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       io_submit - submit asynchronous I/O blocks for processing


       #include <linux/aio_abi.h>          /* Defines needed types */

       int io_submit(aio_context_t ctx_id, long nr, struct iocb **iocbpp);

       Note: There is no glibc wrapper for this system call; see NOTES.


       Note:  this  page  describes  the  raw  Linux system call interface.  The wrapper function
       provided by libaio uses a different type for the ctx_id argument.  See NOTES.

       The io_submit() system call queues nr I/O request blocks for processing in the AIO context
       ctx_id.   The  iocbpp  argument should be an array of nr AIO control blocks, which will be
       submitted to context ctx_id.

       The iocb (I/O control block) structure defined in linux/aio_abi.h defines  the  parameters
       that control the I/O operation.

           #include <linux/aio_abi.h>

           struct iocb {
               __u64   aio_data;
               __u32   PADDED(aio_key, aio_rw_flags);
               __u16   aio_lio_opcode;
               __s16   aio_reqprio;
               __u32   aio_fildes;
               __u64   aio_buf;
               __u64   aio_nbytes;
               __s64   aio_offset;
               __u64   aio_reserved2;
               __u32   aio_flags;
               __u32   aio_resfd;

       The fields of this structure are as follows:

              This  data  is  copied  into  the  data  field  of  the io_event structure upon I/O
              completion (see io_getevents(2)).

              This is an internal field used by the kernel.  Do not modify this  field  after  an
              io_submit() call.

              This defines the R/W flags passed with structure.  The valid values are:

              RWF_APPEND (since Linux 4.16)
                     Append  data to the end of the file.  See the description of the flag of the
                     same name in pwritev2(2) as well as the description of O_APPEND in  open(2).
                     The aio_offset field is ignored.  The file offset is not changed.

              RWF_DSYNC (since Linux 4.13)
                     Write  operation  complete according to requirement of synchronized I/O data
                     integrity.  See the description of the flag of the same name in  pwritev2(2)
                     as well the description of O_DSYNC in open(2).

              RWF_HIPRI (since Linux 4.13)
                     High priority request, poll if possible

              RWF_NOWAIT (since Linux 4.14)
                     Don't  wait  if  the  I/O  will  block  for  operations  such  as file block
                     allocations, dirty page flush, mutex locks,  or  a  congested  block  device
                     inside the kernel.  If any of these conditions are met, the control block is
                     returned immediately with a return value of -EAGAIN in the res field of  the
                     io_event structure (see io_getevents(2)).

              RWF_SYNC (since Linux 4.13)
                     Write  operation  complete according to requirement of synchronized I/O file
                     integrity.  See the description of the flag of the same name in  pwritev2(2)
                     as well the description of O_SYNC in open(2).

              This  defines  the  type  of  I/O to be performed by the iocb structure.  The valid
              values are defined by the enum defined in linux/aio_abi.h:

                  enum {
                      IOCB_CMD_PREAD = 0,
                      IOCB_CMD_PWRITE = 1,
                      IOCB_CMD_FSYNC = 2,
                      IOCB_CMD_FDSYNC = 3,
                      IOCB_CMD_POLL = 5,
                      IOCB_CMD_NOOP = 6,
                      IOCB_CMD_PREADV = 7,
                      IOCB_CMD_PWRITEV = 8,

              This defines the requests priority.

              The file descriptor on which the I/O operation is to be performed.

              This is the buffer used to transfer data for a read or write operation.

              This is the size of the buffer pointed to by aio_buf.

              This is the file offset at which the I/O operation is to be performed.

              This is the set of flags associated with the iocb structure.  The valid values are:

                     Asynchronous I/O control  must  signal  the  file  descriptor  mentioned  in
                     aio_resfd upon completion.

              IOCB_FLAG_IOPRIO (since Linux 4.18)
                     Interpret   the   aio_reqprio   field  as  an  IOPRIO_VALUE  as  defined  by

              The file descriptor to signal in the event of asynchronous I/O completion.


       On success, io_submit() returns the number of iocbs submitted (which may be less than  nr,
       or 0 if nr is zero).  For the failure return, see NOTES.


       EAGAIN Insufficient resources are available to queue any iocbs.

       EBADF  The file descriptor specified in the first iocb is invalid.

       EFAULT One of the data structures points to invalid data.

       EINVAL The  AIO  context  specified by ctx_id is invalid.  nr is less than 0.  The iocb at
              *iocbpp[0] is not properly initialized, the operation specified is invalid for  the
              file descriptor in the iocb, or the value in the aio_reqprio field is invalid.

       ENOSYS io_submit() is not implemented on this architecture.

       EPERM  The  aio_reqprio  field  is  set with the class IOPRIO_CLASS_RT, but the submitting
              context does not have the CAP_SYS_ADMIN capability.


       The asynchronous I/O system calls first appeared in Linux 2.5.


       io_submit() is Linux-specific and should not be used in programs that are intended  to  be


       Glibc does not provide a wrapper function for this system call.  You could invoke it using
       syscall(2).  But instead, you probably  want  to  use  the  io_submit()  wrapper  function
       provided by libaio.

       Note  that the libaio wrapper function uses a different type (io_context_t) for the ctx_id
       argument.  Note also that  the  libaio  wrapper  does  not  follow  the  usual  C  library
       conventions  for  indicating  errors:  on  error  it  returns  a negated error number (the
       negative of one of the values listed in ERRORS).   If  the  system  call  is  invoked  via
       syscall(2),  then  the return value follows the usual conventions for indicating an error:
       -1, with errno set to a (positive) value that indicates the error.


       io_cancel(2), io_destroy(2), io_getevents(2), io_setup(2), aio(7)


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