ocfs2: Implementation of local and global quota file handling

For each quota type each node has local quota file. In this file it stores
changes users have made to disk usage via this node. Once in a while this
information is synced to global file (and thus with other nodes) so that
limits enforcement at least aproximately works.

Global quota files contain all the information about usage and limits. It's
mostly handled by the generic VFS code (which implements a trie of structures
inside a quota file). We only have to provide functions to convert structures
from on-disk format to in-memory one. We also have to provide wrappers for
various quota functions starting transactions and acquiring necessary cluster
locks before the actual IO is really started.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

1 files changed, 833 insertions, 0 deletions

diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
new file mode 100644
index 000000000000..55c3f2f98dcd
--- /dev/null
+++ b/fs/ocfs2/quota_local.c
@@ -0,0 +1,833 @@
+/*
+ *  Implementation of operations over local quota file
+ */
+
+#include <linux/fs.h>
+#include <linux/quota.h>
+#include <linux/quotaops.h>
+#include <linux/module.h>
+
+#define MLOG_MASK_PREFIX ML_QUOTA
+#include <cluster/masklog.h>
+
+#include "ocfs2_fs.h"
+#include "ocfs2.h"
+#include "inode.h"
+#include "alloc.h"
+#include "file.h"
+#include "buffer_head_io.h"
+#include "journal.h"
+#include "sysfile.h"
+#include "dlmglue.h"
+#include "quota.h"
+
+/* Number of local quota structures per block */
+static inline unsigned int ol_quota_entries_per_block(struct super_block *sb)
+{
+        return ((sb->s_blocksize - OCFS2_QBLK_RESERVED_SPACE) /
+                sizeof(struct ocfs2_local_disk_dqblk));
+}
+
+/* Number of blocks with entries in one chunk */
+static inline unsigned int ol_chunk_blocks(struct super_block *sb)
+{
+        return ((sb->s_blocksize - sizeof(struct ocfs2_local_disk_chunk) -
+                 OCFS2_QBLK_RESERVED_SPACE) << 3) /
+               ol_quota_entries_per_block(sb);
+}
+
+/* Number of entries in a chunk bitmap */
+static unsigned int ol_chunk_entries(struct super_block *sb)
+{
+        return ol_chunk_blocks(sb) * ol_quota_entries_per_block(sb);
+}
+
+/* Offset of the chunk in quota file */
+static unsigned int ol_quota_chunk_block(struct super_block *sb, int c)
+{
+        /* 1 block for local quota file info, 1 block per chunk for chunk info */
+        return 1 + (ol_chunk_blocks(sb) + 1) * c;
+}
+
+/* Offset of the dquot structure in the quota file */
+static loff_t ol_dqblk_off(struct super_block *sb, int c, int off)
+{
+        int epb = ol_quota_entries_per_block(sb);
+
+        return ((ol_quota_chunk_block(sb, c) + 1 + off / epb)
+                << sb->s_blocksize_bits) +
+                (off % epb) * sizeof(struct ocfs2_local_disk_dqblk);
+}
+
+/* Compute block number from given offset */
+static inline unsigned int ol_dqblk_file_block(struct super_block *sb, loff_t off)
+{
+        return off >> sb->s_blocksize_bits;
+}
+
+static inline unsigned int ol_dqblk_block_offset(struct super_block *sb, loff_t off)
+{
+        return off & ((1 << sb->s_blocksize_bits) - 1);
+}
+
+/* Compute offset in the chunk of a structure with the given offset */
+static int ol_dqblk_chunk_off(struct super_block *sb, int c, loff_t off)
+{
+        int epb = ol_quota_entries_per_block(sb);
+
+        return ((off >> sb->s_blocksize_bits) -
+                        ol_quota_chunk_block(sb, c) - 1) * epb
+               + ((unsigned int)(off & ((1 << sb->s_blocksize_bits) - 1))) /
+                 sizeof(struct ocfs2_local_disk_dqblk);
+}
+
+/* Write bufferhead into the fs */
+static int ocfs2_modify_bh(struct inode *inode, struct buffer_head *bh,
+                void (*modify)(struct buffer_head *, void *), void *private)
+{
+        struct super_block *sb = inode->i_sb;
