[linux.git] / fs / squashfs / page_actor.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2013
 * Phillip Lougher <[email protected]>
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include "squashfs_fs_sb.h"
#include "decompressor.h"
#include "page_actor.h"

/*
 * This file contains implementations of page_actor for decompressing into
 * an intermediate buffer, and for decompressing directly into the
 * page cache.
 *
 * Calling code should avoid sleeping between calls to squashfs_first_page()
 * and squashfs_finish_page().
 */

/* Implementation of page_actor for decompressing into intermediate buffer */
static void *cache_first_page(struct squashfs_page_actor *actor)
{
	actor->next_page = 1;
	return actor->buffer[0];
}

static void *cache_next_page(struct squashfs_page_actor *actor)
{
	if (actor->next_page == actor->pages)
		return NULL;

	return actor->buffer[actor->next_page++];
}

static void cache_finish_page(struct squashfs_page_actor *actor)
{
	/* empty */
}

struct squashfs_page_actor *squashfs_page_actor_init(void **buffer,
	int pages, int length)
{
	struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL);

	if (actor == NULL)
		return NULL;

	actor->length = length ? : pages * PAGE_SIZE;
	actor->buffer = buffer;
	actor->pages = pages;
	actor->next_page = 0;
	actor->tmp_buffer = NULL;
	actor->squashfs_first_page = cache_first_page;
	actor->squashfs_next_page = cache_next_page;
	actor->squashfs_finish_page = cache_finish_page;
	return actor;
}

/* Implementation of page_actor for decompressing directly into page cache. */
static void *handle_next_page(struct squashfs_page_actor *actor)
{
	int max_pages = (actor->length + PAGE_SIZE - 1) >> PAGE_SHIFT;

	if (actor->returned_pages == max_pages)
		return NULL;

	if ((actor->next_page == actor->pages) ||
			(actor->next_index != actor->page[actor->next_page]->index)) {
		actor->next_index++;
		actor->returned_pages++;
		actor->last_page = NULL;
		return actor->alloc_buffer ? actor->tmp_buffer : ERR_PTR(-ENOMEM);
	}

	actor->next_index++;
	actor->returned_pages++;
	actor->last_page = actor->page[actor->next_page];
	return actor->pageaddr = kmap_local_page(actor->page[actor->next_page++]);
}

static void *direct_first_page(struct squashfs_page_actor *actor)
{
	return handle_next_page(actor);
}

static void *direct_next_page(struct squashfs_page_actor *actor)
{
	if (actor->pageaddr) {
		kunmap_local(actor->pageaddr);
		actor->pageaddr = NULL;
	}

	return handle_next_page(actor);
}

static void direct_finish_page(struct squashfs_page_actor *actor)
{
	if (actor->pageaddr)
		kunmap_local(actor->pageaddr);
}

struct squashfs_page_actor *squashfs_page_actor_init_special(struct squashfs_sb_info *msblk,
	struct page **page, int pages, int length)
{
	struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL);

	if (actor == NULL)
		return NULL;

	if (msblk->decompressor->alloc_buffer) {
		actor->tmp_buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);

		if (actor->tmp_buffer == NULL) {
			kfree(actor);
			return NULL;
		}
	} else
		actor->tmp_buffer = NULL;

