man2/quotactl.2

.\" Copyright (c) 2010, Jan Kara
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.TH QUOTACTL 2 2010-06-16 "Linux" "Linux Programmer's Manual"
.SH NAME
quotactl \- manipulate disk quotas
.SH SYNOPSIS
.nf
.B #include <sys/quota.h>
.B #include <xfs/xqm.h>
.LP
.BI "int quotactl(int " cmd ", const char *" special ", int " id \
", caddr_t " addr );
.fi
.SH DESCRIPTION
.LP
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
.BR quotactl ()
call manipulates disk quotas.
The
.I cmd
argument indicates a command to be applied to the user or
group ID specified in
.IR id .
To initialize the
.IR cmd
argument, use the
.IR "QCMD(subcmd, type)"
macro.
The
.I type
value is either
.BR USRQUOTA ,
for user quotas,
or
.BR GRPQUOTA ,
for group quotas.
The
.I subcmd
value is described below.

The
.I 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
.I addr
argument is the address of an optional, command-specific, data structure
that is copied in or out of the system.
The interpretation of
.I addr
is given with each command below.

The
.I subcmd
value is one of the following:
.TP 8
.B Q_QUOTAON
Turn on quotas for a file system.
The
.I id
argument is the identification number of the quota format to be used.
Currently, there are three supported quota formats:
.RS
.TP 13
.BR QFMT_VFS_OLD
The original quota format.
.TP
.BR 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.
.TP
.BR 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.
.RE
.IP
The
.IR 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
.BR quotacheck (8)
program.
This operation requires privilege
.RB ( CAP_SYS_ADMIN ).
.TP 8
.B Q_QUOTAOFF
Turn off quotas for a file system.
The
.I addr
and
.I id
arguments are ignored.
This operation requires privilege
.RB ( CAP_SYS_ADMIN ).
.TP
.B Q_GETQUOTA
Get disk quota limits and current usage for user or group
.IR id .
The
.I addr
argument is a pointer to a
.I dqblk
structure defined in
.IR <sys/quota.h>
as follows:
.in +4n
.nf

/* 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)

.fi
.in
The
.I dqb_valid
field is a bit mask that is set to indicate the entries in the
.I dqblk
structure that are valid.
Currently, the kernel fills in all entries of the
.I dqblk
structure and marks them as valid in the
.I dqb_valid
field.
Unprivileged users may retrieve only their own quotas;
a privileged user
.RB ( CAP_SYS_ADMIN )
can retrieve the quotas of any user.
.TP
.B Q_SETQUOTA
Set quota information for user or group
.IR id ,
using the information supplied in the
.I dqblk
structure pointed to by
.IR addr .
The
.I dqb_valid
field of the
.I dqblk
structure indicates which entries in the structure have been set by the caller.
This operation supersedes the
.B Q_SETQLIM
and
.B Q_SETUSE
operations in the previous quota interfaces.
This operation requires privilege
.RB ( CAP_SYS_ADMIN ).
.TP
.B Q_GETINFO
Get information (like grace times) about quotafile.
The
.I addr
argument should be a pointer to a
.I dqinfo
structure.
This structure is defined in
.IR <sys/quota.h>
as follows:
.in +4n
.nf

/* 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)

