fix: `-x` is applied to traversal as well.

Previously `dua` would cross filesystems for traversal and simply not
yield them, which somewhat defeated the purpose.

Now it will avoid traversing into filesystem entries that are on a different
filesystem, which should improve its performance visibly whenever multiple
filesystems are involved.

3 files changed, 18 insertions, 10 deletions

diff --git a/src/aggregate.rs b/src/aggregate.rs
index a724a57..6e1cc2f 100644
--- a/src/aggregate.rs
+++ b/src/aggregate.rs
@@ -97,7 +97,7 @@ pub fn aggregate(
                 continue;
             }
         };
-        for entry in walk_options.iter_from_path(path.as_ref()) {
+        for entry in walk_options.iter_from_path(path.as_ref(), device_id) {
             stats.entries_traversed += 1;
             progress.throttled(|out| {
                 write!(out, "Enumerating {} entries\r", stats.entries_traversed).ok();
diff --git a/src/common.rs b/src/common.rs
index f5f862e..5eb094e 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -1,3 +1,4 @@
+use crate::crossdev;
 use crate::traverse::{EntryData, Tree, TreeIndex};
 use byte_unit::{n_gb_bytes, n_gib_bytes, n_mb_bytes, n_mib_bytes, ByteUnit};
 use std::path::PathBuf;
@@ -130,8 +131,8 @@ pub struct WalkOptions {
 type WalkDir = jwalk::WalkDirGeneric<((), Option<Result<std::fs::Metadata, jwalk::Error>>)>;
 
 impl WalkOptions {
-    pub(crate) fn iter_from_path(&self, path: &Path) -> WalkDir {
-        WalkDir::new(path)
+    pub(crate) fn iter_from_path(&self, root: &Path, root_device_id: u64) -> WalkDir {
+        WalkDir::new(root)
             .follow_links(false)
             .sort(match self.sorting {
                 TraversalSorting::None => false,
@@ -140,16 +141,23 @@ impl WalkOptions {
             .skip_hidden(false)
             .process_read_dir({
                 let ignore_dirs = self.ignore_dirs.clone();
+                let cross_filesystems = self.cross_filesystems;
                 move |_, _, _, dir_entry_results| {
                     dir_entry_results.iter_mut().for_each(|dir_entry_result| {
                         if let Ok(dir_entry) = dir_entry_result {
+                            let metadata = dir_entry.metadata();
+
                             if dir_entry.file_type.is_file() || dir_entry.file_type().is_symlink() {
-                                dir_entry.client_state = Some(dir_entry.metadata());
-                            }
-                            if dir_entry.file_type.is_dir()
-                                && ignore_dirs.contains(&dir_entry.path())
-                            {
-                                dir_entry.read_children_path = None;
+                                dir_entry.client_state = Some(metadata);
+                            } else if dir_entry.file_type.is_dir() {
+                                let ok_for_fs = cross_filesystems
+                                    || metadata
+                                        .as_ref()
+                                        .map(|m| crossdev::is_same_device(root_device_id, m))
+                                        .unwrap_or(true);
+                                if !ok_for_fs || ignore_dirs.contains(&dir_entry.path()) {
+                                    dir_entry.read_children_path = None;
+                                }
                             }
                         }
                     })
diff --git a/src/traverse.rs b/src/traverse.rs
index 1bbece4..f61ab41 100644
--- a/src/traverse.rs
+++ b/src/traverse.rs
@@ -103,7 +103,7 @@ impl Traversal {
                 }
             };
             for (eid, entry) in walk_options
-                .iter_from_path(path.as_ref())
+                .iter_from_path(path.as_ref(), device_id)
                 .into_iter()
                 .enumerate()
             {