diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 80953528572db52af07ceae9ec782b284ab29610..68f322f600a0677813867c5278b5aca9c23a6e8f 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3163,6 +3163,9 @@ void btrfs_destroy_inode(struct inode *inode);
 int btrfs_drop_inode(struct inode *inode);
 int __init btrfs_init_cachep(void);
 void __cold btrfs_destroy_cachep(void);
+struct inode *btrfs_iget_path(struct super_block *s, struct btrfs_key *location,
+			      struct btrfs_root *root, int *new,
+			      struct btrfs_path *path);
 struct inode *btrfs_iget(struct super_block *s, struct btrfs_key *location,
 			 struct btrfs_root *root, int *was_new);
 struct extent_map *btrfs_get_extent(struct btrfs_inode *inode,
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index b0ab41da91d122b8cd8c8010cd56973af2afd240..3f0b6d1936e8ecd05dc0bf4957bb6aa691204dd4 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1664,9 +1664,8 @@ static int cleaner_kthread(void *arg)
 	struct btrfs_root *root = arg;
 	struct btrfs_fs_info *fs_info = root->fs_info;
 	int again;
-	struct btrfs_trans_handle *trans;
 
-	do {
+	while (1) {
 		again = 0;
 
 		/* Make the cleaner go to sleep early. */
@@ -1715,42 +1714,16 @@ static int cleaner_kthread(void *arg)
 		 */
 		btrfs_delete_unused_bgs(fs_info);
 sleep:
+		if (kthread_should_park())
+			kthread_parkme();
+		if (kthread_should_stop())
+			return 0;
 		if (!again) {
 			set_current_state(TASK_INTERRUPTIBLE);
-			if (!kthread_should_stop())
-				schedule();
+			schedule();
 			__set_current_state(TASK_RUNNING);
 		}
-	} while (!kthread_should_stop());
-
-	/*
-	 * Transaction kthread is stopped before us and wakes us up.
-	 * However we might have started a new transaction and COWed some
-	 * tree blocks when deleting unused block groups for example. So
-	 * make sure we commit the transaction we started to have a clean
-	 * shutdown when evicting the btree inode - if it has dirty pages
-	 * when we do the final iput() on it, eviction will trigger a
-	 * writeback for it which will fail with null pointer dereferences
-	 * since work queues and other resources were already released and
-	 * destroyed by the time the iput/eviction/writeback is made.
-	 */
-	trans = btrfs_attach_transaction(root);
-	if (IS_ERR(trans)) {
-		if (PTR_ERR(trans) != -ENOENT)
-			btrfs_err(fs_info,
-				  "cleaner transaction attach returned %ld",
-				  PTR_ERR(trans));
-	} else {
-		int ret;
-
-		ret = btrfs_commit_transaction(trans);
-		if (ret)
-			btrfs_err(fs_info,
-				  "cleaner open transaction commit returned %d",
-				  ret);
 	}
-
-	return 0;
 }
 
 static int transaction_kthread(void *arg)
@@ -3931,6 +3904,13 @@ void close_ctree(struct btrfs_fs_info *fs_info)
 	int ret;
 
 	set_bit(BTRFS_FS_CLOSING_START, &fs_info->flags);
+	/*
+	 * We don't want the cleaner to start new transactions, add more delayed
+	 * iputs, etc. while we're closing. We can't use kthread_stop() yet
+	 * because that frees the task_struct, and the transaction kthread might
+	 * still try to wake up the cleaner.
+	 */
+	kthread_park(fs_info->cleaner_kthread);
 
 	/* wait for the qgroup rescan worker to stop */
 	btrfs_qgroup_wait_for_completion(fs_info, false);
@@ -3958,9 +3938,8 @@ void close_ctree(struct btrfs_fs_info *fs_info)
 
 	if (!sb_rdonly(fs_info->sb)) {
 		/*
-		 * If the cleaner thread is stopped and there are
-		 * block groups queued for removal, the deletion will be
-		 * skipped when we quit the cleaner thread.
+		 * The cleaner kthread is stopped, so do one final pass over
+		 * unused block groups.
 		 */
 		btrfs_delete_unused_bgs(fs_info);
 
@@ -4359,13 +4338,23 @@ static int btrfs_destroy_pinned_extent(struct btrfs_fs_info *fs_info,
 	unpin = pinned_extents;
 again:
 	while (1) {
+		/*
+		 * The btrfs_finish_extent_commit() may get the same range as
+		 * ours between find_first_extent_bit and clear_extent_dirty.
+		 * Hence, hold the unused_bg_unpin_mutex to avoid double unpin
+		 * the same extent range.
+		 */
+		mutex_lock(&fs_info->unused_bg_unpin_mutex);
 		ret = find_first_extent_bit(unpin, 0, &start, &end,
 					    EXTENT_DIRTY, NULL);
-		if (ret)
+		if (ret) {
+			mutex_unlock(&fs_info->unused_bg_unpin_mutex);
 			break;
+		}
 
 		clear_extent_dirty(unpin, start, end);
 		btrfs_error_unpin_extent_range(fs_info, start, end);
+		mutex_unlock(&fs_info->unused_bg_unpin_mutex);
 		cond_resched();
 	}
 
