fs/quota/quota_tree.c - LeafOS-Devices/android_kernel_samsung_exynos9820 - Gitiles

 /*
  *	vfsv0 quota IO operations on file
  */

 #include <linux/errno.h>
 #include <linux/fs.h>
 #include <linux/mount.h>
 #include <linux/dqblk_v2.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/quotaops.h>

 #include <asm/byteorder.h>

 #include "quota_tree.h"

 MODULE_AUTHOR("Jan Kara");
 MODULE_DESCRIPTION("Quota trie support");
 MODULE_LICENSE("GPL");

 #define __QUOTA_QT_PARANOIA

 static int __get_index(struct qtree_mem_dqinfo *info, qid_t id, int depth)
 {
 	unsigned int epb = info->dqi_usable_bs >> 2;

 	depth = info->dqi_qtree_depth - depth - 1;
 	while (depth--)
 		id /= epb;
 	return id % epb;
 }

 static int get_index(struct qtree_mem_dqinfo *info, struct kqid qid, int depth)
 {
 	qid_t id = from_kqid(&init_user_ns, qid);

 	return __get_index(info, id, depth);
 }

 /* Number of entries in one blocks */
 static int qtree_dqstr_in_blk(struct qtree_mem_dqinfo *info)
 {
 	return (info->dqi_usable_bs - sizeof(struct qt_disk_dqdbheader))
 	       / info->dqi_entry_size;
 }

 static char *getdqbuf(size_t size)
 {
 	char *buf = kmalloc(size, GFP_NOFS);
 	if (!buf)
 		printk(KERN_WARNING
 		       "VFS: Not enough memory for quota buffers.\n");
 	return buf;
 }

 static ssize_t read_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)
 {
 	struct super_block *sb = info->dqi_sb;

 	memset(buf, 0, info->dqi_usable_bs);
 	return sb->s_op->quota_read(sb, info->dqi_type, buf,
 	       info->dqi_usable_bs, (loff_t)blk << info->dqi_blocksize_bits);
 }

 static ssize_t write_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf)
 {
 	struct super_block *sb = info->dqi_sb;
 	ssize_t ret;

 	ret = sb->s_op->quota_write(sb, info->dqi_type, buf,
 	       info->dqi_usable_bs, (loff_t)blk << info->dqi_blocksize_bits);
 	if (ret != info->dqi_usable_bs) {
 		quota_error(sb, "dquota write failed");
 		if (ret >= 0)
 			ret = -EIO;
 	}
 	return ret;
 }

 /* Remove empty block from list and return it */
 static int get_free_dqblk(struct qtree_mem_dqinfo *info)
 {
 	char *buf = getdqbuf(info->dqi_usable_bs);
 	struct qt_disk_dqdbheader *dh = (struct qt_disk_dqdbheader *)buf;
 	int ret, blk;

 	if (!buf)
 		return -ENOMEM;
 	if (info->dqi_free_blk) {
 		blk = info->dqi_free_blk;
 		ret = read_blk(info, blk, buf);
 		if (ret < 0)
 			goto out_buf;
 		info->dqi_free_blk = le32_to_cpu(dh->dqdh_next_free);
 	}
 	else {
 		memset(buf, 0, info->dqi_usable_bs);
 		/* Assure block allocation... */
 		ret = write_blk(info, info->dqi_blocks, buf);
 		if (ret < 0)
 			goto out_buf;
 		blk = info->dqi_blocks++;
 	}
 	mark_info_dirty(info->dqi_sb, info->dqi_type);
 	ret = blk;
 out_buf:
 	kfree(buf);
 	return ret;
 }

 /* Insert empty block to the list */
 static int put_free_dqblk(struct qtree_mem_dqinfo *info, char *buf, uint blk)
 {
 	struct qt_disk_dqdbheader *dh = (struct qt_disk_dqdbheader *)buf;
 	int err;

 	dh->dqdh_next_free = cpu_to_le32(info->dqi_free_blk);
 	dh->dqdh_prev_free = cpu_to_le32(0);
 	dh->dqdh_entries = cpu_to_le16(0);
 	err = write_blk(info, blk, buf);
 	if (err < 0)
 		return err;
 	info->dqi_free_blk = blk;
 	mark_info_dirty(info->dqi_sb, info->dqi_type);
 	return 0;
 }

 /* Remove given block from the list of blocks with free entries */
 static int remove_free_dqentry(struct qtree_mem_dqinfo *info, char *buf,
 			       uint blk)
 {
 	char *tmpbuf = getdqbuf(info->dqi_usable_bs);
 	struct qt_disk_dqdbheader *dh = (struct qt_disk_dqdbheader *)buf;
 	uint nextblk = le32_to_cpu(dh->dqdh_next_free);
 	uint prevblk = le32_to_cpu(dh->dqdh_prev_free);
 	int err;

 	if (!tmpbuf)
 		return -ENOMEM;
 	if (nextblk) {
 		err = read_blk(info, nextblk, tmpbuf);
 		if (err < 0)
 			goto out_buf;
 		((struct qt_disk_dqdbheader *)tmpbuf)->dqdh_prev_free =
 							dh->dqdh_prev_free;
 		err = write_blk(info, nextblk, tmpbuf);
 		if (err < 0)
 			goto out_buf;
 	}
 	if (prevblk) {
 		err = read_blk(info, prevblk, tmpbuf);
 		if (err < 0)
 			goto out_buf;
 		((struct qt_disk_dqdbheader *)tmpbuf)->dqdh_next_free =
 							dh->dqdh_next_free;
 		err = write_blk(info, prevblk, tmpbuf);
 		if (err < 0)
 			goto out_buf;
 	} else {
 		info->dqi_free_entry = nextblk;
 		mark_info_dirty(info->dqi_sb, info->dqi_type);
 	}
 	kfree(tmpbuf);
 	dh->dqdh_next_free = dh->dqdh_prev_free = cpu_to_le32(0);
 	/* No matter whether write succeeds block is out of list */
 	if (write_blk(info, blk, buf) < 0)
 		quota_error(info->dqi_sb, "Can't write block (%u) "
 			    "with free entries", blk);
 	return 0;
 out_buf:
 	kfree(tmpbuf);
 	return err;
 }

