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linux-next/fs/quota.c
Jan Kara 0ff5af8340 quota: quota core changes for quotaon on remount 
Currently, we just turn quotas off on remount of filesystem to read-only
state.  The patch below adds necessary framework so that we can turn quotas
off on remount RO but we are able to automatically reenable them again when
filesystem is remounted to RW state.  All we need to do is to keep references
to inodes of quota files when remounting RO and using these references to
reenable quotas when remounting RW.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-28 08:58:33 -07:00

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/*
* Quota code necessary even when VFS quota support is not compiled
* into the kernel. The interesting stuff is over in dquot.c, here
* we have symbols for initial quotactl(2) handling, the sysctl(2)
* variables, etc - things needed even when quota support disabled.
*/
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/slab.h>
#include <asm/current.h>
#include <asm/uaccess.h>
#include <linux/compat.h>
#include <linux/kernel.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/buffer_head.h>
#include <linux/capability.h>
#include <linux/quotaops.h>
#include <linux/types.h>
/* Check validity of generic quotactl commands */
static int generic_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
{
if (type >= MAXQUOTAS)
return -EINVAL;
if (!sb && cmd != Q_SYNC)
return -ENODEV;
/* Is operation supported? */
if (sb && !sb->s_qcop)
return -ENOSYS;
switch (cmd) {
case Q_GETFMT:
break;
case Q_QUOTAON:
if (!sb->s_qcop->quota_on)
return -ENOSYS;
break;
case Q_QUOTAOFF:
if (!sb->s_qcop->quota_off)
return -ENOSYS;
break;
case Q_SETINFO:
if (!sb->s_qcop->set_info)
return -ENOSYS;
break;
case Q_GETINFO:
if (!sb->s_qcop->get_info)
return -ENOSYS;
break;
case Q_SETQUOTA:
if (!sb->s_qcop->set_dqblk)
return -ENOSYS;
break;
case Q_GETQUOTA:
if (!sb->s_qcop->get_dqblk)
return -ENOSYS;
break;
case Q_SYNC:
if (sb && !sb->s_qcop->quota_sync)
return -ENOSYS;
break;
default:
return -EINVAL;
}
/* Is quota turned on for commands which need it? */
switch (cmd) {
case Q_GETFMT:
case Q_GETINFO:
case Q_SETINFO:
case Q_SETQUOTA:
case Q_GETQUOTA:
/* This is just informative test so we are satisfied without a lock */
if (!sb_has_quota_enabled(sb, type))
return -ESRCH;
}
/* Check privileges */
if (cmd == Q_GETQUOTA) {
if (((type == USRQUOTA && current->euid != id) ||
(type == GRPQUOTA && !in_egroup_p(id))) &&
!capable(CAP_SYS_ADMIN))
return -EPERM;
}
else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO)
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
return 0;
}
/* Check validity of XFS Quota Manager commands */
static int xqm_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
{
if (type >= XQM_MAXQUOTAS)
return -EINVAL;
if (!sb)
return -ENODEV;
if (!sb->s_qcop)
return -ENOSYS;
switch (cmd) {
case Q_XQUOTAON:
case Q_XQUOTAOFF:
case Q_XQUOTARM:
if (!sb->s_qcop->set_xstate)
return -ENOSYS;
break;
case Q_XGETQSTAT:
if (!sb->s_qcop->get_xstate)
return -ENOSYS;
break;
case Q_XSETQLIM:
if (!sb->s_qcop->set_xquota)
return -ENOSYS;
break;
case Q_XGETQUOTA:
if (!sb->s_qcop->get_xquota)
return -ENOSYS;
break;
case Q_XQUOTASYNC:
if (!sb->s_qcop->quota_sync)
return -ENOSYS;
break;
default:
return -EINVAL;
}
/* Check privileges */
if (cmd == Q_XGETQUOTA) {
if (((type == XQM_USRQUOTA && current->euid != id) ||
(type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
!capable(CAP_SYS_ADMIN))
return -EPERM;
} else if (cmd != Q_XGETQSTAT && cmd != Q_XQUOTASYNC) {
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
}
return 0;
}
static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
{
int error;
if (XQM_COMMAND(cmd))
error = xqm_quotactl_valid(sb, type, cmd, id);
else
error = generic_quotactl_valid(sb, type, cmd, id);
if (!error)
error = security_quotactl(cmd, type, id, sb);
return error;
}
static void quota_sync_sb(struct super_block *sb, int type)
{
int cnt;
sb->s_qcop->quota_sync(sb, type);
/* This is not very clever (and fast) but currently I don't know about
* any other simple way of getting quota data to disk and we must get
* them there for userspace to be visible... */
if (sb->s_op->sync_fs)
sb->s_op->sync_fs(sb, 1);
sync_blockdev(sb->s_bdev);
/*
* Now when everything is written we can discard the pagecache so
* that userspace sees the changes.
