Note that this behavior is currently deprecated and may go away in
          future. Please use notification via netlink socket instead.
 
+# Generic support for tree structured quota files. Seleted when needed.
+config QUOTA_TREE
+        tristate
+
 config QFMT_V1
        tristate "Old quota format support"
        depends on QUOTA
 config QFMT_V2
        tristate "Quota format v2 support"
        depends on QUOTA
+       select QUOTA_TREE
        help
          This quota format allows using quotas with 32-bit UIDs/GIDs. If you
          need this functionality say Y here.
 
 obj-$(CONFIG_QUOTA)            += dquot.o
 obj-$(CONFIG_QFMT_V1)          += quota_v1.o
 obj-$(CONFIG_QFMT_V2)          += quota_v2.o
+obj-$(CONFIG_QUOTA_TREE)       += quota_tree.o
 obj-$(CONFIG_QUOTACTL)         += quota.o
 
 obj-$(CONFIG_PROC_FS)          += proc/
 
--- /dev/null
+/*
+ *     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
+
+typedef char *dqbuf_t;
+
+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;
+}
+
+/* Number of entries in one blocks */
+static inline 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 dqbuf_t getdqbuf(size_t size)
+{
+       dqbuf_t buf = kmalloc(size, GFP_NOFS);
+       if (!buf)
+               printk(KERN_WARNING "VFS: Not enough memory for quota buffers.\n");
+       return buf;
+}
+
+static inline void freedqbuf(dqbuf_t buf)
+{
+       kfree(buf);
+}
+
+static inline ssize_t read_blk(struct qtree_mem_dqinfo *info, uint blk, dqbuf_t 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, (char *)buf,
+              info->dqi_usable_bs, blk << info->dqi_blocksize_bits);
+}
+
+static inline ssize_t write_blk(struct qtree_mem_dqinfo *info, uint blk, dqbuf_t buf)
+{
+       struct super_block *sb = info->dqi_sb;
+
+       return sb->s_op->quota_write(sb, info->dqi_type, (char *)buf,
+              info->dqi_usable_bs, blk << info->dqi_blocksize_bits);
+}
+
+/* Remove empty block from list and return it */
+static int get_free_dqblk(struct qtree_mem_dqinfo *info)
+{
+       dqbuf_t 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:
+       freedqbuf(buf);
+       return ret;
+}
+
+/* Insert empty block to the list */
+static int put_free_dqblk(struct qtree_mem_dqinfo *info, dqbuf_t 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, dqbuf_t buf, uint blk)
+{
+       dqbuf_t 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);
+       }
+       freedqbuf(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)
+               printk(KERN_ERR "VFS: Can't write block (%u) with free entries.\n", blk);
+       return 0;
+out_buf:
+       freedqbuf(tmpbuf);
+       return err;
+}
+
+/* Insert given block to the beginning of list with free entries */
+static int insert_free_dqentry(struct qtree_mem_dqinfo *info, dqbuf_t buf, uint blk)
+{
+       dqbuf_t 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;
+       }
+       freedqbuf(tmpbuf);
+       info->dqi_free_entry = blk;
+       mark_info_dirty(info->dqi_sb, info->dqi_type);
+       return 0;
+out_buf:
+       freedqbuf(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;
+       dqbuf_t 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;
+                       freedqbuf(buf);
+                       return 0;
+               }
+               memset(buf, 0, info->dqi_usable_bs);
+               /* This is enough as block is already zeroed and entry list is empty... */
+               info->dqi_free_entry = blk;
+               mark_info_dirty(dquot->dq_sb, dquot->dq_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) {
+                       printk(KERN_ERR "VFS: find_free_dqentry(): Can't "
+                              "remove block (%u) from entry free list.\n",
+                              blk);
+                       goto out_buf;
+               }
+       }
+       le16_add_cpu(&dh->dqdh_entries, 1);
+       /* Find free structure in block */
+       for (i = 0, ddquot = ((char *)buf) + sizeof(struct qt_disk_dqdbheader);
+            i < qtree_dqstr_in_blk(info) && !qtree_entry_unused(info, ddquot);
+            i++, ddquot += info->dqi_entry_size);
+#ifdef __QUOTA_QT_PARANOIA
+       if (i == qtree_dqstr_in_blk(info)) {
+               printk(KERN_ERR "VFS: find_free_dqentry(): Data block full "
+                               "but it shouldn't.\n");
+               *err = -EIO;
+               goto out_buf;
+       }
+#endif
+       *err = write_blk(info, blk, buf);
+       if (*err < 0) {
+               printk(KERN_ERR "VFS: find_free_dqentry(): Can't write quota "
+                               "data block %u.\n", blk);
+               goto out_buf;
+       }
+       dquot->dq_off = (blk << info->dqi_blocksize_bits) +
+                       sizeof(struct qt_disk_dqdbheader) +
+                       i * info->dqi_entry_size;
+       freedqbuf(buf);
+       return blk;
+out_buf:
+       freedqbuf(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)
+{
+       dqbuf_t 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) {
+                       printk(KERN_ERR "VFS: Can't read tree quota block "
+                                       "%u.\n", *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) {
+                       printk(KERN_ERR "VFS: Inserting already present quota "
+                                       "entry (block %u).\n",
+                              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:
+       freedqbuf(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;
+       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_type;
+       struct super_block *sb = dquot->dq_sb;
+       ssize_t ret;
+       dqbuf_t ddquot = getdqbuf(info->dqi_entry_size);
+
+       if (!ddquot)
+               return -ENOMEM;
+
+       /* dq_off is guarded by dqio_mutex */
+       if (!dquot->dq_off) {
+               ret = dq_insert_tree(info, dquot);
+               if (ret < 0) {
+                       printk(KERN_ERR "VFS: Error %zd occurred while "
+                                       "creating quota.\n", ret);
+                       freedqbuf(ddquot);
+                       return ret;
+               }
+       }
+       spin_lock(&dq_data_lock);
+       info->dqi_ops->mem2disk_dqblk(ddquot, dquot);
+       spin_unlock(&dq_data_lock);
+       ret = sb->s_op->quota_write(sb, type, (char *)ddquot,
+                                       info->dqi_entry_size, dquot->dq_off);
+       if (ret != info->dqi_entry_size) {
+               printk(KERN_WARNING "VFS: dquota write failed on dev %s\n",
+                      sb->s_id);
+               if (ret >= 0)
+                       ret = -ENOSPC;
+       } else {
+               ret = 0;
+       }
+       dqstats.writes++;
+       freedqbuf(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;
+       dqbuf_t buf = getdqbuf(info->dqi_usable_bs);
+       int ret = 0;
+
+       if (!buf)
+               return -ENOMEM;
+       if (dquot->dq_off >> info->dqi_blocksize_bits != blk) {
+               printk(KERN_ERR "VFS: Quota structure has offset to other "
+                 "block (%u) than it should (%u).\n", blk,
+                 (uint)(dquot->dq_off >> info->dqi_blocksize_bits));
+               goto out_buf;
+       }
+       ret = read_blk(info, blk, buf);
+       if (ret < 0) {
+               printk(KERN_ERR "VFS: Can't read quota data block %u\n", 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) {
+                       printk(KERN_ERR "VFS: Can't move quota data block (%u) "
+                         "to free list.\n", 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) {
+                               printk(KERN_ERR "VFS: Can't insert quota data "
+                                      "block (%u) to free entry list.\n", blk);
+                               goto out_buf;
+                       }
+               } else {
+                       ret = write_blk(info, blk, buf);
+                       if (ret < 0) {
+                               printk(KERN_ERR "VFS: Can't write quota data "
+                                 "block %u\n", blk);
+                               goto out_buf;
+                       }
+               }
+       }
+       dquot->dq_off = 0;      /* Quota is now unattached */
+out_buf:
+       freedqbuf(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)
+{
+       dqbuf_t 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) {
+               printk(KERN_ERR "VFS: Can't read quota data block %u\n", *blk);
+               goto out_buf;
+       }
+       newblk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
+       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)
+                               printk(KERN_ERR "VFS: Can't write quota tree "
+                                 "block %u.\n", *blk);
+               }
+       }
+out_buf:
+       freedqbuf(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)
+{
+       dqbuf_t 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) {
+               printk(KERN_ERR "VFS: Can't read quota tree block %u.\n", blk);
+               goto out_buf;
+       }
+       for (i = 0, ddquot = ((char *)buf) + sizeof(struct qt_disk_dqdbheader);
+            i < qtree_dqstr_in_blk(info) && !info->dqi_ops->is_id(ddquot, dquot);
+            i++, ddquot += info->dqi_entry_size);
+       if (i == qtree_dqstr_in_blk(info)) {
+               printk(KERN_ERR "VFS: Quota for id %u referenced "
+                 "but not present.\n", dquot->dq_id);
+               ret = -EIO;
+               goto out_buf;
+       } else {
+               ret = (blk << info->dqi_blocksize_bits) + sizeof(struct
+                 qt_disk_dqdbheader) + i * info->dqi_entry_size;
+       }
+out_buf:
+       freedqbuf(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)
+{
+       dqbuf_t 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) {
+               printk(KERN_ERR "VFS: Can't read quota tree block %u.\n", 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 (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:
+       freedqbuf(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_type;
+       struct super_block *sb = dquot->dq_sb;
+       loff_t offset;
+       dqbuf_t ddquot;
+       int ret = 0;
+
+#ifdef __QUOTA_QT_PARANOIA
+       /* Invalidated quota? */
+       if (!sb_dqopt(dquot->dq_sb)->files[type]) {
+               printk(KERN_ERR "VFS: Quota invalidated while reading!\n");
+               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)
+                               printk(KERN_ERR "VFS: Can't read quota "
+                                 "structure for id %u.\n", 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, (char *)ddquot,
+                                  info->dqi_entry_size, dquot->dq_off);
+       if (ret != info->dqi_entry_size) {
+               if (ret >= 0)
+                       ret = -EIO;
+               printk(KERN_ERR "VFS: Error while reading quota "
+                               "structure for id %u.\n", dquot->dq_id);
+               set_bit(DQ_FAKE_B, &dquot->dq_flags);
+               memset(&dquot->dq_dqb, 0, sizeof(struct mem_dqblk));
+               freedqbuf(ddquot);
+               goto out;
+       }
+       spin_lock(&dq_data_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(&dq_data_lock);
+       freedqbuf(ddquot);
+out:
+       dqstats.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);
 
