1 files changed, 139 insertions, 271 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 01b143605ec1..2e177d7f4bb9 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -25,7 +25,6 @@
 #include "disk-io.h"
 #include "transaction.h"
 #include "locking.h"
-#include "ref-cache.h"
 #include "tree-log.h"
 
 #define BTRFS_ROOT_TRANS_TAG 0
@@ -94,45 +93,37 @@ 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
  */
-noinline int btrfs_record_root_in_trans(struct btrfs_root *root)
+static noinline int record_root_in_trans(struct btrfs_trans_handle *trans,
+                                         struct btrfs_root *root)
 {
-        struct btrfs_dirty_root *dirty;
-        u64 running_trans_id = root->fs_info->running_transaction->transid;
-        if (root->ref_cows && root->last_trans < running_trans_id) {
+        if (root->ref_cows && root->last_trans < trans->transid) {
                 WARN_ON(root == root->fs_info->extent_root);
-                if (root->root_item.refs != 0) {
-                        radix_tree_tag_set(&root->fs_info->fs_roots_radix,
-                                   (unsigned long)root->root_key.objectid,
-                                   BTRFS_ROOT_TRANS_TAG);
-
-                        dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
-                        BUG_ON(!dirty);
-                        dirty->root = kmalloc(sizeof(*dirty->root), GFP_NOFS);
-                        BUG_ON(!dirty->root);
-                        dirty->latest_root = root;
-                        INIT_LIST_HEAD(&dirty->list);
-
-                        root->commit_root = btrfs_root_node(root);
-
-                        memcpy(dirty->root, root, sizeof(*root));
-                        spin_lock_init(&dirty->root->node_lock);
-                        spin_lock_init(&dirty->root->list_lock);
-                        mutex_init(&dirty->root->objectid_mutex);
-                        mutex_init(&dirty->root->log_mutex);
-                        INIT_LIST_HEAD(&dirty->root->dead_list);
-                        dirty->root->node = root->commit_root;
-                        dirty->root->commit_root = NULL;
+                WARN_ON(root->root_item.refs == 0);
+                WARN_ON(root->commit_root != root->node);
+
+                radix_tree_tag_set(&root->fs_info->fs_roots_radix,
+                           (unsigned long)root->root_key.objectid,
+                           BTRFS_ROOT_TRANS_TAG);
+                root->last_trans = trans->transid;
+                btrfs_init_reloc_root(trans, root);
+        }
+        return 0;
+}
 
-                        spin_lock(&root->list_lock);
-                        list_add(&dirty->root->dead_list, &root->dead_list);
-                        spin_unlock(&root->list_lock);
+int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
+                               struct btrfs_root *root)
+{
+        if (!root->ref_cows)
+                return 0;
 
-                        root->dirty_root = dirty;
-                } else {
-                        WARN_ON(1);
-                }
-                root->last_trans = running_trans_id;
+        mutex_lock(&root->fs_info->trans_mutex);
+        if (root->last_trans == trans->transid) {
+                mutex_unlock(&root->fs_info->trans_mutex);
+                return 0;
         }
+
+        record_root_in_trans(trans, root);
+        mutex_unlock(&root->fs_info->trans_mutex);
         return 0;
 }
 
@@ -181,7 +172,6 @@ static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
         ret = join_transaction(root);
         BUG_ON(ret);
 
-        btrfs_record_root_in_trans(root);
         h->transid = root->fs_info->running_transaction->transid;
         h->transaction = root->fs_info->running_transaction;
         h->blocks_reserved = num_blocks;
@@ -192,6 +182,7 @@ static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
         h->delayed_ref_updates = 0;
 
         root->fs_info->running_transaction->use_count++;
+        record_root_in_trans(h, root);
         mutex_unlock(&root->fs_info->trans_mutex);
         return h;
 }
@@ -233,6 +224,7 @@ static noinline int wait_for_commit(struct btrfs_root *root,
         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.
@@ -273,6 +265,7 @@ harder:
                         goto harder;
         }
 }
+#endif
 
 void btrfs_throttle(struct btrfs_root *root)
 {
@@ -280,7 +273,6 @@ void btrfs_throttle(struct btrfs_root *root)
         if (!root->fs_info->open_ioctl_trans)
                 wait_current_trans(root);
         mutex_unlock(&root->fs_info->trans_mutex);
-        throttle_on_drops(root);
 }
 
 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
@@ -323,9 +315,6 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
         memset(trans, 0, sizeof(*trans));
         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 
-        if (throttle)
-                throttle_on_drops(root);
-
         return 0;
 }
 
@@ -462,12 +451,8 @@ static int update_cowonly_root(struct btrfs_trans_handle *trans,
                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
                 if (old_root_bytenr == root->node->start)
                         break;
-                btrfs_set_root_bytenr(&root->root_item,
-                                       root->node->start);
-                btrfs_set_root_level(&root->root_item,
-                                     btrfs_header_level(root->node));
-                btrfs_set_root_generation(&root->root_item, trans->transid);
 
+                btrfs_set_root_node(&root->root_item, root->node);
                 ret = btrfs_update_root(trans, tree_root,
                                         &root->root_key,
                                         &root->root_item);
@@ -477,14 +462,16 @@ static int update_cowonly_root(struct btrfs_trans_handle *trans,
                 ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
                 BUG_ON(ret);
         }
+        free_extent_buffer(root->commit_root);
+        root->commit_root = btrfs_root_node(root);
         return 0;
 }
 
 /*
  * update all the cowonly tree roots on disk
  */
-int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
-                            struct btrfs_root *root)
+static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
+                                         struct btrfs_root *root)
 {
         struct btrfs_fs_info *fs_info = root->fs_info;
         struct list_head *next;
@@ -520,118 +507,54 @@ int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
  * a dirty root struct and adds it into the list of dead roots that need to
  * be deleted
  */
-int btrfs_add_dead_root(struct btrfs_root *root, struct btrfs_root *latest)
+int btrfs_add_dead_root(struct btrfs_root *root)
 {
-        struct btrfs_dirty_root *dirty;
-
-        dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
-        if (!dirty)
-                return -ENOMEM;
-        dirty->root = root;
-        dirty->latest_root = latest;
-
         mutex_lock(&root->fs_info->trans_mutex);
-        list_add(&dirty->list, &latest->fs_info->dead_roots);
+        list_add(&root->root_list, &root->fs_info->dead_roots);
         mutex_unlock(&root->fs_info->trans_mutex);
         return 0;
 }
 
 /*
- * at transaction commit time we need to schedule the old roots for
- * deletion via btrfs_drop_snapshot.  This runs through all the
- * reference counted roots that were modified in the current
- * transaction and puts them into the drop list
+ * update all the cowonly tree roots on disk
  */
-static noinline int add_dirty_roots(struct btrfs_trans_handle *trans,
-                                    struct radix_tree_root *radix,
-                                    struct list_head *list)
+static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
+                                    struct btrfs_root *root)
 {
-        struct btrfs_dirty_root *dirty;
         struct btrfs_root *gang[8];
-        struct btrfs_root *root;
+        struct btrfs_fs_info *fs_info = root->fs_info;
         int i;
         int ret;
         int err = 0;
-        u32 refs;
 
         while (1) {
-                ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
+                ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
+                                                 (void **)gang, 0,
                                                  ARRAY_SIZE(gang),
                                                  BTRFS_ROOT_TRANS_TAG);
                 if (ret == 0)
                         break;
                 for (i = 0; i < ret; i++) {
                         root = gang[i];
-                        radix_tree_tag_clear(radix,
-                                     (unsigned long)root->root_key.objectid,
-                                     BTRFS_ROOT_TRANS_TAG);
-
-                        BUG_ON(!root->ref_tree);
-                        dirty = root->dirty_root;
+                        radix_tree_tag_clear(&fs_info->fs_roots_radix,
+                                        (unsigned long)root->root_key.objectid,
+                                        BTRFS_ROOT_TRANS_TAG);
 
                         btrfs_free_log(trans, root);
-                        btrfs_free_reloc_root(trans, root);
-
-                        if (root->commit_root == root->node) {
-                                WARN_ON(root->node->start !=
-                                        btrfs_root_bytenr(&root->root_item));
-
-                                free_extent_buffer(root->commit_root);
-                                root->commit_root = NULL;
-                                root->dirty_root = NULL;
-
-                                spin_lock(&root->list_lock);
-                                list_del_init(&dirty->root->dead_list);
-                                spin_unlock(&root->list_lock);
+                        btrfs_update_reloc_root(trans, root);
 