 /* Insert given block to the beginning of list with free entries */
 static int insert_free_dqentry(struct qtree_mem_dqinfo *info, char *buf,
 			       uint blk)
 {
 	char *tmpbuf = getdqbuf(info->dqi_usable_bs);
 	struct qt_disk_dqdbheader *dh = (struct qt_disk_dqdbheader *)buf;
 	int err;

 	if (!tmpbuf)
 		return -ENOMEM;
 	dh->dqdh_next_free = cpu_to_le32(info->dqi_free_entry);
 	dh->dqdh_prev_free = cpu_to_le32(0);
 	err = write_blk(info, blk, buf);
 	if (err < 0)
 		goto out_buf;
 	if (info->dqi_free_entry) {
 		err = read_blk(info, info->dqi_free_entry, tmpbuf);
 		if (err < 0)
 			goto out_buf;
 		((struct qt_disk_dqdbheader *)tmpbuf)->dqdh_prev_free =
 							cpu_to_le32(blk);
 		err = write_blk(info, info->dqi_free_entry, tmpbuf);
 		if (err < 0)
 			goto out_buf;
 	}
 	kfree(tmpbuf);
 	info->dqi_free_entry = blk;
 	mark_info_dirty(info->dqi_sb, info->dqi_type);
 	return 0;
 out_buf:
 	kfree(tmpbuf);
 	return err;
 }

 /* Is the entry in the block free? */
 int qtree_entry_unused(struct qtree_mem_dqinfo *info, char *disk)
 {
 	int i;

 	for (i = 0; i < info->dqi_entry_size; i++)
 		if (disk[i])
 			return 0;
 	return 1;
 }
 EXPORT_SYMBOL(qtree_entry_unused);

 /* Find space for dquot */
 static uint find_free_dqentry(struct qtree_mem_dqinfo *info,
 			      struct dquot *dquot, int *err)
 {
 	uint blk, i;
 	struct qt_disk_dqdbheader *dh;
 	char *buf = getdqbuf(info->dqi_usable_bs);
 	char *ddquot;

 	*err = 0;
 	if (!buf) {
 		*err = -ENOMEM;
 		return 0;
 	}
 	dh = (struct qt_disk_dqdbheader *)buf;
 	if (info->dqi_free_entry) {
 		blk = info->dqi_free_entry;
 		*err = read_blk(info, blk, buf);
 		if (*err < 0)
 			goto out_buf;
 	} else {
 		blk = get_free_dqblk(info);
 		if ((int)blk < 0) {
 			*err = blk;
 			kfree(buf);
 			return 0;
 		}
 		memset(buf, 0, info->dqi_usable_bs);
 		/* This is enough as the block is already zeroed and the entry
 		 * list is empty... */
 		info->dqi_free_entry = blk;
 		mark_info_dirty(dquot->dq_sb, dquot->dq_id.type);
 	}
 	/* Block will be full? */
 	if (le16_to_cpu(dh->dqdh_entries) + 1 >= qtree_dqstr_in_blk(info)) {
 		*err = remove_free_dqentry(info, buf, blk);
 		if (*err < 0) {
 			quota_error(dquot->dq_sb, "Can't remove block (%u) "
 				    "from entry free list", blk);
 			goto out_buf;
 		}
 	}
 	le16_add_cpu(&dh->dqdh_entries, 1);
 	/* Find free structure in block */
 	ddquot = buf + sizeof(struct qt_disk_dqdbheader);
 	for (i = 0; i < qtree_dqstr_in_blk(info); i++) {
 		if (qtree_entry_unused(info, ddquot))
 			break;
 		ddquot += info->dqi_entry_size;
 	}
 #ifdef __QUOTA_QT_PARANOIA
 	if (i == qtree_dqstr_in_blk(info)) {
 		quota_error(dquot->dq_sb, "Data block full but it shouldn't");
 		*err = -EIO;
 		goto out_buf;
 	}
 #endif
 	*err = write_blk(info, blk, buf);
 	if (*err < 0) {
 		quota_error(dquot->dq_sb, "Can't write quota data block %u",
 			    blk);
 		goto out_buf;
 	}
 	dquot->dq_off = ((loff_t)blk << info->dqi_blocksize_bits) +
 			sizeof(struct qt_disk_dqdbheader) +
 			i * info->dqi_entry_size;
 	kfree(buf);
 	return blk;
 out_buf:
 	kfree(buf);
 	return 0;
 }

 /* Insert reference to structure into the trie */
 static int do_insert_tree(struct qtree_mem_dqinfo *info, struct dquot *dquot,
 			  uint *treeblk, int depth)
 {
 	char *buf = getdqbuf(info->dqi_usable_bs);
 	int ret = 0, newson = 0, newact = 0;
 	__le32 *ref;
 	uint newblk;

 	if (!buf)
 		return -ENOMEM;
 	if (!*treeblk) {
 		ret = get_free_dqblk(info);
 		if (ret < 0)
 			goto out_buf;
 		*treeblk = ret;
 		memset(buf, 0, info->dqi_usable_bs);
 		newact = 1;
 	} else {
 		ret = read_blk(info, *treeblk, buf);
 		if (ret < 0) {
 			quota_error(dquot->dq_sb, "Can't read tree quota "
 				    "block %u", *treeblk);
 			goto out_buf;
 		}
 	}
 	ref = (__le32 *)buf;
 	newblk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
 	if (!newblk)
 		newson = 1;
 	if (depth == info->dqi_qtree_depth - 1) {
 #ifdef __QUOTA_QT_PARANOIA
 		if (newblk) {
 			quota_error(dquot->dq_sb, "Inserting already present "
 				    "quota entry (block %u)",
 				    le32_to_cpu(ref[get_index(info,
 						dquot->dq_id, depth)]));
 			ret = -EIO;
 			goto out_buf;
 		}
 #endif
 		newblk = find_free_dqentry(info, dquot, &ret);
 	} else {
 		ret = do_insert_tree(info, dquot, &newblk, depth+1);
 	}
 	if (newson && ret >= 0) {
 		ref[get_index(info, dquot->dq_id, depth)] =
 							cpu_to_le32(newblk);
 		ret = write_blk(info, *treeblk, buf);
 	} else if (newact && ret < 0) {
 		put_free_dqblk(info, buf, *treeblk);
 	}
 out_buf:
 	kfree(buf);
 	return ret;
 }

 /* Wrapper for inserting quota structure into tree */
 static inline int dq_insert_tree(struct qtree_mem_dqinfo *info,
 				 struct dquot *dquot)
 {
 	int tmp = QT_TREEOFF;

 #ifdef __QUOTA_QT_PARANOIA
 	if (info->dqi_blocks <= QT_TREEOFF) {
 		quota_error(dquot->dq_sb, "Quota tree root isn't allocated!");
 		return -EIO;
 	}
 #endif
 	return do_insert_tree(info, dquot, &tmp, 0);
 }

