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authorAndrew Price <anprice@redhat.com>2021-03-15 12:24:00 +0000
committerAndreas Gruenbacher <agruenba@redhat.com>2021-03-15 15:32:42 +0100
commit62dd0f98a0e5668424270b47a0c2e973795faba7 (patch)
tree7d0c03dd9bc1890eed1fef4987226f6aca6ff0d8 /fs/gfs2/super.c
parentb77b5fdd052e7ee61b35164abb10e8433d3160e8 (diff)
downloadlinux-62dd0f98a0e5668424270b47a0c2e973795faba7.tar.gz
gfs2: Flag a withdraw if init_threads() fails
Interrupting mount with ^C quickly enough can cause the kthread_run()
calls in gfs2's init_threads() to fail and the error path leads to a
deadlock on the s_umount rwsem. The abridged chain of events is:

  [mount path]
  get_tree_bdev()
    sget_fc()
      alloc_super()
        down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING); [acquired]
    gfs2_fill_super()
      gfs2_make_fs_rw()
        init_threads()
          kthread_run()
            ( Interrupted )
      [Error path]
      gfs2_gl_hash_clear()
        flush_workqueue(glock_workqueue)
          wait_for_completion()

  [workqueue context]
  glock_work_func()
    run_queue()
      do_xmote()
        freeze_go_sync()
          freeze_super()
            down_write(&sb->s_umount) [deadlock]

In freeze_go_sync() there is a gfs2_withdrawn() check that we can use to
make sure freeze_super() is not called in the error path, so add a
gfs2_withdraw_delayed() call when init_threads() fails.

Ref: https://bugzilla.kernel.org/show_bug.cgi?id=212231

Reported-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Diffstat (limited to 'fs/gfs2/super.c')
-rw-r--r--fs/gfs2/super.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 97076d3f562f..9e91c9d92bd6 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -162,8 +162,10 @@ int gfs2_make_fs_rw(struct gfs2_sbd *sdp)
 	int error;
 
 	error = init_threads(sdp);
-	if (error)
+	if (error) {
+		gfs2_withdraw_delayed(sdp);
 		return error;
+	}
 
 	j_gl->gl_ops->go_inval(j_gl, DIO_METADATA);
 	if (gfs2_withdrawn(sdp)) {