1 files changed, 210 insertions, 24 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 66e4c66cc63b..1fffbc017bdf 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -163,6 +163,7 @@ enum btrfs_trans_type {
         TRANS_START,
         TRANS_JOIN,
         TRANS_USERSPACE,
+        TRANS_JOIN_NOLOCK,
 };
 
 static int may_wait_transaction(struct btrfs_root *root, int type)
@@ -179,14 +180,14 @@ static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 {
         struct btrfs_trans_handle *h;
         struct btrfs_transaction *cur_trans;
-        int retries = 0;
         int ret;
 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 (type != TRANS_JOIN_NOLOCK)
+                mutex_lock(&root->fs_info->trans_mutex);
         if (may_wait_transaction(root, type))
                 wait_current_trans(root);
 
@@ -195,7 +196,8 @@ again:
 
         cur_trans = root->fs_info->running_transaction;
         cur_trans->use_count++;
-        mutex_unlock(&root->fs_info->trans_mutex);
+        if (type != TRANS_JOIN_NOLOCK)
+                mutex_unlock(&root->fs_info->trans_mutex);
 
         h->transid = cur_trans->transid;
         h->transaction = cur_trans;
@@ -212,8 +214,7 @@ again:
         }
 
         if (num_items > 0) {
-                ret = btrfs_trans_reserve_metadata(h, root, num_items,
-                                                   &retries);
+                ret = btrfs_trans_reserve_metadata(h, root, num_items);
                 if (ret == -EAGAIN) {
                         btrfs_commit_transaction(h, root);
                         goto again;
@@ -224,9 +225,11 @@ again:
                 }
         }
 
-        mutex_lock(&root->fs_info->trans_mutex);
+        if (type != TRANS_JOIN_NOLOCK)
+                mutex_lock(&root->fs_info->trans_mutex);
         record_root_in_trans(h, root);
-        mutex_unlock(&root->fs_info->trans_mutex);
+        if (type != TRANS_JOIN_NOLOCK)
+                mutex_unlock(&root->fs_info->trans_mutex);
 
         if (!current->journal_info && type != TRANS_USERSPACE)
                 current->journal_info = h;
@@ -244,6 +247,12 @@ struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
         return start_transaction(root, 0, TRANS_JOIN);
 }
 
+struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root,
+                                                          int num_blocks)
+{
+        return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
+}
+
 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
                                                          int num_blocks)
 {
@@ -270,6 +279,58 @@ static noinline int wait_for_commit(struct btrfs_root *root,
         return 0;
 }
 
+int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
+{
+        struct btrfs_transaction *cur_trans = NULL, *t;
+        int ret;
+
+        mutex_lock(&root->fs_info->trans_mutex);
+
+        ret = 0;
+        if (transid) {
+                if (transid <= root->fs_info->last_trans_committed)
+                        goto out_unlock;
+
+                /* find specified transaction */
+                list_for_each_entry(t, &root->fs_info->trans_list, list) {
+                        if (t->transid == transid) {
+                                cur_trans = t;
+                                break;
+                        }
+                        if (t->transid > transid)
+                                break;
+                }
+                ret = -EINVAL;
+                if (!cur_trans)
+                        goto out_unlock;  /* bad transid */
+        } else {
+                /* find newest transaction that is committing | committed */
+                list_for_each_entry_reverse(t, &root->fs_info->trans_list,
+                                            list) {
+                        if (t->in_commit) {
+                                if (t->commit_done)
+                                        goto out_unlock;
+                                cur_trans = t;
+                                break;
+                        }
+                }
+                if (!cur_trans)
+                        goto out_unlock;  /* nothing committing|committed */
+        }
+
+        cur_trans->use_count++;
+        mutex_unlock(&root->fs_info->trans_mutex);
+
+        wait_for_commit(root, cur_trans);
+
+        mutex_lock(&root->fs_info->trans_mutex);
+        put_transaction(cur_trans);
+        ret = 0;
+out_unlock:
+        mutex_unlock(&root->fs_info->trans_mutex);
+        return ret;
+}
+
 #if 0
 /*
  * rate limit against the drop_snapshot code.  This helps to slow down new
@@ -348,7 +409,7 @@ 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;
@@ -376,26 +437,29 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 
         btrfs_trans_release_metadata(trans, root);
 
