1 files changed, 494 insertions, 254 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 66e4c66cc63b..51dcec86757f 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -27,15 +27,15 @@
 #include "transaction.h"
 #include "locking.h"
 #include "tree-log.h"
+#include "inode-map.h"
 
 #define BTRFS_ROOT_TRANS_TAG 0
 
 static noinline void put_transaction(struct btrfs_transaction *transaction)
 {
-        WARN_ON(transaction->use_count == 0);
-        transaction->use_count--;
-        if (transaction->use_count == 0) {
-                list_del_init(&transaction->list);
+        WARN_ON(atomic_read(&transaction->use_count) == 0);
+        if (atomic_dec_and_test(&transaction->use_count)) {
+                BUG_ON(!list_empty(&transaction->list));
                 memset(transaction, 0, sizeof(*transaction));
                 kmem_cache_free(btrfs_transaction_cachep, transaction);
         }
@@ -50,46 +50,72 @@ static noinline void switch_commit_root(struct btrfs_root *root)
 /*
  * either allocate a new transaction or hop into the existing one
  */
-static noinline int join_transaction(struct btrfs_root *root)
+static noinline int join_transaction(struct btrfs_root *root, int nofail)
 {
         struct btrfs_transaction *cur_trans;
+
+        spin_lock(&root->fs_info->trans_lock);
+        if (root->fs_info->trans_no_join) {
+                if (!nofail) {
+                        spin_unlock(&root->fs_info->trans_lock);
+                        return -EBUSY;
+                }
+        }
+
         cur_trans = root->fs_info->running_transaction;
-        if (!cur_trans) {
-                cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
-                                             GFP_NOFS);
-                BUG_ON(!cur_trans);
-                root->fs_info->generation++;
-                cur_trans->num_writers = 1;
-                cur_trans->num_joined = 0;
-                cur_trans->transid = root->fs_info->generation;
-                init_waitqueue_head(&cur_trans->writer_wait);
-                init_waitqueue_head(&cur_trans->commit_wait);
-                cur_trans->in_commit = 0;
-                cur_trans->blocked = 0;
-                cur_trans->use_count = 1;
-                cur_trans->commit_done = 0;
-                cur_trans->start_time = get_seconds();
-
-                cur_trans->delayed_refs.root = RB_ROOT;
-                cur_trans->delayed_refs.num_entries = 0;
-                cur_trans->delayed_refs.num_heads_ready = 0;
-                cur_trans->delayed_refs.num_heads = 0;
-                cur_trans->delayed_refs.flushing = 0;
-                cur_trans->delayed_refs.run_delayed_start = 0;
-                spin_lock_init(&cur_trans->delayed_refs.lock);
-
-                INIT_LIST_HEAD(&cur_trans->pending_snapshots);
-                list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
-                extent_io_tree_init(&cur_trans->dirty_pages,
-                                     root->fs_info->btree_inode->i_mapping,
-                                     GFP_NOFS);
-                spin_lock(&root->fs_info->new_trans_lock);
-                root->fs_info->running_transaction = cur_trans;
-                spin_unlock(&root->fs_info->new_trans_lock);
-        } else {
-                cur_trans->num_writers++;
+        if (cur_trans) {
+                atomic_inc(&cur_trans->use_count);
+                atomic_inc(&cur_trans->num_writers);
                 cur_trans->num_joined++;
+                spin_unlock(&root->fs_info->trans_lock);
+                return 0;
         }
+        spin_unlock(&root->fs_info->trans_lock);
+
+        cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
+        if (!cur_trans)
+                return -ENOMEM;
+        spin_lock(&root->fs_info->trans_lock);
+        if (root->fs_info->running_transaction) {
+                kmem_cache_free(btrfs_transaction_cachep, cur_trans);
+                cur_trans = root->fs_info->running_transaction;
+                atomic_inc(&cur_trans->use_count);
+                atomic_inc(&cur_trans->num_writers);
+                cur_trans->num_joined++;
+                spin_unlock(&root->fs_info->trans_lock);
+                return 0;
+        }
+        atomic_set(&cur_trans->num_writers, 1);
+        cur_trans->num_joined = 0;
+        init_waitqueue_head(&cur_trans->writer_wait);
+        init_waitqueue_head(&cur_trans->commit_wait);
+        cur_trans->in_commit = 0;
+        cur_trans->blocked = 0;
+        /*
+         * One for this trans handle, one so it will live on until we
+         * commit the transaction.
+         */
+        atomic_set(&cur_trans->use_count, 2);
+        cur_trans->commit_done = 0;
+        cur_trans->start_time = get_seconds();
+
+        cur_trans->delayed_refs.root = RB_ROOT;
+        cur_trans->delayed_refs.num_entries = 0;
+        cur_trans->delayed_refs.num_heads_ready = 0;
+        cur_trans->delayed_refs.num_heads = 0;
+        cur_trans->delayed_refs.flushing = 0;
+        cur_trans->delayed_refs.run_delayed_start = 0;
+        spin_lock_init(&cur_trans->commit_lock);
+        spin_lock_init(&cur_trans->delayed_refs.lock);
+
+        INIT_LIST_HEAD(&cur_trans->pending_snapshots);
+        list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
+        extent_io_tree_init(&cur_trans->dirty_pages,
+                             root->fs_info->btree_inode->i_mapping);
+        root->fs_info->generation++;
+        cur_trans->transid = root->fs_info->generation;
+        root->fs_info->running_transaction = cur_trans;
+        spin_unlock(&root->fs_info->trans_lock);
 
