nfs/localio: restore creds before releasing pageio data

Otherwise if the nfsd filecache code releases the nfsd_file
immediately, it can trigger the BUG_ON(cred == current->cred) in
__put_cred() when it puts the nfsd_file->nf_file->f-cred.

Fixes: b9f5dd57f4a5 ("nfs/localio: use dedicated workqueues for filesystem read and write")
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Mike Snitzer <snitzer@kernel.org>
Link: https://lore.kernel.org/r/20250807164938.2395136-1-smayhew@redhat.com
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

diff --git a/fs/nfs/localio.c b/fs/nfs/localio.c
index bd5fca28589989f63ce3ea2e8436dd7243978709..bdb82a19136aaa209756acd6e0d8e81c886405bc 100644 (file)
--- a/fs/nfs/localio.c
+++ b/fs/nfs/localio.c
@@ -453,12 +453,13 @@ static void nfs_local_call_read(struct work_struct *work)
        nfs_local_iter_init(&iter, iocb, READ);
 
        status = filp->f_op->read_iter(&iocb->kiocb, &iter);
+
+       revert_creds(save_cred);
+
        if (status != -EIOCBQUEUED) {
                nfs_local_read_done(iocb, status);
                nfs_local_pgio_release(iocb);
        }
-
-       revert_creds(save_cred);
 }
 
 static int
@@ -648,14 +649,15 @@ static void nfs_local_call_write(struct work_struct *work)
        file_start_write(filp);
        status = filp->f_op->write_iter(&iocb->kiocb, &iter);
        file_end_write(filp);
+
+       revert_creds(save_cred);
+       current->flags = old_flags;
+
        if (status != -EIOCBQUEUED) {
                nfs_local_write_done(iocb, status);
                nfs_local_vfs_getattr(iocb);
                nfs_local_pgio_release(iocb);
        }
-
-       revert_creds(save_cred);
-       current->flags = old_flags;
 }
 
 static int