Manpage of BDFLUSH

BDFLUSH

Section: Linux Programmer's Manual (2)
Updated: 2016-10-08
Index
 

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 pdflushthread.

bdflush() starts, flushes, or tunes the buffer-dirty-flush daemon. Only a privileged process (one with the CAP_SYS_ADMINcapability) may call bdflush().

If funcis negative or 0, and no daemon has been started, then bdflush() enters the daemon code and never returns.

If funcis 1, some dirty buffers are written to disk.

If funcis 2 or more and is even (low bit is 0), then addressis the address of a long word, and the tuning parameter numbered (func-2)/2 is returned to the caller in that address.

If funcis 3 or more and is odd (low bit is 1), then datais 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 funcis negative or 0 and the daemon successfully starts, bdflush() never returns. Otherwise, the return value is 0 on success and -1 on failure, with errnoset to indicate the error.  

ERRORS

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

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)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
VERSIONS
CONFORMING TO
SEE ALSO

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