         return 0;
 }
@@ -100,36 +126,82 @@ static noinline int join_transaction(struct btrfs_root *root)
  * to make sure the old root from before we joined the transaction is deleted
  * when the transaction commits
  */
-static noinline int record_root_in_trans(struct btrfs_trans_handle *trans,
-                                         struct btrfs_root *root)
+static int record_root_in_trans(struct btrfs_trans_handle *trans,
+                               struct btrfs_root *root)
 {
         if (root->ref_cows && root->last_trans < trans->transid) {
                 WARN_ON(root == root->fs_info->extent_root);
                 WARN_ON(root->commit_root != root->node);
 
+                /*
+                 * see below for in_trans_setup usage rules
+                 * we have the reloc mutex held now, so there
+                 * is only one writer in this function
+                 */
+                root->in_trans_setup = 1;
+
+                /* make sure readers find in_trans_setup before
+                 * they find our root->last_trans update
+                 */
+                smp_wmb();
+
+                spin_lock(&root->fs_info->fs_roots_radix_lock);
+                if (root->last_trans == trans->transid) {
+                        spin_unlock(&root->fs_info->fs_roots_radix_lock);
+                        return 0;
+                }
                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
                            (unsigned long)root->root_key.objectid,
                            BTRFS_ROOT_TRANS_TAG);
+                spin_unlock(&root->fs_info->fs_roots_radix_lock);
                 root->last_trans = trans->transid;
+
+                /* this is pretty tricky.  We don't want to
+                 * take the relocation lock in btrfs_record_root_in_trans
+                 * unless we're really doing the first setup for this root in
+                 * this transaction.
+                 *
+                 * Normally we'd use root->last_trans as a flag to decide
+                 * if we want to take the expensive mutex.
+                 *
+                 * But, we have to set root->last_trans before we
+                 * init the relocation root, otherwise, we trip over warnings
+                 * in ctree.c.  The solution used here is to flag ourselves
+                 * with root->in_trans_setup.  When this is 1, we're still
+                 * fixing up the reloc trees and everyone must wait.
+                 *
+                 * When this is zero, they can trust root->last_trans and fly
+                 * through btrfs_record_root_in_trans without having to take the
+                 * lock.  smp_wmb() makes sure that all the writes above are
+                 * done before we pop in the zero below
+                 */
                 btrfs_init_reloc_root(trans, root);
+                smp_wmb();
+                root->in_trans_setup = 0;
         }
         return 0;
 }
 
+
 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
                                struct btrfs_root *root)
 {
         if (!root->ref_cows)
                 return 0;
 
-        mutex_lock(&root->fs_info->trans_mutex);
-        if (root->last_trans == trans->transid) {
-                mutex_unlock(&root->fs_info->trans_mutex);
+        /*
+         * see record_root_in_trans for comments about in_trans_setup usage
+         * and barriers
+         */
+        smp_rmb();
+        if (root->last_trans == trans->transid &&
+            !root->in_trans_setup)
                 return 0;
-        }
 
+        mutex_lock(&root->fs_info->reloc_mutex);
         record_root_in_trans(trans, root);
-        mutex_unlock(&root->fs_info->trans_mutex);
+        mutex_unlock(&root->fs_info->reloc_mutex);
+
         return 0;
 }
 
@@ -141,21 +213,23 @@ static void wait_current_trans(struct btrfs_root *root)
 {
         struct btrfs_transaction *cur_trans;
 
+        spin_lock(&root->fs_info->trans_lock);
         cur_trans = root->fs_info->running_transaction;
         if (cur_trans && cur_trans->blocked) {
                 DEFINE_WAIT(wait);
-                cur_trans->use_count++;
+                atomic_inc(&cur_trans->use_count);
+                spin_unlock(&root->fs_info->trans_lock);
                 while (1) {
                         prepare_to_wait(&root->fs_info->transaction_wait, &wait,
                                         TASK_UNINTERRUPTIBLE);
                         if (!cur_trans->blocked)
                                 break;
-                        mutex_unlock(&root->fs_info->trans_mutex);
                         schedule();
-                        mutex_lock(&root->fs_info->trans_mutex);
                 }
                 finish_wait(&root->fs_info->transaction_wait, &wait);
                 put_transaction(cur_trans);
+        } else {
+                spin_unlock(&root->fs_info->trans_lock);
         }
 }
 
@@ -163,14 +237,21 @@ enum btrfs_trans_type {
         TRANS_START,
         TRANS_JOIN,
         TRANS_USERSPACE,
+        TRANS_JOIN_NOLOCK,
 };
 
 static int may_wait_transaction(struct btrfs_root *root, int type)
 {
-        if (!root->fs_info->log_root_recovering &&
-            ((type == TRANS_START && !root->fs_info->open_ioctl_trans) ||
-             type == TRANS_USERSPACE))
+        if (root->fs_info->log_root_recovering)
+                return 0;
+
+        if (type == TRANS_USERSPACE)
                 return 1;
+
+        if (type == TRANS_START &&
+            !atomic_read(&root->fs_info->open_ioctl_trans))
+                return 1;
+
         return 0;
 }
 