+        handle_t *handle;
+        int status;
+
+        handle = ocfs2_start_trans(OCFS2_SB(sb), 1);
+        if (IS_ERR(handle)) {
+                status = PTR_ERR(handle);
+                mlog_errno(status);
+                return status;
+        }
+        status = ocfs2_journal_access(handle, inode, bh,
+                                      OCFS2_JOURNAL_ACCESS_WRITE);
+        if (status < 0) {
+                mlog_errno(status);
+                ocfs2_commit_trans(OCFS2_SB(sb), handle);
+                return status;
+        }
+        lock_buffer(bh);
+        modify(bh, private);
+        unlock_buffer(bh);
+        status = ocfs2_journal_dirty(handle, bh);
+        if (status < 0) {
+                mlog_errno(status);
+                ocfs2_commit_trans(OCFS2_SB(sb), handle);
+                return status;
+        }
+        status = ocfs2_commit_trans(OCFS2_SB(sb), handle);
+        if (status < 0) {
+                mlog_errno(status);
+                return status;
+        }
+        return 0;
+}
+
+/* Check whether we understand format of quota files */
+static int ocfs2_local_check_quota_file(struct super_block *sb, int type)
+{
+        unsigned int lmagics[MAXQUOTAS] = OCFS2_LOCAL_QMAGICS;
+        unsigned int lversions[MAXQUOTAS] = OCFS2_LOCAL_QVERSIONS;
+        unsigned int gmagics[MAXQUOTAS] = OCFS2_GLOBAL_QMAGICS;
+        unsigned int gversions[MAXQUOTAS] = OCFS2_GLOBAL_QVERSIONS;
+        unsigned int ino[MAXQUOTAS] = { USER_QUOTA_SYSTEM_INODE,
+                                        GROUP_QUOTA_SYSTEM_INODE };
+        struct buffer_head *bh;
+        struct inode *linode = sb_dqopt(sb)->files[type];
+        struct inode *ginode = NULL;
+        struct ocfs2_disk_dqheader *dqhead;
+        int status, ret = 0;
+
+        /* First check whether we understand local quota file */
+        bh = ocfs2_read_quota_block(linode, 0, &status);
+        if (!bh) {
+                mlog_errno(status);
+                mlog(ML_ERROR, "failed to read quota file header (type=%d)\n",
+                        type);
+                goto out_err;
+        }
+        dqhead = (struct ocfs2_disk_dqheader *)(bh->b_data);
+        if (le32_to_cpu(dqhead->dqh_magic) != lmagics[type]) {
+                mlog(ML_ERROR, "quota file magic does not match (%u != %u),"
+                        " type=%d\n", le32_to_cpu(dqhead->dqh_magic),
+                        lmagics[type], type);
+                goto out_err;
+        }
+        if (le32_to_cpu(dqhead->dqh_version) != lversions[type]) {
+                mlog(ML_ERROR, "quota file version does not match (%u != %u),"
+                        " type=%d\n", le32_to_cpu(dqhead->dqh_version),
+                        lversions[type], type);
+                goto out_err;
+        }
+        brelse(bh);
+        bh = NULL;
+
+        /* Next check whether we understand global quota file */
+        ginode = ocfs2_get_system_file_inode(OCFS2_SB(sb), ino[type],
+                                                OCFS2_INVALID_SLOT);
+        if (!ginode) {
+                mlog(ML_ERROR, "cannot get global quota file inode "
+                                "(type=%d)\n", type);
+                goto out_err;
+        }
+        /* Since the header is read only, we don't care about locking */
+        bh = ocfs2_read_quota_block(ginode, 0, &status);
+        if (!bh) {
+                mlog_errno(status);
+                mlog(ML_ERROR, "failed to read global quota file header "
+                                "(type=%d)\n", type);
+                goto out_err;
+        }
+        dqhead = (struct ocfs2_disk_dqheader *)(bh->b_data);
+        if (le32_to_cpu(dqhead->dqh_magic) != gmagics[type]) {
+                mlog(ML_ERROR, "global quota file magic does not match "
+                        "(%u != %u), type=%d\n",
