fs/efs/inode.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * inode.c
  *
  * Copyright (c) 1999 Al Smith
  *
  * Portions derived from work (c) 1995,1996 Christian Vogelgsang,
  *              and from work (c) 1998 Mike Shaver.
  */

 #include <linux/buffer_head.h>
 #include <linux/module.h>
 #include <linux/fs.h>
 #include "efs.h"
 #include <linux/efs_fs_sb.h>

 static int efs_read_folio(struct file *file, struct folio *folio)
 {
 	return block_read_full_folio(folio, efs_get_block);
 }

 static sector_t _efs_bmap(struct address_space *mapping, sector_t block)
 {
 	return generic_block_bmap(mapping,block,efs_get_block);
 }

 static const struct address_space_operations efs_aops = {
 	.read_folio = efs_read_folio,
 	.bmap = _efs_bmap
 };

 static inline void extent_copy(efs_extent *src, efs_extent *dst) {
 	/*
 	 * this is slightly evil. it doesn't just copy
 	 * efs_extent from src to dst, it also mangles
 	 * the bits so that dst ends up in cpu byte-order.
 	 */

 	dst->cooked.ex_magic  =  (unsigned int) src->raw[0];
 	dst->cooked.ex_bn     = ((unsigned int) src->raw[1] << 16) |
 				((unsigned int) src->raw[2] <<  8) |
 				((unsigned int) src->raw[3] <<  0);
 	dst->cooked.ex_length =  (unsigned int) src->raw[4];
 	dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) |
 				((unsigned int) src->raw[6] <<  8) |
 				((unsigned int) src->raw[7] <<  0);
 	return;
 }

 struct inode *efs_iget(struct super_block *super, unsigned long ino)
 {
 	int i, inode_index;
 	dev_t device;
 	u32 rdev;
 	struct buffer_head *bh;
 	struct efs_sb_info    *sb = SUPER_INFO(super);
 	struct efs_inode_info *in;
 	efs_block_t block, offset;
 	struct efs_dinode *efs_inode;
 	struct inode *inode;

 	inode = iget_locked(super, ino);
 	if (!inode)
 		return ERR_PTR(-ENOMEM);
 	if (!(inode->i_state & I_NEW))
 		return inode;

 	in = INODE_INFO(inode);

 	/*
 	** EFS layout:
 	**
 	** |   cylinder group    |   cylinder group    |   cylinder group ..etc
 	** |inodes|data          |inodes|data          |inodes|data       ..etc
 	**
 	** work out the inode block index, (considering initially that the
 	** inodes are stored as consecutive blocks). then work out the block
 	** number of that inode given the above layout, and finally the
 	** offset of the inode within that block.
 	*/

 	inode_index = inode->i_ino /
 		(EFS_BLOCKSIZE / sizeof(struct efs_dinode));

 	block = sb->fs_start + sb->first_block +
 		(sb->group_size * (inode_index / sb->inode_blocks)) +
 		(inode_index % sb->inode_blocks);

 	offset = (inode->i_ino %
 			(EFS_BLOCKSIZE / sizeof(struct efs_dinode))) *
 		sizeof(struct efs_dinode);

 	bh = sb_bread(inode->i_sb, block);
 	if (!bh) {
 		pr_warn("%s() failed at block %d\n", __func__, block);
 		goto read_inode_error;
 	}

 	efs_inode = (struct efs_dinode *) (bh->b_data + offset);

 	inode->i_mode  = be16_to_cpu(efs_inode->di_mode);
 	set_nlink(inode, be16_to_cpu(efs_inode->di_nlink));
 	i_uid_write(inode, (uid_t)be16_to_cpu(efs_inode->di_uid));
 	i_gid_write(inode, (gid_t)be16_to_cpu(efs_inode->di_gid));
 	inode->i_size  = be32_to_cpu(efs_inode->di_size);
 	inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime);
 	inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime);
 	inode->i_ctime.tv_sec = be32_to_cpu(efs_inode->di_ctime);
 	inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;