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 4ba0aedc878bd4422e67d47879b1de297ed848c8..74aa552f47930699aa2a81134c3200bf2f5d5c5e 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -75,7 +75,8 @@ static struct inode *__lookup_free_space_inode(struct btrfs_root *root,
 	 * sure NOFS is set to keep us from deadlocking.
 	 */
 	nofs_flag = memalloc_nofs_save();
-	inode = btrfs_iget(fs_info->sb, &location, root, NULL);
+	inode = btrfs_iget_path(fs_info->sb, &location, root, NULL, path);
+	btrfs_release_path(path);
 	memalloc_nofs_restore(nofs_flag);
 	if (IS_ERR(inode))
 		return inode;
@@ -838,6 +839,25 @@ int load_free_space_cache(struct btrfs_fs_info *fs_info,
 	path->search_commit_root = 1;
 	path->skip_locking = 1;
 
+	/*
+	 * We must pass a path with search_commit_root set to btrfs_iget in
+	 * order to avoid a deadlock when allocating extents for the tree root.
+	 *
+	 * When we are COWing an extent buffer from the tree root, when looking
+	 * for a free extent, at extent-tree.c:find_free_extent(), we can find
+	 * block group without its free space cache loaded. When we find one
+	 * we must load its space cache which requires reading its free space
+	 * cache's inode item from the root tree. If this inode item is located
+	 * in the same leaf that we started COWing before, then we end up in
+	 * deadlock on the extent buffer (trying to read lock it when we
+	 * previously write locked it).
+	 *
+	 * It's safe to read the inode item using the commit root because
+	 * block groups, once loaded, stay in memory forever (until they are
+	 * removed) as well as their space caches once loaded. New block groups
+	 * once created get their ->cached field set to BTRFS_CACHE_FINISHED so
+	 * we will never try to read their inode item while the fs is mounted.
+	 */
 	inode = lookup_free_space_inode(fs_info, block_group, path);
 	if (IS_ERR(inode)) {
 		btrfs_free_path(path);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index d3df5b52278cea06c05384ef7bf63aaed6b5404f..9ea4c6f0352f06e828a400890c50122c7ec33ee5 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1531,12 +1531,11 @@ static noinline int run_delalloc_nocow(struct inode *inode,
 	}
 	btrfs_release_path(path);
 
-	if (cur_offset <= end && cow_start == (u64)-1) {
+	if (cur_offset <= end && cow_start == (u64)-1)
 		cow_start = cur_offset;
-		cur_offset = end;
-	}
 
 	if (cow_start != (u64)-1) {
+		cur_offset = end;
 		ret = cow_file_range(inode, locked_page, cow_start, end, end,
 				     page_started, nr_written, 1, NULL);
 		if (ret)
@@ -3570,10 +3569,11 @@ static noinline int acls_after_inode_item(struct extent_buffer *leaf,
 /*
  * read an inode from the btree into the in-memory inode
  */
-static int btrfs_read_locked_inode(struct inode *inode)
+static int btrfs_read_locked_inode(struct inode *inode,
+				   struct btrfs_path *in_path)
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
-	struct btrfs_path *path;
+	struct btrfs_path *path = in_path;
 	struct extent_buffer *leaf;
 	struct btrfs_inode_item *inode_item;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
@@ -3589,15 +3589,18 @@ static int btrfs_read_locked_inode(struct inode *inode)
 	if (!ret)
 		filled = true;
 
-	path = btrfs_alloc_path();
-	if (!path)
-		return -ENOMEM;
+	if (!path) {
+		path = btrfs_alloc_path();
+		if (!path)
+			return -ENOMEM;
+	}
 
 	memcpy(&location, &BTRFS_I(inode)->location, sizeof(location));
 
 	ret = btrfs_lookup_inode(NULL, root, path, &location, 0);
 	if (ret) {
-		btrfs_free_path(path);
+		if (path != in_path)
+			btrfs_free_path(path);
 		return ret;
 	}
 
@@ -3722,7 +3725,8 @@ static int btrfs_read_locked_inode(struct inode *inode)
 				  btrfs_ino(BTRFS_I(inode)),
 				  root->root_key.objectid, ret);
 	}
-	btrfs_free_path(path);
+	if (path != in_path)
+		btrfs_free_path(path);
 
 	if (!maybe_acls)
 		cache_no_acl(inode);
@@ -5644,8 +5648,9 @@ static struct inode *btrfs_iget_locked(struct super_block *s,
 /* Get an inode object given its location and corresponding root.
  * Returns in *is_new if the inode was read from disk
  */
-struct inode *btrfs_iget(struct super_block *s, struct btrfs_key *location,
-			 struct btrfs_root *root, int *new)
+struct inode *btrfs_iget_path(struct super_block *s, struct btrfs_key *location,
+			      struct btrfs_root *root, int *new,
+			      struct btrfs_path *path)
 {
 	struct inode *inode;
 