+                        le32_to_cpu(dqhead->dqh_magic), gmagics[type], type);
+                goto out_err;
+        }
+        if (le32_to_cpu(dqhead->dqh_version) != gversions[type]) {
+                mlog(ML_ERROR, "global quota file version does not match "
+                        "(%u != %u), type=%d\n",
+                        le32_to_cpu(dqhead->dqh_version), gversions[type],
+                        type);
+                goto out_err;
+        }
+
+        ret = 1;
+out_err:
+        brelse(bh);
+        iput(ginode);
+        return ret;
+}
+
+/* Release given list of quota file chunks */
+static void ocfs2_release_local_quota_bitmaps(struct list_head *head)
+{
+        struct ocfs2_quota_chunk *pos, *next;
+
+        list_for_each_entry_safe(pos, next, head, qc_chunk) {
+                list_del(&pos->qc_chunk);
+                brelse(pos->qc_headerbh);
+                kmem_cache_free(ocfs2_qf_chunk_cachep, pos);
+        }
+}
+
+/* Load quota bitmaps into memory */
+static int ocfs2_load_local_quota_bitmaps(struct inode *inode,
+                        struct ocfs2_local_disk_dqinfo *ldinfo,
+                        struct list_head *head)
+{
+        struct ocfs2_quota_chunk *newchunk;
+        int i, status;
+
+        INIT_LIST_HEAD(head);
+        for (i = 0; i < le32_to_cpu(ldinfo->dqi_chunks); i++) {
+                newchunk = kmem_cache_alloc(ocfs2_qf_chunk_cachep, GFP_NOFS);
+                if (!newchunk) {
+                        ocfs2_release_local_quota_bitmaps(head);
+                        return -ENOMEM;
+                }
+                newchunk->qc_num = i;
+                newchunk->qc_headerbh = ocfs2_read_quota_block(inode,
+                                ol_quota_chunk_block(inode->i_sb, i),
+                                &status);
+                if (!newchunk->qc_headerbh) {
+                        mlog_errno(status);
+                        kmem_cache_free(ocfs2_qf_chunk_cachep, newchunk);
+                        ocfs2_release_local_quota_bitmaps(head);
+                        return status;
+                }
+                list_add_tail(&newchunk->qc_chunk, head);
+        }
+        return 0;
+}
+
+static void olq_update_info(struct buffer_head *bh, void *private)
+{
+        struct mem_dqinfo *info = private;
+        struct ocfs2_mem_dqinfo *oinfo = info->dqi_priv;
+        struct ocfs2_local_disk_dqinfo *ldinfo;
+
+        ldinfo = (struct ocfs2_local_disk_dqinfo *)(bh->b_data +
+                                                OCFS2_LOCAL_INFO_OFF);
+        spin_lock(&dq_data_lock);
+        ldinfo->dqi_flags = cpu_to_le32(info->dqi_flags & DQF_MASK);
+        ldinfo->dqi_chunks = cpu_to_le32(oinfo->dqi_chunks);
+        ldinfo->dqi_blocks = cpu_to_le32(oinfo->dqi_blocks);
+        spin_unlock(&dq_data_lock);
+}
+
+/* Read information header from quota file */
+static int ocfs2_local_read_info(struct super_block *sb, int type)
+{
+        struct ocfs2_local_disk_dqinfo *ldinfo;
+        struct mem_dqinfo *info = sb_dqinfo(sb, type);
+        struct ocfs2_mem_dqinfo *oinfo;
+        struct inode *lqinode = sb_dqopt(sb)->files[type];
+        int status;
+        struct buffer_head *bh = NULL;
+        int locked = 0;
+
+        info->dqi_maxblimit = 0x7fffffffffffffffLL;
+        info->dqi_maxilimit = 0x7fffffffffffffffLL;
+        oinfo = kmalloc(sizeof(struct ocfs2_mem_dqinfo), GFP_NOFS);
+        if (!oinfo) {
+                mlog(ML_ERROR, "failed to allocate memory for ocfs2 quota"
+                               " info.");
+                goto out_err;
+        }
+        info->dqi_priv = oinfo;
+        oinfo->dqi_type = type;
+        INIT_LIST_HEAD(&oinfo->dqi_chunk);
+        oinfo->dqi_lqi_bh = NULL;
+        oinfo->dqi_ibh = NULL;
+
+        status = ocfs2_global_read_info(sb, type);
+        if (status < 0)
+                goto out_err;
+