 	/* this is the number of blocks in the file */
 	if (inode->i_size == 0) {
 		inode->i_blocks = 0;
 	} else {
 		inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;
 	}

 	rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev);
 	if (rdev == 0xffff) {
 		rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev);
 		if (sysv_major(rdev) > 0xfff)
 			device = 0;
 		else
 			device = MKDEV(sysv_major(rdev), sysv_minor(rdev));
 	} else
 		device = old_decode_dev(rdev);

 	/* get the number of extents for this object */
 	in->numextents = be16_to_cpu(efs_inode->di_numextents);
 	in->lastextent = 0;

 	/* copy the extents contained within the inode to memory */
 	for(i = 0; i < EFS_DIRECTEXTENTS; i++) {
 		extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i]));
 		if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) {
 			pr_warn("extent %d has bad magic number in inode %lu\n",
 				i, inode->i_ino);
 			brelse(bh);
 			goto read_inode_error;
 		}
 	}

 	brelse(bh);
 	pr_debug("efs_iget(): inode %lu, extents %d, mode %o\n",
 		 inode->i_ino, in->numextents, inode->i_mode);
 	switch (inode->i_mode & S_IFMT) {
 		case S_IFDIR:
 			inode->i_op = &efs_dir_inode_operations;
 			inode->i_fop = &efs_dir_operations;
 			break;
 		case S_IFREG:
 			inode->i_fop = &generic_ro_fops;
 			inode->i_data.a_ops = &efs_aops;
 			break;
 		case S_IFLNK:
 			inode->i_op = &page_symlink_inode_operations;
 			inode_nohighmem(inode);
 			inode->i_data.a_ops = &efs_symlink_aops;
 			break;
 		case S_IFCHR:
 		case S_IFBLK:
 		case S_IFIFO:
 			init_special_inode(inode, inode->i_mode, device);
 			break;
 		default:
 			pr_warn("unsupported inode mode %o\n", inode->i_mode);
 			goto read_inode_error;
 			break;
 	}

 	unlock_new_inode(inode);
 	return inode;

 read_inode_error:
 	pr_warn("failed to read inode %lu\n", inode->i_ino);
 	iget_failed(inode);
 	return ERR_PTR(-EIO);
 }

 static inline efs_block_t
 efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) {
 	efs_block_t start;
 	efs_block_t length;
 	efs_block_t offset;

 	/*
 	 * given an extent and a logical block within a file,
 	 * can this block be found within this extent ?
 	 */
 	start  = ptr->cooked.ex_bn;
 	length = ptr->cooked.ex_length;
 	offset = ptr->cooked.ex_offset;

 	if ((block >= offset) && (block < offset+length)) {
 		return(sb->fs_start + start + block - offset);
 	} else {
 		return 0;
 	}
 }

 efs_block_t efs_map_block(struct inode *inode, efs_block_t block) {
 	struct efs_sb_info    *sb = SUPER_INFO(inode->i_sb);
 	struct efs_inode_info *in = INODE_INFO(inode);
 	struct buffer_head    *bh = NULL;

 	int cur, last, first = 1;
 	int ibase, ioffset, dirext, direxts, indext, indexts;
 	efs_block_t iblock, result = 0, lastblock = 0;
 	efs_extent ext, *exts;

 	last = in->lastextent;

 	if (in->numextents <= EFS_DIRECTEXTENTS) {
 		/* first check the last extent we returned */
 		if ((result = efs_extent_check(&in->extents[last], block, sb)))
 			return result;

 		/* if we only have one extent then nothing can be found */
 		if (in->numextents == 1) {
 			pr_err("%s() failed to map (1 extent)\n", __func__);
 			return 0;
 		}

 		direxts = in->numextents;

 		/*
 		 * check the stored extents in the inode
 		 * start with next extent and check forwards
 		 */
 		for(dirext = 1; dirext < direxts; dirext++) {
 			cur = (last + dirext) % in->numextents;
 			if ((result = efs_extent_check(&in->extents[cur], block, sb))) {
 				in->lastextent = cur;
 				return result;
 			}
 		}

 		pr_err("%s() failed to map block %u (dir)\n", __func__, block);
 		return 0;
 	}

 	pr_debug("%s(): indirect search for logical block %u\n",
 		 __func__, block);
 	direxts = in->extents[0].cooked.ex_offset;
 	indexts = in->numextents;

 	for(indext = 0; indext < indexts; indext++) {
 		cur = (last + indext) % indexts;

