[PATCH] [12/13] quota-12-compat

This patch implements configurable backward compatible quota interface.
Maybe this isn't needed in 2.5 but as some people want to use patches
in 2.4 where it's necessary I have implemented it.

arch/ia64/ia32/ia32_entry.S

@@ -310,7 +310,7 @@ ia32_syscall_table:
 	data8 sys32_ni_syscall	/* init_module */
 	data8 sys32_ni_syscall	/* delete_module */
 	data8 sys32_ni_syscall	/* get_kernel_syms */  /* 130 */
-	data8 sys_quotactl
+	data8 sys32_quotactl
 	data8 sys_getpgid
 	data8 sys_fchdir
 	data8 sys32_ni_syscall	/* sys_bdflush */

arch/ia64/ia32/sys_ia32.c

@@ -3669,6 +3669,97 @@ getname32 (const char *filename)
 	return result;
 }
 
+extern asmlinkage long sys_quotactl(int cmd, const char *special, int id, caddr_t addr);
+
+#ifdef CONFIG_QIFACE_COMPAT
+#ifdef CONFIG_QIFACE_V1
+struct user_dqblk32 {
+	__u32 dqb_bhardlimit;
+	__u32 dqb_bsoftlimit;
+	__u32 dqb_curblocks;
+	__u32 dqb_ihardlimit;
+	__u32 dqb_isoftlimit;
+	__u32 dqb_curinodes;
+	__kernel_time_t32 dqb_btime;
+	__kernel_time_t32 dqb_itime;
+};
+typedef struct v1c_mem_dqblk comp_dqblk_t;
+
+#define Q_COMP_GETQUOTA Q_V1_GETQUOTA
+#define Q_COMP_SETQUOTA Q_V1_SETQUOTA
+#define Q_COMP_SETQLIM Q_V1_SETQLIM
+#define Q_COMP_SETUSE Q_V1_SETUSE
+#else
+struct user_dqblk32 {
+	__u32 dqb_ihardlimit;
+	__u32 dqb_isoftlimit;
+	__u32 dqb_curinodes;
+	__u32 dqb_bhardlimit;
+	__u32 dqb_bsoftlimit;
+	__u64 dqb_curspace;
+	__kernel_time_t32 dqb_btime;
+	__kernel_time_t32 dqb_itime;
+};
+typedef struct v2c_mem_dqblk comp_dqblk_t;
+
+#define Q_COMP_GETQUOTA Q_V2_GETQUOTA
+#define Q_COMP_SETQUOTA Q_V2_SETQUOTA
+#define Q_COMP_SETQLIM Q_V2_SETQLIM
+#define Q_COMP_SETUSE Q_V2_SETUSE
+#endif
+
+asmlinkage long sys32_quotactl(int cmd, const char *special, int id, caddr_t addr)
+{
+	int cmds = cmd >> SUBCMDSHIFT;
+	long err;
+	comp_dqblk_t d;
+	mm_segment_t old_fs;
+	char *spec;
+	
+	switch (cmds) {
+		case Q_COMP_GETQUOTA:
+			break;
+		case Q_COMP_SETQUOTA:
+		case Q_COMP_SETUSE:
+		case Q_COMP_SETQLIM:
+			if (copy_from_user(&d, (struct user_dqblk32 *)addr,
+					    sizeof (struct user_dqblk32)))
+				return -EFAULT;
+			d.dqb_itime = ((struct user_dqblk32 *)&d)->dqb_itime;
+			d.dqb_btime = ((struct user_dqblk32 *)&d)->dqb_btime;
+			break;
+	default:
+		return sys_quotactl(cmd, special, id, (__kernel_caddr_t)addr);
+	}
+	spec = getname (special);
+	err = PTR_ERR(spec);
+	if (IS_ERR(spec)) return err;
+	old_fs = get_fs();
+	set_fs (KERNEL_DS);
+	err = sys_quotactl(cmd, (const char *)spec, id, (__kernel_caddr_t)&d);
+	set_fs (old_fs);
+	putname (spec);
+	if (err)
+		return err;
+	if (cmds == Q_COMP_GETQUOTA) {
+		__kernel_time_t b = d.dqb_btime, i = d.dqb_itime;
+		((struct user_dqblk32 *)&d)->dqb_itime = i;
+		((struct user_dqblk32 *)&d)->dqb_btime = b;
+		if (copy_to_user ((struct user_dqblk32 *)addr, &d,
+				  sizeof (struct user_dqblk32)))
+			return -EFAULT;
+	}
+	return 0;
+}
+
+#else
+/* No conversion needed for new interface */
+asmlinkage long sys32_quotactl(int cmd, const char *special, int id, caddr_t addr)
+{
+	return sys_quotactl(cmd, special, id, addr);
+}
+#endif
+
 asmlinkage long
 sys32_sched_rr_get_interval (pid_t pid, struct timespec32 *interval)
 {

arch/s390x/kernel/linux32.c

@@ -897,6 +897,97 @@ asmlinkage long sys32_fcntl64(unsigned int fd, unsigned int cmd, unsigned long a
 	return sys32_fcntl(fd, cmd, arg);
 }
 