 /*
  * We don't have to be afraid of deadlocks as we never have quotas on quota
  * files...
  */
 int qtree_write_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot)
 {
 	int type = dquot->dq_id.type;
 	struct super_block *sb = dquot->dq_sb;
 	ssize_t ret;
 	char *ddquot = getdqbuf(info->dqi_entry_size);

 	if (!ddquot)
 		return -ENOMEM;

 	/* dq_off is guarded by dqio_sem */
 	if (!dquot->dq_off) {
 		ret = dq_insert_tree(info, dquot);
 		if (ret < 0) {
 			quota_error(sb, "Error %zd occurred while creating "
 				    "quota", ret);
 			kfree(ddquot);
 			return ret;
 		}
 	}
 	spin_lock(&dquot->dq_dqb_lock);
 	info->dqi_ops->mem2disk_dqblk(ddquot, dquot);
 	spin_unlock(&dquot->dq_dqb_lock);
 	ret = sb->s_op->quota_write(sb, type, ddquot, info->dqi_entry_size,
 				    dquot->dq_off);
 	if (ret != info->dqi_entry_size) {
 		quota_error(sb, "dquota write failed");
 		if (ret >= 0)
 			ret = -ENOSPC;
 	} else {
 		ret = 0;
 	}
 	dqstats_inc(DQST_WRITES);
 	kfree(ddquot);

 	return ret;
 }
 EXPORT_SYMBOL(qtree_write_dquot);

 /* Free dquot entry in data block */
 static int free_dqentry(struct qtree_mem_dqinfo *info, struct dquot *dquot,
 			uint blk)
 {
 	struct qt_disk_dqdbheader *dh;
 	char *buf = getdqbuf(info->dqi_usable_bs);
 	int ret = 0;

 	if (!buf)
 		return -ENOMEM;
 	if (dquot->dq_off >> info->dqi_blocksize_bits != blk) {
 		quota_error(dquot->dq_sb, "Quota structure has offset to "
 			"other block (%u) than it should (%u)", blk,
 			(uint)(dquot->dq_off >> info->dqi_blocksize_bits));
 		ret = -EIO;
 		goto out_buf;
 	}
 	ret = read_blk(info, blk, buf);
 	if (ret < 0) {
 		quota_error(dquot->dq_sb, "Can't read quota data block %u",
 			    blk);
 		goto out_buf;
 	}
 	dh = (struct qt_disk_dqdbheader *)buf;
 	le16_add_cpu(&dh->dqdh_entries, -1);
 	if (!le16_to_cpu(dh->dqdh_entries)) {	/* Block got free? */
 		ret = remove_free_dqentry(info, buf, blk);
 		if (ret >= 0)
 			ret = put_free_dqblk(info, buf, blk);
 		if (ret < 0) {
 			quota_error(dquot->dq_sb, "Can't move quota data block "
 				    "(%u) to free list", blk);
 			goto out_buf;
 		}
 	} else {
 		memset(buf +
 		       (dquot->dq_off & ((1 << info->dqi_blocksize_bits) - 1)),
 		       0, info->dqi_entry_size);
 		if (le16_to_cpu(dh->dqdh_entries) ==
 		    qtree_dqstr_in_blk(info) - 1) {
 			/* Insert will write block itself */
 			ret = insert_free_dqentry(info, buf, blk);
 			if (ret < 0) {
 				quota_error(dquot->dq_sb, "Can't insert quota "
 				    "data block (%u) to free entry list", blk);
 				goto out_buf;
 			}
 		} else {
 			ret = write_blk(info, blk, buf);
 			if (ret < 0) {
 				quota_error(dquot->dq_sb, "Can't write quota "
 					    "data block %u", blk);
 				goto out_buf;
 			}
 		}
 	}
 	dquot->dq_off = 0;	/* Quota is now unattached */
 out_buf:
 	kfree(buf);
 	return ret;
 }

 /* Remove reference to dquot from tree */
 static int remove_tree(struct qtree_mem_dqinfo *info, struct dquot *dquot,
 		       uint *blk, int depth)
 {
 	char *buf = getdqbuf(info->dqi_usable_bs);
 	int ret = 0;
 	uint newblk;
 	__le32 *ref = (__le32 *)buf;

 	if (!buf)
 		return -ENOMEM;
 	ret = read_blk(info, *blk, buf);
 	if (ret < 0) {
 		quota_error(dquot->dq_sb, "Can't read quota data block %u",
 			    *blk);
 		goto out_buf;
 	}
 	newblk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
 	if (newblk < QT_TREEOFF || newblk >= info->dqi_blocks) {
 		quota_error(dquot->dq_sb, "Getting block too big (%u >= %u)",
 			    newblk, info->dqi_blocks);
 		ret = -EUCLEAN;
 		goto out_buf;
 	}

 	if (depth == info->dqi_qtree_depth - 1) {
 		ret = free_dqentry(info, dquot, newblk);
 		newblk = 0;
 	} else {
 		ret = remove_tree(info, dquot, &newblk, depth+1);
 	}
 	if (ret >= 0 && !newblk) {
 		int i;
 		ref[get_index(info, dquot->dq_id, depth)] = cpu_to_le32(0);
 		/* Block got empty? */
 		for (i = 0; i < (info->dqi_usable_bs >> 2) && !ref[i]; i++)
 			;
 		/* Don't put the root block into the free block list */
 		if (i == (info->dqi_usable_bs >> 2)
 		    && *blk != QT_TREEOFF) {
 			put_free_dqblk(info, buf, *blk);
 			*blk = 0;
 		} else {
 			ret = write_blk(info, *blk, buf);
 			if (ret < 0)
 				quota_error(dquot->dq_sb,
 					    "Can't write quota tree block %u",
 					    *blk);
 		}
 	}
 out_buf:
 	kfree(buf);
 	return ret;
 }

 /* Delete dquot from tree */
 int qtree_delete_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot)
 {
 	uint tmp = QT_TREEOFF;

 	if (!dquot->dq_off)	/* Even not allocated? */
 		return 0;
 	return remove_tree(info, dquot, &tmp, 0);
 }
 EXPORT_SYMBOL(qtree_delete_dquot);

