btrfs: add wrapper for transaction abort predicate

The status of aborted transaction can change between calls and it needs
to be accessed by READ_ONCE. Add a helper that also wraps the unlikely
hint.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/block-group.c

@@ -2345,7 +2345,7 @@ static int cache_save_setup(struct btrfs_block_group *block_group,
 		return 0;
 	}
 
-	if (trans->aborted)
+	if (TRANS_ABORTED(trans))
 		return 0;
 again:
 	inode = lookup_free_space_inode(block_group, path);

fs/btrfs/delayed-inode.c

@@ -1139,7 +1139,7 @@ static int __btrfs_run_delayed_items(struct btrfs_trans_handle *trans, int nr)
 	int ret = 0;
 	bool count = (nr > 0);
 
-	if (trans->aborted)
+	if (TRANS_ABORTED(trans))
 		return -EIO;
 
 	path = btrfs_alloc_path();

fs/btrfs/extent-tree.c

@@ -1583,7 +1583,7 @@ static int run_delayed_extent_op(struct btrfs_trans_handle *trans,
 	int err = 0;
 	int metadata = !extent_op->is_data;
 
-	if (trans->aborted)
+	if (TRANS_ABORTED(trans))
 		return 0;
 
 	if (metadata && !btrfs_fs_incompat(fs_info, SKINNY_METADATA))
@@ -1703,7 +1703,7 @@ static int run_one_delayed_ref(struct btrfs_trans_handle *trans,
 {
 	int ret = 0;
 
-	if (trans->aborted) {
+	if (TRANS_ABORTED(trans)) {
 		if (insert_reserved)
 			btrfs_pin_extent(trans->fs_info, node->bytenr,
 					 node->num_bytes, 1);
@@ -2191,7 +2191,7 @@ int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
 	int run_all = count == (unsigned long)-1;
 
 	/* We'll clean this up in btrfs_cleanup_transaction */
-	if (trans->aborted)
+	if (TRANS_ABORTED(trans))
 		return 0;
 
 	if (test_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags))
@@ -2913,7 +2913,7 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans)
 	else
 		unpin = &fs_info->freed_extents[0];
 
-	while (!trans->aborted) {
+	while (!TRANS_ABORTED(trans)) {
 		struct extent_state *cached_state = NULL;
 
 		mutex_lock(&fs_info->unused_bg_unpin_mutex);
@@ -2950,7 +2950,7 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans)
 		u64 trimmed = 0;
 
 		ret = -EROFS;
-		if (!trans->aborted)
+		if (!TRANS_ABORTED(trans))
 			ret = btrfs_discard_extent(fs_info,
 						   block_group->start,
 						   block_group->length,

fs/btrfs/super.c

@@ -244,7 +244,7 @@ void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
 {
 	struct btrfs_fs_info *fs_info = trans->fs_info;
 
-	trans->aborted = errno;
+	WRITE_ONCE(trans->aborted, errno);
 	/* Nothing used. The other threads that have joined this
 	 * transaction may be able to continue. */
 	if (!trans->dirty && list_empty(&trans->new_bgs)) {

fs/btrfs/transaction.c

@@ -243,7 +243,7 @@ static noinline int join_transaction(struct btrfs_fs_info *fs_info,
 
 	cur_trans = fs_info->running_transaction;
 	if (cur_trans) {
-		if (cur_trans->aborted) {
+		if (TRANS_ABORTED(cur_trans)) {
 			spin_unlock(&fs_info->trans_lock);
 			return cur_trans->aborted;
 		}
@@ -459,7 +459,7 @@ static inline int is_transaction_blocked(struct btrfs_transaction *trans)
 {
 	return (trans->state >= TRANS_STATE_COMMIT_START &&
 		trans->state < TRANS_STATE_UNBLOCKED &&
-		!trans->aborted);
+		!TRANS_ABORTED(trans));
 }
 
 /* wait for commit against the current transaction to become unblocked
@@ -478,7 +478,7 @@ static void wait_current_trans(struct btrfs_fs_info *fs_info)
 
 		wait_event(fs_info->transaction_wait,
 			   cur_trans->state >= TRANS_STATE_UNBLOCKED ||
-			   cur_trans->aborted);
+			   TRANS_ABORTED(cur_trans));
 		btrfs_put_transaction(cur_trans);
 	} else {
 		spin_unlock(&fs_info->trans_lock);
@@ -937,7 +937,7 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 	if (throttle)
 		btrfs_run_delayed_iputs(info);
 
