drivers: fs: tmpfs: new

Add tmpfs driver and register with the kernel driver's FS subsystem.

src/drivers/fs/mod.rs

@@ -1,15 +1,18 @@
 use alloc::sync::Arc;
 use dev::DevFsDriver;
 use fat32::Fat32FsDriver;
+use tmpfs::TmpFsDriver;
 
 use super::DM;
 
 pub mod dev;
 pub mod fat32;
+pub mod tmpfs;
 
 pub fn register_fs_drivers() {
     let mut dm = DM.lock_save_irq();
 
     dm.insert_driver(Arc::new(Fat32FsDriver::new()));
     dm.insert_driver(Arc::new(DevFsDriver::new()));
+    dm.insert_driver(Arc::new(TmpFsDriver::new()));
 }

src/drivers/fs/tmpfs.rs

@@ -0,0 +1,47 @@
+use crate::{arch::ArchImpl, drivers::Driver, fs::FilesystemDriver, memory::{PageOffsetTranslator, page::PgAllocGetter}};
+use alloc::{boxed::Box, sync::Arc};
+use async_trait::async_trait;
+use libkernel::{
+    error::{KernelError, Result},
+    fs::{BlockDevice, Filesystem},
+};
+use log::warn;
+
+pub struct TmpFsDriver {}
+
+impl TmpFsDriver {
+    pub fn new() -> Self {
+        Self {}
+    }
+}
+
+impl Driver for TmpFsDriver {
+    fn name(&self) -> &'static str {
+        "tmpfs"
+    }
+
+    fn as_filesystem_driver(self: Arc<Self>) -> Option<Arc<dyn FilesystemDriver>> {
+        Some(self)
+    }
+}
+
+#[async_trait]
+impl FilesystemDriver for TmpFsDriver {
+    async fn construct(
+        &self,
+        fs_id: u64,
+        device: Option<Box<dyn BlockDevice>>,
+    ) -> Result<Arc<dyn Filesystem>> {
+        match device {
+            Some(_) => {
+                warn!("Unexpected block device for tmpfs");
+                Err(KernelError::InvalidValue)
+            }
+            None => Ok(libkernel::fs::filesystems::tmpfs::TmpFs::<
+                ArchImpl,
+                PgAllocGetter,
+                PageOffsetTranslator,
+            >::new(fs_id)),
+        }
+    }
+}