feature/CSTACKEX-310: implement all method for ontap iscsi adapter (#105)

…d removed changes from common iscsiadmstorageadpater

### Description

This PR...
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### Types of changes

- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] Enhancement (improves an existing feature and functionality)
- [ ] Cleanup (Code refactoring and cleanup, that may add test cases)
- [ ] Build/CI
- [ ] Test (unit or integration test code)

### Feature/Enhancement Scale or Bug Severity

#### Feature/Enhancement Scale

- [ ] Major
- [ ] Minor

#### Bug Severity

- [ ] BLOCKER
- [ ] Critical
- [ ] Major
- [ ] Minor
- [ ] Trivial

### Screenshots (if appropriate):

### How Has This Been Tested?
Tested happy path testing in ubunut VM. All workflows working fine.
Create zone->Pod-> Cluster->Host->Primary Storage->Secondary Storage.

iSCSI

Create Storage Pool - PASS

Create disk and compute offering for the storage pool using only the
tag. - PASS

Create VM instance using the same disk and compute offering. - PASS

Power Off the VM. - PASS

Power on the VM on the same host again. - PASS

Destroy the VM without expunge and no data volume selected. - PASS

Attach the disk/volume to a already running VM. - PASS

Detach the disk/volume from a running VM. - PASS

Destroy the volume without expunge.  - PASS

Recover the destroyed volume again. - PASS

Destroy the VM without expunge and all data volume selected.- PASS

Destroy the VM with expunge and all data volume selected.- PASS

Take instance snapshot without quiesce and without memory.- PASS

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#### How did you try to break this feature and the system with this
change?

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---------

Co-authored-by: Srivastava, Piyush <Piyush.Srivastava@netapp.com>

Author: piyush5netapp

plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/storage/IscsiAdmStorageAdaptor.java

@@ -16,14 +16,9 @@
 // under the License.
 package com.cloud.hypervisor.kvm.storage;
 
-import java.io.File;
-import java.io.FileWriter;
-import java.nio.file.Path;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.nio.file.Files;
-import java.nio.file.Paths;
 
 import org.apache.cloudstack.utils.qemu.QemuImg;
 import org.apache.cloudstack.utils.qemu.QemuImg.PhysicalDiskFormat;
@@ -47,12 +42,6 @@ public class IscsiAdmStorageAdaptor implements StorageAdaptor {
 
     private static final Map<String, KVMStoragePool> MapStorageUuidToStoragePool = new HashMap<>();
 
-    /** iscsiadm's ISCSI_ERR_NO_OBJS_FOUND: returned by "-m session" when no session is established. */
-    private static final int ISCSI_ERR_NO_OBJS_FOUND = 21;
-
-    /** iscsiadm's ISCSI_ERR_SESS_EXISTS: returned by "--login" when the session is already logged in (e.g. Ubuntu). */
-    private static final int ISCSI_SESSION_EXISTS_CODE = 15;
-
     @Override
     public KVMStoragePool createStoragePool(String uuid, String host, int port, String path, String userInfo, StoragePoolType storagePoolType, Map<String, String> details, boolean isPrimaryStorage) {
         IscsiAdmStoragePool storagePool = new IscsiAdmStoragePool(uuid, host, port, storagePoolType, this);
@@ -96,22 +85,24 @@ public KVMPhysicalDisk createPhysicalDisk(String volumeUuid, KVMStoragePool pool
 
     @Override
     public boolean connectPhysicalDisk(String volumeUuid, KVMStoragePool pool, Map<String, String> details, boolean isVMMigrate) {
-        final String host = pool.getSourceHost();
-        final int port = pool.getSourcePort();
-        final String iqn = getIqn(volumeUuid);
-
         // ex. sudo iscsiadm -m node -T iqn.2012-03.com.test:volume1 -p 192.168.233.10:3260 -o new
         Script iScsiAdmCmd = new Script(true, "iscsiadm", 0, logger);
 
         iScsiAdmCmd.add("-m", "node");
-        iScsiAdmCmd.add("-T", iqn);
-        iScsiAdmCmd.add("-p", host + ":" + port);
+        iScsiAdmCmd.add("-T", getIqn(volumeUuid));
+        iScsiAdmCmd.add("-p", pool.getSourceHost() + ":" + pool.getSourcePort());
         iScsiAdmCmd.add("-o", "new");
 
