• Jeff Layton's avatar
    cifs: convert oplock breaks to use slow_work facility (try #4) · 3bc303c2
    Jeff Layton authored
    This is the fourth respin of the patch to convert oplock breaks to
    use the slow_work facility.
    
    A customer of ours was testing a backport of one of the earlier
    patchsets, and hit a "Busy inodes after umount..." problem. An oplock
    break job had raced with a umount, and the superblock got torn down and
    its memory reused. When the oplock break job tried to dereference the
    inode->i_sb, the kernel oopsed.
    
    This patchset has the oplock break job hold an inode and vfsmount
    reference until the oplock break completes.  With this, there should be
    no need to take a tcon reference (the vfsmount implicitly holds one
    already).
    
    Currently, when an oplock break comes in there's a chance that the
    oplock break job won't occur if the allocation of the oplock_q_entry
    fails. There are also some rather nasty races in the allocation and
    handling these structs.
    
    Rather than allocating oplock queue entries when an oplock break comes
    in, add a few extra fields to the cifsFileInfo struct. Get rid of the
    dedicated cifs_oplock_thread as well and queue the oplock break job to
    the slow_work thread pool.
    
    This approach also has the advantage that the oplock break jobs can
    potentially run in parallel rather than be serialized like they are
    today.
    Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
    Signed-off-by: default avatarSteve French <sfrench@us.ibm.com>
    3bc303c2
file.c 65.8 KB