/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
/*
 * FS_IOC_GETFSMAP ioctl infrastructure.
 *
 * Copyright (C) 2017 Oracle.  All Rights Reserved.
 *
 * Author: Darrick J. Wong <darrick.wong@oracle.com>
 */
#ifndef _LINUX_FSMAP_H
#define _LINUX_FSMAP_H

#include <linux/types.h>

/*
 *      Structure for FS_IOC_GETFSMAP.
 *
 *      The memory layout for this call are the scalar values defined in
 *      struct fsmap_head, followed by two struct fsmap that describe
 *      the lower and upper bound of mappings to return, followed by an
 *      array of struct fsmap mappings.
 *
 *      fmh_iflags control the output of the call, whereas fmh_oflags report
 *      on the overall record output.  fmh_count should be set to the
 *      length of the fmh_recs array, and fmh_entries will be set to the
 *      number of entries filled out during each call.  If fmh_count is
 *      zero, the number of reverse mappings will be returned in
 *      fmh_entries, though no mappings will be returned.  fmh_reserved
 *      must be set to zero.
 *
 *      The two elements in the fmh_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 fsmap_head.fmh_recs[fsmap_head.fmh_count - 1] should be
 *      copied into fmh_keys[0] to have the kernel start where it left off.
 *
 *      The second element in the fmh_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
 *      fmh_recs.
 *
 *      fmr_device can be either a 32-bit cookie representing a device, or
 *      a 32-bit dev_t if the FMH_OF_DEV_T flag is set.  fmr_physical,
 *      fmr_offset, and fmr_length are expressed in units of bytes.
 *      fmr_owner is either an inode number, or a special value if
 *      FMR_OF_SPECIAL_OWNER is set in fmr_flags.
 */
struct fsmap {
        __u32           fmr_device;     /* device id */
        __u32           fmr_flags;      /* mapping flags */
        __u64           fmr_physical;   /* device offset of segment */
        __u64           fmr_owner;      /* owner id */
        __u64           fmr_offset;     /* file offset of segment */
        __u64           fmr_length;     /* length of segment */
        __u64           fmr_reserved[3];        /* must be zero */
};

struct fsmap_head {
        __u32           fmh_iflags;     /* control flags */
        __u32           fmh_oflags;     /* output flags */
        __u32           fmh_count;      /* # of entries in array incl. input */
        __u32           fmh_entries;    /* # of entries filled in (output). */
        __u64           fmh_reserved[6];        /* must be zero */

        struct fsmap    fmh_keys[2];    /* low and high keys for the mapping search */
        struct fsmap    fmh_recs[];     /* returned records */
};

/* Size of an fsmap_head with room for nr records. */
static inline __kernel_size_t
fsmap_sizeof(
        unsigned int    nr)
{
        return sizeof(struct fsmap_head) + nr * sizeof(struct fsmap);
}

/* Start the next fsmap query at the end of the current query results. */
static inline void
fsmap_advance(
        struct fsmap_head       *head)
{
        head->fmh_keys[0] = head->fmh_recs[head->fmh_entries - 1];
}

/*      fmh_iflags values - set by FS_IOC_GETFSMAP caller in the header. */
/* no flags defined yet */
#define FMH_IF_VALID            0

/*      fmh_oflags values - returned in the header segment only. */
#define FMH_OF_DEV_T            0x1     /* fmr_device values will be dev_t */

/*      fmr_flags values - returned for each non-header segment */
#define FMR_OF_PREALLOC         0x1     /* segment = unwritten pre-allocation */
#define FMR_OF_ATTR_FORK        0x2     /* segment = attribute fork */
#define FMR_OF_EXTENT_MAP       0x4     /* segment = extent map */
#define FMR_OF_SHARED           0x8     /* segment = shared with another file */
#define FMR_OF_SPECIAL_OWNER    0x10    /* owner is a special value */
#define FMR_OF_LAST             0x20    /* segment is the last in the dataset */

/* Each FS gets to define its own special owner codes. */
#define FMR_OWNER(type, code)   (((__u64)type << 32) | \
                                 ((__u64)code & 0xFFFFFFFFULL))
#define FMR_OWNER_TYPE(owner)   ((__u32)((__u64)owner >> 32))
#define FMR_OWNER_CODE(owner)   ((__u32)(((__u64)owner & 0xFFFFFFFFULL)))
#define FMR_OWN_FREE            FMR_OWNER(0, 1) /* free space */
#define FMR_OWN_UNKNOWN         FMR_OWNER(0, 2) /* unknown owner */
#define FMR_OWN_METADATA        FMR_OWNER(0, 3) /* metadata */

#define FS_IOC_GETFSMAP         _IOWR('X', 59, struct fsmap_head)

#endif /* _LINUX_FSMAP_H */