squashfs: add option to panic on errors

Add an errors=panic mount option to make squashfs trigger a panic when
errors are encountered, similar to several other filesystems.  This allows
a kernel dump to be saved using which the corruption can be analysed and
debugged.

Inspired by a pre-fs_context patch by Anton Eliasson.

Link: https://lkml.kernel.org/r/20210527125019.14511-1-vincent.whitchurch@axis.com
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vincent Whitchurch 2021-06-28 19:33:55 -07:00 committed by Linus Torvalds
parent d98e4d9541
commit 10dde05b89
3 changed files with 91 additions and 1 deletions

View file

@ -226,8 +226,11 @@ int squashfs_read_data(struct super_block *sb, u64 index, int length,
bio_free_pages(bio);
bio_put(bio);
out:
if (res < 0)
if (res < 0) {
ERROR("Failed to read block 0x%llx: %d\n", index, res);
if (msblk->panic_on_errors)
panic("squashfs read failed");
}
return res;
}

View file

@ -65,5 +65,6 @@ struct squashfs_sb_info {
unsigned int fragments;
int xattr_ids;
unsigned int ids;
bool panic_on_errors;
};
#endif

View file

@ -18,9 +18,11 @@
#include <linux/fs.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include <linux/vfs.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/seq_file.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/module.h>
@ -37,6 +39,51 @@
static struct file_system_type squashfs_fs_type;
static const struct super_operations squashfs_super_ops;
enum Opt_errors {
Opt_errors_continue,
Opt_errors_panic,
};
enum squashfs_param {
Opt_errors,
};
struct squashfs_mount_opts {
enum Opt_errors errors;
};
static const struct constant_table squashfs_param_errors[] = {
{"continue", Opt_errors_continue },
{"panic", Opt_errors_panic },
{}
};
static const struct fs_parameter_spec squashfs_fs_parameters[] = {
fsparam_enum("errors", Opt_errors, squashfs_param_errors),
{}
};
static int squashfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
struct squashfs_mount_opts *opts = fc->fs_private;
struct fs_parse_result result;
int opt;
opt = fs_parse(fc, squashfs_fs_parameters, param, &result);
if (opt < 0)
return opt;
switch (opt) {
case Opt_errors:
opts->errors = result.uint_32;
break;
default:
return -EINVAL;
}
return 0;
}
static const struct squashfs_decompressor *supported_squashfs_filesystem(
struct fs_context *fc,
short major, short minor, short id)
@ -67,6 +114,7 @@ static const struct squashfs_decompressor *supported_squashfs_filesystem(
static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
{
struct squashfs_mount_opts *opts = fc->fs_private;
struct squashfs_sb_info *msblk;
struct squashfs_super_block *sblk = NULL;
struct inode *root;
@ -85,6 +133,8 @@ static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
}
msblk = sb->s_fs_info;
msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
msblk->devblksize_log2 = ffz(~msblk->devblksize);
@ -350,18 +400,52 @@ static int squashfs_get_tree(struct fs_context *fc)
static int squashfs_reconfigure(struct fs_context *fc)
{
struct super_block *sb = fc->root->d_sb;
struct squashfs_sb_info *msblk = sb->s_fs_info;
struct squashfs_mount_opts *opts = fc->fs_private;
sync_filesystem(fc->root->d_sb);
fc->sb_flags |= SB_RDONLY;
msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
return 0;
}
static void squashfs_free_fs_context(struct fs_context *fc)
{
kfree(fc->fs_private);
}
static const struct fs_context_operations squashfs_context_ops = {
.get_tree = squashfs_get_tree,
.free = squashfs_free_fs_context,
.parse_param = squashfs_parse_param,
.reconfigure = squashfs_reconfigure,
};
static int squashfs_show_options(struct seq_file *s, struct dentry *root)
{
struct super_block *sb = root->d_sb;
struct squashfs_sb_info *msblk = sb->s_fs_info;
if (msblk->panic_on_errors)
seq_puts(s, ",errors=panic");
else
seq_puts(s, ",errors=continue");
return 0;
}
static int squashfs_init_fs_context(struct fs_context *fc)
{
struct squashfs_mount_opts *opts;
opts = kzalloc(sizeof(*opts), GFP_KERNEL);
if (!opts)
return -ENOMEM;
fc->fs_private = opts;
fc->ops = &squashfs_context_ops;
return 0;
}
@ -481,6 +565,7 @@ static struct file_system_type squashfs_fs_type = {
.owner = THIS_MODULE,
.name = "squashfs",
.init_fs_context = squashfs_init_fs_context,
.parameters = squashfs_fs_parameters,
.kill_sb = kill_block_super,
.fs_flags = FS_REQUIRES_DEV
};
@ -491,6 +576,7 @@ static const struct super_operations squashfs_super_ops = {
.free_inode = squashfs_free_inode,
.statfs = squashfs_statfs,
.put_super = squashfs_put_super,
.show_options = squashfs_show_options,
};
module_init(init_squashfs_fs);