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); 172