Commit 10dde05b authored by Vincent Whitchurch's avatar Vincent Whitchurch Committed by Linus Torvalds
Browse files

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: default avatarVincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: default avatarPhillip Lougher <phillip@squashfs.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d98e4d95

fs/squashfs/block.c

+4 −1
Original line number Diff line number Diff line
@@ -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;

}

fs/squashfs/squashfs_fs_sb.h

+1 −0
Original line number Diff line number Diff line
@@ -65,5 +65,6 @@ struct squashfs_sb_info { 
	unsigned int				fragments;

	int					xattr_ids;

	unsigned int				ids;

	bool					panic_on_errors;

};

#endif

fs/squashfs/super.c

+86 −0
Original line number Diff line number Diff line
@@ -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);