+extern asmlinkage int sys_quotactl(int cmd, const char *special, int id, caddr_t addr);
+
+#ifdef CONFIG_QIFACE_COMPAT
+#ifdef CONFIG_QIFACE_V1
+struct user_dqblk32 {
+	__u32 dqb_bhardlimit;
+	__u32 dqb_bsoftlimit;
+	__u32 dqb_curblocks;
+	__u32 dqb_ihardlimit;
+	__u32 dqb_isoftlimit;
+	__u32 dqb_curinodes;
+	__kernel_time_t32 dqb_btime;
+	__kernel_time_t32 dqb_itime;
+};
+typedef struct v1c_mem_dqblk comp_dqblk_t;
+
+#define Q_COMP_GETQUOTA Q_V1_GETQUOTA
+#define Q_COMP_SETQUOTA Q_V1_SETQUOTA
+#define Q_COMP_SETQLIM Q_V1_SETQLIM
+#define Q_COMP_SETUSE Q_V1_SETUSE
+#else
+struct user_dqblk32 {
+	__u32 dqb_ihardlimit;
+	__u32 dqb_isoftlimit;
+	__u32 dqb_curinodes;
+	__u32 dqb_bhardlimit;
+	__u32 dqb_bsoftlimit;
+	__u64 dqb_curspace;
+	__kernel_time_t32 dqb_btime;
+	__kernel_time_t32 dqb_itime;
+};
+typedef struct v2c_mem_dqblk comp_dqblk_t;
+
+#define Q_COMP_GETQUOTA Q_V2_GETQUOTA
+#define Q_COMP_SETQUOTA Q_V2_SETQUOTA
+#define Q_COMP_SETQLIM Q_V2_SETQLIM
+#define Q_COMP_SETUSE Q_V2_SETUSE
+#endif
+
+asmlinkage int sys32_quotactl(int cmd, const char *special, int id, caddr_t addr)
+{
+	int cmds = cmd >> SUBCMDSHIFT;
+	int err;
+	comp_dqblk_t d;
+	mm_segment_t old_fs;
+	char *spec;
+	
+	switch (cmds) {
+		case Q_COMP_GETQUOTA:
+			break;
+		case Q_COMP_SETQUOTA:
+		case Q_COMP_SETUSE:
+		case Q_COMP_SETQLIM:
+			if (copy_from_user(&d, (struct user_dqblk32 *)addr,
+					    sizeof (struct user_dqblk32)))
+				return -EFAULT;
+			d.dqb_itime = ((struct user_dqblk32 *)&d)->dqb_itime;
+			d.dqb_btime = ((struct user_dqblk32 *)&d)->dqb_btime;
+			break;
+	default:
+		return sys_quotactl(cmd, special, id, (__kernel_caddr_t)addr);
+	}
+	spec = getname (special);
+	err = PTR_ERR(spec);
+	if (IS_ERR(spec)) return err;
+	old_fs = get_fs();
+	set_fs (KERNEL_DS);
+	err = sys_quotactl(cmd, (const char *)spec, id, (__kernel_caddr_t)&d);
+	set_fs (old_fs);
+	putname (spec);
+	if (err)
+		return err;
+	if (cmds == Q_COMP_GETQUOTA) {
+		__kernel_time_t b = d.dqb_btime, i = d.dqb_itime;
+		((struct user_dqblk32 *)&d)->dqb_itime = i;
+		((struct user_dqblk32 *)&d)->dqb_btime = b;
+		if (copy_to_user ((struct user_dqblk32 *)addr, &d,
+				  sizeof (struct user_dqblk32)))
+			return -EFAULT;
+	}
+	return 0;
+}
+
+#else
+/* No conversion needed for new interface */
+asmlinkage int sys32_quotactl(int cmd, const char *special, int id, caddr_t addr)
+{
+	return sys_quotactl(cmd, special, id, addr);
+}
+#endif
+
 static inline int put_statfs (struct statfs32 *ubuf, struct statfs *kbuf)
 {
 	int err;

arch/s390x/kernel/wrapper32.S

@@ -586,7 +586,7 @@ sys32_quotactl_wrapper:
 	llgtr	%r3,%r3			# const char *
 	lgfr	%r4,%r4			# int
 	llgtr	%r5,%r5			# caddr_t
-	jg	sys_quotactl		# branch to system call
+	jg	sys32_quotactl		# branch to system call
 
