linux-kernel - [PATCH 15/18] NFS: discard NFS_RPC_SWAPFLAGS and RPC_TASK

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Message-ID: <163969850333.20885.17464715871688147966.stgit@noble.brown>
Date:   Fri, 17 Dec 2021 10:48:23 +1100
From:   NeilBrown <neilb@...e.de>
To:     Trond Myklebust <trond.myklebust@...merspace.com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        Chuck Lever <chuck.lever@...cle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...e.de>,
        Christoph Hellwig <hch@...radead.org>,
        David Howells <dhowells@...hat.com>
Cc:     linux-nfs@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 15/18] NFS: discard NFS_RPC_SWAPFLAGS and RPC_TASK_ROOTCREDS

NFS_RPC_SWAPFLAGS is only used for READ requests.
It sets RPC_TASK_SWAPPER which gives some memory-allocation priority to
requests.  This is not needed for swap READ - though it is for writes
where it is set via a different mechanism.

RPC_TASK_ROOTCREDS causes the 'machine' credential to be used.
This is not needed as the root credential is saved when the swap file is
opened, and this is used for all IO.

So NFS_RPC_SWAPFLAGS isn't needed, and as it is the only user of
RPC_TASK_ROOTCREDS, that isn't needed either.

Remove both.

Signed-off-by: NeilBrown <neilb@...e.de>
---
 fs/nfs/read.c                 |    4 ----
 include/linux/nfs_fs.h        |    5 -----
 include/linux/sunrpc/sched.h  |    1 -
 include/trace/events/sunrpc.h |    1 -
 net/sunrpc/auth.c             |    2 +-
 5 files changed, 1 insertion(+), 12 deletions(-)

diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index d11af2a9299c..a8f2b884306c 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -194,10 +194,6 @@ static void nfs_initiate_read(struct nfs_pgio_header *hdr,
 			      const struct nfs_rpc_ops *rpc_ops,
 			      struct rpc_task_setup *task_setup_data, int how)
 {
-	struct inode *inode = hdr->inode;
-	int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0;
-
-	task_setup_data->flags |= swap_flags;
 	rpc_ops->read_setup(hdr, msg);
 	trace_nfs_initiate_read(hdr);
 }
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 3a210478f665..5dce9129fe64 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -45,11 +45,6 @@
  */
 #define NFS_MAX_TRANSPORTS 16
 
-/*
- * These are the default flags for swap requests
- */
-#define NFS_RPC_SWAPFLAGS		(RPC_TASK_SWAPPER|RPC_TASK_ROOTCREDS)
-
 /*
  * Size of the NFS directory verifier
  */
diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h
index db964bb63912..56710f8056d3 100644
--- a/include/linux/sunrpc/sched.h
+++ b/include/linux/sunrpc/sched.h
@@ -124,7 +124,6 @@ struct rpc_task_setup {
 #define RPC_TASK_MOVEABLE	0x0004		/* nfs4.1+ rpc tasks */
 #define RPC_TASK_NULLCREDS	0x0010		/* Use AUTH_NULL credential */
 #define RPC_CALL_MAJORSEEN	0x0020		/* major timeout seen */
-#define RPC_TASK_ROOTCREDS	0x0040		/* force root creds */
 #define RPC_TASK_DYNAMIC	0x0080		/* task was kmalloc'ed */
 #define	RPC_TASK_NO_ROUND_ROBIN	0x0100		/* send requests on "main" xprt */
 #define RPC_TASK_SOFT		0x0200		/* Use soft timeouts */
diff --git a/include/trace/events/sunrpc.h b/include/trace/events/sunrpc.h
index 3a99358c262b..141dc34a450e 100644
--- a/include/trace/events/sunrpc.h
+++ b/include/trace/events/sunrpc.h
@@ -311,7 +311,6 @@ TRACE_EVENT(rpc_request,
 		{ RPC_TASK_MOVEABLE, "MOVEABLE" },			\
 		{ RPC_TASK_NULLCREDS, "NULLCREDS" },			\
 		{ RPC_CALL_MAJORSEEN, "MAJORSEEN" },			\
-		{ RPC_TASK_ROOTCREDS, "ROOTCREDS" },			\
 		{ RPC_TASK_DYNAMIC, "DYNAMIC" },			\
 		{ RPC_TASK_NO_ROUND_ROBIN, "NO_ROUND_ROBIN" },		\
 		{ RPC_TASK_SOFT, "SOFT" },				\
diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index 6bfa19f9fa6a..682fcd24bf43 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -670,7 +670,7 @@ rpcauth_bindcred(struct rpc_task *task, const struct cred *cred, int flags)
 	/* If machine cred couldn't be bound, try a root cred */
 	if (new)
 		;
-	else if (cred == &machine_cred || (flags & RPC_TASK_ROOTCREDS))
+	else if (cred == &machine_cred)
 		new = rpcauth_bind_root_cred(task, lookupflags);
 	else if (flags & RPC_TASK_NULLCREDS)
 		new = authnull_ops.lookup_cred(NULL, NULL, 0);