Re: triggers for sending inode forgets

Pranith Kumar Karampuri <pkarampu@xxxxxxxxxx> · Sat, 05 Jul 2014 08:47:37 +0530



    On 07/05/2014 08:17 AM, Anand Avati
      wrote:

    
          On Fri, Jul 4, 2014 at 7:03 PM,
            Pranith Kumar Karampuri <pkarampu@xxxxxxxxxx>
            wrote:

            hi,

                  I work on glusterfs and was debugging a memory leak.
              Need your help in figuring out if something is done
              properly or not.

              When a file is looked up for the first time in gluster
              through fuse, gluster remembers the parent-inode, basename
              for that inode. Whenever an unlink/rmdir/(lookup gives
              ENOENT) happens then corresponding forgetting of
              parent-inode, basename happens.
            

            This is because of the path resolver explicitly calls
              d_invalidate() on a dentry when d_revalidate() fails on
              it.
            

              In all other cases it relies on fuse to send forget of an
              inode to release these associations. I was wondering what
              are the trigger points for sending forgets by fuse.

              
              Lets say M0, M1 are fuse mounts of same volume.

              1) Mount 'M0' creates a file 'a'

              2) Mount 'M1' of deletes file 'a'

              
              M0 never touches 'a' anymore. Will a forget be sent on
              inode of 'a'? If yes when?

            
            Really depends on when the memory manager decides to
              start reclaiming memory from dcache due to memory
              pressure. If the system is not under memory pressure, and
              if the stale dentry is never encountered by the path
              resolver, the inode may never receive a forget. To keep a
              tight utilization limit on the inode/dcache, you will have
              to proactively fuse_notify_inval_entry
                on old/deleted files.
          
        
    Thanks for this info Avati. I see that in fuse-bridge for glusterfs
    there is a setxattr interface to do that. Is that what you are
    referring to?

    
    Pranith

    
            Thanks
          
        
_______________________________________________
Gluster-devel mailing list
Gluster-devel@xxxxxxxxxxx
http://supercolony.gluster.org/mailman/listinfo/gluster-devel