@@ -5656,7 +5661,7 @@ struct inode *btrfs_iget(struct super_block *s, struct btrfs_key *location,
 	if (inode->i_state & I_NEW) {
 		int ret;
 
-		ret = btrfs_read_locked_inode(inode);
+		ret = btrfs_read_locked_inode(inode, path);
 		if (!ret) {
 			inode_tree_add(inode);
 			unlock_new_inode(inode);
@@ -5678,6 +5683,12 @@ struct inode *btrfs_iget(struct super_block *s, struct btrfs_key *location,
 	return inode;
 }
 
+struct inode *btrfs_iget(struct super_block *s, struct btrfs_key *location,
+			 struct btrfs_root *root, int *new)
+{
+	return btrfs_iget_path(s, location, root, new, NULL);
+}
+
 static struct inode *new_simple_dir(struct super_block *s,
 				    struct btrfs_key *key,
 				    struct btrfs_root *root)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 3ca6943827ef88e536b2d6c924e7664a3ab835e7..802a628e9f7d7fe629a76e8d108b75c04ed4246e 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3488,6 +3488,8 @@ static int btrfs_extent_same_range(struct inode *src, u64 loff, u64 olen,
 			const u64 sz = BTRFS_I(src)->root->fs_info->sectorsize;
 
 			len = round_down(i_size_read(src), sz) - loff;
+			if (len == 0)
+				return 0;
 			olen = len;
 		}
 	}
@@ -4257,9 +4259,17 @@ static noinline int btrfs_clone_files(struct file *file, struct file *file_src,
 		goto out_unlock;
 	if (len == 0)
 		olen = len = src->i_size - off;
-	/* if we extend to eof, continue to block boundary */
-	if (off + len == src->i_size)
+	/*
+	 * If we extend to eof, continue to block boundary if and only if the
+	 * destination end offset matches the destination file's size, otherwise
+	 * we would be corrupting data by placing the eof block into the middle
+	 * of a file.
+	 */
+	if (off + len == src->i_size) {
+		if (!IS_ALIGNED(len, bs) && destoff + len < inode->i_size)
+			goto out_unlock;
 		len = ALIGN(src->i_size, bs) - off;
+	}
 
 	if (len == 0) {
 		ret = 0;
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index b362b45dd7578ff2517baf86ac8779a211aba098..cbc9d0d2c12de42786da57c41ebbc9f0364ffabd 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1916,7 +1916,7 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 }
 
 /* Used to sort the devices by max_avail(descending sort) */
-static int btrfs_cmp_device_free_bytes(const void *dev_info1,
+static inline int btrfs_cmp_device_free_bytes(const void *dev_info1,
 				       const void *dev_info2)
 {
 	if (((struct btrfs_device_info *)dev_info1)->max_avail >
@@ -1945,8 +1945,8 @@ static inline void btrfs_descending_sort_devices(
  * The helper to calc the free space on the devices that can be used to store
  * file data.
  */
-static int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
-				       u64 *free_bytes)
+static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
+					      u64 *free_bytes)
 {
 	struct btrfs_device_info *devices_info;
 	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index cab0b1f1f741797c32b8d399194554642ecf8a64..efcf89a8ba44c3300f1a214f01ed935ce933c188 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -440,7 +440,7 @@ static int check_block_group_item(struct btrfs_fs_info *fs_info,
 	    type != (BTRFS_BLOCK_GROUP_METADATA |
 			   BTRFS_BLOCK_GROUP_DATA)) {
 		block_group_err(fs_info, leaf, slot,
-"invalid type, have 0x%llx (%lu bits set) expect either 0x%llx, 0x%llx, 0x%llu or 0x%llx",
+"invalid type, have 0x%llx (%lu bits set) expect either 0x%llx, 0x%llx, 0x%llx or 0x%llx",
 			type, hweight64(type),
 			BTRFS_BLOCK_GROUP_DATA, BTRFS_BLOCK_GROUP_METADATA,
 			BTRFS_BLOCK_GROUP_SYSTEM,
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index e07f3376b7dfc0c9350117bf3db956781e57d45e..a5ce99a6c936558f820d94a63d1301a111f8486b 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -4396,6 +4396,23 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
 	logged_end = end;
 
 	list_for_each_entry_safe(em, n, &tree->modified_extents, list) {
+		/*
+		 * Skip extents outside our logging range. It's important to do
+		 * it for correctness because if we don't ignore them, we may
+		 * log them before their ordered extent completes, and therefore
+		 * we could log them without logging their respective checksums
+		 * (the checksum items are added to the csum tree at the very
+		 * end of btrfs_finish_ordered_io()). Also leave such extents
+		 * outside of our range in the list, since we may have another
+		 * ranged fsync in the near future that needs them. If an extent
+		 * outside our range corresponds to a hole, log it to avoid
+		 * leaving gaps between extents (fsck will complain when we are
+		 * not using the NO_HOLES feature).
+		 */
+		if ((em->start > end || em->start + em->len <= start) &&
+		    em->block_start != EXTENT_MAP_HOLE)
+			continue;
+
 		list_del_init(&em->list);
 		/*
 		 * Just an arbitrary number, this can be really CPU intensive