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![Jan Kara](/assets/img/avatar_default.png)
Eric has reported that since commitd2faa41516
"quota: Do not acquire dqio_sem for dquot overwrites in v2 format" test generic/232 occasionally fails due to quota information being incorrect. Indeed that commit was too eager to remove dqio_sem completely from the path that just overwrites quota structure with updated information. Although that is innocent on its own, another process that inserts new quota structure to the same block can perform read-modify-write cycle of that block thus effectively discarding quota information update if they race in a wrong way. Fix the problem by acquiring dqio_sem for reading for overwrites of quota structure. Note that it *is* possible to completely avoid taking dqio_sem in the overwrite path however that will require modifying path inserting / deleting quota structures to avoid RMW cycles of the full block and for now it is not clear whether it is worth the hassle. Fixes:d2faa41516
Reported-and-tested-by: Eric Whitney <enwlinux@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz>
413 lines
12 KiB
C
413 lines
12 KiB
C
/*
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* vfsv0 quota IO operations on file
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*/
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/mount.h>
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#include <linux/dqblk_v2.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/quotaops.h>
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#include <asm/byteorder.h>
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#include "quota_tree.h"
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#include "quotaio_v2.h"
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MODULE_AUTHOR("Jan Kara");
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MODULE_DESCRIPTION("Quota format v2 support");
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MODULE_LICENSE("GPL");
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#define __QUOTA_V2_PARANOIA
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static void v2r0_mem2diskdqb(void *dp, struct dquot *dquot);
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static void v2r0_disk2memdqb(struct dquot *dquot, void *dp);
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static int v2r0_is_id(void *dp, struct dquot *dquot);
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static void v2r1_mem2diskdqb(void *dp, struct dquot *dquot);
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static void v2r1_disk2memdqb(struct dquot *dquot, void *dp);
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static int v2r1_is_id(void *dp, struct dquot *dquot);
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static const struct qtree_fmt_operations v2r0_qtree_ops = {
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.mem2disk_dqblk = v2r0_mem2diskdqb,
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.disk2mem_dqblk = v2r0_disk2memdqb,
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.is_id = v2r0_is_id,
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};
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static const struct qtree_fmt_operations v2r1_qtree_ops = {
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.mem2disk_dqblk = v2r1_mem2diskdqb,
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.disk2mem_dqblk = v2r1_disk2memdqb,
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.is_id = v2r1_is_id,
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};
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#define QUOTABLOCK_BITS 10
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#define QUOTABLOCK_SIZE (1 << QUOTABLOCK_BITS)
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static inline qsize_t v2_stoqb(qsize_t space)
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{
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return (space + QUOTABLOCK_SIZE - 1) >> QUOTABLOCK_BITS;
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}
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static inline qsize_t v2_qbtos(qsize_t blocks)
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{
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return blocks << QUOTABLOCK_BITS;
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}
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static int v2_read_header(struct super_block *sb, int type,
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struct v2_disk_dqheader *dqhead)
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{
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ssize_t size;
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size = sb->s_op->quota_read(sb, type, (char *)dqhead,
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sizeof(struct v2_disk_dqheader), 0);
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if (size != sizeof(struct v2_disk_dqheader)) {
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quota_error(sb, "Failed header read: expected=%zd got=%zd",
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sizeof(struct v2_disk_dqheader), size);
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if (size < 0)
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return size;
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return -EIO;
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}
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return 0;
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}
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/* Check whether given file is really vfsv0 quotafile */
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static int v2_check_quota_file(struct super_block *sb, int type)
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{
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struct v2_disk_dqheader dqhead;
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static const uint quota_magics[] = V2_INITQMAGICS;
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static const uint quota_versions[] = V2_INITQVERSIONS;
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if (v2_read_header(sb, type, &dqhead))
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return 0;
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if (le32_to_cpu(dqhead.dqh_magic) != quota_magics[type] ||
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le32_to_cpu(dqhead.dqh_version) > quota_versions[type])
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return 0;
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return 1;
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}
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/* Read information header from quota file */
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static int v2_read_file_info(struct super_block *sb, int type)
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{
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struct v2_disk_dqinfo dinfo;
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struct v2_disk_dqheader dqhead;
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struct quota_info *dqopt = sb_dqopt(sb);
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struct mem_dqinfo *info = &dqopt->info[type];
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struct qtree_mem_dqinfo *qinfo;
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ssize_t size;
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unsigned int version;
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int ret;
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down_read(&dqopt->dqio_sem);
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ret = v2_read_header(sb, type, &dqhead);
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if (ret < 0)
