Commit 74fc55ab authored by NeilBrown's avatar NeilBrown Committed by Anna Schumaker
Browse files

nfs_localio: duplicate nfs_close_local_fh() 



nfs_close_local_fh() is called from two different places for quite
different use case.

It is called from nfs_uuid_put() when the nfs_uuid is being detached -
possibly because the nfs server is not longer serving that filesystem.
In this case there will always be an nfs_uuid and so rcu_read_lock() is
not needed.

It is also called when the nfs_file_localio is no longer needed.  In
this case there may not be an active nfs_uuid.

These two can race, and handling the race properly while avoiding
excessive locking will require different handling on each side.

This patch prepares the way by opencoding nfs_close_local_fh() into
nfs_uuid_put(), then simplifying the code there as befits the context.

Fixes: 86e00412 ("nfs: cache all open LOCALIO nfsd_file(s) in client")
Signed-off-by: default avatarNeilBrown <neil@brown.name>
Signed-off-by: default avatarAnna Schumaker <anna.schumaker@oracle.com>
parent e6f7e148

fs/nfs_common/nfslocalio.c

+20 −1
Original line number Diff line number Diff line
@@ -171,7 +171,26 @@ static bool nfs_uuid_put(nfs_uuid_t *nfs_uuid) 


	/* Walk list of files and ensure their last references dropped */

	list_for_each_entry_safe(nfl, tmp, &local_files, list) {

		nfs_close_local_fh(nfl);

		struct nfsd_file *ro_nf;

		struct nfsd_file *rw_nf;



		ro_nf = unrcu_pointer(xchg(&nfl->ro_file, NULL));

		rw_nf = unrcu_pointer(xchg(&nfl->rw_file, NULL));



		spin_lock(&nfs_uuid->lock);

		/* Remove nfl from nfs_uuid->files list */

		list_del_init(&nfl->list);

		spin_unlock(&nfs_uuid->lock);

		/* Now we can allow racing nfs_close_local_fh() to

		 * skip the locking.

		 */

		RCU_INIT_POINTER(nfl->nfs_uuid, NULL);



		if (ro_nf)

			nfs_to_nfsd_file_put_local(ro_nf);

		if (rw_nf)

			nfs_to_nfsd_file_put_local(rw_nf);



		cond_resched();

	}