fs/udf/directory.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * directory.c
  *
  * PURPOSE
  *	Directory related functions
  *
  */

 #include "udfdecl.h"
 #include "udf_i.h"

 #include <linux/fs.h>
 #include <linux/string.h>
 #include <linux/bio.h>
 #include <linux/crc-itu-t.h>
 #include <linux/iversion.h>

 static int udf_verify_fi(struct udf_fileident_iter *iter)
 {
 	unsigned int len;

 	if (iter->fi.descTag.tagIdent != cpu_to_le16(TAG_IDENT_FID)) {
 		udf_err(iter->dir->i_sb,
 			"directory (ino %lu) has entry at pos %llu with incorrect tag %x\n",
 			iter->dir->i_ino, (unsigned long long)iter->pos,
 			le16_to_cpu(iter->fi.descTag.tagIdent));
 		return -EFSCORRUPTED;
 	}
 	len = udf_dir_entry_len(&iter->fi);
 	if (le16_to_cpu(iter->fi.lengthOfImpUse) & 3) {
 		udf_err(iter->dir->i_sb,
 			"directory (ino %lu) has entry at pos %llu with unaligned length of impUse field\n",
 			iter->dir->i_ino, (unsigned long long)iter->pos);
 		return -EFSCORRUPTED;
 	}
 	/*
 	 * This is in fact allowed by the spec due to long impUse field but
 	 * we don't support it. If there is real media with this large impUse
 	 * field, support can be added.
 	 */
 	if (len > 1 << iter->dir->i_blkbits) {
 		udf_err(iter->dir->i_sb,
 			"directory (ino %lu) has too big (%u) entry at pos %llu\n",
 			iter->dir->i_ino, len, (unsigned long long)iter->pos);
 		return -EFSCORRUPTED;
 	}
 	if (iter->pos + len > iter->dir->i_size) {
 		udf_err(iter->dir->i_sb,
 			"directory (ino %lu) has entry past directory size at pos %llu\n",
 			iter->dir->i_ino, (unsigned long long)iter->pos);
 		return -EFSCORRUPTED;
 	}
 	if (udf_dir_entry_len(&iter->fi) !=
 	    sizeof(struct tag) + le16_to_cpu(iter->fi.descTag.descCRCLength)) {
 		udf_err(iter->dir->i_sb,
 			"directory (ino %lu) has entry where CRC length (%u) does not match entry length (%u)\n",
 			iter->dir->i_ino,
 			(unsigned)le16_to_cpu(iter->fi.descTag.descCRCLength),
 			(unsigned)(udf_dir_entry_len(&iter->fi) -
 							sizeof(struct tag)));
 		return -EFSCORRUPTED;
 	}
 	return 0;
 }

 static int udf_copy_fi(struct udf_fileident_iter *iter)
 {
 	struct udf_inode_info *iinfo = UDF_I(iter->dir);
 	u32 blksize = 1 << iter->dir->i_blkbits;
 	u32 off, len, nameoff;
 	int err;

 	/* Skip copying when we are at EOF */
 	if (iter->pos >= iter->dir->i_size) {
 		iter->name = NULL;
 		return 0;
 	}
 	if (iter->dir->i_size < iter->pos + sizeof(struct fileIdentDesc)) {
 		udf_err(iter->dir->i_sb,
 			"directory (ino %lu) has entry straddling EOF\n",
 			iter->dir->i_ino);
 		return -EFSCORRUPTED;
 	}
 	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
 		memcpy(&iter->fi, iinfo->i_data + iinfo->i_lenEAttr + iter->pos,
 		       sizeof(struct fileIdentDesc));
 		err = udf_verify_fi(iter);
 		if (err < 0)
 			return err;
 		iter->name = iinfo->i_data + iinfo->i_lenEAttr + iter->pos +
 			sizeof(struct fileIdentDesc) +
 			le16_to_cpu(iter->fi.lengthOfImpUse);
 		return 0;
 	}

 	off = iter->pos & (blksize - 1);
 	len = min_t(u32, sizeof(struct fileIdentDesc), blksize - off);
 	memcpy(&iter->fi, iter->bh[0]->b_data + off, len);
 	if (len < sizeof(struct fileIdentDesc))
 		memcpy((char *)(&iter->fi) + len, iter->bh[1]->b_data,
 		       sizeof(struct fileIdentDesc) - len);
 	err = udf_verify_fi(iter);
 	if (err < 0)
 		return err;

 	/* Handle directory entry name */
 	nameoff = off + sizeof(struct fileIdentDesc) +
 				le16_to_cpu(iter->fi.lengthOfImpUse);
 	if (off + udf_dir_entry_len(&iter->fi) <= blksize) {
 		iter->name = iter->bh[0]->b_data + nameoff;
 	} else if (nameoff >= blksize) {
 		iter->name = iter->bh[1]->b_data + (nameoff - blksize);
 	} else {
 		iter->name = iter->namebuf;
 		len = blksize - nameoff;
 		memcpy(iter->name, iter->bh[0]->b_data + nameoff, len);
 		memcpy(iter->name + len, iter->bh[1]->b_data,
 		       iter->fi.lengthFileIdent - len);
 	}
 	return 0;
 }

