| NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | COLOPHON | The Linux Programming Interface |
QUOTACTL(2) Linux Programmer's Manual QUOTACTL(2)
quotactl - manipulate disk quotas
#include <sys/quota.h>
#include <xfs/xqm.h>
int quotactl(int cmd, const char *special, int id, caddr_t addr);
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).
On success, quotactl() returns 0; on error -1 is returned, and errno is set to
indicate the error.
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.
quota(1), getrlimit(2), quotacheck(8), quotaon(8)
This page is part of release 3.32 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/.
Linux 2010-06-16 QUOTACTL(2)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface