quota: Move quota files into separate directory

Quota subsystem has more and more files. It's time to create a dir for it.

Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 645 insertions, 0 deletions

diff --git a/fs/quota/quota_tree.c b/fs/quota/quota_tree.c
new file mode 100644
index 000000000000..953404c95b17
--- /dev/null
+++ b/fs/quota/quota_tree.c
@@ -0,0 +1,645 @@
+/*
+ *      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);