.fi
.in
The
.I dqi_valid
field in the
.I dqinfo
structure indicates the entries in the structure that are valid.
Currently, the kernel fills in all entries of the
.I dqinfo
structure and marks them all as valid in the
.I dqi_valid
field.
The
.I id
argument is ignored.
.TP
.B Q_SETINFO
Set information about quotafile.
The
.I addr
argument should be a pointer to a
.I dqinfo
structure.
The
.I dqi_valid
field of the
.I dqinfo
structure indicates the entries in the structure
that have been set by the caller.
This operation supersedes the
.B Q_SETGRACE
and
.B Q_SETFLAGS
operations in the previous quota interfaces.
The
.I id
argument is ignored.
This operation requires privilege
.RB ( CAP_SYS_ADMIN ).
.TP
.B Q_GETFMT
Get quota format used on the specified file system.
The
.I addr
argument should be a pointer to a 4-byte buffer
where the format number will be stored.
.TP
.B Q_SYNC
Update the on-disk copy of quota usages for a file system.
If
.I special
is NULL, then all file systems with active quotas are sync'ed.
The
.I addr
and
.I id
arguments are ignored.
.TP
.B Q_GETSTATS
Get statistics and other generic information about the quota subsystem.
The
.I addr
argument should be a pointer to a
.I dqstats
structure in which data should be stored.
This structure is defined in
.IR <sys/quota.h>.
The
.I special
and
.I id
arguments are ignored.
This operation is obsolete and not supported by recent kernels.
.\" Q_GETSTATS was removed in kernel 2.4.22.
Files in
.I /proc/sys/fs/quota/
carry the information instead.
.PP
For XFS file systems making use of the XFS Quota Manager (XQM),
the above commands are bypassed and the following commands are used:
.TP 8
.B 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
.I addr
to be a pointer to an
.I "unsigned int"
that contains either the flags
.B XFS_QUOTA_UDQ_ACCT
and/or
.B XFS_QUOTA_UDQ_ENFD
(for user quota), or
.B XFS_QUOTA_GDQ_ACCT
and/or
.B XFS_QUOTA_GDQ_ENFD
(for group quota), as defined in
.IR <xfs/xqm.h> .
This operation requires privilege
.RB ( CAP_SYS_ADMIN ).
.TP
.B Q_XQUOTAOFF
Turn off quotas for an XFS file system.
As with
.BR Q_QUOTAON ,
XFS file systems expect a pointer to an
.I "unsigned int"
that specifies whether quota accounting and/or limit enforcement need
to be turned off.
This operation requires privilege
.RB ( CAP_SYS_ADMIN ).
.TP
.B Q_XGETQUOTA
Get disk quota limits and current usage for user
.IR id .
The
.I addr
argument is a pointer to an
.I fs_disk_quota
structure (defined in
.IR <xfs/xqm.h> ).
Unprivileged users may retrieve only their own quotas;
a privileged user
.RB ( CAP_SYS_ADMIN )
may retrieve the quotas of any user.
.TP
.B Q_XSETQLIM
Set disk quota limits for user
.IR id .
The
.I addr
argument is a pointer to an
.I fs_disk_quota
structure (defined in
.IR <xfs/xqm.h> ).
This operation requires privilege
.RB ( CAP_SYS_ADMIN ).
.TP
.B Q_XGETQSTAT
Returns an
.I 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.
.TP
.B Q_XQUOTARM
Free the disk space taken by disk quotas.
Quotas must have already been turned off.
.PP
There is no command equivalent to
.B Q_SYNC
for XFS since
.BR sync (1)
writes quota information to disk (in addition to the other file system
metadata that it writes out).
.SH RETURN VALUES
.LP
On success,
.BR quotactl ()
returns 0; on error \-1
is returned, and
.I errno
is set to indicate the error.
.SH ERRORS
.TP
.B EFAULT
.I addr
or
.I special
is invalid.
.TP
.B EINVAL
.I cmd
or
.I type
is invalid.
.TP
.B ENOENT
The file specified by
.I special
or
.I addr
does not exist.
.TP
.B ENOSYS
The kernel has not been compiled with the
.B CONFIG_QUOTA
option.
.TP
.B ENOTBLK
.I special
is not a block device.
.TP
.B EPERM
The caller lacked the required privilege
.RB ( CAP_SYS_ADMIN )
for the specified operation.
.TP
.B ESRCH
No disk quota is found for the indicated user.
Quotas have not been turned on for this file system.
.LP
If
.I cmd
is
.BR Q_SETQUOTA ,
.BR quotactl ()
may also set
.I errno
to:
.TP
.B ERANGE
Specified limits are out of range allowed by quota format.
.LP
If
.I cmd
is
.BR Q_QUOTAON ,
.BR quotactl ()
may also set
.I errno
to:
.TP
.B EACCES
The quota file pointed to by
.I addr
exists, but is not a regular file; or,
the quota file pointed to by
.I addr
exists, but is not on the file system pointed to by
.IR special .
.TP
.B EBUSY
.B Q_QUOTAON
attempted, but another
.B Q_QUOTAON
had already been performed.
.TP
.B EINVAL
The quota file is corrupted.
.TP
.B ESRCH
Specified quota format was not found.
.SH "SEE ALSO"
.BR quota (1),
.BR getrlimit (2),
.BR quotacheck (8),
.BR quotaon (8)