[mirror_ubuntu-jammy-kernel.git] / fs / squashfs / file_direct.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2013
 * Phillip Lougher <phillip@squashfs.org.uk>
 */

#include <linux/fs.h>
#include <linux/vfs.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/pagemap.h>
#include <linux/mutex.h>

#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
#include "squashfs_fs_i.h"
#include "squashfs.h"
#include "page_actor.h"

static int squashfs_read_cache(struct page *target_page, u64 block, int bsize,
	int pages, struct page **page, int bytes);

/* Read separately compressed datablock directly into page cache */
int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
	int expected)

{
	struct inode *inode = target_page->mapping->host;
	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;

	int file_end = (i_size_read(inode) - 1) >> PAGE_SHIFT;
	int mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
	int start_index = target_page->index & ~mask;
	int end_index = start_index | mask;
	int i, n, pages, missing_pages, bytes, res = -ENOMEM;
	struct page **page;
	struct squashfs_page_actor *actor;
	void *pageaddr;

	if (end_index > file_end)
		end_index = file_end;

	pages = end_index - start_index + 1;

	page = kmalloc_array(pages, sizeof(void *), GFP_KERNEL);
	if (page == NULL)
		return res;

	/*
	 * Create a "page actor" which will kmap and kunmap the
	 * page cache pages appropriately within the decompressor
	 */
	actor = squashfs_page_actor_init_special(page, pages, 0);
	if (actor == NULL)
		goto out;

	/* Try to grab all the pages covered by the Squashfs block */
	for (missing_pages = 0, i = 0, n = start_index; i < pages; i++, n++) {
		page[i] = (n == target_page->index) ? target_page :
			grab_cache_page_nowait(target_page->mapping, n);

		if (page[i] == NULL) {
			missing_pages++;
			continue;
		}

		if (PageUptodate(page[i])) {
			unlock_page(page[i]);
			put_page(page[i]);
			page[i] = NULL;
			missing_pages++;
		}
	}

	if (missing_pages) {
		/*
		 * Couldn't get one or more pages, this page has either
		 * been VM reclaimed, but others are still in the page cache
		 * and uptodate, or we're racing with another thread in
		 * squashfs_readpage also trying to grab them.  Fall back to
		 * using an intermediate buffer.
		 */
		res = squashfs_read_cache(target_page, block, bsize, pages,
							page, expected);
		if (res < 0)
			goto mark_errored;

		goto out;
	}

	/* Decompress directly into the page cache buffers */
	res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
	if (res < 0)
		goto mark_errored;

	if (res != expected) {
		res = -EIO;
		goto mark_errored;
	}

	/* Last page may have trailing bytes not filled */
	bytes = res % PAGE_SIZE;
	if (bytes) {
		pageaddr = kmap_atomic(page[pages - 1]);
		memset(pageaddr + bytes, 0, PAGE_SIZE - bytes);
		kunmap_atomic(pageaddr);
	}

	/* Mark pages as uptodate, unlock and release */
	for (i = 0; i < pages; i++) {
		flush_dcache_page(page[i]);
		SetPageUptodate(page[i]);
		unlock_page(page[i]);
		if (page[i] != target_page)
			put_page(page[i]);
	}

	kfree(actor);
	kfree(page);

	return 0;

mark_errored:
	/* Decompression failed, mark pages as errored.  Target_page is
	 * dealt with by the caller
	 */
	for (i = 0; i < pages; i++) {
		if (page[i] == NULL || page[i] == target_page)
			continue;
		flush_dcache_page(page[i]);
		SetPageError(page[i]);
		unlock_page(page[i]);
		put_page(page[i]);
	}

out:
	kfree(actor);
	kfree(page);
	return res;
}


static int squashfs_read_cache(struct page *target_page, u64 block, int bsize,
	int pages, struct page **page, int bytes)
{
	struct inode *i = target_page->mapping->host;
	struct squashfs_cache_entry *buffer = squashfs_get_datablock(i->i_sb,
						 block, bsize);
	int res = buffer->error, n, offset = 0;

	if (res) {
		ERROR("Unable to read page, block %llx, size %x\n", block,
			bsize);
		goto out;
	}

	for (n = 0; n < pages && bytes > 0; n++,
			bytes -= PAGE_SIZE, offset += PAGE_SIZE) {
		int avail = min_t(int, bytes, PAGE_SIZE);

		if (page[n] == NULL)
			continue;

		squashfs_fill_page(page[n], buffer, offset, avail);
		unlock_page(page[n]);
		if (page[n] != target_page)
			put_page(page[n]);
	}