	actor->length = length ? : pages * PAGE_SIZE;
	actor->page = page;
	actor->pages = pages;
	actor->next_page = 0;
	actor->returned_pages = 0;
	actor->next_index = page[0]->index & ~((1 << (msblk->block_log - PAGE_SHIFT)) - 1);
	actor->pageaddr = NULL;
	actor->last_page = NULL;
	actor->alloc_buffer = msblk->decompressor->alloc_buffer;
	actor->squashfs_first_page = direct_first_page;
	actor->squashfs_next_page = direct_next_page;
	actor->squashfs_finish_page = direct_finish_page;
	return actor;
}
Commit	Line	Data
20c8ccb1	1	// SPDX-License-Identifier: GPL-2.0-only
0d455c12 PL	2	/*
	3	* Copyright (c) 2013
	4	* Phillip Lougher <[email protected]>
0d455c12 PL	5	*/
	6
	7	#include <linux/kernel.h>
	8	#include <linux/slab.h>
	9	#include <linux/pagemap.h>
f268eedd PL	10	#include "squashfs_fs_sb.h"
f268eedd PL	11	#include "decompressor.h"
0d455c12 PL	12	#include "page_actor.h"
	13
	14	/*
	15	* This file contains implementations of page_actor for decompressing into
	16	* an intermediate buffer, and for decompressing directly into the
	17	* page cache.
	18	*
	19	* Calling code should avoid sleeping between calls to squashfs_first_page()
	20	* and squashfs_finish_page().
	21	*/
	22
	23	/* Implementation of page_actor for decompressing into intermediate buffer */
	24	static void cache_first_page(struct squashfs_page_actor actor)
	25	{
	26	actor->next_page = 1;
	27	return actor->buffer[0];
	28	}
	29
	30	static void cache_next_page(struct squashfs_page_actor actor)
	31	{
	32	if (actor->next_page == actor->pages)
	33	return NULL;
	34
	35	return actor->buffer[actor->next_page++];
	36	}
	37
	38	static void cache_finish_page(struct squashfs_page_actor *actor)
	39	{
	40	/* empty */
	41	}
	42
	43	struct squashfs_page_actor squashfs_page_actor_init(void *buffer,
	44	int pages, int length)
	45	{
	46	struct squashfs_page_actor actor = kmalloc(sizeof(actor), GFP_KERNEL);
	47
	48	if (actor == NULL)
	49	return NULL;
	50
09cbfeaf	51	actor->length = length ? : pages * PAGE_SIZE;
0d455c12 PL	52	actor->buffer = buffer;
	53	actor->pages = pages;
	54	actor->next_page = 0;
1f13dff0	55	actor->tmp_buffer = NULL;
0d455c12 PL	56	actor->squashfs_first_page = cache_first_page;
	57	actor->squashfs_next_page = cache_next_page;
	58	actor->squashfs_finish_page = cache_finish_page;
	59	return actor;
	60	}
	61
	62	/* Implementation of page_actor for decompressing directly into page cache. */
f268eedd PL	63	static void handle_next_page(struct squashfs_page_actor actor)
	64	{
	65	int max_pages = (actor->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
	66
	67	if (actor->returned_pages == max_pages)
	68	return NULL;
	69
	70	if ((actor->next_page == actor->pages) \|\|
	71	(actor->next_index != actor->page[actor->next_page]->index)) {
f268eedd PL	72	actor->next_index++;
f268eedd PL	73	actor->returned_pages++;
9ef8eb61	74	actor->last_page = NULL;
1f13dff0	75	return actor->alloc_buffer ? actor->tmp_buffer : ERR_PTR(-ENOMEM);
f268eedd PL	76	}
	77
	78	actor->next_index++;
	79	actor->returned_pages++;
9ef8eb61	80	actor->last_page = actor->page[actor->next_page];
f268eedd PL	81	return actor->pageaddr = kmap_local_page(actor->page[actor->next_page++]);
	82	}
	83
0d455c12 PL	84	static void direct_first_page(struct squashfs_page_actor actor)
0d455c12 PL	85	{
f268eedd	86	return handle_next_page(actor);
0d455c12 PL	87	}
	88
	89	static void direct_next_page(struct squashfs_page_actor actor)
	90	{
1f13dff0	91	if (actor->pageaddr) {
f268eedd	92	kunmap_local(actor->pageaddr);
1f13dff0 PL	93	actor->pageaddr = NULL;
1f13dff0 PL	94	}
0d455c12	95
f268eedd	96	return handle_next_page(actor);
0d455c12 PL	97	}
	98
	99	static void direct_finish_page(struct squashfs_page_actor *actor)
	100	{
	101	if (actor->pageaddr)
f268eedd	102	kunmap_local(actor->pageaddr);
0d455c12 PL	103	}
0d455c12 PL	104
f268eedd PL	105	struct squashfs_page_actor squashfs_page_actor_init_special(struct squashfs_sb_info msblk,
f268eedd PL	106	struct page **page, int pages, int length)
0d455c12 PL	107	{
	108	struct squashfs_page_actor actor = kmalloc(sizeof(actor), GFP_KERNEL);
	109
	110	if (actor == NULL)
	111	return NULL;
	112
1f13dff0 PL	113	if (msblk->decompressor->alloc_buffer) {
	114	actor->tmp_buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
	115
	116	if (actor->tmp_buffer == NULL) {
	117	kfree(actor);
	118	return NULL;
	119	}
	120	} else
	121	actor->tmp_buffer = NULL;
	122
09cbfeaf	123	actor->length = length ? : pages * PAGE_SIZE;
0d455c12 PL	124	actor->page = page;
	125	actor->pages = pages;
	126	actor->next_page = 0;
f268eedd PL	127	actor->returned_pages = 0;
f268eedd PL	128	actor->next_index = page[0]->index & ~((1 << (msblk->block_log - PAGE_SHIFT)) - 1);
0d455c12	129	actor->pageaddr = NULL;
9ef8eb61	130	actor->last_page = NULL;
f268eedd	131	actor->alloc_buffer = msblk->decompressor->alloc_buffer;
0d455c12 PL	132	actor->squashfs_first_page = direct_first_page;
	133	actor->squashfs_next_page = direct_next_page;
	134	actor->squashfs_finish_page = direct_finish_page;
	135	return actor;
	136	}