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 following 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 filesystem.
- EIO
An I/O error was encountered while performing the query.
Conforming to
This API is specific to XFS filesystem on the Linux kernel.