 /* Readahead 8k once we are at 8k boundary */
 static void udf_readahead_dir(struct udf_fileident_iter *iter)
 {
 	unsigned int ralen = 16 >> (iter->dir->i_blkbits - 9);
 	struct buffer_head *tmp, *bha[16];
 	int i, num;
 	udf_pblk_t blk;

 	if (iter->loffset & (ralen - 1))
 		return;

 	if (iter->loffset + ralen > (iter->elen >> iter->dir->i_blkbits))
 		ralen = (iter->elen >> iter->dir->i_blkbits) - iter->loffset;
 	num = 0;
 	for (i = 0; i < ralen; i++) {
 		blk = udf_get_lb_pblock(iter->dir->i_sb, &iter->eloc,
 					iter->loffset + i);
 		tmp = sb_getblk(iter->dir->i_sb, blk);
 		if (tmp && !buffer_uptodate(tmp) && !buffer_locked(tmp))
 			bha[num++] = tmp;
 		else
 			brelse(tmp);
 	}
 	if (num) {
 		bh_readahead_batch(num, bha, REQ_RAHEAD);
 		for (i = 0; i < num; i++)
 			brelse(bha[i]);
 	}
 }

 static struct buffer_head *udf_fiiter_bread_blk(struct udf_fileident_iter *iter)
 {
 	udf_pblk_t blk;

 	udf_readahead_dir(iter);
 	blk = udf_get_lb_pblock(iter->dir->i_sb, &iter->eloc, iter->loffset);
 	return sb_bread(iter->dir->i_sb, blk);
 }

 /*
  * Updates loffset to point to next directory block; eloc, elen & epos are
  * updated if we need to traverse to the next extent as well.
  */
 static int udf_fiiter_advance_blk(struct udf_fileident_iter *iter)
 {
 	int8_t etype = -1;
 	int err = 0;

 	iter->loffset++;
 	if (iter->loffset < DIV_ROUND_UP(iter->elen, 1<<iter->dir->i_blkbits))
 		return 0;

 	iter->loffset = 0;
 	err = udf_next_aext(iter->dir, &iter->epos, &iter->eloc,
 			    &iter->elen, &etype, 1);
 	if (err < 0)
 		return err;
 	else if (err == 0 || etype != (EXT_RECORDED_ALLOCATED >> 30)) {
 		if (iter->pos == iter->dir->i_size) {
 			iter->elen = 0;
 			return 0;
 		}
 		udf_err(iter->dir->i_sb,
 			"extent after position %llu not allocated in directory (ino %lu)\n",
 			(unsigned long long)iter->pos, iter->dir->i_ino);
 		return -EFSCORRUPTED;
 	}
 	return 0;
 }

 static int udf_fiiter_load_bhs(struct udf_fileident_iter *iter)
 {
 	int blksize = 1 << iter->dir->i_blkbits;
 	int off = iter->pos & (blksize - 1);
 	int err;
 	struct fileIdentDesc *fi;

 	/* Is there any further extent we can map from? */
 	if (!iter->bh[0] && iter->elen) {
 		iter->bh[0] = udf_fiiter_bread_blk(iter);
 		if (!iter->bh[0]) {
 			err = -ENOMEM;
 			goto out_brelse;
 		}
 		if (!buffer_uptodate(iter->bh[0])) {
 			err = -EIO;
 			goto out_brelse;
 		}
 	}
 	/* There's no next block so we are done */
 	if (iter->pos >= iter->dir->i_size)
 		return 0;
 	/* Need to fetch next block as well? */
 	if (off + sizeof(struct fileIdentDesc) > blksize)
 		goto fetch_next;
 	fi = (struct fileIdentDesc *)(iter->bh[0]->b_data + off);
 	/* Need to fetch next block to get name? */
 	if (off + udf_dir_entry_len(fi) > blksize) {
 fetch_next:
 		err = udf_fiiter_advance_blk(iter);
 		if (err)
 			goto out_brelse;
 		iter->bh[1] = udf_fiiter_bread_blk(iter);
 		if (!iter->bh[1]) {
 			err = -ENOMEM;
 			goto out_brelse;
 		}
 		if (!buffer_uptodate(iter->bh[1])) {
 			err = -EIO;
 			goto out_brelse;
 		}
 	}
 	return 0;
 out_brelse:
 	brelse(iter->bh[0]);
 	brelse(iter->bh[1]);
 	iter->bh[0] = iter->bh[1] = NULL;
 	return err;
 }

 int udf_fiiter_init(struct udf_fileident_iter *iter, struct inode *dir,
 		    loff_t pos)
 {
 	struct udf_inode_info *iinfo = UDF_I(dir);
 	int err = 0;
 	int8_t etype;

 	iter->dir = dir;
 	iter->bh[0] = iter->bh[1] = NULL;
 	iter->pos = pos;
 	iter->elen = 0;
 	iter->epos.bh = NULL;
 	iter->name = NULL;
 	/*
 	 * When directory is verified, we don't expect directory iteration to
 	 * fail and it can be difficult to undo without corrupting filesystem.
 	 * So just do not allow memory allocation failures here.
 	 */
 	iter->namebuf = kmalloc(UDF_NAME_LEN_CS0, GFP_KERNEL | __GFP_NOFAIL);

