man3/statvfs.3

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  25 .\" The pathconf note is from Walter Harms
  26 .\" This is not a system call on Linux
  27 .\"
  28 .\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
  29 .\"
  30 .TH STATVFS 3 2017-09-15 "Linux" "Linux Programmer's Manual"
  31 .SH NAME
  32 statvfs, fstatvfs \- get filesystem statistics
  33 .SH SYNOPSIS
  34 .B #include <sys/statvfs.h>
  35 .PP
  36 .BI "int statvfs(const char *" path ", struct statvfs *" buf );
  37 .br
  38 .BI "int fstatvfs(int " fd ", struct statvfs *" buf );
  39 .SH DESCRIPTION
  40 The function
  41 .BR statvfs ()
  42 returns information about a mounted filesystem.
  43 .I path
  44 is the pathname of any file within the mounted filesystem.
  45 .I buf
  46 is a pointer to a
  47 .I statvfs
  48 structure defined approximately as follows:
  49 .PP
  50 .in +4n
  51 .EX
  52 struct statvfs {
  53     unsigned long  f_bsize;    /* Filesystem block size */
  54     unsigned long  f_frsize;   /* Fragment size */
  55     fsblkcnt_t     f_blocks;   /* Size of fs in f_frsize units */
  56     fsblkcnt_t     f_bfree;    /* Number of free blocks */
  57     fsblkcnt_t     f_bavail;   /* Number of free blocks for
  58                                   unprivileged users */
  59     fsfilcnt_t     f_files;    /* Number of inodes */
  60     fsfilcnt_t     f_ffree;    /* Number of free inodes */
  61     fsfilcnt_t     f_favail;   /* Number of free inodes for
  62                                   unprivileged users */
  63     unsigned long  f_fsid;     /* Filesystem ID */
  64     unsigned long  f_flag;     /* Mount flags */
  65     unsigned long  f_namemax;  /* Maximum filename length */
  66 };
  67 .EE
  68 .in
  69 .PP
  70 Here the types
  71 .I fsblkcnt_t
  72 and
  73 .I fsfilcnt_t
  74 are defined in
  75 .IR <sys/types.h> .
  76 Both used to be
  77 .IR "unsigned long" .
  78 .PP
  79 The field
  80 .I f_flag
  81 is a bit mask indicating various options that were employed
  82 when mounting this filesystem.
  83 It contains zero or more of the following flags:
  84 .\" XXX Keep this list in sync with statfs(2)
  85 .TP
  86 .B ST_MANDLOCK
  87 Mandatory locking is permitted on the filesystem (see
  88 .BR fcntl (2)).
  89 .TP
  90 .B ST_NOATIME
  91 Do not update access times; see
  92 .BR mount (2).
  93 .TP
  94 .B ST_NODEV
  95 Disallow access to device special files on this filesystem.
  96 .TP
  97 .B ST_NODIRATIME
  98 Do not update directory access times; see
  99 .BR mount (2).
 100 .TP
 101 .B ST_NOEXEC
 102 Execution of programs is disallowed on this filesystem.
 103 .TP
 104 .B ST_NOSUID
 105 The set-user-ID and set-group-ID bits are ignored by
 106 .BR exec (3)
 107 for executable files on this filesystem
 108 .TP
 109 .B ST_RDONLY
 110 This filesystem is mounted read-only.
 111 .TP
 112 .B ST_RELATIME
 113 Update atime relative to mtime/ctime; see
 114 .BR mount (2).
 115 .TP
 116 .B ST_SYNCHRONOUS
 117 Writes are synched to the filesystem immediately (see the description of
 118 .B O_SYNC
 119 in
 120 .BR open (2)).
 121 .PP
 122 It is unspecified whether all members of the returned struct
 123 have meaningful values on all filesystems.
 124 .PP
 125 .BR fstatvfs ()
 126 returns the same information about an open file referenced by descriptor
 127 .IR fd .
 128 .SH RETURN VALUE
 129 On success, zero is returned.
 130 On error, \-1 is returned, and
 131 .I errno
 132 is set appropriately.