*/
mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (type != -1 && cnt != type)
continue;
if (!sb_has_quota_enabled(sb, cnt))
continue;
mutex_lock_nested(&sb_dqopt(sb)->files[cnt]->i_mutex, I_MUTEX_QUOTA);
truncate_inode_pages(&sb_dqopt(sb)->files[cnt]->i_data, 0);
mutex_unlock(&sb_dqopt(sb)->files[cnt]->i_mutex);
}
mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
}
void sync_dquots(struct super_block *sb, int type)
{
int cnt, dirty;
if (sb) {
if (sb->s_qcop->quota_sync)
quota_sync_sb(sb, type);
return;
}
spin_lock(&sb_lock);
restart:
list_for_each_entry(sb, &super_blocks, s_list) {
/* This test just improves performance so it needn't be reliable... */
for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++)
if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt)
&& info_any_dirty(&sb_dqopt(sb)->info[cnt]))
dirty = 1;
if (!dirty)
continue;
sb->s_count++;
spin_unlock(&sb_lock);
down_read(&sb->s_umount);
if (sb->s_root && sb->s_qcop->quota_sync)
quota_sync_sb(sb, type);
up_read(&sb->s_umount);
spin_lock(&sb_lock);
if (__put_super_and_need_restart(sb))
goto restart;
}
spin_unlock(&sb_lock);
}
/* Copy parameters and call proper function */
static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void __user *addr)
{
int ret;
switch (cmd) {
case Q_QUOTAON: {
char *pathname;
if (IS_ERR(pathname = getname(addr)))
return PTR_ERR(pathname);
ret = sb->s_qcop->quota_on(sb, type, id, pathname, 0);
putname(pathname);
return ret;
}
case Q_QUOTAOFF:
return sb->s_qcop->quota_off(sb, type, 0);
case Q_GETFMT: {
__u32 fmt;
down_read(&sb_dqopt(sb)->dqptr_sem);
if (!sb_has_quota_enabled(sb, type)) {
up_read(&sb_dqopt(sb)->dqptr_sem);
return -ESRCH;
}
fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
up_read(&sb_dqopt(sb)->dqptr_sem);
if (copy_to_user(addr, &fmt, sizeof(fmt)))
return -EFAULT;
return 0;
}
case Q_GETINFO: {
struct if_dqinfo info;
if ((ret = sb->s_qcop->get_info(sb, type, &info)))
return ret;
if (copy_to_user(addr, &info, sizeof(info)))
return -EFAULT;
return 0;
}
case Q_SETINFO: {
struct if_dqinfo info;
if (copy_from_user(&info, addr, sizeof(info)))
return -EFAULT;
return sb->s_qcop->set_info(sb, type, &info);
}
case Q_GETQUOTA: {
struct if_dqblk idq;
if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
return ret;
if (copy_to_user(addr, &idq, sizeof(idq)))
return -EFAULT;
return 0;
}
case Q_SETQUOTA: {
struct if_dqblk idq;
if (copy_from_user(&idq, addr, sizeof(idq)))
return -EFAULT;
return sb->s_qcop->set_dqblk(sb, type, id, &idq);
}
case Q_SYNC:
sync_dquots(sb, type);
return 0;
case Q_XQUOTAON:
case Q_XQUOTAOFF:
case Q_XQUOTARM: {
__u32 flags;
if (copy_from_user(&flags, addr, sizeof(flags)))
return -EFAULT;
return sb->s_qcop->set_xstate(sb, flags, cmd);
}
case Q_XGETQSTAT: {
struct fs_quota_stat fqs;
if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
return ret;
if (copy_to_user(addr, &fqs, sizeof(fqs)))
return -EFAULT;
return 0;
}
case Q_XSETQLIM: {
struct fs_disk_quota fdq;
if (copy_from_user(&fdq, addr, sizeof(fdq)))
return -EFAULT;
return sb->s_qcop->set_xquota(sb, type, id, &fdq);
}
case Q_XGETQUOTA: {
struct fs_disk_quota fdq;
if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
return ret;
if (copy_to_user(addr, &fdq, sizeof(fdq)))
return -EFAULT;
return 0;
}
case Q_XQUOTASYNC:
return sb->s_qcop->quota_sync(sb, type);
/* We never reach here unless validity check is broken */
default:
BUG();
}
return 0;
}
/*
* look up a superblock on which quota ops will be performed
* - use the name of a block device to find the superblock thereon
*/
static inline struct super_block *quotactl_block(const char __user *special)
{
#ifdef CONFIG_BLOCK
struct block_device *bdev;
struct super_block *sb;
char *tmp = getname(special);
if (IS_ERR(tmp))
return ERR_CAST(tmp);
bdev = lookup_bdev(tmp);
putname(tmp);
if (IS_ERR(bdev))
return ERR_CAST(bdev);
sb = get_super(bdev);
bdput(bdev);
if (!sb)
return ERR_PTR(-ENODEV);
return sb;
#else
return ERR_PTR(-ENODEV);
#endif
}
/*
* This is the system call interface. This communicates with
* the user-level programs. Currently this only supports diskquota
* calls. Maybe we need to add the process quotas etc. in the future,
* but we probably should use rlimits for that.
