On Tue, Apr 30, 2019 at 3:27 AM Jeff Layton <jlayton@xxxxxxxxxx> wrote:
>
> While it may be slightly more efficient, it's probably not worthwhile to
> optimize for the case that clone_dentry_name handles. We can get the
> same result by just calling ceph_mdsc_build_path when the parent isn't
> locked, with less code duplication.
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> fs/ceph/mds_client.c | 41 +++--------------------------------------
> 1 file changed, 3 insertions(+), 38 deletions(-)
>
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index 74cb3078ea63..e8245df09691 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -2170,55 +2170,20 @@ char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *pbase,
> return path;
> }
>
> -/* Duplicate the dentry->d_name.name safely */
> -static int clone_dentry_name(struct dentry *dentry, const char **ppath,
> - int *ppathlen)
> -{
> - u32 len;
> - char *name;
> -retry:
> - len = READ_ONCE(dentry->d_name.len);
> - name = kmalloc(len + 1, GFP_NOFS);
> - if (!name)
> - return -ENOMEM;
> -
> - spin_lock(&dentry->d_lock);
> - if (dentry->d_name.len != len) {
> - spin_unlock(&dentry->d_lock);
> - kfree(name);
> - goto retry;
> - }
> - memcpy(name, dentry->d_name.name, len);
> - spin_unlock(&dentry->d_lock);
> -
> - name[len] = '\0';
> - *ppath = name;
> - *ppathlen = len;
> - return 0;
> -}
> -
> static int build_dentry_path(struct dentry *dentry, struct inode *dir,
> const char **ppath, int *ppathlen, u64 *pino,
> bool *pfreepath, bool parent_locked)
> {
> - int ret;
> char *path;
>
> rcu_read_lock();
> if (!dir)
> dir = d_inode_rcu(dentry->d_parent);
> - if (dir && ceph_snap(dir) == CEPH_NOSNAP) {
> + if (dir && parent_locked && ceph_snap(dir) == CEPH_NOSNAP) {
> *pino = ceph_ino(dir);
> rcu_read_unlock();
> - if (parent_locked) {
> - *ppath = dentry->d_name.name;
> - *ppathlen = dentry->d_name.len;
> - } else {
> - ret = clone_dentry_name(dentry, ppath, ppathlen);
> - if (ret)
> - return ret;
> - *pfreepath = true;
> - }
> + *ppath = dentry->d_name.name;
> + *ppathlen = dentry->d_name.len;
> return 0;
> }
> rcu_read_unlock();
Reviewed-by: "Yan, Zheng" <zyan@xxxxxxxxxx>
> --
> 2.20.1
>
