Add FSCONFIG_CMD_CREATE_EXCL (#1139)

Introduced by Linux 6.6

Author: rusty-snake

src/backend/libc/mount/syscalls.rs

@@ -270,3 +270,17 @@ pub(crate) fn fsconfig_reconfigure(fs_fd: BorrowedFd<'_>) -> io::Result<()> {
         ))
     }
 }
+
+#[cfg(linux_kernel)]
+#[cfg(feature = "mount")]
+pub(crate) fn fsconfig_create_excl(fs_fd: BorrowedFd<'_>) -> io::Result<()> {
+    unsafe {
+        ret(fsconfig(
+            borrowed_fd(fs_fd),
+            super::types::FsConfigCmd::CreateExclusive as _,
+            null(),
+            null(),
+            0,
+        ))
+    }
+}

src/backend/libc/mount/types.rs

@@ -146,6 +146,9 @@ pub(crate) enum FsConfigCmd {
 
     /// `FSCONFIG_CMD_RECONFIGURE`
     Reconfigure = 7,
+
+    /// `FSCONFIG_CMD_CREATE_EXCL`
+    CreateExclusive = 8,
 }
 
 #[cfg(feature = "mount")]

src/backend/linux_raw/mount/syscalls.rs

@@ -237,3 +237,18 @@ pub(crate) fn fsconfig_reconfigure(fs_fd: BorrowedFd<'_>) -> io::Result<()> {
         ))
     }
 }
+
+#[cfg(feature = "mount")]
+#[inline]
+pub(crate) fn fsconfig_create_excl(fs_fd: BorrowedFd<'_>) -> io::Result<()> {
+    unsafe {
+        ret(syscall_readonly!(
+            __NR_fsconfig,
+            fs_fd,
+            super::types::FsConfigCmd::CreateExclusive,
+            zero(),
+            zero(),
+            zero()
+        ))
+    }
+}

src/backend/linux_raw/mount/types.rs

@@ -144,6 +144,9 @@ pub(crate) enum FsConfigCmd {
 
     /// `FSCONFIG_CMD_RECONFIGURE`
     Reconfigure = linux_raw_sys::general::fsconfig_command::FSCONFIG_CMD_RECONFIGURE as u32,
+
+    /// `FSCONFIG_CMD_CREATE_EXCL`
+    CreateExclusive = linux_raw_sys::general::fsconfig_command::FSCONFIG_CMD_CREATE_EXCL as u32,
 }
 
 #[cfg(feature = "mount")]

src/mount/fsopen.rs

@@ -217,3 +217,15 @@ pub fn fsconfig_create(fs_fd: BorrowedFd<'_>) -> io::Result<()> {
 pub fn fsconfig_reconfigure(fs_fd: BorrowedFd<'_>) -> io::Result<()> {
     backend::mount::syscalls::fsconfig_reconfigure(fs_fd)
 }
+
+/// `fsconfig(fs_fd, FSCONFIG_CMD_CREATE_EXCL, key, NULL, 0)`
+///
+/// # References
+///  - [Unfinished draft]
+///
+/// [Unfinished draft]: https://github.com/sunfishcode/linux-mount-api-documentation/blob/main/fsconfig.md
+#[inline]
+#[doc(alias = "fsconfig")]
+pub fn fsconfig_create_exclusive(fs_fd: BorrowedFd<'_>) -> io::Result<()> {
+    backend::mount::syscalls::fsconfig_create_excl(fs_fd)
+}