1 files changed, 43 insertions, 15 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 32312e09f0f5..c6b6a6e3e735 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -549,7 +549,7 @@ static int cache_block_group(struct btrfs_block_group_cache *cache,
         caching_ctl->block_group = cache;
         caching_ctl->progress = cache->key.objectid;
         atomic_set(&caching_ctl->count, 1);
-        caching_ctl->work.func = caching_thread;
+        btrfs_init_work(&caching_ctl->work, caching_thread, NULL, NULL);
 
         spin_lock(&cache->lock);
         /*
@@ -640,7 +640,7 @@ static int cache_block_group(struct btrfs_block_group_cache *cache,
 
         btrfs_get_block_group(cache);
 
-        btrfs_queue_worker(&fs_info->caching_workers, &caching_ctl->work);
+        btrfs_queue_work(fs_info->caching_workers, &caching_ctl->work);
 
         return ret;
 }
@@ -3971,7 +3971,7 @@ static int can_overcommit(struct btrfs_root *root,
 }
 
 static void btrfs_writeback_inodes_sb_nr(struct btrfs_root *root,
-                                         unsigned long nr_pages)
+                                         unsigned long nr_pages, int nr_items)
 {
         struct super_block *sb = root->fs_info->sb;
 
@@ -3986,9 +3986,9 @@ static void btrfs_writeback_inodes_sb_nr(struct btrfs_root *root,
                  * the filesystem is readonly(all dirty pages are written to
                  * the disk).
                  */
-                btrfs_start_delalloc_roots(root->fs_info, 0);
+                btrfs_start_delalloc_roots(root->fs_info, 0, nr_items);
                 if (!current->journal_info)
-                        btrfs_wait_ordered_roots(root->fs_info, -1);
+                        btrfs_wait_ordered_roots(root->fs_info, nr_items);
         }
 }
 
@@ -4045,7 +4045,7 @@ static void shrink_delalloc(struct btrfs_root *root, u64 to_reclaim, u64 orig,
         while (delalloc_bytes && loops < 3) {
                 max_reclaim = min(delalloc_bytes, to_reclaim);
                 nr_pages = max_reclaim >> PAGE_CACHE_SHIFT;
-                btrfs_writeback_inodes_sb_nr(root, nr_pages);
+                btrfs_writeback_inodes_sb_nr(root, nr_pages, items);
                 /*
                  * We need to wait for the async pages to actually start before
                  * we do anything.
@@ -4112,13 +4112,9 @@ static int may_commit_transaction(struct btrfs_root *root,
                 goto commit;
 
         /* See if there is enough pinned space to make this reservation */
-        spin_lock(&space_info->lock);
         if (percpu_counter_compare(&space_info->total_bytes_pinned,
-                                   bytes) >= 0) {
-                spin_unlock(&space_info->lock);
+                                   bytes) >= 0)
                 goto commit;
-        }
-        spin_unlock(&space_info->lock);
 
         /*
          * See if there is some space in the delayed insertion reservation for
@@ -4127,16 +4123,13 @@ static int may_commit_transaction(struct btrfs_root *root,
         if (space_info != delayed_rsv->space_info)
                 return -ENOSPC;
 
-        spin_lock(&space_info->lock);
         spin_lock(&delayed_rsv->lock);
         if (percpu_counter_compare(&space_info->total_bytes_pinned,
                                    bytes - delayed_rsv->size) >= 0) {
                 spin_unlock(&delayed_rsv->lock);
-                spin_unlock(&space_info->lock);
                 return -ENOSPC;
         }
         spin_unlock(&delayed_rsv->lock);
-        spin_unlock(&space_info->lock);
 
 commit:
         trans = btrfs_join_transaction(root);
@@ -4181,7 +4174,7 @@ static int flush_space(struct btrfs_root *root,
                 break;
         case FLUSH_DELALLOC:
         case FLUSH_DELALLOC_WAIT:
-                shrink_delalloc(root, num_bytes, orig_bytes,
+                shrink_delalloc(root, num_bytes * 2, orig_bytes,
                                 state == FLUSH_DELALLOC_WAIT);
                 break;
         case ALLOC_CHUNK:
@@ -8938,3 +8931,38 @@ int btrfs_trim_fs(struct btrfs_root *root, struct fstrim_range *range)
         range->len = trimmed;
         return ret;
 }
+
+/*
+ * btrfs_{start,end}_write() is similar to mnt_{want, drop}_write(),
+ * they are used to prevent the some tasks writing data into the page cache
+ * by nocow before the subvolume is snapshoted, but flush the data into
+ * the disk after the snapshot creation.
+ */
+void btrfs_end_nocow_write(struct btrfs_root *root)
+{
+        percpu_counter_dec(&root->subv_writers->counter);
+        /*
+         * Make sure counter is updated before we wake up
+         * waiters.
+         */
+        smp_mb();
+        if (waitqueue_active(&root->subv_writers->wait))
+                wake_up(&root->subv_writers->wait);
+}
+
+int btrfs_start_nocow_write(struct btrfs_root *root)
+{
+        if (unlikely(atomic_read(&root->will_be_snapshoted)))
+                return 0;
+
+        percpu_counter_inc(&root->subv_writers->counter);
+        /*
+         * Make sure counter is updated before we check for snapshot creation.
+         */
+        smp_mb();
+        if (unlikely(atomic_read(&root->will_be_snapshoted))) {
+                btrfs_end_nocow_write(root);
+                return 0;
+        }
+        return 1;
+}