+        status = ocfs2_inode_lock(lqinode, &oinfo->dqi_lqi_bh, 1);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out_err;
+        }
+        locked = 1;
+
+        /* Now read local header */
+        bh = ocfs2_read_quota_block(lqinode, 0, &status);
+        if (!bh) {
+                mlog_errno(status);
+                mlog(ML_ERROR, "failed to read quota file info header "
+                        "(type=%d)\n", type);
+                goto out_err;
+        }
+        ldinfo = (struct ocfs2_local_disk_dqinfo *)(bh->b_data +
+                                                OCFS2_LOCAL_INFO_OFF);
+        info->dqi_flags = le32_to_cpu(ldinfo->dqi_flags);
+        oinfo->dqi_chunks = le32_to_cpu(ldinfo->dqi_chunks);
+        oinfo->dqi_blocks = le32_to_cpu(ldinfo->dqi_blocks);
+        oinfo->dqi_ibh = bh;
+
+        /* We crashed when using local quota file? */
+        if (!(info->dqi_flags & OLQF_CLEAN))
+                goto out_err;   /* So far we just bail out. Later we should resync here */
+
+        status = ocfs2_load_local_quota_bitmaps(sb_dqopt(sb)->files[type],
+                                                ldinfo,
+                                                &oinfo->dqi_chunk);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out_err;
+        }
+
+        /* Now mark quota file as used */
+        info->dqi_flags &= ~OLQF_CLEAN;
+        status = ocfs2_modify_bh(lqinode, bh, olq_update_info, info);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out_err;
+        }
+
+        return 0;
+out_err:
+        if (oinfo) {
+                iput(oinfo->dqi_gqinode);
+                ocfs2_simple_drop_lockres(OCFS2_SB(sb), &oinfo->dqi_gqlock);
+                ocfs2_lock_res_free(&oinfo->dqi_gqlock);
+                brelse(oinfo->dqi_lqi_bh);
+                if (locked)
+                        ocfs2_inode_unlock(lqinode, 1);
+                ocfs2_release_local_quota_bitmaps(&oinfo->dqi_chunk);
+                kfree(oinfo);
+        }
+        brelse(bh);
+        return -1;
+}
+
+/* Write local info to quota file */
+static int ocfs2_local_write_info(struct super_block *sb, int type)
+{
+        struct mem_dqinfo *info = sb_dqinfo(sb, type);
+        struct buffer_head *bh = ((struct ocfs2_mem_dqinfo *)info->dqi_priv)
+                                                ->dqi_ibh;
+        int status;
+
+        status = ocfs2_modify_bh(sb_dqopt(sb)->files[type], bh, olq_update_info,
+                                 info);
+        if (status < 0) {
+                mlog_errno(status);
+                return -1;
+        }
+
+        return 0;
+}
+
+/* Release info from memory */
+static int ocfs2_local_free_info(struct super_block *sb, int type)
+{
+        struct mem_dqinfo *info = sb_dqinfo(sb, type);
+        struct ocfs2_mem_dqinfo *oinfo = info->dqi_priv;
+        struct ocfs2_quota_chunk *chunk;
+        struct ocfs2_local_disk_chunk *dchunk;
+        int mark_clean = 1, len;
+        int status;
+
+        iput(oinfo->dqi_gqinode);
+        ocfs2_simple_drop_lockres(OCFS2_SB(sb), &oinfo->dqi_gqlock);
+        ocfs2_lock_res_free(&oinfo->dqi_gqlock);
+        list_for_each_entry(chunk, &oinfo->dqi_chunk, qc_chunk) {
+                dchunk = (struct ocfs2_local_disk_chunk *)
+                                        (chunk->qc_headerbh->b_data);
+                if (chunk->qc_num < oinfo->dqi_chunks - 1) {
+                        len = ol_chunk_entries(sb);
+                } else {
+                        len = (oinfo->dqi_blocks -
+                               ol_quota_chunk_block(sb, chunk->qc_num) - 1)
+                              * ol_quota_entries_per_block(sb);
+                }
+                /* Not all entries free? Bug! */
+                if (le32_to_cpu(dchunk->dqc_free) != len) {
+                        mlog(ML_ERROR, "releasing quota file with used "
