10 files changed, 678 insertions, 115 deletions

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 82ee56bba299..a54d354cefcb 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -128,6 +128,14 @@ struct btrfs_inode {
         u64 last_unlink_trans;
 
         /*
+         * These two counters are for delalloc metadata reservations.  We keep
+         * track of how many extents we've accounted for vs how many extents we
+         * have.
+         */
+        int delalloc_reserved_extents;
+        int delalloc_extents;
+
+        /*
          * ordered_data_close is set by truncate when a file that used
          * to have good data has been truncated to zero.  When it is set
          * the btrfs file release call will add this inode to the
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 80599b4e42bd..b3959a150c3b 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -675,18 +675,19 @@ struct btrfs_space_info {
                                    current allocations */
         u64 bytes_readonly;     /* total bytes that are read only */
         u64 bytes_super;        /* total bytes reserved for the super blocks */
-
-        /* delalloc accounting */
-        u64 bytes_delalloc;     /* number of bytes reserved for allocation,
-                                   this space is not necessarily reserved yet
-                                   by the allocator */
+        u64 bytes_root;         /* the number of bytes needed to commit a
+                                   transaction */
         u64 bytes_may_use;      /* number of bytes that may be used for
-                                   delalloc */
+                                   delalloc/allocations */
+        u64 bytes_delalloc;     /* number of bytes currently reserved for
+                                   delayed allocation */
 
         int full;               /* indicates that we cannot allocate any more
                                    chunks for this space */
         int force_alloc;        /* set if we need to force a chunk alloc for
                                    this space */
+        int force_delalloc;     /* make people start doing filemap_flush until
+                                   we're under a threshold */
 
         struct list_head list;
 
@@ -695,6 +696,9 @@ struct btrfs_space_info {
         spinlock_t lock;
         struct rw_semaphore groups_sem;
         atomic_t caching_threads;
+
+        int allocating_chunk;
+        wait_queue_head_t wait;
 };
 
 /*
@@ -2022,7 +2026,12 @@ 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_reserve_metadata_space(struct btrfs_root *root, int num_items);
+int btrfs_unreserve_metadata_space(struct btrfs_root *root, int num_items);
+int btrfs_unreserve_metadata_for_delalloc(struct btrfs_root *root,
+                                          struct inode *inode, int num_items);
+int btrfs_reserve_metadata_for_delalloc(struct btrfs_root *root,
+                                        struct inode *inode, int num_items);
 int btrfs_check_data_free_space(struct btrfs_root *root, struct inode *inode,
                                 u64 bytes);
 void btrfs_free_reserved_data_space(struct btrfs_root *root,
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index f1e905f7e701..ece8d1e26b5e 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1629,7 +1629,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         fs_info->sb = sb;
         fs_info->max_extent = (u64)-1;
         fs_info->max_inline = 8192 * 1024;
-        fs_info->metadata_ratio = 8;
+        fs_info->metadata_ratio = 0;
 
         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 90d314eeff6d..a4b2b03cd682 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -68,6 +68,8 @@ static int pin_down_bytes(struct btrfs_trans_handle *trans,
                           struct extent_buffer **must_clean);
 static int find_next_key(struct btrfs_path *path, int level,
                          struct btrfs_key *key);
+static void dump_space_info(struct btrfs_space_info *info, u64 bytes,
+                            int dump_block_groups);
 
 static noinline int
 block_group_cache_done(struct btrfs_block_group_cache *cache)
@@ -2764,67 +2766,346 @@ void btrfs_set_inode_space_info(struct btrfs_root *root, struct inode *inode)
                                                        alloc_target);
 }
 
+static u64 calculate_bytes_needed(struct btrfs_root *root, int num_items)
+{
+        u64 num_bytes;
+        int level;
+
+        level = BTRFS_MAX_LEVEL - 2;
+        /*
+         * NOTE: these calculations are absolutely the worst possible case.
+         * This assumes that _every_ item we insert will require a new leaf, and
+         * that the tree has grown to its maximum level size.
+         */
+
+        /*
+         * for every item we insert we could insert both an extent item and a
+         * extent ref item.  Then for ever item we insert, we will need to cow
+         * both the original leaf, plus the leaf to the left and right of it.
+         *
+         * Unless we are talking about the extent root, then we just want the
+         * number of items * 2, since we just need the extent item plus its ref.
+         */
+        if (root == root->fs_info->extent_root)
+                num_bytes = num_items * 2;
+        else
+                num_bytes = (num_items + (2 * num_items)) * 3;
+
+        /*
+         * num_bytes is total number of leaves we could need times the leaf
+         * size, and then for every leaf we could end up cow'ing 2 nodes per
+         * level, down to the leaf level.
+         */
+        num_bytes = (num_bytes * root->leafsize) +
+                (num_bytes * (level * 2)) * root->nodesize;
+
+        return num_bytes;
+}
+
 /*
- * for now this just makes sure we have at least 5% of our metadata space free
- * for use.
+ * Unreserve metadata space for delalloc.  If we have less reserved credits than
+ * we have extents, this function does nothing.
  */
-int btrfs_check_metadata_free_space(struct btrfs_root *root)
+int btrfs_unreserve_metadata_for_delalloc(struct btrfs_root *root,
+                                          struct inode *inode, int num_items)
 {
         struct btrfs_fs_info *info = root->fs_info;
         struct btrfs_space_info *meta_sinfo;
-        u64 alloc_target, thresh;
-        int committed = 0, ret;
+        u64 num_bytes;
+        u64 alloc_target;
+        bool bug = false;
 
         /* get the space info for where the metadata will live */
         alloc_target = btrfs_get_alloc_profile(root, 0);
         meta_sinfo = __find_space_info(info, alloc_target);
-        if (!meta_sinfo)
-                goto alloc;
 
-again:
+        num_bytes = calculate_bytes_needed(root->fs_info->extent_root,
+                                           num_items);
+
         spin_lock(&meta_sinfo->lock);
-        if (!meta_sinfo->full)
-                thresh = meta_sinfo->total_bytes * 80;
-        else
-                thresh = meta_sinfo->total_bytes * 95;
+        if (BTRFS_I(inode)->delalloc_reserved_extents <=
+            BTRFS_I(inode)->delalloc_extents) {
+                spin_unlock(&meta_sinfo->lock);
+                return 0;
+        }
+
+        BTRFS_I(inode)->delalloc_reserved_extents--;
+        BUG_ON(BTRFS_I(inode)->delalloc_reserved_extents < 0);
+
+        if (meta_sinfo->bytes_delalloc < num_bytes) {
+                bug = true;
+                meta_sinfo->bytes_delalloc = 0;
+        } else {
+                meta_sinfo->bytes_delalloc -= num_bytes;
+        }
+        spin_unlock(&meta_sinfo->lock);
 
