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// 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"
/* 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;
loff_t file_end = (i_size_read(inode) - 1) >> PAGE_SHIFT;
int mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
loff_t start_index = target_page->index & ~mask;
loff_t end_index = start_index | mask;
int i, n, 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;
/* Try to grab all the pages covered by the Squashfs block */
for (i = 0, n = start_index; n <= end_index; n++) {
page[i] = (n == target_page->index) ? target_page :
grab_cache_page_nowait(target_page->mapping, n);
if (page[i] == NULL)
continue;
if (PageUptodate(page[i])) {
unlock_page(page[i]);
put_page(page[i]);
continue;
}
i++;
}
pages = i;
/*
* Create a "page actor" which will kmap and kunmap the
* page cache pages appropriately within the decompressor
*/
actor = squashfs_page_actor_init_special(msblk, page, pages, expected);
if (actor == NULL)
goto out;
/* Decompress directly into the page cache buffers */
res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
squashfs_page_actor_free(actor);
if (res < 0)
goto mark_errored;
if (res != expected) {
res = -EIO;
goto mark_errored;
}
/* Last page (if present) may have trailing bytes not filled */
bytes = res % PAGE_SIZE;
if (page[pages - 1]->index == end_index && bytes) {
pageaddr = kmap_local_page(page[pages - 1]);
memset(pageaddr + bytes, 0, PAGE_SIZE - bytes);
kunmap_local(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(page);
return 0;
mark_errored:
/* Decompression failed. 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]);
unlock_page(page[i]);
put_page(page[i]);
}
out:
kfree(page);
return res;
}
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