 		/*
 		 * work out which direct extent contains `cur'.
 		 *
 		 * also compute ibase: i.e. the number of the first
 		 * indirect extent contained within direct extent `cur'.
 		 *
 		 */
 		ibase = 0;
 		for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {
 			ibase += in->extents[dirext].cooked.ex_length *
 				(EFS_BLOCKSIZE / sizeof(efs_extent));
 		}

 		if (dirext == direxts) {
 			/* should never happen */
 			pr_err("couldn't find direct extent for indirect extent %d (block %u)\n",
 			       cur, block);
 			if (bh) brelse(bh);
 			return 0;
 		}

 		/* work out block number and offset of this indirect extent */
 		iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +
 			(cur - ibase) /
 			(EFS_BLOCKSIZE / sizeof(efs_extent));
 		ioffset = (cur - ibase) %
 			(EFS_BLOCKSIZE / sizeof(efs_extent));

 		if (first || lastblock != iblock) {
 			if (bh) brelse(bh);

 			bh = sb_bread(inode->i_sb, iblock);
 			if (!bh) {
 				pr_err("%s() failed at block %d\n",
 				       __func__, iblock);
 				return 0;
 			}
 			pr_debug("%s(): read indirect extent block %d\n",
 				 __func__, iblock);
 			first = 0;
 			lastblock = iblock;
 		}

 		exts = (efs_extent *) bh->b_data;

 		extent_copy(&(exts[ioffset]), &ext);

 		if (ext.cooked.ex_magic != 0) {
 			pr_err("extent %d has bad magic number in block %d\n",
 			       cur, iblock);
 			if (bh) brelse(bh);
 			return 0;
 		}

 		if ((result = efs_extent_check(&ext, block, sb))) {
 			if (bh) brelse(bh);
 			in->lastextent = cur;
 			return result;
 		}
 	}
 	if (bh) brelse(bh);
 	pr_err("%s() failed to map block %u (indir)\n", __func__, block);
 	return 0;
 }

 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* inode.c
	*
	* Copyright (c) 1999 Al Smith
	*
	* Portions derived from work (c) 1995,1996 Christian Vogelgsang,
	* and from work (c) 1998 Mike Shaver.
	*/

	#include <linux/buffer_head.h>
	#include <linux/module.h>
	#include <linux/fs.h>
	#include "efs.h"
	#include <linux/efs_fs_sb.h>

	static int efs_read_folio(struct file file, struct folio folio)
	{
	return block_read_full_folio(folio, efs_get_block);
	}

	static sector_t _efs_bmap(struct address_space *mapping, sector_t block)
	{
	return generic_block_bmap(mapping,block,efs_get_block);
	}

	static const struct address_space_operations efs_aops = {
	.read_folio = efs_read_folio,
	.bmap = _efs_bmap
	};

	static inline void extent_copy(efs_extent src, efs_extent dst) {
	/*
	* this is slightly evil. it doesn't just copy
	* efs_extent from src to dst, it also mangles
	* the bits so that dst ends up in cpu byte-order.
	*/

	dst->cooked.ex_magic = (unsigned int) src->raw[0];
	dst->cooked.ex_bn = ((unsigned int) src->raw[1] << 16) \|
	((unsigned int) src->raw[2] << 8) \|
	((unsigned int) src->raw[3] << 0);
	dst->cooked.ex_length = (unsigned int) src->raw[4];
	dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) \|
	((unsigned int) src->raw[6] << 8) \|
	((unsigned int) src->raw[7] << 0);
	return;
	}

	struct inode efs_iget(struct super_block super, unsigned long ino)
	{
	int i, inode_index;
	dev_t device;
	u32 rdev;
	struct buffer_head *bh;
	struct efs_sb_info *sb = SUPER_INFO(super);
	struct efs_inode_info *in;
	efs_block_t block, offset;
	struct efs_dinode *efs_inode;
	struct inode *inode;

	inode = iget_locked(super, ino);
	if (!inode)
	return ERR_PTR(-ENOMEM);
	if (!(inode->i_state & I_NEW))
	return inode;

	in = INODE_INFO(inode);