@@ -181,29 +262,47 @@ static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
         struct btrfs_transaction *cur_trans;
         int retries = 0;
         int ret;
+
+        if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
+                return ERR_PTR(-EROFS);
+
+        if (current->journal_info) {
+                WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
+                h = current->journal_info;
+                h->use_count++;
+                h->orig_rsv = h->block_rsv;
+                h->block_rsv = NULL;
+                goto got_it;
+        }
 again:
         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
         if (!h)
                 return ERR_PTR(-ENOMEM);
 
-        mutex_lock(&root->fs_info->trans_mutex);
         if (may_wait_transaction(root, type))
                 wait_current_trans(root);
 
-        ret = join_transaction(root);
-        BUG_ON(ret);
+        do {
+                ret = join_transaction(root, type == TRANS_JOIN_NOLOCK);
+                if (ret == -EBUSY)
+                        wait_current_trans(root);
+        } while (ret == -EBUSY);
+
+        if (ret < 0) {
+                kmem_cache_free(btrfs_trans_handle_cachep, h);
+                return ERR_PTR(ret);
+        }
 
         cur_trans = root->fs_info->running_transaction;
-        cur_trans->use_count++;
-        mutex_unlock(&root->fs_info->trans_mutex);
 
         h->transid = cur_trans->transid;
         h->transaction = cur_trans;
         h->blocks_used = 0;
-        h->block_group = 0;
         h->bytes_reserved = 0;
         h->delayed_ref_updates = 0;
+        h->use_count = 1;
         h->block_rsv = NULL;
+        h->orig_rsv = NULL;
 
         smp_mb();
         if (cur_trans->blocked && may_wait_transaction(root, type)) {
@@ -212,21 +311,27 @@ again:
         }
 
         if (num_items > 0) {
-                ret = btrfs_trans_reserve_metadata(h, root, num_items,
-                                                   &retries);
-                if (ret == -EAGAIN) {
+                ret = btrfs_trans_reserve_metadata(h, root, num_items);
+                if (ret == -EAGAIN && !retries) {
+                        retries++;
                         btrfs_commit_transaction(h, root);
                         goto again;
+                } else if (ret == -EAGAIN) {
+                        /*
+                         * We have already retried and got EAGAIN, so really we
+                         * don't have space, so set ret to -ENOSPC.
+                         */
+                        ret = -ENOSPC;
                 }
+
                 if (ret < 0) {
                         btrfs_end_transaction(h, root);
                         return ERR_PTR(ret);
                 }
         }
 
-        mutex_lock(&root->fs_info->trans_mutex);
-        record_root_in_trans(h, root);
-        mutex_unlock(&root->fs_info->trans_mutex);
+got_it:
+        btrfs_record_root_in_trans(h, root);
 
         if (!current->journal_info && type != TRANS_USERSPACE)
                 current->journal_info = h;
@@ -238,16 +343,19 @@ struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 {
         return start_transaction(root, num_items, TRANS_START);
 }
-struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
-                                                   int num_blocks)
+struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 {
         return start_transaction(root, 0, TRANS_JOIN);
 }
 
-struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
-                                                         int num_blocks)
+struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
+{
+        return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
+}
+
+struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 {
-        return start_transaction(r, 0, TRANS_USERSPACE);
+        return start_transaction(root, 0, TRANS_USERSPACE);
 }
 
 /* wait for a transaction commit to be fully complete */
@@ -255,70 +363,72 @@ static noinline int wait_for_commit(struct btrfs_root *root,
                                     struct btrfs_transaction *commit)
 {
         DEFINE_WAIT(wait);
-        mutex_lock(&root->fs_info->trans_mutex);
         while (!commit->commit_done) {
                 prepare_to_wait(&commit->commit_wait, &wait,
                                 TASK_UNINTERRUPTIBLE);
                 if (commit->commit_done)
                         break;
-                mutex_unlock(&root->fs_info->trans_mutex);
                 schedule();
-                mutex_lock(&root->fs_info->trans_mutex);
         }
-        mutex_unlock(&root->fs_info->trans_mutex);
         finish_wait(&commit->commit_wait, &wait);
         return 0;
 }
 
-#if 0
-/*
- * rate limit against the drop_snapshot code.  This helps to slow down new
- * operations if the drop_snapshot code isn't able to keep up.
- */
-static void throttle_on_drops(struct btrfs_root *root)
+int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 {
-        struct btrfs_fs_info *info = root->fs_info;
-        int harder_count = 0;
+        struct btrfs_transaction *cur_trans = NULL, *t;
+        int ret;
 