 	.globl  sys32_getpgid_wrapper 
 sys32_getpgid_wrapper:

arch/sparc64/kernel/sys_sparc32.c

@@ -889,6 +889,97 @@ asmlinkage long sys32_fcntl64(unsigned int fd, unsigned int cmd, unsigned long a
 	return sys32_fcntl(fd, cmd, arg);
 }
 
+extern asmlinkage int sys_quotactl(int cmd, const char *special, int id, caddr_t addr);
+
+#ifdef CONFIG_QIFACE_COMPAT
+#ifdef CONFIG_QIFACE_V1
+struct user_dqblk32 {
+	__u32 dqb_bhardlimit;
+	__u32 dqb_bsoftlimit;
+	__u32 dqb_curblocks;
+	__u32 dqb_ihardlimit;
+	__u32 dqb_isoftlimit;
+	__u32 dqb_curinodes;
+	__kernel_time_t32 dqb_btime;
+	__kernel_time_t32 dqb_itime;
+};
+typedef struct v1c_mem_dqblk comp_dqblk_t;
+
+#define Q_COMP_GETQUOTA Q_V1_GETQUOTA
+#define Q_COMP_SETQUOTA Q_V1_SETQUOTA
+#define Q_COMP_SETQLIM Q_V1_SETQLIM
+#define Q_COMP_SETUSE Q_V1_SETUSE
+#else
+struct user_dqblk32 {
+	__u32 dqb_ihardlimit;
+	__u32 dqb_isoftlimit;
+	__u32 dqb_curinodes;
+	__u32 dqb_bhardlimit;
+	__u32 dqb_bsoftlimit;
+	__u64 dqb_curspace;
+	__kernel_time_t32 dqb_btime;
+	__kernel_time_t32 dqb_itime;
+};
+typedef struct v2c_mem_dqblk comp_dqblk_t;
+
+#define Q_COMP_GETQUOTA Q_V2_GETQUOTA
+#define Q_COMP_SETQUOTA Q_V2_SETQUOTA
+#define Q_COMP_SETQLIM Q_V2_SETQLIM
+#define Q_COMP_SETUSE Q_V2_SETUSE
+#endif
+
+asmlinkage int sys32_quotactl(int cmd, const char *special, int id, caddr_t addr)
+{
+	int cmds = cmd >> SUBCMDSHIFT;
+	int err;
+	comp_dqblk_t d;
+	mm_segment_t old_fs;
+	char *spec;
+	
+	switch (cmds) {
+		case Q_COMP_GETQUOTA:
+			break;
+		case Q_COMP_SETQUOTA:
+		case Q_COMP_SETUSE:
+		case Q_COMP_SETQLIM:
+			if (copy_from_user(&d, (struct user_dqblk32 *)addr,
+					    sizeof (struct user_dqblk32)))
+				return -EFAULT;
+			d.dqb_itime = ((struct user_dqblk32 *)&d)->dqb_itime;
+			d.dqb_btime = ((struct user_dqblk32 *)&d)->dqb_btime;
+			break;
+	default:
+		return sys_quotactl(cmd, special, id, (__kernel_caddr_t)addr);
+	}
+	spec = getname (special);
+	err = PTR_ERR(spec);
+	if (IS_ERR(spec)) return err;
+	old_fs = get_fs();
+	set_fs (KERNEL_DS);
+	err = sys_quotactl(cmd, (const char *)spec, id, (__kernel_caddr_t)&d);
+	set_fs (old_fs);
+	putname (spec);
+	if (err)
+		return err;
+	if (cmds == Q_COMP_GETQUOTA) {
+		__kernel_time_t b = d.dqb_btime, i = d.dqb_itime;
+		((struct user_dqblk32 *)&d)->dqb_itime = i;
+		((struct user_dqblk32 *)&d)->dqb_btime = b;
+		if (copy_to_user ((struct user_dqblk32 *)addr, &d,
+				  sizeof (struct user_dqblk32)))
+			return -EFAULT;
+	}
+	return 0;
+}
+
+#else
+/* No conversion needed for new interface */
+asmlinkage int sys32_quotactl(int cmd, const char *special, int id, caddr_t addr)
+{
+	return sys_quotactl(cmd, special, id, addr);
+}
+#endif
+
 static inline int put_statfs (struct statfs32 *ubuf, struct statfs *kbuf)
 {
 	int err;

