linux/fs/squashfs/file_direct.c
Phillip Lougher 1f13dff09f squashfs: don't call kmalloc in decompressors
The decompressors may be called while in an atomic section.  So move the
kmalloc() out of this path, and into the "page actor" init function.

This fixes a regression introduced by commit
f268eedddf ("squashfs: extend "page actor" to handle missing pages")

Link: https://lkml.kernel.org/r/20220822215430.15933-1-phillip@squashfs.org.uk
Fixes: f268eedddf ("squashfs: extend "page actor" to handle missing pages")
Reported-by: Chris Murphy <lists@colorremedies.com>
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-08-28 14:02:45 -07:00

125 lines
2.8 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 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, 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, 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(page);
return res;
}