NAME

       PR_SET_IO_FLUSHER - change the IO_FLUSHER state

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <linux/prctl.h>  /* Definition of PR_* constants */
       #include <sys/prctl.h>

       int prctl(PR_SET_IO_FLUSHER, long state, 0L, 0L, 0L);

DESCRIPTION

       If  a user process is involved in the block layer or filesystem I/O path, and can allocate
       memory while processing I/O requests it must set state to 1.  This will put the process in
       the  IO_FLUSHER  state, which allows it special treatment to make progress when allocating
       memory.  If state is 0, the process will clear  the  IO_FLUSHER  state,  and  the  default
       behavior will be used.

       The calling process must have the CAP_SYS_RESOURCE capability.

       The  IO_FLUSHER state is inherited by a child process created via fork(2) and is preserved
       across execve(2).

       Examples of IO_FLUSHER applications are FUSE daemons, SCSI device emulation  daemons,  and
       daemons that perform error handling like multipath path recovery applications.

RETURN VALUE

       On  success,  0  is  returned.  On error, -1 is returned, and errno is set to indicate the
       error.

ERRORS

       EINVAL state is not a valid value.

STANDARDS

       Linux.

HISTORY

       Linux 5.6.

SEE ALSO

       prctl(2), PR_GET_IO_FLUSHER(2const)