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/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
/*
* FS_IOC_GETFSREFCOUNTS ioctl infrastructure.
*
* Copyright (C) 2022 Oracle. All Rights Reserved.
*
* Author: Darrick J. Wong <djwong@kernel.org>
*/
#ifndef _LINUX_FSREFCOUNTS_H
#define _LINUX_FSREFCOUNTS_H
#include <linux/types.h>
/*
* Structure for FS_IOC_GETFSREFCOUNTS.
*
* The memory layout for this call are the scalar values defined in
* struct fsrefs_head, followed by two struct fsrefs that describe the
* lower and upper bound of mappings to return, followed by an array of
* struct fsrefs mappings.
*
* fch_iflags control the output of the call, whereas fch_oflags report
* on the overall record output. fch_count should be set to the length
* of the fch_recs array, and fch_entries will be set to the number of
* entries filled out during each call. If fch_count is zero, the number
* of refcount mappings will be returned in fch_entries, though no
* mappings will be returned. fch_reserved must be set to zero.
*
* The two elements in the fch_keys array are used to constrain the
* output. The first element in the array should represent the lowest
* disk mapping ("low key") that the user wants to learn about. If this
* value is all zeroes, the filesystem will return the first entry it
* knows about. For a subsequent call, the contents of
* fsrefs_head.fch_recs[fsrefs_head.fch_count - 1] should be copied into
* fch_keys[0] to have the kernel start where it left off.
*
* The second element in the fch_keys array should represent the highest
* disk mapping ("high key") that the user wants to learn about. If this
* value is all ones, the filesystem will not stop until it runs out of
* mapping to return or runs out of space in fch_recs.
*
* fcr_device can be either a 32-bit cookie representing a device, or a
* 32-bit dev_t if the FCH_OF_DEV_T flag is set. fcr_physical and
* fcr_length are expressed in units of bytes. fcr_owners is the number
* of owners.
*/
struct fsrefs {
__u32 fcr_device; /* device id */
__u32 fcr_flags; /* mapping flags */
__u64 fcr_physical; /* device offset of segment */
__u64 fcr_owners; /* number of owners */
__u64 fcr_length; /* length of segment */
__u64 fcr_reserved[4]; /* must be zero */
};
struct fsrefs_head {
__u32 fch_iflags; /* control flags */
__u32 fch_oflags; /* output flags */
__u32 fch_count; /* # of entries in array incl. input */
__u32 fch_entries; /* # of entries filled in (output). */
__u64 fch_reserved[6]; /* must be zero */
struct fsrefs fch_keys[2]; /* low and high keys for the mapping search */
struct fsrefs fch_recs[]; /* returned records */
};
/* Size of an fsrefs_head with room for nr records. */
static inline unsigned long long
fsrefs_sizeof(
unsigned int nr)
{
return sizeof(struct fsrefs_head) + nr * sizeof(struct fsrefs);
}
/* Start the next fsrefs query at the end of the current query results. */
static inline void
fsrefs_advance(
struct fsrefs_head *head)
{
head->fch_keys[0] = head->fch_recs[head->fch_entries - 1];
}
/* fch_iflags values - set by FS_IOC_GETFSREFCOUNTS caller in the header. */
/* no flags defined yet */
#define FCH_IF_VALID 0
/* fch_oflags values - returned in the header segment only. */
#define FCH_OF_DEV_T 0x1 /* fcr_device values will be dev_t */
/* fcr_flags values - returned for each non-header segment */
#define FCR_OF_LAST (1U << 0) /* segment is the last in the dataset */
/* XXX stealing XFS_IOC_GETBIOSIZE */
#define FS_IOC_GETFSREFCOUNTS _IOWR('X', 47, struct fsrefs_head)
#endif /* _LINUX_FSREFCOUNTS_H */
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