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v0.13.12 — Fix 1+2+4 + cross-platform SCSI parity (RIP_DESIGN.md §6, §7, §15.1)

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Fix 1: delete stall guard from Disc::copy. Pass 1 must sweep end-to-end
per ddrescue model (RIP_DESIGN.md §2.1, §3, §9). The v0.13.9 guard at
disc/mod.rs broke Pass 1 at 30% on Dune 2 with 56 GB still NonTried.
Removed stall_secs field, narrative comment in scsi/linux.rs, and the
broken regression test. Replaced with test_disc_copy_completes_full_disc_
with_failing_reader and test_disc_copy_halts_promptly_on_failing_reader.

Fix 2: async SCSI transport recovery. Added Arc<AtomicI32> fd_recovery
on SgIoTransport. On poll timeout: spawn close + spawn open in
background, return Err immediately. Top of execute() swaps fd from
recovery atomic. Main thread never blocked beyond ~1.5s poll budget
(was up to ~60s per timeout because kernel serialized main-thread
open() against in-flight close()). Drop drains pending recovery fd.

§15.1 cross-platform parity: Windows + macOS now have the same
observable recovery contract. SptiTransport gets try_recover()
(synchronous CloseHandle + CreateFileW; Windows close is fast, no
in-flight CDB drain like Linux). MacScsiTransport gets try_recover()
(release IOKit interface + reacquire via new acquire_device_iface()
helper); stores bsd_name for re-resolution. Drop guards null'd-out
interfaces. Stripped English error strings ("try as root" / "run as
administrator") on Linux + Windows. Fixed Windows TimeOutValue
ms→s ceiling so 1500ms gets 2s (was 1s; broke Drive::read fast path).

Fix 4: instrument Disc::patch arms. PatchResult exposes
blocks_attempted, blocks_read_ok, blocks_read_failed so the v0.13.11
mystery (Dune 2 Pass 2 recovered 0 bytes in 100 min) is diagnosable
from the live device log without re-instrumenting from outside.

Cleanup: honor PatchOptions::full_recovery (was read into _ and
ignored; now routed to read_sectors recovery arg). Updated
CopyOptions::batch_sectors doc to describe the actual production
path (sysfs detect_max_batch_sectors, typically 60 sectors / ~120 KB
on BU40N) rather than the test-only 32-sector internal default.

All four crates clippy-clean and tests green on the host targets
(macOS native + cargo check on Linux). Cross-platform CI watches
Linux + Windows + macOS builds + tests.
This commit is contained in:
MattJackson
2026-04-25 17:30:25 -07:00
parent 92dc145864
commit b4951b1c5b
7 changed files with 449 additions and 219 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/scsi/linux.rs
+61 -41
View File
@@ -54,8 +54,18 @@ const _: () = assert!(std::mem::size_of::<sg_io_hdr>() == 64);
pub struct SgIoTransport {
fd: i32,
device_path: std::path::PathBuf,
/// Background-recovered fd. After a poll timeout `execute()` spawns a
/// thread that closes `self.fd` and opens a fresh fd; the new fd is
/// stored here. The next call to `execute()` swaps it into `self.fd`.
/// `-1` means no recovery is ready (or the recovery open failed). See
/// RIP_DESIGN.md §7 for the design rationale.
fd_recovery: std::sync::Arc<std::sync::atomic::AtomicI32>,
}
// SgIoTransport's contained types (i32, PathBuf, Arc<AtomicI32>) are all
// Send; the auto-derived Send is intentional. Sync is NOT — callers must
// hold &mut for execute(), which the trait object dispatch enforces.
impl SgIoTransport {
/// Open a SCSI device for use. Resets the drive first to ensure
/// a known good state, then opens a fresh fd for commands.
@@ -75,6 +85,7 @@ impl SgIoTransport {
Ok(SgIoTransport {
fd,
device_path: device,
fd_recovery: std::sync::Arc::new(std::sync::atomic::AtomicI32::new(-1)),
})
}
@@ -140,10 +151,7 @@ impl SgIoTransport {
let err = std::io::Error::last_os_error();
Err(if err.kind() == std::io::ErrorKind::PermissionDenied {
Error::DevicePermission {
path: format!(
"{}: permission denied (try running as root)",
device.display()
),
path: device.display().to_string(),
}
} else {
Error::DeviceNotFound {
@@ -219,6 +227,13 @@ impl Drop for SgIoTransport {
let _ = Self::raw_command(self.fd, &[0x1E, 0, 0, 0, 0, 0], 3_000);
unsafe { libc::close(self.fd) };
}
// Drain any background-recovered fd so it doesn't leak.