         String result = iScsiAdmCmd.execute();
 
-        if (!handleNodeCreateResult(result, volumeUuid)) {
+        if (result != null) {
+            logger.debug("Failed to add iSCSI target " + volumeUuid);
+            System.out.println("Failed to add iSCSI target " + volumeUuid);
+
             return false;
+        } else {
+            logger.debug("Successfully added iSCSI target " + volumeUuid);
+            System.out.println("Successfully added to iSCSI target " + volumeUuid);
         }
 
         String chapInitiatorUsername = details.get(DiskTO.CHAP_INITIATOR_USERNAME);
@@ -132,10 +123,24 @@ public boolean connectPhysicalDisk(String volumeUuid, KVMStoragePool pool, Map<S
             }
         }
 
-        // Login is always attempted (idempotent). Rescan runs only if the session already existed
-        // before login (Oracle re-login exits 0; Ubuntu may return ISCSI_ERR_SESS_EXISTS).
-        if (!loginOrRescanExistingSession(iqn, host, port, volumeUuid)) {
+        // ex. sudo iscsiadm -m node -T iqn.2012-03.com.test:volume1 -p 192.168.233.10:3260 --login
+        iScsiAdmCmd = new Script(true, "iscsiadm", 0, logger);
+
+        iScsiAdmCmd.add("-m", "node");
+        iScsiAdmCmd.add("-T", getIqn(volumeUuid));
+        iScsiAdmCmd.add("-p", pool.getSourceHost() + ":" + pool.getSourcePort());
+        iScsiAdmCmd.add("--login");
+
+        result = iScsiAdmCmd.execute();
+
+        if (result != null) {
+            logger.debug("Failed to log in to iSCSI target " + volumeUuid);
+            System.out.println("Failed to log in to iSCSI target " + volumeUuid);
+
             return false;
+        } else {
+            logger.debug("Successfully logged in to iSCSI target " + volumeUuid);
+            System.out.println("Successfully logged in to iSCSI target " + volumeUuid);
         }
 
         // There appears to be a race condition where logging in to the iSCSI volume via iscsiadm
@@ -148,137 +153,24 @@ public boolean connectPhysicalDisk(String volumeUuid, KVMStoragePool pool, Map<S
         // After a certain number of tries and a certain waiting period in between tries,
         // this method could still return (it should not block indefinitely) (the race condition
         // isn't solved here, but made highly unlikely to be a problem).
-        // If the by-path is missing or is a regular file (not the iSCSI block symlink), size
-        // stays 0. Return false so connect does not succeed and a raw file is not created at
-        // that by-path in place of the real LUN device.
-        if (!waitForDiskToBecomeAvailable(volumeUuid, pool)) {
-            logger.warn("iSCSI device not ready for target {} at {}:{} after wait", volumeUuid, host, port);
-            return false;
-        }
+        waitForDiskToBecomeAvailable(volumeUuid, pool);
 
         return true;
     }
 
-    /**
-     * Checks the result of an iscsiadm node-create command.
-     * Returns true if the node was created or already exists, false on failure.
-     */
-    boolean handleNodeCreateResult(String result, String volumeUuid) {
-        if (result == null) {
-            logger.debug("Successfully added iSCSI node for target {}", volumeUuid);
-            return true;
-        }
-        String msg = result.toLowerCase();
-        if (msg.contains("already exists") || msg.contains("database exists") || msg.contains("exists")) {
-            logger.debug("iSCSI node already exists for target {}, proceeding", volumeUuid);
-            return true;
-        }
-        logger.debug("Failed to add iSCSI node for target {}: {}", volumeUuid, result);
-        return false;
-    }
-
-    /**
-     * Checks existing session state, performs login, and rescans only if the session already existed.
-     *
-     * Login is always attempted (idempotent). A pre-login session check is required on Oracle,
-     * where re-login often exits 0; Ubuntu may instead return ISCSI_ERR_SESS_EXISTS (15).
-     * Session-preexisted must be treated as success first: on Ubuntu, re-login exits 15 with a
-     * non-null error message that would otherwise be treated as failure.
-     *
-     * @return true if login succeeded (and rescan ran when needed), false on login failure
-     */
-    private boolean loginOrRescanExistingSession(String iqn, String host, int port, String volumeUuid) {
-        boolean sessionAlreadyActive = isIscsiSessionActive(iqn, host, port);
-        logger.debug("iSCSI session active check for target {} at {}:{}: {}", iqn, host, port, sessionAlreadyActive);
-
-        Script iScsiAdmCmd = new Script(true, "iscsiadm", 0, logger);
-        iScsiAdmCmd.add("-m", "node");
-        iScsiAdmCmd.add("-T", iqn);
-        iScsiAdmCmd.add("-p", host + ":" + port);
-        iScsiAdmCmd.add("--login");
-
-        String result = iScsiAdmCmd.execute();
-        boolean sessionPreExisted = (iScsiAdmCmd.getExitValue() == ISCSI_SESSION_EXISTS_CODE) || sessionAlreadyActive;
-
-        if (sessionPreExisted) {
-            logger.debug("iSCSI session for target {} at {}:{} pre-existed, performing rescan", iqn, host, port);
-            rescanIscsiSessions(iqn, host, port);
-            return true;
-        }
-        if (result == null) {
-            logger.debug("Successfully logged in to iSCSI target {}", volumeUuid);
-            return true;
-        }
-        logger.debug("Failed to log in to iSCSI target {}: {}", volumeUuid, result);
-        return false;
-    }
-
-    /**
-     * Checks whether a session to the given target and portal is already established.
-     *
-     * "iscsiadm -m session" exits with ISCSI_ERR_NO_OBJS_FOUND when no session exists, which is a
-     * normal outcome here. Any other non-zero exit is logged and treated as not confirmed active.
-     */
-    private boolean isIscsiSessionActive(String iqn, String host, int port) {
-        Script sessionCmd = new Script(true, "iscsiadm", 0, logger);
-        sessionCmd.add("-m", "session");
-
-        OutputInterpreter.AllLinesParser parser = new OutputInterpreter.AllLinesParser();
-        sessionCmd.executeIgnoreExitValue(parser, ISCSI_ERR_NO_OBJS_FOUND);
-        int exitValue = sessionCmd.getExitValue();
-        if (exitValue != 0 && exitValue != ISCSI_ERR_NO_OBJS_FOUND) {
-            logger.warn("Unable to determine iSCSI session state for target {} at {}:{}: 'iscsiadm -m session' exited with {}",
-                    iqn, host, port, exitValue);
-            return false;
-        }
-
-        String sessions = parser.getLines();
-        if (StringUtils.isBlank(sessions)) {
-            return false;
-        }
-        // AllLinesParser uses BufferedReader.readLine() (strips \n, \r\n, and \r) and then
-        // appends "\n" after each session. split("\n") depends on that separator to walk
-        // one session per line when multiple sessions are listed.
-        for (String line : sessions.split("\n")) {
-            if (line.contains(iqn) && line.contains(host)) {
-                return true;
-            }
-        }
-
-        return false;
-    }
-
-    private void rescanIscsiSessions(String iqn, String host, int port) {
-        Script rescanCmd = new Script(true, "iscsiadm", 0, logger);
-        rescanCmd.add("-m", "node");
-        rescanCmd.add("-T", iqn);
-        rescanCmd.add("-p", host + ":" + port);
-        rescanCmd.add("--rescan");
-        String rescanResult = rescanCmd.execute();
-        if (rescanResult != null) {
-            logger.warn("iSCSI session rescan returned: {}", rescanResult);
-        } else {
-            logger.debug("iSCSI session rescan completed successfully for {}@{}:{}", iqn, host, port);
-        }
-    }
-
-    private boolean waitForDiskToBecomeAvailable(String volumeUuid, KVMStoragePool pool) {
+    private void waitForDiskToBecomeAvailable(String volumeUuid, KVMStoragePool pool) {
         int numberOfTries = 10;
         int timeBetweenTries = 1000;
-        long deviceSize = 0;
 