+                                        "entries (type=%d)\n", type);
+                        mark_clean = 0;
+                }
+        }
+        ocfs2_release_local_quota_bitmaps(&oinfo->dqi_chunk);
+
+        if (!mark_clean)
+                goto out;
+
+        /* Mark local file as clean */
+        info->dqi_flags |= OLQF_CLEAN;
+        status = ocfs2_modify_bh(sb_dqopt(sb)->files[type],
+                                 oinfo->dqi_ibh,
+                                 olq_update_info,
+                                 info);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out;
+        }
+
+out:
+        ocfs2_inode_unlock(sb_dqopt(sb)->files[type], 1);
+        brelse(oinfo->dqi_ibh);
+        brelse(oinfo->dqi_lqi_bh);
+        kfree(oinfo);
+        return 0;
+}
+
+static void olq_set_dquot(struct buffer_head *bh, void *private)
+{
+        struct ocfs2_dquot *od = private;
+        struct ocfs2_local_disk_dqblk *dqblk;
+        struct super_block *sb = od->dq_dquot.dq_sb;
+
+        dqblk = (struct ocfs2_local_disk_dqblk *)(bh->b_data
+                + ol_dqblk_block_offset(sb, od->dq_local_off));
+
+        dqblk->dqb_id = cpu_to_le64(od->dq_dquot.dq_id);
+        spin_lock(&dq_data_lock);
+        dqblk->dqb_spacemod = cpu_to_le64(od->dq_dquot.dq_dqb.dqb_curspace -
+                                          od->dq_origspace);
+        dqblk->dqb_inodemod = cpu_to_le64(od->dq_dquot.dq_dqb.dqb_curinodes -
+                                          od->dq_originodes);
+        spin_unlock(&dq_data_lock);
+        mlog(0, "Writing local dquot %u space %lld inodes %lld\n",
+             od->dq_dquot.dq_id, dqblk->dqb_spacemod, dqblk->dqb_inodemod);
+}
+
+/* Write dquot to local quota file */
+static int ocfs2_local_write_dquot(struct dquot *dquot)
+{
+        struct super_block *sb = dquot->dq_sb;
+        struct ocfs2_dquot *od = OCFS2_DQUOT(dquot);
+        struct buffer_head *bh;
+        int status;
+
+        bh = ocfs2_read_quota_block(sb_dqopt(sb)->files[dquot->dq_type],
+                                    ol_dqblk_file_block(sb, od->dq_local_off),
+                                    &status);
+        if (!bh) {
+                mlog_errno(status);
+                goto out;
+        }
+        status = ocfs2_modify_bh(sb_dqopt(sb)->files[dquot->dq_type], bh,
+                                 olq_set_dquot, od);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out;
+        }
+out:
+        brelse(bh);
+        return status;
+}
+
+/* Find free entry in local quota file */
+static struct ocfs2_quota_chunk *ocfs2_find_free_entry(struct super_block *sb,
+                                                       int type,
+                                                       int *offset)
+{
+        struct mem_dqinfo *info = sb_dqinfo(sb, type);
+        struct ocfs2_mem_dqinfo *oinfo = info->dqi_priv;
+        struct ocfs2_quota_chunk *chunk;
+        struct ocfs2_local_disk_chunk *dchunk;
+        int found = 0, len;
+
+        list_for_each_entry(chunk, &oinfo->dqi_chunk, qc_chunk) {
+                dchunk = (struct ocfs2_local_disk_chunk *)
+                                                chunk->qc_headerbh->b_data;
+                if (le32_to_cpu(dchunk->dqc_free) > 0) {
+                        found = 1;
+                        break;
+                }
+        }
+        if (!found)
+                return NULL;
+
+        if (chunk->qc_num < oinfo->dqi_chunks - 1) {
+                len = ol_chunk_entries(sb);
+        } else {
+                len = (oinfo->dqi_blocks -
+                       ol_quota_chunk_block(sb, chunk->qc_num) - 1)
+                      * ol_quota_entries_per_block(sb);
+        }
+
+        found = ocfs2_find_next_zero_bit(dchunk->dqc_bitmap, len, 0);
+        /* We failed? */
+        if (found == len) {
+                mlog(ML_ERROR, "Did not find empty entry in chunk %d with %u"
