1. 09 Nov, 2013 5 commits
    • Al Viro's avatar
    • Al Viro's avatar
      get rid of s_files and files_lock · eee5cc27
      Al Viro authored
      The only thing we need it for is alt-sysrq-r (emergency remount r/o)
      and these days we can do just as well without going through the
      list of files.
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
    • Al Viro's avatar
      get rid of {lock,unlock}_rcu_walk() · 8b61e74f
      Al Viro authored
      those have become aliases for rcu_read_{lock,unlock}()
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
    • Al Viro's avatar
      RCU'd vfsmounts · 48a066e7
      Al Viro authored
      * RCU-delayed freeing of vfsmounts
      * vfsmount_lock replaced with a seqlock (mount_lock)
      * sequence number from mount_lock is stored in nameidata->m_seq and
      used when we exit RCU mode
      * new vfsmount flag - MNT_SYNC_UMOUNT.  Set by umount_tree() when its
      caller knows that vfsmount will have no surviving references.
      * synchronize_rcu() done between unlocking namespace_sem in namespace_unlock()
      and doing pending mntput().
      * new helper: legitimize_mnt(mnt, seq).  Checks the mount_lock sequence
      number against seq, then grabs reference to mnt.  Then it rechecks mount_lock
      again to close the race and either returns success or drops the reference it
      has acquired.  The subtle point is that in case of MNT_SYNC_UMOUNT we can
      simply decrement the refcount and sod off - aforementioned synchronize_rcu()
      makes sure that final mntput() won't come until we leave RCU mode.  We need
      that, since we don't want to end up with some lazy pathwalk racing with
      umount() and stealing the final mntput() from it - caller of umount() may
      expect it to return only once the fs is shut down and we don't want to break
      that.  In other cases (i.e. with MNT_SYNC_UMOUNT absent) we have to do
      full-blown mntput() in case of mount_lock sequence number mismatch happening
      just as we'd grabbed the reference, but in those cases we won't be stealing
      the final mntput() from anything that would care.
      * mntput_no_expire() doesn't lock anything on the fast path now.  Incidentally,
      SMP and UP cases are handled the same way - no ifdefs there.
      * normal pathname resolution does *not* do any writes to mount_lock.  It does,
      of course, bump the refcounts of vfsmount and dentry in the very end, but that's
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
    • Al Viro's avatar
      switch shrink_dcache_for_umount() to use of d_walk() · 42c32608
      Al Viro authored
      we have too many iterators in fs/dcache.c...
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
  2. 25 Oct, 2013 35 commits