btrfs: tree-log: make the return value for log syncing consistent

Currently we will return 1 or -EAGAIN if we decide we need to commit
the transaction rather than sync the log.  In practice this doesn't
really matter, we interpret any !0 and !BTRFS_NO_LOG_SYNC as needing to
commit the transaction.  However this makes it hard to figure out what
the correct thing to do is.

Fix this up by defining BTRFS_LOG_FORCE_COMMIT and using this in all the
places where we want to force the transaction to be committed.

CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/file.c

@@ -2308,7 +2308,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 	btrfs_release_log_ctx_extents(&ctx);
 	if (ret < 0) {
 		/* Fallthrough and commit/free transaction. */
-		ret = 1;
+		ret = BTRFS_LOG_FORCE_COMMIT;
 	}
 
 	/* we've logged all the items and now have a consistent

fs/btrfs/tree-log.c

@@ -171,7 +171,7 @@ static int start_log_trans(struct btrfs_trans_handle *trans,
 		int index = (root->log_transid + 1) % 2;
 
 		if (btrfs_need_log_full_commit(trans)) {
-			ret = -EAGAIN;
+			ret = BTRFS_LOG_FORCE_COMMIT;
 			goto out;
 		}
 
@@ -194,7 +194,7 @@ static int start_log_trans(struct btrfs_trans_handle *trans,
 		 * writing.
 		 */
 		if (zoned && !created) {
-			ret = -EAGAIN;
+			ret = BTRFS_LOG_FORCE_COMMIT;
 			goto out;
 		}
 
@@ -3121,7 +3121,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 
 	/* bail out if we need to do a full commit */
 	if (btrfs_need_log_full_commit(trans)) {
-		ret = -EAGAIN;
+		ret = BTRFS_LOG_FORCE_COMMIT;
 		mutex_unlock(&root->log_mutex);
 		goto out;
 	}
@@ -3222,7 +3222,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 		}
 		btrfs_wait_tree_log_extents(log, mark);
 		mutex_unlock(&log_root_tree->log_mutex);
-		ret = -EAGAIN;
+		ret = BTRFS_LOG_FORCE_COMMIT;
 		goto out;
 	}
 
@@ -3261,7 +3261,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 		blk_finish_plug(&plug);
 		btrfs_wait_tree_log_extents(log, mark);
 		mutex_unlock(&log_root_tree->log_mutex);
-		ret = -EAGAIN;
+		ret = BTRFS_LOG_FORCE_COMMIT;
 		goto out_wake_log_root;
 	}
 
@@ -5848,7 +5848,7 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans,
 	    inode_only == LOG_INODE_ALL &&
 	    inode->last_unlink_trans >= trans->transid) {
 		btrfs_set_log_full_commit(trans);
-		ret = 1;
+		ret = BTRFS_LOG_FORCE_COMMIT;
 		goto out_unlock;
 	}
 
@@ -6562,12 +6562,12 @@ static int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
 	bool log_dentries = false;
 
 	if (btrfs_test_opt(fs_info, NOTREELOG)) {
-		ret = 1;
+		ret = BTRFS_LOG_FORCE_COMMIT;
 		goto end_no_trans;
 	}
 
 	if (btrfs_root_refs(&root->root_item) == 0) {
-		ret = 1;
+		ret = BTRFS_LOG_FORCE_COMMIT;
 		goto end_no_trans;
 	}
 
@@ -6665,7 +6665,7 @@ static int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
 end_trans:
 	if (ret < 0) {
 		btrfs_set_log_full_commit(trans);
-		ret = 1;
+		ret = BTRFS_LOG_FORCE_COMMIT;
 	}
 
 	if (ret)

fs/btrfs/tree-log.h

@@ -12,6 +12,9 @@
 /* return value for btrfs_log_dentry_safe that means we don't need to log it at all */
 #define BTRFS_NO_LOG_SYNC 256
 
+/* We can't use the tree log for whatever reason, force a transaction commit */
+#define BTRFS_LOG_FORCE_COMMIT				(1)
+
 struct btrfs_log_ctx {
 	int log_ret;
 	int log_transid;