![Kirill A. Shutemov](/assets/img/avatar_default.png)
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
151 lines
3.6 KiB
C
151 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_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_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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