LXR linux/include/uapi/linux/fsmap.h

   1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
   2/*
   3 * FS_IOC_GETFSMAP ioctl infrastructure.
   4 *
   5 * Copyright (C) 2017 Oracle.  All Rights Reserved.
   6 *
   7 * Author: Darrick J. Wong <darrick.wong@oracle.com>
   8 */
   9#ifndef _LINUX_FSMAP_H
  10#define _LINUX_FSMAP_H
  11
  12#include <linux/types.h>
  13
  14/*
  15 *      Structure for FS_IOC_GETFSMAP.
  16 *
  17 *      The memory layout for this call are the scalar values defined in
  18 *      struct fsmap_head, followed by two struct fsmap that describe
  19 *      the lower and upper bound of mappings to return, followed by an
  20 *      array of struct fsmap mappings.
  21 *
  22 *      fmh_iflags control the output of the call, whereas fmh_oflags report
  23 *      on the overall record output.  fmh_count should be set to the
  24 *      length of the fmh_recs array, and fmh_entries will be set to the
  25 *      number of entries filled out during each call.  If fmh_count is
  26 *      zero, the number of reverse mappings will be returned in
  27 *      fmh_entries, though no mappings will be returned.  fmh_reserved
  28 *      must be set to zero.
  29 *
  30 *      The two elements in the fmh_keys array are used to constrain the
  31 *      output.  The first element in the array should represent the
  32 *      lowest disk mapping ("low key") that the user wants to learn
  33 *      about.  If this value is all zeroes, the filesystem will return
  34 *      the first entry it knows about.  For a subsequent call, the
  35 *      contents of fsmap_head.fmh_recs[fsmap_head.fmh_count - 1] should be
  36 *      copied into fmh_keys[0] to have the kernel start where it left off.
  37 *
  38 *      The second element in the fmh_keys array should represent the
  39 *      highest disk mapping ("high key") that the user wants to learn
  40 *      about.  If this value is all ones, the filesystem will not stop
  41 *      until it runs out of mapping to return or runs out of space in
  42 *      fmh_recs.
  43 *
  44 *      fmr_device can be either a 32-bit cookie representing a device, or
  45 *      a 32-bit dev_t if the FMH_OF_DEV_T flag is set.  fmr_physical,
  46 *      fmr_offset, and fmr_length are expressed in units of bytes.
  47 *      fmr_owner is either an inode number, or a special value if
  48 *      FMR_OF_SPECIAL_OWNER is set in fmr_flags.
  49 */
  50struct fsmap {
  51        __u32           fmr_device;     /* device id */
  52        __u32           fmr_flags;      /* mapping flags */
  53        __u64           fmr_physical;   /* device offset of segment */
  54        __u64           fmr_owner;      /* owner id */
  55        __u64           fmr_offset;     /* file offset of segment */
  56        __u64           fmr_length;     /* length of segment */
  57        __u64           fmr_reserved[3];        /* must be zero */
  58};
  59
  60struct fsmap_head {
  61        __u32           fmh_iflags;     /* control flags */
  62        __u32           fmh_oflags;     /* output flags */
  63        __u32           fmh_count;      /* # of entries in array incl. input */
  64        __u32           fmh_entries;    /* # of entries filled in (output). */
  65        __u64           fmh_reserved[6];        /* must be zero */
  66
  67        struct fsmap    fmh_keys[2];    /* low and high keys for the mapping search */
  68        struct fsmap    fmh_recs[];     /* returned records */
  69};
  70
  71/* Size of an fsmap_head with room for nr records. */
  72static inline size_t
  73fsmap_sizeof(
  74        unsigned int    nr)
  75{
  76        return sizeof(struct fsmap_head) + nr * sizeof(struct fsmap);
  77}
  78
  79/* Start the next fsmap query at the end of the current query results. */
  80static inline void
  81fsmap_advance(
  82        struct fsmap_head       *head)
  83{
  84        head->fmh_keys[0] = head->fmh_recs[head->fmh_entries - 1];
  85}
  86
  87/*      fmh_iflags values - set by FS_IOC_GETFSMAP caller in the header. */
  88/* no flags defined yet */
  89#define FMH_IF_VALID            0
  90
  91/*      fmh_oflags values - returned in the header segment only. */
  92#define FMH_OF_DEV_T            0x1     /* fmr_device values will be dev_t */
  93
  94/*      fmr_flags values - returned for each non-header segment */
  95#define FMR_OF_PREALLOC         0x1     /* segment = unwritten pre-allocation */
  96#define FMR_OF_ATTR_FORK        0x2     /* segment = attribute fork */
  97#define FMR_OF_EXTENT_MAP       0x4     /* segment = extent map */
  98#define FMR_OF_SHARED           0x8     /* segment = shared with another file */
  99#define FMR_OF_SPECIAL_OWNER    0x10    /* owner is a special value */
 100#define FMR_OF_LAST             0x20    /* segment is the last in the dataset */
 101
 102/* Each FS gets to define its own special owner codes. */
 103#define FMR_OWNER(type, code)   (((__u64)type << 32) | \
 104                                 ((__u64)code & 0xFFFFFFFFULL))
 105#define FMR_OWNER_TYPE(owner)   ((__u32)((__u64)owner >> 32))
 106#define FMR_OWNER_CODE(owner)   ((__u32)(((__u64)owner & 0xFFFFFFFFULL)))
 107#define FMR_OWN_FREE            FMR_OWNER(0, 1) /* free space */
 108#define FMR_OWN_UNKNOWN         FMR_OWNER(0, 2) /* unknown owner */
 109#define FMR_OWN_METADATA        FMR_OWNER(0, 3) /* metadata */
 110
 111#define FS_IOC_GETFSMAP         _IOWR('X', 59, struct fsmap_head)
 112
 113#endif /* _LINUX_FSMAP_H */
 114