fs/hpfs/map.c - arm/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  *  linux/fs/hpfs/map.c
  *
  *  Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999
  *
  *  mapping structures to memory with some minimal checks
  */

 #include "hpfs_fn.h"

 __le32 *hpfs_map_dnode_bitmap(struct super_block *s, struct quad_buffer_head *qbh)
 {
 	return hpfs_map_4sectors(s, hpfs_sb(s)->sb_dmap, qbh, 0);
 }

 __le32 *hpfs_map_bitmap(struct super_block *s, unsigned bmp_block,
 			 struct quad_buffer_head *qbh, char *id)
 {
 	secno sec;
 	__le32 *ret;
 	unsigned n_bands = (hpfs_sb(s)->sb_fs_size + 0x3fff) >> 14;
 	if (hpfs_sb(s)->sb_chk) if (bmp_block >= n_bands) {
 		hpfs_error(s, "hpfs_map_bitmap called with bad parameter: %08x at %s", bmp_block, id);
 		return NULL;
 	}
 	sec = le32_to_cpu(hpfs_sb(s)->sb_bmp_dir[bmp_block]);
 	if (!sec || sec > hpfs_sb(s)->sb_fs_size-4) {
 		hpfs_error(s, "invalid bitmap block pointer %08x -> %08x at %s", bmp_block, sec, id);
 		return NULL;
 	}
 	ret = hpfs_map_4sectors(s, sec, qbh, 4);
 	if (ret) hpfs_prefetch_bitmap(s, bmp_block + 1);
 	return ret;
 }

 void hpfs_prefetch_bitmap(struct super_block *s, unsigned bmp_block)
 {
 	unsigned to_prefetch, next_prefetch;
 	unsigned n_bands = (hpfs_sb(s)->sb_fs_size + 0x3fff) >> 14;
 	if (unlikely(bmp_block >= n_bands))
 		return;
 	to_prefetch = le32_to_cpu(hpfs_sb(s)->sb_bmp_dir[bmp_block]);
 	if (unlikely(bmp_block + 1 >= n_bands))
 		next_prefetch = 0;
 	else
 		next_prefetch = le32_to_cpu(hpfs_sb(s)->sb_bmp_dir[bmp_block + 1]);
 	hpfs_prefetch_sectors(s, to_prefetch, 4 + 4 * (to_prefetch + 4 == next_prefetch));
 }

 /*
  * Load first code page into kernel memory, return pointer to 256-byte array,
  * first 128 bytes are uppercasing table for chars 128-255, next 128 bytes are
  * lowercasing table
  */

 unsigned char *hpfs_load_code_page(struct super_block *s, secno cps)
 {
 	struct buffer_head *bh;
 	secno cpds;
 	unsigned cpi;
 	unsigned char *ptr;
 	unsigned char *cp_table;
 	int i;
 	struct code_page_data *cpd;
 	struct code_page_directory *cp = hpfs_map_sector(s, cps, &bh, 0);
 	if (!cp) return NULL;
 	if (le32_to_cpu(cp->magic) != CP_DIR_MAGIC) {
 		pr_err("Code page directory magic doesn't match (magic = %08x)\n",
 			le32_to_cpu(cp->magic));
 		brelse(bh);
 		return NULL;
 	}
 	if (!le32_to_cpu(cp->n_code_pages)) {
 		pr_err("n_code_pages == 0\n");
 		brelse(bh);
 		return NULL;
 	}
 	cpds = le32_to_cpu(cp->array[0].code_page_data);
 	cpi = le16_to_cpu(cp->array[0].index);
 	brelse(bh);

 	if (cpi >= 3) {
 		pr_err("Code page index out of array\n");
 		return NULL;
 	}

 	if (!(cpd = hpfs_map_sector(s, cpds, &bh, 0))) return NULL;
 	if (le16_to_cpu(cpd->offs[cpi]) > 0x178) {
 		pr_err("Code page index out of sector\n");
 		brelse(bh);
 		return NULL;
 	}
 	ptr = (unsigned char *)cpd + le16_to_cpu(cpd->offs[cpi]) + 6;
 	if (!(cp_table = kmalloc(256, GFP_KERNEL))) {
 		pr_err("out of memory for code page table\n");
 		brelse(bh);
 		return NULL;
 	}
 	memcpy(cp_table, ptr, 128);
 	brelse(bh);

 	/* Try to build lowercasing table from uppercasing one */

 	for (i=128; i<256; i++) cp_table[i]=i;
 	for (i=128; i<256; i++) if (cp_table[i-128]!=i && cp_table[i-128]>=128)
 		cp_table[cp_table[i-128]] = i;

 	return cp_table;
 }

 __le32 *hpfs_load_bitmap_directory(struct super_block *s, secno bmp)
 {
 	struct buffer_head *bh;
 	int n = (hpfs_sb(s)->sb_fs_size + 0x200000 - 1) >> 21;
 	int i;
 	__le32 *b;
 	if (!(b = kmalloc(n * 512, GFP_KERNEL))) {
 		pr_err("can't allocate memory for bitmap directory\n");
 		return NULL;
 	}
 	for (i=0;i<n;i++) {
 		__le32 *d = hpfs_map_sector(s, bmp+i, &bh, n - i - 1);
 		if (!d) {
 			kfree(b);
 			return NULL;
 		}
 		memcpy((char *)b + 512 * i, d, 512);
 		brelse(bh);
 	}
 	return b;
 }

 void hpfs_load_hotfix_map(struct super_block *s, struct hpfs_spare_block *spareblock)
 {
 	struct quad_buffer_head qbh;
 	__le32 *directory;
 	u32 n_hotfixes, n_used_hotfixes;
 	unsigned i;

 	n_hotfixes = le32_to_cpu(spareblock->n_spares);
 	n_used_hotfixes = le32_to_cpu(spareblock->n_spares_used);

 	if (n_hotfixes > 256 || n_used_hotfixes > n_hotfixes) {
 		hpfs_error(s, "invalid number of hotfixes: %u, used: %u", n_hotfixes, n_used_hotfixes);
 		return;
 	}
 	if (!(directory = hpfs_map_4sectors(s, le32_to_cpu(spareblock->hotfix_map), &qbh, 0))) {
 		hpfs_error(s, "can't load hotfix map");
 		return;
 	}
 	for (i = 0; i < n_used_hotfixes; i++) {
 		hpfs_sb(s)->hotfix_from[i] = le32_to_cpu(directory[i]);
 		hpfs_sb(s)->hotfix_to[i] = le32_to_cpu(directory[n_hotfixes + i]);
 	}
 	hpfs_sb(s)->n_hotfixes = n_used_hotfixes;
 	hpfs_brelse4(&qbh);
 }

 /*
  * Load fnode to memory
  */

 struct fnode *hpfs_map_fnode(struct super_block *s, ino_t ino, struct buffer_head **bhp)
 {
 	struct fnode *fnode;
 	if (hpfs_sb(s)->sb_chk) if (hpfs_chk_sectors(s, ino, 1, "fnode")) {
 		return NULL;
 	}
 	if ((fnode = hpfs_map_sector(s, ino, bhp, FNODE_RD_AHEAD))) {
 		if (hpfs_sb(s)->sb_chk) {
 			struct extended_attribute *ea;
 			struct extended_attribute *ea_end;
 			if (le32_to_cpu(fnode->magic) != FNODE_MAGIC) {
 				hpfs_error(s, "bad magic on fnode %08lx",
 					(unsigned long)ino);
 				goto bail;
 			}
 			if (!fnode_is_dir(fnode)) {
 				if ((unsigned)fnode->btree.n_used_nodes + (unsigned)fnode->btree.n_free_nodes !=
 				    (bp_internal(&fnode->btree) ? 12 : 8)) {
 					hpfs_error(s,
 					   "bad number of nodes in fnode %08lx",
 					    (unsigned long)ino);
 					goto bail;
 				}
 				if (le16_to_cpu(fnode->btree.first_free) !=
 				    8 + fnode->btree.n_used_nodes * (bp_internal(&fnode->btree) ? 8 : 12)) {
 					hpfs_error(s,
 					    "bad first_free pointer in fnode %08lx",
 					    (unsigned long)ino);
 					goto bail;
 				}
 			}
 			if (le16_to_cpu(fnode->ea_size_s) && (le16_to_cpu(fnode->ea_offs) < 0xc4 ||
 			   le16_to_cpu(fnode->ea_offs) + le16_to_cpu(fnode->acl_size_s) + le16_to_cpu(fnode->ea_size_s) > 0x200)) {
 				hpfs_error(s,
 					"bad EA info in fnode %08lx: ea_offs == %04x ea_size_s == %04x",
 					(unsigned long)ino,
 					le16_to_cpu(fnode->ea_offs), le16_to_cpu(fnode->ea_size_s));
 				goto bail;
 			}
 			ea = fnode_ea(fnode);
 			ea_end = fnode_end_ea(fnode);
 			while (ea != ea_end) {
 				if (ea > ea_end) {
 					hpfs_error(s, "bad EA in fnode %08lx",
 						(unsigned long)ino);
 					goto bail;
 				}
 				ea = next_ea(ea);
 			}
 		}
 	}
 	return fnode;
 	bail:
 	brelse(*bhp);
 	return NULL;
 }

 struct anode *hpfs_map_anode(struct super_block *s, anode_secno ano, struct buffer_head **bhp)
 {
 	struct anode *anode;
 	if (hpfs_sb(s)->sb_chk) if (hpfs_chk_sectors(s, ano, 1, "anode")) return NULL;
 	if ((anode = hpfs_map_sector(s, ano, bhp, ANODE_RD_AHEAD)))
 		if (hpfs_sb(s)->sb_chk) {
 			if (le32_to_cpu(anode->magic) != ANODE_MAGIC) {
 				hpfs_error(s, "bad magic on anode %08x", ano);
 				goto bail;
 			}
 			if (le32_to_cpu(anode->self) != ano) {
 				hpfs_error(s, "self pointer invalid on anode %08x", ano);
 				goto bail;
 			}
 			if ((unsigned)anode->btree.n_used_nodes + (unsigned)anode->btree.n_free_nodes !=
 			    (bp_internal(&anode->btree) ? 60 : 40)) {
 				hpfs_error(s, "bad number of nodes in anode %08x", ano);
 				goto bail;
 			}
 			if (le16_to_cpu(anode->btree.first_free) !=
 			    8 + anode->btree.n_used_nodes * (bp_internal(&anode->btree) ? 8 : 12)) {
 				hpfs_error(s, "bad first_free pointer in anode %08x", ano);
 				goto bail;
 			}
 		}
 	return anode;
 	bail:
 	brelse(*bhp);
 	return NULL;
 }

 /*
  * Load dnode to memory and do some checks
  */

 struct dnode *hpfs_map_dnode(struct super_block *s, unsigned secno,
 			     struct quad_buffer_head *qbh)
 {
 	struct dnode *dnode;
 	if (hpfs_sb(s)->sb_chk) {
 		if (hpfs_chk_sectors(s, secno, 4, "dnode")) return NULL;
 		if (secno & 3) {
 			hpfs_error(s, "dnode %08x not byte-aligned", secno);
 			return NULL;
 		}
 	}
 	if ((dnode = hpfs_map_4sectors(s, secno, qbh, DNODE_RD_AHEAD)))
 		if (hpfs_sb(s)->sb_chk) {
 			unsigned p, pp = 0;
 			unsigned char *d = (unsigned char *)dnode;
 			int b = 0;
 			if (le32_to_cpu(dnode->magic) != DNODE_MAGIC) {
 				hpfs_error(s, "bad magic on dnode %08x", secno);
 				goto bail;
 			}
 			if (le32_to_cpu(dnode->self) != secno)
 				hpfs_error(s, "bad self pointer on dnode %08x self = %08x", secno, le32_to_cpu(dnode->self));
 			/* Check dirents - bad dirents would cause infinite
 			   loops or shooting to memory */
 			if (le32_to_cpu(dnode->first_free) > 2048) {
 				hpfs_error(s, "dnode %08x has first_free == %08x", secno, le32_to_cpu(dnode->first_free));
 				goto bail;
 			}
 			for (p = 20; p < le32_to_cpu(dnode->first_free); p += d[p] + (d[p+1] << 8)) {
 				struct hpfs_dirent *de = (struct hpfs_dirent *)((char *)dnode + p);
 				if (le16_to_cpu(de->length) > 292 || (le16_to_cpu(de->length) < 32) || (le16_to_cpu(de->length) & 3) || p + le16_to_cpu(de->length) > 2048) {
 					hpfs_error(s, "bad dirent size in dnode %08x, dirent %03x, last %03x", secno, p, pp);
 					goto bail;
 				}
 				if (((31 + de->namelen + de->down*4 + 3) & ~3) != le16_to_cpu(de->length)) {
 					if (((31 + de->namelen + de->down*4 + 3) & ~3) < le16_to_cpu(de->length) && s->s_flags & MS_RDONLY) goto ok;
 					hpfs_error(s, "namelen does not match dirent size in dnode %08x, dirent %03x, last %03x", secno, p, pp);
 					goto bail;
 				}
 				ok:
 				if (hpfs_sb(s)->sb_chk >= 2) b |= 1 << de->down;
 				if (de->down) if (de_down_pointer(de) < 0x10) {
 					hpfs_error(s, "bad down pointer in dnode %08x, dirent %03x, last %03x", secno, p, pp);
 					goto bail;
 				}
 				pp = p;

