Revision 082cd4ec240b8734a82a89ffb890216ac98fec68 authored by Ye Bin on 06 May 2021, 14:10:42 UTC, committed by Theodore Ts'o on 06 June 2021, 14:09:55 UTC
We got follow bug_on when run fsstress with injecting IO fault:
[130747.323114] kernel BUG at fs/ext4/extents_status.c:762!
[130747.323117] Internal error: Oops - BUG: 0 [#1] SMP
......
[130747.334329] Call trace:
[130747.334553]  ext4_es_cache_extent+0x150/0x168 [ext4]
[130747.334975]  ext4_cache_extents+0x64/0xe8 [ext4]
[130747.335368]  ext4_find_extent+0x300/0x330 [ext4]
[130747.335759]  ext4_ext_map_blocks+0x74/0x1178 [ext4]
[130747.336179]  ext4_map_blocks+0x2f4/0x5f0 [ext4]
[130747.336567]  ext4_mpage_readpages+0x4a8/0x7a8 [ext4]
[130747.336995]  ext4_readpage+0x54/0x100 [ext4]
[130747.337359]  generic_file_buffered_read+0x410/0xae8
[130747.337767]  generic_file_read_iter+0x114/0x190
[130747.338152]  ext4_file_read_iter+0x5c/0x140 [ext4]
[130747.338556]  __vfs_read+0x11c/0x188
[130747.338851]  vfs_read+0x94/0x150
[130747.339110]  ksys_read+0x74/0xf0

This patch's modification is according to Jan Kara's suggestion in:
https://patchwork.ozlabs.org/project/linux-ext4/patch/20210428085158.3728201-1-yebin10@huawei.com/
"I see. Now I understand your patch. Honestly, seeing how fragile is trying
to fix extent tree after split has failed in the middle, I would probably
go even further and make sure we fix the tree properly in case of ENOSPC
and EDQUOT (those are easily user triggerable).  Anything else indicates a
HW problem or fs corruption so I'd rather leave the extent tree as is and
don't try to fix it (which also means we will not create overlapping
extents)."

Cc: stable@kernel.org
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210506141042.3298679-1-yebin10@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
1 parent b45f189
Raw File
rodata_test.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * rodata_test.c: functional test for mark_rodata_ro function
 *
 * (C) Copyright 2008 Intel Corporation
 * Author: Arjan van de Ven <arjan@linux.intel.com>
 */
#define pr_fmt(fmt) "rodata_test: " fmt

#include <linux/rodata_test.h>
#include <linux/uaccess.h>
#include <asm/sections.h>

static const int rodata_test_data = 0xC3;

void rodata_test(void)
{
	unsigned long start, end;
	int zero = 0;

	/* test 1: read the value */
	/* If this test fails, some previous testrun has clobbered the state */
	if (!rodata_test_data) {
		pr_err("test 1 fails (start data)\n");
		return;
	}

	/* test 2: write to the variable; this should fault */
	if (!copy_to_kernel_nofault((void *)&rodata_test_data,
				(void *)&zero, sizeof(zero))) {
		pr_err("test data was not read only\n");
		return;
	}

	/* test 3: check the value hasn't changed */
	if (rodata_test_data == zero) {
		pr_err("test data was changed\n");
		return;
	}

	/* test 4: check if the rodata section is PAGE_SIZE aligned */
	start = (unsigned long)__start_rodata;
	end = (unsigned long)__end_rodata;
	if (start & (PAGE_SIZE - 1)) {
		pr_err("start of .rodata is not page size aligned\n");
		return;
	}
	if (end & (PAGE_SIZE - 1)) {
		pr_err("end of .rodata is not page size aligned\n");
		return;
	}

	pr_info("all tests were successful\n");
}
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