-harder:
-        if (atomic_read(&info->throttles)) {
-                DEFINE_WAIT(wait);
-                int thr;
-                thr = atomic_read(&info->throttle_gen);
-
-                do {
-                        prepare_to_wait(&info->transaction_throttle,
-                                        &wait, TASK_UNINTERRUPTIBLE);
-                        if (!atomic_read(&info->throttles)) {
-                                finish_wait(&info->transaction_throttle, &wait);
+        ret = 0;
+        if (transid) {
+                if (transid <= root->fs_info->last_trans_committed)
+                        goto out;
+
+                /* find specified transaction */
+                spin_lock(&root->fs_info->trans_lock);
+                list_for_each_entry(t, &root->fs_info->trans_list, list) {
+                        if (t->transid == transid) {
+                                cur_trans = t;
+                                atomic_inc(&cur_trans->use_count);
                                 break;
                         }
-                        schedule();
-                        finish_wait(&info->transaction_throttle, &wait);
-                } while (thr == atomic_read(&info->throttle_gen));
-                harder_count++;
-
-                if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
-                    harder_count < 2)
-                        goto harder;
+                        if (t->transid > transid)
+                                break;
+                }
+                spin_unlock(&root->fs_info->trans_lock);
+                ret = -EINVAL;
+                if (!cur_trans)
+                        goto out;  /* bad transid */
+        } else {
+                /* find newest transaction that is committing | committed */
+                spin_lock(&root->fs_info->trans_lock);
+                list_for_each_entry_reverse(t, &root->fs_info->trans_list,
+                                            list) {
+                        if (t->in_commit) {
+                                if (t->commit_done)
+                                        break;
+                                cur_trans = t;
+                                atomic_inc(&cur_trans->use_count);
+                                break;
+                        }
+                }
+                spin_unlock(&root->fs_info->trans_lock);
+                if (!cur_trans)
+                        goto out;  /* nothing committing|committed */
+        }
 
-                if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
-                    harder_count < 10)
-                        goto harder;
+        wait_for_commit(root, cur_trans);
 
-                if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
-                    harder_count < 20)
-                        goto harder;
-        }
+        put_transaction(cur_trans);
+        ret = 0;
+out:
+        return ret;
 }
-#endif
 
 void btrfs_throttle(struct btrfs_root *root)
 {
-        mutex_lock(&root->fs_info->trans_mutex);
-        if (!root->fs_info->open_ioctl_trans)
+        if (!atomic_read(&root->fs_info->open_ioctl_trans))
                 wait_current_trans(root);
-        mutex_unlock(&root->fs_info->trans_mutex);
 }
 
 static int should_end_transaction(struct btrfs_trans_handle *trans,
@@ -336,6 +446,7 @@ int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
         struct btrfs_transaction *cur_trans = trans->transaction;
         int updates;
 
+        smp_mb();
         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
                 return 1;
 
@@ -348,12 +459,17 @@ int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 }
 
 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
-                          struct btrfs_root *root, int throttle)
+                          struct btrfs_root *root, int throttle, int lock)
 {
         struct btrfs_transaction *cur_trans = trans->transaction;
         struct btrfs_fs_info *info = root->fs_info;
         int count = 0;
 
+        if (--trans->use_count) {
+                trans->block_rsv = trans->orig_rsv;
+                return 0;
+        }
+
         while (count < 4) {
                 unsigned long cur = trans->delayed_ref_updates;
                 trans->delayed_ref_updates = 0;
@@ -376,26 +492,27 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 
         btrfs_trans_release_metadata(trans, root);
 
-        if (!root->fs_info->open_ioctl_trans &&
-            should_end_transaction(trans, root))
+        if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
+            should_end_transaction(trans, root)) {
                 trans->transaction->blocked = 1;
+                smp_wmb();
+        }
 
-        if (cur_trans->blocked && !cur_trans->in_commit) {
+        if (lock && cur_trans->blocked && !cur_trans->in_commit) {
                 if (throttle)
                         return btrfs_commit_transaction(trans, root);
                 else
                         wake_up_process(info->transaction_kthread);
         }
 
-        mutex_lock(&info->trans_mutex);
         WARN_ON(cur_trans != info->running_transaction);
-        WARN_ON(cur_trans->num_writers < 1);
-        cur_trans->num_writers--;
+        WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
+        atomic_dec(&cur_trans->num_writers);
 
+        smp_mb();
         if (waitqueue_active(&cur_trans->writer_wait))
                 wake_up(&cur_trans->writer_wait);
         put_transaction(cur_trans);
-        mutex_unlock(&info->trans_mutex);
 
         if (current->journal_info == trans)
                 current->journal_info = NULL;
@@ -411,13 +528,40 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
                           struct btrfs_root *root)
 {
-        return __btrfs_end_transaction(trans, root, 0);
+        int ret;
+
+        ret = __btrfs_end_transaction(trans, root, 0, 1);
+        if (ret)
+                return ret;
+        return 0;
 }
 
 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
                                    struct btrfs_root *root)
 {
-        return __btrfs_end_transaction(trans, root, 1);
+        int ret;
+
+        ret = __btrfs_end_transaction(trans, root, 1, 1);
+        if (ret)
+                return ret;
+        return 0;
+}
+
+int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
+                                 struct btrfs_root *root)
+{
+        int ret;
+
+        ret = __btrfs_end_transaction(trans, root, 0, 0);
+        if (ret)
+                return ret;
+        return 0;
+}
+
+int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
+                                struct btrfs_root *root)
+{
+        return __btrfs_end_transaction(trans, root, 1, 1);
 }
 
