BDFLUSH
Section: Linux Programmer's Manual (2)
Updated: 2021-03-22
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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);
Note:
There is no glibc wrapper for this system call; see VERSIONS.
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.
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)
COLOPHON
This page is part of release 5.11 of the Linux
man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
https://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- VERSIONS
-
- CONFORMING TO
-
- SEE ALSO
-
- COLOPHON
-
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Time: 06:22:43 GMT, May 09, 2021