 /* Find entry in block */
 static loff_t find_block_dqentry(struct qtree_mem_dqinfo *info,
 				 struct dquot *dquot, uint blk)
 {
 	char *buf = getdqbuf(info->dqi_usable_bs);
 	loff_t ret = 0;
 	int i;
 	char *ddquot;

 	if (!buf)
 		return -ENOMEM;
 	ret = read_blk(info, blk, buf);
 	if (ret < 0) {
 		quota_error(dquot->dq_sb, "Can't read quota tree "
 			    "block %u", blk);
 		goto out_buf;
 	}
 	ddquot = buf + sizeof(struct qt_disk_dqdbheader);
 	for (i = 0; i < qtree_dqstr_in_blk(info); i++) {
 		if (info->dqi_ops->is_id(ddquot, dquot))
 			break;
 		ddquot += info->dqi_entry_size;
 	}
 	if (i == qtree_dqstr_in_blk(info)) {
 		quota_error(dquot->dq_sb,
 			    "Quota for id %u referenced but not present",
 			    from_kqid(&init_user_ns, dquot->dq_id));
 		ret = -EIO;
 		goto out_buf;
 	} else {
 		ret = ((loff_t)blk << info->dqi_blocksize_bits) + sizeof(struct
 		  qt_disk_dqdbheader) + i * info->dqi_entry_size;
 	}
 out_buf:
 	kfree(buf);
 	return ret;
 }

 /* Find entry for given id in the tree */
 static loff_t find_tree_dqentry(struct qtree_mem_dqinfo *info,
 				struct dquot *dquot, uint blk, int depth)
 {
 	char *buf = getdqbuf(info->dqi_usable_bs);
 	loff_t ret = 0;
 	__le32 *ref = (__le32 *)buf;

 	if (!buf)
 		return -ENOMEM;
 	ret = read_blk(info, blk, buf);
 	if (ret < 0) {
 		quota_error(dquot->dq_sb, "Can't read quota tree block %u",
 			    blk);
 		goto out_buf;
 	}
 	ret = 0;
 	blk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
 	if (!blk)	/* No reference? */
 		goto out_buf;
 	if (blk < QT_TREEOFF || blk >= info->dqi_blocks) {
 		quota_error(dquot->dq_sb, "Getting block too big (%u >= %u)",
 			    blk, info->dqi_blocks);
 		ret = -EUCLEAN;
 		goto out_buf;
 	}

 	if (depth < info->dqi_qtree_depth - 1)
 		ret = find_tree_dqentry(info, dquot, blk, depth+1);
 	else
 		ret = find_block_dqentry(info, dquot, blk);
 out_buf:
 	kfree(buf);
 	return ret;
 }

 /* Find entry for given id in the tree - wrapper function */
 static inline loff_t find_dqentry(struct qtree_mem_dqinfo *info,
 				  struct dquot *dquot)
 {
 	return find_tree_dqentry(info, dquot, QT_TREEOFF, 0);
 }

 int qtree_read_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot)
 {
 	int type = dquot->dq_id.type;
 	struct super_block *sb = dquot->dq_sb;
 	loff_t offset;
 	char *ddquot;
 	int ret = 0;

 #ifdef __QUOTA_QT_PARANOIA
 	/* Invalidated quota? */
 	if (!sb_dqopt(dquot->dq_sb)->files[type]) {
 		quota_error(sb, "Quota invalidated while reading!");
 		return -EIO;
 	}
 #endif
 	/* Do we know offset of the dquot entry in the quota file? */
 	if (!dquot->dq_off) {
 		offset = find_dqentry(info, dquot);
 		if (offset <= 0) {	/* Entry not present? */
 			if (offset < 0)
 				quota_error(sb,"Can't read quota structure "
 					    "for id %u",
 					    from_kqid(&init_user_ns,
 						      dquot->dq_id));
 			dquot->dq_off = 0;
 			set_bit(DQ_FAKE_B, &dquot->dq_flags);
 			memset(&dquot->dq_dqb, 0, sizeof(struct mem_dqblk));
 			ret = offset;
 			goto out;
 		}
 		dquot->dq_off = offset;
 	}
 	ddquot = getdqbuf(info->dqi_entry_size);
 	if (!ddquot)
 		return -ENOMEM;
 	ret = sb->s_op->quota_read(sb, type, ddquot, info->dqi_entry_size,
 				   dquot->dq_off);
 	if (ret != info->dqi_entry_size) {
 		if (ret >= 0)
 			ret = -EIO;
 		quota_error(sb, "Error while reading quota structure for id %u",
 			    from_kqid(&init_user_ns, dquot->dq_id));
 		set_bit(DQ_FAKE_B, &dquot->dq_flags);
 		memset(&dquot->dq_dqb, 0, sizeof(struct mem_dqblk));
 		kfree(ddquot);
 		goto out;
 	}
 	spin_lock(&dquot->dq_dqb_lock);
 	info->dqi_ops->disk2mem_dqblk(dquot, ddquot);
 	if (!dquot->dq_dqb.dqb_bhardlimit &&
 	    !dquot->dq_dqb.dqb_bsoftlimit &&
 	    !dquot->dq_dqb.dqb_ihardlimit &&
 	    !dquot->dq_dqb.dqb_isoftlimit)
 		set_bit(DQ_FAKE_B, &dquot->dq_flags);
 	spin_unlock(&dquot->dq_dqb_lock);
 	kfree(ddquot);
 out:
 	dqstats_inc(DQST_READS);
 	return ret;
 }
 EXPORT_SYMBOL(qtree_read_dquot);

 /* Check whether dquot should not be deleted. We know we are
  * the only one operating on dquot (thanks to dq_lock) */
 int qtree_release_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot)
 {
 	if (test_bit(DQ_FAKE_B, &dquot->dq_flags) &&
 	    !(dquot->dq_dqb.dqb_curinodes | dquot->dq_dqb.dqb_curspace))
 		return qtree_delete_dquot(info, dquot);
 	return 0;
 }
 EXPORT_SYMBOL(qtree_release_dquot);

 static int find_next_id(struct qtree_mem_dqinfo *info, qid_t *id,
 			unsigned int blk, int depth)
 {
 	char *buf = getdqbuf(info->dqi_usable_bs);
 	__le32 *ref = (__le32 *)buf;
 	ssize_t ret;
 	unsigned int epb = info->dqi_usable_bs >> 2;
 	unsigned int level_inc = 1;
 	int i;

 	if (!buf)
 		return -ENOMEM;

 	for (i = depth; i < info->dqi_qtree_depth - 1; i++)
 		level_inc *= epb;

 	ret = read_blk(info, blk, buf);
 	if (ret < 0) {
 		quota_error(info->dqi_sb,
 			    "Can't read quota tree block %u", blk);
 		goto out_buf;
 	}
 	for (i = __get_index(info, *id, depth); i < epb; i++) {
 		if (ref[i] == cpu_to_le32(0)) {
 			*id += level_inc;
 			continue;
 		}
 		if (depth == info->dqi_qtree_depth - 1) {
 			ret = 0;
 			goto out_buf;
 		}
 		ret = find_next_id(info, id, le32_to_cpu(ref[i]), depth + 1);
 		if (ret != -ENOENT)
 			break;
 	}
 	if (i == epb) {
 		ret = -ENOENT;
 		goto out_buf;
 	}
 out_buf:
 	kfree(buf);
 	return ret;
 }

 int qtree_get_next_id(struct qtree_mem_dqinfo *info, struct kqid *qid)
 {
 	qid_t id = from_kqid(&init_user_ns, *qid);
 	int ret;

 	ret = find_next_id(info, &id, QT_TREEOFF, 0);
 	if (ret < 0)
 		return ret;
 	*qid = make_kqid(&init_user_ns, qid->type, id);
 	return 0;
 }
 EXPORT_SYMBOL(qtree_get_next_id);
	/*
	* vfsv0 quota IO operations on file
	*/