 			}
 			if (p != le32_to_cpu(dnode->first_free)) {
 				hpfs_error(s, "size on last dirent does not match first_free; dnode %08x", secno);
 				goto bail;
 			}
 			if (d[pp + 30] != 1 || d[pp + 31] != 255) {
 				hpfs_error(s, "dnode %08x does not end with \\377 entry", secno);
 				goto bail;
 			}
 			if (b == 3)
 				pr_err("unbalanced dnode tree, dnode %08x; see hpfs.txt 4 more info\n",
 					secno);
 		}
 	return dnode;
 	bail:
 	hpfs_brelse4(qbh);
 	return NULL;
 }

 dnode_secno hpfs_fnode_dno(struct super_block *s, ino_t ino)
 {
 	struct buffer_head *bh;
 	struct fnode *fnode;
 	dnode_secno dno;

 	fnode = hpfs_map_fnode(s, ino, &bh);
 	if (!fnode)
 		return 0;

 	dno = le32_to_cpu(fnode->u.external[0].disk_secno);
 	brelse(bh);
 	return dno;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* linux/fs/hpfs/map.c
	*
	* Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999
	*
	* mapping structures to memory with some minimal checks
	*/

	#include "hpfs_fn.h"

	__le32 hpfs_map_dnode_bitmap(struct super_block s, struct quad_buffer_head *qbh)
	{
	return hpfs_map_4sectors(s, hpfs_sb(s)->sb_dmap, qbh, 0);
	}

	__le32 hpfs_map_bitmap(struct super_block s, unsigned bmp_block,
	struct quad_buffer_head qbh, char id)
	{
	secno sec;
	__le32 *ret;
	unsigned n_bands = (hpfs_sb(s)->sb_fs_size + 0x3fff) >> 14;
	if (hpfs_sb(s)->sb_chk) if (bmp_block >= n_bands) {
	hpfs_error(s, "hpfs_map_bitmap called with bad parameter: %08x at %s", bmp_block, id);
	return NULL;
	}
	sec = le32_to_cpu(hpfs_sb(s)->sb_bmp_dir[bmp_block]);
	if (!sec \|\| sec > hpfs_sb(s)->sb_fs_size-4) {
	hpfs_error(s, "invalid bitmap block pointer %08x -> %08x at %s", bmp_block, sec, id);
	return NULL;
	}
	ret = hpfs_map_4sectors(s, sec, qbh, 4);
	if (ret) hpfs_prefetch_bitmap(s, bmp_block + 1);
	return ret;
	}

	void hpfs_prefetch_bitmap(struct super_block *s, unsigned bmp_block)
	{
	unsigned to_prefetch, next_prefetch;
	unsigned n_bands = (hpfs_sb(s)->sb_fs_size + 0x3fff) >> 14;
	if (unlikely(bmp_block >= n_bands))
	return;
	to_prefetch = le32_to_cpu(hpfs_sb(s)->sb_bmp_dir[bmp_block]);
	if (unlikely(bmp_block + 1 >= n_bands))
	next_prefetch = 0;
	else
	next_prefetch = le32_to_cpu(hpfs_sb(s)->sb_bmp_dir[bmp_block + 1]);
	hpfs_prefetch_sectors(s, to_prefetch, 4 + 4 * (to_prefetch + 4 == next_prefetch));
	}

	/*
	* Load first code page into kernel memory, return pointer to 256-byte array,
	* first 128 bytes are uppercasing table for chars 128-255, next 128 bytes are
	* lowercasing table
	*/

	unsigned char hpfs_load_code_page(struct super_block s, secno cps)
	{
	struct buffer_head *bh;
	secno cpds;
	unsigned cpi;
	unsigned char *ptr;
	unsigned char *cp_table;
	int i;
	struct code_page_data *cpd;
	struct code_page_directory *cp = hpfs_map_sector(s, cps, &bh, 0);
	if (!cp) return NULL;
	if (le32_to_cpu(cp->magic) != CP_DIR_MAGIC) {
	pr_err("Code page directory magic doesn't match (magic = %08x)\n",
	le32_to_cpu(cp->magic));
	brelse(bh);
	return NULL;
	}
	if (!le32_to_cpu(cp->n_code_pages)) {
	pr_err("n_code_pages == 0\n");
	brelse(bh);
	return NULL;
	}
	cpds = le32_to_cpu(cp->array[0].code_page_data);
	cpi = le16_to_cpu(cp->array[0].index);
	brelse(bh);

	if (cpi >= 3) {
	pr_err("Code page index out of array\n");
	return NULL;
	}

	if (!(cpd = hpfs_map_sector(s, cpds, &bh, 0))) return NULL;
	if (le16_to_cpu(cpd->offs[cpi]) > 0x178) {
	pr_err("Code page index out of sector\n");
	brelse(bh);
	return NULL;
	}
	ptr = (unsigned char *)cpd + le16_to_cpu(cpd->offs[cpi]) + 6;
	if (!(cp_table = kmalloc(256, GFP_KERNEL))) {
	pr_err("out of memory for code page table\n");
	brelse(bh);
	return NULL;
	}
	memcpy(cp_table, ptr, 128);
	brelse(bh);

	/* Try to build lowercasing table from uppercasing one */

	for (i=128; i<256; i++) cp_table[i]=i;
	for (i=128; i<256; i++) if (cp_table[i-128]!=i && cp_table[i-128]>=128)
	cp_table[cp_table[i-128]] = i;

	return cp_table;
	}

	__le32 hpfs_load_bitmap_directory(struct super_block s, secno bmp)
	{
	struct buffer_head *bh;
	int n = (hpfs_sb(s)->sb_fs_size + 0x200000 - 1) >> 21;
	int i;
	__le32 *b;
	if (!(b = kmalloc(n * 512, GFP_KERNEL))) {
	pr_err("can't allocate memory for bitmap directory\n");
	return NULL;
	}
	for (i=0;i<n;i++) {
	__le32 *d = hpfs_map_sector(s, bmp+i, &bh, n - i - 1);
	if (!d) {
	kfree(b);
	return NULL;
	}
	memcpy((char )b + 512 i, d, 512);
	brelse(bh);
	}
	return b;
	}

	void hpfs_load_hotfix_map(struct super_block s, struct hpfs_spare_block spareblock)
	{
	struct quad_buffer_head qbh;
	__le32 *directory;
	u32 n_hotfixes, n_used_hotfixes;
	unsigned i;

	n_hotfixes = le32_to_cpu(spareblock->n_spares);
	n_used_hotfixes = le32_to_cpu(spareblock->n_spares_used);

	if (n_hotfixes > 256 \|\| n_used_hotfixes > n_hotfixes) {
	hpfs_error(s, "invalid number of hotfixes: %u, used: %u", n_hotfixes, n_used_hotfixes);
	return;
	}
	if (!(directory = hpfs_map_4sectors(s, le32_to_cpu(spareblock->hotfix_map), &qbh, 0))) {
	hpfs_error(s, "can't load hotfix map");
	return;
	}
	for (i = 0; i < n_used_hotfixes; i++) {
	hpfs_sb(s)->hotfix_from[i] = le32_to_cpu(directory[i]);
	hpfs_sb(s)->hotfix_to[i] = le32_to_cpu(directory[n_hotfixes + i]);
	}
	hpfs_sb(s)->n_hotfixes = n_used_hotfixes;
	hpfs_brelse4(&qbh);
	}