--- /dev/null
+/*
+ *     Definitions of structures for vfsv0 quota format
+ */
+
+#ifndef _LINUX_QUOTA_TREE_H
+#define _LINUX_QUOTA_TREE_H
+
+#include <linux/types.h>
+#include <linux/quota.h>
+
+/*
+ *  Structure of header of block with quota structures. It is padded to 16 bytes so
+ *  there will be space for exactly 21 quota-entries in a block
+ */
+struct qt_disk_dqdbheader {
+       __le32 dqdh_next_free;  /* Number of next block with free entry */
+       __le32 dqdh_prev_free;  /* Number of previous block with free entry */
+       __le16 dqdh_entries;    /* Number of valid entries in block */
+       __le16 dqdh_pad1;
+       __le32 dqdh_pad2;
+};
+
+#define QT_TREEOFF     1               /* Offset of tree in file in blocks */
+
+#endif /* _LINUX_QUOTAIO_TREE_H */
 
 
 #include <asm/byteorder.h>
 
+#include "quota_tree.h"
 #include "quotaio_v2.h"
 
 MODULE_AUTHOR("Jan Kara");
 
 #define __QUOTA_V2_PARANOIA
 
-typedef char *dqbuf_t;
+static void v2_mem2diskdqb(void *dp, struct dquot *dquot);
+static void v2_disk2memdqb(struct dquot *dquot, void *dp);
+static int v2_is_id(void *dp, struct dquot *dquot);
 
-#define GETIDINDEX(id, depth) (((id) >> ((V2_DQTREEDEPTH-(depth)-1)*8)) & 0xff)
-#define GETENTRIES(buf) ((struct v2_disk_dqblk *)(((char *)buf)+sizeof(struct v2_disk_dqdbheader)))
+static struct qtree_fmt_operations v2_qtree_ops = {
+       .mem2disk_dqblk = v2_mem2diskdqb,
+       .disk2mem_dqblk = v2_disk2memdqb,
+       .is_id = v2_is_id,
+};
 