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goto out;
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version = le32_to_cpu(dqhead.dqh_version);
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if ((info->dqi_fmt_id == QFMT_VFS_V0 && version != 0) ||
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(info->dqi_fmt_id == QFMT_VFS_V1 && version != 1)) {
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ret = -EINVAL;
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goto out;
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}
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size = sb->s_op->quota_read(sb, type, (char *)&dinfo,
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sizeof(struct v2_disk_dqinfo), V2_DQINFOOFF);
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if (size != sizeof(struct v2_disk_dqinfo)) {
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quota_error(sb, "Can't read info structure");
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if (size < 0)
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ret = size;
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else
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ret = -EIO;
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goto out;
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}
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info->dqi_priv = kmalloc(sizeof(struct qtree_mem_dqinfo), GFP_NOFS);
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if (!info->dqi_priv) {
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ret = -ENOMEM;
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goto out;
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}
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qinfo = info->dqi_priv;
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if (version == 0) {
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/* limits are stored as unsigned 32-bit data */
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info->dqi_max_spc_limit = 0xffffffffLL << QUOTABLOCK_BITS;
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info->dqi_max_ino_limit = 0xffffffff;
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} else {
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/*
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* Used space is stored as unsigned 64-bit value in bytes but
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* quota core supports only signed 64-bit values so use that
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* as a limit
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*/
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info->dqi_max_spc_limit = 0x7fffffffffffffffLL; /* 2^63-1 */
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info->dqi_max_ino_limit = 0x7fffffffffffffffLL;
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}
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info->dqi_bgrace = le32_to_cpu(dinfo.dqi_bgrace);
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info->dqi_igrace = le32_to_cpu(dinfo.dqi_igrace);
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/* No flags currently supported */
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info->dqi_flags = 0;
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qinfo->dqi_sb = sb;
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qinfo->dqi_type = type;
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qinfo->dqi_blocks = le32_to_cpu(dinfo.dqi_blocks);
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qinfo->dqi_free_blk = le32_to_cpu(dinfo.dqi_free_blk);
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qinfo->dqi_free_entry = le32_to_cpu(dinfo.dqi_free_entry);
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qinfo->dqi_blocksize_bits = V2_DQBLKSIZE_BITS;
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qinfo->dqi_usable_bs = 1 << V2_DQBLKSIZE_BITS;
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qinfo->dqi_qtree_depth = qtree_depth(qinfo);
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if (version == 0) {
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qinfo->dqi_entry_size = sizeof(struct v2r0_disk_dqblk);
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qinfo->dqi_ops = &v2r0_qtree_ops;
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} else {
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qinfo->dqi_entry_size = sizeof(struct v2r1_disk_dqblk);
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qinfo->dqi_ops = &v2r1_qtree_ops;
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}
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ret = 0;
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out:
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up_read(&dqopt->dqio_sem);
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return ret;
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}
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/* Write information header to quota file */
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static int v2_write_file_info(struct super_block *sb, int type)
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{
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struct v2_disk_dqinfo dinfo;
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struct quota_info *dqopt = sb_dqopt(sb);
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struct mem_dqinfo *info = &dqopt->info[type];
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struct qtree_mem_dqinfo *qinfo = info->dqi_priv;
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ssize_t size;
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down_write(&dqopt->dqio_sem);
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spin_lock(&dq_data_lock);
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info->dqi_flags &= ~DQF_INFO_DIRTY;
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dinfo.dqi_bgrace = cpu_to_le32(info->dqi_bgrace);
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dinfo.dqi_igrace = cpu_to_le32(info->dqi_igrace);
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/* No flags currently supported */
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dinfo.dqi_flags = cpu_to_le32(0);
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spin_unlock(&dq_data_lock);
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dinfo.dqi_blocks = cpu_to_le32(qinfo->dqi_blocks);
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dinfo.dqi_free_blk = cpu_to_le32(qinfo->dqi_free_blk);
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dinfo.dqi_free_entry = cpu_to_le32(qinfo->dqi_free_entry);
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size = sb->s_op->quota_write(sb, type, (char *)&dinfo,
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sizeof(struct v2_disk_dqinfo), V2_DQINFOOFF);
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up_write(&dqopt->dqio_sem);
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if (size != sizeof(struct v2_disk_dqinfo)) {
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quota_error(sb, "Can't write info structure");
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return -1;
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}
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return 0;
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}
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static void v2r0_disk2memdqb(struct dquot *dquot, void *dp)
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{
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struct v2r0_disk_dqblk *d = dp, empty;
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struct mem_dqblk *m = &dquot->dq_dqb;
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m->dqb_ihardlimit = le32_to_cpu(d->dqb_ihardlimit);
