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  5.10  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)