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optical vs block batch sizing

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This commit is contained in:
MattJackson
2026-05-11 15:35:45 -07:00
parent 4fd5d27df8
commit 8238ec4ce7
1 changed files with 51 additions and 30 deletions
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src/disc/mod.rs
+51 -30
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@@ -1545,7 +1545,7 @@ impl Disc {
let batch: u16 = match opts.batch_sectors {
Some(b) => b,
None if opts.skip_on_error => ecc_sectors(self.format),
None => DEFAULT_BATCH_SECTORS,
None => DEFAULT_BATCH_SECTORS_OPTICAL,
};
// Pre-compute the list of NonTried regions before handing the
@@ -3327,7 +3327,8 @@ impl Disc {
}
const MAX_BATCH_SECTORS: u16 = 510;
const DEFAULT_BATCH_SECTORS: u16 = 60;
const DEFAULT_BATCH_SECTORS_OPTICAL: u16 = 60;
const DEFAULT_BATCH_SECTORS_BLOCK: u16 = 8192;
const MIN_BATCH_SECTORS: u16 = 3;
pub(crate) fn ecc_sectors(format: DiscFormat) -> u16 {
@@ -3404,43 +3405,63 @@ mod severity_tests {
}
/// Detect the maximum transfer size in sectors for a device.
/// Reads /sys/block/<dev>/queue/max_hw_sectors_kb on Linux.
/// For sg devices, resolves the corresponding block device via sysfs.
/// Returns a value aligned to 3 sectors (one aligned unit).
pub fn detect_max_batch_sectors(device_path: &str) -> u16 {
let dev_name = device_path.rsplit('/').next().unwrap_or("");
if dev_name.is_empty() {
return DEFAULT_BATCH_SECTORS;
return DEFAULT_BATCH_SECTORS_OPTICAL;
}
// For sg devices, find the corresponding block device name
let block_name = if dev_name.starts_with("sg") {
let block_dir = format!("/sys/class/scsi_generic/{dev_name}/device/block");
std::fs::read_dir(&block_dir)
.ok()
.and_then(|mut entries| entries.next())
.and_then(|e| e.ok())
.map(|e| e.file_name().to_string_lossy().to_string())
} else {
Some(dev_name.to_string())
};
if let Some(bname) = block_name {
let sysfs_path = format!("/sys/block/{bname}/queue/max_hw_sectors_kb");
if let Ok(content) = std::fs::read_to_string(&sysfs_path) {
if let Ok(kb) = content.trim().parse::<u32>() {
// Convert KB to sectors (1 sector = 2 KB = 2048 bytes)
let sectors = (kb / 2) as u16;
// Align down to 3 (one aligned unit)
let aligned = (sectors / 3) * 3;
if aligned >= MIN_BATCH_SECTORS {
return aligned.min(MAX_BATCH_SECTORS);
// Check if optical drive (0x05 = CD/DVD)
let is_optical = (|| -> bool {
use std::path::Path;
let scsi_device_dir = format!("/sys/class/scsi_device/");
if let Ok(entries) = std::fs::read_dir(&scsi_device_dir) {
for entry in entries.flatten() {
let device_type_path = entry.path().join("device/type");
if Path::new(&device_type_path).exists() {
if let Ok(content) = std::fs::read_to_string(&device_type_path) {
// Type 0x05 (decimal 5) = CD/DVD drive
if content.trim().parse::<u32>() == Ok(5) {
return true;
}
}
}
}
}
false
})();
if is_optical {
// For sg devices, find the corresponding block device name
let block_name = if dev_name.starts_with("sg") {
let block_dir = format!("/sys/class/scsi_generic/{dev_name}/device/block");
std::fs::read_dir(&block_dir)
.ok()
.and_then(|mut entries| entries.next())
.and_then(|e| e.ok())
.map(|e| e.file_name().to_string_lossy().to_string())
} else {
Some(dev_name.to_string())
};
if let Some(bname) = block_name {
let sysfs_path = format!("/sys/block/{bname}/queue/max_hw_sectors_kb");
if let Ok(content) = std::fs::read_to_string(&sysfs_path) {
if let Ok(kb) = content.trim().parse::<u32>() {
// Convert KB to sectors (1 sector = 2 KB = 2048 bytes)
let sectors = (kb / 2) as u16;
// Align down to 3 (one aligned unit)
let aligned = (sectors / 3) * 3;
if aligned >= MIN_BATCH_SECTORS {
return aligned.min(MAX_BATCH_SECTORS);
}
}
}
}
DEFAULT_BATCH_SECTORS_OPTICAL
} else {
DEFAULT_BATCH_SECTORS_BLOCK
}
// Fallback: safe default well under typical kernel limits
DEFAULT_BATCH_SECTORS
}
// ─── Format helpers ────────────────────────────────────────────────────────