	/*
	** EFS layout:
	**
	** \| cylinder group \| cylinder group \| cylinder group ..etc
	** \|inodes\|data \|inodes\|data \|inodes\|data ..etc
	**
	** work out the inode block index, (considering initially that the
	** inodes are stored as consecutive blocks). then work out the block
	** number of that inode given the above layout, and finally the
	** offset of the inode within that block.
	*/

	inode_index = inode->i_ino /
	(EFS_BLOCKSIZE / sizeof(struct efs_dinode));

	block = sb->fs_start + sb->first_block +
	(sb->group_size * (inode_index / sb->inode_blocks)) +
	(inode_index % sb->inode_blocks);

	offset = (inode->i_ino %
	(EFS_BLOCKSIZE / sizeof(struct efs_dinode))) *
	sizeof(struct efs_dinode);

	bh = sb_bread(inode->i_sb, block);
	if (!bh) {
	pr_warn("%s() failed at block %d\n", __func__, block);
	goto read_inode_error;
	}

	efs_inode = (struct efs_dinode *) (bh->b_data + offset);

	inode->i_mode = be16_to_cpu(efs_inode->di_mode);
	set_nlink(inode, be16_to_cpu(efs_inode->di_nlink));
	i_uid_write(inode, (uid_t)be16_to_cpu(efs_inode->di_uid));
	i_gid_write(inode, (gid_t)be16_to_cpu(efs_inode->di_gid));
	inode->i_size = be32_to_cpu(efs_inode->di_size);
	inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime);
	inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime);
	inode->i_ctime.tv_sec = be32_to_cpu(efs_inode->di_ctime);
	inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;

	/* this is the number of blocks in the file */
	if (inode->i_size == 0) {
	inode->i_blocks = 0;
	} else {
	inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;
	}

	rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev);
	if (rdev == 0xffff) {
	rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev);
	if (sysv_major(rdev) > 0xfff)
	device = 0;
	else
	device = MKDEV(sysv_major(rdev), sysv_minor(rdev));
	} else
	device = old_decode_dev(rdev);

	/* get the number of extents for this object */
	in->numextents = be16_to_cpu(efs_inode->di_numextents);
	in->lastextent = 0;

	/* copy the extents contained within the inode to memory */
	for(i = 0; i < EFS_DIRECTEXTENTS; i++) {
	extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i]));
	if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) {
	pr_warn("extent %d has bad magic number in inode %lu\n",
	i, inode->i_ino);
	brelse(bh);
	goto read_inode_error;
	}
	}

	brelse(bh);
	pr_debug("efs_iget(): inode %lu, extents %d, mode %o\n",
	inode->i_ino, in->numextents, inode->i_mode);
	switch (inode->i_mode & S_IFMT) {
	case S_IFDIR:
	inode->i_op = &efs_dir_inode_operations;
	inode->i_fop = &efs_dir_operations;
	break;
	case S_IFREG:
	inode->i_fop = &generic_ro_fops;
	inode->i_data.a_ops = &efs_aops;
	break;
	case S_IFLNK:
	inode->i_op = &page_symlink_inode_operations;
	inode_nohighmem(inode);
	inode->i_data.a_ops = &efs_symlink_aops;
	break;
	case S_IFCHR:
	case S_IFBLK:
	case S_IFIFO:
	init_special_inode(inode, inode->i_mode, device);
	break;
	default:
	pr_warn("unsupported inode mode %o\n", inode->i_mode);
	goto read_inode_error;
	break;
	}

	unlock_new_inode(inode);
	return inode;

	read_inode_error:
	pr_warn("failed to read inode %lu\n", inode->i_ino);
	iget_failed(inode);
	return ERR_PTR(-EIO);
	}

	static inline efs_block_t
	efs_extent_check(efs_extent ptr, efs_block_t block, struct efs_sb_info sb) {
	efs_block_t start;
	efs_block_t length;
	efs_block_t offset;

