bdflush

NAME

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

SYNOPSIS

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

DESCRIPTION

       bdflush  starts,  flushes, or tunes the buffer-dirty-flush
       daemon.  Only the super-user 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 num-
       bered (func-3)/2 to that value.

       The set of  parameters,  their  values,  and  their  legal
       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

       EPERM   Caller is not super-user.

       EFAULT  address  points  outside  your  accessible address
               space.

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

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

SEE ALSO

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