, 0);
 
         if (btrfs_buffer_uptodate(eb, gen)) {
                 if (wc->write)