-                                kfree(dirty->root);
-                                kfree(dirty);
-
-                                /* make sure to update the root on disk
-                                 * so we get any updates to the block used
-                                 * counts
-                                 */
-                                err = btrfs_update_root(trans,
-                                                root->fs_info->tree_root,
-                                                &root->root_key,
-                                                &root->root_item);
+                        if (root->commit_root == root->node)
                                 continue;
-                        }
 
-                        memset(&root->root_item.drop_progress, 0,
-                               sizeof(struct btrfs_disk_key));
-                        root->root_item.drop_level = 0;
-                        root->commit_root = NULL;
-                        root->dirty_root = NULL;
-                        root->root_key.offset = root->fs_info->generation;
-                        btrfs_set_root_bytenr(&root->root_item,
-                                              root->node->start);
-                        btrfs_set_root_level(&root->root_item,
-                                             btrfs_header_level(root->node));
-                        btrfs_set_root_generation(&root->root_item,
-                                                  root->root_key.offset);
-
-                        err = btrfs_insert_root(trans, root->fs_info->tree_root,
+                        free_extent_buffer(root->commit_root);
+                        root->commit_root = btrfs_root_node(root);
+
+                        btrfs_set_root_node(&root->root_item, root->node);
+                        err = btrfs_update_root(trans, fs_info->tree_root,
                                                 &root->root_key,
                                                 &root->root_item);
                         if (err)
                                 break;
-
-                        refs = btrfs_root_refs(&dirty->root->root_item);
-                        btrfs_set_root_refs(&dirty->root->root_item, refs - 1);
-                        err = btrfs_update_root(trans, root->fs_info->tree_root,
-                                                &dirty->root->root_key,
-                                                &dirty->root->root_item);
-
-                        BUG_ON(err);
-                        if (refs == 1) {
-                                list_add(&dirty->list, list);
-                        } else {
-                                WARN_ON(1);
-                                free_extent_buffer(dirty->root->node);
-                                kfree(dirty->root);
-                                kfree(dirty);
-                        }
                 }
         }
         return err;
@@ -688,12 +611,8 @@ static noinline int wait_transaction_pre_flush(struct btrfs_fs_info *info)
                                 TASK_UNINTERRUPTIBLE);
                 mutex_unlock(&info->trans_mutex);
 
-                atomic_dec(&info->throttles);
-                wake_up(&info->transaction_throttle);
-
                 schedule();
 
-                atomic_inc(&info->throttles);
                 mutex_lock(&info->trans_mutex);
                 finish_wait(&info->transaction_wait, &wait);
         }
@@ -705,111 +624,61 @@ static noinline int wait_transaction_pre_flush(struct btrfs_fs_info *info)
  * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
  * all of them
  */
-static noinline int drop_dirty_roots(struct btrfs_root *tree_root,
-                                     struct list_head *list)
+int btrfs_drop_dead_root(struct btrfs_root *root)
 {
-        struct btrfs_dirty_root *dirty;
         struct btrfs_trans_handle *trans;
+        struct btrfs_root *tree_root = root->fs_info->tree_root;
         unsigned long nr;
-        u64 num_bytes;
-        u64 bytes_used;
-        u64 max_useless;
-        int ret = 0;
-        int err;
-
-        while (!list_empty(list)) {
-                struct btrfs_root *root;
-
-                dirty = list_entry(list->prev, struct btrfs_dirty_root, list);
-                list_del_init(&dirty->list);
-
-                num_bytes = btrfs_root_used(&dirty->root->root_item);
-                root = dirty->latest_root;
-                atomic_inc(&root->fs_info->throttles);
-
-                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;
-                        }
-
-                        mutex_lock(&root->fs_info->drop_mutex);
-                        ret = btrfs_drop_snapshot(trans, dirty->root);
-                        if (ret != -EAGAIN)
-                                break;
-                        mutex_unlock(&root->fs_info->drop_mutex);
+        int ret;
 
-                        err = btrfs_update_root(trans,
-                                        tree_root,
-                                        &dirty->root->root_key,
-                                        &dirty->root->root_item);
-                        if (err)
-                                ret = err;
-                        nr = trans->blocks_used;
-                        ret = btrfs_end_transaction(trans, tree_root);
-                        BUG_ON(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);
 
-                        btrfs_btree_balance_dirty(tree_root, nr);
-                        cond_resched();
+                /*
+                 * 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;
                 }
-                BUG_ON(ret);
-                atomic_dec(&root->fs_info->throttles);
-                wake_up(&root->fs_info->transaction_throttle);
 