	#include <linux/errno.h>
	#include <linux/fs.h>
	#include <linux/mount.h>
	#include <linux/dqblk_v2.h>
	#include <linux/kernel.h>
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/quotaops.h>

	#include <asm/byteorder.h>

	#include "quota_tree.h"

	MODULE_AUTHOR("Jan Kara");
	MODULE_DESCRIPTION("Quota trie support");
	MODULE_LICENSE("GPL");

	#define __QUOTA_QT_PARANOIA

	static int __get_index(struct qtree_mem_dqinfo *info, qid_t id, int depth)
	{
	unsigned int epb = info->dqi_usable_bs >> 2;

	depth = info->dqi_qtree_depth - depth - 1;
	while (depth--)
	id /= epb;
	return id % epb;
	}

	static int get_index(struct qtree_mem_dqinfo *info, struct kqid qid, int depth)
	{
	qid_t id = from_kqid(&init_user_ns, qid);

	return __get_index(info, id, depth);
	}

	/* Number of entries in one blocks */
	static int qtree_dqstr_in_blk(struct qtree_mem_dqinfo *info)
	{
	return (info->dqi_usable_bs - sizeof(struct qt_disk_dqdbheader))
	/ info->dqi_entry_size;
	}

	static char *getdqbuf(size_t size)
	{
	char *buf = kmalloc(size, GFP_NOFS);
	if (!buf)
	printk(KERN_WARNING
	"VFS: Not enough memory for quota buffers.\n");
	return buf;
	}

	static ssize_t read_blk(struct qtree_mem_dqinfo info, uint blk, char buf)
	{
	struct super_block *sb = info->dqi_sb;

	memset(buf, 0, info->dqi_usable_bs);
	return sb->s_op->quota_read(sb, info->dqi_type, buf,
	info->dqi_usable_bs, (loff_t)blk << info->dqi_blocksize_bits);
	}

	static ssize_t write_blk(struct qtree_mem_dqinfo info, uint blk, char buf)
	{
	struct super_block *sb = info->dqi_sb;
	ssize_t ret;

	ret = sb->s_op->quota_write(sb, info->dqi_type, buf,
	info->dqi_usable_bs, (loff_t)blk << info->dqi_blocksize_bits);
	if (ret != info->dqi_usable_bs) {
	quota_error(sb, "dquota write failed");
	if (ret >= 0)
	ret = -EIO;
	}
	return ret;
	}

	/* Remove empty block from list and return it */
	static int get_free_dqblk(struct qtree_mem_dqinfo *info)
	{
	char *buf = getdqbuf(info->dqi_usable_bs);
	struct qt_disk_dqdbheader dh = (struct qt_disk_dqdbheader )buf;
	int ret, blk;

	if (!buf)
	return -ENOMEM;
	if (info->dqi_free_blk) {
	blk = info->dqi_free_blk;
	ret = read_blk(info, blk, buf);
	if (ret < 0)
	goto out_buf;
	info->dqi_free_blk = le32_to_cpu(dh->dqdh_next_free);
	}
	else {
	memset(buf, 0, info->dqi_usable_bs);
	/* Assure block allocation... */
	ret = write_blk(info, info->dqi_blocks, buf);
	if (ret < 0)
	goto out_buf;
	blk = info->dqi_blocks++;
	}
	mark_info_dirty(info->dqi_sb, info->dqi_type);
	ret = blk;
	out_buf:
	kfree(buf);
	return ret;
	}

	/* Insert empty block to the list */
	static int put_free_dqblk(struct qtree_mem_dqinfo info, char buf, uint blk)
	{
	struct qt_disk_dqdbheader dh = (struct qt_disk_dqdbheader )buf;
	int err;

	dh->dqdh_next_free = cpu_to_le32(info->dqi_free_blk);
	dh->dqdh_prev_free = cpu_to_le32(0);
	dh->dqdh_entries = cpu_to_le16(0);
	err = write_blk(info, blk, buf);
	if (err < 0)
	return err;
	info->dqi_free_blk = blk;
	mark_info_dirty(info->dqi_sb, info->dqi_type);
	return 0;
	}

	/* Remove given block from the list of blocks with free entries */
	static int remove_free_dqentry(struct qtree_mem_dqinfo info, char buf,
	uint blk)
	{
	char *tmpbuf = getdqbuf(info->dqi_usable_bs);
	struct qt_disk_dqdbheader dh = (struct qt_disk_dqdbheader )buf;
	uint nextblk = le32_to_cpu(dh->dqdh_next_free);
	uint prevblk = le32_to_cpu(dh->dqdh_prev_free);
	int err;

	if (!tmpbuf)
	return -ENOMEM;
	if (nextblk) {
	err = read_blk(info, nextblk, tmpbuf);
	if (err < 0)
	goto out_buf;
	((struct qt_disk_dqdbheader *)tmpbuf)->dqdh_prev_free =
	dh->dqdh_prev_free;
	err = write_blk(info, nextblk, tmpbuf);
	if (err < 0)
	goto out_buf;
	}
	if (prevblk) {
	err = read_blk(info, prevblk, tmpbuf);
	if (err < 0)
	goto out_buf;
	((struct qt_disk_dqdbheader *)tmpbuf)->dqdh_next_free =
	dh->dqdh_next_free;
	err = write_blk(info, prevblk, tmpbuf);
	if (err < 0)
	goto out_buf;
	} else {
	info->dqi_free_entry = nextblk;
	mark_info_dirty(info->dqi_sb, info->dqi_type);
	}
	kfree(tmpbuf);
	dh->dqdh_next_free = dh->dqdh_prev_free = cpu_to_le32(0);
	/* No matter whether write succeeds block is out of list */
	if (write_blk(info, blk, buf) < 0)
	quota_error(info->dqi_sb, "Can't write block (%u) "
	"with free entries", blk);
	return 0;
	out_buf:
	kfree(tmpbuf);
	return err;
	}

