NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | SEE ALSO | COLOPHON

QUOTACTL(2)               Linux Programmer's Manual              QUOTACTL(2)

NAME         top

       quotactl - manipulate disk quotas

SYNOPSIS         top

       #include <sys/quota.h>
       #include <xfs/xqm.h>

       int quotactl(int cmd, const char *special, int id, caddr_t addr);

DESCRIPTION         top

       The quota system can be used to set per-user and per-group limits on
       the amount of disk space used on a filesystem.  For each user and/or
       group, a soft limit and a hard limit can be set for each filesystem.
       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
       filesystem 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 filesystem.  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 filesystem.  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 filesystem.  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 occupied space
                                                     (in bytes) */
                       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_GETNEXTQUOTA (since Linux 4.6)
               This operation is the same as Q_GETQUOTA, but it returns
               quota information for the next ID greater than or equal to id
               that has a quota set.

               The addr argument is a pointer to a nextdqblk structure whose
               fields are as for the dqblk, except for the addition of a
               dqb_id field that is used to return the ID for which quota
               information is being returned:

                   struct nextdqblk {
                       uint64_t dqb_bhardlimit;
                       uint64_t dqb_bsoftlimit;
                       uint64_t dqb_curspace;
                       uint64_t dqb_ihardlimit;
                       uint64_t dqb_isoftlimit;
                       uint64_t dqb_curinodes;
                       uint64_t dqb_btime;
                       uint64_t dqb_itime;
                       uint32_t dqb_valid;
                       uint32_t dqb_id;
                   };

       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 (since Linux 2.4.22)
               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 (since Linux 2.4.22)
               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 (since Linux 2.4.22)
               Get quota format used on the specified filesystem.  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 filesystem.  If
               special is NULL, then all filesystems with active quotas are
               sync'ed.  The addr and id arguments are ignored.

       Q_GETSTATS (supported up to Linux 2.4.21)
               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 was removed in Linux 2.4.22.
               Files in /proc/sys/fs/quota/ carry the information instead.

       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 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 filesystem.  As with 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 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_XGETNEXTQUOTA (since Linux 4.6)
               This operation is the same as Q_XGETQUOTA, but it returns
               quota information for the next ID greater than or equal to id
               that has a quota set.

       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 filesystem-
               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 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 that it writes out).

RETURN VALUE         top

       On success, quotactl() returns 0; on error -1 is returned, and errno
       is set to indicate the error.

ERRORS         top

       EACCES cmd is Q_QUOTAON, and the quota file pointed to by addr
              exists, but is not a regular file or is not on the filesystem
              pointed to by special.

       EBUSY  cmd is Q_QUOTAON, but another Q_QUOTAON had already been
              performed.

       EFAULT addr or special is invalid.

       EINVAL cmd or type is invalid.

       EINVAL cmd is Q_QUOTAON, but the specified quota file is corrupted.

       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.

       ERANGE cmd is Q_SETQUOTA, but the specified limits are out of the
              range allowed by the quota format.

       ESRCH  No disk quota is found for the indicated user.  Quotas have
              not been turned on for this filesystem.

       ESRCH  cmd is Q_QUOTAON, but the specified quota format was not
              found.

       ESRCH  cmd is Q_GETNEXTQUOTA or Q_XGETNEXTQUOTA, but there is no ID
              greater than or equal to id that has an active quota.

SEE ALSO         top

       quota(1), getrlimit(2), quotacheck(8), quotaon(8)

COLOPHON         top

       This page is part of release 4.07 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

Linux                            2016-07-17                      QUOTACTL(2)