 	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
 		err = udf_copy_fi(iter);
 		goto out;
 	}

 	err = inode_bmap(dir, iter->pos >> dir->i_blkbits, &iter->epos,
 			 &iter->eloc, &iter->elen, &iter->loffset, &etype);
 	if (err <= 0 || etype != (EXT_RECORDED_ALLOCATED >> 30)) {
 		if (pos == dir->i_size)
 			return 0;
 		udf_err(dir->i_sb,
 			"position %llu not allocated in directory (ino %lu)\n",
 			(unsigned long long)pos, dir->i_ino);
 		err = -EFSCORRUPTED;
 		goto out;
 	}
 	err = udf_fiiter_load_bhs(iter);
 	if (err < 0)
 		goto out;
 	err = udf_copy_fi(iter);
 out:
 	if (err < 0)
 		udf_fiiter_release(iter);
 	return err;
 }

 int udf_fiiter_advance(struct udf_fileident_iter *iter)
 {
 	unsigned int oldoff, len;
 	int blksize = 1 << iter->dir->i_blkbits;
 	int err;

 	oldoff = iter->pos & (blksize - 1);
 	len = udf_dir_entry_len(&iter->fi);
 	iter->pos += len;
 	if (UDF_I(iter->dir)->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB) {
 		if (oldoff + len >= blksize) {
 			brelse(iter->bh[0]);
 			iter->bh[0] = NULL;
 			/* Next block already loaded? */
 			if (iter->bh[1]) {
 				iter->bh[0] = iter->bh[1];
 				iter->bh[1] = NULL;
 			} else {
 				err = udf_fiiter_advance_blk(iter);
 				if (err < 0)
 					return err;
 			}
 		}
 		err = udf_fiiter_load_bhs(iter);
 		if (err < 0)
 			return err;
 	}
 	return udf_copy_fi(iter);
 }

 void udf_fiiter_release(struct udf_fileident_iter *iter)
 {
 	iter->dir = NULL;
 	brelse(iter->bh[0]);
 	brelse(iter->bh[1]);
 	iter->bh[0] = iter->bh[1] = NULL;
 	kfree(iter->namebuf);
 	iter->namebuf = NULL;
 }

 static void udf_copy_to_bufs(void *buf1, int len1, void *buf2, int len2,
 			     int off, void *src, int len)
 {
 	int copy;

 	if (off >= len1) {
 		off -= len1;
 	} else {
 		copy = min(off + len, len1) - off;
 		memcpy(buf1 + off, src, copy);
 		src += copy;
 		len -= copy;
 		off = 0;
 	}
 	if (len > 0) {
 		if (WARN_ON_ONCE(off + len > len2 || !buf2))
 			return;
 		memcpy(buf2 + off, src, len);
 	}
 }

 static uint16_t udf_crc_fi_bufs(void *buf1, int len1, void *buf2, int len2,
 				int off, int len)
 {
 	int copy;
 	uint16_t crc = 0;

 	if (off >= len1) {
 		off -= len1;
 	} else {
 		copy = min(off + len, len1) - off;
 		crc = crc_itu_t(crc, buf1 + off, copy);
 		len -= copy;
 		off = 0;
 	}
 	if (len > 0) {
 		if (WARN_ON_ONCE(off + len > len2 || !buf2))
 			return 0;
 		crc = crc_itu_t(crc, buf2 + off, len);
 	}
 	return crc;
 }

 static void udf_copy_fi_to_bufs(char *buf1, int len1, char *buf2, int len2,
 				int off, struct fileIdentDesc *fi,
 				uint8_t *impuse, uint8_t *name)
 {
 	uint16_t crc;
 	int fioff = off;
 	int crcoff = off + sizeof(struct tag);
 	unsigned int crclen = udf_dir_entry_len(fi) - sizeof(struct tag);
 	char zeros[UDF_NAME_PAD] = {};
 	int endoff = off + udf_dir_entry_len(fi);

 	udf_copy_to_bufs(buf1, len1, buf2, len2, off, fi,
 			 sizeof(struct fileIdentDesc));
 	off += sizeof(struct fileIdentDesc);
 	if (impuse)
 		udf_copy_to_bufs(buf1, len1, buf2, len2, off, impuse,
 				 le16_to_cpu(fi->lengthOfImpUse));
 	off += le16_to_cpu(fi->lengthOfImpUse);
 	if (name) {
 		udf_copy_to_bufs(buf1, len1, buf2, len2, off, name,
 				 fi->lengthFileIdent);
 		off += fi->lengthFileIdent;
 		udf_copy_to_bufs(buf1, len1, buf2, len2, off, zeros,
 				 endoff - off);
 	}