	/* Insert given block to the beginning of list with free entries */
	static int insert_free_dqentry(struct qtree_mem_dqinfo info, char buf,
	uint blk)
	{
	char *tmpbuf = getdqbuf(info->dqi_usable_bs);
	struct qt_disk_dqdbheader dh = (struct qt_disk_dqdbheader )buf;
	int err;

	if (!tmpbuf)
	return -ENOMEM;
	dh->dqdh_next_free = cpu_to_le32(info->dqi_free_entry);
	dh->dqdh_prev_free = cpu_to_le32(0);
	err = write_blk(info, blk, buf);
	if (err < 0)
	goto out_buf;
	if (info->dqi_free_entry) {
	err = read_blk(info, info->dqi_free_entry, tmpbuf);
	if (err < 0)
	goto out_buf;
	((struct qt_disk_dqdbheader *)tmpbuf)->dqdh_prev_free =
	cpu_to_le32(blk);
	err = write_blk(info, info->dqi_free_entry, tmpbuf);
	if (err < 0)
	goto out_buf;
	}
	kfree(tmpbuf);
	info->dqi_free_entry = blk;
	mark_info_dirty(info->dqi_sb, info->dqi_type);
	return 0;
	out_buf:
	kfree(tmpbuf);
	return err;
	}

	/* Is the entry in the block free? */
	int qtree_entry_unused(struct qtree_mem_dqinfo info, char disk)
	{
	int i;

	for (i = 0; i < info->dqi_entry_size; i++)
	if (disk[i])
	return 0;
	return 1;
	}
	EXPORT_SYMBOL(qtree_entry_unused);

	/* Find space for dquot */
	static uint find_free_dqentry(struct qtree_mem_dqinfo *info,
	struct dquot dquot, int err)
	{
	uint blk, i;
	struct qt_disk_dqdbheader *dh;
	char *buf = getdqbuf(info->dqi_usable_bs);
	char *ddquot;

	*err = 0;
	if (!buf) {
	*err = -ENOMEM;
	return 0;
	}
	dh = (struct qt_disk_dqdbheader *)buf;
	if (info->dqi_free_entry) {
	blk = info->dqi_free_entry;
	*err = read_blk(info, blk, buf);
	if (*err < 0)
	goto out_buf;
	} else {
	blk = get_free_dqblk(info);
	if ((int)blk < 0) {
	*err = blk;
	kfree(buf);
	return 0;
	}
	memset(buf, 0, info->dqi_usable_bs);
	/* This is enough as the block is already zeroed and the entry
	* list is empty... */
	info->dqi_free_entry = blk;
	mark_info_dirty(dquot->dq_sb, dquot->dq_id.type);
	}
	/* Block will be full? */
	if (le16_to_cpu(dh->dqdh_entries) + 1 >= qtree_dqstr_in_blk(info)) {
	*err = remove_free_dqentry(info, buf, blk);
	if (*err < 0) {
	quota_error(dquot->dq_sb, "Can't remove block (%u) "
	"from entry free list", blk);
	goto out_buf;
	}
	}
	le16_add_cpu(&dh->dqdh_entries, 1);
	/* Find free structure in block */
	ddquot = buf + sizeof(struct qt_disk_dqdbheader);
	for (i = 0; i < qtree_dqstr_in_blk(info); i++) {
	if (qtree_entry_unused(info, ddquot))
	break;
	ddquot += info->dqi_entry_size;
	}
	#ifdef __QUOTA_QT_PARANOIA
	if (i == qtree_dqstr_in_blk(info)) {
	quota_error(dquot->dq_sb, "Data block full but it shouldn't");
	*err = -EIO;
	goto out_buf;
	}
	#endif
	*err = write_blk(info, blk, buf);
	if (*err < 0) {
	quota_error(dquot->dq_sb, "Can't write quota data block %u",
	blk);
	goto out_buf;
	}
	dquot->dq_off = ((loff_t)blk << info->dqi_blocksize_bits) +
	sizeof(struct qt_disk_dqdbheader) +
	i * info->dqi_entry_size;
	kfree(buf);
	return blk;
	out_buf:
	kfree(buf);
	return 0;
	}

	/* Insert reference to structure into the trie */
	static int do_insert_tree(struct qtree_mem_dqinfo info, struct dquot dquot,
	uint *treeblk, int depth)
	{
	char *buf = getdqbuf(info->dqi_usable_bs);
	int ret = 0, newson = 0, newact = 0;
	__le32 *ref;
	uint newblk;

	if (!buf)
	return -ENOMEM;
	if (!*treeblk) {
	ret = get_free_dqblk(info);
	if (ret < 0)
	goto out_buf;
	*treeblk = ret;
	memset(buf, 0, info->dqi_usable_bs);
	newact = 1;
	} else {
	ret = read_blk(info, *treeblk, buf);
	if (ret < 0) {
	quota_error(dquot->dq_sb, "Can't read tree quota "
	"block %u", *treeblk);
	goto out_buf;
	}
	}
	ref = (__le32 *)buf;
	newblk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
	if (!newblk)
	newson = 1;
	if (depth == info->dqi_qtree_depth - 1) {
	#ifdef __QUOTA_QT_PARANOIA
	if (newblk) {
	quota_error(dquot->dq_sb, "Inserting already present "
	"quota entry (block %u)",
	le32_to_cpu(ref[get_index(info,
	dquot->dq_id, depth)]));
	ret = -EIO;
	goto out_buf;
	}
	#endif
	newblk = find_free_dqentry(info, dquot, &ret);
	} else {
	ret = do_insert_tree(info, dquot, &newblk, depth+1);
	}
	if (newson && ret >= 0) {
	ref[get_index(info, dquot->dq_id, depth)] =
	cpu_to_le32(newblk);
	ret = write_blk(info, *treeblk, buf);
	} else if (newact && ret < 0) {
	put_free_dqblk(info, buf, *treeblk);
	}
	out_buf:
	kfree(buf);
	return ret;
	}

	/* Wrapper for inserting quota structure into tree */
	static inline int dq_insert_tree(struct qtree_mem_dqinfo *info,
	struct dquot *dquot)
	{
	int tmp = QT_TREEOFF;

	#ifdef __QUOTA_QT_PARANOIA
	if (info->dqi_blocks <= QT_TREEOFF) {
	quota_error(dquot->dq_sb, "Quota tree root isn't allocated!");
	return -EIO;
	}
	#endif
	return do_insert_tree(info, dquot, &tmp, 0);
	}

