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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 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.

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

SEE ALSO
       fsync(2), sync(2), sync(8), update(8)

COLOPHON
       This page is part of release 3.22 of the Linux man-pages project.  A description of the project,  and  informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                             2004-06-17                        BDFLUSH(2)