 #define QUOTABLOCK_BITS 10
 #define QUOTABLOCK_SIZE (1 << QUOTABLOCK_BITS)
 static int v2_read_file_info(struct super_block *sb, int type)
 {
        struct v2_disk_dqinfo dinfo;
-       struct mem_dqinfo *info = sb_dqopt(sb)->info+type;
+       struct mem_dqinfo *info = sb_dqinfo(sb, type);
        ssize_t size;
 
        size = sb->s_op->quota_read(sb, type, (char *)&dinfo,
        info->dqi_bgrace = le32_to_cpu(dinfo.dqi_bgrace);
        info->dqi_igrace = le32_to_cpu(dinfo.dqi_igrace);
        info->dqi_flags = le32_to_cpu(dinfo.dqi_flags);
-       info->u.v2_i.dqi_blocks = le32_to_cpu(dinfo.dqi_blocks);
-       info->u.v2_i.dqi_free_blk = le32_to_cpu(dinfo.dqi_free_blk);
-       info->u.v2_i.dqi_free_entry = le32_to_cpu(dinfo.dqi_free_entry);
+       info->u.v2_i.i.dqi_sb = sb;
+       info->u.v2_i.i.dqi_type = type;
+       info->u.v2_i.i.dqi_blocks = le32_to_cpu(dinfo.dqi_blocks);
+       info->u.v2_i.i.dqi_free_blk = le32_to_cpu(dinfo.dqi_free_blk);
+       info->u.v2_i.i.dqi_free_entry = le32_to_cpu(dinfo.dqi_free_entry);
+       info->u.v2_i.i.dqi_blocksize_bits = V2_DQBLKSIZE_BITS;
+       info->u.v2_i.i.dqi_usable_bs = 1 << V2_DQBLKSIZE_BITS;
+       info->u.v2_i.i.dqi_qtree_depth = qtree_depth(&info->u.v2_i.i);
+       info->u.v2_i.i.dqi_entry_size = sizeof(struct v2_disk_dqblk);
+       info->u.v2_i.i.dqi_ops = &v2_qtree_ops;
        return 0;
 }
 
 static int v2_write_file_info(struct super_block *sb, int type)
 {
        struct v2_disk_dqinfo dinfo;
-       struct mem_dqinfo *info = sb_dqopt(sb)->info+type;
+       struct mem_dqinfo *info = sb_dqinfo(sb, type);
        ssize_t size;
 
        spin_lock(&dq_data_lock);
        dinfo.dqi_igrace = cpu_to_le32(info->dqi_igrace);
        dinfo.dqi_flags = cpu_to_le32(info->dqi_flags & DQF_MASK);
        spin_unlock(&dq_data_lock);
-       dinfo.dqi_blocks = cpu_to_le32(info->u.v2_i.dqi_blocks);
-       dinfo.dqi_free_blk = cpu_to_le32(info->u.v2_i.dqi_free_blk);
-       dinfo.dqi_free_entry = cpu_to_le32(info->u.v2_i.dqi_free_entry);
+       dinfo.dqi_blocks = cpu_to_le32(info->u.v2_i.i.dqi_blocks);
+       dinfo.dqi_free_blk = cpu_to_le32(info->u.v2_i.i.dqi_free_blk);
+       dinfo.dqi_free_entry = cpu_to_le32(info->u.v2_i.i.dqi_free_entry);
        size = sb->s_op->quota_write(sb, type, (char *)&dinfo,
               sizeof(struct v2_disk_dqinfo), V2_DQINFOOFF);
        if (size != sizeof(struct v2_disk_dqinfo)) {
        return 0;
 }
 
-static void disk2memdqb(struct mem_dqblk *m, struct v2_disk_dqblk *d)
+static void v2_disk2memdqb(struct dquot *dquot, void *dp)
 {
+       struct v2_disk_dqblk *d = dp, empty;
+       struct mem_dqblk *m = &dquot->dq_dqb;
+
        m->dqb_ihardlimit = le32_to_cpu(d->dqb_ihardlimit);
        m->dqb_isoftlimit = le32_to_cpu(d->dqb_isoftlimit);
        m->dqb_curinodes = le32_to_cpu(d->dqb_curinodes);
        m->dqb_bsoftlimit = v2_qbtos(le32_to_cpu(d->dqb_bsoftlimit));
        m->dqb_curspace = le64_to_cpu(d->dqb_curspace);
        m->dqb_btime = le64_to_cpu(d->dqb_btime);
+       /* We need to escape back all-zero structure */
+       memset(&empty, 0, sizeof(struct v2_disk_dqblk));
+       empty.dqb_itime = cpu_to_le64(1);
+       if (!memcmp(&empty, dp, sizeof(struct v2_disk_dqblk)))
+               m->dqb_itime = 0;
 }
 
