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