 	crc = udf_crc_fi_bufs(buf1, len1, buf2, len2, crcoff, crclen);
 	fi->descTag.descCRC = cpu_to_le16(crc);
 	fi->descTag.descCRCLength = cpu_to_le16(crclen);
 	fi->descTag.tagChecksum = udf_tag_checksum(&fi->descTag);

 	udf_copy_to_bufs(buf1, len1, buf2, len2, fioff, fi, sizeof(struct tag));
 }

 void udf_fiiter_write_fi(struct udf_fileident_iter *iter, uint8_t *impuse)
 {
 	struct udf_inode_info *iinfo = UDF_I(iter->dir);
 	void *buf1, *buf2 = NULL;
 	int len1, len2 = 0, off;
 	int blksize = 1 << iter->dir->i_blkbits;

 	off = iter->pos & (blksize - 1);
 	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
 		buf1 = iinfo->i_data + iinfo->i_lenEAttr;
 		len1 = iter->dir->i_size;
 	} else {
 		buf1 = iter->bh[0]->b_data;
 		len1 = blksize;
 		if (iter->bh[1]) {
 			buf2 = iter->bh[1]->b_data;
 			len2 = blksize;
 		}
 	}

 	udf_copy_fi_to_bufs(buf1, len1, buf2, len2, off, &iter->fi, impuse,
 			    iter->name == iter->namebuf ? iter->name : NULL);

 	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
 		mark_inode_dirty(iter->dir);
 	} else {
 		mark_buffer_dirty_inode(iter->bh[0], iter->dir);
 		if (iter->bh[1])
 			mark_buffer_dirty_inode(iter->bh[1], iter->dir);
 	}
 	inode_inc_iversion(iter->dir);
 }

 void udf_fiiter_update_elen(struct udf_fileident_iter *iter, uint32_t new_elen)
 {
 	struct udf_inode_info *iinfo = UDF_I(iter->dir);
 	int diff = new_elen - iter->elen;

 	/* Skip update when we already went past the last extent */
 	if (!iter->elen)
 		return;
 	iter->elen = new_elen;
 	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
 		iter->epos.offset -= sizeof(struct short_ad);
 	else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
 		iter->epos.offset -= sizeof(struct long_ad);
 	udf_write_aext(iter->dir, &iter->epos, &iter->eloc, iter->elen, 1);
 	iinfo->i_lenExtents += diff;
 	mark_inode_dirty(iter->dir);
 }

 /* Append new block to directory. @iter is expected to point at EOF */
 int udf_fiiter_append_blk(struct udf_fileident_iter *iter)
 {
 	struct udf_inode_info *iinfo = UDF_I(iter->dir);
 	int blksize = 1 << iter->dir->i_blkbits;
 	struct buffer_head *bh;
 	sector_t block;
 	uint32_t old_elen = iter->elen;
 	int err;
 	int8_t etype;

 	if (WARN_ON_ONCE(iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB))
 		return -EINVAL;

 	/* Round up last extent in the file */
 	udf_fiiter_update_elen(iter, ALIGN(iter->elen, blksize));

 	/* Allocate new block and refresh mapping information */
 	block = iinfo->i_lenExtents >> iter->dir->i_blkbits;
 	bh = udf_bread(iter->dir, block, 1, &err);
 	if (!bh) {
 		udf_fiiter_update_elen(iter, old_elen);
 		return err;
 	}
 	err = inode_bmap(iter->dir, block, &iter->epos, &iter->eloc, &iter->elen,
 		   &iter->loffset, &etype);
 	if (err <= 0 || etype != (EXT_RECORDED_ALLOCATED >> 30)) {
 		udf_err(iter->dir->i_sb,
 			"block %llu not allocated in directory (ino %lu)\n",
 			(unsigned long long)block, iter->dir->i_ino);
 		return -EFSCORRUPTED;
 	}
 	if (!(iter->pos & (blksize - 1))) {
 		brelse(iter->bh[0]);
 		iter->bh[0] = bh;
 	} else {
 		iter->bh[1] = bh;
 	}
 	return 0;
 }

 struct short_ad *udf_get_fileshortad(uint8_t *ptr, int maxoffset, uint32_t *offset,
 			      int inc)
 {
 	struct short_ad *sa;

 	if ((!ptr) || (!offset)) {
 		pr_err("%s: invalidparms\n", __func__);
 		return NULL;
 	}

 	if ((*offset + sizeof(struct short_ad)) > maxoffset)
 		return NULL;
 	else {
 		sa = (struct short_ad *)ptr;
 		if (sa->extLength == 0)
 			return NULL;
 	}

 	if (inc)
 		*offset += sizeof(struct short_ad);
 	return sa;
 }

 struct long_ad *udf_get_filelongad(uint8_t *ptr, int maxoffset, uint32_t *offset, int inc)
 {
 	struct long_ad *la;

 	if ((!ptr) || (!offset)) {
 		pr_err("%s: invalidparms\n", __func__);
 		return NULL;
 	}

 	if ((*offset + sizeof(struct long_ad)) > maxoffset)
 		return NULL;
 	else {
 		la = (struct long_ad *)ptr;
 		if (la->extLength == 0)
 			return NULL;
 	}

 	if (inc)
 		*offset += sizeof(struct long_ad);
 	return la;
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* directory.c
	*
	* PURPOSE
	* Directory related functions
	*
	*/

