fix(tvix/store/fuse): revert "implement open explicitly" r/6368

This reverts commit f5e291cf8328096d790f5416cf1968cb9164220a.

The offsets are relative to the start of the file, and as long as we
don't have BlobReaders implement seek, this will be very annoying to
deal with.

Change-Id: I05968f7c5c0ec0000597da90f451d6bb650c3e13
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8882
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI

1 files changed, 30 insertions, 72 deletions

diff --git a/tvix/store/src/fuse/mod.rs b/tvix/store/src/fuse/mod.rs
index 6d796534b6e6..ac0bf29dab09 100644
--- a/tvix/store/src/fuse/mod.rs
+++ b/tvix/store/src/fuse/mod.rs
@@ -18,7 +18,7 @@ use crate::{
 };
 use fuser::{FileAttr, ReplyAttr, Request};
 use nix_compat::store_path::StorePath;
-use std::io::{self, Read};
+use std::io::Read;
 use std::sync::Arc;
 use std::{collections::HashMap, time::Duration};
 use tracing::{debug, info_span, warn};
@@ -69,11 +69,6 @@ pub struct FUSE {
 
     /// This keeps track of inodes and data alongside them.
     inode_tracker: InodeTracker,
-
-    /// This holds all open file handles
-    file_handles: HashMap<u64, Box<dyn io::Read + Send>>,
-
-    next_file_handle: u64,
 }
 
 impl FUSE {
@@ -89,9 +84,6 @@ impl FUSE {
 
             store_paths: HashMap::default(),
             inode_tracker: Default::default(),
-
-            file_handles: Default::default(),
-            next_file_handle: 1,
         }
     }
 
@@ -364,10 +356,21 @@ impl fuser::Filesystem for FUSE {
         }
     }
 
-    #[tracing::instrument(skip_all, fields(rq.inode = ino))]
-    fn open(&mut self, _req: &Request<'_>, ino: u64, _flags: i32, reply: fuser::ReplyOpen) {
-        // get a new file handle
-        let fh = self.next_file_handle;
+    /// TODO: implement open + close?
+
+    #[tracing::instrument(skip_all, fields(rq.inode = ino, rq.offset = offset, rq.size = size))]
+    fn read(
+        &mut self,
+        _req: &Request<'_>,
+        ino: u64,
+        _fh: u64,
+        offset: i64,
+        size: u32,
+        _flags: i32,
+        _lock_owner: Option<u64>,
+        reply: fuser::ReplyData,
+    ) {
+        debug!("read");
 
         if ino == fuser::FUSE_ROOT_ID {
             reply.error(libc::ENOSYS);
@@ -394,71 +397,26 @@ impl fuser::Filesystem for FUSE {
                         reply.error(libc::EIO);
                     }
                     Ok(Some(blob_reader)) => {
-                        self.file_handles.insert(fh, blob_reader);
-                        reply.opened(fh, 0);
-
-                        // TODO: this will overflow after 2**64 operations,
-                        // which is fine for now.
-                        // See https://cl.tvl.fyi/c/depot/+/8834/comment/a6684ce0_d72469d1
-                        // for the discussion on alternatives.
-                        self.next_file_handle += 1;
+                        let data: std::io::Result<Vec<u8>> = blob_reader
+                            .bytes()
+                            // TODO: this is obviously terrible. blobreader should implement seek.
+                            .skip(offset.try_into().unwrap())
+                            .take(size.try_into().unwrap())
+                            .collect();
+
+                        match data {
+                            Ok(data) => {
+                                // respond with the requested data
+                                reply.data(&data);
+                            }
+                            Err(e) => reply.error(e.raw_os_error().unwrap()),
+                        }
                     }
                 }
             }
         }
     }
 
-    #[tracing::instrument(skip_all, fields(rq.inode = ino, fh = fh))]
-    fn release(
-        &mut self,
-        _req: &Request<'_>,
-        ino: u64,
-        fh: u64,
-        _flags: i32,
-        _lock_owner: Option<u64>,
-        _flush: bool,
-        reply: fuser::ReplyEmpty,
-    ) {
-        // remove and get ownership on the blob reader
-        let blob_reader = self.file_handles.remove(&fh).unwrap();
-        // drop it, which will close it.
-        drop(blob_reader);
-
-        reply.ok();
-    }
-
-    #[tracing::instrument(skip_all, fields(rq.inode = ino, rq.offset = offset, rq.size = size))]
-    fn read(
-        &mut self,
-        _req: &Request<'_>,
-        ino: u64,
-        fh: u64,
-        offset: i64,
-        size: u32,
-        _flags: i32,
-        _lock_owner: Option<u64>,
-        reply: fuser::ReplyData,
-    ) {
-        debug!("read");
-
-        let blob_reader = self.file_handles.get_mut(&fh).unwrap();
-
-        let data: std::io::Result<Vec<u8>> = blob_reader
-            .bytes()
-            // TODO: this is obviously terrible. blobreader should implement seek.
-            .skip(offset.try_into().unwrap())
-            .take(size.try_into().unwrap())
-            .collect();
-
-        match data {
-            Ok(data) => {
-                // respond with the requested data
-                reply.data(&data);
-            }
-            Err(e) => reply.error(e.raw_os_error().unwrap()),
-        }
-    }
-
     #[tracing::instrument(skip_all, fields(rq.inode = ino))]
     fn readlink(&mut self, _req: &Request<'_>, ino: u64, reply: fuser::ReplyData) {
         if ino == fuser::FUSE_ROOT_ID {