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m->dqb_isoftlimit = le32_to_cpu(d->dqb_isoftlimit);
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m->dqb_curinodes = le32_to_cpu(d->dqb_curinodes);
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m->dqb_itime = le64_to_cpu(d->dqb_itime);
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m->dqb_bhardlimit = v2_qbtos(le32_to_cpu(d->dqb_bhardlimit));
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m->dqb_bsoftlimit = v2_qbtos(le32_to_cpu(d->dqb_bsoftlimit));
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m->dqb_curspace = le64_to_cpu(d->dqb_curspace);
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m->dqb_btime = le64_to_cpu(d->dqb_btime);
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/* We need to escape back all-zero structure */
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memset(&empty, 0, sizeof(struct v2r0_disk_dqblk));
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empty.dqb_itime = cpu_to_le64(1);
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if (!memcmp(&empty, dp, sizeof(struct v2r0_disk_dqblk)))
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m->dqb_itime = 0;
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}
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static void v2r0_mem2diskdqb(void *dp, struct dquot *dquot)
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{
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struct v2r0_disk_dqblk *d = dp;
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struct mem_dqblk *m = &dquot->dq_dqb;
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struct qtree_mem_dqinfo *info =
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sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv;
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d->dqb_ihardlimit = cpu_to_le32(m->dqb_ihardlimit);
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d->dqb_isoftlimit = cpu_to_le32(m->dqb_isoftlimit);
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d->dqb_curinodes = cpu_to_le32(m->dqb_curinodes);
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d->dqb_itime = cpu_to_le64(m->dqb_itime);
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d->dqb_bhardlimit = cpu_to_le32(v2_stoqb(m->dqb_bhardlimit));
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d->dqb_bsoftlimit = cpu_to_le32(v2_stoqb(m->dqb_bsoftlimit));
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d->dqb_curspace = cpu_to_le64(m->dqb_curspace);
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d->dqb_btime = cpu_to_le64(m->dqb_btime);
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d->dqb_id = cpu_to_le32(from_kqid(&init_user_ns, dquot->dq_id));
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if (qtree_entry_unused(info, dp))
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d->dqb_itime = cpu_to_le64(1);
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}
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static int v2r0_is_id(void *dp, struct dquot *dquot)
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{
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struct v2r0_disk_dqblk *d = dp;
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struct qtree_mem_dqinfo *info =
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sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv;
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if (qtree_entry_unused(info, dp))
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return 0;
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return qid_eq(make_kqid(&init_user_ns, dquot->dq_id.type,
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le32_to_cpu(d->dqb_id)),
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dquot->dq_id);
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}
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static void v2r1_disk2memdqb(struct dquot *dquot, void *dp)
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{
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struct v2r1_disk_dqblk *d = dp, empty;
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struct mem_dqblk *m = &dquot->dq_dqb;
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m->dqb_ihardlimit = le64_to_cpu(d->dqb_ihardlimit);
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m->dqb_isoftlimit = le64_to_cpu(d->dqb_isoftlimit);
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m->dqb_curinodes = le64_to_cpu(d->dqb_curinodes);
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m->dqb_itime = le64_to_cpu(d->dqb_itime);
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m->dqb_bhardlimit = v2_qbtos(le64_to_cpu(d->dqb_bhardlimit));
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m->dqb_bsoftlimit = v2_qbtos(le64_to_cpu(d->dqb_bsoftlimit));
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m->dqb_curspace = le64_to_cpu(d->dqb_curspace);
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m->dqb_btime = le64_to_cpu(d->dqb_btime);
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/* We need to escape back all-zero structure */
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memset(&empty, 0, sizeof(struct v2r1_disk_dqblk));
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empty.dqb_itime = cpu_to_le64(1);
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if (!memcmp(&empty, dp, sizeof(struct v2r1_disk_dqblk)))
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m->dqb_itime = 0;
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}
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static void v2r1_mem2diskdqb(void *dp, struct dquot *dquot)
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{
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struct v2r1_disk_dqblk *d = dp;
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struct mem_dqblk *m = &dquot->dq_dqb;
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struct qtree_mem_dqinfo *info =
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sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv;
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d->dqb_ihardlimit = cpu_to_le64(m->dqb_ihardlimit);
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d->dqb_isoftlimit = cpu_to_le64(m->dqb_isoftlimit);
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d->dqb_curinodes = cpu_to_le64(m->dqb_curinodes);
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d->dqb_itime = cpu_to_le64(m->dqb_itime);
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d->dqb_bhardlimit = cpu_to_le64(v2_stoqb(m->dqb_bhardlimit));
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d->dqb_bsoftlimit = cpu_to_le64(v2_stoqb(m->dqb_bsoftlimit));
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d->dqb_curspace = cpu_to_le64(m->dqb_curspace);
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d->dqb_btime = cpu_to_le64(m->dqb_btime);
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d->dqb_id = cpu_to_le32(from_kqid(&init_user_ns, dquot->dq_id));
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if (qtree_entry_unused(info, dp))
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d->dqb_itime = cpu_to_le64(1);
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}
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static int v2r1_is_id(void *dp, struct dquot *dquot)
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{
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struct v2r1_disk_dqblk *d = dp;
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struct qtree_mem_dqinfo *info =
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sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv;
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if (qtree_entry_unused(info, dp))
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return 0;
