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NAME |SYNOPSIS |DESCRIPTION |RETURN VALUE |ERRORS |NOTES |SEE ALSO |COLOPHON | |
io_uring_prep_readv2(3) liburing Manualio_uring_prep_readv2(3)io_uring_prep_readv2 - prepare vector I/O read request with flags
#include <sys/uio.h>#include <liburing.h>void io_uring_prep_readv2(struct io_uring_sqe *sqe,intfd,const struct iovec *iovecs,unsignednr_vecs,__u64offset,intflags);
Theio_uring_prep_readv2(3) prepares a vectored IO read request. The submission queue entrysqe is setup to use the file descriptorfd to start readingnr_vecs into theiovecs array at the specifiedoffset. The behavior of the function can be controlled with theflags parameter. Supported values forflags are:RWF_HIPRI High priority request, poll if possibleRWF_DSYNC per-IO O_DSYNCRWF_SYNC per-IO O_SYNCRWF_NOWAIT per-IO, return-EAGAINif operation would blockRWF_APPEND per-IO O_APPEND On files that support seeking, if the offset is set to-1, the read operation commences at the file offset, and the file offset is incremented by the number of bytes read. Seeread(2) for more details. Note that for an async API, reading and updating the current file offset may result in unpredictable behavior, unless access to the file is serialized. It is not encouraged to use this feature, if it's possible to provide the desired IO offset from the application or library. On files that are not capable of seeking, the offset must be 0 or -1. After the read has been prepared, it can be submitted with one of the submit functions.
None
The CQEres field will contain the result of the operation. See the related man page for details on possible values. Note that where synchronous system calls will return-1on failure and seterrno to the actual error value, io_uring never useserrno. Instead it returns the negatederrno directly in the CQEres field.
Unless an application explicitly needs to pass in more than one iovec, it is more efficient to useio_uring_prep_read(3) rather than this function, as no state has to be maintained for a non- vectored IO request. As with any request that passes in data in a struct, that data must remain valid until the request has been successfully submitted. It need not remain valid until completion. Once a request has been submitted, the in-kernel state is stable. Very early kernels (5.4 and earlier) required state to be stable until the completion occurred. Applications can test for this behavior by inspecting theIORING_FEAT_SUBMIT_STABLEflag passed back fromio_uring_queue_init_params(3).
io_uring_get_sqe(3),io_uring_prep_read(3),io_uring_prep_readv(3),io_uring_submit(3)
This page is part of theliburing (A library for io_uring) project. Information about the project can be found at ⟨https://github.com/axboe/liburing⟩. If you have a bug report for this manual page, send it to io-uring@vger.kernel.org. This page was obtained from the project's upstream Git repository ⟨https://github.com/axboe/liburing⟩ on 2025-08-11. (At that time, the date of the most recent commit that was found in the repository was 2025-08-02.) If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up-to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which isnot part of the original manual page), send a mail to man-pages@man7.orgliburing-2.1 November 15, 2021io_uring_prep_readv2(3)Pages that refer to this page:io_uring_prep_read(3), io_uring_prep_readv2(3), io_uring_prep_readv(3)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |