Commit a83342aa authored by David Sterba's avatar David Sterba
Browse files

btrfs: add comments to barriers before waitqueue_active 



Reduce number of undocumented barriers out there.

Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 33a9eca7

fs/btrfs/compression.c

+3 −0
Original line number Diff line number Diff line
@@ -839,6 +839,9 @@ static void free_workspace(int type, struct list_head *workspace) 
	btrfs_compress_op[idx]->free_workspace(workspace);

	atomic_dec(alloc_workspace);

wake:

	/*

	 * Make sure counter is updated before we wake up waiters.

	 */

	smp_mb();

	if (waitqueue_active(workspace_wait))

		wake_up(workspace_wait);

fs/btrfs/extent-tree.c

+1 −2
Original line number Diff line number Diff line
@@ -10363,8 +10363,7 @@ void btrfs_end_write_no_snapshoting(struct btrfs_root *root) 
{

	percpu_counter_dec(&root->subv_writers->counter);

	/*

	 * Make sure counter is updated before we wake up

	 * waiters.

	 * Make sure counter is updated before we wake up waiters.

	 */

	smp_mb();

	if (waitqueue_active(&root->subv_writers->wait))

fs/btrfs/locking.c

+3 −0
Original line number Diff line number Diff line
@@ -280,6 +280,9 @@ void btrfs_tree_unlock(struct extent_buffer *eb) 
	if (blockers) {

		WARN_ON(atomic_read(&eb->spinning_writers));

		atomic_dec(&eb->blocking_writers);

		/*

		 * Make sure counter is updated before we wake up waiters.

		 */

		smp_mb();

		if (waitqueue_active(&eb->write_lock_wq))

			wake_up(&eb->write_lock_wq);

fs/btrfs/ordered-data.c

+6 −0
Original line number Diff line number Diff line
@@ -345,6 +345,9 @@ int btrfs_dec_test_first_ordered_pending(struct inode *inode, 


	if (entry->bytes_left == 0) {

		ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);

		/*

		 * Implicit memory barrier after test_and_set_bit

		 */

		if (waitqueue_active(&entry->wait))

			wake_up(&entry->wait);

	} else {
@@ -409,6 +412,9 @@ int btrfs_dec_test_ordered_pending(struct inode *inode, 


	if (entry->bytes_left == 0) {

		ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);

		/*

		 * Implicit memory barrier after test_and_set_bit

		 */

		if (waitqueue_active(&entry->wait))

			wake_up(&entry->wait);

	} else {

fs/btrfs/transaction.c

+3 −0
Original line number Diff line number Diff line
@@ -861,6 +861,9 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans, 
	atomic_dec(&cur_trans->num_writers);

	extwriter_counter_dec(cur_trans, trans->type);



	/*

	 * Make sure counter is updated before we wake up waiters.

	 */

	smp_mb();

	if (waitqueue_active(&cur_trans->writer_wait))

		wake_up(&cur_trans->writer_wait);