arch/sparc64/kernel/systbls.S

@@ -52,7 +52,7 @@ sys_call_table32:
 /*150*/	.word sys_nis_syscall, sys_nis_syscall, sys_nis_syscall, sys_poll, sys_getdents64
 	.word sys32_fcntl64, sys_nis_syscall, sys32_statfs, sys32_fstatfs, sys_oldumount
 /*160*/	.word sys32_sched_setaffinity, sys32_sched_getaffinity, sys_getdomainname, sys_setdomainname, sys_nis_syscall
-	.word sys_quotactl, sys_nis_syscall, sys32_mount, sys_ustat, sys_setxattr
+	.word sys32_quotactl, sys_nis_syscall, sys32_mount, sys_ustat, sys_setxattr
 /*170*/	.word sys_lsetxattr, sys_fsetxattr, sys_getxattr, sys_lgetxattr, sys32_getdents
 	.word sys_setsid, sys_fchdir, sys_fgetxattr, sys_listxattr, sys_llistxattr
 /*180*/	.word sys_flistxattr, sys_removexattr, sys_lremovexattr, sys32_sigpending, sys32_query_module

fs/Config.help

@@ -18,6 +18,21 @@ CONFIG_QFMT_V2
   need this functionality say Y here. Note that you will need latest
   quota utilities for new quota format with this kernel.
 
+CONFIG_QIFACE_COMPAT
+  This option will enable old quota interface in kernel.
+  If you have old quota tools (version <= 3.04) and you don't want to
+  upgrade them say Y here.
+
+CONFIG_QIFACE_V1
+  This is the oldest quota interface. It was used for old quota format.
+  If you have old quota tools and you use old quota format choose this
+  interface (if unsure, this interface is the best one to choose).
+
+CONFIG_QIFACE_V2
+  This quota interface was used by VFS v0 quota format. If you need
+  support for VFS v0 quota format (eg. you're using quota on ReiserFS)
+  and you don't want to upgrade quota tools, choose this interface.
+
 CONFIG_MINIX_FS
   Minix is a simple operating system used in many classes about OS's.
   The minix file system (method to organize files on a hard disk

fs/Config.in

@@ -7,6 +7,12 @@ comment 'File systems'
 bool 'Quota support' CONFIG_QUOTA
 dep_tristate '  Old quota format support' CONFIG_QFMT_V1 $CONFIG_QUOTA
 dep_tristate '  VFS v0 quota format support' CONFIG_QFMT_V2 $CONFIG_QUOTA
+dep_mbool '  Compatible quota interfaces' CONFIG_QIFACE_COMPAT $CONFIG_QUOTA
+if [ "$CONFIG_QUOTA" = "y" -a "$CONFIG_QIFACE_COMPAT" = "y" ]; then
+   choice '    Compatible quota interfaces' \
+	"Original	CONFIG_QIFACE_V1 \
+	 VFSv0		CONFIG_QIFACE_V2" Original
+fi
 tristate 'Kernel automounter support' CONFIG_AUTOFS_FS
 tristate 'Kernel automounter version 4 support (also supports v3)' CONFIG_AUTOFS4_FS
 

fs/quota.c

@@ -11,6 +11,10 @@
 #include <asm/uaccess.h>
 #include <linux/kernel.h>
 #include <linux/smp_lock.h>
+#ifdef CONFIG_QIFACE_COMPAT
+#include <linux/quotacompat.h>
+#endif
+
 
 int nr_dquots, nr_free_dquots;
 
@@ -231,6 +235,381 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, cadd
 	return 0;
 }
 
