QUOTACTL
Section: Linux Programmer's Manual (2)
Updated: 2010-06-16
NAME
quotactl - manipulate disk quotas
SYNOPSIS
#include <sys/quota.h>
#include <xfs/xqm.h>
int quotactl(int cmd, const char *special, int id, caddr_t addr);
DESCRIPTION
The quota system can be used to set per-user and per-group limits on the
amount of disk space used on a file system.
For each user and/or group,
a soft limit and a hard limit can be set for each file system.
The hard limit can't be exceeded.
The soft limit can be exceeded, but warnings will ensue.
Moreover, the user can't exceed the soft limit for more than one week
(by default) at a time;
after this time, the soft limit counts as a hard limit.
The
quotactl()
call manipulates disk quotas.
The
cmd
argument indicates a command to be applied to the user or
group ID specified in
id.
To initialize the
cmd
argument, use the
QCMD(subcmd, type)
macro.
The
type
value is either
USRQUOTA,
for user quotas,
or
GRPQUOTA,
for group quotas.
The
subcmd
value is described below.
The
special
argument is a pointer to a null-terminated string containing the pathname
of the (mounted) block special device for the file system being manipulated.
The
addr
argument is the address of an optional, command-specific, data structure
that is copied in or out of the system.
The interpretation of
addr
is given with each command below.
The
subcmd
value is one of the following:
- Q_QUOTAON
-
Turn on quotas for a file system.
The
id
argument is the identification number of the quota format to be used.
Currently, there are three supported quota formats:
-
- QFMT_VFS_OLD
-
The original quota format.
- QFMT_VFS_V0
-
The standard VFS v0 quota format, which can handle 32-bit UIDs and GIDs
and quota limits up to 2^42 bytes and 2^32 inodes.
- QFMT_VFS_V1
-
A quota format that can handle 32-bit UIDs and GIDs
and quota limits of 2^64 bytes and 2^64 inodes.
-
The
addr
argument points to the pathname of a file containing the quotas for
the file system.
The quota file must exist; it is normally created with the
quotacheck(8)
program.
This operation requires privilege
(CAP_SYS_ADMIN).
- Q_QUOTAOFF
-
Turn off quotas for a file system.
The
addr
and
id
arguments are ignored.
This operation requires privilege
(CAP_SYS_ADMIN).
- Q_GETQUOTA
-
Get disk quota limits and current usage for user or group
id.
The
addr
argument is a pointer to a
dqblk
structure defined in
<sys/quota.h>
as follows:
/* uint64_t is an unsigned 64-bit integer;
uint32_t is an unsigned 32-bit integer */
struct dqblk { /* Definition since Linux 2.4.22 */
uint64_t dqb_bhardlimit; /* absolute limit on disk
quota blocks alloc */
uint64_t dqb_bsoftlimit; /* preferred limit on
disk quota blocks */
uint64_t dqb_curspace; /* current quota block
count */
uint64_t dqb_ihardlimit; /* maximum number of
allocated inodes */
uint64_t dqb_isoftlimit; /* preferred inode limit */
uint64_t dqb_curinodes; /* current number of
allocated inodes */
uint64_t dqb_btime; /* time limit for excessive
disk use */
uint64_t dqb_itime; /* time limit for excessive
files */
uint32_t dqb_valid; /* bit mask of QIF_*
constants */
};
/* Flags in dqb_valid that indicate which fields in
dqblk structure are valid. */
#define QIF_BLIMITS 1
#define QIF_SPACE 2
#define QIF_ILIMITS 4
#define QIF_INODES 8
#define QIF_BTIME 16
#define QIF_ITIME 32
#define QIF_LIMITS (QIF_BLIMITS | QIF_ILIMITS)
#define QIF_USAGE (QIF_SPACE | QIF_INODES)
#define QIF_TIMES (QIF_BTIME | QIF_ITIME)
#define QIF_ALL (QIF_LIMITS | QIF_USAGE | QIF_TIMES)
The
dqb_valid
field is a bit mask that is set to indicate the entries in the
dqblk
structure that are valid.
Currently, the kernel fills in all entries of the
dqblk
structure and marks them as valid in the
dqb_valid
field.
Unprivileged users may retrieve only their own quotas;
a privileged user
(CAP_SYS_ADMIN)
can retrieve the quotas of any user.
- Q_SETQUOTA
-
Set quota information for user or group
id,
using the information supplied in the
dqblk
structure pointed to by
addr.
The
dqb_valid
field of the
dqblk
structure indicates which entries in the structure have been set by the caller.
This operation supersedes the
Q_SETQLIM
and
Q_SETUSE
operations in the previous quota interfaces.
This operation requires privilege
(CAP_SYS_ADMIN).
- Q_GETINFO
-
Get information (like grace times) about quotafile.
The
addr
argument should be a pointer to a
dqinfo
structure.
This structure is defined in
<sys/quota.h>
as follows:
/* uint64_t is an unsigned 64-bit integer;
uint32_t is an unsigned 32-bit integer */
struct dqinfo { /* Defined since kernel 2.4.22 */
uint64_t dqi_bgrace; /* Time before block soft limit
becomes hard limit */
uint64_t dqi_igrace; /* Time before inode soft limit
becomes hard limit */
uint32_t dqi_flags; /* Flags for quotafile
(DQF_*) */
uint32_t dqi_valid;
};
/* Bits for dqi_flags */
/* Quota format QFMT_VFS_OLD */
#define V1_DQF_RSQUASH 1 /* Root squash enabled */
/* Other quota formats have no dqi_flags bits defined */
/* Flags in dqi_valid that indicate which fields in
dqinfo structure are valid. */
# define IIF_BGRACE 1
# define IIF_IGRACE 2
# define IIF_FLAGS 4
# define IIF_ALL (IIF_BGRACE | IIF_IGRACE | IIF_FLAGS)
The
dqi_valid
field in the
dqinfo
structure indicates the entries in the structure that are valid.
