[Gluster-devel] triggers for sending inode forgets

[Pranith Kumar Karampuri]

On 07/05/2014 08:17 AM, Anand Avati wrote:
>
>
>
> On Fri, Jul 4, 2014 at 7:03 PM, Pranith Kumar Karampuri 
> <pkarampu at redhat.com <mailto:pkarampu at redhat.com>> 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

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