Revise some error numbers and messages

kernel/src/fs/exfat/inode.rs

@@ -1108,6 +1108,9 @@ impl Inode for ExfatInode {
         if inner.inode_type.is_directory() {
             return_errno!(Errno::EISDIR)
         }
+        if !inner.inode_type.is_regular_file() {
+            return_errno!(Errno::EINVAL);
+        }
 
         let file_size = inner.size;
         let fs = inner.fs();

kernel/src/fs/ext2/inode.rs

@@ -107,9 +107,12 @@ impl Inode {
     }
 
     pub fn resize(&self, new_size: usize) -> Result<()> {
-        if self.type_ != InodeType::File {
+        if self.type_ == InodeType::Dir {
             return_errno!(Errno::EISDIR);
         }
+        if self.type_ != InodeType::File {
+            return_errno!(Errno::EINVAL);
+        }
 
         let inner = self.inner.upread();
         if new_size == inner.file_size() {
@@ -782,10 +785,6 @@ impl Inode {
     }
 
     pub fn fallocate(&self, mode: FallocMode, offset: usize, len: usize) -> Result<()> {
-        if self.type_ != InodeType::File {
-            return_errno_with_message!(Errno::EISDIR, "not regular file");
-        }
-
         match mode {
             FallocMode::PunchHoleKeepSize => {
                 // Make the whole operation atomic

kernel/src/fs/inode_handle/mod.rs

@@ -406,6 +406,18 @@ pub fn do_fallocate_util(
     offset: usize,
     len: usize,
 ) -> Result<()> {
+    let inode_type = inode.type_();
+    // TODO: `fallocate` on pipe files also fails with `ESPIPE`.
+    if inode_type == InodeType::NamedPipe {
+        return_errno_with_message!(Errno::ESPIPE, "the inode is a FIFO file");
+    }
+    if !(inode_type == InodeType::File || inode_type == InodeType::Dir) {
+        return_errno_with_message!(
+            Errno::ENODEV,
+            "the inode is not a regular file or a directory"
+        );
+    }
+
     if status_flags.contains(StatusFlags::O_APPEND)
         && (mode == FallocMode::PunchHoleKeepSize
             || mode == FallocMode::CollapseRange

kernel/src/fs/overlayfs/fs.rs

@@ -414,8 +414,11 @@ impl OverlayInode {
     }
 
     pub fn resize(&self, new_size: usize) -> Result<()> {
+        if self.type_ == InodeType::Dir {
+            return_errno_with_message!(Errno::EISDIR, "the inode is a directory");
+        }
         if self.type_ != InodeType::File {
-            return_errno_with_message!(Errno::EISDIR, "not regular file");
+            return_errno_with_message!(Errno::EINVAL, "the inode is not a regular file");
         }
 
         if self.get_top_valid_inode().size() == new_size {

kernel/src/fs/ramfs/fs.rs

@@ -613,8 +613,11 @@ impl Inode for RamInode {
     }
 
     fn resize(&self, new_size: usize) -> Result<()> {
+        if self.typ == InodeType::Dir {
+            return_errno_with_message!(Errno::EISDIR, "the inode is a directory");
+        }
         if self.typ != InodeType::File {
-            return_errno_with_message!(Errno::EISDIR, "not regular file");
+            return_errno_with_message!(Errno::EINVAL, "the inode is not a regular file");
         }
 
         let file_size = self.size();
@@ -1156,10 +1159,6 @@ impl Inode for RamInode {
     }
 
     fn fallocate(&self, mode: FallocMode, offset: usize, len: usize) -> Result<()> {
-        if self.typ != InodeType::File {
-            return_errno_with_message!(Errno::EISDIR, "not regular file");
-        }
-
         // The support for flags is consistent with Linux
         match mode {
             FallocMode::Allocate => {