Demote LockedFileDescription to solve borrow rules

src/context/context.rs

@@ -16,12 +16,12 @@ use crate::{
     },
     cpu_set::{LogicalCpuId, LogicalCpuSet},
     cpu_stats,
-    ipi::{ipi, IpiKind, IpiTarget},
-    memory::{allocate_p2frame, deallocate_p2frame, Enomem, Frame, RaiiFrame},
+    ipi::{IpiKind, IpiTarget, ipi},
+    memory::{Enomem, Frame, RaiiFrame, allocate_p2frame, deallocate_p2frame},
     paging::{RmmA, RmmArch},
     percpu::PercpuBlock,
     scheme::{CallerCtx, FileHandle, SchemeId},
-    sync::{CleanLockToken, RwLock, L1},
+    sync::{CleanLockToken, L1, L4, LockToken, RwLock},
     syscall::usercopy::UserSliceRw,
 };
 
@@ -824,7 +824,7 @@ impl FdTbl {
         &self,
         scheme_id: SchemeId,
         scheme_number: usize,
-        token: &mut CleanLockToken,
+        token: &mut LockToken<L4>,
     ) -> Result<FileDescriptor> {
         self.iter()
             .flatten()

src/context/file.rs

@@ -3,13 +3,13 @@
 use crate::{
     event,
     scheme::{self, SchemeId},
-    sync::{CleanLockToken, RwLock, L1},
+    sync::{CleanLockToken, RwLock, L5},
     syscall::error::Result,
 };
 use alloc::sync::Arc;
 use syscall::{schemev2::NewFdFlags, RwFlags, O_APPEND, O_NONBLOCK};
 
-pub type LockedFileDescription = RwLock<L1, FileDescription>;
+pub type LockedFileDescription = RwLock<L5, FileDescription>;
 
 /// A file description
 #[derive(Clone, Copy, Debug)]

src/scheme/user.rs

@@ -1010,11 +1010,13 @@ impl UserInner {
 
         let (pid, desc) = {
             let context_lock = context::current();
-            let context = context_lock.read(token.token());
-            let desc = context
-                .files
-                .read()
-                .find_by_scheme(self.scheme_id, file, token)?;
+            let mut context = context_lock.read(token.token());
+            let (context, mut lock_token) = context.token_split();
+            let desc =
+                context
+                    .files
+                    .read()
+                    .find_by_scheme(self.scheme_id, file, &mut lock_token)?;
             (context.pid, desc.description)
         };
 

src/syscall/fs.rs

@@ -333,9 +333,10 @@ fn fdwrite_inner(
     let (scheme, number, descs_to_send) = {
         let (scheme, number) = {
             let current_lock = context::current();
-            let current = current_lock.read(token.token());
+            let mut current = current_lock.read(token.token());
+            let (current, mut lock_token) = current.token_split();
             let file_descriptor = current.get_file(socket).ok_or(Error::new(EBADF))?;
-            let desc = &file_descriptor.description.read(token.token());
+            let desc = &file_descriptor.description.read(lock_token.token());
             (desc.scheme, desc.number)
         };
         let scheme = scheme::get_scheme(token.token(), scheme)?;
@@ -384,9 +385,10 @@ fn call_fdread(
     let (scheme, number) = {
         let (scheme, number) = {
             let current_lock = context::current();
-            let current = current_lock.read(token.token());
+            let mut current = current_lock.read(token.token());
+            let (current, mut lock_token) = current.token_split();
             let file_descriptor = current.get_file(fd).ok_or(Error::new(EBADF))?;
-            let desc = file_descriptor.description.read(token.token());
+            let desc = file_descriptor.description.read(lock_token.token());
             (desc.scheme, desc.number)
         };
         let scheme = scheme::get_scheme(token.token(), scheme)?;
@@ -422,7 +424,10 @@ pub fn fcntl(fd: FileHandle, cmd: usize, arg: usize, token: &mut CleanLockToken)
         .get_file(fd)
         .ok_or(Error::new(EBADF))?;
 
-    let description = file.description.read(token.token());
+    let (scheme_id, number, flags) = {
+        let desc = file.description.write(token.token());
+        (desc.scheme, desc.number, desc.flags)
+    };
 
     if cmd == F_DUPFD || cmd == F_DUPFD_CLOEXEC {
         // Not in match because 'files' cannot be locked
@@ -439,15 +444,16 @@ pub fn fcntl(fd: FileHandle, cmd: usize, arg: usize, token: &mut CleanLockToken)
 
     // Communicate fcntl with scheme
     if cmd != F_GETFD && cmd != F_SETFD {
-        let scheme = scheme::get_scheme(token.token(), description.scheme)?;
+        let scheme = scheme::get_scheme(token.token(), scheme_id)?;
 
-        scheme.fcntl(description.number, cmd, arg, token)?;
+        scheme.fcntl(number, cmd, arg, token)?;
     };
 
     // Perform kernel operation if scheme agrees
     {
         let context_lock = context::current();
-        let context = context_lock.read(token.token());
+        let mut context = context_lock.read(token.token());
+        let (context, mut lock_token) = context.token_split();
 
         let mut files = context.files.write();
         match *files.get_mut(fd.get()).ok_or(Error::new(EBADF))? {
@@ -463,12 +469,10 @@ pub fn fcntl(fd: FileHandle, cmd: usize, arg: usize, token: &mut CleanLockToken)
                     file.cloexec = arg & O_CLOEXEC == O_CLOEXEC;
                     Ok(0)
                 }
-                F_GETFL => Ok(description.flags as usize),
+                F_GETFL => Ok(flags as usize),
                 F_SETFL => {
-                    let new_flags =
-                        (description.flags & O_ACCMODE as u32) | (arg as u32 & !O_ACCMODE as u32);
-                    drop(description);
-                    file.description.write(token.token()).flags = new_flags;
+                    let new_flags = (flags & O_ACCMODE as u32) | (arg as u32 & !O_ACCMODE as u32);
+                    file.description.write(lock_token.token()).flags = new_flags;
                     Ok(0)
                 }
                 _ => Err(Error::new(EINVAL)),