+        BUG_ON(bug);
+
+        return 0;
+}
+
+static void check_force_delalloc(struct btrfs_space_info *meta_sinfo)
+{
+        u64 thresh;
+
+        thresh = meta_sinfo->bytes_used + meta_sinfo->bytes_reserved +
+                meta_sinfo->bytes_pinned + meta_sinfo->bytes_readonly +
+                meta_sinfo->bytes_super + meta_sinfo->bytes_root +
+                meta_sinfo->bytes_may_use;
+
+        thresh = meta_sinfo->total_bytes - thresh;
+        thresh *= 80;
         do_div(thresh, 100);
+        if (thresh <= meta_sinfo->bytes_delalloc)
+                meta_sinfo->force_delalloc = 1;
+        else
+                meta_sinfo->force_delalloc = 0;
+}
 
-        if (meta_sinfo->bytes_used + meta_sinfo->bytes_reserved +
-            meta_sinfo->bytes_pinned + meta_sinfo->bytes_readonly +
-            meta_sinfo->bytes_super > thresh) {
-                struct btrfs_trans_handle *trans;
-                if (!meta_sinfo->full) {
-                        meta_sinfo->force_alloc = 1;
+static int maybe_allocate_chunk(struct btrfs_root *root,
+                                 struct btrfs_space_info *info)
+{
+        struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
+        struct btrfs_trans_handle *trans;
+        bool wait = false;
+        int ret = 0;
+        u64 min_metadata;
+        u64 free_space;
+
+        free_space = btrfs_super_total_bytes(disk_super);
+        /*
+         * we allow the metadata to grow to a max of either 5gb or 5% of the
+         * space in the volume.
+         */
+        min_metadata = min((u64)5 * 1024 * 1024 * 1024,
+                             div64_u64(free_space * 5, 100));
+        if (info->total_bytes >= min_metadata) {
+                spin_unlock(&info->lock);
+                return 0;
+        }
+
+        if (info->full) {
+                spin_unlock(&info->lock);
+                return 0;
+        }
+
+        if (!info->allocating_chunk) {
+                info->force_alloc = 1;
+                info->allocating_chunk = 1;
+                init_waitqueue_head(&info->wait);
+        } else {
+                wait = true;
+        }
+
+        spin_unlock(&info->lock);
+
+        if (wait) {
+                wait_event(info->wait,
+                           !info->allocating_chunk);
+                return 1;
+        }
+
+        trans = btrfs_start_transaction(root, 1);
+        if (!trans) {
+                ret = -ENOMEM;
+                goto out;
+        }
+
+        ret = do_chunk_alloc(trans, root->fs_info->extent_root,
+                             4096 + 2 * 1024 * 1024,
+                             info->flags, 0);
+        btrfs_end_transaction(trans, root);
+        if (ret)
+                goto out;
+out:
+        spin_lock(&info->lock);
+        info->allocating_chunk = 0;
+        spin_unlock(&info->lock);
+        wake_up(&info->wait);
+
+        if (ret)
+                return 0;
+        return 1;
+}
+
+/*
+ * Reserve metadata space for delalloc.
+ */
+int btrfs_reserve_metadata_for_delalloc(struct btrfs_root *root,
+                                        struct inode *inode, int num_items)
+{
+        struct btrfs_fs_info *info = root->fs_info;
+        struct btrfs_space_info *meta_sinfo;
+        u64 num_bytes;
+        u64 used;
+        u64 alloc_target;
+        int flushed = 0;
+        int force_delalloc;
+
+        /* get the space info for where the metadata will live */
+        alloc_target = btrfs_get_alloc_profile(root, 0);
+        meta_sinfo = __find_space_info(info, alloc_target);
+
+        num_bytes = calculate_bytes_needed(root->fs_info->extent_root,
+                                           num_items);
+again:
+        spin_lock(&meta_sinfo->lock);
+
+        force_delalloc = meta_sinfo->force_delalloc;
+
+        if (unlikely(!meta_sinfo->bytes_root))
+                meta_sinfo->bytes_root = calculate_bytes_needed(root, 6);
+
+        if (!flushed)
+                meta_sinfo->bytes_delalloc += num_bytes;
+
+        used = meta_sinfo->bytes_used + meta_sinfo->bytes_reserved +
+                meta_sinfo->bytes_pinned + meta_sinfo->bytes_readonly +
+                meta_sinfo->bytes_super + meta_sinfo->bytes_root +
+                meta_sinfo->bytes_may_use + meta_sinfo->bytes_delalloc;
+
+        if (used > meta_sinfo->total_bytes) {
+                flushed++;
+
+                if (flushed == 1) {
+                        if (maybe_allocate_chunk(root, meta_sinfo))
+                                goto again;
+                        flushed++;
+                } else {
                         spin_unlock(&meta_sinfo->lock);
-alloc:
-                        trans = btrfs_start_transaction(root, 1);
-                        if (!trans)
-                                return -ENOMEM;
+                }
 
-                        ret = do_chunk_alloc(trans, root->fs_info->extent_root,
-                                             2 * 1024 * 1024, alloc_target, 0);
-                        btrfs_end_transaction(trans, root);
-                        if (!meta_sinfo) {
-                                meta_sinfo = __find_space_info(info,
-                                                               alloc_target);
-                        }
+                if (flushed == 2) {
+                        filemap_flush(inode->i_mapping);
+                        goto again;
+                } else if (flushed == 3) {
+                        btrfs_start_delalloc_inodes(root);
+                        btrfs_wait_ordered_extents(root, 0);
                         goto again;
                 }
+                spin_lock(&meta_sinfo->lock);
+                meta_sinfo->bytes_delalloc -= num_bytes;
                 spin_unlock(&meta_sinfo->lock);
+                printk(KERN_ERR "enospc, has %d, reserved %d\n",
+                       BTRFS_I(inode)->delalloc_extents,
+                       BTRFS_I(inode)->delalloc_reserved_extents);
+                dump_space_info(meta_sinfo, 0, 0);
+                return -ENOSPC;
+        }
 