Currently, the kernel fills in all entries of the
dqinfo
structure and marks them all as valid in the
dqi_valid
field.
The
id
argument is ignored.
- Q_SETINFO
-
Set information about quotafile.
The
addr
argument should be a pointer to a
dqinfo
structure.
The
dqi_valid
field of the
dqinfo
structure indicates the entries in the structure
that have been set by the caller.
This operation supersedes the
Q_SETGRACE
and
Q_SETFLAGS
operations in the previous quota interfaces.
The
id
argument is ignored.
This operation requires privilege
(CAP_SYS_ADMIN).
- Q_GETFMT
-
Get quota format used on the specified file system.
The
addr
argument should be a pointer to a 4-byte buffer
where the format number will be stored.
- Q_SYNC
-
Update the on-disk copy of quota usages for a file system.
If
special
is NULL, then all file systems with active quotas are sync'ed.
The
addr
and
id
arguments are ignored.
- Q_GETSTATS
-
Get statistics and other generic information about the quota subsystem.
The
addr
argument should be a pointer to a
dqstats
structure in which data should be stored.
This structure is defined in
<sys/quota.h>.
The
special
and
id
arguments are ignored.
This operation is obsolete and not supported by recent kernels.
Files in
/proc/sys/fs/quota/
carry the information instead.
For XFS file systems making use of the XFS Quota Manager (XQM),
the above commands are bypassed and the following commands are used:
- Q_XQUOTAON
-
Turn on quotas for an XFS file system.
XFS provides the ability to turn on/off quota limit enforcement
with quota accounting.
Therefore, XFS expects
addr
to be a pointer to an
unsigned int
that contains either the flags
XFS_QUOTA_UDQ_ACCT
and/or
XFS_QUOTA_UDQ_ENFD
(for user quota), or
XFS_QUOTA_GDQ_ACCT
and/or
XFS_QUOTA_GDQ_ENFD
(for group quota), as defined in
<xfs/xqm.h>.
This operation requires privilege
(CAP_SYS_ADMIN).
- Q_XQUOTAOFF
-
Turn off quotas for an XFS file system.
As with
Q_QUOTAON,
XFS file systems expect a pointer to an
unsigned int
that specifies whether quota accounting and/or limit enforcement need
to be turned off.
This operation requires privilege
(CAP_SYS_ADMIN).
- Q_XGETQUOTA
-
Get disk quota limits and current usage for user
id.
The
addr
argument is a pointer to an
fs_disk_quota
structure (defined in
<xfs/xqm.h>).
Unprivileged users may retrieve only their own quotas;
a privileged user
(CAP_SYS_ADMIN)
may retrieve the quotas of any user.
- Q_XSETQLIM
-
Set disk quota limits for user
id.
The
addr
argument is a pointer to an
fs_disk_quota
structure (defined in
<xfs/xqm.h>).
This operation requires privilege
(CAP_SYS_ADMIN).
- Q_XGETQSTAT
-
Returns an
fs_quota_stat
structure containing XFS file system specific quota information.
This is useful for finding out how much space is used to store quota
information, and also to get quotaon/off status of a given local XFS
file system.
- Q_XQUOTARM
-
Free the disk space taken by disk quotas.
Quotas must have already been turned off.
There is no command equivalent to
Q_SYNC
for XFS since
sync(1)
writes quota information to disk (in addition to the other file system
metadata that it writes out).
RETURN VALUES
On success,
quotactl()
returns 0; on error -1
is returned, and
errno
is set to indicate the error.
ERRORS
- EFAULT
-
addr
or
special
is invalid.
- EINVAL
-
cmd
or
type
is invalid.
- ENOENT
-
The file specified by
special
or
addr
does not exist.
- ENOSYS
-
The kernel has not been compiled with the
CONFIG_QUOTA
option.
- ENOTBLK
-
special
is not a block device.
- EPERM
-
The caller lacked the required privilege
(CAP_SYS_ADMIN)
for the specified operation.
- ESRCH
-
No disk quota is found for the indicated user.
Quotas have not been turned on for this file system.
If
cmd
is
Q_SETQUOTA,
quotactl()
may also set
errno
to:
- ERANGE
-
Specified limits are out of range allowed by quota format.
If
cmd
is
Q_QUOTAON,
quotactl()
may also set
errno
to:
- EACCES
-
The quota file pointed to by
addr
exists, but is not a regular file; or,
the quota file pointed to by
addr
exists, but is not on the file system pointed to by
special.
- EBUSY
-
Q_QUOTAON
attempted, but another
Q_QUOTAON
had already been performed.
- EINVAL
-
The quota file is corrupted.
- ESRCH
-
Specified quota format was not found.
SEE ALSO
quota(1),
getrlimit(2),
quotacheck(8),
quotaon(8)
COLOPHON
This page is part of release 3.27 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUES
-
- ERRORS
-
- SEE ALSO
-
- COLOPHON
-
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Time: 07:34:56 GMT, March 26, 2013