• Ian Kent's avatar
    autofs4: Add d_manage() dentry operation · b5b80177
    Ian Kent authored
    This patch required a previous patch to add the ->d_automount()
    dentry operation.
    
    Add a function to use the newly defined ->d_manage() dentry operation
    for blocking during mount and expire.
    
    Whether the VFS calls the dentry operations d_automount() and d_manage()
    is controled by the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags. autofs
    uses the d_automount() operation to callback to user space to request
    mount operations and the d_manage() operation to block walks into mounts
    that are under construction or destruction.
    
    In order to prevent these functions from being called unnecessarily the
    DMANAGED_* flags are cleared for cases which would cause this. In the
    common case the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags are both
    set for dentrys waiting to be mounted. The DMANAGED_TRANSIT flag is
    cleared upon successful mount request completion and set during expire
    runs, both during the dentry expire check, and if selected for expire,
    is left set until a subsequent successful mount request completes.
    
    The exception to this is the so-called rootless multi-mount which has
    no actual mount at its base. In this case the DMANAGED_AUTOMOUNT flag
    is cleared upon successful mount request completion as well and set
    again after a successful expire.
    Signed-off-by: default avatarIan Kent <raven@themaw.net>
    Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
    Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
    b5b80177
autofs_i.h 9.73 KB