-                if (!committed) {
-                        committed = 1;
-                        trans = btrfs_join_transaction(root, 1);
-                        if (!trans)
-                                return -ENOMEM;
-                        ret = btrfs_commit_transaction(trans, root);
-                        if (ret)
-                                return ret;
+        BTRFS_I(inode)->delalloc_reserved_extents++;
+        check_force_delalloc(meta_sinfo);
+        spin_unlock(&meta_sinfo->lock);
+
+        if (!flushed && force_delalloc)
+                filemap_flush(inode->i_mapping);
+
+        return 0;
+}
+
+/*
+ * unreserve num_items number of items worth of metadata space.  This needs to
+ * be paired with btrfs_reserve_metadata_space.
+ *
+ * NOTE: if you have the option, run this _AFTER_ you do a
+ * btrfs_end_transaction, since btrfs_end_transaction will run delayed ref
+ * oprations which will result in more used metadata, so we want to make sure we
+ * can do that without issue.
+ */
+int btrfs_unreserve_metadata_space(struct btrfs_root *root, int num_items)
+{
+        struct btrfs_fs_info *info = root->fs_info;
+        struct btrfs_space_info *meta_sinfo;
+        u64 num_bytes;
+        u64 alloc_target;
+        bool bug = false;
+
+        /* get the space info for where the metadata will live */
+        alloc_target = btrfs_get_alloc_profile(root, 0);
+        meta_sinfo = __find_space_info(info, alloc_target);
+
+        num_bytes = calculate_bytes_needed(root, num_items);
+
+        spin_lock(&meta_sinfo->lock);
+        if (meta_sinfo->bytes_may_use < num_bytes) {
+                bug = true;
+                meta_sinfo->bytes_may_use = 0;
+        } else {
+                meta_sinfo->bytes_may_use -= num_bytes;
+        }
+        spin_unlock(&meta_sinfo->lock);
+
+        BUG_ON(bug);
+
+        return 0;
+}
+
+/*
+ * Reserve some metadata space for use.  We'll calculate the worste case number
+ * of bytes that would be needed to modify num_items number of items.  If we
+ * have space, fantastic, if not, you get -ENOSPC.  Please call
+ * btrfs_unreserve_metadata_space when you are done for the _SAME_ number of
+ * items you reserved, since whatever metadata you needed should have already
+ * been allocated.
+ *
+ * This will commit the transaction to make more space if we don't have enough
+ * metadata space.  THe only time we don't do this is if we're reserving space
+ * inside of a transaction, then we will just return -ENOSPC and it is the
+ * callers responsibility to handle it properly.
+ */
+int btrfs_reserve_metadata_space(struct btrfs_root *root, int num_items)
+{
+        struct btrfs_fs_info *info = root->fs_info;
+        struct btrfs_space_info *meta_sinfo;
+        u64 num_bytes;
+        u64 used;
+        u64 alloc_target;
+        int retries = 0;
+
+        /* get the space info for where the metadata will live */
+        alloc_target = btrfs_get_alloc_profile(root, 0);
+        meta_sinfo = __find_space_info(info, alloc_target);
+
+        num_bytes = calculate_bytes_needed(root, num_items);
+again:
+        spin_lock(&meta_sinfo->lock);
+
+        if (unlikely(!meta_sinfo->bytes_root))
+                meta_sinfo->bytes_root = calculate_bytes_needed(root, 6);
+
+        if (!retries)
+                meta_sinfo->bytes_may_use += num_bytes;
+
+        used = meta_sinfo->bytes_used + meta_sinfo->bytes_reserved +
+                meta_sinfo->bytes_pinned + meta_sinfo->bytes_readonly +
+                meta_sinfo->bytes_super + meta_sinfo->bytes_root +
+                meta_sinfo->bytes_may_use + meta_sinfo->bytes_delalloc;
+
+        if (used > meta_sinfo->total_bytes) {
+                retries++;
+                if (retries == 1) {
+                        if (maybe_allocate_chunk(root, meta_sinfo))
+                                goto again;
+                        retries++;
+                } else {
+                        spin_unlock(&meta_sinfo->lock);
+                }
+
+                if (retries == 2) {
+                        btrfs_start_delalloc_inodes(root);
+                        btrfs_wait_ordered_extents(root, 0);
                         goto again;
                 }
+                spin_lock(&meta_sinfo->lock);
+                meta_sinfo->bytes_may_use -= num_bytes;
+                spin_unlock(&meta_sinfo->lock);
+
+                dump_space_info(meta_sinfo, 0, 0);
                 return -ENOSPC;
         }
+
+        check_force_delalloc(meta_sinfo);
         spin_unlock(&meta_sinfo->lock);
 
         return 0;
@@ -2915,7 +3196,7 @@ alloc:
         BTRFS_I(inode)->reserved_bytes += bytes;
         spin_unlock(&data_sinfo->lock);
 
-        return btrfs_check_metadata_free_space(root);
+        return 0;
 }
 
 /*
@@ -3014,17 +3295,15 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
         BUG_ON(!space_info);
 
         spin_lock(&space_info->lock);
-        if (space_info->force_alloc) {
+        if (space_info->force_alloc)
                 force = 1;
-                space_info->force_alloc = 0;
-        }
         if (space_info->full) {
                 spin_unlock(&space_info->lock);
                 goto out;
         }
 
         thresh = space_info->total_bytes - space_info->bytes_readonly;
-        thresh = div_factor(thresh, 6);
+        thresh = div_factor(thresh, 8);
         if (!force &&
            (space_info->bytes_used + space_info->bytes_pinned +
             space_info->bytes_reserved + alloc_bytes) < thresh) {
@@ -3038,7 +3317,7 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
          * we keep a reasonable number of metadata chunks allocated in the
          * FS as well.
          */
-        if (flags & BTRFS_BLOCK_GROUP_DATA) {
+        if (flags & BTRFS_BLOCK_GROUP_DATA && fs_info->metadata_ratio) {
                 fs_info->data_chunk_allocations++;
                 if (!(fs_info->data_chunk_allocations %
                       fs_info->metadata_ratio))
@@ -3046,8 +3325,11 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
         }
 
         ret = btrfs_alloc_chunk(trans, extent_root, flags);
+        spin_lock(&space_info->lock);
         if (ret)
                 space_info->full = 1;
+        space_info->force_alloc = 0;
+        spin_unlock(&space_info->lock);
 out:
         mutex_unlock(&extent_root->fs_info->chunk_mutex);
         return ret;
@@ -4062,21 +4344,32 @@ loop:
         return ret;
 }
 