	#include "udfdecl.h"
	#include "udf_i.h"

	#include <linux/fs.h>
	#include <linux/string.h>
	#include <linux/bio.h>
	#include <linux/crc-itu-t.h>
	#include <linux/iversion.h>

	static int udf_verify_fi(struct udf_fileident_iter *iter)
	{
	unsigned int len;

	if (iter->fi.descTag.tagIdent != cpu_to_le16(TAG_IDENT_FID)) {
	udf_err(iter->dir->i_sb,
	"directory (ino %lu) has entry at pos %llu with incorrect tag %x\n",
	iter->dir->i_ino, (unsigned long long)iter->pos,
	le16_to_cpu(iter->fi.descTag.tagIdent));
	return -EFSCORRUPTED;
	}
	len = udf_dir_entry_len(&iter->fi);
	if (le16_to_cpu(iter->fi.lengthOfImpUse) & 3) {
	udf_err(iter->dir->i_sb,
	"directory (ino %lu) has entry at pos %llu with unaligned length of impUse field\n",
	iter->dir->i_ino, (unsigned long long)iter->pos);
	return -EFSCORRUPTED;
	}
	/*
	* This is in fact allowed by the spec due to long impUse field but
	* we don't support it. If there is real media with this large impUse
	* field, support can be added.
	*/
	if (len > 1 << iter->dir->i_blkbits) {
	udf_err(iter->dir->i_sb,
	"directory (ino %lu) has too big (%u) entry at pos %llu\n",
	iter->dir->i_ino, len, (unsigned long long)iter->pos);
	return -EFSCORRUPTED;
	}
	if (iter->pos + len > iter->dir->i_size) {
	udf_err(iter->dir->i_sb,
	"directory (ino %lu) has entry past directory size at pos %llu\n",
	iter->dir->i_ino, (unsigned long long)iter->pos);
	return -EFSCORRUPTED;
	}
	if (udf_dir_entry_len(&iter->fi) !=
	sizeof(struct tag) + le16_to_cpu(iter->fi.descTag.descCRCLength)) {
	udf_err(iter->dir->i_sb,
	"directory (ino %lu) has entry where CRC length (%u) does not match entry length (%u)\n",
	iter->dir->i_ino,
	(unsigned)le16_to_cpu(iter->fi.descTag.descCRCLength),
	(unsigned)(udf_dir_entry_len(&iter->fi) -
	sizeof(struct tag)));
	return -EFSCORRUPTED;
	}
	return 0;
	}

	static int udf_copy_fi(struct udf_fileident_iter *iter)
	{
	struct udf_inode_info *iinfo = UDF_I(iter->dir);
	u32 blksize = 1 << iter->dir->i_blkbits;
	u32 off, len, nameoff;
	int err;

	/* Skip copying when we are at EOF */
	if (iter->pos >= iter->dir->i_size) {
	iter->name = NULL;
	return 0;
	}
	if (iter->dir->i_size < iter->pos + sizeof(struct fileIdentDesc)) {
	udf_err(iter->dir->i_sb,
	"directory (ino %lu) has entry straddling EOF\n",
	iter->dir->i_ino);
	return -EFSCORRUPTED;
	}
	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
	memcpy(&iter->fi, iinfo->i_data + iinfo->i_lenEAttr + iter->pos,
	sizeof(struct fileIdentDesc));
	err = udf_verify_fi(iter);
	if (err < 0)
	return err;
	iter->name = iinfo->i_data + iinfo->i_lenEAttr + iter->pos +
	sizeof(struct fileIdentDesc) +
	le16_to_cpu(iter->fi.lengthOfImpUse);
	return 0;
	}

	off = iter->pos & (blksize - 1);
	len = min_t(u32, sizeof(struct fileIdentDesc), blksize - off);
	memcpy(&iter->fi, iter->bh[0]->b_data + off, len);
	if (len < sizeof(struct fileIdentDesc))
	memcpy((char *)(&iter->fi) + len, iter->bh[1]->b_data,
	sizeof(struct fileIdentDesc) - len);
	err = udf_verify_fi(iter);
	if (err < 0)
	return err;