+#ifdef CONFIG_QIFACE_COMPAT
+static int check_compat_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
+{
+	if (type >= MAXQUOTAS)
+		return -EINVAL;
+	/* Is operation supported? */
+	/* sb==NULL for GETSTATS calls */
+	if (sb && !sb->s_qcop)
+		return -ENOSYS;
+
+	switch (cmd) {
+		case Q_COMP_QUOTAON:
+			if (!sb->s_qcop->quota_on)
+				return -ENOSYS;
+			break;
+		case Q_COMP_QUOTAOFF:
+			if (!sb->s_qcop->quota_off)
+				return -ENOSYS;
+			break;
+		case Q_COMP_SYNC:
+			if (!sb->s_qcop->quota_sync)
+				return -ENOSYS;
+		break;
+#ifdef CONFIG_QIFACE_V2
+		case Q_V2_SETFLAGS:
+		case Q_V2_SETGRACE:
+		case Q_V2_SETINFO:
+			if (!sb->s_qcop->set_info)
+				return -ENOSYS;
+			break;
+		case Q_V2_GETINFO:
+			if (!sb->s_qcop->get_info)
+				return -ENOSYS;
+			break;
+		case Q_V2_SETQLIM:
+		case Q_V2_SETUSE:
+		case Q_V2_SETQUOTA:
+			if (!sb->s_qcop->set_dqblk)
+				return -ENOSYS;
+			break;
+		case Q_V2_GETQUOTA:
+			if (!sb->s_qcop->get_dqblk)
+				return -ENOSYS;
+			break;
+		case Q_V2_GETSTATS:
+			return 0;	/* GETSTATS need no other checks */
+#endif
+#ifdef CONFIG_QIFACE_V1
+		case Q_V1_SETQLIM:
+		case Q_V1_SETUSE:
+		case Q_V1_SETQUOTA:
+			if (!sb->s_qcop->set_dqblk)
+				return -ENOSYS;
+			break;
+		case Q_V1_GETQUOTA:
+			if (!sb->s_qcop->get_dqblk)
+				return -ENOSYS;
+			break;
+		case Q_V1_RSQUASH:
+			if (!sb->s_qcop->set_info)
+				return -ENOSYS;
+			break;
+		case Q_V1_GETSTATS:
+			return 0;	/* GETSTATS need no other checks */
+#endif
+		default:
+			return -EINVAL;
+	}
+
+	/* Is quota turned on for commands which need it? */
+	switch (cmd) {
+		case Q_V2_SETFLAGS:
+		case Q_V2_SETGRACE:
+		case Q_V2_SETINFO:
+		case Q_V2_GETINFO:
+		case Q_COMP_QUOTAOFF:
+		case Q_V1_RSQUASH:
+		case Q_V1_SETQUOTA:
+		case Q_V1_SETQLIM:
+		case Q_V1_SETUSE:
+		case Q_V2_SETQUOTA:
+		/* Q_V2_SETQLIM: collision with Q_V1_SETQLIM */
+		case Q_V2_SETUSE:
+		case Q_V1_GETQUOTA:
+		case Q_V2_GETQUOTA:
+			if (!sb_has_quota_enabled(sb, type))
+				return -ESRCH;
+	}
+#ifdef CONFIG_QIFACE_V1
+	if (cmd != Q_COMP_QUOTAON && cmd != Q_COMP_QUOTAOFF && cmd != Q_COMP_SYNC && sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id != QFMT_VFS_OLD)
+#else
+	if (cmd != Q_COMP_QUOTAON && cmd != Q_COMP_QUOTAOFF && cmd != Q_COMP_SYNC && sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id != QFMT_VFS_V0)
+#endif
+		return -ESRCH;
+
+	/* Check privileges */
+	if (cmd == Q_V1_GETQUOTA || cmd == Q_V2_GETQUOTA) {
+		if (((type == USRQUOTA && current->euid != id) ||
+		     (type == GRPQUOTA && !in_egroup_p(id))) &&
+		    !capable(CAP_SYS_ADMIN))
+			return -EPERM;
+	}
+	else if (cmd != Q_V1_GETSTATS && cmd != Q_V2_GETSTATS && cmd != Q_V2_GETINFO && cmd != Q_COMP_SYNC)
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+	return 0;
+}
+
+#ifdef CONFIG_QIFACE_V1
+static int v1_set_rsquash(struct super_block *sb, int type, int flag)
+{
+	struct if_dqinfo info;
+
+	info.dqi_valid = IIF_FLAGS;
+	info.dqi_flags = flag ? V1_DQF_RSQUASH : 0;
+	return sb->s_qcop->set_info(sb, type, &info);
+}
+
+static int v1_get_dqblk(struct super_block *sb, int type, qid_t id, struct v1c_mem_dqblk *mdq)
+{
+	struct if_dqblk idq;
+	int ret;
+
+	if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)) < 0)
+		return ret;
+	mdq->dqb_ihardlimit = idq.dqb_ihardlimit;
+	mdq->dqb_isoftlimit = idq.dqb_isoftlimit;
+	mdq->dqb_curinodes = idq.dqb_curinodes;
+	mdq->dqb_bhardlimit = idq.dqb_bhardlimit;
+	mdq->dqb_bsoftlimit = idq.dqb_bsoftlimit;