-static void mem2diskdqb(struct v2_disk_dqblk *d, struct mem_dqblk *m, qid_t id)
+static void v2_mem2diskdqb(void *dp, struct dquot *dquot)
 {
+       struct v2_disk_dqblk *d = dp;
+       struct mem_dqblk *m = &dquot->dq_dqb;
+       struct qtree_mem_dqinfo *info =
+                       &sb_dqinfo(dquot->dq_sb, dquot->dq_type)->u.v2_i.i;
+
        d->dqb_ihardlimit = cpu_to_le32(m->dqb_ihardlimit);
        d->dqb_isoftlimit = cpu_to_le32(m->dqb_isoftlimit);
        d->dqb_curinodes = cpu_to_le32(m->dqb_curinodes);
        d->dqb_bsoftlimit = cpu_to_le32(v2_stoqb(m->dqb_bsoftlimit));
        d->dqb_curspace = cpu_to_le64(m->dqb_curspace);
        d->dqb_btime = cpu_to_le64(m->dqb_btime);
-       d->dqb_id = cpu_to_le32(id);
-}
-
-static dqbuf_t getdqbuf(void)
-{
-       dqbuf_t buf = kmalloc(V2_DQBLKSIZE, GFP_NOFS);
-       if (!buf)
-               printk(KERN_WARNING "VFS: Not enough memory for quota buffers.\n");
-       return buf;
-}
-
-static inline void freedqbuf(dqbuf_t buf)
-{
-       kfree(buf);
-}
-
-static inline ssize_t read_blk(struct super_block *sb, int type, uint blk, dqbuf_t buf)
-{
-       memset(buf, 0, V2_DQBLKSIZE);
-       return sb->s_op->quota_read(sb, type, (char *)buf,
-              V2_DQBLKSIZE, blk << V2_DQBLKSIZE_BITS);
-}
-
-static inline ssize_t write_blk(struct super_block *sb, int type, uint blk, dqbuf_t buf)
-{
-       return sb->s_op->quota_write(sb, type, (char *)buf,
-              V2_DQBLKSIZE, blk << V2_DQBLKSIZE_BITS);
-}
-
-/* Remove empty block from list and return it */
-static int get_free_dqblk(struct super_block *sb, int type)
-{
-       dqbuf_t buf = getdqbuf();
-       struct mem_dqinfo *info = sb_dqinfo(sb, type);
-       struct v2_disk_dqdbheader *dh = (struct v2_disk_dqdbheader *)buf;
-       int ret, blk;
-
-       if (!buf)
-               return -ENOMEM;
-       if (info->u.v2_i.dqi_free_blk) {
-               blk = info->u.v2_i.dqi_free_blk;
-               if ((ret = read_blk(sb, type, blk, buf)) < 0)
-                       goto out_buf;
-               info->u.v2_i.dqi_free_blk = le32_to_cpu(dh->dqdh_next_free);
-       }
-       else {
-               memset(buf, 0, V2_DQBLKSIZE);
-               /* Assure block allocation... */
-               if ((ret = write_blk(sb, type, info->u.v2_i.dqi_blocks, buf)) < 0)
-                       goto out_buf;
-               blk = info->u.v2_i.dqi_blocks++;
-       }
-       mark_info_dirty(sb, type);
-       ret = blk;
-out_buf:
-       freedqbuf(buf);
-       return ret;
-}
-
-/* Insert empty block to the list */
-static int put_free_dqblk(struct super_block *sb, int type, dqbuf_t buf, uint blk)
-{
-       struct mem_dqinfo *info = sb_dqinfo(sb, type);
-       struct v2_disk_dqdbheader *dh = (struct v2_disk_dqdbheader *)buf;
-       int err;
-
-       dh->dqdh_next_free = cpu_to_le32(info->u.v2_i.dqi_free_blk);
-       dh->dqdh_prev_free = cpu_to_le32(0);
-       dh->dqdh_entries = cpu_to_le16(0);
-       info->u.v2_i.dqi_free_blk = blk;
-       mark_info_dirty(sb, type);
-       /* Some strange block. We had better leave it... */
-       if ((err = write_blk(sb, type, blk, buf)) < 0)
-               return err;
-       return 0;
+       d->dqb_id = cpu_to_le32(dquot->dq_id);
+       if (qtree_entry_unused(info, dp))
+               d->dqb_itime = cpu_to_le64(1);
 }
 
-/* Remove given block from the list of blocks with free entries */
-static int remove_free_dqentry(struct super_block *sb, int type, dqbuf_t buf, uint blk)
+static int v2_is_id(void *dp, struct dquot *dquot)
 {
-       dqbuf_t tmpbuf = getdqbuf();
-       struct mem_dqinfo *info = sb_dqinfo(sb, type);
-       struct v2_disk_dqdbheader *dh = (struct v2_disk_dqdbheader *)buf;
-       uint nextblk = le32_to_cpu(dh->dqdh_next_free), prevblk = le32_to_cpu(dh->dqdh_prev_free);
-       int err;
+       struct v2_disk_dqblk *d = dp;
+       struct qtree_mem_dqinfo *info =
+                       &sb_dqinfo(dquot->dq_sb, dquot->dq_type)->u.v2_i.i;
 
