SYNCFS(3C) Standard C Library Functions SYNCFS(3C)

NAME

syncfs - synchronize file system to disk

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <unistd.h>

int
syncfs(int fd);

DESCRIPTION

The syncfs() function instructs the file system associated with the file
descriptor, fd, to ensure that all pending data and metadata updates that
are still in-memory are synchronized back to the file system's underlying
storage devices. This function will block until all such writes are
completed.

Not all file systems support this request. This may happen either because
the file system has not been enhanced yet to support this request or
because the file system does not support the idea of synchronizing data to
a backing store such as the underlying socket file system or the read-only
bootfs(4FS) file system.

If an application only cares about the state of a single file and its
metadata, then it should use the fsync(3C) function instead. The
traditional sync(2) function has two primary differences from the syncfs()
function: sync(2) instructs the system to schedule all I/O across all file
systems to be synchronized and it does not guarantee that all that I/O is
completed prior to returning. There is no non-blocking way to force I/O to
be synchronized to a specific file system.

RETURN VALUES

Upon successful completion, the syncfs() function returns 0 and ensures
that the file system data and metadata synchronization has already
completed. Otherwise -1 is returned and errno is set to indicate the error
and outstanding file system data and metadata is not guaranteed to have
been synchronized.

ERRORS

The syncfs() functions will fail if:

EBADF The fd argument is not a valid open file descriptor in
the calling process.

EDQUOT, ENOSPC There was no free space remaining on the file system's
backing store or a quota was hit.

EIO An I/O error occurred while reading or writing.

ENOSYS The file system backing the file descriptor, fd, does
not support file system-wide synchronization.

It is possible that a remote file system (e.g. NFS) may fail with
additional errors that are unique to the network based nature of the file
system.

INTERFACE STABILITY

Committed

MT-LEVEL
Safe

SEE ALSO

sync(2), fsync(3C)

illumos July 13, 2024 illumos