bdflush(2)

1bdflush(2)                    System Calls Manual                   bdflush(2)
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NAME

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

9       #include <sys/kdaemon.h>
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11       [[deprecated]] int bdflush(int func, long *address);
12       [[deprecated]] int bdflush(int func, long data);
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DESCRIPTION

15       Note: Since Linux 2.6, this system call is deprecated and does nothing.
16       It is likely to disappear altogether in a future kernel release.  Nowa‐
17       days,  the task performed by bdflush() is handled by the kernel pdflush
18       thread.
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20       bdflush() starts, flushes,  or  tunes  the  buffer-dirty-flush  daemon.
21       Only  a  privileged process (one with the CAP_SYS_ADMIN capability) may
22       call bdflush().
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24       If func is negative or 0, and no daemon  has  been  started,  then  bd‐
25       flush() enters the daemon code and never returns.
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27       If func is 1, some dirty buffers are written to disk.
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29       If  func  is  2 or more and is even (low bit is 0), then address is the
30       address of a long word, and the tuning parameter numbered (func-2)/2 is
31       returned to the caller in that address.
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33       If  func  is  3  or more and is odd (low bit is 1), then data is a long
34       word, and the kernel sets tuning parameter numbered (func-3)/2 to  that
35       value.
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37       The set of parameters, their values, and their valid ranges are defined
38       in the Linux kernel source file fs/buffer.c.
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RETURN VALUE

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

46       EBUSY  An attempt was made to  enter  the  daemon  code  after  another
47              process has already entered.
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49       EFAULT address points outside your accessible address space.
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51       EINVAL An  attempt  was made to read or write an invalid parameter num‐
52              ber, or to write an invalid value to a parameter.
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54       EPERM  Caller does not have the CAP_SYS_ADMIN capability.
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STANDARDS

57       Linux.
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HISTORY

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