Fixes needed by io_uring.

 - Have the `io_uring` module export more types used in opcode entries.
 - Define a conversion from `SocketAddr` to `SocketAddrAny`.
 - Add comments to the `fadvise` implementation.

src/backend/linux_raw/fs/syscalls.rs

@@ -378,6 +378,7 @@ pub(crate) fn fadvise(fd: BorrowedFd<'_>, pos: u64, len: u64, advice: Advice) ->
             lo(len)
         ))
     }
+
     // On mips, the arguments are not reordered, and padding is inserted
     // instead to ensure alignment.
     #[cfg(any(target_arch = "mips", target_arch = "mips32r6"))]
@@ -393,6 +394,9 @@ pub(crate) fn fadvise(fd: BorrowedFd<'_>, pos: u64, len: u64, advice: Advice) ->
             advice
         ))
     }
+
+    // For all other 32-bit architectures, use `fadvise64_64` so that we get a
+    // 64-bit length.
     #[cfg(all(
         target_pointer_width = "32",
         not(any(
@@ -413,6 +417,8 @@ pub(crate) fn fadvise(fd: BorrowedFd<'_>, pos: u64, len: u64, advice: Advice) ->
             advice
         ))
     }
+
+    // On 64-bit architectures, use `fadvise64` which is sufficient.
     #[cfg(target_pointer_width = "64")]
     unsafe {
         ret(syscall_readonly!(

src/io_uring.rs

@@ -35,6 +35,40 @@ use linux_raw_sys::net;
 pub use crate::fs::{Advice, AtFlags, OFlags, RenameFlags, ResolveFlags, Statx};
 pub use crate::net::{RecvFlags, SendFlags, SocketFlags};
 pub use crate::timespec::Timespec;
+pub use linux_raw_sys::general::sigset_t;
+
+pub use net::{__kernel_sockaddr_storage as sockaddr_storage, msghdr, sockaddr, socklen_t};
+
+// Declare the `c_char` type for use with entries that take pointers
+// to C strings. Define it as unsigned or signed according to the platform
+// so that we match what Rust's `CStr` uses.
+//
+// When we can update to linux-raw-sys 0.5, we can remove this, as its
+// `c_char` type will declare this.
+/// The C `char` type.
+#[cfg(any(
+    target_arch = "aarch64",
+    target_arch = "arm",
+    target_arch = "msp430",
+    target_arch = "powerpc",
+    target_arch = "powerpc64",
+    target_arch = "riscv32",
+    target_arch = "riscv64",
+    target_arch = "s390x",
+))]
+#[allow(non_camel_case_types)]
+pub type c_char = u8;
+/// The C `char` type.
+#[cfg(any(
+    target_arch = "mips",
+    target_arch = "mips64",
+    target_arch = "sparc64",
+    target_arch = "x86",
+    target_arch = "x86_64",
+    target_arch = "xtensa",
+))]
+#[allow(non_camel_case_types)]
+pub type c_char = i8;
 
 mod sys {
     pub(super) use linux_raw_sys::io_uring::*;
@@ -1393,6 +1427,8 @@ impl Default for register_or_sqe_op_or_sqe_flags_union {
 fn io_uring_layouts() {
     use sys as c;
 
+    check_renamed_type!(io_uring_ptr, u64);
+
     check_renamed_type!(off_or_addr2_union, io_uring_sqe__bindgen_ty_1);
     check_renamed_type!(addr_or_splice_off_in_union, io_uring_sqe__bindgen_ty_2);
     check_renamed_type!(addr3_or_cmd_union, io_uring_sqe__bindgen_ty_6);

src/net/socket_addr_any.rs

@@ -11,7 +11,7 @@
 
 #[cfg(unix)]
 use crate::net::SocketAddrUnix;
-use crate::net::{AddressFamily, SocketAddrV4, SocketAddrV6};
+use crate::net::{AddressFamily, SocketAddr, SocketAddrV4, SocketAddrV6};
 use crate::{backend, io};
 #[cfg(feature = "std")]
 use core::fmt;
@@ -32,6 +32,16 @@ pub enum SocketAddrAny {
     Unix(SocketAddrUnix),
 }
 
+impl From<SocketAddr> for SocketAddrAny {
+    #[inline]
+    fn from(from: SocketAddr) -> Self {
+        match from {
+            SocketAddr::V4(v4) => Self::V4(v4),
+            SocketAddr::V6(v6) => Self::V6(v6),
+        }
+    }
+}
+
 impl From<SocketAddrV4> for SocketAddrAny {
     #[inline]
     fn from(from: SocketAddrV4) -> Self {