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| 1 | .TH io_cancel 2 2002-09-03 "Linux 2.4" "Linux AIO" |
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| 2 | .SH NAME |
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| 3 | io_cancel \- Cancel io requests |
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| 4 | .SH SYNOPSIS |
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| 5 | .nf |
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| 6 | .B #include <errno.h> |
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| 7 | .sp |
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| 8 | .br |
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| 9 | .B #include <libaio.h> |
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| 10 | .sp |
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| 11 | .br |
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| 12 | .BI "int io_cancel(io_context_t ctx, struct iocb *iocb)" |
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| 13 | .br |
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| 14 | .sp |
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| 15 | struct iocb { |
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| 16 | void *data; /* Return in the io completion event */ |
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| 17 | unsigned key; /* For use in identifying io requests */ |
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| 18 | short aio_lio_opcode; |
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| 19 | short aio_reqprio; /* Not used */ |
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| 20 | int aio_fildes; |
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| 21 | }; |
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| 22 | .fi |
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| 23 | .SH DESCRIPTION |
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| 24 | Attempts to cancel an iocb previously passed to io_submit. If |
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| 25 | the operation is successfully cancelled, the resulting event is |
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| 26 | copied into the memory pointed to by result without being placed |
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| 27 | into the completion queue. |
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| 28 | .PP |
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| 29 | When one or more requests are asynchronously processed, it might be |
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| 30 | useful in some situations to cancel a selected operation, e.g., if it |
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| 31 | becomes obvious that the written data is no longer accurate and would |
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| 32 | have to be overwritten soon. As an example, assume an application, which |
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| 33 | writes data in files in a situation where new incoming data would have |
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| 34 | to be written in a file which will be updated by an enqueued request. |
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| 35 | .SH "RETURN VALUES" |
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| 36 | 0 is returned on success , otherwise returns Errno. |
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| 37 | .SH ERRORS |
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| 38 | .TP |
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| 39 | .B EFAULT |
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| 40 | If any of the data structures pointed to are invalid. |
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| 41 | .TP |
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| 42 | .B EINVAL |
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| 43 | If aio_context specified by ctx_id is |
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| 44 | invalid. |
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| 45 | .TP |
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| 46 | .B EAGAIN |
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| 47 | If the iocb specified was not |
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| 48 | cancelled. |
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| 49 | .TP |
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| 50 | .B ENOSYS |
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| 51 | if not implemented. |
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| 52 | .SH "SEE ALSO" |
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| 53 | .BR io(3), |
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| 54 | .BR io_fsync(3), |
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| 55 | .BR io_getevents(3), |
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| 56 | .BR io_prep_fsync(3), |
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| 57 | .BR io_prep_pread(3), |
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| 58 | .BR io_prep_pwrite(3), |
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| 59 | .BR io_queue_init(3), |
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| 60 | .BR io_queue_release(3), |
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| 61 | .BR io_queue_run(3), |
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| 62 | .BR io_queue_wait(3), |
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| 63 | .BR io_set_callback(3), |
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| 64 | .BR io_submit(3), |
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| 65 | .BR errno(3) |
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