nfs: fscache: use timespec64 in inode auxdata

nfs currently behaves differently on 32-bit and 64-bit kernels regarding
the on-disk format of nfs_fscache_inode_auxdata.

That format should really be the same on any kernel, and we should avoid
the 'timespec' type in order to remove that from the kernel later on.

Using plain 'timespec64' would not be good here, since that includes
implied padding and would possibly leak kernel stack data to the on-disk
format on 32-bit architectures.

struct __kernel_timespec would work as a replacement, but open-coding
the two struct members in nfs_fscache_inode_auxdata makes it more
obvious what's going on here, and keeps the current format for 64-bit
architectures.

Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

fs/nfs/fscache-index.c

@@ -84,8 +84,10 @@ enum fscache_checkaux nfs_fscache_inode_check_aux(void *cookie_netfs_data,
 		return FSCACHE_CHECKAUX_OBSOLETE;
 
 	memset(&auxdata, 0, sizeof(auxdata));
-	auxdata.mtime = timespec64_to_timespec(nfsi->vfs_inode.i_mtime);
-	auxdata.ctime = timespec64_to_timespec(nfsi->vfs_inode.i_ctime);
+	auxdata.mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
+	auxdata.mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
+	auxdata.ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
+	auxdata.ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
 
 	if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
 		auxdata.change_attr = inode_peek_iversion_raw(&nfsi->vfs_inode);

fs/nfs/fscache.c

@@ -238,8 +238,10 @@ void nfs_fscache_init_inode(struct inode *inode)
 		return;
 
 	memset(&auxdata, 0, sizeof(auxdata));
-	auxdata.mtime = timespec64_to_timespec(nfsi->vfs_inode.i_mtime);
-	auxdata.ctime = timespec64_to_timespec(nfsi->vfs_inode.i_ctime);
+	auxdata.mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
+	auxdata.mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
+	auxdata.ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
+	auxdata.ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
 
 	if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
 		auxdata.change_attr = inode_peek_iversion_raw(&nfsi->vfs_inode);
@@ -263,8 +265,10 @@ void nfs_fscache_clear_inode(struct inode *inode)
 	dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n", nfsi, cookie);
 
 	memset(&auxdata, 0, sizeof(auxdata));
-	auxdata.mtime = timespec64_to_timespec(nfsi->vfs_inode.i_mtime);
-	auxdata.ctime = timespec64_to_timespec(nfsi->vfs_inode.i_ctime);
+	auxdata.mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
+	auxdata.mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
+	auxdata.ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
+	auxdata.ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
 	fscache_relinquish_cookie(cookie, &auxdata, false);
 	nfsi->fscache = NULL;
 }
@@ -305,8 +309,10 @@ void nfs_fscache_open_file(struct inode *inode, struct file *filp)
 		return;
 
 	memset(&auxdata, 0, sizeof(auxdata));
-	auxdata.mtime = timespec64_to_timespec(nfsi->vfs_inode.i_mtime);
-	auxdata.ctime = timespec64_to_timespec(nfsi->vfs_inode.i_ctime);
+	auxdata.mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
+	auxdata.mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
+	auxdata.ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
+	auxdata.ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
 
 	if (inode_is_open_for_write(inode)) {
 		dfprintk(FSCACHE, "NFS: nfsi 0x%p disabling cache\n", nfsi);

fs/nfs/fscache.h

@@ -62,9 +62,11 @@ struct nfs_fscache_key {
  * cache object.
  */
 struct nfs_fscache_inode_auxdata {
-	struct timespec	mtime;
-	struct timespec	ctime;
-	u64		change_attr;
+	s64	mtime_sec;
+	s64	mtime_nsec;
+	s64	ctime_sec;
+	s64	ctime_nsec;
+	u64	change_attr;
 };
 
 /*