 /*
@@ -643,9 +787,9 @@ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
  */
 int btrfs_add_dead_root(struct btrfs_root *root)
 {
-        mutex_lock(&root->fs_info->trans_mutex);
+        spin_lock(&root->fs_info->trans_lock);
         list_add(&root->root_list, &root->fs_info->dead_roots);
-        mutex_unlock(&root->fs_info->trans_mutex);
+        spin_unlock(&root->fs_info->trans_lock);
         return 0;
 }
 
@@ -661,6 +805,7 @@ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
         int ret;
         int err = 0;
 
+        spin_lock(&fs_info->fs_roots_radix_lock);
         while (1) {
                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
                                                  (void **)gang, 0,
@@ -673,13 +818,20 @@ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
                                         (unsigned long)root->root_key.objectid,
                                         BTRFS_ROOT_TRANS_TAG);
+                        spin_unlock(&fs_info->fs_roots_radix_lock);
 
                         btrfs_free_log(trans, root);
                         btrfs_update_reloc_root(trans, root);
                         btrfs_orphan_commit_root(trans, root);
 
+                        btrfs_save_ino_cache(root, trans);
+
                         if (root->commit_root != root->node) {
+                                mutex_lock(&root->fs_commit_mutex);
                                 switch_commit_root(root);
+                                btrfs_unpin_free_ino(root);
+                                mutex_unlock(&root->fs_commit_mutex);
+
                                 btrfs_set_root_node(&root->root_item,
                                                     root->node);
                         }
@@ -687,10 +839,12 @@ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
                         err = btrfs_update_root(trans, fs_info->tree_root,
                                                 &root->root_key,
                                                 &root->root_item);
+                        spin_lock(&fs_info->fs_roots_radix_lock);
                         if (err)
                                 break;
                 }
         }
+        spin_unlock(&fs_info->fs_roots_radix_lock);
         return err;
 }
 
@@ -720,104 +874,13 @@ int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
                 btrfs_btree_balance_dirty(info->tree_root, nr);
                 cond_resched();
 
-                if (root->fs_info->closing || ret != -EAGAIN)
+                if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
                         break;
         }
         root->defrag_running = 0;
         return ret;
 }
 
-#if 0
-/*
- * when dropping snapshots, we generate a ton of delayed refs, and it makes
- * sense not to join the transaction while it is trying to flush the current
- * queue of delayed refs out.
- *
- * This is used by the drop snapshot code only
- */
-static noinline int wait_transaction_pre_flush(struct btrfs_fs_info *info)
-{
-        DEFINE_WAIT(wait);
-
-        mutex_lock(&info->trans_mutex);
-        while (info->running_transaction &&
-               info->running_transaction->delayed_refs.flushing) {
-                prepare_to_wait(&info->transaction_wait, &wait,
-                                TASK_UNINTERRUPTIBLE);
-                mutex_unlock(&info->trans_mutex);
-
-                schedule();
-
-                mutex_lock(&info->trans_mutex);
-                finish_wait(&info->transaction_wait, &wait);
-        }
-        mutex_unlock(&info->trans_mutex);
-        return 0;
-}
-
-/*
- * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
- * all of them
- */
-int btrfs_drop_dead_root(struct btrfs_root *root)
-{
-        struct btrfs_trans_handle *trans;
-        struct btrfs_root *tree_root = root->fs_info->tree_root;
-        unsigned long nr;
-        int ret;
-
-        while (1) {
-                /*
-                 * we don't want to jump in and create a bunch of
-                 * delayed refs if the transaction is starting to close
-                 */
-                wait_transaction_pre_flush(tree_root->fs_info);
-                trans = btrfs_start_transaction(tree_root, 1);
-
-                /*
-                 * we've joined a transaction, make sure it isn't
-                 * closing right now
-                 */
-                if (trans->transaction->delayed_refs.flushing) {
-                        btrfs_end_transaction(trans, tree_root);
-                        continue;
-                }
-
-                ret = btrfs_drop_snapshot(trans, root);
-                if (ret != -EAGAIN)
-                        break;
-
-                ret = btrfs_update_root(trans, tree_root,
-                                        &root->root_key,
-                                        &root->root_item);
-                if (ret)
-                        break;
-
-                nr = trans->blocks_used;
-                ret = btrfs_end_transaction(trans, tree_root);
-                BUG_ON(ret);
-
-                btrfs_btree_balance_dirty(tree_root, nr);
-                cond_resched();
-        }
-        BUG_ON(ret);
-
-        ret = btrfs_del_root(trans, tree_root, &root->root_key);
-        BUG_ON(ret);
-
-        nr = trans->blocks_used;
-        ret = btrfs_end_transaction(trans, tree_root);
-        BUG_ON(ret);
-
-        free_extent_buffer(root->node);
-        free_extent_buffer(root->commit_root);
-        kfree(root);
-
-        btrfs_btree_balance_dirty(tree_root, nr);
-        return ret;
-}
-#endif
-
 /*
  * new snapshots need to be created at a very specific time in the
  * transaction commit.  This does the actual creation
@@ -832,14 +895,15 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         struct btrfs_root *root = pending->root;
         struct btrfs_root *parent_root;
         struct inode *parent_inode;
+        struct dentry *parent;
         struct dentry *dentry;
         struct extent_buffer *tmp;
         struct extent_buffer *old;
         int ret;
-        int retries = 0;
         u64 to_reserve = 0;
         u64 index = 0;
         u64 objectid;
+        u64 root_flags;
 
