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