From c4fabc7c801491019263523df3c9078cca99bb6e Mon Sep 17 00:00:00 2001

From: Nikita Dubrovskii <nikita@linux.ibm.com>

Date: Wed, 2 Jun 2021 14:27:42 +0200

Subject: [PATCH] s390: add support for virtio dasds

This is a fix for https://bugzilla.redhat.com/show_bug.cgi?id=1960485

Signed-off-by: Nikita Dubrovskii <nikita@linux.ibm.com>

---

 src/blockdev.rs   | 30 ++++++++++++++++++++++++++++--

 src/cmdline.rs    |  2 +-

 src/install.rs    |  6 +++---

 src/s390x/dasd.rs | 15 +++++++++++----

 4 files changed, 43 insertions(+), 10 deletions(-)

diff --git a/src/blockdev.rs b/src/blockdev.rs

index 90c6bee..df8e10a 100644

--- a/src/blockdev.rs

+++ b/src/blockdev.rs

@@ -970,10 +970,36 @@ pub fn detect_formatted_sector_size(buf: &[u8]) -> Option<NonZeroU32> {

 }

 /// Checks if underlying device is IBM DASD disk

-pub fn is_dasd(device: &str) -> Result<bool> {

+pub fn is_dasd(device: &str, fd: Option<&mut File>) -> Result<bool> {

     let target =

         canonicalize(device).with_context(|| format!("getting absolute path to {}", device))?;

-    Ok(target.to_string_lossy().starts_with("/dev/dasd"))

+    if target.to_string_lossy().starts_with("/dev/dasd") {

+        return Ok(true);

+    }

+    let read_magic = |device: &str, disk: &mut File| -> Result<[u8; 4]> {

+        let offset = disk

+            .seek(SeekFrom::Current(0))

+            .with_context(|| format!("saving offset {}", device))?;

+        disk.seek(SeekFrom::Start(8194))

+            .with_context(|| format!("seeking {}", device))?;

+        let mut lbl = [0u8; 4];

+        disk.read_exact(&mut lbl)

+            .with_context(|| format!("reading label {}", device))?;

+        disk.seek(SeekFrom::Start(offset))

+            .with_context(|| format!("restoring offset {}", device))?;

+        Ok(lbl)

+    };

+    if target.to_string_lossy().starts_with("/dev/vd") {

+        let cdl_magic = [0xd3, 0xf1, 0xe5, 0xd6];

+        let lbl = if let Some(t) = fd {

+            read_magic(device, t)?

+        } else {

+            let mut disk = File::open(device).with_context(|| format!("opening {}", device))?;

+            read_magic(device, &mut disk)?

+        };

+        return Ok(cdl_magic == lbl);

+    }

+    Ok(false)

 }

 // create unsafe ioctl wrappers

diff --git a/src/cmdline.rs b/src/cmdline.rs

index db3d1d0..53b8179 100644

--- a/src/cmdline.rs

+++ b/src/cmdline.rs

@@ -853,7 +853,7 @@ fn parse_install(matches: &ArgMatches) -> Result<Config> {

     // it changes to the recommended 4096

     // https://bugzilla.redhat.com/show_bug.cgi?id=1905159

     #[allow(clippy::match_bool, clippy::match_single_binding)]

-    let sector_size = match is_dasd(&device)

+    let sector_size = match is_dasd(&device, None)

         .with_context(|| format!("checking whether {} is an IBM DASD disk", device))?

