ceph: handle LOOKUP_RCU in ceph_d_revalidate

We can now handle the snapshot cases under RCU, as well as the
non-snapshot case when we don't need to queue up a lease renewal
allow LOOKUP_RCU walks to proceed under those conditions.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Yan, Zheng <zyan@redhat.com>

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 60dcca1..c64a0b7 100644 (file)
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1214,15 +1214,19 @@ static int ceph_d_revalidate(struct dentry *dentry, unsigned int flags)
        struct dentry *parent;
        struct inode *dir;
 
-       if (flags & LOOKUP_RCU)
-               return -ECHILD;
+       if (flags & LOOKUP_RCU) {
+               parent = ACCESS_ONCE(dentry->d_parent);
+               dir = d_inode_rcu(parent);
+               if (!dir)
+                       return -ECHILD;
+       } else {
+               parent = dget_parent(dentry);
+               dir = d_inode(parent);
+       }
 
        dout("d_revalidate %p '%pd' inode %p offset %lld\n", dentry,
             dentry, d_inode(dentry), ceph_dentry(dentry)->offset);
 
-       parent = dget_parent(dentry);
-       dir = d_inode(parent);
-
        /* always trust cached snapped dentries, snapdir dentry */
        if (ceph_snap(dir) != CEPH_NOSNAP) {
                dout("d_revalidate %p '%pd' inode %p is SNAPPED\n", dentry,
@@ -1249,6 +1253,9 @@ static int ceph_d_revalidate(struct dentry *dentry, unsigned int flags)
                struct ceph_mds_request *req;
                int op, mask, err;
 
+               if (flags & LOOKUP_RCU)
+                       return -ECHILD;
+
                op = ceph_snap(dir) == CEPH_SNAPDIR ?
                        CEPH_MDS_OP_LOOKUPSNAP : CEPH_MDS_OP_LOOKUP;
                req = ceph_mdsc_create_request(mdsc, op, USE_ANY_MDS);
@@ -1284,7 +1291,8 @@ static int ceph_d_revalidate(struct dentry *dentry, unsigned int flags)
                ceph_dir_clear_complete(dir);
        }
 
-       dput(parent);
+       if (!(flags & LOOKUP_RCU))
+               dput(parent);
        return valid;
 }