-static void dump_space_info(struct btrfs_space_info *info, u64 bytes)
+static void dump_space_info(struct btrfs_space_info *info, u64 bytes,
+                            int dump_block_groups)
 {
         struct btrfs_block_group_cache *cache;
 
+        spin_lock(&info->lock);
         printk(KERN_INFO "space_info has %llu free, is %sfull\n",
                (unsigned long long)(info->total_bytes - info->bytes_used -
-                                    info->bytes_pinned - info->bytes_reserved),
+                                    info->bytes_pinned - info->bytes_reserved -
+                                    info->bytes_super),
                (info->full) ? "" : "not ");
         printk(KERN_INFO "space_info total=%llu, pinned=%llu, delalloc=%llu,"
-               " may_use=%llu, used=%llu\n",
+               " may_use=%llu, used=%llu, root=%llu, super=%llu, reserved=%llu"
+               "\n",
                (unsigned long long)info->total_bytes,
                (unsigned long long)info->bytes_pinned,
                (unsigned long long)info->bytes_delalloc,
                (unsigned long long)info->bytes_may_use,
-               (unsigned long long)info->bytes_used);
+               (unsigned long long)info->bytes_used,
+               (unsigned long long)info->bytes_root,
+               (unsigned long long)info->bytes_super,
+               (unsigned long long)info->bytes_reserved);
+        spin_unlock(&info->lock);
+
+        if (!dump_block_groups)
+                return;
 
         down_read(&info->groups_sem);
         list_for_each_entry(cache, &info->block_groups, list) {
@@ -4144,7 +4437,7 @@ again:
                 printk(KERN_ERR "btrfs allocation failed flags %llu, "
                        "wanted %llu\n", (unsigned long long)data,
                        (unsigned long long)num_bytes);
-                dump_space_info(sinfo, num_bytes);
+                dump_space_info(sinfo, num_bytes, 1);
         }
 
         return ret;
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 0cb88f8146ea..de1793ba004a 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -280,6 +280,14 @@ static struct extent_buffer *buffer_search(struct extent_io_tree *tree,
         return NULL;
 }
 
+static void merge_cb(struct extent_io_tree *tree, struct extent_state *new,
+                     struct extent_state *other)
+{
+        if (tree->ops && tree->ops->merge_extent_hook)
+                tree->ops->merge_extent_hook(tree->mapping->host, new,
+                                             other);
+}
+
 /*
  * utility function to look for merge candidates inside a given range.
  * Any extents with matching state are merged together into a single
@@ -303,6 +311,7 @@ static int merge_state(struct extent_io_tree *tree,
                 other = rb_entry(other_node, struct extent_state, rb_node);
                 if (other->end == state->start - 1 &&
                     other->state == state->state) {
+                        merge_cb(tree, state, other);
                         state->start = other->start;
                         other->tree = NULL;
                         rb_erase(&other->rb_node, &tree->state);
@@ -314,33 +323,37 @@ static int merge_state(struct extent_io_tree *tree,
                 other = rb_entry(other_node, struct extent_state, rb_node);
                 if (other->start == state->end + 1 &&
                     other->state == state->state) {
+                        merge_cb(tree, state, other);
                         other->start = state->start;
                         state->tree = NULL;
                         rb_erase(&state->rb_node, &tree->state);
                         free_extent_state(state);
+                        state = NULL;
                 }
         }
+
         return 0;
 }
 
-static void set_state_cb(struct extent_io_tree *tree,
+static int set_state_cb(struct extent_io_tree *tree,
                          struct extent_state *state,
                          unsigned long bits)
 {
         if (tree->ops && tree->ops->set_bit_hook) {
-                tree->ops->set_bit_hook(tree->mapping->host, state->start,
-                                        state->end, state->state, bits);
+                return tree->ops->set_bit_hook(tree->mapping->host,
+                                               state->start, state->end,
+                                               state->state, bits);
         }
+
+        return 0;
 }
 
 static void clear_state_cb(struct extent_io_tree *tree,
                            struct extent_state *state,
                            unsigned long bits)
 {
-        if (tree->ops && tree->ops->clear_bit_hook) {
-                tree->ops->clear_bit_hook(tree->mapping->host, state->start,
-                                          state->end, state->state, bits);
-        }
+        if (tree->ops && tree->ops->clear_bit_hook)
+                tree->ops->clear_bit_hook(tree->mapping->host, state, bits);
 }
 
 /*
@@ -358,6 +371,7 @@ static int insert_state(struct extent_io_tree *tree,
                         int bits)
 {
         struct rb_node *node;
+        int ret;
 
         if (end < start) {
                 printk(KERN_ERR "btrfs end < start %llu %llu\n",
@@ -365,11 +379,14 @@ static int insert_state(struct extent_io_tree *tree,
                        (unsigned long long)start);
                 WARN_ON(1);
         }
-        if (bits & EXTENT_DIRTY)
-                tree->dirty_bytes += end - start + 1;
         state->start = start;
         state->end = end;
-        set_state_cb(tree, state, bits);
+        ret = set_state_cb(tree, state, bits);
+        if (ret)
+                return ret;
+
+        if (bits & EXTENT_DIRTY)
+                tree->dirty_bytes += end - start + 1;
         state->state |= bits;
         node = tree_insert(&tree->state, end, &state->rb_node);
         if (node) {
@@ -387,6 +404,15 @@ static int insert_state(struct extent_io_tree *tree,
         return 0;
 }
 
