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