-        if (!root->fs_info->open_ioctl_trans &&
+        if (lock && !root->fs_info->open_ioctl_trans &&
             should_end_transaction(trans, root))
                 trans->transaction->blocked = 1;
 
-        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);
+        if (lock)
+                mutex_lock(&info->trans_mutex);
         WARN_ON(cur_trans != info->running_transaction);
         WARN_ON(cur_trans->num_writers < 1);
         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 (lock)
+                mutex_unlock(&info->trans_mutex);
 
         if (current->journal_info == trans)
                 current->journal_info = NULL;
@@ -411,13 +475,19 @@ 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);
+        return __btrfs_end_transaction(trans, root, 0, 1);
 }
 
 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
                                    struct btrfs_root *root)
 {
-        return __btrfs_end_transaction(trans, root, 1);
+        return __btrfs_end_transaction(trans, root, 1, 1);
+}
+
+int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
+                                 struct btrfs_root *root)
+{
+        return __btrfs_end_transaction(trans, root, 0, 0);
 }
 
 /*
@@ -836,7 +906,6 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         struct extent_buffer *tmp;
         struct extent_buffer *old;
         int ret;
-        int retries = 0;
         u64 to_reserve = 0;
         u64 index = 0;
         u64 objectid;
@@ -858,7 +927,7 @@ 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;
@@ -966,6 +1035,8 @@ 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)
@@ -988,11 +1059,127 @@ int btrfs_transaction_blocked(struct btrfs_fs_info *info)
         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;
+                }
+                mutex_unlock(&root->fs_info->trans_mutex);
+                schedule();
+                mutex_lock(&root->fs_info->trans_mutex);
+                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;
+                }
+                mutex_unlock(&root->fs_info->trans_mutex);
+                schedule();
+                mutex_lock(&root->fs_info->trans_mutex);
+                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);
+        BUG_ON(!ac);
+
+        INIT_DELAYED_WORK(&ac->work, do_async_commit);
+        ac->root = root;
+        ac->newtrans = btrfs_join_transaction(root, 0);
+
+        /* take transaction reference */
+        mutex_lock(&root->fs_info->trans_mutex);
+        cur_trans = trans->transaction;
+        cur_trans->use_count++;
+        mutex_unlock(&root->fs_info->trans_mutex);
+
+        btrfs_end_transaction(trans, root);
+        schedule_delayed_work(&ac->work, 0);
+
+        /* wait for transaction to start and unblock */
+        mutex_lock(&root->fs_info->trans_mutex);
+        if (wait_for_unblock)
+                wait_current_trans_commit_start_and_unblock(root, cur_trans);
+        else
+                wait_current_trans_commit_start(root, cur_trans);
+        put_transaction(cur_trans);
+        mutex_unlock(&root->fs_info->trans_mutex);
+
+        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);
@@ -1039,6 +1226,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 
         trans->transaction->in_commit = 1;
         trans->transaction->blocked = 1;
+        wake_up(&root->fs_info->transaction_blocked_wait);
+
         if (cur_trans->list.prev != &root->fs_info->trans_list) {
                 prev_trans = list_entry(cur_trans->list.prev,
                                         struct btrfs_transaction, list);
@@ -1063,11 +1252,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                         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) {
@@ -1089,8 +1273,10 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                                 TASK_UNINTERRUPTIBLE);
 
                 smp_mb();
-                if (cur_trans->num_writers > 1 || should_grow)
-                        schedule_timeout(timeout);
+                if (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);