+	mdq->dqb_curblocks = toqb(idq.dqb_curspace);
+	mdq->dqb_itime = idq.dqb_itime;
+	mdq->dqb_btime = idq.dqb_btime;
+	if (id == 0) {	/* Times for id 0 are in fact grace times */
+		struct if_dqinfo info;
+
+		if ((ret = sb->s_qcop->get_info(sb, type, &info)) < 0)
+			return ret;
+		mdq->dqb_btime = info.dqi_bgrace;
+		mdq->dqb_itime = info.dqi_igrace;
+	}
+	return 0;
+}
+
+static int v1_set_dqblk(struct super_block *sb, int type, int cmd, qid_t id, struct v1c_mem_dqblk *mdq)
+{
+	struct if_dqblk idq;
+	int ret;
+
+	idq.dqb_valid = 0;
+	if (cmd == Q_V1_SETQUOTA || cmd == Q_V1_SETQLIM) {
+		idq.dqb_ihardlimit = mdq->dqb_ihardlimit;
+		idq.dqb_isoftlimit = mdq->dqb_isoftlimit;
+		idq.dqb_bhardlimit = mdq->dqb_bhardlimit;
+		idq.dqb_bsoftlimit = mdq->dqb_bsoftlimit;
+		idq.dqb_valid |= QIF_LIMITS;
+	}
+	if (cmd == Q_V1_SETQUOTA || cmd == Q_V1_SETUSE) {
+		idq.dqb_curinodes = mdq->dqb_curinodes;
+		idq.dqb_curspace = ((qsize_t)mdq->dqb_curblocks) << QUOTABLOCK_BITS;
+		idq.dqb_valid |= QIF_USAGE;
+	}
+	ret = sb->s_qcop->set_dqblk(sb, type, id, &idq);
+	if (!ret && id == 0 && cmd == Q_V1_SETQUOTA) {	/* Times for id 0 are in fact grace times */
+		struct if_dqinfo info;
+
+		info.dqi_bgrace = mdq->dqb_btime;
+		info.dqi_igrace = mdq->dqb_itime;
+		info.dqi_valid = IIF_BGRACE | IIF_IGRACE;
+		ret = sb->s_qcop->set_info(sb, type, &info);
+	}
+	return ret;
+}
+
+static void v1_get_stats(struct v1c_dqstats *dst)
+{
+	memcpy(dst, &dqstats, sizeof(dqstats));
+}
+#endif
+
+#ifdef CONFIG_QIFACE_V2
+static int v2_get_info(struct super_block *sb, int type, struct v2c_mem_dqinfo *oinfo)
+{
+	struct if_dqinfo info;
+	int ret;
+
+	if ((ret = sb->s_qcop->get_info(sb, type, &info)) < 0)
+		return ret;
+	oinfo->dqi_bgrace = info.dqi_bgrace;
+	oinfo->dqi_igrace = info.dqi_igrace;
+	oinfo->dqi_flags = info.dqi_flags;
+	oinfo->dqi_blocks = sb_dqopt(sb)->info[type].u.v2_i.dqi_blocks;
+	oinfo->dqi_free_blk = sb_dqopt(sb)->info[type].u.v2_i.dqi_free_blk;
+	oinfo->dqi_free_entry = sb_dqopt(sb)->info[type].u.v2_i.dqi_free_entry;
+	return 0;
+}
+
+static int v2_set_info(struct super_block *sb, int type, int cmd, struct v2c_mem_dqinfo *oinfo)
+{
+	struct if_dqinfo info;
+
+	info.dqi_valid = 0;
+	if (cmd == Q_V2_SETGRACE || cmd == Q_V2_SETINFO) {
+		info.dqi_bgrace = oinfo->dqi_bgrace;
+		info.dqi_igrace = oinfo->dqi_igrace;
+		info.dqi_valid |= IIF_BGRACE | IIF_IGRACE;
+	}
+	if (cmd == Q_V2_SETFLAGS || cmd == Q_V2_SETINFO) {
+		info.dqi_flags = oinfo->dqi_flags;
+		info.dqi_valid |= IIF_FLAGS;
+	}
+	/* We don't simulate deadly effects of setting other parameters ;-) */
+	return sb->s_qcop->set_info(sb, type, &info);
+}
+
+static int v2_get_dqblk(struct super_block *sb, int type, qid_t id, struct v2c_mem_dqblk *mdq)
+{
+	struct if_dqblk idq;
+	int ret;
+
+	if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)) < 0)
+		return ret;
+	mdq->dqb_ihardlimit = idq.dqb_ihardlimit;
+	mdq->dqb_isoftlimit = idq.dqb_isoftlimit;
+	mdq->dqb_curinodes = idq.dqb_curinodes;
+	mdq->dqb_bhardlimit = idq.dqb_bhardlimit;
+	mdq->dqb_bsoftlimit = idq.dqb_bsoftlimit;
+	mdq->dqb_curspace = idq.dqb_curspace;
+	mdq->dqb_itime = idq.dqb_itime;
+	mdq->dqb_btime = idq.dqb_btime;
+	return 0;
+}
+
+static int v2_set_dqblk(struct super_block *sb, int type, int cmd, qid_t id, struct v2c_mem_dqblk *mdq)
+{
+	struct if_dqblk idq;
+
+	idq.dqb_valid = 0;
+	if (cmd == Q_V2_SETQUOTA || cmd == Q_V2_SETQLIM) {
+		idq.dqb_ihardlimit = mdq->dqb_ihardlimit;
+		idq.dqb_isoftlimit = mdq->dqb_isoftlimit;