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return qid_eq(make_kqid(&init_user_ns, dquot->dq_id.type,
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le32_to_cpu(d->dqb_id)),
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dquot->dq_id);
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}
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static int v2_read_dquot(struct dquot *dquot)
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{
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struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
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int ret;
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down_read(&dqopt->dqio_sem);
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ret = qtree_read_dquot(
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sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv,
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dquot);
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up_read(&dqopt->dqio_sem);
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return ret;
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}
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static int v2_write_dquot(struct dquot *dquot)
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{
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struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
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int ret;
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bool alloc = false;
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/*
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* If space for dquot is already allocated, we don't need any
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* protection as we'll only overwrite the place of dquot. We are
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* still protected by concurrent writes of the same dquot by
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* dquot->dq_lock.
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*/
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if (!dquot->dq_off) {
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alloc = true;
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down_write(&dqopt->dqio_sem);
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} else {
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down_read(&dqopt->dqio_sem);
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}
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ret = qtree_write_dquot(
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sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv,
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dquot);
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if (alloc)
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up_write(&dqopt->dqio_sem);
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else
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up_read(&dqopt->dqio_sem);
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return ret;
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}
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static int v2_release_dquot(struct dquot *dquot)
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{
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struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
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int ret;
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down_write(&dqopt->dqio_sem);
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ret = qtree_release_dquot(sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv, dquot);
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up_write(&dqopt->dqio_sem);
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return ret;
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}
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static int v2_free_file_info(struct super_block *sb, int type)
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{
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kfree(sb_dqinfo(sb, type)->dqi_priv);
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return 0;
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}
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static int v2_get_next_id(struct super_block *sb, struct kqid *qid)
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{
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struct quota_info *dqopt = sb_dqopt(sb);
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int ret;
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down_read(&dqopt->dqio_sem);
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ret = qtree_get_next_id(sb_dqinfo(sb, qid->type)->dqi_priv, qid);
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up_read(&dqopt->dqio_sem);
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return ret;
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}
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static const struct quota_format_ops v2_format_ops = {
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.check_quota_file = v2_check_quota_file,
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.read_file_info = v2_read_file_info,
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.write_file_info = v2_write_file_info,
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.free_file_info = v2_free_file_info,
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.read_dqblk = v2_read_dquot,
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.commit_dqblk = v2_write_dquot,
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.release_dqblk = v2_release_dquot,
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.get_next_id = v2_get_next_id,
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};
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static struct quota_format_type v2r0_quota_format = {
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.qf_fmt_id = QFMT_VFS_V0,
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.qf_ops = &v2_format_ops,
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.qf_owner = THIS_MODULE
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};
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static struct quota_format_type v2r1_quota_format = {
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.qf_fmt_id = QFMT_VFS_V1,
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.qf_ops = &v2_format_ops,
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.qf_owner = THIS_MODULE
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};
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static int __init init_v2_quota_format(void)
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{
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int ret;
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ret = register_quota_format(&v2r0_quota_format);
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if (ret)
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return ret;
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return register_quota_format(&v2r1_quota_format);
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}
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static void __exit exit_v2_quota_format(void)
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{
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unregister_quota_format(&v2r0_quota_format);
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unregister_quota_format(&v2r1_quota_format);
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}
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module_init(init_v2_quota_format);
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module_exit(exit_v2_quota_format);
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