[RFC PATCH v2 10/10] rust: puzzlefs: add oci_root_dir and image_manifest filesystem parameters

[Ariel Miculas <amiculas@xxxxxxxxx>]

These parameters are passed when mounting puzzlefs using '-o' option of
mount:
-o oci_root_dir="/path/to/oci/dir"
-o image_manifest="root_hash_of_image_manifest"

For a particular manifest in the manifests array in index.json (located
in the oci_root_dir), the root hash of the image manifest is found in
the digest field.

It would be nicer if we could pass the tag, but we don't support json
deserialization.

Example of mount:
mount -t puzzlefs -o oci_root_dir="/home/puzzlefs_oci" -o \
image_manifest="2d6602d678140540dc7e96de652a76a8b16e8aca190bae141297bcffdcae901b" \
none /mnt

Signed-off-by: Ariel Miculas <amiculas@xxxxxxxxx>
---
 samples/rust/puzzlefs.rs | 63 ++++++++++++++++++++++++++--------------
 1 file changed, 41 insertions(+), 22 deletions(-)

diff --git a/samples/rust/puzzlefs.rs b/samples/rust/puzzlefs.rs
index dad7ecc76eca..4e9a8aedf0c1 100644
--- a/samples/rust/puzzlefs.rs
+++ b/samples/rust/puzzlefs.rs
@@ -7,6 +7,7 @@
 use kernel::{
     c_str, file, fs,
     io_buffer::IoBufferWriter,
+    str::CString,
     sync::{Arc, ArcBorrow},
 };
 
@@ -31,27 +32,29 @@ struct PuzzlefsInfo {
     puzzlefs: Arc<PuzzleFS>,
 }
 
+#[derive(Default)]
+struct PuzzleFsParams {
+    oci_root_dir: Option<CString>,
+    image_manifest: Option<CString>,
+}
+
 #[vtable]
 impl fs::Context<Self> for PuzzleFsModule {
-    type Data = ();
-
-    kernel::define_fs_params! {(),
-        {flag, "flag", |_, v| { pr_info!("flag passed-in: {v}\n"); Ok(()) } },
-        {flag_no, "flagno", |_, v| { pr_info!("flagno passed-in: {v}\n"); Ok(()) } },
-        {bool, "bool", |_, v| { pr_info!("bool passed-in: {v}\n"); Ok(()) } },
-        {u32, "u32", |_, v| { pr_info!("u32 passed-in: {v}\n"); Ok(()) } },
-        {u32oct, "u32oct", |_, v| { pr_info!("u32oct passed-in: {v}\n"); Ok(()) } },
-        {u32hex, "u32hex", |_, v| { pr_info!("u32hex passed-in: {v}\n"); Ok(()) } },
-        {s32, "s32", |_, v| { pr_info!("s32 passed-in: {v}\n"); Ok(()) } },
-        {u64, "u64", |_, v| { pr_info!("u64 passed-in: {v}\n"); Ok(()) } },
-        {string, "string", |_, v| { pr_info!("string passed-in: {v}\n"); Ok(()) } },
-        {enum, "enum", [("first", 10), ("second", 20)], |_, v| {
-            pr_info!("enum passed-in: {v}\n"); Ok(()) }
-        },
+    type Data = Box<PuzzleFsParams>;
+
+    kernel::define_fs_params! {Box<PuzzleFsParams>,
+        {string, "oci_root_dir", |s, v| {
+                                      s.oci_root_dir = Some(CString::try_from_fmt(format_args!("{v}"))?);
+                                      Ok(())
+                                  }},
+        {string, "image_manifest", |s, v| {
+                                      s.image_manifest = Some(CString::try_from_fmt(format_args!("{v}"))?);
+                                      Ok(())
+                                  }},
     }
 
-    fn try_new() -> Result {
-        Ok(())
+    fn try_new() -> Result<Self::Data> {
+        Ok(Box::try_new(PuzzleFsParams::default())?)
     }
 }
 
@@ -136,11 +139,27 @@ impl fs::Type for PuzzleFsModule {
     const FLAGS: i32 = fs::flags::USERNS_MOUNT;
     const DCACHE_BASED: bool = true;
 
-    fn fill_super(_data: (), sb: fs::NewSuperBlock<'_, Self>) -> Result<&fs::SuperBlock<Self>> {
-        let puzzlefs = PuzzleFS::open(
-            c_str!("/home/puzzlefs_oci"),
-            c_str!("2d6602d678140540dc7e96de652a76a8b16e8aca190bae141297bcffdcae901b"),
-        );
+    fn fill_super(
+        data: Box<PuzzleFsParams>,
+        sb: fs::NewSuperBlock<'_, Self>,
+    ) -> Result<&fs::SuperBlock<Self>> {
+        let oci_root_dir = match data.oci_root_dir {
+            Some(val) => val,
+            None => {
+                pr_err!("missing oci_root_dir parameter!\n");
+                return Err(ENOTSUPP);
+            }
+        };
+
+        let image_manifest = match data.image_manifest {
+            Some(val) => val,
+            None => {
+                pr_err!("missing image_manifest parameter!\n");
+                return Err(ENOTSUPP);
+            }
+        };
+
+        let puzzlefs = PuzzleFS::open(&oci_root_dir, &image_manifest);
 
         if let Err(ref e) = puzzlefs {
             pr_info!("error opening puzzlefs {e}\n");
-- 
2.41.0