Ubuntu Manpage: ioctl_xfs_fsgeometry - report XFS filesystem layout and features

Provided by: xfslibs-dev_6.8.0-2.2ubuntu1_amd64

NAME

       ioctl_xfs_fsgeometry - report XFS filesystem layout and features

SYNOPSIS

       #include <xfs/xfs_fs.h>

       int ioctl(int fd, XFS_IOC_FSGEOMETRY, struct xfs_fsop_geom *arg);
       int ioctl(int fd, XFS_IOC_FSGEOMETRY_V4, struct xfs_fsop_geom_v4 *arg);
       int ioctl(int fd, XFS_IOC_FSGEOMETRY_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;
/* struct xfs_fsop_geom_v4 stops here. */

__u32 sick;
__u32 checked;
__u64 reserved[17];
};

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.

The fields sick and checked indicate the relative health of various whole-filesystem
metadata. Please see the section XFS METADATA HEALTH REPORTING for more details.

reserved is set to zero.

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.

XFS METADATA HEALTH REPORTING

       The  online  filesystem  checking  utility scans metadata and records what it finds in the
       kernel incore state.  The following scheme is used for userspace to read the incore health
       status of the filesystem:

       • If a given sick flag is set in sick, then that piece of metadata has been observed to be
         damaged.  The same bit should be set in checked.

       • If a given sick flag is set in checked but is not  set  in  sick,  then  that  piece  of
         metadata has been checked and is not faulty.

       • If a given sick flag is not set in checked, then no conclusion can be made.

       The following flags apply to these fields:

           XFS_FSOP_GEOM_SICK_COUNTERS
                  Inode and space summary counters.

           XFS_FSOP_GEOM_SICK_UQUOTA
                  User quota information.

           XFS_FSOP_GEOM_SICK_GQUOTA
                  Group quota information.

           XFS_FSOP_GEOM_SICK_PQUOTA
                  Project quota information.

           XFS_FSOP_GEOM_SICK_RT_BITMAP
                  Free space bitmap for the realtime device.

           XFS_FSOP_GEOM_SICK_RT_SUMMARY
                  Free space summary for the realtime device.

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.