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Subject: [PATCH] nfs: Fix fscache volume key rendering for endianness
From:   David Howells <dhowells@redhat.com>
To:     trond.myklebust@hammerspace.com, anna@kernel.org
Cc:     Dave Wysochanski <dwysocha@redhat.com>,
        Jeff Layton <jlayton@kernel.org>, linux-nfs@vger.kernel.org,
        linux-cachefs@redhat.com, torvalds@linux-foundation.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Thu, 19 May 2022 08:51:32 +0100
Message-ID: <165294669215.3283481.13374322806917745974.stgit@warthog.procyon.org.uk>
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Fix fscache volume key rendering for endianness.  Convert the BE numbers in
the address to host-endian before printing them so that they're consistent
if the cache is copied between architectures.

Question: This change could lead to misidentification of a volume directory
in the cache on a LE machine (it's unlikely because the port number as well
as the address numbers all get flipped), but it was introduced in -rc1 in
this cycle so probably isn't in any distro kernels yet.  Should I add a
version number to enforce non-matching?

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Dave Wysochanski <dwysocha@redhat.com>
cc: Trond Myklebust <trond.myklebust@hammerspace.com>
cc: Anna Schumaker <anna@kernel.org>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-nfs@vger.kernel.org
cc: linux-cachefs@redhat.com
---

 fs/nfs/fscache.c |   14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index f73c09a9cf0a..0e5572b192b2 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -54,17 +54,17 @@ static bool nfs_fscache_get_client_key(struct nfs_client *clp,
 
 	switch (clp->cl_addr.ss_family) {
 	case AF_INET:
-		if (!nfs_append_int(key, _len, sin->sin_port) ||
-		    !nfs_append_int(key, _len, sin->sin_addr.s_addr))
+		if (!nfs_append_int(key, _len, ntohs(sin->sin_port)) ||
+		    !nfs_append_int(key, _len, ntohl(sin->sin_addr.s_addr)))
 			return false;
 		return true;
 
 	case AF_INET6:
-		if (!nfs_append_int(key, _len, sin6->sin6_port) ||
-		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[0]) ||
-		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[1]) ||
-		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[2]) ||
-		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[3]))
+		if (!nfs_append_int(key, _len, ntohs(sin6->sin6_port)) ||
+		    !nfs_append_int(key, _len, ntohl(sin6->sin6_addr.s6_addr32[0])) ||
+		    !nfs_append_int(key, _len, ntohl(sin6->sin6_addr.s6_addr32[1])) ||
+		    !nfs_append_int(key, _len, ntohl(sin6->sin6_addr.s6_addr32[2])) ||
+		    !nfs_append_int(key, _len, ntohl(sin6->sin6_addr.s6_addr32[3])))
 			return false;
 		return true;