switch to 2021 edition of Rust (openzfs#21)

Make 2 changes that are not strictly required but make sense given the
changes in the 2021 edition:

1. TryFrom/TryInto no longer need to be imported, as they are part of
the standard prelude.  Remove the redundant `use` statements.

2. When possible, closures capture members of local variables, rather
than the entire variable.  This can cause the non-captured members to be
dropped later than in the 2018 edition.  In our case (in
ZettaCache::open()), this doesn't really matter, but it brought to my
attention that we're cloning and then discarding a bunch of the members
of ZettaCache (without using them).  So I changed this to just clone the
few members that are actually needed by the closures.

cmd/zfs_object_agent/client/Cargo.toml

@@ -2,7 +2,7 @@
 name = "zoa_test"
 version = "0.1.0"
 authors = ["Delphix"]
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 

cmd/zfs_object_agent/object_perf/Cargo.toml

@@ -2,7 +2,7 @@
 name = "zfs_object_perf"
 version = "0.1.0"
 authors = ["Delphix"]
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
@@ -15,4 +15,4 @@ futures = "0.3.16"
 serde = { version = "1.0.125", features = ["derive"] }
 uuid = {version = "0.8"}
 tokio = { version = "1.4", features = ["full"] }
-zettaobject = { path = "../zettaobject" }
+zettaobject = { path = "../zettaobject" }

cmd/zfs_object_agent/object_perf/src/s3perf.rs

@@ -6,7 +6,6 @@ use metered::hdr_histogram::AtomicHdrHistogram;
 use metered::metered;
 use metered::time_source::StdInstantMicros;
 use std::cmp::max;
-use std::convert::TryInto;
 use std::error::Error;
 use std::string::String;
 use std::sync::Arc;

cmd/zfs_object_agent/server/Cargo.toml

@@ -2,7 +2,7 @@
 name = "zfs_object_agent"
 version = "0.1.0"
 authors = ["Delphix"]
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 

cmd/zfs_object_agent/util/Cargo.toml

@@ -2,7 +2,7 @@
 name = "util"
 version = "0.1.0"
 authors = ["Delphix"]
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 [dependencies]

cmd/zfs_object_agent/util/src/from64.rs

@@ -1,5 +1,3 @@
-use std::convert::TryInto;
-
 /// Conversions that are safe assuming that we are on LP64 (usize == u64)
 pub trait From64<A> {
     fn from64(a: A) -> Self;

cmd/zfs_object_agent/zcdb/Cargo.toml

@@ -2,7 +2,7 @@
 name = "zcachedb"
 version = "0.1.0"
 authors = ["Delphix"]
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
@@ -12,4 +12,4 @@ git-version = "0.3.5"
 libc = "0.2"
 log = "0.4"
 tokio = { version = "1.4", features = ["full"] }
-zettacache = { path = "../zettacache" }
+zettacache = { path = "../zettacache" }

cmd/zfs_object_agent/zettacache/Cargo.toml

@@ -2,7 +2,7 @@
 name = "zettacache"
 version = "0.1.0"
 authors = ["Delphix"]
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 

cmd/zfs_object_agent/zettacache/src/block_access.rs

@@ -15,8 +15,6 @@ use num::Num;
 use num::NumCast;
 use serde::de::DeserializeOwned;
 use serde::{Deserialize, Serialize};
-use std::convert::TryFrom;
-use std::convert::TryInto;
 use std::io::Read;
 use std::io::Write;
 use std::os::unix::prelude::AsRawFd;

cmd/zfs_object_agent/zettacache/src/block_allocator.rs

@@ -10,7 +10,6 @@ use roaring::RoaringBitmap;
 use serde::{Deserialize, Serialize};
 use std::cmp::{self, min};
 use std::collections::{BTreeMap, BTreeSet, HashSet};
-use std::convert::TryFrom;
 use std::ops::Bound::*;
 use std::sync::Arc;
 use std::time::Instant;

cmd/zfs_object_agent/zettacache/src/zettacache.rs

@@ -27,7 +27,6 @@ use more_asserts::*;
 use serde::{Deserialize, Serialize};
 use std::collections::btree_map;
 use std::collections::BTreeMap;
-use std::convert::TryFrom;
 use std::ops::Bound::{Excluded, Unbounded};
 use std::pin::Pin;
 use std::sync::Arc;
@@ -685,17 +684,18 @@ impl ZettaCache {
             my_cache.checkpoint_task(merge_rx, merge_index).await;
         });
 
-        let my_cache = this.clone();
+        let state = this.state.clone();
+        let metrics = this.metrics.clone();
         tokio::spawn(async move {
             let mut interval = tokio::time::interval(Duration::from_secs(10));
             loop {
                 interval.tick().await;
-                debug!("metrics: {:#?}", my_cache.metrics);
-                my_cache.state.lock().await.block_access.dump_metrics();
+                debug!("metrics: {:#?}", metrics);
+                state.lock().await.block_access.dump_metrics();
             }
         });
 
-        let my_cache = this.clone();
+        let state = this.state.clone();
         tokio::spawn(async move {
             // XXX maybe we should bump the atime after a set number of
             // accesses, so each histogram bucket starts with the same count.
@@ -704,7 +704,7 @@ impl ZettaCache {
             let mut interval = tokio::time::interval(Duration::from_secs(10));
             loop {
                 interval.tick().await;
-                let mut state = my_cache.state.lock().await;
+                let mut state = state.lock().await;
                 state.atime = state.atime.next();
             }
         });

cmd/zfs_object_agent/zettaobject/Cargo.toml

@@ -2,7 +2,7 @@
 name = "zettaobject"
 version = "0.1.0"
 authors = ["Delphix"]
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 

cmd/zfs_object_agent/zettaobject/src/data_object.rs

@@ -6,7 +6,6 @@ use log::*;
 use more_asserts::*;
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
-use std::convert::{TryFrom, TryInto};
 use std::fmt;
 use std::fmt::Display;
 use std::time::Instant;

cmd/zfs_object_agent/zettaobject/src/object_access.rs

@@ -22,7 +22,6 @@ use rusoto_s3::{
     ListObjectsV2Request, ObjectIdentifier, PutObjectError, PutObjectOutput, PutObjectRequest,
     S3Client, S3,
 };
-use std::convert::TryFrom;
 use std::error::Error;
 use std::fmt::Formatter;
 use std::iter;

cmd/zfs_object_agent/zettaobject/src/pool.rs

@@ -38,7 +38,6 @@ use std::borrow::Borrow;
 use std::cmp::{max, min};
 use std::collections::hash_map;
 use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
-use std::convert::{TryFrom, TryInto};
 use std::fmt;
 use std::fmt::Display;
 use std::mem;

cmd/zfs_object_agent/zoa/Cargo.toml

@@ -2,7 +2,7 @@
 name = "zoa"
 version = "0.1.0"
 authors = ["Delphix"]
-edition = "2018"
+edition = "2021"
 build = "src/build.rs"
 
 [build-dependencies]