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fix #3743: extract zfs dataset io stats from /proc/spl/kstat/zfs/POOL/objset-* 

Recently, ZFS removed the pool global io stats from
/proc/spl/kstat/zfs/POOL/io with no replacement.

To gather stats about the datastores, access now the objset specific
entries there. To be able to make that efficient, cache a map of
dataset <-> obset ids, so that we do not have to parse all files each time.

We update the cache each time we try to get the info for a dataset
where we do not have a mapping.

We cannot update it on datastore add/remove since that happens in the
proxmox-backup daemon, while we need the info here in proxmox-backup-proxy.

Sadly with this we lose the io wait metric, but it seems that this is no
longer tracked in zfs at all, so nothing we can do for that.

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
This commit is contained in:
Dominik Csapak 2022-01-10 12:08:14 +01:00 committed by Dietmar Maurer
parent b44483a853
commit 7c069e82d1
2 changed files with 125 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
src/bin/proxmox-backup-proxy.rs
View File

@ -62,8 +62,7 @@ use proxmox_backup::tools::{
PROXMOX_BACKUP_TCP_KEEPALIVE_TIME,
disks::{
DiskManage,
zfs_pool_stats,
get_pool_from_dataset,
zfs_dataset_stats,
},
};
@ -1072,16 +1071,16 @@ fn gather_disk_stats(disk_manager: Arc<DiskManage>, path: &Path, rrd_prefix: &st
Ok(None) => {},
Ok(Some((fs_type, device, source))) => {
let mut device_stat = None;
match fs_type.as_str() {
"zfs" => {
if let Some(source) = source {
let pool = get_pool_from_dataset(&source).unwrap_or(&source);
match zfs_pool_stats(pool) {
Ok(stat) => device_stat = stat,
Err(err) => eprintln!("zfs_pool_stats({:?}) failed - {}", pool, err),
}
match (fs_type.as_str(), source) {
("zfs", Some(source)) => match source.into_string() {
Ok(dataset) => match zfs_dataset_stats(&dataset) {
Ok(stat) => device_stat = Some(stat),
Err(err) => eprintln!("zfs_dataset_stats({:?}) failed - {}", dataset, err),
},
Err(source) => {
eprintln!("zfs_pool_stats({:?}) failed - invalid characters", source)
}
}
},
_ => {
if let Ok(disk) = disk_manager.clone().disk_by_dev_num(device.into_dev_t()) {
match disk.read_stat() {

123
src/tools/disks/zfs.rs
View File

@ -1,10 +1,13 @@
use std::path::PathBuf;
use std::collections::HashSet;
use std::os::unix::fs::MetadataExt;
use std::sync::{Arc, Mutex};
use anyhow::{bail, Error};
use lazy_static::lazy_static;
use proxmox_schema::const_regex;
use super::*;
lazy_static!{
@ -16,15 +19,12 @@ lazy_static!{
};
}
/// returns pool from dataset path of the form 'rpool/ROOT/pbs-1'
pub fn get_pool_from_dataset(dataset: &OsStr) -> Option<&OsStr> {
if let Some(dataset) = dataset.to_str() {
if let Some(idx) = dataset.find('/') {
return Some(dataset[0..idx].as_ref());
}
fn get_pool_from_dataset(dataset: &str) -> &str {
if let Some(idx) = dataset.find('/') {
&dataset[0..idx].as_ref()
} else {
dataset.as_ref()
}
None
}
/// Returns kernel IO-stats for zfs pools
@ -97,3 +97,110 @@ pub fn zfs_devices(
Ok(device_set)
}
const ZFS_KSTAT_BASE_PATH: &str = "/proc/spl/kstat/zfs";
const_regex! {
OBJSET_REGEX = r"^objset-0x[a-fA-F0-9]+$";
}
lazy_static::lazy_static! {
pub static ref ZFS_DATASET_OBJSET_MAP: Arc<Mutex<HashMap<String, (String, String)>>> =
Arc::new(Mutex::new(HashMap::new()));
}
// parses /proc/spl/kstat/zfs/POOL/objset-ID files
// they have the following format:
//
// 0 0 0x00 0 0000 00000000000 000000000000000000
// name type data
// dataset_name 7 pool/dataset
// writes 4 0
// nwritten 4 0
// reads 4 0
// nread 4 0
// nunlinks 4 0
// nunlinked 4 0
//
// we are only interested in the dataset_name, writes, nwrites, reads and nread
fn parse_objset_stat(pool: &str, objset_id: &str) -> Result<(String, BlockDevStat), Error> {
let path = PathBuf::from(format!("{}/{}/{}", ZFS_KSTAT_BASE_PATH, pool, objset_id));
let text = match proxmox_sys::fs::file_read_optional_string(&path)? {
Some(text) => text,
None => bail!("could not parse 'objset-{}' stat file", objset_id),
};
let mut dataset_name = String::new();
let mut stat = BlockDevStat {
read_sectors: 0,
write_sectors: 0,
read_ios: 0,
write_ios: 0,
io_ticks: 0,
};
for (i, line) in text.lines().enumerate() {
if i < 2 {
continue;
}
let mut parts = line.split_ascii_whitespace();
let name = parts.next();
parts.next(); // discard type
let value = parts.next().ok_or_else(|| format_err!("no value found"))?;
match name {
Some("dataset_name") => dataset_name = value.to_string(),
Some("writes") => stat.write_ios = u64::from_str_radix(value, 10).unwrap_or(0),
Some("nwritten") => {
stat.write_sectors = u64::from_str_radix(value, 10).unwrap_or(0) / 512
}
Some("reads") => stat.read_ios = u64::from_str_radix(value, 10).unwrap_or(0),
Some("nread") => stat.read_sectors = u64::from_str_radix(value, 10).unwrap_or(0) / 512,
_ => {}
}
}
Ok((dataset_name, stat))
}
fn get_mapping(dataset: &str) -> Option<(String, String)> {
ZFS_DATASET_OBJSET_MAP
.lock()
.unwrap()
.get(dataset)
.map(|c| c.to_owned())
}
/// Updates the dataset <-> objset_map
pub(crate) fn update_zfs_objset_map(pool: &str) -> Result<(), Error> {
let mut map = ZFS_DATASET_OBJSET_MAP.lock().unwrap();
map.clear();
let path = PathBuf::from(format!("{}/{}", ZFS_KSTAT_BASE_PATH, pool));
proxmox_sys::fs::scandir(
libc::AT_FDCWD,
&path,
&OBJSET_REGEX,
|_l2_fd, filename, _type| {
let (name, _) = parse_objset_stat(pool, filename)?;
map.insert(name, (pool.to_string(), filename.to_string()));
Ok(())
},
)?;
Ok(())
}
/// Gets io stats for the dataset from /proc/spl/kstat/zfs/POOL/objset-ID
pub fn zfs_dataset_stats(dataset: &str) -> Result<BlockDevStat, Error> {
let mut mapping = get_mapping(dataset);
if mapping.is_none() {
let pool = get_pool_from_dataset(dataset);
update_zfs_objset_map(pool)?;
mapping = get_mapping(dataset);
}
let (pool, objset_id) =
mapping.ok_or_else(|| format_err!("could not find objset id for dataset"))?;
let (_, stat) = parse_objset_stat(&pool, &objset_id)?;
Ok(stat)
}