Difference between invalidating and deleting dentry

[Nikolaus Rath <Nikolaus@rath.org>]

Hello,

I just added an example to FUSE that illustrates use of the
fuse_lowlevel_notify_inval_entry() function. However, when writing it I
realized that I don't actually fully understand how this function
differs from fuse_lowlevel_notify_delete(). Could someone shed some
light on this?

Currently, the FUSE documentation says:

fuse_lowlevel_notify_inval_entry:
   Notify to invalidate parent attributes and the dentry matching
   parent/name

fuse_lowlevel_notify_delete:
   Notify to invalidate parent attributes and delete the dentry matching
   parent/name if the dentry's inode number matches child (otherwise it
   will invalidate the matching dentry).


But what exactly is the difference between deleting and invalidating a
dentry? In each case, isn't the resulting behavior the same, in that the
next time someone tries to access this (parent_inode,entry_name)
combination a lookup() request will be send to the FUSE process?


Thanks,
-Nikolaus

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