+                     " entries free (type=%d)\n", chunk->qc_num,
+                     le32_to_cpu(dchunk->dqc_free), type);
+                return ERR_PTR(-EIO);
+        }
+        *offset = found;
+        return chunk;
+}
+
+/* Add new chunk to the local quota file */
+static struct ocfs2_quota_chunk *ocfs2_local_quota_add_chunk(
+                                                        struct super_block *sb,
+                                                        int type,
+                                                        int *offset)
+{
+        struct mem_dqinfo *info = sb_dqinfo(sb, type);
+        struct ocfs2_mem_dqinfo *oinfo = info->dqi_priv;
+        struct inode *lqinode = sb_dqopt(sb)->files[type];
+        struct ocfs2_quota_chunk *chunk = NULL;
+        struct ocfs2_local_disk_chunk *dchunk;
+        int status;
+        handle_t *handle;
+        struct buffer_head *bh = NULL;
+        u64 p_blkno;
+
+        /* We are protected by dqio_sem so no locking needed */
+        status = ocfs2_extend_no_holes(lqinode,
+                                       lqinode->i_size + 2 * sb->s_blocksize,
+                                       lqinode->i_size);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out;
+        }
+        status = ocfs2_simple_size_update(lqinode, oinfo->dqi_lqi_bh,
+                                          lqinode->i_size + 2 * sb->s_blocksize);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out;
+        }
+
+        chunk = kmem_cache_alloc(ocfs2_qf_chunk_cachep, GFP_NOFS);
+        if (!chunk) {
+                status = -ENOMEM;
+                mlog_errno(status);
+                goto out;
+        }
+
+        down_read(&OCFS2_I(lqinode)->ip_alloc_sem);
+        status = ocfs2_extent_map_get_blocks(lqinode, oinfo->dqi_blocks,
+                                             &p_blkno, NULL, NULL);
+        up_read(&OCFS2_I(lqinode)->ip_alloc_sem);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out;
+        }
+        bh = sb_getblk(sb, p_blkno);
+        if (!bh) {
+                status = -ENOMEM;
+                mlog_errno(status);
+                goto out;
+        }
+        dchunk = (struct ocfs2_local_disk_chunk *)bh->b_data;
+
+        handle = ocfs2_start_trans(OCFS2_SB(sb), 2);
+        if (IS_ERR(handle)) {
+                status = PTR_ERR(handle);
+                mlog_errno(status);
+                goto out;
+        }
+
+        status = ocfs2_journal_access(handle, lqinode, bh,
+                                      OCFS2_JOURNAL_ACCESS_WRITE);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out_trans;
+        }
+        lock_buffer(bh);
+        dchunk->dqc_free = ol_quota_entries_per_block(sb);
+        memset(dchunk->dqc_bitmap, 0,
+               sb->s_blocksize - sizeof(struct ocfs2_local_disk_chunk) -
+               OCFS2_QBLK_RESERVED_SPACE);
+        set_buffer_uptodate(bh);
+        unlock_buffer(bh);
+        status = ocfs2_journal_dirty(handle, bh);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out_trans;
+        }
+
+        oinfo->dqi_blocks += 2;
+        oinfo->dqi_chunks++;
+        status = ocfs2_local_write_info(sb, type);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out_trans;
+        }
+        status = ocfs2_commit_trans(OCFS2_SB(sb), handle);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out;
+        }
+
+        list_add_tail(&chunk->qc_chunk, &oinfo->dqi_chunk);
+        chunk->qc_num = list_entry(chunk->qc_chunk.prev,
+                                   struct ocfs2_quota_chunk,
+                                   qc_chunk)->qc_num + 1;
+        chunk->qc_headerbh = bh;
+        *offset = 0;
+        return chunk;
+out_trans:
+        ocfs2_commit_trans(OCFS2_SB(sb), handle);
+out:
+        brelse(bh);
+        kmem_cache_free(ocfs2_qf_chunk_cachep, chunk);
