quotactl
QUOTACTL(2) QUOTACTL(2)
NAME
quotactl - manipulate disk quotas
SYNOPSIS
#include <linux/quota.h>
#include <linux/xqm.h>
long quotactl(int cmd, char *special, qid_t id, caddr_t addr)
DESCRIPTION
The quotactl() call manipulates disk quotas. cmd indicates a command
to be applied to UID id or GID id. To set the type of quota use the
QCMD(cmd, type) macro. special is a pointer to a null-terminated
string containing the path name of the block special device for the
filesystem being manipulated. addr is the address of an optional, com-
mand specific, data structure which is copied in or out of the system.
The interpretation of addr is given with each command below.
Q_QUOTAON Turn on quotas for a filesystem. addr points to the
path name of file containing the quotas for the filesys-
tem. The quota file must exist; it is normally created
with the quotacheck(8) program. This call is restricted
to the super-user.
Q_QUOTAOFF Turn off quotas for a filesystem. addr and id are
ignored. This call is restricted to the super-user.
Q_GETQUOTA Get disk quota limits and current usage for user or
group id. addr is a pointer to a mem_dqblk structure
(defined in <linux/quota.h>). Only the super-user may
get the quotas of a user other than himself.
Q_SETQUOTA Set disk quota limits and current usage for user or
group id. addr is a pointer to a mem_dqblk structure
(defined in <linux/quota.h>). This call is restricted
to the super-user.
Q_SETQLIM Set disk quota limits for user or group id. addr is a
pointer to a mem_dqblk structure (defined in
<linux/quota.h>). This call is restricted to the super-
user.
Q_SETUSE Set current usage for user or group id. addr is a
pointer to a mem_dqblk structure (defined in
<linux/quota.h>). This call is restricted to the super-
user.
Q_SYNC Update the on-disk copy of quota usages for a filesys-
tem. If special is null then all filesystems with
active quotas are sync'ed. addr and id are ignored.
Q_GETSTATS Get statistics and other generic information about quota
subsystem. addr should be a pointer to dqstats struc-
ture (defined in <linux/quota.h>) in which data should
be stored. special and id are ignored.
New quota format also allows following additional calls:
Q_GETINFO Get information (like grace times) about quotafile.
addr should be a pointer to mem_dqinfo structure
(defined in <linux/quota.h>). id is ignored.
Q_SETINFO Set information about quotafile. addr should be a
pointer to mem_dqinfo structure (defined in
<linux/quota.h>). id is ignored. This operation is
restricted to super-user.
Q_SETGRACE Set grace times in information about quotafile. addr
should be a pointer to mem_dqinfo structure (defined in
<linux/quota.h>). id is ignored. This operation is
restricted to super-user.
Q_SETFLAGS Set flags in information about quotafile. These flags
are defined in <linux/quota.h>. Note that there are
currently no defined flags. addr should be a pointer to
mem_dqinfo structure (defined in <linux/quota.h>). id
is ignored. This operation is restricted to super-user.
For XFS filesystems 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 filesystem. XFS provides the
ability to turn on/off quota limit enforcement with
quota accounting. Therefore, XFS expects the 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
<linux/xqm.h>. This call is restricted to the supe-
ruser.
Q_XQUOTAOFF Turn off quotas for an XFS filesystem. As in Q_QUOTAON,
XFS filesystems expect a pointer to an unsigned int that
specifies whether quota accounting and/or limit enforce-
ment need to be turned off. This call is restricted to
the superuser.
Q_XGETQUOTA Get disk quota limits and current usage for user id.
addr is a pointer to a fs_disk_quota structure (defined
in <linux/xqm.h>). Only the superuser may get the quo-
tas of a user other than himself.
Q_XSETQLIM Set disk quota limits for user id. addr is a pointer to
a fs_disk_quota structure (defined in <linux/xqm.h>).
This call is restricted to the superuser.
Q_XGETQSTAT Returns a fs_quota_stat structure containing XFS
filesystem specific quota information. This is useful
in finding out how much space is spent to store quota
information, and also to get quotaon/off status of a
given local XFS filesystem.
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 filesystem metadata
it writes out).
RETURN VALUES
quotactl() returns:
0 on success.
-1 on failure and sets errno to indicate the error.
ERRORS
EFAULT addr or special are invalid.
EINVAL The kernel has not been compiled with the QUOTA option.
cmd is invalid.
ENOENT The file specified by special or addr does not exist.
ENOTBLK special is not a block device.
EPERM The call is privileged and the caller was not the super-
user.
ESRCH No disc quota is found for the indicated user.
Quotas have not been turned on for this filesystem.
EUSERS The quota table is full.
If cmd is Q_QUOTAON, quotactl() may set errno to:
EACCES The quota file pointed to by addr exists but is not a
regular file.
The quota file pointed to by addr exists but is not on
the filesystem pointed to by special.
EBUSY Q_QUOTAON attempted while another Q_QUOTAON has already
taken place.
SEE ALSO
quota(1), getrlimit(2), quotacheck(8), quotaon(8)
QUOTACTL(2)
