From: Valerie Aurora <vaurora@xxxxxxxxxx>
needs_lookup_union() tests if a path could possibly require a union
lookup.
Signed-off-by: Valerie Aurora <valerie.aurora@xxxxxxxxx>
---
fs/union.h | 16 ++++++++++++++++
include/linux/dcache.h | 1 +
2 files changed, 17 insertions(+), 0 deletions(-)
diff --git a/fs/union.h b/fs/union.h
index c496823..9efb177 100644
--- a/fs/union.h
+++ b/fs/union.h
@@ -57,6 +57,21 @@ extern int union_add_dir(struct path *, struct path *, unsigned int);
extern int union_create_topmost_dir(struct path *, struct qstr *, struct path *,
struct path *);
+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);
+}
+
static inline struct path *union_find_dir(struct dentry *dentry,
unsigned int layer) {
BUG_ON(layer >= dentry->d_sb->s_union_count);
@@ -72,6 +87,7 @@ static inline struct path *union_find_dir(struct dentry *dentry,
#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 ddf3d2d..c37b621 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -209,6 +209,7 @@ d_iput: no no no yes
#define DCACHE_WHITEOUT 0x0200 /* Stop lookup in a unioned file system */
#define DCACHE_FALLTHRU 0x0400 /* Continue lookup below an opaque dir */
+#define DCACHE_UNION_LOOKUP_DONE 0x0800 /* Union lookup was called on this dentry */
extern spinlock_t dcache_lock;
extern seqlock_t rename_lock;
--
1.7.0.4
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