ceph: support ceph_pagelist for message payload
The ceph_pagelist is a simple list of whole pages, strung together via
their lru list_head. It facilitates encoding to a "buffer" of unknown
size. Allow its use in place of the ceph_msg page vector.
This will be used to fix the huge buffer preallocation woes of MDS
reconnection.
Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/pagelist.h b/fs/ceph/pagelist.h
new file mode 100644
index 0000000..e8a4187
--- /dev/null
+++ b/fs/ceph/pagelist.h
@@ -0,0 +1,54 @@
+#ifndef __FS_CEPH_PAGELIST_H
+#define __FS_CEPH_PAGELIST_H
+
+#include <linux/list.h>
+
+struct ceph_pagelist {
+ struct list_head head;
+ void *mapped_tail;
+ size_t length;
+ size_t room;
+};
+
+static inline void ceph_pagelist_init(struct ceph_pagelist *pl)
+{
+ INIT_LIST_HEAD(&pl->head);
+ pl->mapped_tail = NULL;
+ pl->length = 0;
+ pl->room = 0;
+}
+extern int ceph_pagelist_release(struct ceph_pagelist *pl);
+
+extern int ceph_pagelist_append(struct ceph_pagelist *pl, void *d, size_t l);
+
+static inline int ceph_pagelist_encode_64(struct ceph_pagelist *pl, u64 v)
+{
+ __le64 ev = cpu_to_le64(v);
+ return ceph_pagelist_append(pl, &ev, sizeof(ev));
+}
+static inline int ceph_pagelist_encode_32(struct ceph_pagelist *pl, u32 v)
+{
+ __le32 ev = cpu_to_le32(v);
+ return ceph_pagelist_append(pl, &ev, sizeof(ev));
+}
+static inline int ceph_pagelist_encode_16(struct ceph_pagelist *pl, u16 v)
+{
+ __le16 ev = cpu_to_le16(v);
+ return ceph_pagelist_append(pl, &ev, sizeof(ev));
+}
+static inline int ceph_pagelist_encode_8(struct ceph_pagelist *pl, u8 v)
+{
+ return ceph_pagelist_append(pl, &v, 1);
+}
+static inline int ceph_pagelist_encode_string(struct ceph_pagelist *pl,
+ char *s, size_t len)
+{
+ int ret = ceph_pagelist_encode_32(pl, len);
+ if (ret)
+ return ret;
+ if (len)
+ return ceph_pagelist_append(pl, s, len);
+ return 0;
+}
+
+#endif