-       if (!tmpbuf)
-               return -ENOMEM;
-       if (nextblk) {
-               if ((err = read_blk(sb, type, nextblk, tmpbuf)) < 0)
-                       goto out_buf;
-               ((struct v2_disk_dqdbheader *)tmpbuf)->dqdh_prev_free = dh->dqdh_prev_free;
-               if ((err = write_blk(sb, type, nextblk, tmpbuf)) < 0)
-                       goto out_buf;
-       }
-       if (prevblk) {
-               if ((err = read_blk(sb, type, prevblk, tmpbuf)) < 0)
-                       goto out_buf;
-               ((struct v2_disk_dqdbheader *)tmpbuf)->dqdh_next_free = dh->dqdh_next_free;
-               if ((err = write_blk(sb, type, prevblk, tmpbuf)) < 0)
-                       goto out_buf;
-       }
-       else {
-               info->u.v2_i.dqi_free_entry = nextblk;
-               mark_info_dirty(sb, type);
-       }
-       freedqbuf(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(sb, type, blk, buf) < 0)
-               printk(KERN_ERR "VFS: Can't write block (%u) with free entries.\n", blk);
-       return 0;
-out_buf:
-       freedqbuf(tmpbuf);
-       return err;
-}
-
-/* Insert given block to the beginning of list with free entries */
-static int insert_free_dqentry(struct super_block *sb, int type, dqbuf_t buf, uint blk)
-{
-       dqbuf_t tmpbuf = getdqbuf();
-       struct mem_dqinfo *info = sb_dqinfo(sb, type);
-       struct v2_disk_dqdbheader *dh = (struct v2_disk_dqdbheader *)buf;
-       int err;
-
-       if (!tmpbuf)
-               return -ENOMEM;
-       dh->dqdh_next_free = cpu_to_le32(info->u.v2_i.dqi_free_entry);
-       dh->dqdh_prev_free = cpu_to_le32(0);
-       if ((err = write_blk(sb, type, blk, buf)) < 0)
-               goto out_buf;
-       if (info->u.v2_i.dqi_free_entry) {
-               if ((err = read_blk(sb, type, info->u.v2_i.dqi_free_entry, tmpbuf)) < 0)
-                       goto out_buf;
-               ((struct v2_disk_dqdbheader *)tmpbuf)->dqdh_prev_free = cpu_to_le32(blk);
-               if ((err = write_blk(sb, type, info->u.v2_i.dqi_free_entry, tmpbuf)) < 0)
-                       goto out_buf;
-       }
-       freedqbuf(tmpbuf);
-       info->u.v2_i.dqi_free_entry = blk;
-       mark_info_dirty(sb, type);
-       return 0;
-out_buf:
-       freedqbuf(tmpbuf);
-       return err;
-}
-
-/* Find space for dquot */
-static uint find_free_dqentry(struct dquot *dquot, int *err)
-{
-       struct super_block *sb = dquot->dq_sb;
-       struct mem_dqinfo *info = sb_dqopt(sb)->info+dquot->dq_type;
-       uint blk, i;
-       struct v2_disk_dqdbheader *dh;
-       struct v2_disk_dqblk *ddquot;
-       struct v2_disk_dqblk fakedquot;
-       dqbuf_t buf;
-
-       *err = 0;
-       if (!(buf = getdqbuf())) {
-               *err = -ENOMEM;
+       if (qtree_entry_unused(info, dp))
                return 0;
-       }
-       dh = (struct v2_disk_dqdbheader *)buf;
-       ddquot = GETENTRIES(buf);
-       if (info->u.v2_i.dqi_free_entry) {
-               blk = info->u.v2_i.dqi_free_entry;
-               if ((*err = read_blk(sb, dquot->dq_type, blk, buf)) < 0)
-                       goto out_buf;
-       }
-       else {
-               blk = get_free_dqblk(sb, dquot->dq_type);
-               if ((int)blk < 0) {
-                       *err = blk;
-                       freedqbuf(buf);
-                       return 0;
-               }
-               memset(buf, 0, V2_DQBLKSIZE);
-               /* This is enough as block is already zeroed and entry list is empty... */
-               info->u.v2_i.dqi_free_entry = blk;
-               mark_info_dirty(sb, dquot->dq_type);
-       }
-       if (le16_to_cpu(dh->dqdh_entries)+1 >= V2_DQSTRINBLK)   /* Block will be full? */
-               if ((*err = remove_free_dqentry(sb, dquot->dq_type, buf, blk)) < 0) {
-                       printk(KERN_ERR "VFS: find_free_dqentry(): Can't remove block (%u) from entry free list.\n", blk);
-                       goto out_buf;
-               }
-       le16_add_cpu(&dh->dqdh_entries, 1);
-       memset(&fakedquot, 0, sizeof(struct v2_disk_dqblk));
-       /* Find free structure in block */
-       for (i = 0; i < V2_DQSTRINBLK && memcmp(&fakedquot, ddquot+i, sizeof(struct v2_disk_dqblk)); i++);
-#ifdef __QUOTA_V2_PARANOIA
-       if (i == V2_DQSTRINBLK) {
-               printk(KERN_ERR "VFS: find_free_dqentry(): Data block full but it shouldn't.\n");
-               *err = -EIO;
-               goto out_buf;
-       }
-#endif
-       if ((*err = write_blk(sb, dquot->dq_type, blk, buf)) < 0) {
-               printk(KERN_ERR "VFS: find_free_dqentry(): Can't write quota data block %u.\n", blk);
-               goto out_buf;
-       }
-       dquot->dq_off = (blk<<V2_DQBLKSIZE_BITS)+sizeof(struct v2_disk_dqdbheader)+i*sizeof(struct v2_disk_dqblk);
-       freedqbuf(buf);
-       return blk;
-out_buf:
-       freedqbuf(buf);
-       return 0;
+       return le32_to_cpu(d->dqb_id) == dquot->dq_id;
 }
 
-/* Insert reference to structure into the trie */
-static int do_insert_tree(struct dquot *dquot, uint *treeblk, int depth)
-{
-       struct super_block *sb = dquot->dq_sb;
-       dqbuf_t buf;
-       int ret = 0, newson = 0, newact = 0;
-       __le32 *ref;
-       uint newblk;
-
-       if (!(buf = getdqbuf()))
-               return -ENOMEM;
-       if (!*treeblk) {
-               ret = get_free_dqblk(sb, dquot->dq_type);
-               if (ret < 0)
-                       goto out_buf;
-               *treeblk = ret;
-               memset(buf, 0, V2_DQBLKSIZE);
-               newact = 1;
-       }
-       else {
-               if ((ret = read_blk(sb, dquot->dq_type, *treeblk, buf)) < 0) {
-                       printk(KERN_ERR "VFS: Can't read tree quota block %u.\n", *treeblk);
-                       goto out_buf;
-               }
-       }
-       ref = (__le32 *)buf;
-       newblk = le32_to_cpu(ref[GETIDINDEX(dquot->dq_id, depth)]);
-       if (!newblk)
-               newson = 1;
-       if (depth == V2_DQTREEDEPTH-1) {
-#ifdef __QUOTA_V2_PARANOIA
-               if (newblk) {
-                       printk(KERN_ERR "VFS: Inserting already present quota entry (block %u).\n", le32_to_cpu(ref[GETIDINDEX(dquot->dq_id, depth)]));
-                       ret = -EIO;
-                       goto out_buf;
-               }
-#endif
-               newblk = find_free_dqentry(dquot, &ret);
-       }
-       else
-               ret = do_insert_tree(dquot, &newblk, depth+1);
-       if (newson && ret >= 0) {
-               ref[GETIDINDEX(dquot->dq_id, depth)] = cpu_to_le32(newblk);
-               ret = write_blk(sb, dquot->dq_type, *treeblk, buf);
-       }
-       else if (newact && ret < 0)
-               put_free_dqblk(sb, dquot->dq_type, buf, *treeblk);
-out_buf:
-       freedqbuf(buf);
-       return ret;
-}
-
-/* Wrapper for inserting quota structure into tree */
-static inline int dq_insert_tree(struct dquot *dquot)
+static int v2_read_dquot(struct dquot *dquot)
 {
-       int tmp = V2_DQTREEOFF;
-       return do_insert_tree(dquot, &tmp, 0);
+       return qtree_read_dquot(&sb_dqinfo(dquot->dq_sb, dquot->dq_type)->u.v2_i.i, dquot);
 }
 