     {

         #[cfg(target_arch = "s390x")]

diff --git a/src/install.rs b/src/install.rs

index baa3880..20d1f41 100644

--- a/src/install.rs

+++ b/src/install.rs

@@ -47,7 +47,7 @@ pub fn install(config: &InstallConfig) -> Result<()> {

     #[cfg(target_arch = "s390x")]

     {

-        if is_dasd(&config.device)? {

+        if is_dasd(&config.device, None)? {

             if !config.save_partitions.is_empty() {

                 // The user requested partition saving, but SavedPartitions

                 // doesn't understand DASD VTOCs and won't find any partitions

@@ -156,7 +156,7 @@ fn write_disk(

     // copy the image

     #[allow(clippy::match_bool, clippy::match_single_binding)]

-    let image_copy = match is_dasd(&config.device)? {

+    let image_copy = match is_dasd(&config.device, Some(dest))? {

         #[cfg(target_arch = "s390x")]

         true => s390x::image_copy_s390x,

         _ => image_copy_default,

@@ -527,7 +527,7 @@ fn reset_partition_table(

 ) -> Result<()> {

     eprintln!("Resetting partition table");

-    if is_dasd(&config.device)? {

+    if is_dasd(&config.device, Some(dest))? {

         // Don't write out a GPT, since the backup GPT may overwrite

         // something we're not allowed to touch.  Just clear the first MiB

         // of disk.

diff --git a/src/s390x/dasd.rs b/src/s390x/dasd.rs

index 7145071..b7dea78 100644

--- a/src/s390x/dasd.rs

+++ b/src/s390x/dasd.rs

@@ -35,13 +35,15 @@ pub(crate) struct Range {

     pub length: u64,

 }

-/// There are 2 types of DASD devices:

+/// There are 3 types of DASD devices:

 ///   - ECKD (Extended Count Key Data) - is regular DASD of type 3390

 ///   - FBA (Fixed Block Access) - is used for emulated device that represents a real SCSI device

+///   - Virt - ECKD on LPAR/zKVM as virtio-device

 /// Only ECKD disks require `dasdfmt, fdasd` linux tools to be configured.

 enum DasdType {

     Eckd,

     Fba,

+    Virt,

 }

 fn get_dasd_type<P: AsRef<Path>>(device: P) -> Result<DasdType> {

@@ -53,6 +55,9 @@ fn get_dasd_type<P: AsRef<Path>>(device: P) -> Result<DasdType> {

         .with_context(|| format!("getting name of {}", device.display()))?

         .to_string_lossy()

         .to_string();

+    if device.starts_with("vd") {

+        return Ok(DasdType::Virt);

+    }

     let devtype_path = format!("/sys/class/block/{}/device/devtype", device);

     let devtype_str = std::fs::read_to_string(&devtype_path)

         .with_context(|| format!("reading {}", devtype_path))?;

@@ -66,7 +71,7 @@ fn get_dasd_type<P: AsRef<Path>>(device: P) -> Result<DasdType> {

 pub fn prepare_dasd(dasd: &str) -> Result<()> {

     match get_dasd_type(dasd)? {

         DasdType::Eckd => eckd_prepare(dasd),

-        DasdType::Fba => Ok(()),

+        DasdType::Fba | DasdType::Virt => Ok(()),

     }

 }

@@ -75,7 +80,7 @@ pub fn prepare_dasd(dasd: &str) -> Result<()> {

 pub fn dasd_try_get_sector_size(dasd: &str) -> Result<Option<NonZeroU32>> {

     match get_dasd_type(dasd)? {

         DasdType::Eckd => eckd_try_get_sector_size(dasd),

-        DasdType::Fba => Ok(None),

+        DasdType::Fba | DasdType::Virt => Ok(None),

     }

 }

@@ -87,8 +92,10 @@ pub fn image_copy_s390x(

     _saved: Option<&SavedPartitions>,

 ) -> Result<()> {

     let ranges = match get_dasd_type(dest_path)? {

-        DasdType::Eckd => eckd_make_partitions(&dest_path.to_string_lossy(), dest_file, first_mb)?,

         DasdType::Fba => fba_make_partitions(&dest_path.to_string_lossy(), dest_file, first_mb)?,

+        DasdType::Eckd | DasdType::Virt => {

+            eckd_make_partitions(&dest_path.to_string_lossy(), dest_file, first_mb)?

+        }

     };

     // copy each partition

-- 

2.31.1