ceph: add pagelist_reserve, pagelist_truncate, pagelist_set_cursor

These facilitate preallocation of pages so that we can encode into the pagelist
in an atomic context.

Signed-off-by: Greg Farnum <gregf@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 21 insertions, 0 deletions

diff --git a/include/linux/ceph/pagelist.h b/include/linux/ceph/pagelist.h
index cc9327aa1c9..9660d6b0a35 100644
--- a/include/linux/ceph/pagelist.h
+++ b/include/linux/ceph/pagelist.h
@@ -8,6 +8,14 @@ struct ceph_pagelist {
         void *mapped_tail;
         size_t length;
         size_t room;
+        struct list_head free_list;
+        size_t num_pages_free;
+};
+
+struct ceph_pagelist_cursor {
+        struct ceph_pagelist *pl;   /* pagelist, for error checking */
+        struct list_head *page_lru; /* page in list */
+        size_t room;                /* room remaining to reset to */
 };
 
 static inline void ceph_pagelist_init(struct ceph_pagelist *pl)
@@ -16,11 +24,24 @@ static inline void ceph_pagelist_init(struct ceph_pagelist *pl)
         pl->mapped_tail = NULL;
         pl->length = 0;
         pl->room = 0;
+        INIT_LIST_HEAD(&pl->free_list);
+        pl->num_pages_free = 0;
 }
+
 extern int ceph_pagelist_release(struct ceph_pagelist *pl);
 
 extern int ceph_pagelist_append(struct ceph_pagelist *pl, const void *d, size_t l);
 
+extern int ceph_pagelist_reserve(struct ceph_pagelist *pl, size_t space);
+
+extern int ceph_pagelist_free_reserve(struct ceph_pagelist *pl);
+
+extern void ceph_pagelist_set_cursor(struct ceph_pagelist *pl,
+                                     struct ceph_pagelist_cursor *c);
+
+extern int ceph_pagelist_truncate(struct ceph_pagelist *pl,
+                                  struct ceph_pagelist_cursor *c);
+
 static inline int ceph_pagelist_encode_64(struct ceph_pagelist *pl, u64 v)
 {
         __le64 ev = cpu_to_le64(v);