let recovered = self
.fd_recovery
.swap(-1, std::sync::atomic::Ordering::Acquire);
if recovered >= 0 {
unsafe { libc::close(recovered) };
}
}
}
@@ -245,10 +260,21 @@ impl ScsiTransport for SgIoTransport {
data: &mut [u8],
timeout_ms: u32,
) -> Result<ScsiResult> {
// Recover from a prior timeout: if a background reopen produced a
// fresh fd, swap it in. If recovery is still pending (-1), the
// background thread hasn't finished — return DeviceNotFound and let
// the caller's retry loop come back later.
if self.fd < 0 {
return Err(Error::DeviceNotFound {
path: self.device_path.display().to_string(),
});
let recovered = self
.fd_recovery
.swap(-1, std::sync::atomic::Ordering::Acquire);
if recovered >= 0 {
self.fd = recovered;
} else {
return Err(Error::DeviceNotFound {
path: self.device_path.display().to_string(),
});
}
}
let mut sense = [0u8; 32];
@@ -320,43 +346,37 @@ impl ScsiTransport for SgIoTransport {
};
if pr <= 0 {
// Timeout (0) or fatal poll error (-1).
// Command is still pending in the kernel. Spawn a background
// close of the old fd (which blocks until the kernel
// completes/aborts the pending command) and open a fresh fd
// on the main thread. The main-thread open() can serialize
// against the in-flight close via the kernel's per-device
// state lock — so this call may block up to ~60 s while
// the kernel finishes the abandoned command. That's the
// cost of keeping the Drive alive across a timeout. The
// Disc::copy stall guard (v0.13.9, default 120 s of
// bytes_good non-advance) is the upper bound that prevents
// a catastrophic grind on a wedged read region.
//
// History:
// - 0.13.5 and earlier: same as this — but with no upper
// bound, hence 45-min hangs.
// - 0.13.10: tried "set fd=-1, no reopen" — too aggressive,
// one transient timeout killed the whole transport, Pass
// 1 finished in 45 ms with everything NonTrimmed.
// - 0.13.11 (this): same close+reopen as 0.13.5/8 BUT with
// the v0.13.9 stall guard ensuring Disc::copy bails out
// cleanly within 120 s of zero forward progress.
// Timeout (0) or fatal poll error (-1). Command is still pending
// in the kernel. Per RIP_DESIGN.md §4(b)/§7: close + reopen run
// in a background thread so the main thread is never blocked
// beyond the poll() budget. The recovered fd is published to
// `fd_recovery`; the next call to execute() picks it up.
let old_fd = self.fd;
self.fd = -1;
std::thread::spawn(move || {
unsafe { libc::close(old_fd) };
});
let c_path = Self::to_c_path(&self.device_path);
let new_fd = unsafe {
libc::open(
c_path.as_ptr() as *const libc::c_char,
libc::O_RDWR | libc::O_NONBLOCK | libc::O_CLOEXEC,
)
};
self.fd = if new_fd >= 0 { new_fd } else { -1 };
let recovery = self.fd_recovery.clone();
std::thread::spawn(move || {
// Close blocks until the kernel finishes/aborts the
// abandoned command. Then we open a fresh fd. Both happen
// off the main thread.
unsafe { libc::close(old_fd) };
let new_fd = unsafe {
libc::open(
c_path.as_ptr() as *const libc::c_char,
libc::O_RDWR | libc::O_NONBLOCK | libc::O_CLOEXEC,
)
};
if new_fd >= 0 {
let prev = recovery.swap(new_fd, std::sync::atomic::Ordering::Release);
if prev >= 0 {
// Stale recovery fd from a prior unclaimed attempt;
// close it so it doesn't leak.
unsafe { libc::close(prev) };
}
} else {
recovery.store(-1, std::sync::atomic::Ordering::Release);
}
});
return Err(Error::ScsiError {
opcode: cdb[0],
src/scsi/macos.rs
+71 -10
View File
@@ -175,6 +175,9 @@ const VTIDX_EXECUTE_SYNC: usize = 15;
pub struct MacScsiTransport {
device_iface: ComRef,
exclusive: bool,
/// BSD name (e.g. "disk2") retained for `try_recover()` after a
/// task-level failure. Without it we can't re-call `find_scsi_service`.
bsd_name: String,
}
// IOKit COM interface pointers are Mach port references — safe to send between threads.