+static int split_cb(struct extent_io_tree *tree, struct extent_state *orig,
+                     u64 split)
+{
+        if (tree->ops && tree->ops->split_extent_hook)
+                return tree->ops->split_extent_hook(tree->mapping->host,
+                                                    orig, split);
+        return 0;
+}
+
 /*
  * split a given extent state struct in two, inserting the preallocated
  * struct 'prealloc' as the newly created second half.  'split' indicates an
@@ -405,6 +431,9 @@ static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
                        struct extent_state *prealloc, u64 split)
 {
         struct rb_node *node;
+
+        split_cb(tree, orig, split);
+
         prealloc->start = orig->start;
         prealloc->end = split - 1;
         prealloc->state = orig->state;
@@ -542,8 +571,8 @@ hit_next:
                 if (err)
                         goto out;
                 if (state->end <= end) {
-                        set |= clear_state_bit(tree, state, bits,
-                                        wake, delete);
+                        set |= clear_state_bit(tree, state, bits, wake,
+                                               delete);
                         if (last_end == (u64)-1)
                                 goto out;
                         start = last_end + 1;
@@ -561,12 +590,11 @@ hit_next:
                         prealloc = alloc_extent_state(GFP_ATOMIC);
                 err = split_state(tree, state, prealloc, end + 1);
                 BUG_ON(err == -EEXIST);
-
                 if (wake)
                         wake_up(&state->wq);
 
-                set |= clear_state_bit(tree, prealloc, bits,
-                                       wake, delete);
+                set |= clear_state_bit(tree, prealloc, bits, wake, delete);
+
                 prealloc = NULL;
                 goto out;
         }
@@ -667,16 +695,23 @@ out:
         return 0;
 }
 
-static void set_state_bits(struct extent_io_tree *tree,
+static int set_state_bits(struct extent_io_tree *tree,
                            struct extent_state *state,
                            int bits)
 {
+        int ret;
+
+        ret = set_state_cb(tree, state, bits);
+        if (ret)
+                return ret;
+
         if ((bits & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) {
                 u64 range = state->end - state->start + 1;
                 tree->dirty_bytes += range;
         }
-        set_state_cb(tree, state, bits);
         state->state |= bits;
+
+        return 0;
 }
 
 static void cache_state(struct extent_state *state,
@@ -758,7 +793,10 @@ hit_next:
                         goto out;
                 }
 
-                set_state_bits(tree, state, bits);
+                err = set_state_bits(tree, state, bits);
+                if (err)
+                        goto out;
+
                 cache_state(state, cached_state);
                 merge_state(tree, state);
                 if (last_end == (u64)-1)
@@ -805,7 +843,9 @@ hit_next:
                 if (err)
                         goto out;
                 if (state->end <= end) {
-                        set_state_bits(tree, state, bits);
+                        err = set_state_bits(tree, state, bits);
+                        if (err)
+                                goto out;
                         cache_state(state, cached_state);
                         merge_state(tree, state);
                         if (last_end == (u64)-1)
@@ -829,11 +869,13 @@ hit_next:
                         this_end = last_start - 1;
                 err = insert_state(tree, prealloc, start, this_end,
                                    bits);
-                cache_state(prealloc, cached_state);
-                prealloc = NULL;
                 BUG_ON(err == -EEXIST);
-                if (err)
+                if (err) {
+                        prealloc = NULL;
                         goto out;
+                }
+                cache_state(prealloc, cached_state);
+                prealloc = NULL;
                 start = this_end + 1;
                 goto search_again;
         }
@@ -852,7 +894,11 @@ hit_next:
                 err = split_state(tree, state, prealloc, end + 1);
                 BUG_ON(err == -EEXIST);
 
-                set_state_bits(tree, prealloc, bits);
+                err = set_state_bits(tree, prealloc, bits);
+                if (err) {
+                        prealloc = NULL;
+                        goto out;
+                }
                 cache_state(prealloc, cached_state);
                 merge_state(tree, prealloc);
                 prealloc = NULL;
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 14ed16fd862d..4794ec891fed 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -60,8 +60,13 @@ struct extent_io_ops {
                                       struct extent_state *state, int uptodate);
         int (*set_bit_hook)(struct inode *inode, u64 start, u64 end,
                             unsigned long old, unsigned long bits);
-        int (*clear_bit_hook)(struct inode *inode, u64 start, u64 end,
-                            unsigned long old, unsigned long bits);
+        int (*clear_bit_hook)(struct inode *inode, struct extent_state *state,
+                              unsigned long bits);
+        int (*merge_extent_hook)(struct inode *inode,
+                                 struct extent_state *new,
+                                 struct extent_state *other);
+        int (*split_extent_hook)(struct inode *inode,
+                                 struct extent_state *orig, u64 split);
         int (*write_cache_pages_lock_hook)(struct page *page);
 };
 
@@ -79,10 +84,14 @@ struct extent_state {
         u64 start;
         u64 end; /* inclusive */
         struct rb_node rb_node;
+
+        /* ADD NEW ELEMENTS AFTER THIS */
         struct extent_io_tree *tree;
         wait_queue_head_t wq;
         atomic_t refs;
         unsigned long state;
+        u64 split_start;
+        u64 split_end;
 
         /* for use by the FS */
         u64 private;
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 571ad3c13b47..1be96ba6f6bb 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -123,7 +123,10 @@ static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
 
         end_of_last_block = start_pos + num_bytes - 1;
-        btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
+        err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
+        if (err)
+                return err;
+
         for (i = 0; i < num_pages; i++) {
                 struct page *p = pages[i];
                 SetPageUptodate(p);
@@ -927,6 +930,11 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
         err = file_remove_suid(file);
         if (err)
                 goto out_nolock;
+
+        err = btrfs_reserve_metadata_for_delalloc(root, inode, 1);
+        if (err)
+                goto out_nolock;
+
         file_update_time(file);
 
         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
@@ -1028,6 +1036,7 @@ out:
         mutex_unlock(&inode->i_mutex);
         if (ret)
                 err = ret;
+        btrfs_unreserve_metadata_for_delalloc(root, inode, 1);
 
 out_nolock:
         kfree(pages);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 01c5f8b5a34e..3cc5677f5440 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1159,6 +1159,83 @@ static int run_delalloc_range(struct inode *inode, struct page *locked_page,
         return ret;
 }
 