-        while ((deviceSize = getPhysicalDisk(volumeUuid, pool).getSize()) == 0 && numberOfTries > 0) {
+        while (getPhysicalDisk(volumeUuid, pool).getSize() == 0 && numberOfTries > 0) {
             numberOfTries--;
 
             try {
                 Thread.sleep(timeBetweenTries);
-            } catch (InterruptedException ex) {
-                logger.warn("Interrupted while waiting for iSCSI device {} to become available", volumeUuid, ex);
-                return false;
+            } catch (Exception ex) {
+                // don't do anything
             }
         }
-
-        return deviceSize > 0;
     }
 
     private void waitForDiskToBecomeUnavailable(String host, int port, String iqn, String lun) {
@@ -346,25 +238,6 @@ public KVMPhysicalDisk getPhysicalDisk(String volumeUuid, KVMStoragePool pool) {
     }
 
     private long getDeviceSize(String deviceByPath) {
-        try {
-            Path devicePath = Paths.get(deviceByPath);
-            if (!Files.exists(devicePath)) {
-                logger.debug("Device by-path does not exist yet: {}", deviceByPath);
-                return 0L;
-            }
-            if (Files.isRegularFile(devicePath)) {
-                logger.warn("Found a corrupt regular file at iSCSI by-path {} (expected block device symlink); it must be removed manually", deviceByPath);
-                return 0L;
-            }
-            if (!Files.isSymbolicLink(devicePath)) {
-                logger.warn("Path {} exists but is not an iSCSI block device symlink", deviceByPath);
-                return 0L;
-            }
-        } catch (Exception ex) {
-            // If FS check fails for any reason, fall back to blockdev call
-            logger.error("Error fetching device size for {}", deviceByPath, ex);
-        }
-
         Script iScsiAdmCmd = new Script(true, "blockdev", 0, logger);
 
         iScsiAdmCmd.add("--getsize64", deviceByPath);
@@ -407,96 +280,8 @@ private String getComponent(String path, int index) {
         return tmp[index].trim();
     }
 
-    /**
-     * Check if there are other LUNs on the same iSCSI target (IQN) that are still
-     * visible as block devices. This is needed because ONTAP uses a single IQN per
-     * SVM — logging out of the target would kill ALL LUNs, not just the one being
-     * disconnected.
-     *
-     * Checks /dev/disk/by-path/ for symlinks matching the same host:port + IQN but
-     * with a different LUN number.
-     */
-    private boolean hasOtherActiveLuns(String host, int port, String iqn, String lun) {
-        String prefix = "ip-" + host + ":" + port + "-iscsi-" + iqn + "-lun-";
-        File byPathDir = new File("/dev/disk/by-path");
-        if (!byPathDir.exists() || !byPathDir.isDirectory()) {
-            return false;
-        }
-        File[] entries = byPathDir.listFiles();
-        if (entries == null) {
-            return false;
-        }
-        for (File entry : entries) {
-            String name = entry.getName();
-            // Skip partition entries (e.g. lun-0-part1, lun-0-part2) — these are not
-            // independent LUNs, they are partition symlinks for the same LUN disk.
-            // Only count actual LUN entries (no "-part" suffix after the lun number).
-            if (name.startsWith(prefix) && !name.equals(prefix + lun) && !name.contains("-part")) {
-                logger.debug("Found other active LUN on same target: " + name);
-                return true;
-            }
-        }
-        return false;
-    }
-
-    /**
-     * Removes a single stale SCSI device from the kernel using the sysfs interface.
-     *
-     * When ONTAP unmaps a LUN from the host's igroup, the by-path symlink and the
-     * underlying SCSI device (/dev/sdX) remain present in the kernel until explicitly
-     * removed — the kernel does not auto-remove devices from live iSCSI sessions.
-     *
-     * This method resolves the by-path symlink to the real block device name (e.g. sdd),
-     * then writes "1" to /sys/block/<dev>/device/delete — the standard Linux kernel SCSI
-     * API for removing a single device without tearing down the entire iSCSI session.
-     * Once the kernel processes the delete, it also removes the by-path symlink.
-     *
-     * This is used instead of iscsiadm --logout when other LUNs on the same IQN are still
-     * active (ONTAP single-IQN-per-SVM model), since logout would tear down ALL LUNs.
-     */
-    private void removeStaleScsiDevice(String host, int port, String iqn, String lun) {
-        String byPath = getByPath(host, port, "/" + iqn + "/" + lun);
-        Path byPathLink = Paths.get(byPath);
-        if (!Files.exists(byPathLink)) {
-            logger.debug("by-path entry for LUN " + lun + " already gone, nothing to remove");
-            return;
-        }
-        try {
-            Path realDevice = byPathLink.toRealPath();
-            String devName = realDevice.getFileName().toString();
-            File deleteFile = new File("/sys/block/" + devName + "/device/delete");
-            if (!deleteFile.exists()) {
-                logger.warn("sysfs delete entry not found for device " + devName + " — cannot remove stale SCSI device");
-                return;
-            }
-            try (FileWriter fw = new FileWriter(deleteFile)) {
-                fw.write("1");
-            }
-            logger.info("Removed stale SCSI device " + devName + " for LUN /" + iqn + "/" + lun + " via sysfs");
-        } catch (Exception e) {
-            logger.warn("Failed to remove stale SCSI device for LUN /" + iqn + "/" + lun + ": " + e.getMessage());
-        }
-    }
-
     private boolean disconnectPhysicalDisk(String host, int port, String iqn, String lun) {
-        // Check if other LUNs on the same IQN target are still in use.
-        // ONTAP (and similar) uses a single IQN per SVM with multiple LUNs.
-        // Doing iscsiadm --logout tears down the ENTIRE target session,
-        // which would destroy access to ALL LUNs — not just the one being disconnected.
-        if (hasOtherActiveLuns(host, port, iqn, lun)) {
-            logger.info("Skipping iSCSI logout for /" + iqn + "/" + lun +
-                    " — other LUNs on the same target are still active. Removing stale SCSI device for this LUN only.");
-            removeStaleScsiDevice(host, port, iqn, lun);
-            // After removing this LUN's device, re-check: if no other LUNs remain active,
-            // If it is the last one then must logout to clean up the iSCSI session entirely.
-            if (hasOtherActiveLuns(host, port, iqn, lun)) {
-                logger.info("Other LUNs still active after removing /" + iqn + "/" + lun + " — session kept alive.");
-                return true;
-            }
-            logger.info("No more active LUNs on target after removing /" + iqn + "/" + lun + " — proceeding with iSCSI logout.");
-        }
-
-        // No other LUNs active on this target — safe to logout and delete the node record.
+        // use iscsiadm to log out of the iSCSI target and un-discover it
 
