start_removing_dentry() is similar to start_removing() but instead of
providing a name for lookup, the target dentry is given.
start_removing_dentry() checks that the dentry is still hashed and in
the parent, and if so it locks and increases the refcount so that
end_removing() can be used to finish the operation.
This is used in cachefiles, overlayfs, smb/server, and apparmor.
There will be other users including ecryptfs.
As start_removing_dentry() takes an extra reference to the dentry (to be
put by end_removing()), there is no need to explicitly take an extra
reference to stop d_delete() from using dentry_unlink_inode() to negate
the dentry - as in cachefiles_delete_object(), and ksmbd_vfs_unlink().
cachefiles_bury_object() now gets an extra ref to the victim, which is
drops. As it includes the needed end_removing() calls, the caller
doesn't need them.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20251113002050.676694-9-neilb@ownmail.net
Signed-off-by: Christian Brauner <brauner@kernel.org>
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