         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
         if (!new_root_item) {
@@ -847,7 +911,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
                 goto fail;
         }
 
-        ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
+        ret = btrfs_find_free_objectid(tree_root, &objectid);
         if (ret) {
                 pending->error = ret;
                 goto fail;
@@ -858,7 +922,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 
         if (to_reserve > 0) {
                 ret = btrfs_block_rsv_add(trans, root, &pending->block_rsv,
-                                          to_reserve, &retries);
+                                          to_reserve);
                 if (ret) {
                         pending->error = ret;
                         goto fail;
@@ -872,7 +936,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         trans->block_rsv = &pending->block_rsv;
 
         dentry = pending->dentry;
-        parent_inode = dentry->d_parent->d_inode;
+        parent = dget_parent(dentry);
+        parent_inode = parent->d_inode;
         parent_root = BTRFS_I(parent_inode)->root;
         record_root_in_trans(trans, parent_root);
 
@@ -883,7 +948,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         BUG_ON(ret);
         ret = btrfs_insert_dir_item(trans, parent_root,
                                 dentry->d_name.name, dentry->d_name.len,
-                                parent_inode->i_ino, &key,
+                                parent_inode, &key,
                                 BTRFS_FT_DIR, index);
         BUG_ON(ret);
 
@@ -892,9 +957,26 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         ret = btrfs_update_inode(trans, parent_root, parent_inode);
         BUG_ON(ret);
 
+        /*
+         * pull in the delayed directory update
+         * and the delayed inode item
+         * otherwise we corrupt the FS during
+         * snapshot
+         */
+        ret = btrfs_run_delayed_items(trans, root);
+        BUG_ON(ret);
+
         record_root_in_trans(trans, root);
         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
+        btrfs_check_and_init_root_item(new_root_item);
+
+        root_flags = btrfs_root_flags(new_root_item);
+        if (pending->readonly)
+                root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
+        else
+                root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
+        btrfs_set_root_flags(new_root_item, root_flags);
 
         old = btrfs_lock_root_node(root);
         btrfs_cow_block(trans, root, old, NULL, 0, &old);
@@ -917,9 +999,10 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
          */
         ret = btrfs_add_root_ref(trans, tree_root, objectid,
                                  parent_root->root_key.objectid,
-                                 parent_inode->i_ino, index,
+                                 btrfs_ino(parent_inode), index,
                                  dentry->d_name.name, dentry->d_name.len);
         BUG_ON(ret);
+        dput(parent);
 
         key.offset = (u64)-1;
         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
@@ -966,33 +1049,152 @@ static void update_super_roots(struct btrfs_root *root)
         super->root = root_item->bytenr;
         super->generation = root_item->generation;
         super->root_level = root_item->level;
+        if (super->cache_generation != 0 || btrfs_test_opt(root, SPACE_CACHE))
+                super->cache_generation = root_item->generation;
 }
 
 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
 {
         int ret = 0;
-        spin_lock(&info->new_trans_lock);
+        spin_lock(&info->trans_lock);
         if (info->running_transaction)
                 ret = info->running_transaction->in_commit;
-        spin_unlock(&info->new_trans_lock);
+        spin_unlock(&info->trans_lock);
         return ret;
 }
 
 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
 {
         int ret = 0;
-        spin_lock(&info->new_trans_lock);
+        spin_lock(&info->trans_lock);
         if (info->running_transaction)
                 ret = info->running_transaction->blocked;
-        spin_unlock(&info->new_trans_lock);
+        spin_unlock(&info->trans_lock);
         return ret;
 }
 