+		idq.dqb_bhardlimit = mdq->dqb_bhardlimit;
+		idq.dqb_bsoftlimit = mdq->dqb_bsoftlimit;
+		idq.dqb_valid |= QIF_LIMITS;
+	}
+	if (cmd == Q_V2_SETQUOTA || cmd == Q_V2_SETUSE) {
+		idq.dqb_curinodes = mdq->dqb_curinodes;
+		idq.dqb_curspace = mdq->dqb_curspace;
+		idq.dqb_valid |= QIF_USAGE;
+	}
+	return sb->s_qcop->set_dqblk(sb, type, id, &idq);
+}
+
+static void v2_get_stats(struct v2c_dqstats *dst)
+{
+	memcpy(dst, &dqstats, sizeof(dqstats));
+	dst->version = __DQUOT_NUM_VERSION__;
+}
+#endif
+
+/* Handle requests to old interface */
+static int do_compat_quotactl(struct super_block *sb, int type, int cmd, qid_t id, caddr_t addr)
+{
+	int ret;
+
+	switch (cmd) {
+		case Q_COMP_QUOTAON: {
+			char *pathname;
+
+			if (IS_ERR(pathname = getname(addr)))
+				return PTR_ERR(pathname);
+#ifdef CONFIG_QIFACE_V1
+			ret = sb->s_qcop->quota_on(sb, type, QFMT_VFS_OLD, pathname);
+#else
+			ret = sb->s_qcop->quota_on(sb, type, QFMT_VFS_V0, pathname);
+#endif
+			putname(pathname);
+			return ret;
+		}
+		case Q_COMP_QUOTAOFF:
+			return sb->s_qcop->quota_off(sb, type);
+		case Q_COMP_SYNC:
+			return sb->s_qcop->quota_sync(sb, type);
+#ifdef CONFIG_QIFACE_V1
+		case Q_V1_RSQUASH: {
+			int flag;
+
+			if (copy_from_user(&flag, addr, sizeof(flag)))
+				return -EFAULT;
+			return v1_set_rsquash(sb, type, flag);
+		}
+		case Q_V1_GETQUOTA: {
+			struct v1c_mem_dqblk mdq;
+
+			if ((ret = v1_get_dqblk(sb, type, id, &mdq)))
+				return ret;
+			if (copy_to_user(addr, &mdq, sizeof(mdq)))
+				return -EFAULT;
+			return 0;
+		}
+		case Q_V1_SETQLIM:
+		case Q_V1_SETUSE:
+		case Q_V1_SETQUOTA: {
+			struct v1c_mem_dqblk mdq;
+
+			if (copy_from_user(&mdq, addr, sizeof(mdq)))
+				return -EFAULT;
+			return v1_set_dqblk(sb, type, cmd, id, &mdq);
+		}
+		case Q_V1_GETSTATS: {
+			struct v1c_dqstats dst;
+
+			v1_get_stats(&dst);
+			if (copy_to_user(addr, &dst, sizeof(dst)))
+				return -EFAULT;
+			return 0;
+		}
+#endif
+#ifdef CONFIG_QIFACE_V2
+		case Q_V2_GETINFO: {
+			struct v2c_mem_dqinfo info;
+
+			if ((ret = v2_get_info(sb, type, &info)))
+				return ret;
+			if (copy_to_user(addr, &info, sizeof(info)))
+				return -EFAULT;
+			return 0;
+		}
+		case Q_V2_SETFLAGS:
+		case Q_V2_SETGRACE:
+		case Q_V2_SETINFO: {
+			struct v2c_mem_dqinfo info;
+
+			if (copy_from_user(&info, addr, sizeof(info)))
+				return -EFAULT;
+			
+			return v2_set_info(sb, type, cmd, &info);
+		}
+		case Q_V2_GETQUOTA: {
+			struct v2c_mem_dqblk mdq;
+
+			if ((ret = v2_get_dqblk(sb, type, id, &mdq)))
+				return ret;
+			if (copy_to_user(addr, &mdq, sizeof(mdq)))
+				return -EFAULT;
+			return 0;
+		}
+		case Q_V2_SETUSE:
+		case Q_V2_SETQLIM:
+		case Q_V2_SETQUOTA: {
+			struct v2c_mem_dqblk mdq;
+
+			if (copy_from_user(&mdq, addr, sizeof(mdq)))
+				return -EFAULT;
+			return v2_set_dqblk(sb, type, cmd, id, &mdq);
+		}
+		case Q_V2_GETSTATS: {
+			struct v2c_dqstats dst;
+
+			v2_get_stats(&dst);
+			if (copy_to_user(addr, &dst, sizeof(dst)))
+				return -EFAULT;
+			return 0;
+		}
+#endif
+	}
+	BUG();
+	return 0;
+}
+#endif
+
+/* Macros for short-circuiting the compatibility tests */
+#define NEW_COMMAND(c) ((c) & (0x80 << 16))
+#define XQM_COMMAND(c) (((c) & ('X' << 8)) == ('X' << 8))
+
 /*
  * This is the system call interface. This communicates with
  * the user-level programs. Currently this only supports diskquota
@@ -247,11 +626,25 @@ asmlinkage long sys_quotactl(unsigned int cmd, const char *special, qid_t id, ca
 	cmds = cmd >> SUBCMDSHIFT;
 	type = cmd & SUBCMDMASK;
 
