Commit 51069e4a authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFSv4: Fix a deadlock between nfs4_open_recover_helper() and delegreturn 



If we're asked to recover open state while a delegation return is
outstanding, then the state manager thread cannot use a cached open, so
if the server returns a delegation, we can end up deadlocked behind the
pending delegreturn.
To avoid this problem, let's just ask the server not to give us a
delegation unless we're explicitly reclaiming one.

Fixes: be36e185 ("NFSv4: nfs4_open_recover_helper() must set share access")
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent e83458fc

fs/nfs/nfs4proc.c

+12 −7
Original line number Diff line number Diff line
@@ -2134,15 +2134,15 @@ static int nfs4_open_recover_helper(struct nfs4_opendata *opendata, 
				    fmode_t fmode)

{

	struct nfs4_state *newstate;

	struct nfs_server *server = NFS_SB(opendata->dentry->d_sb);

	int openflags = opendata->o_arg.open_flags;

	int ret;



	if (!nfs4_mode_match_open_stateid(opendata->state, fmode))

		return 0;

	opendata->o_arg.open_flags = 0;

	opendata->o_arg.fmode = fmode;

	opendata->o_arg.share_access = nfs4_map_atomic_open_share(

			NFS_SB(opendata->dentry->d_sb),

			fmode, 0);

	opendata->o_arg.share_access =

		nfs4_map_atomic_open_share(server, fmode, openflags);

	memset(&opendata->o_res, 0, sizeof(opendata->o_res));

	memset(&opendata->c_res, 0, sizeof(opendata->c_res));

	nfs4_init_opendata_res(opendata);
@@ -2724,10 +2724,15 @@ static int _nfs4_open_expired(struct nfs_open_context *ctx, struct nfs4_state *s 
	struct nfs4_opendata *opendata;

	int ret;



	opendata = nfs4_open_recoverdata_alloc(ctx, state,

			NFS4_OPEN_CLAIM_FH);

	opendata = nfs4_open_recoverdata_alloc(ctx, state, NFS4_OPEN_CLAIM_FH);

	if (IS_ERR(opendata))

		return PTR_ERR(opendata);

	/*

	 * We're not recovering a delegation, so ask for no delegation.

	 * Otherwise the recovery thread could deadlock with an outstanding

	 * delegation return.

	 */

	opendata->o_arg.open_flags = O_DIRECT;

	ret = nfs4_open_recover(opendata, state);

	if (ret == -ESTALE)

		d_drop(ctx->dentry);