BDFLUSH(2)						     Linux Programmer's Manual							BDFLUSH(2)

NAME

       bdflush - start, flush, or tune buffer-dirty-flush daemon

SYNOPSIS

       #include <sys/kdaemon.h>

       int bdflush(int func, long *address);
       int bdflush(int func, long data);

DESCRIPTION

       Note:  Since  Linux 2.6, this system call is deprecated and does nothing.  It is likely to disappear altogether in a future kernel release.
       Nowadays, the task performed by bdflush() is handled by the kernel pdflush thread.

       bdflush() starts, flushes, or tunes the buffer-dirty-flush daemon.  Only a privileged process (one with the CAP_SYS_ADMIN  capability)  may
       call bdflush().

       If func is negative or 0, and no daemon has been started, then bdflush() enters the daemon code and never returns.

       If func is 1, some dirty buffers are written to disk.

       If  func  is 2 or more and is even (low bit is 0), then address is the address of a long word, and the tuning parameter numbered (func-2)/2
       is returned to the caller in that address.

       If func is 3 or more and is odd (low bit is 1), then data is a long word, and the kernel sets tuning parameter numbered (func-3)/2 to  that
       value.

       The set of parameters, their values, and their valid ranges are defined in the Linux kernel source file fs/buffer.c.

RETURN VALUE

       If  func  is negative or 0 and the daemon successfully starts, bdflush() never returns.	Otherwise, the return value is 0 on success and -1
       on failure, with errno set to indicate the error.

ERRORS

       EBUSY  An attempt was made to enter the daemon code after another process has already entered.

       EFAULT address points outside your accessible address space.

       EINVAL An attempt was made to read or write an invalid parameter number, or to write an invalid value to a parameter.

       EPERM  Caller does not have the CAP_SYS_ADMIN capability.

VERSIONS

       Since version 2.23, glibc no longer supports this obsolete system call.

CONFORMING TO

       bdflush() is Linux-specific and should not be used in programs intended to be portable.

SEE ALSO

       sync(1), fsync(2), sync(2)

COLOPHON

       This page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and  the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

Linux								    2016-10-08								BDFLUSH(2)