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![Yan, Zheng](/assets/img/avatar_default.png)
this allow pagelist to present data that may be sent multiple times. Signed-off-by: Yan, Zheng <zyan@redhat.com> Reviewed-by: Sage Weil <sage@redhat.com>
150 lines
3.6 KiB
C
150 lines
3.6 KiB
C
#include <linux/module.h>
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#include <linux/gfp.h>
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#include <linux/slab.h>
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#include <linux/pagemap.h>
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#include <linux/highmem.h>
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#include <linux/ceph/pagelist.h>
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static void ceph_pagelist_unmap_tail(struct ceph_pagelist *pl)
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{
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if (pl->mapped_tail) {
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struct page *page = list_entry(pl->head.prev, struct page, lru);
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kunmap(page);
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pl->mapped_tail = NULL;
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}
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}
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void ceph_pagelist_release(struct ceph_pagelist *pl)
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{
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if (!atomic_dec_and_test(&pl->refcnt))
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return;
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ceph_pagelist_unmap_tail(pl);
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while (!list_empty(&pl->head)) {
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struct page *page = list_first_entry(&pl->head, struct page,
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lru);
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list_del(&page->lru);
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__free_page(page);
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}
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ceph_pagelist_free_reserve(pl);
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kfree(pl);
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}
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EXPORT_SYMBOL(ceph_pagelist_release);
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static int ceph_pagelist_addpage(struct ceph_pagelist *pl)
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{
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struct page *page;
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if (!pl->num_pages_free) {
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page = __page_cache_alloc(GFP_NOFS);
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} else {
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page = list_first_entry(&pl->free_list, struct page, lru);
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list_del(&page->lru);
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--pl->num_pages_free;
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}
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if (!page)
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return -ENOMEM;
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pl->room += PAGE_SIZE;
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ceph_pagelist_unmap_tail(pl);
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list_add_tail(&page->lru, &pl->head);
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pl->mapped_tail = kmap(page);
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return 0;
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}
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int ceph_pagelist_append(struct ceph_pagelist *pl, const void *buf, size_t len)
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{
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while (pl->room < len) {
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size_t bit = pl->room;
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int ret;
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memcpy(pl->mapped_tail + (pl->length & ~PAGE_CACHE_MASK),
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buf, bit);
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pl->length += bit;
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pl->room -= bit;
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buf += bit;
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len -= bit;
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ret = ceph_pagelist_addpage(pl);
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if (ret)
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return ret;
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}
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memcpy(pl->mapped_tail + (pl->length & ~PAGE_CACHE_MASK), buf, len);
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pl->length += len;
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pl->room -= len;
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return 0;
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}
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EXPORT_SYMBOL(ceph_pagelist_append);
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/* Allocate enough pages for a pagelist to append the given amount
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* of data without without allocating.
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* Returns: 0 on success, -ENOMEM on error.
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*/
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int ceph_pagelist_reserve(struct ceph_pagelist *pl, size_t space)
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{
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if (space <= pl->room)
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return 0;
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space -= pl->room;
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space = (space + PAGE_SIZE - 1) >> PAGE_SHIFT; /* conv to num pages */
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while (space > pl->num_pages_free) {
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struct page *page = __page_cache_alloc(GFP_NOFS);
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if (!page)
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return -ENOMEM;
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list_add_tail(&page->lru, &pl->free_list);
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++pl->num_pages_free;
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}
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return 0;
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}
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EXPORT_SYMBOL(ceph_pagelist_reserve);
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/* Free any pages that have been preallocated. */
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int ceph_pagelist_free_reserve(struct ceph_pagelist *pl)
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{
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while (!list_empty(&pl->free_list)) {
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struct page *page = list_first_entry(&pl->free_list,
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struct page, lru);
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list_del(&page->lru);
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__free_page(page);
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--pl->num_pages_free;
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}
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BUG_ON(pl->num_pages_free);
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return 0;
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}
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EXPORT_SYMBOL(ceph_pagelist_free_reserve);
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/* Create a truncation point. */
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void ceph_pagelist_set_cursor(struct ceph_pagelist *pl,
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struct ceph_pagelist_cursor *c)
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{
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c->pl = pl;
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c->page_lru = pl->head.prev;
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c->room = pl->room;
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}
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EXPORT_SYMBOL(ceph_pagelist_set_cursor);
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/* Truncate a pagelist to the given point. Move extra pages to reserve.
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* This won't sleep.
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* Returns: 0 on success,
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* -EINVAL if the pagelist doesn't match the trunc point pagelist
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*/
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int ceph_pagelist_truncate(struct ceph_pagelist *pl,
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struct ceph_pagelist_cursor *c)
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{
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struct page *page;
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if (pl != c->pl)
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return -EINVAL;
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ceph_pagelist_unmap_tail(pl);
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while (pl->head.prev != c->page_lru) {
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page = list_entry(pl->head.prev, struct page, lru);
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/* move from pagelist to reserve */
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list_move_tail(&page->lru, &pl->free_list);
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++pl->num_pages_free;
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}
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pl->room = c->room;
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if (!list_empty(&pl->head)) {
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page = list_entry(pl->head.prev, struct page, lru);
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pl->mapped_tail = kmap(page);
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}
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return 0;
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}
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EXPORT_SYMBOL(ceph_pagelist_truncate);
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