out:
	squashfs_cache_put(buffer);
	return res;
}
Commit	Line	Data
20c8ccb1	1	// SPDX-License-Identifier: GPL-2.0-only
0d455c12 PL	2	/*
	3	* Copyright (c) 2013
	4	* Phillip Lougher <phillip@squashfs.org.uk>
0d455c12 PL	5	*/
	6
	7	#include <linux/fs.h>
	8	#include <linux/vfs.h>
	9	#include <linux/kernel.h>
	10	#include <linux/slab.h>
	11	#include <linux/string.h>
	12	#include <linux/pagemap.h>
	13	#include <linux/mutex.h>
	14
	15	#include "squashfs_fs.h"
	16	#include "squashfs_fs_sb.h"
	17	#include "squashfs_fs_i.h"
	18	#include "squashfs.h"
	19	#include "page_actor.h"
	20
	21	static int squashfs_read_cache(struct page *target_page, u64 block, int bsize,
a3f94cb9	22	int pages, struct page **page, int bytes);
0d455c12 PL	23
0d455c12 PL	24	/* Read separately compressed datablock directly into page cache */
a3f94cb9 PL	25	int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
a3f94cb9 PL	26	int expected)
0d455c12 PL	27
	28	{
	29	struct inode *inode = target_page->mapping->host;
	30	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
	31
09cbfeaf KS	32	int file_end = (i_size_read(inode) - 1) >> PAGE_SHIFT;
09cbfeaf KS	33	int mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
0d455c12 PL	34	int start_index = target_page->index & ~mask;
	35	int end_index = start_index \| mask;
	36	int i, n, pages, missing_pages, bytes, res = -ENOMEM;
	37	struct page **page;
	38	struct squashfs_page_actor *actor;
	39	void *pageaddr;
	40
	41	if (end_index > file_end)
	42	end_index = file_end;
	43
	44	pages = end_index - start_index + 1;
	45
14694888	46	page = kmalloc_array(pages, sizeof(void *), GFP_KERNEL);
0d455c12 PL	47	if (page == NULL)
	48	return res;
	49
	50	/*
	51	* Create a "page actor" which will kmap and kunmap the
	52	* page cache pages appropriately within the decompressor
	53	*/
	54	actor = squashfs_page_actor_init_special(page, pages, 0);
	55	if (actor == NULL)
	56	goto out;
	57
	58	/* Try to grab all the pages covered by the Squashfs block */
	59	for (missing_pages = 0, i = 0, n = start_index; i < pages; i++, n++) {
	60	page[i] = (n == target_page->index) ? target_page :
	61	grab_cache_page_nowait(target_page->mapping, n);
	62
	63	if (page[i] == NULL) {
	64	missing_pages++;
	65	continue;
	66	}
	67
	68	if (PageUptodate(page[i])) {
	69	unlock_page(page[i]);
09cbfeaf	70	put_page(page[i]);
0d455c12 PL	71	page[i] = NULL;
	72	missing_pages++;
	73	}
	74	}
	75
	76	if (missing_pages) {
	77	/*
	78	* Couldn't get one or more pages, this page has either
	79	* been VM reclaimed, but others are still in the page cache
	80	* and uptodate, or we're racing with another thread in
	81	* squashfs_readpage also trying to grab them. Fall back to
	82	* using an intermediate buffer.
	83	*/
	84	res = squashfs_read_cache(target_page, block, bsize, pages,
a3f94cb9	85	page, expected);
6d565409 PL	86	if (res < 0)
	87	goto mark_errored;
	88
0d455c12 PL	89	goto out;
	90	}
	91
	92	/* Decompress directly into the page cache buffers */
	93	res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
	94	if (res < 0)
	95	goto mark_errored;
	96
a3f94cb9 PL	97	if (res != expected) {
	98	res = -EIO;
	99	goto mark_errored;
	100	}
	101
0d455c12	102	/* Last page may have trailing bytes not filled */
09cbfeaf	103	bytes = res % PAGE_SIZE;
0d455c12 PL	104	if (bytes) {
0d455c12 PL	105	pageaddr = kmap_atomic(page[pages - 1]);
09cbfeaf	106	memset(pageaddr + bytes, 0, PAGE_SIZE - bytes);
0d455c12 PL	107	kunmap_atomic(pageaddr);
	108	}
	109
	110	/* Mark pages as uptodate, unlock and release */
	111	for (i = 0; i < pages; i++) {
	112	flush_dcache_page(page[i]);
	113	SetPageUptodate(page[i]);
	114	unlock_page(page[i]);
	115	if (page[i] != target_page)
09cbfeaf	116	put_page(page[i]);
0d455c12 PL	117	}
	118
	119	kfree(actor);
	120	kfree(page);
	121
	122	return 0;
	123
	124	mark_errored:
	125	/* Decompression failed, mark pages as errored. Target_page is
	126	* dealt with by the caller
	127	*/
	128	for (i = 0; i < pages; i++) {
6d565409	129	if (page[i] == NULL \|\| page[i] == target_page)
0d455c12 PL	130	continue;
	131	flush_dcache_page(page[i]);
	132	SetPageError(page[i]);
	133	unlock_page(page[i]);
09cbfeaf	134	put_page(page[i]);
0d455c12 PL	135	}
	136
	137	out:
	138	kfree(actor);
	139	kfree(page);
	140	return res;
	141	}
	142
	143
	144	static int squashfs_read_cache(struct page *target_page, u64 block, int bsize,
a3f94cb9	145	int pages, struct page **page, int bytes)
0d455c12 PL	146	{
	147	struct inode *i = target_page->mapping->host;
	148	struct squashfs_cache_entry *buffer = squashfs_get_datablock(i->i_sb,
	149	block, bsize);
a3f94cb9	150	int res = buffer->error, n, offset = 0;
0d455c12 PL	151
	152	if (res) {
	153	ERROR("Unable to read page, block %llx, size %x\n", block,
	154	bsize);
	155	goto out;
	156	}
	157
	158	for (n = 0; n < pages && bytes > 0; n++,
09cbfeaf KS	159	bytes -= PAGE_SIZE, offset += PAGE_SIZE) {
09cbfeaf KS	160	int avail = min_t(int, bytes, PAGE_SIZE);
0d455c12 PL	161
	162	if (page[n] == NULL)
	163	continue;
	164
cdbb65c4	165	squashfs_fill_page(page[n], buffer, offset, avail);
0d455c12 PL	166	unlock_page(page[n]);
0d455c12 PL	167	if (page[n] != target_page)
09cbfeaf	168	put_page(page[n]);
0d455c12 PL	169	}
	170
	171	out:
	172	squashfs_cache_put(buffer);
	173	return res;
	174	}