src/tools/disks/zfs.rs: helper to read zfs pool io stats

src/tools/disks.rs

@@ -16,6 +16,8 @@ use proxmox::sys::error::io_err_other;
 use proxmox::sys::linux::procfs::MountInfo;
 use proxmox::{io_bail, io_format_err};
 
+pub mod zfs;
+
 bitflags! {
     /// Ways a device is being used.
     pub struct DiskUse: u32 {

src/tools/disks/zfs.rs

@@ -0,0 +1,47 @@
+use anyhow::{bail, Error};
+
+use std::path::PathBuf;
+
+use super::*;
+
+pub fn zfs_pool_stats(pool: &OsStr) -> Result<Option<BlockDevStat>, Error> {
+
+    let mut path = PathBuf::from("/proc/spl/kstat/zfs");
+    path.push(pool);
+    path.push("io");
+
+    let text = match proxmox::tools::fs::file_read_optional_string(&path)? {
+        Some(text) => text,
+        None => { return Ok(None); }
+    };
+
+    let lines: Vec<&str> = text.lines().collect();
+
+    if lines.len() < 3 {
+        bail!("unable to parse {:?} - got less than 3 lines", path);
+    }
+
+    // https://github.com/openzfs/zfs/blob/master/lib/libspl/include/sys/kstat.h#L578
+    // nread    nwritten reads    writes   wtime    wlentime wupdate  rtime    rlentime rupdate  wcnt     rcnt
+    // Note: w -> wait (wtime -> wait time)
+    // Note: r -> run  (rtime -> run time)
+    // All times are nanoseconds
+    let stat: Vec<u64> = lines[2].split_ascii_whitespace().map(|s| {
+        u64::from_str_radix(s, 10).unwrap_or(0)
+    }).collect();
+
+    let ticks = stat[4]/1_000_000; // convert to milisec
+
+    let stat = BlockDevStat {
+        read_sectors: stat[0]>>9,
+        write_sectors: stat[1]>>9,
+        read_ios: stat[2],
+        write_ios: stat[3],
+        read_merges: 0, // there is no such info
+        write_merges: 0, // there is no such info
+        write_ticks: ticks,
+        read_ticks: ticks,
+    };
+
+    Ok(Some(stat))
+}