[linux.git] / fs / efs / inode.c

// 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_set_atime(inode, be32_to_cpu(efs_inode->di_atime), 0);
	inode_set_mtime(inode, be32_to_cpu(efs_inode->di_mtime), 0);
	inode_set_ctime(inode, be32_to_cpu(efs_inode->di_ctime), 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");
Commit	Line	Data
09c434b8	1	// SPDX-License-Identifier: GPL-2.0-only
1da177e4 LT	2	/*
	3	* inode.c
	4	*
	5	* Copyright (c) 1999 Al Smith
	6	*
	7	* Portions derived from work (c) 1995,1996 Christian Vogelgsang,
	8	* and from work (c) 1998 Mike Shaver.
	9	*/
	10
1da177e4 LT	11	#include <linux/buffer_head.h>
	12	#include <linux/module.h>
	13	#include <linux/fs.h>
45254b4f CH	14	#include "efs.h"
45254b4f CH	15	#include <linux/efs_fs_sb.h>
1da177e4	16
2c69e205	17	static int efs_read_folio(struct file file, struct folio folio)
1da177e4	18	{
2c69e205	19	return block_read_full_folio(folio, efs_get_block);
1da177e4	20	}
2c69e205	21
1da177e4 LT	22	static sector_t _efs_bmap(struct address_space *mapping, sector_t block)
	23	{
	24	return generic_block_bmap(mapping,block,efs_get_block);
	25	}
2c69e205	26
f5e54d6e	27	static const struct address_space_operations efs_aops = {
2c69e205	28	.read_folio = efs_read_folio,
1da177e4 LT	29	.bmap = _efs_bmap
	30	};
	31
	32	static inline void extent_copy(efs_extent src, efs_extent dst) {
	33	/*
	34	* this is slightly evil. it doesn't just copy
	35	* efs_extent from src to dst, it also mangles
	36	* the bits so that dst ends up in cpu byte-order.
	37	*/
	38
	39	dst->cooked.ex_magic = (unsigned int) src->raw[0];
	40	dst->cooked.ex_bn = ((unsigned int) src->raw[1] << 16) \|
	41	((unsigned int) src->raw[2] << 8) \|
	42	((unsigned int) src->raw[3] << 0);
	43	dst->cooked.ex_length = (unsigned int) src->raw[4];
	44	dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) \|
	45	((unsigned int) src->raw[6] << 8) \|
	46	((unsigned int) src->raw[7] << 0);
	47	return;
	48	}
	49
298384cd	50	struct inode efs_iget(struct super_block super, unsigned long ino)
1da177e4 LT	51	{
	52	int i, inode_index;
	53	dev_t device;
	54	u32 rdev;
	55	struct buffer_head *bh;
298384cd DH	56	struct efs_sb_info *sb = SUPER_INFO(super);
298384cd DH	57	struct efs_inode_info *in;
1da177e4 LT	58	efs_block_t block, offset;
1da177e4 LT	59	struct efs_dinode *efs_inode;
298384cd DH	60	struct inode *inode;
	61
	62	inode = iget_locked(super, ino);
136eefa4	63	if (!inode)
298384cd DH	64	return ERR_PTR(-ENOMEM);
	65	if (!(inode->i_state & I_NEW))
	66	return inode;
	67
	68	in = INODE_INFO(inode);
	69
1da177e4 LT	70	/*
	71	** EFS layout:
	72	**
	73	** \| cylinder group \| cylinder group \| cylinder group ..etc
	74	** \|inodes\|data \|inodes\|data \|inodes\|data ..etc
	75	**
	76	** work out the inode block index, (considering initially that the
	77	** inodes are stored as consecutive blocks). then work out the block
	78	** number of that inode given the above layout, and finally the
	79	** offset of the inode within that block.