+static int btrfs_split_extent_hook(struct inode *inode,
+                                    struct extent_state *orig, u64 split)
+{
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+        u64 size;
+
+        if (!(orig->state & EXTENT_DELALLOC))
+                return 0;
+
+        size = orig->end - orig->start + 1;
+        if (size > root->fs_info->max_extent) {
+                u64 num_extents;
+                u64 new_size;
+
+                new_size = orig->end - split + 1;
+                num_extents = div64_u64(size + root->fs_info->max_extent - 1,
+                                        root->fs_info->max_extent);
+
+                /*
+                 * if we break a large extent up then leave delalloc_extents be,
+                 * since we've already accounted for the large extent.
+                 */
+                if (div64_u64(new_size + root->fs_info->max_extent - 1,
+                              root->fs_info->max_extent) < num_extents)
+                        return 0;
+        }
+
+        BTRFS_I(inode)->delalloc_extents++;
+
+        return 0;
+}
+
+/*
+ * extent_io.c merge_extent_hook, used to track merged delayed allocation
+ * extents so we can keep track of new extents that are just merged onto old
+ * extents, such as when we are doing sequential writes, so we can properly
+ * account for the metadata space we'll need.
+ */
+static int btrfs_merge_extent_hook(struct inode *inode,
+                                   struct extent_state *new,
+                                   struct extent_state *other)
+{
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+        u64 new_size, old_size;
+        u64 num_extents;
+
+        /* not delalloc, ignore it */
+        if (!(other->state & EXTENT_DELALLOC))
+                return 0;
+
+        old_size = other->end - other->start + 1;
+        if (new->start < other->start)
+                new_size = other->end - new->start + 1;
+        else
+                new_size = new->end - other->start + 1;
+
+        /* we're not bigger than the max, unreserve the space and go */
+        if (new_size <= root->fs_info->max_extent) {
+                BTRFS_I(inode)->delalloc_extents--;
+                return 0;
+        }
+
+        /*
+         * If we grew by another max_extent, just return, we want to keep that
+         * reserved amount.
+         */
+        num_extents = div64_u64(old_size + root->fs_info->max_extent - 1,
+                                root->fs_info->max_extent);
+        if (div64_u64(new_size + root->fs_info->max_extent - 1,
+                      root->fs_info->max_extent) > num_extents)
+                return 0;
+
+        BTRFS_I(inode)->delalloc_extents--;
+
+        return 0;
+}
+
 /*
  * extent_io.c set_bit_hook, used to track delayed allocation
  * bytes in this file, and to maintain the list of inodes that
@@ -1167,6 +1244,7 @@ static int run_delalloc_range(struct inode *inode, struct page *locked_page,
 static int btrfs_set_bit_hook(struct inode *inode, u64 start, u64 end,
                        unsigned long old, unsigned long bits)
 {
+
         /*
          * set_bit and clear bit hooks normally require _irqsave/restore
          * but in this case, we are only testeing for the DELALLOC
@@ -1174,6 +1252,8 @@ static int btrfs_set_bit_hook(struct inode *inode, u64 start, u64 end,
          */
         if (!(old & EXTENT_DELALLOC) && (bits & EXTENT_DELALLOC)) {
                 struct btrfs_root *root = BTRFS_I(inode)->root;
+
+                BTRFS_I(inode)->delalloc_extents++;
                 btrfs_delalloc_reserve_space(root, inode, end - start + 1);
                 spin_lock(&root->fs_info->delalloc_lock);
                 BTRFS_I(inode)->delalloc_bytes += end - start + 1;
@@ -1190,22 +1270,27 @@ static int btrfs_set_bit_hook(struct inode *inode, u64 start, u64 end,
 /*
  * extent_io.c clear_bit_hook, see set_bit_hook for why
  */
-static int btrfs_clear_bit_hook(struct inode *inode, u64 start, u64 end,
-                         unsigned long old, unsigned long bits)
+static int btrfs_clear_bit_hook(struct inode *inode,
+                                struct extent_state *state, unsigned long bits)
 {
         /*
          * set_bit and clear bit hooks normally require _irqsave/restore
          * but in this case, we are only testeing for the DELALLOC
          * bit, which is only set or cleared with irqs on
          */
-        if ((old & EXTENT_DELALLOC) && (bits & EXTENT_DELALLOC)) {
+        if ((state->state & EXTENT_DELALLOC) && (bits & EXTENT_DELALLOC)) {
                 struct btrfs_root *root = BTRFS_I(inode)->root;
 
+                BTRFS_I(inode)->delalloc_extents--;
+                btrfs_unreserve_metadata_for_delalloc(root, inode, 1);
+
                 spin_lock(&root->fs_info->delalloc_lock);
-                if (end - start + 1 > root->fs_info->delalloc_bytes) {
+                if (state->end - state->start + 1 >
+                    root->fs_info->delalloc_bytes) {
                         printk(KERN_INFO "btrfs warning: delalloc account "
                                "%llu %llu\n",
-                               (unsigned long long)end - start + 1,
+                               (unsigned long long)
+                               state->end - state->start + 1,
                                (unsigned long long)
                                root->fs_info->delalloc_bytes);
                         btrfs_delalloc_free_space(root, inode, (u64)-1);
@@ -1213,9 +1298,12 @@ static int btrfs_clear_bit_hook(struct inode *inode, u64 start, u64 end,
                         BTRFS_I(inode)->delalloc_bytes = 0;
                 } else {
                         btrfs_delalloc_free_space(root, inode,
-                                                  end - start + 1);
-                        root->fs_info->delalloc_bytes -= end - start + 1;
-                        BTRFS_I(inode)->delalloc_bytes -= end - start + 1;
+                                                  state->end -
+                                                  state->start + 1);
+                        root->fs_info->delalloc_bytes -= state->end -
+                                state->start + 1;
+                        BTRFS_I(inode)->delalloc_bytes -= state->end -
+                                state->start + 1;
                 }
                 if (BTRFS_I(inode)->delalloc_bytes == 0 &&
                     !list_empty(&BTRFS_I(inode)->delalloc_inodes)) {
@@ -2950,7 +3038,12 @@ again:
                 goto again;
         }
 
-        btrfs_set_extent_delalloc(inode, page_start, page_end);
+        ret = btrfs_set_extent_delalloc(inode, page_start, page_end);
+        if (ret) {
+                unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
+                goto out_unlock;
+        }
+
         ret = 0;
         if (offset != PAGE_CACHE_SIZE) {
                 kaddr = kmap(page);
@@ -2981,15 +3074,11 @@ int btrfs_cont_expand(struct inode *inode, loff_t size)
         u64 last_byte;
         u64 cur_offset;
         u64 hole_size;
-        int err;
+        int err = 0;
 
         if (size <= hole_start)
                 return 0;
 