+#ifdef CONFIG_QIFACE_COMPAT
+	if (cmds != Q_V1_GETSTATS && cmds != Q_V2_GETSTATS && IS_ERR(sb = resolve_dev(special))) {
+		ret = PTR_ERR(sb);
+		sb = NULL;
+		goto out;
+	}
+	if (!NEW_COMMAND(cmds) && !XQM_COMMAND(cmds)) {
+		if ((ret = check_compat_quotactl_valid(sb, type, cmds, id)) < 0)
+			goto out;
+		ret = do_compat_quotactl(sb, type, cmds, id, addr);
+		goto out;
+	}
+#else
 	if (IS_ERR(sb = resolve_dev(special))) {
 		ret = PTR_ERR(sb);
 		sb = NULL;
 		goto out;
 	}
+#endif
 	if ((ret = check_quotactl_valid(sb, type, cmds, id)) < 0)
 		goto out;
 	ret = do_quotactl(sb, type, cmds, id, addr);

include/linux/quotacompat.h

+/*
+ *	Definition of symbols used for backward compatible interface
+ */
+
+#ifndef _LINUX_QUOTACOMPAT_
+#define _LINUX_QUOTACOMPAT_
+
+#include <linux/types.h>
+#include <linux/quota.h>
+
+struct v1c_mem_dqblk {
+	__u32 dqb_bhardlimit;	/* absolute limit on disk blks alloc */
+	__u32 dqb_bsoftlimit;	/* preferred limit on disk blks */
+	__u32 dqb_curblocks;	/* current block count */
+	__u32 dqb_ihardlimit;	/* maximum # allocated inodes */
+	__u32 dqb_isoftlimit;	/* preferred inode limit */
+	__u32 dqb_curinodes;	/* current # allocated inodes */
+	time_t dqb_btime;	/* time limit for excessive disk use */
+	time_t dqb_itime;	/* time limit for excessive files */
+};
+
+struct v1c_dqstats {
+	__u32 lookups;
+	__u32 drops;
+	__u32 reads;
+	__u32 writes;
+	__u32 cache_hits;
+	__u32 allocated_dquots;
+	__u32 free_dquots;
+	__u32 syncs;
+};
+
+struct v2c_mem_dqblk {
+	unsigned int dqb_ihardlimit;
+	unsigned int dqb_isoftlimit;
+	unsigned int dqb_curinodes;
+	unsigned int dqb_bhardlimit;
+	unsigned int dqb_bsoftlimit;
+	qsize_t dqb_curspace;
+	__kernel_time_t dqb_btime;
+	__kernel_time_t dqb_itime;
+};
+
+struct v2c_mem_dqinfo {
+	unsigned int dqi_bgrace;
+	unsigned int dqi_igrace;
+	unsigned int dqi_flags;
+	unsigned int dqi_blocks;
+	unsigned int dqi_free_blk;
+	unsigned int dqi_free_entry;
+};
+
+struct v2c_dqstats {
+	__u32 lookups;
+	__u32 drops;
+	__u32 reads;
+	__u32 writes;
+	__u32 cache_hits;
+	__u32 allocated_dquots;
+	__u32 free_dquots;
+	__u32 syncs;
+	__u32 version;
+};
+
+#define Q_COMP_QUOTAON  0x0100	/* enable quotas */
+#define Q_COMP_QUOTAOFF 0x0200	/* disable quotas */
+#define Q_COMP_SYNC     0x0600	/* sync disk copy of a filesystems quotas */
+
+#define Q_V1_GETQUOTA 0x0300	/* get limits and usage */
+#define Q_V1_SETQUOTA 0x0400	/* set limits and usage */
+#define Q_V1_SETUSE   0x0500	/* set usage */
+#define Q_V1_SETQLIM  0x0700	/* set limits */
+#define Q_V1_GETSTATS 0x0800	/* get collected stats */
+#define Q_V1_RSQUASH  0x1000	/* set root_squash option */
+
+#define Q_V2_SETQLIM  0x0700	/* set limits */
+#define Q_V2_GETINFO  0x0900	/* get info about quotas - graces, flags... */
+#define Q_V2_SETINFO  0x0A00	/* set info about quotas */
+#define Q_V2_SETGRACE 0x0B00	/* set inode and block grace */
+#define Q_V2_SETFLAGS 0x0C00	/* set flags for quota */
+#define Q_V2_GETQUOTA 0x0D00	/* get limits and usage */
+#define Q_V2_SETQUOTA 0x0E00	/* set limits and usage */
+#define Q_V2_SETUSE   0x0F00	/* set usage */
+#define Q_V2_GETSTATS 0x1100	/* get collected stats */
+
+#endif