NAME

ioctl_xfs_fsinumbers - extract a list of valid inode numbers from an XFS filesystem

SYNOPSIS

#include <xfs/xfs_fs.h>

int ioctl(int fd, XFS_IOC_FSINUMBERS, struct xfs_fsop_bulkreq *arg);

DESCRIPTION

Queries inode allocation information from an XFS filesystem. It is intended to be called iteratively to obtain the entire set of inodes. These ioctls use struct xfs_fsop_bulkreq to set up a bulk transfer with the kernel:

struct xfs_fsop_bulkreq {
	__u64   *lastip;
	__s32   count;
	void    *ubuffer;
	__s32   *ocount;
};

lastip points to a value that will receive the number of the "last inode." This should be set to one less than the number of the first inode for which the caller wants information, or zero to start with the first inode in the filesystem. After the call, this value will be set to the number of the last inode for which information is supplied. This field will not be updated if ocount is NULL.

count is the number of elements in the ubuffer array and therefore the number of inode groups for which to return allocation information.

ocount points to a value that will receive the number of records returned. An output value of zero means that there are no more inode groups left to enumerate. If this value is NULL, then neither ocount nor lastip will be updated.

ubuffer points to a memory buffer where inode group information will be copied. This buffer must be an array of struct xfs_inogrp which is described below. The array must have at least count elements.

struct xfs_inogrp {
	__u64   xi_startino;
	__s32   xi_alloccount;
	__u64   xi_allocmask;
}

This structure describes inode usage information for a group of 64 consecutive inode numbers. The fields are as follows:

xi_startino is the first inode number of this group.

xi_alloccount is the number of bits that are set in xi_allocmask. This is the number of inodes allocated in this group.

xi_allocmask is a bitmask of inodes that are allocated in this inode group. The bitmask is 64 bits long, and the least significant bit corresponds to inode xi_startino.

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.