+        return ERR_PTR(status);
+}
+
+/* Find free entry in local quota file */
+static struct ocfs2_quota_chunk *ocfs2_extend_local_quota_file(
+                                                       struct super_block *sb,
+                                                       int type,
+                                                       int *offset)
+{
+        struct mem_dqinfo *info = sb_dqinfo(sb, type);
+        struct ocfs2_mem_dqinfo *oinfo = info->dqi_priv;
+        struct ocfs2_quota_chunk *chunk;
+        struct inode *lqinode = sb_dqopt(sb)->files[type];
+        struct ocfs2_local_disk_chunk *dchunk;
+        int epb = ol_quota_entries_per_block(sb);
+        unsigned int chunk_blocks;
+        int status;
+        handle_t *handle;
+
+        if (list_empty(&oinfo->dqi_chunk))
+                return ocfs2_local_quota_add_chunk(sb, type, offset);
+        /* Is the last chunk full? */
+        chunk = list_entry(oinfo->dqi_chunk.prev,
+                        struct ocfs2_quota_chunk, qc_chunk);
+        chunk_blocks = oinfo->dqi_blocks -
+                        ol_quota_chunk_block(sb, chunk->qc_num) - 1;
+        if (ol_chunk_blocks(sb) == chunk_blocks)
+                return ocfs2_local_quota_add_chunk(sb, type, offset);
+
+        /* We are protected by dqio_sem so no locking needed */
+        status = ocfs2_extend_no_holes(lqinode,
+                                       lqinode->i_size + sb->s_blocksize,
+                                       lqinode->i_size);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out;
+        }
+        status = ocfs2_simple_size_update(lqinode, oinfo->dqi_lqi_bh,
+                                          lqinode->i_size + sb->s_blocksize);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out;
+        }
+        handle = ocfs2_start_trans(OCFS2_SB(sb), 2);
+        if (IS_ERR(handle)) {
+                status = PTR_ERR(handle);
+                mlog_errno(status);
+                goto out;
+        }
+        status = ocfs2_journal_access(handle, lqinode, chunk->qc_headerbh,
+                                 OCFS2_JOURNAL_ACCESS_WRITE);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out_trans;
+        }
+
+        dchunk = (struct ocfs2_local_disk_chunk *)chunk->qc_headerbh->b_data;
+        lock_buffer(chunk->qc_headerbh);
+        le32_add_cpu(&dchunk->dqc_free, ol_quota_entries_per_block(sb));
+        unlock_buffer(chunk->qc_headerbh);
+        status = ocfs2_journal_dirty(handle, chunk->qc_headerbh);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out_trans;
+        }
+        oinfo->dqi_blocks++;
+        status = ocfs2_local_write_info(sb, type);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out_trans;
+        }
+
+        status = ocfs2_commit_trans(OCFS2_SB(sb), handle);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out;
+        }
+        *offset = chunk_blocks * epb;
+        return chunk;
+out_trans:
+        ocfs2_commit_trans(OCFS2_SB(sb), handle);
+out:
+        return ERR_PTR(status);
+}
+
+void olq_alloc_dquot(struct buffer_head *bh, void *private)
+{
+        int *offset = private;
+        struct ocfs2_local_disk_chunk *dchunk;
+
+        dchunk = (struct ocfs2_local_disk_chunk *)bh->b_data;
+        ocfs2_set_bit(*offset, dchunk->dqc_bitmap);
+        le32_add_cpu(&dchunk->dqc_free, -1);
+}
+
+/* Create dquot in the local file for given id */
+static int ocfs2_create_local_dquot(struct dquot *dquot)
+{
+        struct super_block *sb = dquot->dq_sb;
+        int type = dquot->dq_type;
+        struct inode *lqinode = sb_dqopt(sb)->files[type];
+        struct ocfs2_quota_chunk *chunk;
+        struct ocfs2_dquot *od = OCFS2_DQUOT(dquot);
+        int offset;
+        int status;
+
+        chunk = ocfs2_find_free_entry(sb, type, &offset);
+        if (!chunk) {