-                num_bytes -= btrfs_root_used(&dirty->root->root_item);
-                bytes_used = btrfs_root_used(&root->root_item);
-                if (num_bytes) {
-                        mutex_lock(&root->fs_info->trans_mutex);
-                        btrfs_record_root_in_trans(root);
-                        mutex_unlock(&root->fs_info->trans_mutex);
-                        btrfs_set_root_used(&root->root_item,
-                                            bytes_used - num_bytes);
-                }
+                ret = btrfs_drop_snapshot(trans, root);
+                if (ret != -EAGAIN)
+                        break;
 
-                ret = btrfs_del_root(trans, tree_root, &dirty->root->root_key);
-                if (ret) {
-                        BUG();
+                ret = btrfs_update_root(trans, tree_root,
+                                        &root->root_key,
+                                        &root->root_item);
+                if (ret)
                         break;
-                }
-                mutex_unlock(&root->fs_info->drop_mutex);
-
-                spin_lock(&root->list_lock);
-                list_del_init(&dirty->root->dead_list);
-                if (!list_empty(&root->dead_list)) {
-                        struct btrfs_root *oldest;
-                        oldest = list_entry(root->dead_list.prev,
-                                            struct btrfs_root, dead_list);
-                        max_useless = oldest->root_key.offset - 1;
-                } else {
-                        max_useless = root->root_key.offset - 1;
-                }
-                spin_unlock(&root->list_lock);
 
                 nr = trans->blocks_used;
                 ret = btrfs_end_transaction(trans, tree_root);
                 BUG_ON(ret);
 
-                ret = btrfs_remove_leaf_refs(root, max_useless, 0);
-                BUG_ON(ret);
-
-                free_extent_buffer(dirty->root->node);
-                kfree(dirty->root);
-                kfree(dirty);
-
                 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;
 }
 
@@ -839,24 +708,23 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         if (ret)
                 goto fail;
 
-        btrfs_record_root_in_trans(root);
+        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));
 
         key.objectid = objectid;
-        key.offset = trans->transid;
+        key.offset = 0;
         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 
         old = btrfs_lock_root_node(root);
         btrfs_cow_block(trans, root, old, NULL, 0, &old);
+        btrfs_set_lock_blocking(old);
 
         btrfs_copy_root(trans, root, old, &tmp, objectid);
         btrfs_tree_unlock(old);
         free_extent_buffer(old);
 
-        btrfs_set_root_bytenr(new_root_item, tmp->start);
-        btrfs_set_root_level(new_root_item, btrfs_header_level(tmp));
-        btrfs_set_root_generation(new_root_item, trans->transid);
+        btrfs_set_root_node(new_root_item, tmp);
         ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
                                 new_root_item);
         btrfs_tree_unlock(tmp);
@@ -964,6 +832,24 @@ static noinline int finish_pending_snapshots(struct btrfs_trans_handle *trans,
         return 0;
 }
 
+static void update_super_roots(struct btrfs_root *root)
+{
+        struct btrfs_root_item *root_item;
+        struct btrfs_super_block *super;
+
+        super = &root->fs_info->super_copy;
+
+        root_item = &root->fs_info->chunk_root->root_item;
+        super->chunk_root = root_item->bytenr;
+        super->chunk_root_generation = root_item->generation;
+        super->chunk_root_level = root_item->level;
+
+        root_item = &root->fs_info->tree_root->root_item;
+        super->root = root_item->bytenr;
+        super->generation = root_item->generation;
+        super->root_level = root_item->level;
+}
+
 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                              struct btrfs_root *root)
 {
@@ -971,8 +857,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
         unsigned long timeout = 1;
         struct btrfs_transaction *cur_trans;
         struct btrfs_transaction *prev_trans = NULL;
-        struct btrfs_root *chunk_root = root->fs_info->chunk_root;
-        struct list_head dirty_fs_roots;
         struct extent_io_tree *pinned_copy;
         DEFINE_WAIT(wait);
         int ret;
@@ -999,7 +883,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
         BUG_ON(ret);
 
         mutex_lock(&root->fs_info->trans_mutex);
-        INIT_LIST_HEAD(&dirty_fs_roots);
         if (cur_trans->in_commit) {
                 cur_trans->use_count++;
                 mutex_unlock(&root->fs_info->trans_mutex);
@@ -1105,41 +988,36 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
          * with the tree-log code.
          */
         mutex_lock(&root->fs_info->tree_log_mutex);
-        /*
-         * keep tree reloc code from adding new reloc trees
-         */
-        mutex_lock(&root->fs_info->tree_reloc_mutex);
-
 
