cifs: define inode-level cache object and register them

Define inode-level data storage objects (managed by cifsInodeInfo structs).
Each inode-level object is created in a super-block level object and is itself
a data storage object in to which pages from the inode are stored.

The inode object is keyed by UniqueId. The coherency data being used is
LastWriteTime, LastChangeTime and end of file reported by the server.

Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/cache.c

@@ -215,3 +215,86 @@ const struct fscache_cookie_def cifs_fscache_super_index_def = {
 	.check_aux = cifs_fscache_super_check_aux,
 };
 
+/*
+ * Auxiliary data attached to CIFS inode within the cache
+ */
+struct cifs_fscache_inode_auxdata {
+	struct timespec	last_write_time;
+	struct timespec	last_change_time;
+	u64		eof;
+};
+
+static uint16_t cifs_fscache_inode_get_key(const void *cookie_netfs_data,
+					   void *buffer, uint16_t maxbuf)
+{
+	const struct cifsInodeInfo *cifsi = cookie_netfs_data;
+	uint16_t keylen;
+
+	/* use the UniqueId as the key */
+	keylen = sizeof(cifsi->uniqueid);
+	if (keylen > maxbuf)
+		keylen = 0;
+	else
+		memcpy(buffer, &cifsi->uniqueid, keylen);
+
+	return keylen;
+}
+
+static void
+cifs_fscache_inode_get_attr(const void *cookie_netfs_data, uint64_t *size)
+{
+	const struct cifsInodeInfo *cifsi = cookie_netfs_data;
+
+	*size = cifsi->vfs_inode.i_size;
+}
+
+static uint16_t
+cifs_fscache_inode_get_aux(const void *cookie_netfs_data, void *buffer,
+			   uint16_t maxbuf)
+{
+	struct cifs_fscache_inode_auxdata auxdata;
+	const struct cifsInodeInfo *cifsi = cookie_netfs_data;
+
+	memset(&auxdata, 0, sizeof(auxdata));
+	auxdata.eof = cifsi->server_eof;
+	auxdata.last_write_time = cifsi->vfs_inode.i_mtime;
+	auxdata.last_change_time = cifsi->vfs_inode.i_ctime;
+
+	if (maxbuf > sizeof(auxdata))
+		maxbuf = sizeof(auxdata);
+
+	memcpy(buffer, &auxdata, maxbuf);
+
+	return maxbuf;
+}
+
+static enum
+fscache_checkaux cifs_fscache_inode_check_aux(void *cookie_netfs_data,
+					      const void *data,
+					      uint16_t datalen)
+{
+	struct cifs_fscache_inode_auxdata auxdata;
+	struct cifsInodeInfo *cifsi = cookie_netfs_data;
+
+	if (datalen != sizeof(auxdata))
+		return FSCACHE_CHECKAUX_OBSOLETE;
+
+	memset(&auxdata, 0, sizeof(auxdata));
+	auxdata.eof = cifsi->server_eof;
+	auxdata.last_write_time = cifsi->vfs_inode.i_mtime;
+	auxdata.last_change_time = cifsi->vfs_inode.i_ctime;
+
+	if (memcmp(data, &auxdata, datalen) != 0)
+		return FSCACHE_CHECKAUX_OBSOLETE;
+
+	return FSCACHE_CHECKAUX_OKAY;
+}
+
+const struct fscache_cookie_def cifs_fscache_inode_object_def = {
+	.name		= "CIFS.uniqueid",
+	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,
+	.get_key	= cifs_fscache_inode_get_key,
+	.get_attr	= cifs_fscache_inode_get_attr,
+	.get_aux	= cifs_fscache_inode_get_aux,
+	.check_aux	= cifs_fscache_inode_check_aux,
+};