-/*
- *     We don't have to be afraid of deadlocks as we never have quotas on quota files...
- */
 static int v2_write_dquot(struct dquot *dquot)
 {
-       int type = dquot->dq_type;
-       ssize_t ret;
-       struct v2_disk_dqblk ddquot, empty;
-
-       /* dq_off is guarded by dqio_mutex */
-       if (!dquot->dq_off)
-               if ((ret = dq_insert_tree(dquot)) < 0) {
-                       printk(KERN_ERR "VFS: Error %zd occurred while creating quota.\n", ret);
-                       return ret;
-               }
-       spin_lock(&dq_data_lock);
-       mem2diskdqb(&ddquot, &dquot->dq_dqb, dquot->dq_id);
-       /* Argh... We may need to write structure full of zeroes but that would be
-        * treated as an empty place by the rest of the code. Format change would
-        * be definitely cleaner but the problems probably are not worth it */
-       memset(&empty, 0, sizeof(struct v2_disk_dqblk));
-       if (!memcmp(&empty, &ddquot, sizeof(struct v2_disk_dqblk)))
-               ddquot.dqb_itime = cpu_to_le64(1);
-       spin_unlock(&dq_data_lock);
-       ret = dquot->dq_sb->s_op->quota_write(dquot->dq_sb, type,
-             (char *)&ddquot, sizeof(struct v2_disk_dqblk), dquot->dq_off);
-       if (ret != sizeof(struct v2_disk_dqblk)) {
-               printk(KERN_WARNING "VFS: dquota write failed on dev %s\n", dquot->dq_sb->s_id);
-               if (ret >= 0)
-                       ret = -ENOSPC;
-       }
-       else
-               ret = 0;
-       dqstats.writes++;
-
-       return ret;
+       return qtree_write_dquot(&sb_dqinfo(dquot->dq_sb, dquot->dq_type)->u.v2_i.i, dquot);
 }
 
