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_err(struct super_block *sb, const char *func, const char *fmt, ...)
{
	struct va_format vaf;
	va_list args;

	va_start(args, fmt);

	vaf.fmt = fmt;
	vaf.va = &args;

	if (sb)
		pr_err("(device %s): %s: %pV", sb->s_id, func, &vaf);
	else
		pr_err("%s: %pV", func, &vaf);
	va_end(args);
}

void _erofs_info(struct super_block *sb, const char *func, const char *fmt, ...)
{
	struct va_format vaf;
	va_list args;

	va_start(args, fmt);

	vaf.fmt = fmt;
	vaf.va = &args;

	if (sb)
		pr_info("(device %s): %pV", sb->s_id, &vaf);
	else
		pr_info("%pV", &vaf);
	va_end(args);
}

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

	if (len > EROFS_SUPER_OFFSET)
		len -= EROFS_SUPER_OFFSET;

	dsb = kmemdup(sbdata + EROFS_SUPER_OFFSET, len, GFP_KERNEL);
	if (!dsb)
		return -ENOMEM;

	expected_crc = le32_to_cpu(dsb->checksum);
	dsb->checksum = 0;
	/* to allow for x86 boot sectors and other oddities. */
	crc = crc32c(~0, dsb, len);
	kfree(dsb);

	if (crc != expected_crc) {
		erofs_err(sb, "invalid checksum 0x%08x, 0x%08x expected",
			  crc, expected_crc);
		return -EBADMSG;
	}
	return 0;
}

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, EROFS_KMAP);
	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) {
		cnt = min_t(int, sb->s_blocksize - erofs_blkoff(sb, *offset),
			    len - i);
		ptr = erofs_bread(buf, *offset, EROFS_KMAP);
		if (IS_ERR(ptr)) {
			kfree(buffer);
			return ptr;
		}
		memcpy(buffer + i, ptr, cnt);
		*offset += cnt;
	}
	return buffer;
}

#ifndef CONFIG_EROFS_FS_ZIP
static int z_erofs_parse_cfgs(struct super_block *sb,
			      struct erofs_super_block *dsb)
{
	if (!dsb->u1.available_compr_algs)
		return 0;

	erofs_err(sb, "compression disabled, unable to mount compressed EROFS");
	return -EOPNOTSUPP;
}
#endif

static int erofs_init_device(struct erofs_buf *buf, struct super_block *sb,
			     struct erofs_device_info *dif, erofs_off_t *pos)
{
	struct erofs_sb_info *sbi = EROFS_SB(sb);
	struct erofs_fscache *fscache;
	struct erofs_deviceslot *dis;
	struct file *file;

	dis = erofs_read_metabuf(buf, sb, *pos, EROFS_KMAP);
	if (IS_ERR(dis))
		return PTR_ERR(dis);

	if (!sbi->devs->flatdev && !dif->path) {
		if (!dis->tag[0]) {
			erofs_err(sb, "empty device tag @ pos %llu", *pos);
			return -EINVAL;
		}
		dif->path = kmemdup_nul(dis->tag, sizeof(dis->tag), GFP_KERNEL);
		if (!dif->path)
			return -ENOMEM;
	}

	if (erofs_is_fscache_mode(sb)) {
		fscache = erofs_fscache_register_cookie(sb, dif->path