pNFS: Parse the results of layoutget on open even if permissions checks fail

Even if the results of the permissions checks failed, we should parse
the results of the layout on open call so that we can return the
layout if required.
Note that we also want to ignore the sequence counter for whether or not
a layout recall occurred. If the recall pertained to our OPEN, then the
callback will know, and will attempt to wait for us to finih processing
anyway.
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/callback_proc.c

@@ -331,8 +331,6 @@ static u32 initiate_bulk_draining(struct nfs_client *clp,
 static u32 do_callback_layoutrecall(struct nfs_client *clp,
 				    struct cb_layoutrecallargs *args)
 {
-	write_seqcount_begin(&clp->cl_callback_count);
-	write_seqcount_end(&clp->cl_callback_count);
 	if (args->cbl_recall_type == RETURN_FILE)
 		return initiate_file_draining(clp, args);
 	return initiate_bulk_draining(clp, args);

fs/nfs/nfs4proc.c

@@ -2843,6 +2843,9 @@ static int _nfs4_open_and_get_state(struct nfs4_opendata *opendata,
 				nfs_save_change_attribute(d_inode(opendata->dir)));
 	}
 
+	/* Parse layoutget results before we check for access */
+	pnfs_parse_lgopen(state->inode, opendata->lgp, ctx);
+
 	ret = nfs4_opendata_access(sp->so_cred, opendata, state, fmode, flags);
 	if (ret != 0)
 		goto out;
@@ -2851,8 +2854,6 @@ static int _nfs4_open_and_get_state(struct nfs4_opendata *opendata,
 		nfs_inode_attach_open_context(ctx);
 		if (read_seqcount_retry(&sp->so_reclaim_seqcount, seq))
 			nfs4_schedule_stateid_recovery(server, state);
-		else
-			pnfs_parse_lgopen(state->inode, opendata->lgp, ctx);
 	}
 
 out:

fs/nfs/pnfs.c

@@ -1018,7 +1018,6 @@ pnfs_alloc_init_layoutget_args(struct inode *ino,
 	nfs4_stateid_copy(&lgp->args.stateid, stateid);
 	lgp->gfp_flags = gfp_flags;
 	lgp->cred = get_rpccred(ctx->cred);
-	lgp->callback_count = raw_seqcount_begin(&server->nfs_client->cl_callback_count);
 	return lgp;
 }
 
@@ -2181,9 +2180,6 @@ void pnfs_parse_lgopen(struct inode *ino, struct nfs4_layoutget *lgp,
 	} else
 		lo = NFS_I(lgp->args.inode)->layout;
 
-	if (read_seqcount_retry(&srv->nfs_client->cl_callback_count,
-				lgp->callback_count))
-		return;
 	lseg = pnfs_layout_process(lgp);
 	if (!IS_ERR(lseg)) {
 		iomode = lgp->args.range.iomode;

include/linux/nfs_fs_sb.h

@@ -28,7 +28,6 @@ struct nfs41_impl_id;
 struct nfs_client {
 	refcount_t		cl_count;
 	atomic_t		cl_mds_count;
-	seqcount_t		cl_callback_count;
 	int			cl_cons_state;	/* current construction state (-ve: init error) */
 #define NFS_CS_READY		0		/* ready to be used */
 #define NFS_CS_INITING		1		/* busy initialising */

include/linux/nfs_xdr.h

@@ -271,7 +271,6 @@ struct nfs4_layoutget {
 	struct nfs4_layoutget_args args;
 	struct nfs4_layoutget_res res;
 	struct rpc_cred *cred;
-	unsigned callback_count;
 	gfp_t gfp_flags;
 };