-        ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
-                              &dirty_fs_roots);
+        ret = commit_fs_roots(trans, root);
         BUG_ON(ret);
 
-        /* add_dirty_roots gets rid of all the tree log roots, it is now
+        /* commit_fs_roots gets rid of all the tree log roots, it is now
          * safe to free the root of tree log roots
          */
         btrfs_free_log_root_tree(trans, root->fs_info);
 
-        ret = btrfs_commit_tree_roots(trans, root);
+        ret = commit_cowonly_roots(trans, root);
         BUG_ON(ret);
 
         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_super_generation(&root->fs_info->super_copy,
-                                   cur_trans->transid);
-        btrfs_set_super_root(&root->fs_info->super_copy,
-                             root->fs_info->tree_root->node->start);
-        btrfs_set_super_root_level(&root->fs_info->super_copy,
-                           btrfs_header_level(root->fs_info->tree_root->node));
-
-        btrfs_set_super_chunk_root(&root->fs_info->super_copy,
-                                   chunk_root->node->start);
-        btrfs_set_super_chunk_root_level(&root->fs_info->super_copy,
-                                         btrfs_header_level(chunk_root->node));
-        btrfs_set_super_chunk_root_generation(&root->fs_info->super_copy,
-                                btrfs_header_generation(chunk_root->node));
+
+        btrfs_set_root_node(&root->fs_info->tree_root->root_item,
+                            root->fs_info->tree_root->node);
+        free_extent_buffer(root->fs_info->tree_root->commit_root);
+        root->fs_info->tree_root->commit_root =
+                                btrfs_root_node(root->fs_info->tree_root);
+
+        btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
+                            root->fs_info->chunk_root->node);
+        free_extent_buffer(root->fs_info->chunk_root->commit_root);
+        root->fs_info->chunk_root->commit_root =
+                                btrfs_root_node(root->fs_info->chunk_root);
+
+        update_super_roots(root);
 
         if (!root->fs_info->log_root_recovering) {
                 btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
@@ -1153,7 +1031,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 
         trans->transaction->blocked = 0;
 
-        wake_up(&root->fs_info->transaction_throttle);
         wake_up(&root->fs_info->transaction_wait);
 
         mutex_unlock(&root->fs_info->trans_mutex);
@@ -1170,9 +1047,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
         btrfs_finish_extent_commit(trans, root, pinned_copy);
         kfree(pinned_copy);
 
-        btrfs_drop_dead_reloc_roots(root);
-        mutex_unlock(&root->fs_info->tree_reloc_mutex);
-
         /* do the directory inserts of any pending snapshot creations */
         finish_pending_snapshots(trans, root->fs_info);
 
@@ -1186,16 +1060,9 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
         put_transaction(cur_trans);
         put_transaction(cur_trans);
 
-        list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
-        if (root->fs_info->closing)
-                list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
-
         mutex_unlock(&root->fs_info->trans_mutex);
 
         kmem_cache_free(btrfs_trans_handle_cachep, trans);
-
-        if (root->fs_info->closing)
-                drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
         return ret;
 }
 
@@ -1204,16 +1071,17 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
  */
 int btrfs_clean_old_snapshots(struct btrfs_root *root)
 {
-        struct list_head dirty_roots;
-        INIT_LIST_HEAD(&dirty_roots);
-again:
-        mutex_lock(&root->fs_info->trans_mutex);
-        list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
-        mutex_unlock(&root->fs_info->trans_mutex);
+        LIST_HEAD(list);
+        struct btrfs_fs_info *fs_info = root->fs_info;
+
+        mutex_lock(&fs_info->trans_mutex);
+        list_splice_init(&fs_info->dead_roots, &list);
+        mutex_unlock(&fs_info->trans_mutex);
 
-        if (!list_empty(&dirty_roots)) {
-                drop_dirty_roots(root, &dirty_roots);
-                goto again;
+        while (!list_empty(&list)) {
+                root = list_entry(list.next, struct btrfs_root, root_list);
+                list_del_init(&root->root_list);
+                btrfs_drop_dead_root(root);
         }
         return 0;
 }