9p: v9fs_fid_add() can't fail now
[linux-3.10.git] / fs / 9p / fid.c
index 3585636..73ca550 100644 (file)
  *
  */
 
-int v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
+void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
 {
-       struct v9fs_dentry *dent;
-
-       P9_DPRINTK(P9_DEBUG_VFS, "fid %d dentry %s\n",
-                                       fid->fid, dentry->d_name.name);
-
-       dent = dentry->d_fsdata;
-       if (!dent) {
-               dent = kmalloc(sizeof(struct v9fs_dentry), GFP_KERNEL);
-               if (!dent)
-                       return -ENOMEM;
-
-               spin_lock_init(&dent->lock);
-               INIT_LIST_HEAD(&dent->fidlist);
-               dentry->d_fsdata = dent;
-       }
-
-       spin_lock(&dent->lock);
-       list_add(&fid->dlist, &dent->fidlist);
-       spin_unlock(&dent->lock);
-
-       return 0;
+       spin_lock(&dentry->d_lock);
+       hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata);
+       spin_unlock(&dentry->d_lock);
 }
 
 /**
@@ -74,24 +56,26 @@ int v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
  *
  */
 
-static struct p9_fid *v9fs_fid_find(struct dentry *dentry, u32 uid, int any)
+static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
 {
-       struct v9fs_dentry *dent;
        struct p9_fid *fid, *ret;
 
-       P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n",
-               dentry->d_name.name, dentry, uid, any);
-       dent = (struct v9fs_dentry *) dentry->d_fsdata;
+       p9_debug(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n",
+                dentry->d_name.name, dentry, from_kuid(&init_user_ns, uid),
+                any);
        ret = NULL;
-       if (dent) {
-               spin_lock(&dent->lock);
-               list_for_each_entry(fid, &dent->fidlist, dlist) {
-                       if (any || fid->uid == uid) {
+       /* we'll recheck under lock if there's anything to look in */
+       if (dentry->d_fsdata) {
+               struct hlist_head *h = (struct hlist_head *)&dentry->d_fsdata;
+               struct hlist_node *n;
+               spin_lock(&dentry->d_lock);
+               hlist_for_each_entry(fid, n, h, dlist) {
+                       if (any || uid_eq(fid->uid, uid)) {
                                ret = fid;
                                break;
                        }
                }
-               spin_unlock(&dent->lock);
+               spin_unlock(&dentry->d_lock);
        }
 
        return ret;
@@ -125,45 +109,17 @@ err_out:
        return -ENOMEM;
 }
 
-/**
- * v9fs_fid_lookup - lookup for a fid, try to walk if not found
- * @dentry: dentry to look for fid in
- *
- * Look for a fid in the specified dentry for the current user.
- * If no fid is found, try to create one walking from a fid from the parent
- * dentry (if it has one), or the root dentry. If the user haven't accessed
- * the fs yet, attach now and walk from the root.
- */
-
-struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
+static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
+                                              kuid_t uid, int any)
 {
-       int i, n, l, clone, any, access;
-       u32 uid;
-       struct p9_fid *fid, *old_fid = NULL;
        struct dentry *ds;
-       struct v9fs_session_info *v9ses;
        char **wnames, *uname;
+       int i, n, l, clone, access;
+       struct v9fs_session_info *v9ses;
+       struct p9_fid *fid, *old_fid = NULL;
 
-       v9ses = v9fs_inode2v9ses(dentry->d_inode);
+       v9ses = v9fs_dentry2v9ses(dentry);
        access = v9ses->flags & V9FS_ACCESS_MASK;
-       switch (access) {
-       case V9FS_ACCESS_SINGLE:
-       case V9FS_ACCESS_USER:
-               uid = current_fsuid();
-               any = 0;
-               break;
-
-       case V9FS_ACCESS_ANY:
-               uid = v9ses->uid;
-               any = 1;
-               break;
-
-       default:
-               uid = ~0;
-               any = 0;
-               break;
-       }
-
        fid = v9fs_fid_find(dentry, uid, any);
        if (fid)
                return fid;
@@ -242,12 +198,52 @@ struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
        }
        kfree(wnames);
 fid_out:
-       v9fs_fid_add(dentry, fid);
+       if (!IS_ERR(fid))
+               v9fs_fid_add(dentry, fid);
 err_out:
        up_read(&v9ses->rename_sem);
        return fid;
 }
 
+/**
+ * v9fs_fid_lookup - lookup for a fid, try to walk if not found
+ * @dentry: dentry to look for fid in
+ *
+ * Look for a fid in the specified dentry for the current user.
+ * If no fid is found, try to create one walking from a fid from the parent
+ * dentry (if it has one), or the root dentry. If the user haven't accessed
+ * the fs yet, attach now and walk from the root.
+ */
+
+struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
+{
+       kuid_t uid;
+       int  any, access;
+       struct v9fs_session_info *v9ses;
+
+       v9ses = v9fs_dentry2v9ses(dentry);
+       access = v9ses->flags & V9FS_ACCESS_MASK;
+       switch (access) {
+       case V9FS_ACCESS_SINGLE:
+       case V9FS_ACCESS_USER:
+       case V9FS_ACCESS_CLIENT:
+               uid = current_fsuid();
+               any = 0;
+               break;
+
+       case V9FS_ACCESS_ANY:
+               uid = v9ses->uid;
+               any = 1;
+               break;
+
+       default:
+               uid = INVALID_UID;
+               any = 0;
+               break;
+       }
+       return v9fs_fid_lookup_with_uid(dentry, uid, any);
+}
+
 struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
 {
        struct p9_fid *fid, *ret;
@@ -259,3 +255,39 @@ struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
        ret = p9_client_walk(fid, 0, NULL, 1);
        return ret;
 }
+
+static struct p9_fid *v9fs_fid_clone_with_uid(struct dentry *dentry, kuid_t uid)
+{
+       struct p9_fid *fid, *ret;
+
+       fid = v9fs_fid_lookup_with_uid(dentry, uid, 0);
+       if (IS_ERR(fid))
+               return fid;
+
+       ret = p9_client_walk(fid, 0, NULL, 1);
+       return ret;
+}
+
+struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
+{
+       int err;
+       struct p9_fid *fid;
+
+       fid = v9fs_fid_clone_with_uid(dentry, GLOBAL_ROOT_UID);
+       if (IS_ERR(fid))
+               goto error_out;
+       /*
+        * writeback fid will only be used to write back the
+        * dirty pages. We always request for the open fid in read-write
+        * mode so that a partial page write which result in page
+        * read can work.
+        */
+       err = p9_client_open(fid, O_RDWR);
+       if (err < 0) {
+               p9_client_clunk(fid);
+               fid = ERR_PTR(err);
+               goto error_out;
+       }
+error_out:
+       return fid;
+}