mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-09-21 12:11:49 +08:00
84e0e03b30
In the recent work to remove page->index, a sanity check that ensured all the readhead pages were covered by the Squashfs data block was removed [1]. To avoid any regression, this commit adds the sanity check back in an equivalent way. Namely the page actor will now return error if any pages are unused after completion. [1] https://lore.kernel.org/all/20240818235847.170468-3-phillip@squashfs.org.uk/ -- Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Link: https://lore.kernel.org/r/20240822233106.121522-1-phillip@squashfs.org.uk V3: last_page should be actor->last_page Signed-off-by: Christian Brauner <brauner@kernel.org>
125 lines
2.9 KiB
C
125 lines
2.9 KiB
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"
|
|
|
|
/* Read separately compressed datablock directly into page cache */
|
|
int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
|
|
int expected)
|
|
|
|
{
|
|
struct folio *folio = page_folio(target_page);
|
|
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 = folio->index & ~mask;
|
|
loff_t end_index = start_index | mask;
|
|
int i, n, pages, bytes, res = -ENOMEM;
|
|
struct page **page, *last_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 == folio->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,
|
|
start_index << PAGE_SHIFT);
|
|
if (actor == NULL)
|
|
goto out;
|
|
|
|
/* Decompress directly into the page cache buffers */
|
|
res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor);
|
|
|
|
last_page = squashfs_page_actor_free(actor);
|
|
|
|
if (res < 0)
|
|
goto mark_errored;
|
|
|
|
if (res != expected || IS_ERR(last_page)) {
|
|
res = -EIO;
|
|
goto mark_errored;
|
|
}
|
|
|
|
/* Last page (if present) may have trailing bytes not filled */
|
|
bytes = res % PAGE_SIZE;
|
|
if (end_index == file_end && last_page && bytes) {
|
|
pageaddr = kmap_local_page(last_page);
|
|
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;
|
|
}
|