+                chunk = ocfs2_extend_local_quota_file(sb, type, &offset);
+                if (IS_ERR(chunk))
+                        return PTR_ERR(chunk);
+        } else if (IS_ERR(chunk)) {
+                return PTR_ERR(chunk);
+        }
+        od->dq_local_off = ol_dqblk_off(sb, chunk->qc_num, offset);
+        od->dq_chunk = chunk;
+
+        /* Initialize dquot structure on disk */
+        status = ocfs2_local_write_dquot(dquot);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out;
+        }
+
+        /* Mark structure as allocated */
+        status = ocfs2_modify_bh(lqinode, chunk->qc_headerbh, olq_alloc_dquot,
+                                 &offset);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out;
+        }
+out:
+        return status;
+}
+
+/* Create entry in local file for dquot, load data from the global file */
+static int ocfs2_local_read_dquot(struct dquot *dquot)
+{
+        int status;
+
+        mlog_entry("id=%u, type=%d\n", dquot->dq_id, dquot->dq_type);
+
+        status = ocfs2_global_read_dquot(dquot);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out_err;
+        }
+
+        /* Now create entry in the local quota file */
+        status = ocfs2_create_local_dquot(dquot);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out_err;
+        }
+        mlog_exit(0);
+        return 0;
+out_err:
+        mlog_exit(status);
+        return status;
+}
+
+/* Release dquot structure from local quota file. ocfs2_release_dquot() has
+ * already started a transaction and obtained exclusive lock for global
+ * quota file. */
+static int ocfs2_local_release_dquot(struct dquot *dquot)
+{
+        int status;
+        int type = dquot->dq_type;
+        struct ocfs2_dquot *od = OCFS2_DQUOT(dquot);
+        struct super_block *sb = dquot->dq_sb;
+        struct ocfs2_local_disk_chunk *dchunk;
+        int offset;
+        handle_t *handle = journal_current_handle();
+
+        BUG_ON(!handle);
+        /* First write all local changes to global file */
+        status = ocfs2_global_release_dquot(dquot);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out;
+        }
+
+        status = ocfs2_journal_access(handle, sb_dqopt(sb)->files[type],
+                        od->dq_chunk->qc_headerbh, OCFS2_JOURNAL_ACCESS_WRITE);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out;
+        }
+        offset = ol_dqblk_chunk_off(sb, od->dq_chunk->qc_num,
+                                             od->dq_local_off);
+        dchunk = (struct ocfs2_local_disk_chunk *)
+                        (od->dq_chunk->qc_headerbh->b_data);
+        /* Mark structure as freed */
+        lock_buffer(od->dq_chunk->qc_headerbh);
+        ocfs2_clear_bit(offset, dchunk->dqc_bitmap);
+        le32_add_cpu(&dchunk->dqc_free, 1);
+        unlock_buffer(od->dq_chunk->qc_headerbh);
+        status = ocfs2_journal_dirty(handle, od->dq_chunk->qc_headerbh);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out;
+        }
+        status = 0;
+out:
+        /* Clear the read bit so that next time someone uses this
+         * dquot he reads fresh info from disk and allocates local
+         * dquot structure */
+        clear_bit(DQ_READ_B, &dquot->dq_flags);
+        return status;
+}
+
+static struct quota_format_ops ocfs2_format_ops = {
+        .check_quota_file       = ocfs2_local_check_quota_file,
+        .read_file_info         = ocfs2_local_read_info,
+        .write_file_info        = ocfs2_global_write_info,
+        .free_file_info         = ocfs2_local_free_info,
+        .read_dqblk             = ocfs2_local_read_dquot,
+        .commit_dqblk           = ocfs2_local_write_dquot,
+        .release_dqblk          = ocfs2_local_release_dquot,
+};
+
+struct quota_format_type ocfs2_quota_format = {
+        .qf_fmt_id = QFMT_OCFS2,
+        .qf_ops = &ocfs2_format_ops,
+        .qf_owner = THIS_MODULE
+};