	80	*/
	81
	82	inode_index = inode->i_ino /
	83	(EFS_BLOCKSIZE / sizeof(struct efs_dinode));
	84
	85	block = sb->fs_start + sb->first_block +
	86	(sb->group_size * (inode_index / sb->inode_blocks)) +
	87	(inode_index % sb->inode_blocks);
	88
	89	offset = (inode->i_ino %
	90	(EFS_BLOCKSIZE / sizeof(struct efs_dinode))) *
	91	sizeof(struct efs_dinode);
	92
	93	bh = sb_bread(inode->i_sb, block);
	94	if (!bh) {
f403d1db	95	pr_warn("%s() failed at block %d\n", __func__, block);
1da177e4 LT	96	goto read_inode_error;
	97	}
	98
	99	efs_inode = (struct efs_dinode *) (bh->b_data + offset);
	100
	101	inode->i_mode = be16_to_cpu(efs_inode->di_mode);
bfe86848	102	set_nlink(inode, be16_to_cpu(efs_inode->di_nlink));
5d4ea4da EB	103	i_uid_write(inode, (uid_t)be16_to_cpu(efs_inode->di_uid));
5d4ea4da EB	104	i_gid_write(inode, (gid_t)be16_to_cpu(efs_inode->di_gid));
1da177e4	105	inode->i_size = be32_to_cpu(efs_inode->di_size);
89ddde88 JL	106	inode_set_atime(inode, be32_to_cpu(efs_inode->di_atime), 0);
89ddde88 JL	107	inode_set_mtime(inode, be32_to_cpu(efs_inode->di_mtime), 0);
a68d1f51	108	inode_set_ctime(inode, be32_to_cpu(efs_inode->di_ctime), 0);
1da177e4 LT	109
	110	/* this is the number of blocks in the file */
	111	if (inode->i_size == 0) {
	112	inode->i_blocks = 0;
	113	} else {
	114	inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;
	115	}
	116
	117	rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev);
	118	if (rdev == 0xffff) {
	119	rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev);
	120	if (sysv_major(rdev) > 0xfff)
	121	device = 0;
	122	else
	123	device = MKDEV(sysv_major(rdev), sysv_minor(rdev));
	124	} else
	125	device = old_decode_dev(rdev);
	126
	127	/* get the number of extents for this object */
	128	in->numextents = be16_to_cpu(efs_inode->di_numextents);
	129	in->lastextent = 0;
	130
	131	/* copy the extents contained within the inode to memory */
	132	for(i = 0; i < EFS_DIRECTEXTENTS; i++) {
	133	extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i]));
	134	if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) {
f403d1db FF	135	pr_warn("extent %d has bad magic number in inode %lu\n",
f403d1db FF	136	i, inode->i_ino);
1da177e4 LT	137	brelse(bh);
	138	goto read_inode_error;
	139	}
	140	}
	141
	142	brelse(bh);
d1826f2a FF	143	pr_debug("efs_iget(): inode %lu, extents %d, mode %o\n",
d1826f2a FF	144	inode->i_ino, in->numextents, inode->i_mode);
1da177e4 LT	145	switch (inode->i_mode & S_IFMT) {
	146	case S_IFDIR:
	147	inode->i_op = &efs_dir_inode_operations;
	148	inode->i_fop = &efs_dir_operations;
	149	break;
	150	case S_IFREG:
	151	inode->i_fop = &generic_ro_fops;
	152	inode->i_data.a_ops = &efs_aops;
	153	break;
	154	case S_IFLNK:
	155	inode->i_op = &page_symlink_inode_operations;
21fc61c7	156	inode_nohighmem(inode);
1da177e4 LT	157	inode->i_data.a_ops = &efs_symlink_aops;
	158	break;
	159	case S_IFCHR:
	160	case S_IFBLK:
	161	case S_IFIFO:
	162	init_special_inode(inode, inode->i_mode, device);
	163	break;
	164	default:
f403d1db	165	pr_warn("unsupported inode mode %o\n", inode->i_mode);
1da177e4 LT	166	goto read_inode_error;
	167	break;
	168	}
	169
298384cd DH	170	unlock_new_inode(inode);
298384cd DH	171	return inode;
1da177e4 LT	172
1da177e4 LT	173	read_inode_error:
f403d1db	174	pr_warn("failed to read inode %lu\n", inode->i_ino);
298384cd DH	175	iget_failed(inode);
298384cd DH	176	return ERR_PTR(-EIO);
1da177e4 LT	177	}
	178
	179	static inline efs_block_t
	180	efs_extent_check(efs_extent ptr, efs_block_t block, struct efs_sb_info sb) {
	181	efs_block_t start;
	182	efs_block_t length;
	183	efs_block_t offset;
	184
	185	/*
	186	* given an extent and a logical block within a file,
	187	* can this block be found within this extent ?