*/
asmlinkage long sys_quotactl(unsigned int cmd, const char __user *special, qid_t id, void __user *addr)
{
uint cmds, type;
struct super_block *sb = NULL;
int ret;
cmds = cmd >> SUBCMDSHIFT;
type = cmd & SUBCMDMASK;
if (cmds != Q_SYNC || special) {
sb = quotactl_block(special);
if (IS_ERR(sb))
return PTR_ERR(sb);
}
ret = check_quotactl_valid(sb, type, cmds, id);
if (ret >= 0)
ret = do_quotactl(sb, type, cmds, id, addr);
if (sb)
drop_super(sb);
return ret;
}
#if defined(CONFIG_COMPAT_FOR_U64_ALIGNMENT)
/*
* This code works only for 32 bit quota tools over 64 bit OS (x86_64, ia64)
* and is necessary due to alignment problems.
*/
struct compat_if_dqblk {
compat_u64 dqb_bhardlimit;
compat_u64 dqb_bsoftlimit;
compat_u64 dqb_curspace;
compat_u64 dqb_ihardlimit;
compat_u64 dqb_isoftlimit;
compat_u64 dqb_curinodes;
compat_u64 dqb_btime;
compat_u64 dqb_itime;
compat_uint_t dqb_valid;
};
/* XFS structures */
struct compat_fs_qfilestat {
compat_u64 dqb_bhardlimit;
compat_u64 qfs_nblks;
compat_uint_t qfs_nextents;
};
struct compat_fs_quota_stat {
__s8 qs_version;
__u16 qs_flags;
__s8 qs_pad;
struct compat_fs_qfilestat qs_uquota;
struct compat_fs_qfilestat qs_gquota;
compat_uint_t qs_incoredqs;
compat_int_t qs_btimelimit;
compat_int_t qs_itimelimit;
compat_int_t qs_rtbtimelimit;
__u16 qs_bwarnlimit;
__u16 qs_iwarnlimit;
};
asmlinkage long sys32_quotactl(unsigned int cmd, const char __user *special,
qid_t id, void __user *addr)
{
unsigned int cmds;
struct if_dqblk __user *dqblk;
struct compat_if_dqblk __user *compat_dqblk;
struct fs_quota_stat __user *fsqstat;
struct compat_fs_quota_stat __user *compat_fsqstat;
compat_uint_t data;
u16 xdata;
long ret;
cmds = cmd >> SUBCMDSHIFT;
switch (cmds) {
case Q_GETQUOTA:
dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
compat_dqblk = addr;
ret = sys_quotactl(cmd, special, id, dqblk);
if (ret)
break;
if (copy_in_user(compat_dqblk, dqblk, sizeof(*compat_dqblk)) ||
get_user(data, &dqblk->dqb_valid) ||
put_user(data, &compat_dqblk->dqb_valid))
ret = -EFAULT;
break;
case Q_SETQUOTA:
dqblk = compat_alloc_user_space(sizeof(struct if_dqblk));
compat_dqblk = addr;
ret = -EFAULT;
if (copy_in_user(dqblk, compat_dqblk, sizeof(*compat_dqblk)) ||
get_user(data, &compat_dqblk->dqb_valid) ||
put_user(data, &dqblk->dqb_valid))
break;
ret = sys_quotactl(cmd, special, id, dqblk);
break;
case Q_XGETQSTAT:
fsqstat = compat_alloc_user_space(sizeof(struct fs_quota_stat));
compat_fsqstat = addr;
ret = sys_quotactl(cmd, special, id, fsqstat);
if (ret)
break;
ret = -EFAULT;
/* Copying qs_version, qs_flags, qs_pad */
if (copy_in_user(compat_fsqstat, fsqstat,
offsetof(struct compat_fs_quota_stat, qs_uquota)))
break;
/* Copying qs_uquota */
if (copy_in_user(&compat_fsqstat->qs_uquota,
&fsqstat->qs_uquota,
sizeof(compat_fsqstat->qs_uquota)) ||
get_user(data, &fsqstat->qs_uquota.qfs_nextents) ||
put_user(data, &compat_fsqstat->qs_uquota.qfs_nextents))
break;
/* Copying qs_gquota */
if (copy_in_user(&compat_fsqstat->qs_gquota,
&fsqstat->qs_gquota,
sizeof(compat_fsqstat->qs_gquota)) ||
get_user(data, &fsqstat->qs_gquota.qfs_nextents) ||
put_user(data, &compat_fsqstat->qs_gquota.qfs_nextents))
break;
/* Copying the rest */
if (copy_in_user(&compat_fsqstat->qs_incoredqs,
&fsqstat->qs_incoredqs,
sizeof(struct compat_fs_quota_stat) -
offsetof(struct compat_fs_quota_stat, qs_incoredqs)) ||
get_user(xdata, &fsqstat->qs_iwarnlimit) ||
put_user(xdata, &compat_fsqstat->qs_iwarnlimit))
break;
ret = 0;
break;
default:
ret = sys_quotactl(cmd, special, id, addr);
}
return ret;
}
#endif
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