NAME

ioctl_xfs_inumbers - query allocation information for groups of XFS inodes

SYNOPSIS

#include <xfs/xfs_fs.h>

int ioctl(int fd, XFS_IOC_INUMBERS, struct xfs_inumbers_req *arg);

DESCRIPTION

Query inode allocation information for groups of XFS inodes. This ioctl uses struct xfs_inumbers_req to set up a bulk transfer from the kernel:

struct xfs_inumbers_req {
	struct xfs_bulk_ireq    hdr;
	struct xfs_inumbers     inumbers[];
};

See below for the xfs_inumbers structure definition.

struct xfs_bulk_ireq {
	uint64_t                ino;
	uint32_t                flags;
	uint32_t                icount;
	uint32_t                ocount;
	uint32_t                agno;
	uint64_t                reserved[5];
};

hdr describes the information to query. The layout and behavior are documented in the ioctl_xfs_bulkstat(2) manpage and will not be discussed further here.

inumbers is an array of struct xfs_inumbers which is described below. The array must have at least icount elements.

struct xfs_inumbers {
	uint64_t                xi_startino;
	uint64_t                xi_allocmask;
	uint8_t                 xi_alloccount;
	uint8_t                 xi_version;
	uint8_t                 xi_padding[6];
};

This structure describes inode usage information for a group of 64 consecutive inode numbers.

xi_startino is the first inode number of this group.

xi_allocmask is a bitmask telling which inodes in this group are allocated. To clarify, bit N is set if inode xi_startino+N is allocated.

xi_alloccount is the number of inodes in this group that are allocated. This should be equal to popcnt(xi_allocmask).

xi_version is the version of this data structure. This will be set to XFS_INUMBERS_VERSION_V5 by the kernel.

xi_padding[6] is zeroed.

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.
EINVAL: One of the arguments was not valid.
EIO: An I/O error was encountered while performing the query.
ENOMEM: There was insufficient memory to perform the query.

CONFORMING TO

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