-        err = btrfs_check_metadata_free_space(root);
-        if (err)
-                return err;
-
         btrfs_truncate_page(inode->i_mapping, inode->i_size);
 
         while (1) {
@@ -3024,12 +3113,18 @@ int btrfs_cont_expand(struct inode *inode, loff_t size)
                                                  cur_offset, &hint_byte, 1);
                         if (err)
                                 break;
+
+                        err = btrfs_reserve_metadata_space(root, 1);
+                        if (err)
+                                break;
+
                         err = btrfs_insert_file_extent(trans, root,
                                         inode->i_ino, cur_offset, 0,
                                         0, hole_size, 0, hole_size,
                                         0, 0, 0);
                         btrfs_drop_extent_cache(inode, hole_start,
                                         last_byte - 1, 0);
+                        btrfs_unreserve_metadata_space(root, 1);
                 }
                 free_extent_map(em);
                 cur_offset = last_byte;
@@ -3990,11 +4085,18 @@ static int btrfs_mknod(struct inode *dir, struct dentry *dentry,
         if (!new_valid_dev(rdev))
                 return -EINVAL;
 
-        err = btrfs_check_metadata_free_space(root);
+        /*
+         * 2 for inode item and ref
+         * 2 for dir items
+         * 1 for xattr if selinux is on
+         */
+        err = btrfs_reserve_metadata_space(root, 5);
         if (err)
-                goto fail;
+                return err;
 
         trans = btrfs_start_transaction(root, 1);
+        if (!trans)
+                goto fail;
         btrfs_set_trans_block_group(trans, dir);
 
         err = btrfs_find_free_objectid(trans, root, dir->i_ino, &objectid);
@@ -4032,6 +4134,7 @@ out_unlock:
         nr = trans->blocks_used;
         btrfs_end_transaction_throttle(trans, root);
 fail:
+        btrfs_unreserve_metadata_space(root, 5);
         if (drop_inode) {
                 inode_dec_link_count(inode);
                 iput(inode);
@@ -4052,10 +4155,18 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
         u64 objectid;
         u64 index = 0;
 
-        err = btrfs_check_metadata_free_space(root);
+        /*
+         * 2 for inode item and ref
+         * 2 for dir items
+         * 1 for xattr if selinux is on
+         */
+        err = btrfs_reserve_metadata_space(root, 5);
         if (err)
-                goto fail;
+                return err;
+
         trans = btrfs_start_transaction(root, 1);
+        if (!trans)
+                goto fail;
         btrfs_set_trans_block_group(trans, dir);
 
         err = btrfs_find_free_objectid(trans, root, dir->i_ino, &objectid);
@@ -4096,6 +4207,7 @@ out_unlock:
         nr = trans->blocks_used;
         btrfs_end_transaction_throttle(trans, root);
 fail:
+        btrfs_unreserve_metadata_space(root, 5);
         if (drop_inode) {
                 inode_dec_link_count(inode);
                 iput(inode);
@@ -4118,10 +4230,16 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
         if (inode->i_nlink == 0)
                 return -ENOENT;
 
-        btrfs_inc_nlink(inode);
-        err = btrfs_check_metadata_free_space(root);
+        /*
+         * 1 item for inode ref
+         * 2 items for dir items
+         */
+        err = btrfs_reserve_metadata_space(root, 3);
         if (err)
-                goto fail;
+                return err;
+
+        btrfs_inc_nlink(inode);
+
         err = btrfs_set_inode_index(dir, &index);
         if (err)
                 goto fail;
@@ -4145,6 +4263,7 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
         nr = trans->blocks_used;
         btrfs_end_transaction_throttle(trans, root);
 fail:
+        btrfs_unreserve_metadata_space(root, 3);
         if (drop_inode) {
                 inode_dec_link_count(inode);
                 iput(inode);
@@ -4164,17 +4283,21 @@ static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
         u64 index = 0;
         unsigned long nr = 1;
 
-        err = btrfs_check_metadata_free_space(root);
+        /*
+         * 2 items for inode and ref
+         * 2 items for dir items
+         * 1 for xattr if selinux is on
+         */
+        err = btrfs_reserve_metadata_space(root, 5);
         if (err)
-                goto out_unlock;
+                return err;
 
         trans = btrfs_start_transaction(root, 1);
-        btrfs_set_trans_block_group(trans, dir);
-
-        if (IS_ERR(trans)) {
-                err = PTR_ERR(trans);
+        if (!trans) {
+                err = -ENOMEM;
                 goto out_unlock;
         }
+        btrfs_set_trans_block_group(trans, dir);
 
         err = btrfs_find_free_objectid(trans, root, dir->i_ino, &objectid);
         if (err) {
@@ -4223,6 +4346,7 @@ out_fail:
         btrfs_end_transaction_throttle(trans, root);
 
 out_unlock:
+        btrfs_unreserve_metadata_space(root, 5);
         if (drop_on_err)
                 iput(inode);
         btrfs_btree_balance_dirty(root, nr);
@@ -4747,6 +4871,13 @@ int btrfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
                 goto out;
         }
 
+        ret = btrfs_reserve_metadata_for_delalloc(root, inode, 1);
+        if (ret) {
+                btrfs_free_reserved_data_space(root, inode, PAGE_CACHE_SIZE);
+                ret = VM_FAULT_SIGBUS;
+                goto out;
+        }
+
         ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */
 again:
         lock_page(page);
@@ -4778,7 +4909,12 @@ again:
                 goto again;
         }
 
-        btrfs_set_extent_delalloc(inode, page_start, page_end);
+        ret = btrfs_set_extent_delalloc(inode, page_start, page_end);
+        if (ret) {
+                unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
+                ret = VM_FAULT_SIGBUS;
+                goto out_unlock;
+        }
         ret = 0;
 
         /* page is wholly or partially inside EOF */
@@ -4801,6 +4937,7 @@ again:
         unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
 
 out_unlock:
+        btrfs_unreserve_metadata_for_delalloc(root, inode, 1);
         if (!ret)
                 return VM_FAULT_LOCKED;
         unlock_page(page);
@@ -4917,6 +5054,8 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
                 return NULL;
         ei->last_trans = 0;
         ei->logged_trans = 0;
+        ei->delalloc_extents = 0;
+        ei->delalloc_reserved_extents = 0;
         btrfs_ordered_inode_tree_init(&ei->ordered_tree);
         INIT_LIST_HEAD(&ei->i_orphan);
         INIT_LIST_HEAD(&ei->ordered_operations);
@@ -5070,7 +5209,12 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
             new_inode->i_size > BTRFS_EMPTY_DIR_SIZE)
                 return -ENOTEMPTY;
 