	/*
	* given an extent and a logical block within a file,
	* can this block be found within this extent ?
	*/
	start = ptr->cooked.ex_bn;
	length = ptr->cooked.ex_length;
	offset = ptr->cooked.ex_offset;

	if ((block >= offset) && (block < offset+length)) {
	return(sb->fs_start + start + block - offset);
	} else {
	return 0;
	}
	}

	efs_block_t efs_map_block(struct inode *inode, efs_block_t block) {
	struct efs_sb_info *sb = SUPER_INFO(inode->i_sb);
	struct efs_inode_info *in = INODE_INFO(inode);
	struct buffer_head *bh = NULL;

	int cur, last, first = 1;
	int ibase, ioffset, dirext, direxts, indext, indexts;
	efs_block_t iblock, result = 0, lastblock = 0;
	efs_extent ext, *exts;

	last = in->lastextent;

	if (in->numextents <= EFS_DIRECTEXTENTS) {
	/* first check the last extent we returned */
	if ((result = efs_extent_check(&in->extents[last], block, sb)))
	return result;

	/* if we only have one extent then nothing can be found */
	if (in->numextents == 1) {
	pr_err("%s() failed to map (1 extent)\n", __func__);
	return 0;
	}

	direxts = in->numextents;

	/*
	* check the stored extents in the inode
	* start with next extent and check forwards
	*/
	for(dirext = 1; dirext < direxts; dirext++) {
	cur = (last + dirext) % in->numextents;
	if ((result = efs_extent_check(&in->extents[cur], block, sb))) {
	in->lastextent = cur;
	return result;
	}
	}

	pr_err("%s() failed to map block %u (dir)\n", __func__, block);
	return 0;
	}

	pr_debug("%s(): indirect search for logical block %u\n",
	__func__, block);
	direxts = in->extents[0].cooked.ex_offset;
	indexts = in->numextents;

	for(indext = 0; indext < indexts; indext++) {
	cur = (last + indext) % indexts;

	/*
	* work out which direct extent contains `cur'.
	*
	* also compute ibase: i.e. the number of the first
	* indirect extent contained within direct extent `cur'.
	*
	*/
	ibase = 0;
	for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {
	ibase += in->extents[dirext].cooked.ex_length *
	(EFS_BLOCKSIZE / sizeof(efs_extent));
	}

	if (dirext == direxts) {
	/* should never happen */
	pr_err("couldn't find direct extent for indirect extent %d (block %u)\n",
	cur, block);
	if (bh) brelse(bh);
	return 0;
	}

	/* work out block number and offset of this indirect extent */
	iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +
	(cur - ibase) /
	(EFS_BLOCKSIZE / sizeof(efs_extent));
	ioffset = (cur - ibase) %
	(EFS_BLOCKSIZE / sizeof(efs_extent));

	if (first \|\| lastblock != iblock) {
	if (bh) brelse(bh);

	bh = sb_bread(inode->i_sb, iblock);
	if (!bh) {
	pr_err("%s() failed at block %d\n",
	__func__, iblock);
	return 0;
	}
	pr_debug("%s(): read indirect extent block %d\n",
	__func__, iblock);
	first = 0;
	lastblock = iblock;
	}

	exts = (efs_extent *) bh->b_data;

	extent_copy(&(exts[ioffset]), &ext);

	if (ext.cooked.ex_magic != 0) {
	pr_err("extent %d has bad magic number in block %d\n",
	cur, iblock);
	if (bh) brelse(bh);
	return 0;
	}

	if ((result = efs_extent_check(&ext, block, sb))) {
	if (bh) brelse(bh);
	in->lastextent = cur;
	return result;
	}
	}
	if (bh) brelse(bh);
	pr_err("%s() failed to map block %u (indir)\n", __func__, block);
	return 0;
	}

	MODULE_LICENSE("GPL");