root/net/ceph/pagelist.c

DEFINITIONS

1. ceph_pagelist_alloc
2. ceph_pagelist_unmap_tail
3. ceph_pagelist_release
4. ceph_pagelist_addpage
5. ceph_pagelist_append
6. ceph_pagelist_reserve
7. ceph_pagelist_free_reserve
8. ceph_pagelist_set_cursor
9. ceph_pagelist_truncate

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/module.h>
   3 #include <linux/gfp.h>
   4 #include <linux/slab.h>
   5 #include <linux/pagemap.h>
   6 #include <linux/highmem.h>
   7 #include <linux/ceph/pagelist.h>
   8 
   9 struct ceph_pagelist *ceph_pagelist_alloc(gfp_t gfp_flags)
  10 {
  11         struct ceph_pagelist *pl;
  12 
  13         pl = kmalloc(sizeof(*pl), gfp_flags);
  14         if (!pl)
  15                 return NULL;
  16 
  17         INIT_LIST_HEAD(&pl->head);
  18         pl->mapped_tail = NULL;
  19         pl->length = 0;
  20         pl->room = 0;
  21         INIT_LIST_HEAD(&pl->free_list);
  22         pl->num_pages_free = 0;
  23         refcount_set(&pl->refcnt, 1);
  24 
  25         return pl;
  26 }
  27 EXPORT_SYMBOL(ceph_pagelist_alloc);
  28 
  29 static void ceph_pagelist_unmap_tail(struct ceph_pagelist *pl)
  30 {
  31         if (pl->mapped_tail) {
  32                 struct page *page = list_entry(pl->head.prev, struct page, lru);
  33                 kunmap(page);
  34                 pl->mapped_tail = NULL;
  35         }
  36 }
  37 
  38 void ceph_pagelist_release(struct ceph_pagelist *pl)
  39 {
  40         if (!refcount_dec_and_test(&pl->refcnt))
  41                 return;
  42         ceph_pagelist_unmap_tail(pl);
  43         while (!list_empty(&pl->head)) {
  44                 struct page *page = list_first_entry(&pl->head, struct page,
  45                                                      lru);
  46                 list_del(&page->lru);
  47                 __free_page(page);
  48         }
  49         ceph_pagelist_free_reserve(pl);
  50         kfree(pl);
  51 }
  52 EXPORT_SYMBOL(ceph_pagelist_release);
  53 
  54 static int ceph_pagelist_addpage(struct ceph_pagelist *pl)
  55 {
  56         struct page *page;
  57 
  58         if (!pl->num_pages_free) {
  59                 page = __page_cache_alloc(GFP_NOFS);
  60         } else {
  61                 page = list_first_entry(&pl->free_list, struct page, lru);
  62                 list_del(&page->lru);
  63                 --pl->num_pages_free;
  64         }
  65         if (!page)
  66                 return -ENOMEM;
  67         pl->room += PAGE_SIZE;
  68         ceph_pagelist_unmap_tail(pl);
  69         list_add_tail(&page->lru, &pl->head);
  70         pl->mapped_tail = kmap(page);
  71         return 0;
  72 }
  73 
  74 int ceph_pagelist_append(struct ceph_pagelist *pl, const void *buf, size_t len)
  75 {
  76         while (pl->room < len) {
  77                 size_t bit = pl->room;
  78                 int ret;
  79 
  80                 memcpy(pl->mapped_tail + (pl->length & ~PAGE_MASK),
  81                        buf, bit);
  82                 pl->length += bit;
  83                 pl->room -= bit;
  84                 buf += bit;
  85                 len -= bit;
  86                 ret = ceph_pagelist_addpage(pl);
  87                 if (ret)
  88                         return ret;
  89         }
  90 
  91         memcpy(pl->mapped_tail + (pl->length & ~PAGE_MASK), buf, len);
  92         pl->length += len;
  93         pl->room -= len;
  94         return 0;
  95 }
  96 EXPORT_SYMBOL(ceph_pagelist_append);
  97 
  98 /* Allocate enough pages for a pagelist to append the given amount
  99  * of data without without allocating.
 100  * Returns: 0 on success, -ENOMEM on error.
 101  */
 102 int ceph_pagelist_reserve(struct ceph_pagelist *pl, size_t space)
 103 {
 104         if (space <= pl->room)
 105                 return 0;
 106         space -= pl->room;
 107         space = (space + PAGE_SIZE - 1) >> PAGE_SHIFT;   /* conv to num pages */
 108 
 109         while (space > pl->num_pages_free) {
 110                 struct page *page = __page_cache_alloc(GFP_NOFS);
 111                 if (!page)
 112                         return -ENOMEM;
 113                 list_add_tail(&page->lru, &pl->free_list);
 114                 ++pl->num_pages_free;
 115         }
 116         return 0;
 117 }
 118 EXPORT_SYMBOL(ceph_pagelist_reserve);
 119 
 120 /* Free any pages that have been preallocated. */
 121 int ceph_pagelist_free_reserve(struct ceph_pagelist *pl)
 122 {
 123         while (!list_empty(&pl->free_list)) {
 124                 struct page *page = list_first_entry(&pl->free_list,
 125                                                      struct page, lru);
 126                 list_del(&page->lru);
 127                 __free_page(page);
 128                 --pl->num_pages_free;
 129         }
 130         BUG_ON(pl->num_pages_free);
 131         return 0;
 132 }
 133 EXPORT_SYMBOL(ceph_pagelist_free_reserve);
 134 
 135 /* Create a truncation point. */
 136 void ceph_pagelist_set_cursor(struct ceph_pagelist *pl,
 137                               struct ceph_pagelist_cursor *c)
 138 {
 139         c->pl = pl;
 140         c->page_lru = pl->head.prev;
 141         c->room = pl->room;
 142 }
 143 EXPORT_SYMBOL(ceph_pagelist_set_cursor);
 144 
 145 /* Truncate a pagelist to the given point. Move extra pages to reserve.
 146  * This won't sleep.
 147  * Returns: 0 on success,
 148  *          -EINVAL if the pagelist doesn't match the trunc point pagelist
 149  */
 150 int ceph_pagelist_truncate(struct ceph_pagelist *pl,
 151                            struct ceph_pagelist_cursor *c)
 152 {
 153         struct page *page;
 154 
 155         if (pl != c->pl)
 156                 return -EINVAL;
 157         ceph_pagelist_unmap_tail(pl);
 158         while (pl->head.prev != c->page_lru) {
 159                 page = list_entry(pl->head.prev, struct page, lru);
 160                 /* move from pagelist to reserve */
 161                 list_move_tail(&page->lru, &pl->free_list);
 162                 ++pl->num_pages_free;
 163         }
 164         pl->room = c->room;
 165         if (!list_empty(&pl->head)) {
 166                 page = list_entry(pl->head.prev, struct page, lru);
 167                 pl->mapped_tail = kmap(page);
 168         }
 169         return 0;
 170 }
 171 EXPORT_SYMBOL(ceph_pagelist_truncate);