diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 8fe4eb7e5045..27e5b269e729 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1591,7 +1591,6 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct page **pages = NULL;
-	struct extent_state *cached_state = NULL;
 	struct extent_changeset *data_reserved = NULL;
 	u64 release_bytes = 0;
 	u64 lockstart;
@@ -1611,6 +1610,7 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
 		return -ENOMEM;
 
 	while (iov_iter_count(i) > 0) {
+		struct extent_state *cached_state = NULL;
 		size_t offset = offset_in_page(pos);
 		size_t sector_offset;
 		size_t write_bytes = min(iov_iter_count(i),
@@ -1758,9 +1758,20 @@ again:
 		if (copied > 0)
 			ret = btrfs_dirty_pages(inode, pages, dirty_pages,
 						pos, copied, &cached_state);
+
+		/*
+		 * If we have not locked the extent range, because the range's
+		 * start offset is >= i_size, we might still have a non-NULL
+		 * cached extent state, acquired while marking the extent range
+		 * as delalloc through btrfs_dirty_pages(). Therefore free any
+		 * possible cached extent state to avoid a memory leak.
+		 */
 		if (extents_locked)
 			unlock_extent_cached(&BTRFS_I(inode)->io_tree,
 					     lockstart, lockend, &cached_state);
+		else
+			free_extent_state(cached_state);
+
 		btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes,
 					       true);
 		if (ret) {
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index a0546401bc0a..0f2754eaa05b 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6305,13 +6305,16 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
 	u32 sizes[2];
 	int nitems = name ? 2 : 1;
 	unsigned long ptr;
+	unsigned int nofs_flag;
 	int ret;
 
 	path = btrfs_alloc_path();
 	if (!path)
 		return ERR_PTR(-ENOMEM);
 
+	nofs_flag = memalloc_nofs_save();
 	inode = new_inode(fs_info->sb);
+	memalloc_nofs_restore(nofs_flag);
 	if (!inode) {
 		btrfs_free_path(path);
 		return ERR_PTR(-ENOMEM);
diff --git a/fs/btrfs/ref-verify.c b/fs/btrfs/ref-verify.c
index e87cbdad02a3..b57f3618e58e 100644
--- a/fs/btrfs/ref-verify.c
+++ b/fs/btrfs/ref-verify.c
@@ -500,7 +500,7 @@ static int process_leaf(struct btrfs_root *root,
 	struct btrfs_extent_data_ref *dref;
 	struct btrfs_shared_data_ref *sref;
 	u32 count;
-	int i = 0, tree_block_level = 0, ret;
+	int i = 0, tree_block_level = 0, ret = 0;
 	struct btrfs_key key;
 	int nritems = btrfs_header_nritems(leaf);
 
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index f3215028235c..123ac54af071 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -5085,7 +5085,7 @@ static int clone_range(struct send_ctx *sctx,
 	struct btrfs_path *path;
 	struct btrfs_key key;
 	int ret;
-	u64 clone_src_i_size;
+	u64 clone_src_i_size = 0;
 
 	/*
 	 * Prevent cloning from a zero offset with a length matching the sector
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 29b82a795522..8a6cc600bf18 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2932,7 +2932,8 @@ out:
  * in the tree of log roots
  */
 static int update_log_root(struct btrfs_trans_handle *trans,
-			   struct btrfs_root *log)
+			   struct btrfs_root *log,
+			   struct btrfs_root_item *root_item)
 {
 	struct btrfs_fs_info *fs_info = log->fs_info;
 	int ret;
@@ -2940,10 +2941,10 @@ static int update_log_root(struct btrfs_trans_handle *trans,
 	if (log->log_transid == 1) {
 		/* insert root item on the first sync */
 		ret = btrfs_insert_root(trans, fs_info->log_root_tree,
-				&log->root_key, &log->root_item);
+				&log->root_key, root_item);
 	} else {
 		ret = btrfs_update_root(trans, fs_info->log_root_tree,
-				&log->root_key, &log->root_item);
+				&log->root_key, root_item);
 	}
 	return ret;
 }
@@ -3041,6 +3042,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 	struct btrfs_fs_info *fs_info = root->fs_info;
 	struct btrfs_root *log = root->log_root;
 	struct btrfs_root *log_root_tree = fs_info->log_root_tree;
+	struct btrfs_root_item new_root_item;
 	int log_transid = 0;
 	struct btrfs_log_ctx root_log_ctx;
 	struct blk_plug plug;
@@ -3104,17 +3106,25 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 		goto out;
 	}
 
+	/*
+	 * We _must_ update under the root->log_mutex in order to make sure we
+	 * have a consistent view of the log root we are trying to commit at
+	 * this moment.
+	 *
+	 * We _must_ copy this into a local copy, because we are not holding the
+	 * log_root_tree->log_mutex yet.  This is important because when we
+	 * commit the log_root_tree we must have a consistent view of the
+	 * log_root_tree when we update the super block to point at the
+	 * log_root_tree bytenr.  If we update the log_root_tree here we'll race
+	 * with the commit and possibly point at the new block which we may not
+	 * have written out.
+	 */
 	btrfs_set_root_node(&log->root_item, log->node);
+	memcpy(&new_root_item, &log->root_item, sizeof(new_root_item));
 
 	root->log_transid++;
 	log->log_transid = root->log_transid;
 	root->log_start_pid = 0;
-	/*
-	 * Update or create log root item under the root's log_mutex to prevent
-	 * races with concurrent log syncs that can lead to failure to update
-	 * log root item because it was not created yet.
-	 */
-	ret = update_log_root(trans, log);
 	/*
 	 * IO has been started, blocks of the log tree have WRITTEN flag set
 	 * in their headers. new modifications of the log will be written to
@@ -3135,6 +3145,14 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 	mutex_unlock(&log_root_tree->log_mutex);
 
 	mutex_lock(&log_root_tree->log_mutex);
+
+	/*
+	 * Now we are safe to update the log_root_tree because we're under the
+	 * log_mutex, and we're a current writer so we're holding the commit
+	 * open until we drop the log_mutex.
+	 */
+	ret = update_log_root(trans, log, &new_root_item);
+
 	if (atomic_dec_and_test(&log_root_tree->log_writers)) {
 		/* atomic_dec_and_test implies a barrier */
 		cond_wake_up_nomb(&log_root_tree->log_writer_wait);
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index cdd7af424033..bdfe4493e43a 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3845,7 +3845,11 @@ static int alloc_profile_is_valid(u64 flags, int extended)
 		return !extended; /* "0" is valid for usual profiles */
 
 	/* true if exactly one bit set */
-	return is_power_of_2(flags);
+	/*
+	 * Don't use is_power_of_2(unsigned long) because it won't work
+	 * for the single profile (1ULL << 48) on 32-bit CPUs.
+	 */
+	return flags != 0 && (flags & (flags - 1)) == 0;
 }
 
 static inline int balance_need_close(struct btrfs_fs_info *fs_info)