[PATCH 1/3] NFS: flexfilelayout: return ERR_PTR from nfs4_ff_alloc_deviceid_node() and fix caller

["Peng Fan (OSS)" <peng.fan@oss.nxp.com>]

From: Peng Fan <peng.fan@nxp.com>

nfs4_ff_alloc_deviceid_node() initialized 'ret' but never returned it,
triggering W=1:

  fs/nfs/flexfilelayout/flexfilelayoutdev.c:56:9: error: variable 'ret'
  set but not used [-Werror=unused-but-set-variable]

The function also returned NULL on error, dropping the specific errno
stored in 'ret'. Convert it to return ERR_PTR(ret) instead, and update
ff_layout_alloc_deviceid_node() to detect errors using IS_ERR().
This preserves the error code for callers and aligns the helper with
common ERR_PTR-returning allocation patterns. It also resolves the build
warning.

No functional change for success paths; improves error reporting.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
 fs/nfs/flexfilelayout/flexfilelayout.c    | 2 +-
 fs/nfs/flexfilelayout/flexfilelayoutdev.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c
index f67773d52830d2ab4d12dd04caccc2077d4105e0..cd175204807600ff4e33ff769e03ef7ac700a6dc 100644
--- a/fs/nfs/flexfilelayout/flexfilelayout.c
+++ b/fs/nfs/flexfilelayout/flexfilelayout.c
@@ -2566,7 +2566,7 @@ ff_layout_alloc_deviceid_node(struct nfs_server *server,
 	struct nfs4_ff_layout_ds *dsaddr;
 
 	dsaddr = nfs4_ff_alloc_deviceid_node(server, pdev, gfp_flags);
-	if (!dsaddr)
+	if (IS_ERR(dsaddr))
 		return NULL;
 	return &dsaddr->id_node;
 }
diff --git a/fs/nfs/flexfilelayout/flexfilelayoutdev.c b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
index c40395ae081429f315ccee6b73eafc742b4f01a4..9e36350b10fa84d5e2a2e6f25fce36ed504285ce 100644
--- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c
+++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
@@ -181,7 +181,7 @@ nfs4_ff_alloc_deviceid_node(struct nfs_server *server, struct pnfs_device *pdev,
 	kfree(new_ds);
 
 	dprintk("%s ERROR: returning %d\n", __func__, ret);
-	return NULL;
+	return ERR_PTR(ret);
 }
 
 static void extend_ds_error(struct nfs4_ff_layout_ds_err *err,

-- 
2.37.1