path: root/fs/erofs/super.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2017-2018 HUAWEI, Inc.
 *             https://www.huawei.com/
 * Copyright (C) 2021, Alibaba Cloud
 */
#include <linux/statfs.h>
#include <linux/seq_file.h>
#include <linux/crc32c.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include <linux/exportfs.h>
#include <linux/backing-dev.h>
#include "xattr.h"

#define CREATE_TRACE_POINTS
#include <trace/events/erofs.h>

static struct kmem_cache *erofs_inode_cachep __read_mostly;

void _erofs_printk(struct super_block *sb, const char *fmt, ...)
{
	struct va_format vaf;
	va_list args;
	int level;

	va_start(args, fmt);

	level = printk_get_level(fmt);
	vaf.fmt = printk_skip_level(fmt);
	vaf.va = &args;
	if (sb)
		printk("%c%cerofs (device %s): %pV",
				KERN_SOH_ASCII, level, sb->s_id, &vaf);
	else
		printk("%c%cerofs: %pV", KERN_SOH_ASCII, level, &vaf);
	va_end(args);
}

static int erofs_superblock_csum_verify(struct super_block *sb, void *sbdata)
{
	struct erofs_super_block *dsb = sbdata + EROFS_SUPER_OFFSET;
	u32 len = 1 << EROFS_SB(sb)->blkszbits, crc;

	if (len > EROFS_SUPER_OFFSET)
		len -= EROFS_SUPER_OFFSET;
	len -= offsetof(struct erofs_super_block, checksum) +
			sizeof(dsb->checksum);

	/* skip .magic(pre-verified) and .checksum(0) fields */
	crc = crc32c(0x5045B54A, (&dsb->checksum) + 1, len);
	if (crc == le32_to_cpu(dsb->checksum))
		return 0;
	erofs_err(sb, "invalid checksum 0x%08x, 0x%08x expected",
		  crc, le32_to_cpu(dsb->checksum));
	return -EBADMSG;
}

static void erofs_inode_init_once(void *ptr)
{
	struct erofs_inode *vi = ptr;

	inode_init_once(&vi->vfs_inode);
}

static struct inode *erofs_alloc_inode(struct super_block *sb)
{
	struct erofs_inode *vi =
		alloc_inode_sb(sb, erofs_inode_cachep, GFP_KERNEL);

	if (!vi)
		return NULL;

	/* zero out everything except vfs_inode */
	memset(vi, 0, offsetof(struct erofs_inode, vfs_inode));
	return &vi->vfs_inode;
}

static void erofs_free_inode(struct inode *inode)
{
	struct erofs_inode *vi = EROFS_I(inode);

	if (inode->i_op == &erofs_fast_symlink_iops)
		kfree(inode->i_link);
	kfree(vi->xattr_shared_xattrs);
	kmem_cache_free(erofs_inode_cachep, vi);
}

/* read variable-sized metadata, offset will be aligned by 4-byte */
void *erofs_read_metadata(struct super_block *sb, struct erofs_buf *buf,
			  erofs_off_t *offset, int *lengthp)
{
	u8 *buffer, *ptr;
	int len, i, cnt;

	*offset = round_up(*offset, 4);
	ptr = erofs_bread(buf, *offset, true);
	if (IS_ERR(ptr))
		return ptr;

	len = le16_to_cpu(*(__le16 *)ptr);
	if (!len)
		len = U16_MAX + 1;
	buffer = kmalloc(len, GFP_KERNEL);
	if (!buffer)
		return ERR_PTR(-ENOMEM);
	*offset += sizeof(__le16);
	*lengthp = len;

	for (i = 0; i < len; i += cnt