         // ex. sudo iscsiadm -m node -T iqn.2012-03.com.test:volume1 -p 192.168.233.10:3260 --logout
         Script iScsiAdmCmd = new Script(true, "iscsiadm", 0, logger);
@@ -602,8 +387,8 @@ public List<KVMPhysicalDisk> listPhysicalDisks(String storagePoolUuid, KVMStorag
 
     @Override
     public KVMPhysicalDisk createDiskFromTemplate(KVMPhysicalDisk template, String name, PhysicalDiskFormat format,
-            ProvisioningType provisioningType, long size,
-            KVMStoragePool destPool, int timeout, byte[] passphrase) {
+                                                  ProvisioningType provisioningType, long size,
+                                                  KVMStoragePool destPool, int timeout, byte[] passphrase) {
         throw new UnsupportedOperationException("Creating a disk from a template is not yet supported for this configuration.");
     }
 
@@ -637,19 +422,6 @@ public KVMPhysicalDisk copyPhysicalDisk(KVMPhysicalDisk srcDisk, String destVolu
         try {
             QemuImg q = new QemuImg(timeout);
             q.convert(srcFile, destFile);
-            // Below fix is required when vendor depends on host based copy rather than storage CAN_CREATE_VOLUME_FROM_VOLUME capability
-            // When host based template copy is triggered , small size template sits in RAM(depending on host memory and RAM) and copy is marked successful and by the time flush to storage is triggered
-            // disconnectPhysicalDisk would disconnect the lun , hence template staying in RAM is not copied to storage lun. Below does flushing of data to storage and marking
-            // copy as successful once flush is complete.
-            Script flushCmd = new Script(true, "blockdev", 0, logger);
-            flushCmd.add("--flushbufs", destDisk.getPath());
-            String flushResult = flushCmd.execute();
-            if (flushResult != null) {
-                logger.warn("iSCSI copyPhysicalDisk: blockdev --flushbufs returned: {}", flushResult);
-            }
-            Script syncCmd = new Script(true, "sync", 0, logger);
-            syncCmd.execute();
-            logger.info("iSCSI copyPhysicalDisk: flush/sync completed ");
         } catch (QemuImgException | LibvirtException ex) {
             String msg = "Failed to copy data from " + srcDisk.getPath() + " to " +
                     destDisk.getPath() + ". The error was the following: " + ex.getMessage();