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long quotactl(int cmd, char *special, int id, caddr_t addr)
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. id is the identifica-
tion number of the quota format to be used. Format num-
bers are defined in the header file of appropriate for-
mat. Currently there are two supported quota formats
whose numbers are defined by constants QFMT_VFS_OLD
(original quota format) and QFMT_VFS_V0 (new VFS v0
quota format). 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 quo-
tacheck(8) program. This call is restricted to the
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 an dqblk structure
(defined in <sys/quota.h>). The field dqb_valid defines
the entries in the structure which are set correctly. On
Q_GETQUOTA call all entries are valid. Only the super-
user may get the quotas of a user other than himself.
Q_SETQUOTA Set current quota information for user or group id.
addr is a pointer to an dqblk structure (defined in
<sys/quota.h>). The field dqb_valid defines which
entries in the quota structure are valid and should be
set. The constants for dqb_valid field are defined in
the <sys/quota.h> header file. This call obsoletes calls
Q_SETQLIM and Q_SETUSE in the previous quota interfaces.
This call is restricted to the super-user.
Q_GETINFO Get information (like grace times) about quotafile.
addr should be a pointer to an dqinfo structure (defined
in <sys/quota.h>). The dqi_valid field in the structure
defines entries in it which are valid. On Q_GETINFO call
all entries are valid. Parameter id is ignored.
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 <sys/quota.h>) in which data should be
stored. special and id are ignored.
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
<xfs/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 enforce-
ment need to be turned off. This call is restricted to
Q_XGETQUOTA Get disk quota limits and current usage for user id.
addr is a pointer to a fs_disk_quota structure (defined
in <xfs/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 <xfs/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).
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-
ESRCH No disc quota is found for the indicated user.
Quotas have not been turned on for this filesystem.
If cmd is Q_QUOTAON, quotactl() may set errno to:
EACCES The quota file pointed to by addr exists but is not a
The quota file pointed to by addr exists but is not on
the filesystem pointed to by special.
EINVAL The quota file is corrupted.
ESRCH Specified quota format was not found.
EBUSY Q_QUOTAON attempted while another Q_QUOTAON has already
quota(1), getrlimit(2), quotacheck(8), quotaon(8)