	/*
	* Load fnode to memory
	*/

	struct fnode hpfs_map_fnode(struct super_block s, ino_t ino, struct buffer_head **bhp)
	{
	struct fnode *fnode;
	if (hpfs_sb(s)->sb_chk) if (hpfs_chk_sectors(s, ino, 1, "fnode")) {
	return NULL;
	}
	if ((fnode = hpfs_map_sector(s, ino, bhp, FNODE_RD_AHEAD))) {
	if (hpfs_sb(s)->sb_chk) {
	struct extended_attribute *ea;
	struct extended_attribute *ea_end;
	if (le32_to_cpu(fnode->magic) != FNODE_MAGIC) {
	hpfs_error(s, "bad magic on fnode %08lx",
	(unsigned long)ino);
	goto bail;
	}
	if (!fnode_is_dir(fnode)) {
	if ((unsigned)fnode->btree.n_used_nodes + (unsigned)fnode->btree.n_free_nodes !=
	(bp_internal(&fnode->btree) ? 12 : 8)) {
	hpfs_error(s,
	"bad number of nodes in fnode %08lx",
	(unsigned long)ino);
	goto bail;
	}
	if (le16_to_cpu(fnode->btree.first_free) !=
	8 + fnode->btree.n_used_nodes * (bp_internal(&fnode->btree) ? 8 : 12)) {
	hpfs_error(s,
	"bad first_free pointer in fnode %08lx",
	(unsigned long)ino);
	goto bail;
	}
	}
	if (le16_to_cpu(fnode->ea_size_s) && (le16_to_cpu(fnode->ea_offs) < 0xc4 \|\|
	le16_to_cpu(fnode->ea_offs) + le16_to_cpu(fnode->acl_size_s) + le16_to_cpu(fnode->ea_size_s) > 0x200)) {
	hpfs_error(s,
	"bad EA info in fnode %08lx: ea_offs == %04x ea_size_s == %04x",
	(unsigned long)ino,
	le16_to_cpu(fnode->ea_offs), le16_to_cpu(fnode->ea_size_s));
	goto bail;
	}
	ea = fnode_ea(fnode);
	ea_end = fnode_end_ea(fnode);
	while (ea != ea_end) {
	if (ea > ea_end) {
	hpfs_error(s, "bad EA in fnode %08lx",
	(unsigned long)ino);
	goto bail;
	}
	ea = next_ea(ea);
	}
	}
	}
	return fnode;
	bail:
	brelse(*bhp);
	return NULL;
	}

	struct anode hpfs_map_anode(struct super_block s, anode_secno ano, struct buffer_head **bhp)
	{
	struct anode *anode;
	if (hpfs_sb(s)->sb_chk) if (hpfs_chk_sectors(s, ano, 1, "anode")) return NULL;
	if ((anode = hpfs_map_sector(s, ano, bhp, ANODE_RD_AHEAD)))
	if (hpfs_sb(s)->sb_chk) {
	if (le32_to_cpu(anode->magic) != ANODE_MAGIC) {
	hpfs_error(s, "bad magic on anode %08x", ano);
	goto bail;
	}
	if (le32_to_cpu(anode->self) != ano) {
	hpfs_error(s, "self pointer invalid on anode %08x", ano);
	goto bail;
	}
	if ((unsigned)anode->btree.n_used_nodes + (unsigned)anode->btree.n_free_nodes !=
	(bp_internal(&anode->btree) ? 60 : 40)) {
	hpfs_error(s, "bad number of nodes in anode %08x", ano);
	goto bail;
	}
	if (le16_to_cpu(anode->btree.first_free) !=
	8 + anode->btree.n_used_nodes * (bp_internal(&anode->btree) ? 8 : 12)) {
	hpfs_error(s, "bad first_free pointer in anode %08x", ano);
	goto bail;
	}
	}
	return anode;
	bail:
	brelse(*bhp);
	return NULL;
	}

