UNIX Filesystems: Evolution, Design, and Implementation

Per Filesystem Statistics

In the same way that the stat() system call can be called to obtain per-file related information, the statvfs() system call can be invoked to obtain per-filesystem information. Note that this information will differ for each different mounted filesystem so that the information obtained for, say, one VxFS filesystem, will not necessarily be the same for other VxFS filesystems.

#include <sys/types.h>
#include <sys/statvfs.h>

int statvfs(const char *path, struct statvfs *buf);
int fstatvfs(int fildes, struct statvfs *buf);

Both functions operate on the statvfs structure, which contains a number of filesystem-specific fields including the following:

u_long      f_bsize;              /* file system block size */
u_long      f_frsize;             /* fundamental filesystem block
                                     (size if supported) */
fsblkcnt_t f_blocks;              /* total # of blocks on file system
                                     in units of f_frsize */
fsblkcnt_t f_bfree;               /* total # of free blocks */
fsblkcnt_t f_bavail;              /* # of free blocks avail to
                                     non-super-user */
fsfilcnt_t f_files;               /* total # of file nodes (inodes) */

fsfilcnt_t f_ffree;               /* total # of free file nodes */
fsfilcnt_t f_favail;              /* # of inodes avail to non-suser*/
u_long      f_fsid;               /* file system id (dev for now) */
char        f_basetype[FSTYPSZ];  /* fs name null-terminated */
u_long      f_flag;               /* bit mask of flags */
u_long      f_namemax;            /* maximum file name length */
char        f_fstr[32];           /* file system specific string */

The statvfs(L) function is not available on Linux. In its place is the statfs(L) function that ...