 133 .SH ERRORS
 134 .TP
 135 .B EACCES
 136 .RB ( statvfs ())
 137 Search permission is denied for a component of the path prefix of
 138 .IR path .
 139 (See also
 140 .BR path_resolution (7).)
 141 .TP
 142 .B EBADF
 143 .RB ( fstatvfs ())
 144 .I fd
 145 is not a valid open file descriptor.
 146 .TP
 147 .B EFAULT
 148 .I Buf
 149 or
 150 .I path
 151 points to an invalid address.
 152 .TP
 153 .B EINTR
 154 This call was interrupted by a signal; see
 155 .BR signal (7).
 156 .TP
 157 .B EIO
 158 An I/O error occurred while reading from the filesystem.
 159 .TP
 160 .B ELOOP
 161 .RB ( statvfs ())
 162 Too many symbolic links were encountered in translating
 163 .IR path .
 164 .TP
 165 .B ENAMETOOLONG
 166 .RB ( statvfs ())
 167 .I path
 168 is too long.
 169 .TP
 170 .B ENOENT
 171 .RB ( statvfs ())
 172 The file referred to by
 173 .I path
 174 does not exist.
 175 .TP
 176 .B ENOMEM
 177 Insufficient kernel memory was available.
 178 .TP
 179 .B ENOSYS
 180 The filesystem does not support this call.
 181 .TP
 182 .B ENOTDIR
 183 .RB ( statvfs ())
 184 A component of the path prefix of
 185 .I path
 186 is not a directory.
 187 .TP
 188 .B EOVERFLOW
 189 Some values were too large to be represented in the returned struct.
 190 .SH ATTRIBUTES
 191 For an explanation of the terms used in this section, see
 192 .BR attributes (7).
 193 .TS
 194 allbox;
 195 lbw21 lb lb
 196 l l l.
 197 Interface       Attribute       Value
 198 T{
 199 .BR statvfs (),
 200 .BR fstatvfs ()
 201 T}      Thread safety   MT-Safe
 202 .TE
 203 .SH CONFORMING TO
 204 POSIX.1-2001, POSIX.1-2008.
 205 .PP
 206 Only the
 207 .B ST_NOSUID
 208 and
 209 .B ST_RDONLY
 210 flags of the
 211 .I f_flag
 212 field are specified in POSIX.1.
 213 To obtain definitions of the remaining flags, one must define
 214 .BR _GNU_SOURCE .
 215 .SH NOTES
 216 The Linux kernel has system calls
 217 .BR statfs (2)
 218 and
 219 .BR fstatfs (2)
 220 to support this library call.
 221 .PP
 222 In glibc versions before 2.13,
 223 .\" glibc commit 3cdaa6adb113a088fdfb87aa6d7747557eccc58d
 224 .BR statvfs ()
 225 populated the bits of the
 226 .IR f_flag
 227 field by scanning the mount options shown in
 228 .IR /proc/mounts .
 229 However, starting with Linux 2.6.36, the underlying
 230 .BR statfs (2)
 231 system call provides the necessary information via the
 232 .IR f_flags
 233 field, and since glibc version 2.13, the
 234 .BR statvfs ()
 235 function will use information from that field rather than scanning
 236 .IR /proc/mounts .
 237 .PP
 238 The glibc implementations of
 239 .PP
 240 .in +4n
 241 .EX
 242 pathconf(path, _PC_REC_XFER_ALIGN);
 243 pathconf(path, _PC_ALLOC_SIZE_MIN);
 244 pathconf(path, _PC_REC_MIN_XFER_SIZE);
 245 .EE
 246 .in
 247 .PP
 248 respectively use the
 249 .IR f_frsize ,
 250 .IR f_frsize ,
 251 and
 252 .I f_bsize
 253 fields returned by a call to
 254 .BR statvfs ()
 255 with the argument
 256 .IR path .
 257 .SH SEE ALSO
 258 .BR statfs (2)