+/*
+ * wait for the current transaction commit to start and block subsequent
+ * transaction joins
+ */
+static void wait_current_trans_commit_start(struct btrfs_root *root,
+                                            struct btrfs_transaction *trans)
+{
+        DEFINE_WAIT(wait);
+
+        if (trans->in_commit)
+                return;
+
+        while (1) {
+                prepare_to_wait(&root->fs_info->transaction_blocked_wait, &wait,
+                                TASK_UNINTERRUPTIBLE);
+                if (trans->in_commit) {
+                        finish_wait(&root->fs_info->transaction_blocked_wait,
+                                    &wait);
+                        break;
+                }
+                schedule();
+                finish_wait(&root->fs_info->transaction_blocked_wait, &wait);
+        }
+}
+
+/*
+ * wait for the current transaction to start and then become unblocked.
+ * caller holds ref.
+ */
+static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
+                                         struct btrfs_transaction *trans)
+{
+        DEFINE_WAIT(wait);
+
+        if (trans->commit_done || (trans->in_commit && !trans->blocked))
+                return;
+
+        while (1) {
+                prepare_to_wait(&root->fs_info->transaction_wait, &wait,
+                                TASK_UNINTERRUPTIBLE);
+                if (trans->commit_done ||
+                    (trans->in_commit && !trans->blocked)) {
+                        finish_wait(&root->fs_info->transaction_wait,
+                                    &wait);
+                        break;
+                }
+                schedule();
+                finish_wait(&root->fs_info->transaction_wait,
+                            &wait);
+        }
+}
+
+/*
+ * commit transactions asynchronously. once btrfs_commit_transaction_async
+ * returns, any subsequent transaction will not be allowed to join.
+ */
+struct btrfs_async_commit {
+        struct btrfs_trans_handle *newtrans;
+        struct btrfs_root *root;
+        struct delayed_work work;
+};
+
+static void do_async_commit(struct work_struct *work)
+{
+        struct btrfs_async_commit *ac =
+                container_of(work, struct btrfs_async_commit, work.work);
+
+        btrfs_commit_transaction(ac->newtrans, ac->root);
+        kfree(ac);
+}
+
+int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
+                                   struct btrfs_root *root,
+                                   int wait_for_unblock)
+{
+        struct btrfs_async_commit *ac;
+        struct btrfs_transaction *cur_trans;
+
+        ac = kmalloc(sizeof(*ac), GFP_NOFS);
+        if (!ac)
+                return -ENOMEM;
+
+        INIT_DELAYED_WORK(&ac->work, do_async_commit);
+        ac->root = root;
+        ac->newtrans = btrfs_join_transaction(root);
+        if (IS_ERR(ac->newtrans)) {
+                int err = PTR_ERR(ac->newtrans);
+                kfree(ac);
+                return err;
+        }
+
+        /* take transaction reference */
+        cur_trans = trans->transaction;
+        atomic_inc(&cur_trans->use_count);
+
+        btrfs_end_transaction(trans, root);
+        schedule_delayed_work(&ac->work, 0);
+
+        /* wait for transaction to start and unblock */
+        if (wait_for_unblock)
+                wait_current_trans_commit_start_and_unblock(root, cur_trans);
+        else
+                wait_current_trans_commit_start(root, cur_trans);
+
+        if (current->journal_info == trans)
+                current->journal_info = NULL;
+
+        put_transaction(cur_trans);
+        return 0;
+}
+
+/*
+ * btrfs_transaction state sequence:
+ *    in_commit = 0, blocked = 0  (initial)
+ *    in_commit = 1, blocked = 1
+ *    blocked = 0
+ *    commit_done = 1
+ */
 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                              struct btrfs_root *root)
 {
         unsigned long joined = 0;
-        unsigned long timeout = 1;
         struct btrfs_transaction *cur_trans;
         struct btrfs_transaction *prev_trans = NULL;
         DEFINE_WAIT(wait);
@@ -1021,36 +1223,41 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
         ret = btrfs_run_delayed_refs(trans, root, 0);
         BUG_ON(ret);
 
-        mutex_lock(&root->fs_info->trans_mutex);
+        spin_lock(&cur_trans->commit_lock);
         if (cur_trans->in_commit) {
-                cur_trans->use_count++;
-                mutex_unlock(&root->fs_info->trans_mutex);
+                spin_unlock(&cur_trans->commit_lock);
+                atomic_inc(&cur_trans->use_count);
                 btrfs_end_transaction(trans, root);
 
                 ret = wait_for_commit(root, cur_trans);
                 BUG_ON(ret);
 
-                mutex_lock(&root->fs_info->trans_mutex);
                 put_transaction(cur_trans);
-                mutex_unlock(&root->fs_info->trans_mutex);
 
                 return 0;
         }
 
         trans->transaction->in_commit = 1;
         trans->transaction->blocked = 1;
+        spin_unlock(&cur_trans->commit_lock);
+        wake_up(&root->fs_info->transaction_blocked_wait);
+
+        spin_lock(&root->fs_info->trans_lock);
         if (cur_trans->list.prev != &root->fs_info->trans_list) {
                 prev_trans = list_entry(cur_trans->list.prev,
                                         struct btrfs_transaction, list);
                 if (!prev_trans->commit_done) {
-                        prev_trans->use_count++;
-                        mutex_unlock(&root->fs_info->trans_mutex);
+                        atomic_inc(&prev_trans->use_count);
+                        spin_unlock(&root->fs_info->trans_lock);
 
                         wait_for_commit(root, prev_trans);
 
-                        mutex_lock(&root->fs_info->trans_mutex);
                         put_transaction(prev_trans);
+                } else {
+                        spin_unlock(&root->fs_info->trans_lock);
                 }
+        } else {
+                spin_unlock(&root->fs_info->trans_lock);
         }
 
         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
@@ -1058,17 +1265,12 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 
         do {
                 int snap_pending = 0;
+
                 joined = cur_trans->num_joined;
                 if (!list_empty(&trans->transaction->pending_snapshots))
                         snap_pending = 1;
 
                 WARN_ON(cur_trans != trans->transaction);
-                if (cur_trans->num_writers > 1)
-                        timeout = MAX_SCHEDULE_TIMEOUT;
-                else if (should_grow)
-                        timeout = 1;
-
-                mutex_unlock(&root->fs_info->trans_mutex);
 
                 if (flush_on_commit || snap_pending) {
                         btrfs_start_delalloc_inodes(root, 1);
@@ -1076,6 +1278,9 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                         BUG_ON(ret);
                 }
 
