teach handle_mounts() to handle RCU mode

... and make the callers of __follow_mount_rcu() use handle_mounts().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namei.c b/fs/namei.c
index c34c270..37b2f82 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1393,6 +1393,18 @@ static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry,
 
        path->mnt = nd->path.mnt;
        path->dentry = dentry;
+       if (nd->flags & LOOKUP_RCU) {
+               unsigned int seq = *seqp;
+               if (unlikely(!*inode))
+                       return -ENOENT;
+               if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
+                       return 1;
+               if (unlazy_child(nd, dentry, seq))
+                       return -ECHILD;
+               // *path might've been clobbered by __follow_mount_rcu()
+               path->mnt = nd->path.mnt;
+               path->dentry = dentry;
+       }
        ret = follow_managed(path, nd);
        if (likely(ret >= 0)) {
                *inode = d_backing_inode(path->dentry);
@@ -1620,7 +1632,6 @@ static int lookup_fast(struct nameidata *nd,
                       struct path *path, struct inode **inode,
                       unsigned *seqp)
 {
-       struct vfsmount *mnt = nd->path.mnt;
        struct dentry *dentry, *parent = nd->path.dentry;
        int status = 1;
 
@@ -1658,21 +1669,8 @@ static int lookup_fast(struct nameidata *nd,
 
                *seqp = seq;
                status = d_revalidate(dentry, nd->flags);
-               if (likely(status > 0)) {
-                       /*
-                        * Note: do negative dentry check after revalidation in
-                        * case that drops it.
-                        */
-                       if (unlikely(!*inode))
-                               return -ENOENT;
-                       path->mnt = mnt;
-                       path->dentry = dentry;
-                       if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
-                               return 1;
-                       if (unlazy_child(nd, dentry, seq))
-                               return -ECHILD;
+               if (likely(status > 0))
                        return handle_mounts(nd, dentry, path, inode, seqp);
-               }
                if (unlazy_child(nd, dentry, seq))
                        return -ECHILD;
                if (unlikely(status == -ECHILD))
@@ -2361,21 +2359,11 @@ static int handle_lookup_down(struct nameidata *nd)
        unsigned seq = nd->seq;
        int err;
 
-       if (nd->flags & LOOKUP_RCU) {
-               /*
-                * don't bother with unlazy_walk on failure - we are
-                * at the very beginning of walk, so we lose nothing
-                * if we simply redo everything in non-RCU mode
-                */
-               path = nd->path;
-               if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq)))
-                       return -ECHILD;
-       } else {
+       if (!(nd->flags & LOOKUP_RCU))
                dget(nd->path.dentry);
-               err = handle_mounts(nd, nd->path.dentry, &path, &inode, &seq);
-               if (unlikely(err < 0))
-                       return err;
-       }
+       err = handle_mounts(nd, nd->path.dentry, &path, &inode, &seq);
+       if (unlikely(err < 0))
+               return err;
        path_to_nameidata(&path, nd);
        nd->inode = inode;
        nd->seq = seq;