bisync: fix listings missing concurrent modifications - fixes #8359

Before this change, there was a bug affecting listing files when:

- a given bisync run had changes in the 2to1 direction
AND
- the run had NO changes in the 1to2 direction
AND
- at least one of the changed files changed AGAIN during the run
(specifically, after the initial march and before the transfers.)

In this situation, the listings on one side would still retain the prior version
of the changed file, potentially causing conflicts or errors.

This change fixes the issue by making sure that if we're updating the listings
on one side, we must also update the other. (We previously tried to skip it for
efficiency, but this failed to account for the possibility that a changed file
could change again during the run.)

cmd/bisync/deltas.go

@@ -286,7 +286,7 @@ func (b *bisyncRun) findDeltas(fctx context.Context, f fs.Fs, oldListing string,
 }
 
 // applyDeltas
-func (b *bisyncRun) applyDeltas(ctx context.Context, ds1, ds2 *deltaSet) (changes1, changes2 bool, results2to1, results1to2 []Results, queues queues, err error) {
+func (b *bisyncRun) applyDeltas(ctx context.Context, ds1, ds2 *deltaSet) (results2to1, results1to2 []Results, queues queues, err error) {
 	path1 := bilib.FsPath(b.fs1)
 	path2 := bilib.FsPath(b.fs2)
 
@@ -367,7 +367,7 @@ func (b *bisyncRun) applyDeltas(ctx context.Context, ds1, ds2 *deltaSet) (change
 		}
 	}
 
-	//if there are potential conflicts to check, check them all here (outside the loop) in one fell swoop
+	// if there are potential conflicts to check, check them all here (outside the loop) in one fell swoop
 	matches, err := b.checkconflicts(ctxCheck, filterCheck, b.fs1, b.fs2)
 
 	for _, file := range ds1.sort() {
@@ -392,7 +392,7 @@ func (b *bisyncRun) applyDeltas(ctx context.Context, ds1, ds2 *deltaSet) (change
 			} else if d2.is(deltaOther) {
 				b.indent("!WARNING", file, "New or changed in both paths")
 
-				//if files are identical, leave them alone instead of renaming
+				// if files are identical, leave them alone instead of renaming
 				if (dirs1.has(file) || dirs1.has(alias)) && (dirs2.has(file) || dirs2.has(alias)) {
 					fs.Infof(nil, "This is a directory, not a file. Skipping equality check and will not rename: %s", file)
 					ls1.getPut(file, skippedDirs1)
@@ -486,7 +486,6 @@ func (b *bisyncRun) applyDeltas(ctx context.Context, ds1, ds2 *deltaSet) (change
 
 	// Do the batch operation
 	if copy2to1.NotEmpty() && !b.InGracefulShutdown {
-		changes1 = true
 		b.indent("Path2", "Path1", "Do queued copies to")
 		ctx = b.setBackupDir(ctx, 1)
 		results2to1, err = b.fastCopy(ctx, b.fs2, b.fs1, copy2to1, "copy2to1")
@@ -498,12 +497,11 @@ func (b *bisyncRun) applyDeltas(ctx context.Context, ds1, ds2 *deltaSet) (change
 			return
 		}
 
-		//copy empty dirs from path2 to path1 (if --create-empty-src-dirs)
+		// copy empty dirs from path2 to path1 (if --create-empty-src-dirs)
 		b.syncEmptyDirs(ctx, b.fs1, copy2to1, dirs2, &results2to1, "make")
 	}
 
 	if copy1to2.NotEmpty() && !b.InGracefulShutdown {
-		changes2 = true
 		b.indent("Path1", "Path2", "Do queued copies to")
 		ctx = b.setBackupDir(ctx, 2)
 		results1to2, err = b.fastCopy(ctx, b.fs1, b.fs2, copy1to2, "copy1to2")
@@ -515,7 +513,7 @@ func (b *bisyncRun) applyDeltas(ctx context.Context, ds1, ds2 *deltaSet) (change
 			return
 		}
 
-		//copy empty dirs from path1 to path2 (if --create-empty-src-dirs)
+		// copy empty dirs from path1 to path2 (if --create-empty-src-dirs)
 		b.syncEmptyDirs(ctx, b.fs2, copy1to2, dirs1, &results1to2, "make")
 	}
 
@@ -523,7 +521,7 @@ func (b *bisyncRun) applyDeltas(ctx context.Context, ds1, ds2 *deltaSet) (change
 		if err = b.saveQueue(delete1, "delete1"); err != nil {
 			return
 		}
-		//propagate deletions of empty dirs from path2 to path1 (if --create-empty-src-dirs)
+		// propagate deletions of empty dirs from path2 to path1 (if --create-empty-src-dirs)
 		b.syncEmptyDirs(ctx, b.fs1, delete1, dirs1, &results2to1, "remove")
 	}
 
@@ -531,7 +529,7 @@ func (b *bisyncRun) applyDeltas(ctx context.Context, ds1, ds2 *deltaSet) (change
 		if err = b.saveQueue(delete2, "delete2"); err != nil {
 			return
 		}
-		//propagate deletions of empty dirs from path1 to path2 (if --create-empty-src-dirs)
+		// propagate deletions of empty dirs from path1 to path2 (if --create-empty-src-dirs)
 		b.syncEmptyDirs(ctx, b.fs2, delete2, dirs2, &results1to2, "remove")
 	}