-        ret = btrfs_check_metadata_free_space(root);
+        /*
+         * 2 items for dir items
+         * 1 item for orphan entry
+         * 1 item for ref
+         */
+        ret = btrfs_reserve_metadata_space(root, 4);
         if (ret)
                 return ret;
 
@@ -5185,6 +5329,8 @@ out_fail:
 
         if (old_inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
                 up_read(&root->fs_info->subvol_sem);
+
+        btrfs_unreserve_metadata_space(root, 4);
         return ret;
 }
 
@@ -5256,11 +5402,18 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
         if (name_len > BTRFS_MAX_INLINE_DATA_SIZE(root))
                 return -ENAMETOOLONG;
 
-        err = btrfs_check_metadata_free_space(root);
+        /*
+         * 2 items for inode item and ref
+         * 2 items for dir items
+         * 1 item for xattr if selinux is on
+         */
+        err = btrfs_reserve_metadata_space(root, 5);
         if (err)
-                goto out_fail;
+                return err;
 
         trans = btrfs_start_transaction(root, 1);
+        if (!trans)
+                goto out_fail;
         btrfs_set_trans_block_group(trans, dir);
 
         err = btrfs_find_free_objectid(trans, root, dir->i_ino, &objectid);
@@ -5341,6 +5494,7 @@ out_unlock:
         nr = trans->blocks_used;
         btrfs_end_transaction_throttle(trans, root);
 out_fail:
+        btrfs_unreserve_metadata_space(root, 5);
         if (drop_inode) {
                 inode_dec_link_count(inode);
                 iput(inode);
@@ -5362,6 +5516,11 @@ static int prealloc_file_range(struct btrfs_trans_handle *trans,
 
         while (num_bytes > 0) {
                 alloc_size = min(num_bytes, root->fs_info->max_extent);
+
+                ret = btrfs_reserve_metadata_space(root, 1);
+                if (ret)
+                        goto out;
+
                 ret = btrfs_reserve_extent(trans, root, alloc_size,
                                            root->sectorsize, 0, alloc_hint,
                                            (u64)-1, &ins, 1);
@@ -5381,6 +5540,7 @@ static int prealloc_file_range(struct btrfs_trans_handle *trans,
                 num_bytes -= ins.offset;
                 cur_offset += ins.offset;
                 alloc_hint = ins.objectid + ins.offset;
+                btrfs_unreserve_metadata_space(root, 1);
         }
 out:
         if (cur_offset > start) {
@@ -5566,6 +5726,8 @@ static struct extent_io_ops btrfs_extent_io_ops = {
         .readpage_io_failed_hook = btrfs_io_failed_hook,
         .set_bit_hook = btrfs_set_bit_hook,
         .clear_bit_hook = btrfs_clear_bit_hook,
+        .merge_extent_hook = btrfs_merge_extent_hook,
+        .split_extent_hook = btrfs_split_extent_hook,
 };
 
 /*
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a8577a7f26ab..4de7ef6f8603 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -239,7 +239,13 @@ static noinline int create_subvol(struct btrfs_root *root,
         u64 index = 0;
         unsigned long nr = 1;
 
-        ret = btrfs_check_metadata_free_space(root);
+        /*
+         * 1 - inode item
+         * 2 - refs
+         * 1 - root item
+         * 2 - dir items
+         */
+        ret = btrfs_reserve_metadata_space(root, 6);
         if (ret)
                 return ret;
 
@@ -340,6 +346,9 @@ fail:
         err = btrfs_commit_transaction(trans, root);
         if (err && !ret)
                 ret = err;
+
+        btrfs_unreserve_metadata_space(root, 6);
+        btrfs_btree_balance_dirty(root, nr);
         return ret;
 }
 
@@ -355,19 +364,27 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
         if (!root->ref_cows)
                 return -EINVAL;
 
-        ret = btrfs_check_metadata_free_space(root);
+        /*
+         * 1 - inode item
+         * 2 - refs
+         * 1 - root item
+         * 2 - dir items
+         */
+        ret = btrfs_reserve_metadata_space(root, 6);
         if (ret)
                 goto fail_unlock;
 
         pending_snapshot = kzalloc(sizeof(*pending_snapshot), GFP_NOFS);
         if (!pending_snapshot) {
                 ret = -ENOMEM;
+                btrfs_unreserve_metadata_space(root, 6);
                 goto fail_unlock;
         }
         pending_snapshot->name = kmalloc(namelen + 1, GFP_NOFS);
         if (!pending_snapshot->name) {
                 ret = -ENOMEM;
                 kfree(pending_snapshot);
+                btrfs_unreserve_metadata_space(root, 6);
                 goto fail_unlock;
         }
         memcpy(pending_snapshot->name, name, namelen);
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 88f866f85e7a..0b8f36d4400a 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -186,6 +186,9 @@ static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
         h->alloc_exclude_start = 0;
         h->delayed_ref_updates = 0;
 
+        if (!current->journal_info)
+                current->journal_info = h;
+
         root->fs_info->running_transaction->use_count++;
         record_root_in_trans(h, root);
         mutex_unlock(&root->fs_info->trans_mutex);
@@ -317,6 +320,9 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
                 wake_up(&cur_trans->writer_wait);
         put_transaction(cur_trans);
         mutex_unlock(&info->trans_mutex);
+
+        if (current->journal_info == trans)
+                current->journal_info = NULL;
         memset(trans, 0, sizeof(*trans));
         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 
@@ -743,6 +749,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         memcpy(&pending->root_key, &key, sizeof(key));
 fail:
         kfree(new_root_item);
+        btrfs_unreserve_metadata_space(root, 6);
         return ret;
 }
 
@@ -1059,6 +1066,9 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 
         mutex_unlock(&root->fs_info->trans_mutex);
 
+        if (current->journal_info == trans)
+                current->journal_info = NULL;
+
         kmem_cache_free(btrfs_trans_handle_cachep, trans);
         return ret;
 }