-	if (trans->aborted ||
+	if (TRANS_ABORTED(trans) ||
 	    test_bit(BTRFS_FS_STATE_ERROR, &info->fs_state)) {
 		wake_up_process(info->transaction_kthread);
 		err = -EIO;
@@ -1794,7 +1794,8 @@ static void wait_current_trans_commit_start(struct btrfs_fs_info *fs_info,
 					    struct btrfs_transaction *trans)
 {
 	wait_event(fs_info->transaction_blocked_wait,
-		   trans->state >= TRANS_STATE_COMMIT_START || trans->aborted);
+		   trans->state >= TRANS_STATE_COMMIT_START ||
+		   TRANS_ABORTED(trans));
 }
 
 /*
@@ -1806,7 +1807,8 @@ static void wait_current_trans_commit_start_and_unblock(
 					struct btrfs_transaction *trans)
 {
 	wait_event(fs_info->transaction_wait,
-		   trans->state >= TRANS_STATE_UNBLOCKED || trans->aborted);
+		   trans->state >= TRANS_STATE_UNBLOCKED ||
+		   TRANS_ABORTED(trans));
 }
 
 /*
@@ -2026,7 +2028,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
 	trans->dirty = true;
 
 	/* Stop the commit early if ->aborted is set */
-	if (unlikely(READ_ONCE(cur_trans->aborted))) {
+	if (TRANS_ABORTED(cur_trans)) {
 		ret = cur_trans->aborted;
 		btrfs_end_transaction(trans);
 		return ret;
@@ -2100,7 +2102,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
 
 		wait_for_commit(cur_trans);
 
-		if (unlikely(cur_trans->aborted))
+		if (TRANS_ABORTED(cur_trans))
 			ret = cur_trans->aborted;
 
 		btrfs_put_transaction(cur_trans);
@@ -2119,7 +2121,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
 			spin_unlock(&fs_info->trans_lock);
 
 			wait_for_commit(prev_trans);
-			ret = prev_trans->aborted;
+			ret = READ_ONCE(prev_trans->aborted);
 
 			btrfs_put_transaction(prev_trans);
 			if (ret)
@@ -2173,8 +2175,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
 	wait_event(cur_trans->writer_wait,
 		   atomic_read(&cur_trans->num_writers) == 1);
 
-	/* ->aborted might be set after the previous check, so check it */
-	if (unlikely(READ_ONCE(cur_trans->aborted))) {
+	if (TRANS_ABORTED(cur_trans)) {
 		ret = cur_trans->aborted;
 		goto scrub_continue;
 	}
@@ -2292,7 +2293,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
 	 * The tasks which save the space cache and inode cache may also
 	 * update ->aborted, check it.
 	 */
-	if (unlikely(READ_ONCE(cur_trans->aborted))) {
+	if (TRANS_ABORTED(cur_trans)) {
 		ret = cur_trans->aborted;
 		mutex_unlock(&fs_info->tree_log_mutex);
 		mutex_unlock(&fs_info->reloc_mutex);

fs/btrfs/transaction.h

@@ -115,6 +115,10 @@ struct btrfs_trans_handle {
 	struct btrfs_block_rsv *orig_rsv;
 	refcount_t use_count;
 	unsigned int type;
+	/*
+	 * Error code of transaction abort, set outside of locks and must use
+	 * the READ_ONCE/WRITE_ONCE access
+	 */
 	short aborted;
 	bool adding_csums;
 	bool allocating_chunk;
@@ -126,6 +130,14 @@ struct btrfs_trans_handle {
 	struct list_head new_bgs;
 };
 
+/*
+ * The abort status can be changed between calls and is not protected by locks.
+ * This accepts btrfs_transaction and btrfs_trans_handle as types. Once it's
+ * set to a non-zero value it does not change, so the macro should be in checks
+ * but is not necessary for further reads of the value.
+ */
+#define TRANS_ABORTED(trans)		(unlikely(READ_ONCE((trans)->aborted)))
+
 struct btrfs_pending_snapshot {
 	struct dentry *dentry;
 	struct inode *dir;