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 indi
cates 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,
command 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 filesystem. 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 him
self.
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.
a filesystem. 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 informa
tion about quota subsystem. addr should be
a pointer to dqstats structure (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 follow
ing 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 superuser.
in Q_QUOTAON, XFS filesystems expect a
pointer to an unsigned int that specifies
whether quota accounting and/or limit
enforcement 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 quotas 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 contain
ing XFS filesystem specific quota informa
tion. This is useful in finding out how
much space is spent to store quota informa
tion, 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.
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)
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