#include <liburing.h> void io_uring_prep_fsync(struct io_uring_sqe *sqe, int fd, unsigned flags);
The io_uring_prep_fsync(3) function prepares an fsync request. The submission queue entry sqe is setup to use the file descriptor fd that should get synced, with the modifier flags indicated by the flags argument.
This function prepares an fsync request. It can act either like an fsync(2) operation, which is the default behavior. If IORING_FSYNC_DATASYNC is set in the flags argument, then it behaves like fdatasync(2). If no range is specified, the fd will be synced from 0 to end-of-file.
It's possible to specify a range to sync, if one is desired. If the off field of the SQE is set to non-zero, then that indicates the offset to start syncing at. If len is set in the SQE, then that indicates the size in bytes to sync from the offset. Note that these fields are not accepted by this helper, so they have to be set manually in the SQE after calling this prep helper.
The CQE res 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 -1 on failure and set errno to the actual error value, io_uring never uses errno. Instead it returns the negated errno directly in the CQE res field.
io_uring_get_sqe(3), io_uring_submit(3), fsync(2), fdatasync(2)