From: Valerie Aurora <vaurora@xxxxxxxxxx>
needs_lookup_union() tests if a path could possibly require a union
lookup.
---
fs/union.h | 17 +++++++++++++++++
include/linux/dcache.h | 2 ++
2 files changed, 19 insertions(+), 0 deletions(-)
diff --git a/fs/union.h b/fs/union.h
index 89527b7..54427ba 100644
--- a/fs/union.h
+++ b/fs/union.h
@@ -64,6 +64,22 @@ struct path *union_find_dir(struct dentry *dentry, unsigned int layer)
return &dentry->d_union_stack->u_dirs[layer];
}
+static inline
+int needs_lookup_union(struct path *parent_path, struct path *path)
+{
+ if (!IS_DIR_UNIONED(parent_path->dentry))
+ return 0;
+
+ /* Either already built or crossed a mountpoint to not-unioned mnt */
+ /* XXX are bind mounts root? think not */
+ if (IS_ROOT(path->dentry))
+ return 0;
+
+ /* It's okay not to have the lock; will recheck in lookup_union() */
+ /* XXX set for root dentry at mount? */
+ return !(path->dentry->d_flags & DCACHE_UNION_LOOKUP_DONE);
+}
+
#else /* CONFIG_UNION_MOUNT */
#define IS_MNT_UNION(x) (0)
@@ -73,6 +89,7 @@ struct path *union_find_dir(struct dentry *dentry, unsigned int layer)
#define union_add_dir(x, y, z) ({ BUG(); (0); })
#define union_find_dir(x, y) ({ BUG(); (NULL); })
#define union_create_topmost_dir(w, x, y, z) ({ BUG(); (0); })
+#define needs_lookup_union(x, y) ({ (0); })
#endif /* CONFIG_UNION_MOUNT */
#endif /* __KERNEL__ */
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index eb8fbf8..f5442ec 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -244,6 +244,8 @@ struct dentry_operations {
#define DCACHE_MANAGED_DENTRY \
(DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
+#define DCACHE_UNION_LOOKUP_DONE 0x080000 /* Union lookup was called on this dentry */
+
extern seqlock_t rename_lock;
static inline int dname_external(struct dentry *dentry)
--
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