namei: move cross-device check to __traverse_mounts

This is preparation to RESOLVE_NO_XDEV fix in following commits.
Also this commit makes LOOKUP_NO_XDEV logic more clear: now we
immediately fail with EXDEV on first mount crossing
instead of waiting for very end.

No functional change intended

Signed-off-by: Askar Safin <safinaskar@zohomail.com>
Link: https://lore.kernel.org/20250825181233.2464822-4-safinaskar@zohomail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/namei.c b/fs/namei.c
index 6e34c3317421980b1262c7742fb4d0003550942d..f0ca6f8d0a5f55aae5b2c9d7fa880ce692144341 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1489,6 +1489,10 @@ static int __traverse_mounts(struct path *path, unsigned flags, bool *jumped,
                                // here we know it's positive
                                flags = path->dentry->d_flags;
                                need_mntput = true;
+                               if (unlikely(lookup_flags & LOOKUP_NO_XDEV)) {
+                                       ret = -EXDEV;
+                                       break;
+                               }
                                continue;
                        }
                }
@@ -1518,7 +1522,6 @@ static inline int traverse_mounts(struct path *path, bool *jumped,
                                  int *count, unsigned lookup_flags)
 {
        unsigned flags = smp_load_acquire(&path->dentry->d_flags);
-       int ret;
 
        /* fastpath */
        if (likely(!(flags & DCACHE_MANAGED_DENTRY))) {
@@ -1527,11 +1530,7 @@ static inline int traverse_mounts(struct path *path, bool *jumped,
                        return -ENOENT;
                return 0;
        }
-
-       ret = __traverse_mounts(path, flags, jumped, count, lookup_flags);
-       if (*jumped && unlikely(lookup_flags & LOOKUP_NO_XDEV))
-               return -EXDEV;
-       return ret;
+       return __traverse_mounts(path, flags, jumped, count, lookup_flags);
 }
 
 int follow_down_one(struct path *path)