staging: erofs: add inode operations

// SPDX-License-Identifier: GPL-2.0

/*

 * linux/drivers/staging/erofs/inode.c

 *

 * Copyright (C) 2017-2018 HUAWEI, Inc.

 *             http://www.huawei.com/

 * Created by Gao Xiang <gaoxiang25@huawei.com>

 *

 * This file is subject to the terms and conditions of the GNU General Public

 * License.  See the file COPYING in the main directory of the Linux

 * distribution for more details.

 */

#include "internal.h"

/* no locking */

static int read_inode(struct inode *inode, void *data)

{

	struct erofs_vnode *vi = EROFS_V(inode);

	struct erofs_inode_v1 *v1 = data;

	const unsigned advise = le16_to_cpu(v1->i_advise);

	vi->data_mapping_mode = __inode_data_mapping(advise);

	if (unlikely(vi->data_mapping_mode >= EROFS_INODE_LAYOUT_MAX)) {

		errln("unknown data mapping mode %u of nid %llu",

			vi->data_mapping_mode, vi->nid);

		DBG_BUGON(1);

		return -EIO;

	}

	if (__inode_version(advise) == EROFS_INODE_LAYOUT_V2) {

		struct erofs_inode_v2 *v2 = data;

		vi->inode_isize = sizeof(struct erofs_inode_v2);

		vi->xattr_isize = ondisk_xattr_ibody_size(v2->i_xattr_icount);

		vi->raw_blkaddr = le32_to_cpu(v2->i_u.raw_blkaddr);

		inode->i_mode = le16_to_cpu(v2->i_mode);

		i_uid_write(inode, le32_to_cpu(v2->i_uid));

		i_gid_write(inode, le32_to_cpu(v2->i_gid));

		set_nlink(inode, le32_to_cpu(v2->i_nlink));

		/* ns timestamp */

		inode->i_mtime.tv_sec = inode->i_ctime.tv_sec =

			le64_to_cpu(v2->i_ctime);

		inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec =

			le32_to_cpu(v2->i_ctime_nsec);

		inode->i_size = le64_to_cpu(v2->i_size);

	} else if (__inode_version(advise) == EROFS_INODE_LAYOUT_V1) {

		struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);

		vi->inode_isize = sizeof(struct erofs_inode_v1);

		vi->xattr_isize = ondisk_xattr_ibody_size(v1->i_xattr_icount);

		vi->raw_blkaddr = le32_to_cpu(v1->i_u.raw_blkaddr);

		inode->i_mode = le16_to_cpu(v1->i_mode);

		i_uid_write(inode, le16_to_cpu(v1->i_uid));

		i_gid_write(inode, le16_to_cpu(v1->i_gid));

		set_nlink(inode, le16_to_cpu(v1->i_nlink));

		/* use build time to derive all file time */

		inode->i_mtime.tv_sec = inode->i_ctime.tv_sec =

			sbi->build_time;

		inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec =

			sbi->build_time_nsec;

		inode->i_size = le32_to_cpu(v1->i_size);

	} else {

		errln("unsupported on-disk inode version %u of nid %llu",

			__inode_version(advise), vi->nid);

		DBG_BUGON(1);

		return -EIO;

	}

	/* measure inode.i_blocks as the generic filesystem */

	inode->i_blocks = ((inode->i_size - 1) >> 9) + 1;

	return 0;

}

/*

 * try_lock can be required since locking order is:

 *   file data(fs_inode)

 *        meta(bd_inode)

 * but the majority of the callers is "iget",

 * in that case we are pretty sure no deadlock since

 * no data operations exist. However I tend to

 * try_lock since it takes no much overhead and

 * will success immediately.

 */

static int fill_inline_data(struct inode *inode, void *data, unsigned m_pofs)

{

	struct erofs_vnode *vi = EROFS_V(inode);

	int mode = vi->data_mapping_mode;

	DBG_BUGON(mode >= EROFS_INODE_LAYOUT_MAX);

	/* should be inode inline C */

	if (mode != EROFS_INODE_LAYOUT_INLINE)

		return 0;

	/* fast symlink (following ext4) */

	if (S_ISLNK(inode->i_mode) && inode->i_size < PAGE_SIZE) {

		char *lnk = kmalloc(inode->i_size + 1, GFP_KERNEL);

		if (unlikely(lnk == NULL))

			return -ENOMEM;

		m_pofs += vi->inode_isize + vi->xattr_isize;

		BUG_ON(m_pofs + inode->i_size > PAGE_SIZE);

		/* get in-page inline data */

		memcpy(lnk, data + m_pofs, inode->i_size);

		lnk[inode->i_size] = '\0';

		inode->i_link = lnk;

		set_inode_fast_symlink(inode);

	}

	return -EAGAIN;

}

static int fill_inode(struct inode *inode, int isdir)

{

	struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);

	struct erofs_vnode *vi = EROFS_V(inode);

	struct page *page;

	void *data;

	int err;

	erofs_blk_t blkaddr;

	unsigned ofs;

	blkaddr = erofs_blknr(iloc(sbi, vi->nid));

	ofs = erofs_blkoff(iloc(sbi, vi->nid));

	debugln("%s, reading inode nid %llu at %u of blkaddr %u",

		__func__, vi->nid, ofs, blkaddr);

	page = erofs_get_meta_page(inode->i_sb, blkaddr, isdir);

	if (IS_ERR(page)) {

		errln("failed to get inode (nid: %llu) page, err %ld",

			vi->nid, PTR_ERR(page));

		return PTR_ERR(page);

	}

	BUG_ON(!PageUptodate(page));

	data = page_address(page);

	err = read_inode(inode, data + ofs);

	if (!err) {

		/* setup the new inode */

		if (S_ISREG(inode->i_mode)) {

			inode->i_fop = &generic_ro_fops;

		} else if (S_ISDIR(inode->i_mode)) {

			inode->i_op =

				&erofs_dir_iops;

			inode->i_fop = &erofs_dir_fops;

		} else if (S_ISLNK(inode->i_mode)) {

			/* by default, page_get_link is used for symlink */

			inode->i_op =

				&page_symlink_inode_operations;

			inode_nohighmem(inode);

		} else {

			err = -EIO;

			goto out_unlock;

		}

		if (is_inode_layout_compression(inode)) {

			err = -ENOTSUPP;

			goto out_unlock;

		}

		inode->i_mapping->a_ops = &erofs_raw_access_aops;

		/* fill last page if inline data is available */

		fill_inline_data(inode, data, ofs);

	}

out_unlock:

	unlock_page(page);

	put_page(page);

	return err;

}

struct inode *erofs_iget(struct super_block *sb,

	erofs_nid_t nid, bool isdir)

{

	struct inode *inode = iget_locked(sb, nid);

	if (unlikely(inode == NULL))

		return ERR_PTR(-ENOMEM);

	if (inode->i_state & I_NEW) {

		int err;

		struct erofs_vnode *vi = EROFS_V(inode);

		vi->nid = nid;

		err = fill_inode(inode, isdir);

		if (likely(!err))

			unlock_new_inode(inode);

		else {

			iget_failed(inode);

			inode = ERR_PTR(err);

		}

	}

	return inode;

}