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.

CONFORMING TO

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

SEE ALSO

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

COLOPHON

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