page_actor.c
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/*
* Copyright (c) 2013
* Phillip Lougher <phillip@squashfs.org.uk>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/buffer_head.h>
#include "page_actor.h"
struct squashfs_page_actor *squashfs_page_actor_init(struct page **page,
int pages, int length, void (*release_pages)(struct page **, int, int))
{
struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL);
if (actor == NULL)
return NULL;
actor->length = length ? : pages * PAGE_SIZE;
actor->page = page;
actor->pages = pages;
actor->next_page = 0;
actor->pageaddr = NULL;
actor->release_pages = release_pages;
return actor;
}
void squashfs_page_actor_free(struct squashfs_page_actor *actor, int error)
{
if (!actor)
return;
if (actor->release_pages)
actor->release_pages(actor->page, actor->pages, error);
kfree(actor);
}
void squashfs_actor_to_buf(struct squashfs_page_actor *actor, void *buf,
int length)
{
void *pageaddr;
int pos = 0, avail, i;
for (i = 0; i < actor->pages && pos < length; ++i) {
avail = min_t(int, length - pos, PAGE_SIZE);
if (actor->page[i]) {
pageaddr = kmap_atomic(actor->page[i]);
memcpy(buf + pos, pageaddr, avail);
kunmap_atomic(pageaddr);
}
pos += avail;
}
}
void squashfs_buf_to_actor(void *buf, struct squashfs_page_actor *actor,
int length)
{
void *pageaddr;
int pos = 0, avail, i;
for (i = 0; i < actor->pages && pos < length; ++i) {
avail = min_t(int, length - pos, PAGE_SIZE);
if (actor->page[i]) {
pageaddr = kmap_atomic(actor->page[i]);
memcpy(pageaddr, buf + pos, avail);
kunmap_atomic(pageaddr);
}
pos += avail;
}
}
void squashfs_bh_to_actor(struct buffer_head **bh, int nr_buffers,
struct squashfs_page_actor *actor, int offset, int length, int blksz)
{
void *kaddr = NULL;
int bytes = 0, pgoff = 0, b = 0, p = 0, avail, i;
while (bytes < length) {
if (actor->page[p]) {
kaddr = kmap_atomic(actor->page[p]);
while (pgoff < PAGE_SIZE && bytes < length) {
avail = min_t(int, blksz - offset,
PAGE_SIZE - pgoff);
memcpy(kaddr + pgoff, bh[b]->b_data + offset,
avail);
pgoff += avail;
bytes += avail;
offset = (offset + avail) % blksz;
if (!offset) {
put_bh(bh[b]);
++b;
}
}
kunmap_atomic(kaddr);
pgoff = 0;
} else {
for (i = 0; i < PAGE_SIZE / blksz; ++i) {
if (bh[b])
put_bh(bh[b]);
++b;
}
bytes += PAGE_SIZE;
}
++p;
}
}
void squashfs_bh_to_buf(struct buffer_head **bh, int nr_buffers, void *buf,
int offset, int length, int blksz)
{
int i, avail, bytes = 0;
for (i = 0; i < nr_buffers && bytes < length; ++i) {
avail = min_t(int, length - bytes, blksz - offset);
if (bh[i]) {
memcpy(buf + bytes, bh[i]->b_data + offset, avail);
put_bh(bh[i]);
}
bytes += avail;
offset = 0;
}
}
void free_page_array(struct page **page, int nr_pages)
{
int i;
for (i = 0; i < nr_pages; ++i)
__free_page(page[i]);
kfree(page);
}
struct page **alloc_page_array(int nr_pages, int gfp_mask)
{
int i;
struct page **page;
page = kcalloc(nr_pages, sizeof(struct page *), gfp_mask);
if (!page)
return NULL;
for (i = 0; i < nr_pages; ++i) {
page[i] = alloc_page(gfp_mask);
if (!page[i]) {
free_page_array(page, i);
return NULL;
}
}
return page;
}