The d_lock was used in prepend_path() to protect dentry->d_name from
being changed under the hood. As the caller of prepend_path() has
to take the rename_lock before calling into it, there is no chance
that d_name will be changed. The d_lock lock is only needed when the
rename_lock is not taken.

Signed-off-by: Waiman Long <waiman.l...@hp.com>
---
 fs/dcache.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index b1487e2..0e911fc 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2547,6 +2547,7 @@ static int prepend_name(char **buffer, int *buflen, 
struct qstr *name)
  * @buflen: pointer to buffer length
  *
  * Caller holds the rename_lock.
+ * There is no need to lock the dentry as its name cannot be changed.
  */
 static int prepend_path(const struct path *path,
                        const struct path *root,
@@ -2573,9 +2574,7 @@ static int prepend_path(const struct path *path,
                }
                parent = dentry->d_parent;
                prefetch(parent);
-               spin_lock(&dentry->d_lock);
                error = prepend_name(buffer, buflen, &dentry->d_name);
-               spin_unlock(&dentry->d_lock);
                if (!error)
                        error = prepend(buffer, buflen, "/", 1);
                if (error)
-- 
1.7.1

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