	/* Handle directory entry name */
	nameoff = off + sizeof(struct fileIdentDesc) +
	le16_to_cpu(iter->fi.lengthOfImpUse);
	if (off + udf_dir_entry_len(&iter->fi) <= blksize) {
	iter->name = iter->bh[0]->b_data + nameoff;
	} else if (nameoff >= blksize) {
	iter->name = iter->bh[1]->b_data + (nameoff - blksize);
	} else {
	iter->name = iter->namebuf;
	len = blksize - nameoff;
	memcpy(iter->name, iter->bh[0]->b_data + nameoff, len);
	memcpy(iter->name + len, iter->bh[1]->b_data,
	iter->fi.lengthFileIdent - len);
	}
	return 0;
	}

	/* Readahead 8k once we are at 8k boundary */
	static void udf_readahead_dir(struct udf_fileident_iter *iter)
	{
	unsigned int ralen = 16 >> (iter->dir->i_blkbits - 9);
	struct buffer_head tmp, bha[16];
	int i, num;
	udf_pblk_t blk;

	if (iter->loffset & (ralen - 1))
	return;

	if (iter->loffset + ralen > (iter->elen >> iter->dir->i_blkbits))
	ralen = (iter->elen >> iter->dir->i_blkbits) - iter->loffset;
	num = 0;
	for (i = 0; i < ralen; i++) {
	blk = udf_get_lb_pblock(iter->dir->i_sb, &iter->eloc,
	iter->loffset + i);
	tmp = sb_getblk(iter->dir->i_sb, blk);
	if (tmp && !buffer_uptodate(tmp) && !buffer_locked(tmp))
	bha[num++] = tmp;
	else
	brelse(tmp);
	}
	if (num) {
	bh_readahead_batch(num, bha, REQ_RAHEAD);
	for (i = 0; i < num; i++)
	brelse(bha[i]);
	}
	}

	static struct buffer_head udf_fiiter_bread_blk(struct udf_fileident_iter iter)
	{
	udf_pblk_t blk;

	udf_readahead_dir(iter);
	blk = udf_get_lb_pblock(iter->dir->i_sb, &iter->eloc, iter->loffset);
	return sb_bread(iter->dir->i_sb, blk);
	}

	/*
	* Updates loffset to point to next directory block; eloc, elen & epos are
	* updated if we need to traverse to the next extent as well.
	*/
	static int udf_fiiter_advance_blk(struct udf_fileident_iter *iter)
	{
	int8_t etype = -1;
	int err = 0;

	iter->loffset++;
	if (iter->loffset < DIV_ROUND_UP(iter->elen, 1<<iter->dir->i_blkbits))
	return 0;

	iter->loffset = 0;
	err = udf_next_aext(iter->dir, &iter->epos, &iter->eloc,
	&iter->elen, &etype, 1);
	if (err < 0)
	return err;
	else if (err == 0 \|\| etype != (EXT_RECORDED_ALLOCATED >> 30)) {
	if (iter->pos == iter->dir->i_size) {
	iter->elen = 0;
	return 0;
	}
	udf_err(iter->dir->i_sb,
	"extent after position %llu not allocated in directory (ino %lu)\n",
	(unsigned long long)iter->pos, iter->dir->i_ino);
	return -EFSCORRUPTED;
	}
	return 0;
	}

	static int udf_fiiter_load_bhs(struct udf_fileident_iter *iter)
	{
	int blksize = 1 << iter->dir->i_blkbits;
	int off = iter->pos & (blksize - 1);
	int err;
	struct fileIdentDesc *fi;

	/* Is there any further extent we can map from? */
	if (!iter->bh[0] && iter->elen) {
	iter->bh[0] = udf_fiiter_bread_blk(iter);
	if (!iter->bh[0]) {
	err = -ENOMEM;
	goto out_brelse;
	}
	if (!buffer_uptodate(iter->bh[0])) {
	err = -EIO;
	goto out_brelse;
	}
	}
	/* There's no next block so we are done */
	if (iter->pos >= iter->dir->i_size)
	return 0;
	/* Need to fetch next block as well? */
	if (off + sizeof(struct fileIdentDesc) > blksize)
	goto fetch_next;
	fi = (struct fileIdentDesc *)(iter->bh[0]->b_data + off);
	/* Need to fetch next block to get name? */
	if (off + udf_dir_entry_len(fi) > blksize) {
	fetch_next:
	err = udf_fiiter_advance_blk(iter);
	if (err)
	goto out_brelse;
	iter->bh[1] = udf_fiiter_bread_blk(iter);
	if (!iter->bh[1]) {
	err = -ENOMEM;
	goto out_brelse;
	}
	if (!buffer_uptodate(iter->bh[1])) {
	err = -EIO;
	goto out_brelse;
	}
	}
	return 0;
	out_brelse:
	brelse(iter->bh[0]);
	brelse(iter->bh[1]);
	iter->bh[0] = iter->bh[1] = NULL;
	return err;
	}

	int udf_fiiter_init(struct udf_fileident_iter iter, struct inode dir,
	loff_t pos)
	{
	struct udf_inode_info *iinfo = UDF_I(dir);
	int err = 0;
	int8_t etype;

	iter->dir = dir;
	iter->bh[0] = iter->bh[1] = NULL;
	iter->pos = pos;
	iter->elen = 0;
	iter->epos.bh = NULL;
	iter->name = NULL;
	/*
	* When directory is verified, we don't expect directory iteration to
	* fail and it can be difficult to undo without corrupting filesystem.
	* So just do not allow memory allocation failures here.
	*/
	iter->namebuf = kmalloc(UDF_NAME_LEN_CS0, GFP_KERNEL \| __GFP_NOFAIL);