	188	*/
	189	start = ptr->cooked.ex_bn;
	190	length = ptr->cooked.ex_length;
	191	offset = ptr->cooked.ex_offset;
	192
	193	if ((block >= offset) && (block < offset+length)) {
	194	return(sb->fs_start + start + block - offset);
	195	} else {
	196	return 0;
	197	}
	198	}
	199
	200	efs_block_t efs_map_block(struct inode *inode, efs_block_t block) {
	201	struct efs_sb_info *sb = SUPER_INFO(inode->i_sb);
	202	struct efs_inode_info *in = INODE_INFO(inode);
	203	struct buffer_head *bh = NULL;
	204
	205	int cur, last, first = 1;
	206	int ibase, ioffset, dirext, direxts, indext, indexts;
	207	efs_block_t iblock, result = 0, lastblock = 0;
	208	efs_extent ext, *exts;
	209
	210	last = in->lastextent;
	211
	212	if (in->numextents <= EFS_DIRECTEXTENTS) {
	213	/* first check the last extent we returned */
	214	if ((result = efs_extent_check(&in->extents[last], block, sb)))
	215	return result;
	216
	217	/* if we only have one extent then nothing can be found */
	218	if (in->numextents == 1) {
f403d1db	219	pr_err("%s() failed to map (1 extent)\n", __func__);
1da177e4 LT	220	return 0;
	221	}
	222
	223	direxts = in->numextents;
	224
	225	/*
	226	* check the stored extents in the inode
	227	* start with next extent and check forwards
	228	*/
	229	for(dirext = 1; dirext < direxts; dirext++) {
	230	cur = (last + dirext) % in->numextents;
	231	if ((result = efs_extent_check(&in->extents[cur], block, sb))) {
	232	in->lastextent = cur;
	233	return result;
	234	}
	235	}
	236
f403d1db	237	pr_err("%s() failed to map block %u (dir)\n", __func__, block);
1da177e4 LT	238	return 0;
	239	}
	240
d1826f2a FF	241	pr_debug("%s(): indirect search for logical block %u\n",
d1826f2a FF	242	__func__, block);
1da177e4 LT	243	direxts = in->extents[0].cooked.ex_offset;
	244	indexts = in->numextents;
	245
	246	for(indext = 0; indext < indexts; indext++) {
	247	cur = (last + indext) % indexts;
	248
	249	/*
	250	* work out which direct extent contains `cur'.
	251	*
	252	* also compute ibase: i.e. the number of the first
	253	* indirect extent contained within direct extent `cur'.
	254	*
	255	*/
	256	ibase = 0;
	257	for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {
	258	ibase += in->extents[dirext].cooked.ex_length *
	259	(EFS_BLOCKSIZE / sizeof(efs_extent));
	260	}
	261
	262	if (dirext == direxts) {
	263	/* should never happen */
f403d1db FF	264	pr_err("couldn't find direct extent for indirect extent %d (block %u)\n",
f403d1db FF	265	cur, block);
1da177e4 LT	266	if (bh) brelse(bh);
	267	return 0;
	268	}
	269
	270	/* work out block number and offset of this indirect extent */
	271	iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +
	272	(cur - ibase) /
	273	(EFS_BLOCKSIZE / sizeof(efs_extent));
	274	ioffset = (cur - ibase) %
	275	(EFS_BLOCKSIZE / sizeof(efs_extent));
	276
	277	if (first \|\| lastblock != iblock) {
	278	if (bh) brelse(bh);
	279
	280	bh = sb_bread(inode->i_sb, iblock);
	281	if (!bh) {
f403d1db FF	282	pr_err("%s() failed at block %d\n",
f403d1db FF	283	__func__, iblock);
1da177e4 LT	284	return 0;
1da177e4 LT	285	}
d1826f2a FF	286	pr_debug("%s(): read indirect extent block %d\n",
d1826f2a FF	287	__func__, iblock);
1da177e4 LT	288	first = 0;
	289	lastblock = iblock;
	290	}
	291
	292	exts = (efs_extent *) bh->b_data;
	293
	294	extent_copy(&(exts[ioffset]), &ext);
	295
	296	if (ext.cooked.ex_magic != 0) {
f403d1db FF	297	pr_err("extent %d has bad magic number in block %d\n",
f403d1db FF	298	cur, iblock);
1da177e4 LT	299	if (bh) brelse(bh);
	300	return 0;
	301	}
	302
	303	if ((result = efs_extent_check(&ext, block, sb))) {
	304	if (bh) brelse(bh);
	305	in->lastextent = cur;
	306	return result;
	307	}
	308	}
	309	if (bh) brelse(bh);
f403d1db	310	pr_err("%s() failed to map block %u (indir)\n", __func__, block);
1da177e4 LT	311	return 0;
	312	}
	313
	314	MODULE_LICENSE("GPL");