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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.


       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_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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