kclient: setattr on inode (not path) if holding WR cap

For newly created files, this avoids contention in the MDS over the dentry
xlock (e.g., for an untar).

It is slightly risky, because we could race with a caps release and MDS
cache trim.  Pretty unlikely, however, because cap release would also
involve MDS journaling.

diff --git a/src/kernel/inode.c b/src/kernel/inode.c
index 6a7d36e2bed8fc6fa2d907548bda4ac76c636af5..faf01bfa3a10220be05b4d6a32ec5ce26090c4a1 100644 (file)
--- a/src/kernel/inode.c
+++ b/src/kernel/inode.c
@@ -1415,8 +1415,10 @@ static struct ceph_mds_request *prepare_setattr(struct ceph_mds_client *mdsc,
        int pathlen;
        struct ceph_mds_request *req;
        u64 pathbase;
+       int issued = ceph_caps_issued(ceph_inode(dentry->d_inode));
 
-       if (ia_valid & ATTR_FILE) {
+       if ((ia_valid & ATTR_FILE) ||
+           (issued & (CEPH_CAP_WR|CEPH_CAP_WRBUFFER))) {
                dout(5, "prepare_setattr dentry %p (inode %llx.%llx)\n", dentry,
                     ceph_vinop(dentry->d_inode));
                req = ceph_mdsc_create_request(mdsc, op,