	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
	err = udf_copy_fi(iter);
	goto out;
	}

	err = inode_bmap(dir, iter->pos >> dir->i_blkbits, &iter->epos,
	&iter->eloc, &iter->elen, &iter->loffset, &etype);
	if (err <= 0 \|\| etype != (EXT_RECORDED_ALLOCATED >> 30)) {
	if (pos == dir->i_size)
	return 0;
	udf_err(dir->i_sb,
	"position %llu not allocated in directory (ino %lu)\n",
	(unsigned long long)pos, dir->i_ino);
	err = -EFSCORRUPTED;
	goto out;
	}
	err = udf_fiiter_load_bhs(iter);
	if (err < 0)
	goto out;
	err = udf_copy_fi(iter);
	out:
	if (err < 0)
	udf_fiiter_release(iter);
	return err;
	}

	int udf_fiiter_advance(struct udf_fileident_iter *iter)
	{
	unsigned int oldoff, len;
	int blksize = 1 << iter->dir->i_blkbits;
	int err;

	oldoff = iter->pos & (blksize - 1);
	len = udf_dir_entry_len(&iter->fi);
	iter->pos += len;
	if (UDF_I(iter->dir)->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB) {
	if (oldoff + len >= blksize) {
	brelse(iter->bh[0]);
	iter->bh[0] = NULL;
	/* Next block already loaded? */
	if (iter->bh[1]) {
	iter->bh[0] = iter->bh[1];
	iter->bh[1] = NULL;
	} else {
	err = udf_fiiter_advance_blk(iter);
	if (err < 0)
	return err;
	}
	}
	err = udf_fiiter_load_bhs(iter);
	if (err < 0)
	return err;
	}
	return udf_copy_fi(iter);
	}

	void udf_fiiter_release(struct udf_fileident_iter *iter)
	{
	iter->dir = NULL;
	brelse(iter->bh[0]);
	brelse(iter->bh[1]);
	iter->bh[0] = iter->bh[1] = NULL;
	kfree(iter->namebuf);
	iter->namebuf = NULL;
	}

	static void udf_copy_to_bufs(void buf1, int len1, void buf2, int len2,
	int off, void *src, int len)
	{
	int copy;

	if (off >= len1) {
	off -= len1;
	} else {
	copy = min(off + len, len1) - off;
	memcpy(buf1 + off, src, copy);
	src += copy;
	len -= copy;
	off = 0;
	}
	if (len > 0) {
	if (WARN_ON_ONCE(off + len > len2 \|\| !buf2))
	return;
	memcpy(buf2 + off, src, len);
	}
	}

	static uint16_t udf_crc_fi_bufs(void buf1, int len1, void buf2, int len2,
	int off, int len)
	{
	int copy;
	uint16_t crc = 0;

	if (off >= len1) {
	off -= len1;
	} else {
	copy = min(off + len, len1) - off;
	crc = crc_itu_t(crc, buf1 + off, copy);
	len -= copy;
	off = 0;
	}
	if (len > 0) {
	if (WARN_ON_ONCE(off + len > len2 \|\| !buf2))
	return 0;
	crc = crc_itu_t(crc, buf2 + off, len);
	}
	return crc;
	}

	static void udf_copy_fi_to_bufs(char buf1, int len1, char buf2, int len2,
	int off, struct fileIdentDesc *fi,
	uint8_t impuse, uint8_t name)
	{
	uint16_t crc;
	int fioff = off;
	int crcoff = off + sizeof(struct tag);
	unsigned int crclen = udf_dir_entry_len(fi) - sizeof(struct tag);
	char zeros[UDF_NAME_PAD] = {};
	int endoff = off + udf_dir_entry_len(fi);

	udf_copy_to_bufs(buf1, len1, buf2, len2, off, fi,
	sizeof(struct fileIdentDesc));
	off += sizeof(struct fileIdentDesc);
	if (impuse)
	udf_copy_to_bufs(buf1, len1, buf2, len2, off, impuse,
	le16_to_cpu(fi->lengthOfImpUse));
	off += le16_to_cpu(fi->lengthOfImpUse);
	if (name) {
	udf_copy_to_bufs(buf1, len1, buf2, len2, off, name,
	fi->lengthFileIdent);
	off += fi->lengthFileIdent;
	udf_copy_to_bufs(buf1, len1, buf2, len2, off, zeros,
	endoff - off);
	}

