1 files changed, 154 insertions, 0 deletions

diff --git a/net/ceph/pagelist.c b/net/ceph/pagelist.c
new file mode 100644
index 000000000000..13cb409a7bba
--- /dev/null
+++ b/net/ceph/pagelist.c
@@ -0,0 +1,154 @@
+
+#include <linux/module.h>
+#include <linux/gfp.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/ceph/pagelist.h>
+
+static void ceph_pagelist_unmap_tail(struct ceph_pagelist *pl)
+{
+        if (pl->mapped_tail) {
+                struct page *page = list_entry(pl->head.prev, struct page, lru);
+                kunmap(page);
+                pl->mapped_tail = NULL;
+        }
+}
+
+int ceph_pagelist_release(struct ceph_pagelist *pl)
+{
+        ceph_pagelist_unmap_tail(pl);
+        while (!list_empty(&pl->head)) {
+                struct page *page = list_first_entry(&pl->head, struct page,
+                                                     lru);
+                list_del(&page->lru);
+                __free_page(page);
+        }
+        ceph_pagelist_free_reserve(pl);
+        return 0;
+}
+EXPORT_SYMBOL(ceph_pagelist_release);
+
+static int ceph_pagelist_addpage(struct ceph_pagelist *pl)
+{
+        struct page *page;
+
+        if (!pl->num_pages_free) {
+                page = __page_cache_alloc(GFP_NOFS);
+        } else {
+                page = list_first_entry(&pl->free_list, struct page, lru);
+                list_del(&page->lru);
+                --pl->num_pages_free;
+        }
+        if (!page)
+                return -ENOMEM;
+        pl->room += PAGE_SIZE;
+        ceph_pagelist_unmap_tail(pl);
+        list_add_tail(&page->lru, &pl->head);
+        pl->mapped_tail = kmap(page);
+        return 0;
+}
+
+int ceph_pagelist_append(struct ceph_pagelist *pl, const void *buf, size_t len)
+{
+        while (pl->room < len) {
+                size_t bit = pl->room;
+                int ret;
+
+                memcpy(pl->mapped_tail + (pl->length & ~PAGE_CACHE_MASK),
+                       buf, bit);
+                pl->length += bit;
+                pl->room -= bit;
+                buf += bit;
+                len -= bit;
+                ret = ceph_pagelist_addpage(pl);
+                if (ret)
+                        return ret;
+        }
+
+        memcpy(pl->mapped_tail + (pl->length & ~PAGE_CACHE_MASK), buf, len);
+        pl->length += len;
+        pl->room -= len;
+        return 0;
+}
+EXPORT_SYMBOL(ceph_pagelist_append);
+
+/**
+ * Allocate enough pages for a pagelist to append the given amount
+ * of data without without allocating.
+ * Returns: 0 on success, -ENOMEM on error.
+ */
+int ceph_pagelist_reserve(struct ceph_pagelist *pl, size_t space)
+{
+        if (space <= pl->room)
+                return 0;
+        space -= pl->room;
+        space = (space + PAGE_SIZE - 1) >> PAGE_SHIFT;   /* conv to num pages */
+
+        while (space > pl->num_pages_free) {
+                struct page *page = __page_cache_alloc(GFP_NOFS);
+                if (!page)
+                        return -ENOMEM;
+                list_add_tail(&page->lru, &pl->free_list);
+                ++pl->num_pages_free;
+        }
+        return 0;
+}
+EXPORT_SYMBOL(ceph_pagelist_reserve);
+
+/**
+ * Free any pages that have been preallocated.
+ */
+int ceph_pagelist_free_reserve(struct ceph_pagelist *pl)
+{
+        while (!list_empty(&pl->free_list)) {
+                struct page *page = list_first_entry(&pl->free_list,
+                                                     struct page, lru);
+                list_del(&page->lru);
+                __free_page(page);
+                --pl->num_pages_free;
+        }
+        BUG_ON(pl->num_pages_free);
+        return 0;
+}
+EXPORT_SYMBOL(ceph_pagelist_free_reserve);
+
+/**
+ * Create a truncation point.
+ */
+void ceph_pagelist_set_cursor(struct ceph_pagelist *pl,
+                              struct ceph_pagelist_cursor *c)
+{
+        c->pl = pl;
+        c->page_lru = pl->head.prev;
+        c->room = pl->room;
+}
+EXPORT_SYMBOL(ceph_pagelist_set_cursor);
+
+/**
+ * Truncate a pagelist to the given point. Move extra pages to reserve.
+ * This won't sleep.
+ * Returns: 0 on success,
+ *          -EINVAL if the pagelist doesn't match the trunc point pagelist
+ */
+int ceph_pagelist_truncate(struct ceph_pagelist *pl,
+                           struct ceph_pagelist_cursor *c)
+{
+        struct page *page;
+
+        if (pl != c->pl)
+                return -EINVAL;
+        ceph_pagelist_unmap_tail(pl);
+        while (pl->head.prev != c->page_lru) {
+                page = list_entry(pl->head.prev, struct page, lru);
+                list_del(&page->lru);                /* remove from pagelist */
+                list_add_tail(&page->lru, &pl->free_list); /* add to reserve */
+                ++pl->num_pages_free;
+        }
+        pl->room = c->room;
+        if (!list_empty(&pl->head)) {
+                page = list_entry(pl->head.prev, struct page, lru);
+                pl->mapped_tail = kmap(page);
+        }
+        return 0;
+}
+EXPORT_SYMBOL(ceph_pagelist_truncate);