	/*
	* We don't have to be afraid of deadlocks as we never have quotas on quota
	* files...
	*/
	int qtree_write_dquot(struct qtree_mem_dqinfo info, struct dquot dquot)
	{
	int type = dquot->dq_id.type;
	struct super_block *sb = dquot->dq_sb;
	ssize_t ret;
	char *ddquot = getdqbuf(info->dqi_entry_size);

	if (!ddquot)
	return -ENOMEM;

	/* dq_off is guarded by dqio_sem */
	if (!dquot->dq_off) {
	ret = dq_insert_tree(info, dquot);
	if (ret < 0) {
	quota_error(sb, "Error %zd occurred while creating "
	"quota", ret);
	kfree(ddquot);
	return ret;
	}
	}
	spin_lock(&dquot->dq_dqb_lock);
	info->dqi_ops->mem2disk_dqblk(ddquot, dquot);
	spin_unlock(&dquot->dq_dqb_lock);
	ret = sb->s_op->quota_write(sb, type, ddquot, info->dqi_entry_size,
	dquot->dq_off);
	if (ret != info->dqi_entry_size) {
	quota_error(sb, "dquota write failed");
	if (ret >= 0)
	ret = -ENOSPC;
	} else {
	ret = 0;
	}
	dqstats_inc(DQST_WRITES);
	kfree(ddquot);

	return ret;
	}
	EXPORT_SYMBOL(qtree_write_dquot);

	/* Free dquot entry in data block */
	static int free_dqentry(struct qtree_mem_dqinfo info, struct dquot dquot,
	uint blk)
	{
	struct qt_disk_dqdbheader *dh;
	char *buf = getdqbuf(info->dqi_usable_bs);
	int ret = 0;

	if (!buf)
	return -ENOMEM;
	if (dquot->dq_off >> info->dqi_blocksize_bits != blk) {
	quota_error(dquot->dq_sb, "Quota structure has offset to "
	"other block (%u) than it should (%u)", blk,
	(uint)(dquot->dq_off >> info->dqi_blocksize_bits));
	ret = -EIO;
	goto out_buf;
	}
	ret = read_blk(info, blk, buf);
	if (ret < 0) {
	quota_error(dquot->dq_sb, "Can't read quota data block %u",
	blk);
	goto out_buf;
	}
	dh = (struct qt_disk_dqdbheader *)buf;
	le16_add_cpu(&dh->dqdh_entries, -1);
	if (!le16_to_cpu(dh->dqdh_entries)) { /* Block got free? */
	ret = remove_free_dqentry(info, buf, blk);
	if (ret >= 0)
	ret = put_free_dqblk(info, buf, blk);
	if (ret < 0) {
	quota_error(dquot->dq_sb, "Can't move quota data block "
	"(%u) to free list", blk);
	goto out_buf;
	}
	} else {
	memset(buf +
	(dquot->dq_off & ((1 << info->dqi_blocksize_bits) - 1)),
	0, info->dqi_entry_size);
	if (le16_to_cpu(dh->dqdh_entries) ==
	qtree_dqstr_in_blk(info) - 1) {
	/* Insert will write block itself */
	ret = insert_free_dqentry(info, buf, blk);
	if (ret < 0) {
	quota_error(dquot->dq_sb, "Can't insert quota "
	"data block (%u) to free entry list", blk);
	goto out_buf;
	}
	} else {
	ret = write_blk(info, blk, buf);
	if (ret < 0) {
	quota_error(dquot->dq_sb, "Can't write quota "
	"data block %u", blk);
	goto out_buf;
	}
	}
	}
	dquot->dq_off = 0; /* Quota is now unattached */
	out_buf:
	kfree(buf);
	return ret;
	}

	/* Remove reference to dquot from tree */
	static int remove_tree(struct qtree_mem_dqinfo info, struct dquot dquot,
	uint *blk, int depth)
	{
	char *buf = getdqbuf(info->dqi_usable_bs);
	int ret = 0;
	uint newblk;
	__le32 ref = (__le32 )buf;

	if (!buf)
	return -ENOMEM;
	ret = read_blk(info, *blk, buf);
	if (ret < 0) {
	quota_error(dquot->dq_sb, "Can't read quota data block %u",
	*blk);
	goto out_buf;
	}
	newblk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
	if (newblk < QT_TREEOFF \|\| newblk >= info->dqi_blocks) {
	quota_error(dquot->dq_sb, "Getting block too big (%u >= %u)",
	newblk, info->dqi_blocks);
	ret = -EUCLEAN;
	goto out_buf;
	}

	if (depth == info->dqi_qtree_depth - 1) {
	ret = free_dqentry(info, dquot, newblk);
	newblk = 0;
	} else {
	ret = remove_tree(info, dquot, &newblk, depth+1);
	}
	if (ret >= 0 && !newblk) {
	int i;
	ref[get_index(info, dquot->dq_id, depth)] = cpu_to_le32(0);
	/* Block got empty? */
	for (i = 0; i < (info->dqi_usable_bs >> 2) && !ref[i]; i++)
	;
	/* Don't put the root block into the free block list */
	if (i == (info->dqi_usable_bs >> 2)
	&& *blk != QT_TREEOFF) {
	put_free_dqblk(info, buf, *blk);
	*blk = 0;
	} else {
	ret = write_blk(info, *blk, buf);
	if (ret < 0)
	quota_error(dquot->dq_sb,
	"Can't write quota tree block %u",
	*blk);
	}
	}
	out_buf:
	kfree(buf);
	return ret;
	}

	/* Delete dquot from tree */
	int qtree_delete_dquot(struct qtree_mem_dqinfo info, struct dquot dquot)
	{
	uint tmp = QT_TREEOFF;

	if (!dquot->dq_off) /* Even not allocated? */
	return 0;
	return remove_tree(info, dquot, &tmp, 0);
	}
	EXPORT_SYMBOL(qtree_delete_dquot);

	/* Find entry in block */
	static loff_t find_block_dqentry(struct qtree_mem_dqinfo *info,
	struct dquot *dquot, uint blk)
	{
	char *buf = getdqbuf(info->dqi_usable_bs);
	loff_t ret = 0;
	int i;
	char *ddquot;

	if (!buf)
	return -ENOMEM;
	ret = read_blk(info, blk, buf);
	if (ret < 0) {
	quota_error(dquot->dq_sb, "Can't read quota tree "
	"block %u", blk);
	goto out_buf;
	}
	ddquot = buf + sizeof(struct qt_disk_dqdbheader);
	for (i = 0; i < qtree_dqstr_in_blk(info); i++) {
	if (info->dqi_ops->is_id(ddquot, dquot))
	break;
	ddquot += info->dqi_entry_size;
	}
	if (i == qtree_dqstr_in_blk(info)) {
	quota_error(dquot->dq_sb,
	"Quota for id %u referenced but not present",
	from_kqid(&init_user_ns, dquot->dq_id));
	ret = -EIO;
	goto out_buf;
	} else {
	ret = ((loff_t)blk << info->dqi_blocksize_bits) + sizeof(struct
	qt_disk_dqdbheader) + i * info->dqi_entry_size;
	}
	out_buf:
	kfree(buf);
	return ret;
	}

