uapi/linux/fsmap.h

0001 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
0002 /*
0003  * FS_IOC_GETFSMAP ioctl infrastructure.
0004  *
0005  * Copyright (C) 2017 Oracle.  All Rights Reserved.
0006  *
0007  * Author: Darrick J. Wong <darrick.wong@oracle.com>
0008  */
0009 #ifndef _LINUX_FSMAP_H
0010 #define _LINUX_FSMAP_H
0011
0012 #include <linux/types.h>
0013
0014 /*
0015  *  Structure for FS_IOC_GETFSMAP.
0016  *
0017  *  The memory layout for this call are the scalar values defined in
0018  *  struct fsmap_head, followed by two struct fsmap that describe
0019  *  the lower and upper bound of mappings to return, followed by an
0020  *  array of struct fsmap mappings.
0021  *
0022  *  fmh_iflags control the output of the call, whereas fmh_oflags report
0023  *  on the overall record output.  fmh_count should be set to the
0024  *  length of the fmh_recs array, and fmh_entries will be set to the
0025  *  number of entries filled out during each call.  If fmh_count is
0026  *  zero, the number of reverse mappings will be returned in
0027  *  fmh_entries, though no mappings will be returned.  fmh_reserved
0028  *  must be set to zero.
0029  *
0030  *  The two elements in the fmh_keys array are used to constrain the
0031  *  output.  The first element in the array should represent the
0032  *  lowest disk mapping ("low key") that the user wants to learn
0033  *  about.  If this value is all zeroes, the filesystem will return
0034  *  the first entry it knows about.  For a subsequent call, the
0035  *  contents of fsmap_head.fmh_recs[fsmap_head.fmh_count - 1] should be
0036  *  copied into fmh_keys[0] to have the kernel start where it left off.
0037  *
0038  *  The second element in the fmh_keys array should represent the
0039  *  highest disk mapping ("high key") that the user wants to learn
0040  *  about.  If this value is all ones, the filesystem will not stop
0041  *  until it runs out of mapping to return or runs out of space in
0042  *  fmh_recs.
0043  *
0044  *  fmr_device can be either a 32-bit cookie representing a device, or
0045  *  a 32-bit dev_t if the FMH_OF_DEV_T flag is set.  fmr_physical,
0046  *  fmr_offset, and fmr_length are expressed in units of bytes.
0047  *  fmr_owner is either an inode number, or a special value if
0048  *  FMR_OF_SPECIAL_OWNER is set in fmr_flags.
0049  */
0050 struct fsmap {
0051     __u32       fmr_device; /* device id */
0052     __u32       fmr_flags;  /* mapping flags */
0053     __u64       fmr_physical;   /* device offset of segment */
0054     __u64       fmr_owner;  /* owner id */
0055     __u64       fmr_offset; /* file offset of segment */
0056     __u64       fmr_length; /* length of segment */
0057     __u64       fmr_reserved[3];    /* must be zero */
0058 };
0059
0060 struct fsmap_head {
0061     __u32       fmh_iflags; /* control flags */
0062     __u32       fmh_oflags; /* output flags */
0063     __u32       fmh_count;  /* # of entries in array incl. input */
0064     __u32       fmh_entries;    /* # of entries filled in (output). */
0065     __u64       fmh_reserved[6];    /* must be zero */
0066
0067     struct fsmap    fmh_keys[2];    /* low and high keys for the mapping search */
0068     struct fsmap    fmh_recs[]; /* returned records */
0069 };
0070
0071 /* Size of an fsmap_head with room for nr records. */
0072 static inline __kernel_size_t
0073 fsmap_sizeof(
0074     unsigned int    nr)
0075 {
0076     return sizeof(struct fsmap_head) + nr * sizeof(struct fsmap);
0077 }
0078
0079 /* Start the next fsmap query at the end of the current query results. */
0080 static inline void
0081 fsmap_advance(
0082     struct fsmap_head   *head)
0083 {
0084     head->fmh_keys[0] = head->fmh_recs[head->fmh_entries - 1];
0085 }
0086
0087 /*  fmh_iflags values - set by FS_IOC_GETFSMAP caller in the header. */
0088 /* no flags defined yet */
0089 #define FMH_IF_VALID        0
0090
0091 /*  fmh_oflags values - returned in the header segment only. */
0092 #define FMH_OF_DEV_T        0x1 /* fmr_device values will be dev_t */
0093
0094 /*  fmr_flags values - returned for each non-header segment */
0095 #define FMR_OF_PREALLOC     0x1 /* segment = unwritten pre-allocation */
0096 #define FMR_OF_ATTR_FORK    0x2 /* segment = attribute fork */
0097 #define FMR_OF_EXTENT_MAP   0x4 /* segment = extent map */
0098 #define FMR_OF_SHARED       0x8 /* segment = shared with another file */
0099 #define FMR_OF_SPECIAL_OWNER    0x10    /* owner is a special value */
0100 #define FMR_OF_LAST     0x20    /* segment is the last in the dataset */
0101
0102 /* Each FS gets to define its own special owner codes. */
0103 #define FMR_OWNER(type, code)   (((__u64)type << 32) | \
0104                  ((__u64)code & 0xFFFFFFFFULL))
0105 #define FMR_OWNER_TYPE(owner)   ((__u32)((__u64)owner >> 32))
0106 #define FMR_OWNER_CODE(owner)   ((__u32)(((__u64)owner & 0xFFFFFFFFULL)))
0107 #define FMR_OWN_FREE        FMR_OWNER(0, 1) /* free space */
0108 #define FMR_OWN_UNKNOWN     FMR_OWNER(0, 2) /* unknown owner */
0109 #define FMR_OWN_METADATA    FMR_OWNER(0, 3) /* metadata */
0110
0111 #define FS_IOC_GETFSMAP     _IOWR('X', 59, struct fsmap_head)
0112
0113 #endif /* _LINUX_FSMAP_H */