• Jeff Layton's avatar
    nfsd: don't set a FL_LAYOUT lease for flexfiles layouts · 1983a66f
    Jeff Layton authored
    We currently can hit a deadlock (of sorts) when trying to use flexfiles
    layouts with XFS. XFS will call break_layout when something wants to
    write to the file. In the case of the (super-simple) flexfiles layout
    driver in knfsd, the MDS and DS are the same machine.
    
    The client can get a layout and then issue a v3 write to do its I/O. XFS
    will then call xfs_break_layouts, which will cause a CB_LAYOUTRECALL to
    be issued to the client. The client however can't return the layout
    until the v3 WRITE completes, but XFS won't allow the write to proceed
    until the layout is returned.
    
    Christoph says:
    
        XFS only cares about block-like layouts where the client has direct
        access to the file blocks.  I'd need to look how to propagate the
        flag into break_layout, but in principle we don't need to do any
        recalls on truncate ever for file and flexfile layouts.
    
    If we're never going to recall the layout, then we don't even need to
    set the lease at all. Just skip doing so on flexfiles layouts by
    adding a new flag to struct nfsd4_layout_ops and skipping the lease
    setting and removal when that flag is true.
    
    Cc: Christoph Hellwig <hch@lst.de>
    Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
    Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
    1983a66f
flexfilelayout.c 3.38 KB