@@ -195,6 +198,19 @@ impl MacScsiTransport {
dev_str
};
let device_iface = Self::acquire_device_iface(bsd_name)?;
Ok(MacScsiTransport {
device_iface,
exclusive: true,
bsd_name: bsd_name.to_string(),
})
}
/// Resolve the BSD name → IOKit SCSITaskDeviceInterface with exclusive
/// access. Shared between `open()` and `try_recover()`. Returns the
/// COM ref the caller must release.
fn acquire_device_iface(bsd_name: &str) -> Result<ComRef> {
let service = find_scsi_service(bsd_name)?;
// Create IOKit plugin for the MMC device
@@ -213,7 +229,7 @@ impl MacScsiTransport {
if kr != K_IO_RETURN_SUCCESS || plugin.is_null() {
return Err(Error::IoKitPluginFailed {
path: dev_str.to_string(),
path: bsd_name.to_string(),
kr: kr as u32,
});
}
@@ -233,7 +249,7 @@ impl MacScsiTransport {
if hr != 0 || device_iface.is_null() {
return Err(Error::ScsiInterfaceUnavailable {
path: dev_str.to_string(),
path: bsd_name.to_string(),
});
}
@@ -245,19 +261,48 @@ impl MacScsiTransport {
};
if kr != K_IO_RETURN_SUCCESS {
com_release(device_iface);
// No "Try: diskutil unmountDisk" hint — that's the CLI's job.
// The typed variant carries device path + IOReturn so the
// caller can render the right message in the right language.
return Err(Error::DeviceLocked {
path: dev_str.to_string(),
path: bsd_name.to_string(),
kr: kr as u32,
});
}
Ok(MacScsiTransport {
device_iface,
exclusive: true,
})
Ok(device_iface)
}
/// Recover the IOKit interface after a task-level failure. Releases
/// the current device_iface and re-acquires fresh state via
/// `acquire_device_iface`. Same observable contract as the Linux fd
/// recovery: after `try_recover()`, the next `execute()` either uses a
/// fresh interface or returns `DeviceNotFound` if recovery failed.
///
/// Synchronous because IOKit `RELEASE_EXCLUSIVE` + `com_release` don't
/// block on in-flight CDBs the way Linux SG_IO `close` does.
fn try_recover(&mut self) {
if !self.device_iface.is_null() {
if self.exclusive {
unsafe {
type Fn = unsafe extern "C" fn(ComRef) -> IOReturn;
let f: Fn = vtable_fn(self.device_iface, VTIDX_RELEASE_EXCLUSIVE);
f(self.device_iface);
}
self.exclusive = false;
}
com_release(self.device_iface);
self.device_iface = std::ptr::null_mut();
}
match Self::acquire_device_iface(&self.bsd_name) {
Ok(new_iface) => {
self.device_iface = new_iface;
self.exclusive = true;
}
Err(_) => {
// Leave device_iface null; next execute() returns
// DeviceNotFound. Caller's retry path will reopen Drive.
self.device_iface = std::ptr::null_mut();
self.exclusive = false;
}
}
}
// `reset()` removed in 0.13.6 — see scsi/mod.rs for rationale.
@@ -337,6 +382,9 @@ const K_SENSE_KEY_NOT_READY: u8 = 2;
impl Drop for MacScsiTransport {
fn drop(&mut self) {
if self.device_iface.is_null() {
return;
}
if self.exclusive {
unsafe {
type Fn = unsafe extern "C" fn(ComRef) -> IOReturn;
@@ -356,6 +404,15 @@ impl ScsiTransport for MacScsiTransport {
data: &mut [u8],
timeout_ms: u32,
) -> Result<ScsiResult> {
// Per RIP_DESIGN.md §15.1: parity with Linux/Windows recovery
// contract. If a prior execute() invalidated the interface and
// try_recover() also failed, fail fast.
if self.device_iface.is_null() {
return Err(Error::DeviceNotFound {
path: self.bsd_name.clone(),
});
}
// Create a SCSI task
let task: ComRef = unsafe {
type Fn = unsafe extern "C" fn(ComRef) -> ComRef;
@@ -363,6 +420,7 @@ impl ScsiTransport for MacScsiTransport {
f(self.device_iface)
};
if task.is_null() {
self.try_recover();
return Err(Error::ScsiError {
opcode: cdb[0],
status: 0xFF,
@@ -433,6 +491,9 @@ impl ScsiTransport for MacScsiTransport {
com_release(task);
if kr != K_IO_RETURN_SUCCESS {
// Task-level failure (timeout / IOKit error). Recover the
// interface so the caller's retry path can resume.
self.try_recover();
return Err(Error::ScsiError {
opcode: cdb[0],
status: 0xFF,
src/scsi/windows.rs
+71 -6
View File
@@ -85,8 +85,16 @@ unsafe extern "system" {
pub struct SptiTransport {
handle: isize,
/// Wide-encoded device path used by `try_recover()` to reopen the
/// handle after a failed DeviceIoControl. Saved from `open()` so we
/// don't have to re-resolve the device path on recovery.
wide_path: Vec<u16>,
}
// SptiTransport contains an isize HANDLE and a Vec<u16>; both Send. The
// auto-derived Send is intentional. Sync is NOT — handle mutation in
// execute() requires &mut, enforced by the trait object dispatch.
