IOCTL-XFS-AG-GEOMETRY(2)       System Calls Manual	IOCTL-XFS-AG-GEOMETRY(2)

NAME
     ioctl_xfs_ag_geometry - query XFS allocation group geometry information

SYNOPSIS
     #include <xfs/xfs_fs.h>

     int ioctl(int fd, XFS_IOC_AG_GEOMETRY, struct xfs_ag_geometry *arg);

DESCRIPTION
     This  XFS	ioctl  retrieves the geometry information for a given allocation
     group.  The geometry information is conveyed in a structure of the	 follow-
     ing form:

	 struct xfs_ag_geometry {
	      uint32_t	ag_number;
	      uint32_t	ag_length;
	      uint32_t	ag_freeblks;
	      uint32_t	ag_icount;
	      uint32_t	ag_ifree;
	      uint32_t	ag_sick;
	      uint32_t	ag_checked;
	      uint32_t	ag_flags;
	      uint64_t	ag_reserved[12];
	 };

     ag_number
	    The	 caller must set this field to the index of the allocation group
	    that the caller wishes to learn about.

     ag_length
	    The length of the allocation group is returned  in	this  field,  in
	    units of filesystem blocks.

     ag_freeblks
	    The	 number	 of  free  blocks in the allocation group is returned in
	    this field, in units of filesystem blocks.

     ag_icount
	    The number of inode records allocated in this  allocation  group  is
	    returned in this field.

     ag_ifree
	    The	 number of unused inode records (of the space allocated) in this
	    allocation group is returned in this field.

     ag_flags
	    The caller can set this field to change the operational behavior  of
	    the	 ioctl.	  Currently  no flags are defined, so this field must be
	    zero.

     ag_reserved
	    All reserved fields will be set to zero on return.

     The fields ag_sick and ag_checked indicate the relative health  of	 various
     allocation group metadata:

     * If  a  given sick flag is set in ag_sick, then that piece of metadata has
       been observed to be damaged.  The same bit will be set in ag_checked.

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

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

     The following flags apply to these fields:

	 XFS_AG_GEOM_SICK_SB
		Allocation group superblock.

	 XFS_AG_GEOM_SICK_AGF
		Free space header.

	 XFS_AG_GEOM_SICK_AGFL
		Free space reserve list.

	 XFS_AG_GEOM_SICK_AGI
		Inode header.

	 XFS_AG_GEOM_SICK_BNOBT or XFS_AG_GEOM_SICK_CNTBT
		Free space btrees.

	 XFS_AG_GEOM_SICK_INOBT or XFS_AG_GEOM_SICK_FINOBT
		Inode btrees.

	 XFS_AG_GEOM_SICK_RMAPBT
		Reverse mapping btree.

	 XFS_AG_GEOM_SICK_REFCNTBT
		Reference count btree.

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:

     EFSBADCRC
	    Metadata checksum validation failed while performing the query.

     EFSCORRUPTED
	    Metadata corruption was encountered while performing the query.

     EINVAL
	    The specified allocation group number is not valid for this filesys-
	    tem.

     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)

XFS				   2019-08-30		IOCTL-XFS-AG-GEOMETRY(2)