-/* Free dquot entry in data block */
-static int free_dqentry(struct dquot *dquot, uint blk)
-{
-       struct super_block *sb = dquot->dq_sb;
-       int type = dquot->dq_type;
-       struct v2_disk_dqdbheader *dh;
-       dqbuf_t buf = getdqbuf();
-       int ret = 0;
-
-       if (!buf)
-               return -ENOMEM;
-       if (dquot->dq_off >> V2_DQBLKSIZE_BITS != blk) {
-               printk(KERN_ERR "VFS: Quota structure has offset to other "
-                 "block (%u) than it should (%u).\n", blk,
-                 (uint)(dquot->dq_off >> V2_DQBLKSIZE_BITS));
-               goto out_buf;
-       }
-       if ((ret = read_blk(sb, type, blk, buf)) < 0) {
-               printk(KERN_ERR "VFS: Can't read quota data block %u\n", blk);
-               goto out_buf;
-       }
-       dh = (struct v2_disk_dqdbheader *)buf;
-       le16_add_cpu(&dh->dqdh_entries, -1);
-       if (!le16_to_cpu(dh->dqdh_entries)) {   /* Block got free? */
-               if ((ret = remove_free_dqentry(sb, type, buf, blk)) < 0 ||
-                   (ret = put_free_dqblk(sb, type, buf, blk)) < 0) {
-                       printk(KERN_ERR "VFS: Can't move quota data block (%u) "
-                         "to free list.\n", blk);
-                       goto out_buf;
-               }
-       }
-       else {
-               memset(buf+(dquot->dq_off & ((1 << V2_DQBLKSIZE_BITS)-1)), 0,
-                 sizeof(struct v2_disk_dqblk));
-               if (le16_to_cpu(dh->dqdh_entries) == V2_DQSTRINBLK-1) {
-                       /* Insert will write block itself */
-                       if ((ret = insert_free_dqentry(sb, type, buf, blk)) < 0) {
-                               printk(KERN_ERR "VFS: Can't insert quota data block (%u) to free entry list.\n", blk);
-                               goto out_buf;
-                       }
-               }
-               else
-                       if ((ret = write_blk(sb, type, blk, buf)) < 0) {
-                               printk(KERN_ERR "VFS: Can't write quota data "
-                                 "block %u\n", blk);
-                               goto out_buf;
-                       }
-       }
-       dquot->dq_off = 0;      /* Quota is now unattached */
-out_buf:
-       freedqbuf(buf);
-       return ret;
-}
-
-/* Remove reference to dquot from tree */
-static int remove_tree(struct dquot *dquot, uint *blk, int depth)
-{
-       struct super_block *sb = dquot->dq_sb;
-       int type = dquot->dq_type;
-       dqbuf_t buf = getdqbuf();
-       int ret = 0;
-       uint newblk;
-       __le32 *ref = (__le32 *)buf;
-       
-       if (!buf)
-               return -ENOMEM;
-       if ((ret = read_blk(sb, type, *blk, buf)) < 0) {
-               printk(KERN_ERR "VFS: Can't read quota data block %u\n", *blk);
-               goto out_buf;
-       }
-       newblk = le32_to_cpu(ref[GETIDINDEX(dquot->dq_id, depth)]);
-       if (depth == V2_DQTREEDEPTH-1) {
-               ret = free_dqentry(dquot, newblk);
-               newblk = 0;
-       }
-       else
-               ret = remove_tree(dquot, &newblk, depth+1);
-       if (ret >= 0 && !newblk) {
-               int i;
-               ref[GETIDINDEX(dquot->dq_id, depth)] = cpu_to_le32(0);
-               for (i = 0; i < V2_DQBLKSIZE && !buf[i]; i++);  /* Block got empty? */
-               /* Don't put the root block into the free block list */
-               if (i == V2_DQBLKSIZE && *blk != V2_DQTREEOFF) {
-                       put_free_dqblk(sb, type, buf, *blk);
-                       *blk = 0;
-               }
-               else
-                       if ((ret = write_blk(sb, type, *blk, buf)) < 0)
-                               printk(KERN_ERR "VFS: Can't write quota tree "
-                                 "block %u.\n", *blk);
-       }
-out_buf:
-       freedqbuf(buf);
-       return ret;     
-}
-
-/* Delete dquot from tree */
-static int v2_delete_dquot(struct dquot *dquot)
-{
-       uint tmp = V2_DQTREEOFF;
-
-       if (!dquot->dq_off)     /* Even not allocated? */
-               return 0;
-       return remove_tree(dquot, &tmp, 0);
-}
-
-/* Find entry in block */
-static loff_t find_block_dqentry(struct dquot *dquot, uint blk)
-{
-       dqbuf_t buf = getdqbuf();
-       loff_t ret = 0;
-       int i;
-       struct v2_disk_dqblk *ddquot = GETENTRIES(buf);
-
-       if (!buf)
-               return -ENOMEM;
-       if ((ret = read_blk(dquot->dq_sb, dquot->dq_type, blk, buf)) < 0) {
-               printk(KERN_ERR "VFS: Can't read quota tree block %u.\n", blk);
-               goto out_buf;
-       }
-       if (dquot->dq_id)
-               for (i = 0; i < V2_DQSTRINBLK &&
-                    le32_to_cpu(ddquot[i].dqb_id) != dquot->dq_id; i++);
-       else {  /* ID 0 as a bit more complicated searching... */
-               struct v2_disk_dqblk fakedquot;
-
-               memset(&fakedquot, 0, sizeof(struct v2_disk_dqblk));
-               for (i = 0; i < V2_DQSTRINBLK; i++)
-                       if (!le32_to_cpu(ddquot[i].dqb_id) &&
-                           memcmp(&fakedquot, ddquot+i, sizeof(struct v2_disk_dqblk)))
-                               break;
-       }
-       if (i == V2_DQSTRINBLK) {
-               printk(KERN_ERR "VFS: Quota for id %u referenced "
-                 "but not present.\n", dquot->dq_id);
-               ret = -EIO;
-               goto out_buf;
-       }
-       else
-               ret = (blk << V2_DQBLKSIZE_BITS) + sizeof(struct
-                 v2_disk_dqdbheader) + i * sizeof(struct v2_disk_dqblk);
-out_buf:
-       freedqbuf(buf);
-       return ret;
-}
-
-/* Find entry for given id in the tree */
-static loff_t find_tree_dqentry(struct dquot *dquot, uint blk, int depth)
-{
-       dqbuf_t buf = getdqbuf();
-       loff_t ret = 0;
-       __le32 *ref = (__le32 *)buf;
-
-       if (!buf)
-               return -ENOMEM;
-       if ((ret = read_blk(dquot->dq_sb, dquot->dq_type, blk, buf)) < 0) {
-               printk(KERN_ERR "VFS: Can't read quota tree block %u.\n", blk);
-               goto out_buf;
-       }
-       ret = 0;
-       blk = le32_to_cpu(ref[GETIDINDEX(dquot->dq_id, depth)]);
-       if (!blk)       /* No reference? */
-               goto out_buf;
-       if (depth < V2_DQTREEDEPTH-1)
-               ret = find_tree_dqentry(dquot, blk, depth+1);
-       else
-               ret = find_block_dqentry(dquot, blk);
-out_buf:
-       freedqbuf(buf);
-       return ret;
-}
-
-/* Find entry for given id in the tree - wrapper function */
-static inline loff_t find_dqentry(struct dquot *dquot)
-{
-       return find_tree_dqentry(dquot, V2_DQTREEOFF, 0);
-}
-
-static int v2_read_dquot(struct dquot *dquot)
-{
-       int type = dquot->dq_type;
-       loff_t offset;
-       struct v2_disk_dqblk ddquot, empty;
-       int ret = 0;
-
-#ifdef __QUOTA_V2_PARANOIA
-       /* Invalidated quota? */
-       if (!dquot->dq_sb || !sb_dqopt(dquot->dq_sb)->files[type]) {
-               printk(KERN_ERR "VFS: Quota invalidated while reading!\n");
-               return -EIO;
-       }
-#endif
-       offset = find_dqentry(dquot);
-       if (offset <= 0) {      /* Entry not present? */
-               if (offset < 0)
-                       printk(KERN_ERR "VFS: Can't read quota "
-                         "structure for id %u.\n", 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;
-       }
-       else {
-               dquot->dq_off = offset;
-               if ((ret = dquot->dq_sb->s_op->quota_read(dquot->dq_sb, type,
-                   (char *)&ddquot, sizeof(struct v2_disk_dqblk), offset))
-                   != sizeof(struct v2_disk_dqblk)) {
-                       if (ret >= 0)
-                               ret = -EIO;
-                       printk(KERN_ERR "VFS: Error while reading quota "
-                         "structure for id %u.\n", dquot->dq_id);
-                       memset(&ddquot, 0, sizeof(struct v2_disk_dqblk));
-               }
-               else {
-                       ret = 0;
-                       /* We need to escape back all-zero structure */
-                       memset(&empty, 0, sizeof(struct v2_disk_dqblk));
-                       empty.dqb_itime = cpu_to_le64(1);
-                       if (!memcmp(&empty, &ddquot, sizeof(struct v2_disk_dqblk)))
-                               ddquot.dqb_itime = 0;
-               }
-               disk2memdqb(&dquot->dq_dqb, &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);
-       }
-       dqstats.reads++;
-
-       return ret;
-}
-
-/* Check whether dquot should not be deleted. We know we are
- * the only one operating on dquot (thanks to dq_lock) */
 static int v2_release_dquot(struct dquot *dquot)
 {
-       if (test_bit(DQ_FAKE_B, &dquot->dq_flags) && !(dquot->dq_dqb.dqb_curinodes | dquot->dq_dqb.dqb_curspace))
-               return v2_delete_dquot(dquot);
-       return 0;
+       return qtree_release_dquot(&sb_dqinfo(dquot->dq_sb, dquot->dq_type)->u.v2_i.i, dquot);
 }
 
 static struct quota_format_ops v2_format_ops = {
 
        0               /* GRPQUOTA */\
 }
 
+/* First generic header */
+struct v2_disk_dqheader {
+       __le32 dqh_magic;       /* Magic number identifying file */
+       __le32 dqh_version;     /* File version */
+};
+
 /*
  * The following structure defines the format of the disk quota file
  * (as it appears on disk) - the file is a radix tree whose leaves point
        __le64 dqb_itime;       /* time limit for excessive inode use */
 };
 