	/*
	* Load dnode to memory and do some checks
	*/

	struct dnode hpfs_map_dnode(struct super_block s, unsigned secno,
	struct quad_buffer_head *qbh)
	{
	struct dnode *dnode;
	if (hpfs_sb(s)->sb_chk) {
	if (hpfs_chk_sectors(s, secno, 4, "dnode")) return NULL;
	if (secno & 3) {
	hpfs_error(s, "dnode %08x not byte-aligned", secno);
	return NULL;
	}
	}
	if ((dnode = hpfs_map_4sectors(s, secno, qbh, DNODE_RD_AHEAD)))
	if (hpfs_sb(s)->sb_chk) {
	unsigned p, pp = 0;
	unsigned char d = (unsigned char )dnode;
	int b = 0;
	if (le32_to_cpu(dnode->magic) != DNODE_MAGIC) {
	hpfs_error(s, "bad magic on dnode %08x", secno);
	goto bail;
	}
	if (le32_to_cpu(dnode->self) != secno)
	hpfs_error(s, "bad self pointer on dnode %08x self = %08x", secno, le32_to_cpu(dnode->self));
	/* Check dirents - bad dirents would cause infinite
	loops or shooting to memory */
	if (le32_to_cpu(dnode->first_free) > 2048) {
	hpfs_error(s, "dnode %08x has first_free == %08x", secno, le32_to_cpu(dnode->first_free));
	goto bail;
	}
	for (p = 20; p < le32_to_cpu(dnode->first_free); p += d[p] + (d[p+1] << 8)) {
	struct hpfs_dirent de = (struct hpfs_dirent )((char *)dnode + p);
	if (le16_to_cpu(de->length) > 292 \|\| (le16_to_cpu(de->length) < 32) \|\| (le16_to_cpu(de->length) & 3) \|\| p + le16_to_cpu(de->length) > 2048) {
	hpfs_error(s, "bad dirent size in dnode %08x, dirent %03x, last %03x", secno, p, pp);
	goto bail;
	}
	if (((31 + de->namelen + de->down*4 + 3) & ~3) != le16_to_cpu(de->length)) {
	if (((31 + de->namelen + de->down*4 + 3) & ~3) < le16_to_cpu(de->length) && s->s_flags & MS_RDONLY) goto ok;
	hpfs_error(s, "namelen does not match dirent size in dnode %08x, dirent %03x, last %03x", secno, p, pp);
	goto bail;
	}
	ok:
	if (hpfs_sb(s)->sb_chk >= 2) b \|= 1 << de->down;
	if (de->down) if (de_down_pointer(de) < 0x10) {
	hpfs_error(s, "bad down pointer in dnode %08x, dirent %03x, last %03x", secno, p, pp);
	goto bail;
	}
	pp = p;

	}
	if (p != le32_to_cpu(dnode->first_free)) {
	hpfs_error(s, "size on last dirent does not match first_free; dnode %08x", secno);
	goto bail;
	}
	if (d[pp + 30] != 1 \|\| d[pp + 31] != 255) {
	hpfs_error(s, "dnode %08x does not end with \\377 entry", secno);
	goto bail;
	}
	if (b == 3)
	pr_err("unbalanced dnode tree, dnode %08x; see hpfs.txt 4 more info\n",
	secno);
	}
	return dnode;
	bail:
	hpfs_brelse4(qbh);
	return NULL;
	}

	dnode_secno hpfs_fnode_dno(struct super_block *s, ino_t ino)
	{
	struct buffer_head *bh;
	struct fnode *fnode;
	dnode_secno dno;

	fnode = hpfs_map_fnode(s, ino, &bh);
	if (!fnode)
	return 0;

	dno = le32_to_cpu(fnode->u.external[0].disk_secno);
	brelse(bh);
	return dno;
	}