gfs2: Allow gfs2_xattr_set to be called with the glock held

On the following call path:

  gfs2_setattr -> setattr_prepare -> ... ->
    cap_inode_killpriv -> ... ->
      gfs2_xattr_set

the glock is locked in gfs2_setattr, so check for recursive locking in
gfs2_xattr_set as gfs2_xattr_get already does.  While at it, get rid of
need_unlock in gfs2_xattr_get.

Fixes xfstest generic/093.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Acked-by: Abhijith Das <adas@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>

1 files changed, 16 insertions, 7 deletions

diff --git a/fs/gfs2/xattr.c b/fs/gfs2/xattr.c
index 3e96dce21c1c..05de20954659 100644
--- a/fs/gfs2/xattr.c
+++ b/fs/gfs2/xattr.c
@@ -610,7 +610,6 @@ static int gfs2_xattr_get(const struct xattr_handler *handler,
 {
         struct gfs2_inode *ip = GFS2_I(inode);
         struct gfs2_holder gh;
-        bool need_unlock = false;
         int ret;
 
         /* During lookup, SELinux calls this function with the glock locked. */
@@ -619,10 +618,11 @@ static int gfs2_xattr_get(const struct xattr_handler *handler,
                 ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &gh);
                 if (ret)
                         return ret;
-                need_unlock = true;
+        } else {
+                gfs2_holder_mark_uninitialized(&gh);
         }
         ret = __gfs2_xattr_get(inode, name, buffer, size, handler->flags);
-        if (need_unlock)
+        if (gfs2_holder_initialized(&gh))
                 gfs2_glock_dq_uninit(&gh);
         return ret;
 }
@@ -1244,11 +1244,20 @@ static int gfs2_xattr_set(const struct xattr_handler *handler,
         if (ret)
                 return ret;
 
-        ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
-        if (ret)
-                return ret;
+        /* May be called from gfs_setattr with the glock locked. */
+
+        if (!gfs2_glock_is_locked_by_me(ip->i_gl)) {
+                ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
+                if (ret)
+                        return ret;
+        } else {
+                if (WARN_ON_ONCE(ip->i_gl->gl_state != LM_ST_EXCLUSIVE))
+                        return -EIO;
+                gfs2_holder_mark_uninitialized(&gh);
+        }
         ret = __gfs2_xattr_set(inode, name, value, size, flags, handler->flags);
-        gfs2_glock_dq_uninit(&gh);
+        if (gfs2_holder_initialized(&gh))
+                gfs2_glock_dq_uninit(&gh);
         return ret;
 }