	crc = udf_crc_fi_bufs(buf1, len1, buf2, len2, crcoff, crclen);
	fi->descTag.descCRC = cpu_to_le16(crc);
	fi->descTag.descCRCLength = cpu_to_le16(crclen);
	fi->descTag.tagChecksum = udf_tag_checksum(&fi->descTag);

	udf_copy_to_bufs(buf1, len1, buf2, len2, fioff, fi, sizeof(struct tag));
	}

	void udf_fiiter_write_fi(struct udf_fileident_iter iter, uint8_t impuse)
	{
	struct udf_inode_info *iinfo = UDF_I(iter->dir);
	void buf1, buf2 = NULL;
	int len1, len2 = 0, off;
	int blksize = 1 << iter->dir->i_blkbits;

	off = iter->pos & (blksize - 1);
	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
	buf1 = iinfo->i_data + iinfo->i_lenEAttr;
	len1 = iter->dir->i_size;
	} else {
	buf1 = iter->bh[0]->b_data;
	len1 = blksize;
	if (iter->bh[1]) {
	buf2 = iter->bh[1]->b_data;
	len2 = blksize;
	}
	}

	udf_copy_fi_to_bufs(buf1, len1, buf2, len2, off, &iter->fi, impuse,
	iter->name == iter->namebuf ? iter->name : NULL);

	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
	mark_inode_dirty(iter->dir);
	} else {
	mark_buffer_dirty_inode(iter->bh[0], iter->dir);
	if (iter->bh[1])
	mark_buffer_dirty_inode(iter->bh[1], iter->dir);
	}
	inode_inc_iversion(iter->dir);
	}

	void udf_fiiter_update_elen(struct udf_fileident_iter *iter, uint32_t new_elen)
	{
	struct udf_inode_info *iinfo = UDF_I(iter->dir);
	int diff = new_elen - iter->elen;

	/* Skip update when we already went past the last extent */
	if (!iter->elen)
	return;
	iter->elen = new_elen;
	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
	iter->epos.offset -= sizeof(struct short_ad);
	else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
	iter->epos.offset -= sizeof(struct long_ad);
	udf_write_aext(iter->dir, &iter->epos, &iter->eloc, iter->elen, 1);
	iinfo->i_lenExtents += diff;
	mark_inode_dirty(iter->dir);
	}

	/* Append new block to directory. @iter is expected to point at EOF */
	int udf_fiiter_append_blk(struct udf_fileident_iter *iter)
	{
	struct udf_inode_info *iinfo = UDF_I(iter->dir);
	int blksize = 1 << iter->dir->i_blkbits;
	struct buffer_head *bh;
	sector_t block;
	uint32_t old_elen = iter->elen;
	int err;
	int8_t etype;

	if (WARN_ON_ONCE(iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB))
	return -EINVAL;

	/* Round up last extent in the file */
	udf_fiiter_update_elen(iter, ALIGN(iter->elen, blksize));

	/* Allocate new block and refresh mapping information */
	block = iinfo->i_lenExtents >> iter->dir->i_blkbits;
	bh = udf_bread(iter->dir, block, 1, &err);
	if (!bh) {
	udf_fiiter_update_elen(iter, old_elen);
	return err;
	}
	err = inode_bmap(iter->dir, block, &iter->epos, &iter->eloc, &iter->elen,
	&iter->loffset, &etype);
	if (err <= 0 \|\| etype != (EXT_RECORDED_ALLOCATED >> 30)) {
	udf_err(iter->dir->i_sb,
	"block %llu not allocated in directory (ino %lu)\n",
	(unsigned long long)block, iter->dir->i_ino);
	return -EFSCORRUPTED;
	}
	if (!(iter->pos & (blksize - 1))) {
	brelse(iter->bh[0]);
	iter->bh[0] = bh;
	} else {
	iter->bh[1] = bh;
	}
	return 0;
	}

	struct short_ad udf_get_fileshortad(uint8_t ptr, int maxoffset, uint32_t *offset,
	int inc)
	{
	struct short_ad *sa;

	if ((!ptr) \|\| (!offset)) {
	pr_err("%s: invalidparms\n", __func__);
	return NULL;
	}

	if ((*offset + sizeof(struct short_ad)) > maxoffset)
	return NULL;
	else {
	sa = (struct short_ad *)ptr;
	if (sa->extLength == 0)
	return NULL;
	}

	if (inc)
	*offset += sizeof(struct short_ad);
	return sa;
	}

	struct long_ad udf_get_filelongad(uint8_t ptr, int maxoffset, uint32_t *offset, int inc)
	{
	struct long_ad *la;

	if ((!ptr) \|\| (!offset)) {
	pr_err("%s: invalidparms\n", __func__);
	return NULL;
	}

	if ((*offset + sizeof(struct long_ad)) > maxoffset)
	return NULL;
	else {
	la = (struct long_ad *)ptr;
	if (la->extLength == 0)
	return NULL;
	}

	if (inc)
	*offset += sizeof(struct long_ad);
	return la;
	}