-/*
- * Here are header structures as written on disk and their in-memory copies
- */
-/* First generic header */
-struct v2_disk_dqheader {
-       __le32 dqh_magic;       /* Magic number identifying file */
-       __le32 dqh_version;     /* File version */
-};
-
 /* Header with type and version specific information */
 struct v2_disk_dqinfo {
        __le32 dqi_bgrace;      /* Time before block soft limit becomes hard limit */
        __le32 dqi_free_entry;  /* Number of block with at least one free entry */
 };
 
-/*
- *  Structure of header of block with quota structures. It is padded to 16 bytes so
- *  there will be space for exactly 21 quota-entries in a block
- */
-struct v2_disk_dqdbheader {
-       __le32 dqdh_next_free;  /* Number of next block with free entry */
-       __le32 dqdh_prev_free;  /* Number of previous block with free entry */
-       __le16 dqdh_entries;    /* Number of valid entries in block */
-       __le16 dqdh_pad1;
-       __le32 dqdh_pad2;
-};
-
 #define V2_DQINFOOFF   sizeof(struct v2_disk_dqheader) /* Offset of info header in file */
-#define V2_DQBLKSIZE_BITS      10
-#define V2_DQBLKSIZE   (1 << V2_DQBLKSIZE_BITS)        /* Size of block with quota structures */
-#define V2_DQTREEOFF   1               /* Offset of tree in file in blocks */
-#define V2_DQTREEDEPTH 4               /* Depth of quota tree */
-#define V2_DQSTRINBLK  ((V2_DQBLKSIZE - sizeof(struct v2_disk_dqdbheader)) / sizeof(struct v2_disk_dqblk))     /* Number of entries in one blocks */
+#define V2_DQBLKSIZE_BITS 10                           /* Size of leaf block in tree */
 
 #endif /* _LINUX_QUOTAIO_V2_H */
 
--- /dev/null
+/*
+ *     Definitions of structures and functions for quota formats using trie
+ */
+
+#ifndef _LINUX_DQBLK_QTREE_H
+#define _LINUX_DQBLK_QTREE_H
+
+#include <linux/types.h>
+
+/* Numbers of blocks needed for updates - we count with the smallest
+ * possible block size (1024) */
+#define QTREE_INIT_ALLOC 4
+#define QTREE_INIT_REWRITE 2
+#define QTREE_DEL_ALLOC 0
+#define QTREE_DEL_REWRITE 6
+
+struct dquot;
+
+/* Operations */
+struct qtree_fmt_operations {
+       void (*mem2disk_dqblk)(void *disk, struct dquot *dquot);        /* Convert given entry from in memory format to disk one */
+       void (*disk2mem_dqblk)(struct dquot *dquot, void *disk);        /* Convert given entry from disk format to in memory one */
+       int (*is_id)(void *disk, struct dquot *dquot);  /* Is this structure for given id? */
+};
+
+/* Inmemory copy of version specific information */
+struct qtree_mem_dqinfo {
+       struct super_block *dqi_sb;     /* Sb quota is on */
+       int dqi_type;                   /* Quota type */
+       unsigned int dqi_blocks;        /* # of blocks in quota file */
+       unsigned int dqi_free_blk;      /* First block in list of free blocks */
+       unsigned int dqi_free_entry;    /* First block with free entry */
+       unsigned int dqi_blocksize_bits;        /* Block size of quota file */
+       unsigned int dqi_entry_size;    /* Size of quota entry in quota file */
+       unsigned int dqi_usable_bs;     /* Space usable in block for quota data */
+       unsigned int dqi_qtree_depth;   /* Precomputed depth of quota tree */
+       struct qtree_fmt_operations *dqi_ops;   /* Operations for entry manipulation */
+};
+
+int qtree_write_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot);
+int qtree_read_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot);
+int qtree_delete_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot);
+int qtree_release_dquot(struct qtree_mem_dqinfo *info, struct dquot *dquot);
+int qtree_entry_unused(struct qtree_mem_dqinfo *info, char *disk);
+static inline int qtree_depth(struct qtree_mem_dqinfo *info)
+{
+       unsigned int epb = info->dqi_usable_bs >> 2;
+       unsigned long long entries = epb;
+       int i;
+
+       for (i = 1; entries < (1ULL << 32); i++)
+               entries *= epb;
+       return i;
+}
+
+#endif /* _LINUX_DQBLK_QTREE_H */
 
 /*
- *     Definitions of structures for vfsv0 quota format
+ *  Definitions for vfsv0 quota format
  */
 
 #ifndef _LINUX_DQBLK_V2_H
 #define _LINUX_DQBLK_V2_H
 
-#include <linux/types.h>
+#include <linux/dqblk_qtree.h>
 
-/* id numbers of quota format */
+/* Id number of quota format */
 #define QFMT_VFS_V0 2
 
 /* Numbers of blocks needed for updates */
-#define V2_INIT_ALLOC 4
-#define V2_INIT_REWRITE 2
-#define V2_DEL_ALLOC 0
-#define V2_DEL_REWRITE 6
+#define V2_INIT_ALLOC QTREE_INIT_ALLOC
+#define V2_INIT_REWRITE QTREE_INIT_REWRITE
+#define V2_DEL_ALLOC QTREE_DEL_ALLOC
+#define V2_DEL_REWRITE QTREE_DEL_REWRITE
 
-/* Inmemory copy of version specific information */
 struct v2_mem_dqinfo {
-       unsigned int dqi_blocks;
-       unsigned int dqi_free_blk;
-       unsigned int dqi_free_entry;
+       struct qtree_mem_dqinfo i;
 };
 
 #endif /* _LINUX_DQBLK_V2_H */