IOCTL-XFS-FSOP-GEOMETRY(2)

NAME
ioctl_xfs_fsop_geometry - report XFS filesystem layout and features

SYNOPSIS
#include <xfs/xfs_fs.h>

int ioctl(int fd, XFS_IOC_FSOP_GEOMETRY, struct xfs_fsop_geom*arg);
int ioctl(int fd, XFS_IOC_FSOP_GEOMETRY_V1, struct xfs_fsop_geom_v1 *arg);

DESCRIPTION
Report the details of an XFS filesystem layout, features, and other descriptive items. This information is conveyed in a structure of the following form:

struct xfs_fsop_geom {
	__u32         blocksize;
	__u32         rtextsize;
	__u32         agblocks;
	__u32         agcount;
	__u32         logblocks;
	__u32         sectsize;
	__u32         inodesize;
	__u32         imaxpct;
	__u64         datablocks;
	__u64         rtblocks;
	__u64         rtextents;
	__u64         logstart;
	unsigned char uuid[16];
	__u32         sunit;
	__u32         swidth;
	__s32         version;
	__u32         flags;
	__u32         logsectsize;
	__u32         rtsectsize;
	__u32         dirblocksize;
	/* struct xfs_fsop_geom_v1 stops here. */
	__u32         logsunit;
};

blocksize is the size of a fundamental filesystem block, in bytes.

rtextsize is the size of an extent on the realtime volume, in bytes.

agblocks is the size of an allocation group, in units of filesystem blocks.

agcount is the number of allocation groups in the filesystem.

logblocks is the size of the log, in units of filesystem blocks.

sectsize is the smallest amount of data that can be written to the data device atomically, in bytes.

inodesize is the size of an inode record, in bytes.

imaxpct is the maximum percentage of the filesystem that can be allocated to inode record blocks.

datablocks is the size of the data device, in units of filesystem blocks.

rtblocks is the size of the realtime device, in units of filesystem blocks.

rtextents is the number of extents that can be allocated on the realtime device.

logstart is the start of the log, in units of filesystem blocks. If the filesystem has an external log, this will be zero.

uuid is the universal unique identifier of the filesystem.

sunit is what the filesystem has been told is the size of a RAID stripe unit on the underlying data device, in filesystem blocks.

swidth is what the filesystem has been told is the width of a RAID stripe on the underlying data device, in units of RAID stripe units.

version is the version of this structure. This value will be XFS_FSOP_GEOM_VERSION.

flags tell us what features are enabled on the filesystem. Refer to the section FILESYSTEM FEATURE FLAGS below for more information about each feature.

logsectsize is the smallest amount of data that can be written to the log device atomically, in bytes.

rtsectsize is the smallest amount of data that can be written to the realtime device atomically, in bytes.

dirblocksize is the size of directory blocks, in bytes.

logsunit is what the filesystem has been told is the size of a RAID stripe unit on the underlying log device, in filesystem blocks. This field is meaningful only if the flag XFS_FSOP_GEOM_FLAGS_LOGV2 is set.

FILESYSTEM FEATURE FLAGS
Filesystem features are reported to userspace as a combination the following flags:

XFS_FSOP_GEOM_FLAGS_ATTR
    Extended attributes are present.

XFS_FSOP_GEOM_FLAGS_NLINK
    Files on this filesystem support up to 2^32 hard links. If this flag is not set, files on this filesystem support only up to 2^16 hard links.

XFS_FSOP_GEOM_FLAGS_QUOTA
    Quotas are enabled.

XFS_FSOP_GEOM_FLAGS_IALIGN
    Inodes are aligned for better performance.

XFS_FSOP_GEOM_FLAGS_DALIGN
    Filesystem tries to align data block allocations to RAID stripe units for better performance.

XFS_FSOP_GEOM_FLAGS_SHARED
    Unused.

XFS_FSOP_GEOM_FLAGS_EXTFLG
    Filesystem supports unwritten extents.

XFS_FSOP_GEOM_FLAGS_DIRV2
    Directories are in version 2 format and maintain free space data for better performance. Version 1 format directories are no longer supported.

XFS_FSOP_GEOM_FLAGS_LOGV2
    Log uses the V2 format.

XFS_FSOP_GEOM_FLAGS_SECTOR
    The log device has a sector size larger than 512 bytes.

XFS_FSOP_GEOM_FLAGS_ATTR2
    Filesystem contains V2 extended attributes.

XFS_FSOP_GEOM_FLAGS_PROJID32
    Project IDs can be as large as 2^32. If this flag is not set, the filesystem supports only 2^16 project IDs.

XFS_FSOP_GEOM_FLAGS_DIRV2CI
    Case-insensitive lookups are supported on directories.

XFS_FSOP_GEOM_FLAGS_LAZYSB
    On-disk superblock counters are updated only at unmount time.

XFS_FSOP_GEOM_FLAGS_V5SB
    Metadata blocks are self describing and contain checksums.

XFS_FSOP_GEOM_FLAGS_FTYPE
    Directories contain inode types in directory entries.

XFS_FSOP_GEOM_FLAGS_FINOBT
    Filesystem maintains an index of free inodes.

XFS_FSOP_GEOM_FLAGS_SPINODES
    Filesystem may allocate discontiguous inode chunks when free space is fragmented.

XFS_FSOP_GEOM_FLAGS_RMAPBT
    Filesystem stores reverse mappings of blocks to owners.

XFS_FSOP_GEOM_FLAGS_REFLINK
    Filesystem supports sharing blocks between files.

RETURN VALUE
On error, -1 is returned, and errno is set to indicate the error.

ERRORS
Error codes can be one of, but are not limited to, the following:

EFAULT
    The kernel was not able to copy into the userspace buffer.

EFSBADCRC
    Metadata checksum validation failed while performing the query.

EFSCORRUPTED
    Metadata corruption was encountered while performing the query.

EIO An I/O error was encountered while performing the query.

CONFORMING TO
This API is specific to XFS filesystem on the Linux kernel.

SEE ALSO
ioctl(2)