+                ret = btrfs_run_delayed_items(trans, root);
+                BUG_ON(ret);
+
                 /*
                  * rename don't use btrfs_join_transaction, so, once we
                  * set the transaction to blocked above, we aren't going
@@ -1088,23 +1293,51 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                 prepare_to_wait(&cur_trans->writer_wait, &wait,
                                 TASK_UNINTERRUPTIBLE);
 
-                smp_mb();
-                if (cur_trans->num_writers > 1 || should_grow)
-                        schedule_timeout(timeout);
+                if (atomic_read(&cur_trans->num_writers) > 1)
+                        schedule_timeout(MAX_SCHEDULE_TIMEOUT);
+                else if (should_grow)
+                        schedule_timeout(1);
 
-                mutex_lock(&root->fs_info->trans_mutex);
                 finish_wait(&cur_trans->writer_wait, &wait);
-        } while (cur_trans->num_writers > 1 ||
+        } while (atomic_read(&cur_trans->num_writers) > 1 ||
                  (should_grow && cur_trans->num_joined != joined));
 
+        /*
+         * Ok now we need to make sure to block out any other joins while we
+         * commit the transaction.  We could have started a join before setting
+         * no_join so make sure to wait for num_writers to == 1 again.
+         */
+        spin_lock(&root->fs_info->trans_lock);
+        root->fs_info->trans_no_join = 1;
+        spin_unlock(&root->fs_info->trans_lock);
+        wait_event(cur_trans->writer_wait,
+                   atomic_read(&cur_trans->num_writers) == 1);
+
+        /*
+         * the reloc mutex makes sure that we stop
+         * the balancing code from coming in and moving
+         * extents around in the middle of the commit
+         */
+        mutex_lock(&root->fs_info->reloc_mutex);
+
+        ret = btrfs_run_delayed_items(trans, root);
+        BUG_ON(ret);
+
         ret = create_pending_snapshots(trans, root->fs_info);
         BUG_ON(ret);
 
         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
         BUG_ON(ret);
 
+        /*
+         * make sure none of the code above managed to slip in a
+         * delayed item
+         */
+        btrfs_assert_delayed_root_empty(root);
+
         WARN_ON(cur_trans != trans->transaction);
 
+        btrfs_scrub_pause(root);
         /* btrfs_commit_tree_roots is responsible for getting the
          * various roots consistent with each other.  Every pointer
          * in the tree of tree roots has to point to the most up to date
@@ -1134,9 +1367,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
         btrfs_prepare_extent_commit(trans, root);
 
         cur_trans = root->fs_info->running_transaction;
-        spin_lock(&root->fs_info->new_trans_lock);
-        root->fs_info->running_transaction = NULL;
-        spin_unlock(&root->fs_info->new_trans_lock);
 
         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
                             root->fs_info->tree_root->node);
@@ -1157,10 +1387,14 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                sizeof(root->fs_info->super_copy));
 
         trans->transaction->blocked = 0;
+        spin_lock(&root->fs_info->trans_lock);
+        root->fs_info->running_transaction = NULL;
+        root->fs_info->trans_no_join = 0;
+        spin_unlock(&root->fs_info->trans_lock);
+        mutex_unlock(&root->fs_info->reloc_mutex);
 
         wake_up(&root->fs_info->transaction_wait);
 
-        mutex_unlock(&root->fs_info->trans_mutex);
         ret = btrfs_write_and_wait_transaction(trans, root);
         BUG_ON(ret);
         write_ctree_super(trans, root, 0);
@@ -1173,18 +1407,22 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 
         btrfs_finish_extent_commit(trans, root);
 
-        mutex_lock(&root->fs_info->trans_mutex);
-
         cur_trans->commit_done = 1;
 
         root->fs_info->last_trans_committed = cur_trans->transid;
 
         wake_up(&cur_trans->commit_wait);
 
+        spin_lock(&root->fs_info->trans_lock);
+        list_del_init(&cur_trans->list);
+        spin_unlock(&root->fs_info->trans_lock);
+
         put_transaction(cur_trans);
         put_transaction(cur_trans);
 
-        mutex_unlock(&root->fs_info->trans_mutex);
+        trace_btrfs_transaction_commit(root);
+
+        btrfs_scrub_continue(root);
 
         if (current->journal_info == trans)
                 current->journal_info = NULL;
@@ -1205,14 +1443,16 @@ int btrfs_clean_old_snapshots(struct btrfs_root *root)
         LIST_HEAD(list);
         struct btrfs_fs_info *fs_info = root->fs_info;
 
-        mutex_lock(&fs_info->trans_mutex);
+        spin_lock(&fs_info->trans_lock);
         list_splice_init(&fs_info->dead_roots, &list);
-        mutex_unlock(&fs_info->trans_mutex);
+        spin_unlock(&fs_info->trans_lock);
 
         while (!list_empty(&list)) {
                 root = list_entry(list.next, struct btrfs_root, root_list);
                 list_del(&root->root_list);
 
+                btrfs_kill_all_delayed_nodes(root);
+
                 if (btrfs_header_backref_rev(root->node) <
                     BTRFS_MIXED_BACKREF_REV)
                         btrfs_drop_snapshot(root, NULL, 0);