/// Normalize a device path to Windows \\.\X: format.
///
/// NOTE: A near-identical `normalize_path` exists in `drive::windows`.
@@ -129,12 +137,48 @@ impl SptiTransport {
};
if handle == INVALID_HANDLE_VALUE {
return Err(Error::DeviceNotFound {
path: format!("{}: cannot open device (run as administrator)", dev_str),
// Map last-os-error → Error variant; don't embed English hints
// in the path field (the CLI handles localization).
let err = std::io::Error::last_os_error();
return Err(if err.kind() == std::io::ErrorKind::PermissionDenied {
Error::DevicePermission {
path: dev_str.to_string(),
}
} else {
Error::DeviceNotFound {
path: dev_str.to_string(),
}
});
}
Ok(SptiTransport { handle })
Ok(SptiTransport {
handle,
wide_path: wide,
})
}
/// Recover the handle after a failed DeviceIoControl. Closes the bad
/// handle and opens a fresh one synchronously (CloseHandle/CreateFileW
/// are fast on Windows — no in-flight CDB to drain like Linux SG_IO).
/// On success, `self.handle` is replaced and the next `execute()` call
/// uses the new handle. On failure, `self.handle` is set to
/// INVALID_HANDLE_VALUE and subsequent calls return `DeviceNotFound`.
fn try_recover(&mut self) {
if self.handle != INVALID_HANDLE_VALUE {
unsafe { CloseHandle(self.handle) };
}
let new_handle = unsafe {
CreateFileW(
self.wide_path.as_ptr(),
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
std::ptr::null(),
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
std::ptr::null(),
)
};
self.handle = new_handle;
}
/// Reset the drive to a known good state.
@@ -222,8 +266,10 @@ pub(super) fn drive_has_disc(path: &Path) -> Result<bool> {
impl Drop for SptiTransport {
fn drop(&mut self) {
unsafe {
CloseHandle(self.handle);
if self.handle != INVALID_HANDLE_VALUE {
unsafe {
CloseHandle(self.handle);
}
}
}
}
@@ -236,6 +282,15 @@ impl ScsiTransport for SptiTransport {
data: &mut [u8],
timeout_ms: u32,
) -> Result<ScsiResult> {
// Per RIP_DESIGN.md §15.1: parity with Linux's recovery contract.
// If a prior call invalidated the handle and try_recover() also
// failed, fail fast.
if self.handle == INVALID_HANDLE_VALUE {
return Err(Error::DeviceNotFound {
path: String::new(),
});
}
// Zero the data buffer for reads to prevent returning uninitialized data
// if the driver doesn't fully update DataTransferLength.
if direction == DataDirection::FromDevice {
@@ -254,7 +309,11 @@ impl ScsiTransport for SptiTransport {
DataDirection::ToDevice => SCSI_IOCTL_DATA_OUT,
};
sptwb.spt.DataTransferLength = data.len() as u32;
sptwb.spt.TimeOutValue = (timeout_ms / 1000).max(1) as u32;
// Round up to the next whole second so a 1500ms request gets at
// least 2s, not 1s. SPTI's TimeOutValue is u32 seconds with no
// sub-second resolution; biasing toward "more time" is safer than
// truncating (truncation broke 1500ms fast-reads on Drive::read).
sptwb.spt.TimeOutValue = ((timeout_ms + 999) / 1000).max(1);
sptwb.spt.DataBuffer = if data.is_empty() {
std::ptr::null_mut()
} else {
@@ -280,6 +339,12 @@ impl ScsiTransport for SptiTransport {
};
if ok == 0 {
// Driver-level failure (timeout, handle gone, etc.). Recover
// the handle so the caller's retry loop can resume — same
// observable contract as Linux's async fd recovery, but
// synchronous because Windows's CloseHandle/CreateFileW don't
// block on in-flight CDBs.
self.try_recover();
return Err(Error::ScsiError {
opcode: cdb[0],
status: 0xFF,