	/* Find entry for given id in the tree */
	static loff_t find_tree_dqentry(struct qtree_mem_dqinfo *info,
	struct dquot *dquot, uint blk, int depth)
	{
	char *buf = getdqbuf(info->dqi_usable_bs);
	loff_t ret = 0;
	__le32 ref = (__le32 )buf;

	if (!buf)
	return -ENOMEM;
	ret = read_blk(info, blk, buf);
	if (ret < 0) {
	quota_error(dquot->dq_sb, "Can't read quota tree block %u",
	blk);
	goto out_buf;
	}
	ret = 0;
	blk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
	if (!blk) /* No reference? */
	goto out_buf;
	if (blk < QT_TREEOFF \|\| blk >= info->dqi_blocks) {
	quota_error(dquot->dq_sb, "Getting block too big (%u >= %u)",
	blk, info->dqi_blocks);
	ret = -EUCLEAN;
	goto out_buf;
	}

	if (depth < info->dqi_qtree_depth - 1)
	ret = find_tree_dqentry(info, dquot, blk, depth+1);
	else
	ret = find_block_dqentry(info, dquot, blk);
	out_buf:
	kfree(buf);
	return ret;
	}

	/* Find entry for given id in the tree - wrapper function */
	static inline loff_t find_dqentry(struct qtree_mem_dqinfo *info,
	struct dquot *dquot)
	{
	return find_tree_dqentry(info, dquot, QT_TREEOFF, 0);
	}

	int qtree_read_dquot(struct qtree_mem_dqinfo info, struct dquot dquot)
	{
	int type = dquot->dq_id.type;
	struct super_block *sb = dquot->dq_sb;
	loff_t offset;
	char *ddquot;
	int ret = 0;

	#ifdef __QUOTA_QT_PARANOIA
	/* Invalidated quota? */
	if (!sb_dqopt(dquot->dq_sb)->files[type]) {
	quota_error(sb, "Quota invalidated while reading!");
	return -EIO;
	}
	#endif
	/* Do we know offset of the dquot entry in the quota file? */
	if (!dquot->dq_off) {
	offset = find_dqentry(info, dquot);
	if (offset <= 0) { /* Entry not present? */
	if (offset < 0)
	quota_error(sb,"Can't read quota structure "
	"for id %u",
	from_kqid(&init_user_ns,
	dquot->dq_id));
	dquot->dq_off = 0;
	set_bit(DQ_FAKE_B, &dquot->dq_flags);
	memset(&dquot->dq_dqb, 0, sizeof(struct mem_dqblk));
	ret = offset;
	goto out;
	}
	dquot->dq_off = offset;
	}
	ddquot = getdqbuf(info->dqi_entry_size);
	if (!ddquot)
	return -ENOMEM;
	ret = sb->s_op->quota_read(sb, type, ddquot, info->dqi_entry_size,
	dquot->dq_off);
	if (ret != info->dqi_entry_size) {
	if (ret >= 0)
	ret = -EIO;
	quota_error(sb, "Error while reading quota structure for id %u",
	from_kqid(&init_user_ns, dquot->dq_id));
	set_bit(DQ_FAKE_B, &dquot->dq_flags);
	memset(&dquot->dq_dqb, 0, sizeof(struct mem_dqblk));
	kfree(ddquot);
	goto out;
	}
	spin_lock(&dquot->dq_dqb_lock);
	info->dqi_ops->disk2mem_dqblk(dquot, ddquot);
	if (!dquot->dq_dqb.dqb_bhardlimit &&
	!dquot->dq_dqb.dqb_bsoftlimit &&
	!dquot->dq_dqb.dqb_ihardlimit &&
	!dquot->dq_dqb.dqb_isoftlimit)
	set_bit(DQ_FAKE_B, &dquot->dq_flags);
	spin_unlock(&dquot->dq_dqb_lock);
	kfree(ddquot);
	out:
	dqstats_inc(DQST_READS);
	return ret;
	}
	EXPORT_SYMBOL(qtree_read_dquot);

	/* Check whether dquot should not be deleted. We know we are
	* the only one operating on dquot (thanks to dq_lock) */
	int qtree_release_dquot(struct qtree_mem_dqinfo info, struct dquot dquot)
	{
	if (test_bit(DQ_FAKE_B, &dquot->dq_flags) &&
	!(dquot->dq_dqb.dqb_curinodes \| dquot->dq_dqb.dqb_curspace))
	return qtree_delete_dquot(info, dquot);
	return 0;
	}
	EXPORT_SYMBOL(qtree_release_dquot);

	static int find_next_id(struct qtree_mem_dqinfo info, qid_t id,
	unsigned int blk, int depth)
	{
	char *buf = getdqbuf(info->dqi_usable_bs);
	__le32 ref = (__le32 )buf;
	ssize_t ret;
	unsigned int epb = info->dqi_usable_bs >> 2;
	unsigned int level_inc = 1;
	int i;

	if (!buf)
	return -ENOMEM;

	for (i = depth; i < info->dqi_qtree_depth - 1; i++)
	level_inc *= epb;

	ret = read_blk(info, blk, buf);
	if (ret < 0) {
	quota_error(info->dqi_sb,
	"Can't read quota tree block %u", blk);
	goto out_buf;
	}
	for (i = __get_index(info, *id, depth); i < epb; i++) {
	if (ref[i] == cpu_to_le32(0)) {
	*id += level_inc;
	continue;
	}
	if (depth == info->dqi_qtree_depth - 1) {
	ret = 0;
	goto out_buf;
	}
	ret = find_next_id(info, id, le32_to_cpu(ref[i]), depth + 1);
	if (ret != -ENOENT)
	break;
	}
	if (i == epb) {
	ret = -ENOENT;
	goto out_buf;
	}
	out_buf:
	kfree(buf);
	return ret;
	}

	int qtree_get_next_id(struct qtree_mem_dqinfo info, struct kqid qid)
	{
	qid_t id = from_kqid(&init_user_ns, *qid);
	int ret;

	ret = find_next_id(info, &id, QT_TREEOFF, 0);
	if (ret < 0)
	return ret;
	*qid = make_kqid(&init_user_ns, qid->type, id);
	return 0;
	}
	EXPORT_SYMBOL(qtree_get_next_id);