Linux / Unix Command: quotactl

Command Library

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, 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 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 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 information 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 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 superuser.

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 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 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)

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